The Training Support Column MkII

[Xiva]

And is way better for your shoulder health.

Agree.

Infront is alot better for your rotator manchett

 

[tim290280]

For all you leg press junkies, you aren't lifting anywhere near as much as you think you are.

Relationship Between Plate Mass and Actual Leg Press Loads.

Abstract
Journal of Strength & Conditioning Research. 24 Supplement 1:1, January 2010.
Clemons, Jim

Abstract:
When using a typical leg press machine there is no way of knowing the actual weight that is lifted. The only information available to the lifter is the added plate mass and perhaps sled weight if the manufacturer's specifications are available. Unfortunately, knowledge of sled weight is not very helpful because a portion of that weight is supported by the frame. The purpose of this study is to determine accurate resistance loads beginning first with only the sled and then progressively adding 4.54 kg up to a maximum load of 454.55 kg. A load cell was attached to the frame of an LE408 BM Leg Press Machine and oriented so that it was in the same slide plane as the sled. It was calibrated by the manufacturer to the control unit that accompanied it and, according to specifications, is accurate to +/- 0.2 kg and has a maximum capacity of 453.5 kg. The sled was pushed from its supports and hooked to the lower portion of a chain serially attached to the load cell and upper frame. The data acquisition system was zeroed out to eliminate the weight of the load cell and the lower chain. The sled was slowly lowered until the weight of the sled and any added weight was fully supported by the load cell. Once motionless, the measurement system was subsequently activated at a sampling rate of 40 measurements [middle dot] sec-1. Peak measurements were captured by the control unit. Pearson Product Moment correlation was used to determine the relationship between plate mass and the associated peak force measures captured from the system beginning with 4.54 kg up to 454.55 kg: (r = 1), p = 0.000. Results indicated that when 0 plates were on the machine, the lifter must overcome 49.6 kg of resistance to move the sled. As plate mass increased, resistance also increased. The ratio of plate mass to load lifted began at 0.086 with two 2.27 kg plates on the apparatus and gradually increased to 1.00 with 140.9 kg of plate mass and a measured resistance of 140.7 kg. Up to this point, the measured resistance exceeded total plate mass due to the additive sled component; however, beyond 140.9 kg of plate mass ratios began to exceed 1 presumably due to progressively more weight being transferred to the frame. At 454.55 kg (1000 lbs) on the machine, the actual resistance that would be overcome by a lifter would be 342.1 kg (752.6 lbs) at a ratio of 1.329. The linear regression formula generated was: Mass lifted = (0.64 [middle dot] total plate mass in kg) + 50.26 kg. Obtaining accurate knowledge of lifting loads will have testing benefits and will likely produce better estimates of free weight squatting ability.

Keep your compression garments on after training, it helps you recover.

Effects Of A Whole Body Compression Garment On Markers Of Recovery After An Intense Whole Body Resistance Training Workout In Men.

Abstract
Journal of Strength & Conditioning Research. 24 Supplement 1:1, January 2010.
Flanagan, Shawn

Abstract:
The primary purpose of this investigation was to evaluate the influence of a whole body compression garment on recovery from a typical heavy resistance training workout in resistance trained men. Eleven resistance trained men [mean +/- SD, age (yr) 23.0 +/- 2.9, height (cm) 178.5 +/- 9.9, body mass (kg) 86.1 +/- 9.7] gave informed consent to participate in the study. A within-group [each subject acted as their own control], balanced and randomized treatment design was used. A whole body heavy resistance exercise protocol using barbells [3sets 8-10 RM, 2.0-2.5 min rest] consisting of a back squat, bench press, stationary lunge, bent over row, Romanian dead lift, biceps curl, sit-ups and high pull from a hang was performed after which the subject showered and put on a whole body compression garment (CG) (75% Nylon and 25% Spandex,) or just wore his normal non-compression clothing (CON). Subjects were then tested 24 hr later in the laboratory immediately after they removed the compression garment and put on their workout attire in order to determine recovery differences between conditions. Nutritional intakes, activity, and behavioral patterns (e.g., no pain medications, ice or long showers over the 24 hr) were replicated with test protocol sequences separated by 72 hours. Dependent measures included, sleep quality, vitality rating, resting fatigue rating, muscle soreness, muscle swelling via ultrasound, reaction movement times, bench throw power, countermovement vertical jump power (CMVJ), and serum concentrations of creatine kinase (CK) measured from a blood sample obtained via venipuncture of an arm vein. An analysis of variance was used to determine differences between treatments and p <=0.05 was defined as significance in this study. There was no significant difference in sleep quality between conditions; vitality rating, with 7 the highest quality rating, the CG [6.0 + 0.5] was significantly higher than CON [2.9 + 1.1], resting fatigue was significantly lower in CG [1.75 + 0.84] vs CON [3.77 + 1.25], muscle soreness was significantly lower in CG [1.33 + 0.65] vs CON [3.06 + 2.1], muscle swelling was significantly lower in CG [18.8 + 4.0 cm] vs CON [23.7 + 2.6 cm], no differences were observed in reaction/movement time, bench press throw power was significantly higher in CG [950.3 + 193.3 W] vs CON [705.4 + 292.9 W], no differences for CMVJ, and resting CK was significantly lower in CG [318 + 188 IU/L] vs CON [597 + 330 IU/L]. A whole body compression garment worn during the 24 hr recovery period after an intense heavy resistance training workout enhances various psychological, physiological and performance markers of recovery compared to control garment conditions. The use of compression has been previously shown to help athletic performance, reduce damage from soft tissue injury and now it appears that compression can help in the recovery process from an intense resistance training workout in men.

 

[tim290280]

Another nail in the HIT coffin; shit for strength, shit for hypertrophy:

Journal of Strength and Conditioning Research:
April 2010 - Volume 24 - Issue 4 - pp 1150-1159

Single vs. Multiple Sets of Resistance Exercise for Muscle Hypertrophy: A Meta-AnalysisKrieger, James W
Abstract
Previous meta-analyses have compared the effects of single to multiple sets on strength, but analyses on muscle hypertrophy are lacking. The purpose of this study was to use multilevel meta-regression to compare the effects of single and multiple sets per exercise on muscle hypertrophy. The analysis comprised 55 effect sizes (ESs), nested within 19 treatment groups and 8 studies. Multiple sets were associated with a larger ES than a single set (difference = 0.10 ± 0.04; confidence interval [CI]: 0.02, 0.19; p = 0.016). In a dose-response model, there was a trend for 2-3 sets per exercise to be associated with a greater ES than 1 set (difference = 0.09 ± 0.05; CI: −0.02, 0.20; p = 0.09), and a trend for 4-6 sets per exercise to be associated with a greater ES than 1 set (difference = 0.20 ± 0.11; CI: −0.04, 0.43; p = 0.096). Both of these trends were significant when considering permutation test p values (p < 0.01). There was no significant difference between 2-3 sets per exercise and 4-6 sets per exercise (difference = 0.10 ± 0.10; CI: −0.09, 0.30; p = 0.29). There was a tendency for increasing ESs for an increasing number of sets (0.24 for 1 set, 0.34 for 2-3 sets, and 0.44 for 4-6 sets). Sensitivity analysis revealed no highly influential studies that affected the magnitude of the observed differences, but one study did slightly influence the level of significance and CI width. No evidence of publication bias was observed. In conclusion, multiple sets are associated with 40% greater hypertrophy-related ESs than 1 set, in both trained and untrained subjects.

Journal of Strength and Conditioning Research:
April 2010 - Volume 24 - Issue 4 - pp 1074-1081

Anabolic and Catabolic Hormones and Energy Balance of the Male Bodybuilders During the Preparation for the CompetitionMäestu, Jarek; Eliakim, Alon; Jürimäe, Jaak; Valter, Ivo; Jürimäe, Toivo

Abstract
The purpose of the study was to investigate simultaneous effects of energy balance, caloric intake, and the hormonal anabolic-catabolic balance in bodybuilders prior to competition. Fourteen male bodybuilders took part in an 11-week energy-restricted period to reduce body fat. The subjects were divided into the energy-restricted group (ERG) (n = 7), who were preparing for the competition, or the control group (CG) (n = 7) who continued to train regularly and did not change their dietary or training pattern. Participants were tested at 11 weeks (T1), 5 weeks (T2), and 3 days (T3) before competition for diet, body composition, and fasting hormonal assessment. Body mass and body fat percentage of ERG were significantly (p < 0.05) decreased during the study period. In ERG, insulinlike growth factor-1 (IGF-1) and insulin decreased significantly during the 11-week weight-reduction period (p < 0.05). Testosterone was decreased only from week 11 to week 5 (from 20.3 ± 6.0 to 18.0 ± 6.8 nmol/L). Changes in IGF-I concentration were significantly related to changes in insulin (r = 0.741), fat mass (r = 0.705), lean body mass (r = 0.696), and body mass (r = 0.652). Changes in insulin concentrations were significantly related to changes in fat mass (r = 0.630) and lean body mass (r = 0.725). These data indicate that severe energy restriction to extremely low body energy reserves decreases significantly the concentrations of 3 anabolic pathways despite high protein intake. Monitoring of insulin and IGF-1 concentration is suggested to prevent losses in muscle mass in energy-restricted conditions. Other nutritional strategies might be needed to prevent possible catabolic effect during preparation of bodybuilders to competition.

 

[tim290280]

Arginine may actually have some value after-all:

Journal of Strength and Conditioning Research:
May 2010 - Volume 24 - Issue 5 - pp 1306-1312

Effects of Arginine-Based Supplements on the Physical Working Capacity at the Fatigue Threshold

Camic, Clayton L; Housh, Terry J; Zuniga, Jorge M; Hendrix, Russell C; Mielke, Michelle; Johnson, Glen O; Schmidt, Richard J

Abstract
The purpose of the present study was to examine the effects of daily oral administration of arginine-based supplements for 4 weeks on the physical working capacity at the fatigue threshold (PWCFT). The PWCFT test is an electromyographic (EMG) procedure for estimating the highest power output that can be maintained without neuromuscular evidence of fatigue. The study used a double-blind, placebo-controlled design. Fifty college-aged men (mean age ± SD = 23.9 ± 3.0) were randomized into 1 of 3 groups: (a) placebo (n = 19); (b) 1.5 g arginine (n = 14); or (c) 3.0 g arginine (n = 17). The placebo was microcrystalline cellulose. The 1.5-g arginine group ingested 1.5 g of arginine and 300 mg of grape seed extract, whereas the 3.0 g arginine group ingested 3.0 g of arginine and 300 mg of grape seed extract. All subjects performed an incremental test to exhaustion on a cycle ergometer to determine their PWCFT before supplementation (PRE) and after 4 weeks of supplementation (POST). Surface EMG signals were recorded from the vastus lateralis using a bipolar electrode arrangement during the incremental tests for the determination of the PRE and POST supplementation PWCFT values. There were significant mean increases (PRE to POST) in PWCFT for the 1.5 g (22.4%) and 3.0 g (18.8%) supplement groups, but no change for the placebo group (−1.6%). These findings supported the use of arginine-based supplements, at the dosages examined in the present investigation, as an ergogenic aid for untrained individuals.

Don't stretch too much between sets:

Journal of Strength and Conditioning Research:
May 2010 - Volume 24 - Issue 5 - pp 1361-1368

Interset Stretching Does Not Influence the Kinematic Profile of Consecutive Bench-Press Sets
García-López, David; Izquierdo, Mikel; Rodríguez, Sergio; González-Calvo, Gustavo; Sainz, Nuria; Abadía, Olaia; Herrero, Azael J

Abstract
This study was undertaken to examine the role of interset stretching on the time course of acceleration portion AP and mean velocity profile during the concentric phase of 2 bench-press sets with a submaximal load (60% of the 1 repetition maximum). Twenty-five college students carried out, in 3 different days, 2 consecutive bench-press sets leading to failure, performing between sets static stretching, ballistic stretching, or no stretching. Acceleration portion and lifting velocity patterns of the concentric phase were not altered during the second set, regardless of the stretching treatment performed. However, when velocity was expressed in absolute terms, static stretching reduced significantly (p <0.05) the average lifting velocity during the second set compared to the first one. Therefore, if maintenance of a high absolute velocity over consecutive sets is important for training-related adaptations, static stretching should be avoided or replaced by ballistic stretching.

 

[Big_Guns_Lance]

Journal of Strength and Conditioning Research:
April 2010 - Volume 24 - Issue 4 - pp 1150-1159

Single vs. Multiple Sets of Resistance Exercise for Muscle Hypertrophy: A Meta-AnalysisKrieger, James W
Abstract
Previous meta-analyses have compared the effects of single to multiple sets on strength, but analyses on muscle hypertrophy are lacking. The purpose of this study was to use multilevel meta-regression to compare the effects of single and multiple sets per exercise on muscle hypertrophy. The analysis comprised 55 effect sizes (ESs), nested within 19 treatment groups and 8 studies. Multiple sets were associated with a larger ES than a single set (difference = 0.10 ± 0.04; confidence interval [CI]: 0.02, 0.19; p = 0.016). In a dose-response model, there was a trend for 2-3 sets per exercise to be associated with a greater ES than 1 set (difference = 0.09 ± 0.05; CI: −0.02, 0.20; p = 0.09), and a trend for 4-6 sets per exercise to be associated with a greater ES than 1 set (difference = 0.20 ± 0.11; CI: −0.04, 0.43; p = 0.096). Both of these trends were significant when considering permutation test p values (p < 0.01). There was no significant difference between 2-3 sets per exercise and 4-6 sets per exercise (difference = 0.10 ± 0.10; CI: −0.09, 0.30; p = 0.29). There was a tendency for increasing ESs for an increasing number of sets (0.24 for 1 set, 0.34 for 2-3 sets, and 0.44 for 4-6 sets). Sensitivity analysis revealed no highly influential studies that affected the magnitude of the observed differences, but one study did slightly influence the level of significance and CI width. No evidence of publication bias was observed. In conclusion, multiple sets are associated with 40% greater hypertrophy-related ESs than 1 set, in both trained and untrained subjects.

I am glad I closed the door on HIT myself. I made some progress when I began (due to the increased intensity from what I had previously been used to doing) but i soon started to stagnate. Never will i go back to HIT and I wouldn't advise anyone to even think of it. There are productive routines out there.

I have the full PDF of the review if anyone is interested.

 

[tim290280]

^^ Post or mention the pdf in the thread I started (and just bumped) in the articles section. I didn't bother downloading the pdf, so I wouldn't mind it myself.

 

[El Freako]

I'll have the PDF thanks Lance.

PMing you the addy.

 

[Big_Guns_Lance]

^^ Post or mention the pdf in the thread I started (and just bumped) in the articles section. I didn't bother downloading the pdf, so I wouldn't mind it myself.

I copied and pasted it in articles section and then previewed it and it messed up the layout. Either PM me your email or freako can send it you.

 

[tim290280]

Freako knows my addy. Ben, if you would please.

 

[Cork]

I love updates to this thread, even if it only reinforces posts that were made previously.

Tim, I'm curious about the article on anabolic and catabolic hormones during contest prep. The end of the abstract suggests different dietary needs. Does the article itself offer up any options or is the point to only quantify the change during the 12 week period? Who couldn't assume that anabolic hormone activity is decreased?

 

[tim290280]

^^ I've been trying to log onto the journals to post the entire thing and I can't seem to. I'll try again later.

 

[tim290280]

A Comparison of Free Weight Squat to Smith Machine Squat Using Electromyography

Schwanbeck, Shane; Chilibeck, Philip D; Binsted, Gordon

Abstract
The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured. Electromyographic activity was significantly higher by 34, 26, and 49 in the gastrocnemius, biceps femoris, and vastus medialis, respectively, during the free weight squat compared to the Smith machine squat (p < 0.05). There were no significant differences between free weight and Smith machine squat for any of the other muscles; however, the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p < 0.05). The free weight squat may be more beneficial than the Smith machine squat for individuals who are looking to strengthen plantar flexors, knee flexors, and knee extensors.

Introduction

Free weights are generally preferred over machines by body builders and strength-trained athletes because they are thought to provide a more unstable exercise, requiring a greater recruitment of trunk musculature (5). Machines, however, are easier to use by beginners and require spotters less often than free weight exercise (5). Few studies have compared free weight and machine exercises of similar movement pattern to determine which is optimal for muscle activation.


Free weight squat is one of the most popular exercises used by strength-trained athletes for training leg musculature. The Smith machine allows one to perform a similar type of movement, where the barbell is stabilized in 2 parallel tracks, allowing a more stable exercise. Anderson and Behm (1) compared electromyographic (EMG) activity during squat exercises using free weights and the Smith machine. They found that there was a trend for EMG activity of the trunk musculature to be greater during the free weight squat; however, EMG activity of the quadriceps (i.e., vastus lateralis) was highest during the Smith machine squats. One limitation of this study was that the same absolute weight was used for both exercises. The relative intensity during the most stable condition (i.e., Smith machine squats) would have been low because muscle force production during this movement is superior to the more unstable free weight squat (3). The purpose of the current study was to reassess EMG activity of prime movers and stabilizers during the squat exercise using free weights and the Smith machine where the load lifted was the maximal one could lift over 8 repetitions on each exercise (i.e., loads were set relative to each exercise; therefore, different absolute loads were used). We believe this has greater applicability to actual resistance-training situations when one is selecting training loads to achieve a desired number of repetitions. It was hypothesized that (a) in a stable environment (Smith machine) prime movers (i.e., muscles of the upper leg) activity would be higher and (b) in an unstable environment (free weight) stabilizer (i.e., muscles of the trunk and lower leg) activity would be higher.

Methods

Experimental Approach to the Problem

This study was designed to compare electromyographic activity of the legs (i.e., tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris) and trunk stabilizers (i.e., lumbar erector spinae and rectus abdominus) during free weight and Smith machine squat exercises to determine which exercise was optimal for activating musculature. Resistance was selected for each exercise to achieve 8 maximal repetitions (8RM) to match what a typical strength-trained athlete would select during a training set.

Subjects

Six healthy participants (3 males and 3 females, 22 ± 1.2 years, 171 ± 12 cm, 71.5 ± 12.7 kg), all with previous strength training experience (2-5 years), were involved in this study. All participants were active in sports (i.e., basketball, track, or squash) and had trained on both free weights and machines. All participants were currently involved in resistance training at least 3 days per week. The study took place from January to March. Subjects were informed of the experimental risks and signed an informed consent document prior to the investigation. The investigation was approved by an Institutional Review Board for use of human subjects.

Procedures

Each participant performed 8RM of Smith machine squat and free weight squat with the order randomized while EMG activity of 7 muscles was assessed. Testing sessions were at least 3 days apart.


Recording sites for EMG were prepared by shaving the area and wiping with alcohol pads to decrease electrical impedance. Electrodes were placed on the dominant side of the participant's body; this was the right side for all 6 participants. Electrodes were placed two thirds distally between the greater trochanter and the lateral condyle on the vastus medialis and vastus lateralis, mid-belly of the biceps femoris parallel to the quadriceps landmark, distal part of the lateral head of the gastrocnemius, mid-belly of the tibialis anterior, medial rectus abdominus (approximately 6 cm superior and 4 cm lateral of the umbilicus), and lumbar erector spinae (approximately 6 cm lateral to the L1-L2 spinous processes). For the purpose of this study the prime movers were considered the vastus medialis, vastus lateralis, and biceps femoris. The lower-limb stabilizers included the tibialis anterior and lateral gastrocnemius. The trunk stabilizers included the rectus abdominus and the lumbar erector spinae. Ground sites included the tibial tuberosity, iliac crest, and lateral malleolus of the fibula.


The EMG main amplifier unit included single differential electrodes with a bandwidth of 10 Hz to 1,000 Hz. The overall amplification or gain per channel was between 5,000 and 10,000 dB and was set according to individual subjects to maximize the digital range without saturating the signal. The electrodes were Ag/AgCl surface electrodes (2.4 cm × 2.4 cm) spaced 2 cm apart and aligned parallel to muscle fiber orientation. The EMG was recorded as raw EMG (V) and stored in the computer for analysis. The sampling rate was set at 500 Hz for 60 seconds. After data collection, the raw EMG data were used to calculate a mean absolute value (MAV) for each repetition in the 8RM. The EMG signal was not normalized because the experiment was a repeated-measures design comparing within individuals. Testing sessions were at least 3 days apart for the 2 conditions. A permanent marker was used to identify electrode placement on the first testing session so that identical electrode placement could be used during the second testing session. Identical amplification was used for each collection period within individual subjects. Intraclass correlation coefficients for EMG MAV for test-retest reliability (i.e., at least 3 days apart for the 6 individuals) were 0.93 for tibialis anterior, 0.95 for gastrocnemius, 0.80 for vastus lateralis, 0.84 for vastus medialis, 0.82 for biceps femoris, 0.90 for medial rectus abdominus, and 0.67 for erector spinae.


Participants were required to attend 2 pre-experimental exercise testing sessions during which a weight that could be lifted for 8 repetitions during a squat exercise using free weights (i.e., a barbell and weights) and the Smith machine were determined. This process consisted of performing 2 to 3 warm-up sets and then 2 to 3 working sets. The working sets consisted of choosing a weight that the participants thought they could do for 8 repetitions and was adjusted throughout these sets to meet the desired repetitions. Rest intervals were 4 to 5 minutes between sets. The Smith machine was composed of a rack that fully supports a regular Olympic barbell, therefore completely stabilizing the barbell. The barbell can be moved up and down the rack so that the user can perform a variety of exercises including squats. Approximately 1 week later participants were randomly assigned to perform 8 repetitions of squat exercise with free weights or the Smith machine while their EMG activity was recorded. Participants returned within a minimum of 3 days to have their muscle activity measured while performing 8 repetitions on the opposite exercise. We chose to make comparisons between the 2 training modes with the same relative load (i.e., 8RM) rather than the same absolute load because this provides a greater simulation of real-life training practices (i.e., one usually aims for a given number of repetitions, rather than selecting the same absolute load, when training for 2 different exercises). This resulted in a heavier weight used (by 14-23 kg) by each individual on the Smith machine compared to the free weight squat. Each testing session consisted of 2 to 3 warm-up sets with light weight and 1 working set. One repetition was performed prior to the working set with the appropriate weight for 8 repetitions. This allowed the amplification of the EMG to be adjusted to prevent saturated signals. Participants were reminded of the basic squatting technique but were encouraged to use their natural technique they were accustomed to from their previous experiences. Participants were instructed to go to approximately 90 degrees of knee flexion and were given feedback when this was achieved.

Statistical Analyses

A repeated measures analysis of variance (with mode of testing: free weights vs. Smith machine as the factor) for each of the 7 muscle groups was used (Statistica Version 6.0 Chicago, Illinois, USA). Statistical significance for all analyses was set at p <= 0.05. Data are reported as means ± standard deviation.

Results

The free weight squat elicited a 34% higher EMG MAV from the gastrocnemius, a 26% higher EMG MAV from the biceps femoris, and a 49% higher EMG MAV from the vastus medialis compared to the Smith machine squat (p < 0.05; Figure 1). The free weight squat also elicited a 25% higher EMG MAV from the vastus lateralis, with each subject having a higher EMG MAV during the free weight squat compared to the Smith machine squat; however, the differences between exercises did not reach a level of statistical significance (p = 0.057). Averaged over all muscle groups, the free weight squat elicited a 43% higher EMG MAV compared to the Smith machine squat (p < 0.05).

Discussion

This study was designed to have applicability to typical training sessions, where participants did free weight and Smith machine squats with heavy weights for a desired number of repetitions (i.e., 8RM). Contrary to our hypotheses, muscles of the legs (specifically the vastus medialis and biceps femoris) displayed greater EMG activity during the free weight squat compared to the Smith machine squat, whereas there were no differences between exercises for EMG activity of trunk stabilizers. In support of our hypothesis, 1 of the stabilizing muscles of the lower leg (i.e., gastrocnemius) displayed greater EMG activity during the free weight squat.


The pattern of muscle activation during our free weight squat and Smith machine squat was similar to Anderson and Behm (1), who evaluated the same exercises. The knee extensors (i.e., vastus lateralis) and erector spinae displayed a large amount of EMG activity, whereas the abdominal stabilizers, biceps femoris, and plantar flexors displayed relatively less EMG activity. Several important differences were seen between studies regarding activation of specific muscle groups across the 2 different exercises; these differences are most likely a result of the different type of loading used across the 2 studies. These differences are outlined in detail later.


Our finding of a higher biceps femoris and gastrocnemius activity during the free weight squat may be attributed to the increased role that the knee flexors play in stabilizing and supporting the ankle, knee, and hip joints in a more unstable environment. Behm et al. (2) found significantly higher EMG activity of the biceps femoris during an unstable leg extension on a Swiss ball. This may be attributed to the antagonistic role that the biceps femoris plays in relation to the vastus medialis and vastus lateralis. As a result of a muscle contraction, the antagonist may be trying to control the placement of the limb (4). To increase joint stability and stiffness, the antagonist muscle activity increases (6). Behm et al. (2) also suggest that improved balance and motor control may be attributed to increased antagonist activity. In contrast to our results, Anderson and Behm (1) found no significant difference in muscle activity of the biceps femoris between a free weight squat and Smith machine squat. These results are likely a result of differences in design compared to the current study. Most notably, they had participants perform squats with standardized submaximal loads, whereas the current study used a load specific for each exercise for which participants could complete 8RM. We feel this is more applicable to an actual training situation, where one usually selects loads based on a target number of repetitions.


Our finding of a higher gastrocnemius EMG during the free weight squat compared to the Smith machine squat is again different from the results of Anderson and Behm (1), who found similar EMG activity of the plantar flexors (i.e., soleus) across the 2 exercises. Their data, however, showed a trend for EMG activity during free weight squat to be higher. Because the distal attachment of the gastrocnemius crosses the ankle joint and the proximal attachment crosses the knee joint, this muscle probably plays an important stabilizing role during movements such as the squat, which involve both of these joints and would be activated to a greater extent during a more unstable movement (7).


In contrast to Anderson and Behm (1), we did not find the Smith machine squat to be superior for activation of the knee extensors (i.e., vastus lateralis). Our free weight squat elicited higher activity of the vastus medialis and a trend for higher activity of the vastus lateralis (p = 0.057) compared to the Smith machine squat. This result was contrary to our hypothesis, which was based on the fact that one can lift heavier loads during the Smith machine exercise because of the greater stability (3). The higher vastus medialis and vastus lateralis recruitment during the free weight squat may be attributed to the potential increase in the stabilization roles these muscles play during this exercise.


One might postulate that there would be higher activation of trunk musculature during the more unstable free weight exercise compared with the more stable Smith machine exercise (1,5); however, our findings indicate the differences only existed in activation of leg musculature. There were trends for trunk musculature to have higher activation during the free weight squat; however, the differences when compared to Smith machine squat were not significant (Figure 1). Our study is limited by a lack of power because we only had 6 subjects participate in the study. After the study we determined the number of individuals required to reach statistical significance at alpha of 0.05 and power of 80%. For our nonsignificant results, this ranged from 8 required subjects for the vastus lateralis measurement to 29 subjects for the rectus abdominus measurement. Power for comparisons of muscle groups between the 2 exercises was 48% for tibialis anterior, 59% for gastrocnemius, 51% for vastus lateralis, 84% for vastus medialis, 83% for biceps femoris, 50% for rectus abdominus, and 25% for erector spinae. Another limitation of the study is the use of both genders. The small number of subjects did not permit a statistical comparison for differences across genders; however, the differences for activation between the free weight squat and the Smith machine squat were similar between the genders (i.e., an average difference in activation of 47% for males and 37% for females).

Practical Applications

We found a 43% higher muscle activation during the free weight squat compared to the Smith machine squat. Activation of the knee extensors and flexors and ankle plantar flexors were higher during free weight squat, whereas activation of the trunk stabilizers was similar across the 2 exercises. This indicates that the free weight squat may be superior to the Smith machine squat for training the major muscle groups of the legs and possibly would result in greater strength development and hypertrophy of these muscle groups with long-term training.

Acknowledgments

We would like to acknowledge Doug Jacobson and Heather Whelan for their technical help and the participants who volunteered their time for this study.

References


1. Anderson, K and Behm, DG. Trunk muscle activity increases with unstable squat movements. Can J Appl Physiol 30: 33-45, 2005. [Context Link]


2. Behm, DG, Anderson, K, and Curnew, RS. Muscle force and activation under stable and unstable conditions. J Strength Cond Res 16: 416-422, 2002. Request Permissions [Context Link]


3. Cotterman, ML, Darby, LA, and Skelly, WA. Comparison of muscle force production using the Smith machine and free weights for bench press and squat exercises. J Strength Cond Res 19:169-176, 2005. Ovid Full Text Request Permissions [Context Link]


4. De Luca, CJ and Mambrito, B. Voluntary control of motor units in human antagonist muscles: Coactivation and reciprocal activation. J Neurophysiol 58: 525-542, 1987. [Context Link]


5. Haff, G. Roundtable discussion: Machines versus free weights. Strength Cond J 22: 18-30, 2000. Ovid Full Text Request Permissions [Context Link]


6. Hogan, N. Adaptive control of mechanical impedance by coactivation of antagonist muscles. IEEE Trans Automat Contr AC29: 681-690, 1984. [Context Link]


7. Sherbondy, PS, Queale, WS, McFarland, EG, Mizuno, Y, and Cosgarea, AJ. Soleus and gastrocnemius muscle loading decreases anterior tibial translation in anterior cruciate ligament intact and deficient knees. J Knee Surg 16: 152-58, 2003. [Context Link]


Key Words: vastus medialis; vastus lateralis; biceps femoris; tibialis anterior; gastrocnemius

 

[tim290280]

Anabolic and Catabolic Hormones and Energy Balance of the Male Bodybuilders During the Preparation for the Competition

Mäestu, Jarek1; Eliakim, Alon2; Jürimäe, Jaak1; Valter, Ivo3; Jürimäe, Toivo1

Abstract

The purpose of the study was to investigate simultaneous effects of energy balance, caloric intake, and the hormonal anabolic-catabolic balance in bodybuilders prior to competition. Fourteen male bodybuilders took part in an 11-week energy-restricted period to reduce body fat. The subjects were divided into the energy-restricted group (ERG) (n = 7), who were preparing for the competition, or the control group (CG) (n = 7) who continued to train regularly and did not change their dietary or training pattern. Participants were tested at 11 weeks (T1), 5 weeks (T2), and 3 days (T3) before competition for diet, body composition, and fasting hormonal assessment. Body mass and body fat percentage of ERG were significantly (p < 0.05) decreased during the study period. In ERG, insulinlike growth factor-1 (IGF-1) and insulin decreased significantly during the 11-week weight-reduction period (p < 0.05). Testosterone was decreased only from week 11 to week 5 (from 20.3 ± 6.0 to 18.0 ± 6.8 nmol/L). Changes in IGF-I concentration were significantly related to changes in insulin (r = 0.741), fat mass (r = 0.705), lean body mass (r = 0.696), and body mass (r = 0.652). Changes in insulin concentrations were significantly related to changes in fat mass (r = 0.630) and lean body mass (r = 0.725). These data indicate that severe energy restriction to extremely low body energy reserves decreases significantly the concentrations of 3 anabolic pathways despite high protein intake. Monitoring of insulin and IGF-1 concentration is suggested to prevent losses in muscle mass in energy-restricted conditions. Other nutritional strategies might be needed to prevent possible catabolic effect during preparation of bodybuilders to competition.

Introduction

Competitive bodybuilding is a sport in which performance depends on physical appearance and posing ability rather than physical performance. Most of the year bodybuilders spend in the hypertrophy phase, where the aim is to gain and to increase the muscle mass. During the special preparatory period before the competitions bodybuilders aim to reduce their subcutaneous body fat to its minimum to enhance muscular definition. This can be obtained by negative energy balance in the body through restricting the energy intake and increasing energy expenditure. Despite efforts to maintain muscle mass during the preparatory period for competitions, if body energy reserves are limited, bodybuilders may loose muscle mass.


Limited published scientific research is available on bodybuilders during their final preparation to competition. Previous studies in the literature have monitored the diets of a bodybuilder before competitions and showed a significant decrease in body weight and body fat mass and a significant decrease of fat-free mass during the final 3 weeks of the 12-week study period (15). Body composition changes have also been investigated in female bodybuilders (23) and in male bodybuilders (3). However, to the best of our knowledge, no studies have investigated the energy expenditure of a bodybuilder during the preparation for the competition. This would allow the calculation of the energy balance and the anabolic-catabolic hormonal balance, which are critical for maintenance muscle mass during a severe weight-restriction period. It is known from the literature that insulinlike growth factor-1 (IGF-1) and insulin decrease in negative energy balance (18). The behavior of testosterone is not so clear, but in general it decreases (10). However, there is limited knowledge in the literature available to what extent those markers can decrease if negative energy balance is accompanied by limited body fat reserves.


The aim of this study was to determine the simultaneous effect of caloric intake, energy expenditure, and the biochemical parameters that affect the anabolic-catabolic balance in male bodybuilders during their preparation for a target competition. We hypothesized that severe energy restriction and negative energy balance prior to the competition will be associated with a significant decrease in anabolic hormones. Such a decrease may attenuate the ability of bodybuilders to maintain their muscle mass.


Methods

Experimental Approach to the Problem


Minimizing subcutaneous fat content and maintaining the muscle mass are important for bodybuilders before competition. To investigate the effect of energy balance on body composition and anabolic-catabolic hormonal profile, 2 groups of competitive bodybuilders, an energy-restricted group (ERG) and a control group (CG), were used to investigate the energy balance, body composition, and biochemical parameters during the final 11 weeks before competition to achieve negative energy balance. In CG energy intake and training volume were kept unchanged. Body composition was determined by dual-energy X-ray absorptiometry (DXA). Energy intake was determined using a 3-day eating diary (week and weekend days). Energy expenditure was determined by reports of total training volume (resistance and aerobic). Hormonal measurements included circulating concentrations of the anabolic hormones growth hormone (GH), IGF-I, IGF binding protein-3 (IGFBP-3), insulin and, testosterone and the catabolic hormone cortisol.


Subjects


Fourteen male national- and international-level amateur bodybuilders (age 25.4 ± 8.0 years, training experience 7.8 ± 8.7 years) took part in this investigation (Table 1). The subjects were divided into ERG (n = 7) or CG (n = 7). The subjects were not using any drugs or anabolic steroids during the study and during the previous 2 years period and they were free of any disease. The competitors were tested for drugs during recent years and also at the competition for which they were preparing and none of them failed. The study design, purpose, and possible risks were explained to the subjects and written informed consent was obtained from the subjects prior to the investigation. This study was approved by the Ethical Committee of the University of Tartu.

Procedures

The study period was 11 weeks with the national championships at the end of week 11. This competition was the main one for the inclusion criteria to the national team to perform at the European Championships. The ERG was preparing for the championships with the aim of decreasing their body fat content through negative energy balance to build a physique with high muscular definition. They restricted their energy intake and at the same time increased their energy expenditure in an individual way that has been proved as most successful for each subject. CG did not change their eating or training pattern. One subject from ERG was excluded from all the analyses because of his decision not to participate in the championships and to stop the weight reduction. All subjects were tested 3 times-at 11 weeks (T1), 5 weeks (T2), and 3 days (T3) before the championships. The testing procedures were identical during each testing.


Body mass was measured to the nearest 50 g with the medical balance scale (A&D Instruments, Ltd., Abingdon, UK), and the height was measured with the Martin metal anthropometer (GPM, Siber-Hegner, Switzerland) to the nearest 0.1 cm. Body composition was measured using DXA with the Lunar DPX-L total body scanner (Lunar Corporation, Madison, WI, USA) that uses a constant potential X-ray source of 76 kVp and a cerium filter that produces dual-energy peaks of 38 and 62 keV. Soft tissue mass is measured pixel by pixel as a beam of photons penetrating the subjects' body. The DXA procedure has been shown to have precision errors to less than 1.5% for fat mass and lean body mass (13). The device was operated in the medium scan mode (~20 minutes). The calibration of the machine was done daily as suggested by the manufacturer. The subjects were measured while wearing underwear only with their arms at their sides.


The subjects had fasted for at least 10 hours when their fasting blood samples (10 mL) were obtained from the antecubital vein in the upright position at 7:30 to 8:00 am to avoid diurnal changes. The plasma was separated and frozen at -20°C for later analysis. Cortisol, testosterone, IGF-1, IGFBP-3, and growth hormone were analyzed in duplicate on IMMULITE 2000 (DPC, Los Angeles, CA, USA). The interassay and intraassay coefficents of variation were less than 5%. Insulin was determined by means of an immunoradiometric assay (ICN Micromedic System, Horsham, PA, USA) with an intraassay and interassay coefficient of variance of 4.5% and 12.2% at an insulin concentration of 6.6 mU/L, respectively. Glucose was measured by means of the hexokinase/glucose 6-phosphate-dehydrogenase method by using a commercial kit (Boehringer Mannheim, Germany).


During the week of each testing time subjects fulfilled the consecutive 3-day (Thursday, Friday, and Saturday) eating diaries, with the indications of all the consumed food and food supplements. The subjects were instructed on the details needed for accurate recording of the quantity and the characteristics of the food consumed. Based on the diaries the daily energy intake (kcal/day) was calculated as the average of the 3 days. The daily energy expenditure was calculated according to the method of Bouchard et al (4) with the intraclass correlation of 0.96 for mean energy expenditure over 3 days. The subjects also had to report their total training volume (min/week) and the amount of aerobic training and strength training. The daily energy balance was calculated as the difference between the caloric intake and energy expenditure.

Statistical Analyses


Means and SDs were determined. Friedman analyses of variance by ranks were used to examine changes because the data were not normally distributed. The Wilcoxon matched-pairs signed rank test was used where post hoc analysis was relevant. The Wilcoxon matched-pairs signed-ranks test was also used to assess the differences between the measured variables in bodybuilders and control groups. Kendall rank correlation coefficients were used to evaluate associations among different variables of interest. Examining the 2-tailed hypothesis at a power of 0.80, the number of subjects required to demonstrate a significant difference in dependent variables at p <= 0.05 was calculated to be at least 5. The level of significance was set at p <= 0.05.

Results


Total training volume was significantly higher during each week of the study in ERG (Figure 1), with no significant difference in the amount of the total volume of strength training between the 2 groups. Strength training was about 53.5% at T1 and was reduced to about 39% by T3 with a concomitant increase in aerobic training in ERG, whereas in CG the amount of strength training was not changed and was in the range of 65% during the whole study period.

Graphic Figure 1

Nutrient intake, energy expenditure, and energy intake data for the ERG and CG are presented in Table 2. No significant differences were seen in the consumed food components during the study period in both groups; however, a tendency to decrease intake of carbohydrates was found at T3 in the ERG compared to T1. Protein, carbohydrate, and lipid intakes were about 28%, 60%, and 12% of calories consumed in the ERG group during the entire study period, respectively. The respective values were 25%, 60%, and 15% in the CG group. The energy intake of the ERG decreased about 13% from T1 to T3; however, the decrease was not statistically significant. The energy expenditure of the ERG was significantly higher at T2 and T3. The intake of proteins tended to be higher in the ERG compared to CG (p = 0.073) at T1. No more significant differences were found in ERG and CG groups. The increases in energy expenditure and deceases in energy intake resulted in negative energy balance at about 978 kcal/day at T3 in ERG.

Graphic Table 2

The body mass and the body fat percentage of the ERG were significantly decreased during the study period (from 82.9 ± 9.3 to 78.8 ± 8.4 kg and from 9.6 ± 2.3 to 6.5 ± 1.5%, respectively) (Figure 2), whereas no significant changes were observed in the CG. No significant changes were seen in the body mass index, lean body mass, bone mineral component, or lumbar bone values in either ERG or CG (data not shown).

Graphic Figure 2

All hormonal parameters were in the normal range within the study for both groups. At the beginning of the study no significant differences between the biochemical parameters of the 2 groups were observed (Tables 3 and 4). However, there was a tendency (p < 0.1) for a decreased insulin concentration in ERG when compared to the CG. In ERG, IGF-1 and insulin decreased significantly during the 11-week weight-reduction period (p < 0.05). In T2 and T3 testosterone concentration was significantly decreased in ERG when compared to T1. No significant changes were observed in the CG except a significant increase in testosterone concentration from T2 to T3.

Graphic Table 3 Graphic Table 4

There were significant correlations in the change of IGF-I concentration and the changes in insulin (Figure 3), fat mass, lean body mass, and body mass (r = 0.652-0.741; p < 0.05). Changes in insulin concentrations were significantly related to changes in fat mass and lean body mass (r = 0.630-0.725; p < 0.05) (Figure 4). Changes in IGFBP-3 were significantly related to changes to changes in IGF-I and lean body mass (r = 0.689 and r = 0.697, respectively; p < 0.05). No more significant correlations were found between the change in biochemical and anthropometric parameters of the bodybuilders.

Graphic Figure 3 Graphic Figure 4

Discussion


The primary goal of the bodybuilder during the preparation for competition is to reduce subcutaneous fat through energy restriction. The body fat percentage of the subjects decreased from 9.6% to 6.5%, with the lowest individual value being 4.8 %. This is somewhat higher than has been reported in the literature before. However, the methodology of the determination of body fat percentage was also different between the studies. In our study the body fat percentage was measured using the DXA method, whereas previous studies have used the skinfold method and densitometry (3,4) or female subjects (23). A study by Karila et al (10) showed that DXA can be used to monitor body composition changes in relatively lean athletes. Nevertheless, those values together with very high muscle mass are one of the lowest found in the literature and provide excellent conditions to study the organism in the conditions of high constant negative energy balance. The negative energy balance of ERG group was about 200 kcal/day at T1 and reached about 950 kcal/day at T3 3 days before the competitions.


Regulation of the protein anabolism in response to oral feeding involves both stimulation of protein synthesis and a suppression of protein breakdown. These changes are mediated by feeding-induced increases in plasma concentrations of both nutrients and hormones (2). For example, protein balance is influenced by stimulatory (testosterone, IGF-I, insulin) and inhibitory (cortisol) hormones (24). IGF-I and GH activate the protein kinase B (Akt) pathway to increase translational efficiency and protein synthesis, whereas cortisol opposes it (20). The main finding of this study was that anabolic processes were affected negatively, as indicated by the significantly decreased concentrations of insulin and IGF-I and those biochemical changes were significantly related to the changes in the body composition. No significant changes were observed in testosterone and cortisol by the end of the study period. However, testosterone was significantly decreased during the initial energy-restriction period. Furthermore, the values of insulin and IGF-I decreased under the healthy reference value at T3. Fedele et al (8) showed that there is a critical concentration of insulin below which rates of protein synthesis begin to decline in vivo and it is possible that a low but critical concentration of insulin must be available for anabolism after exercise. Furthermore, it has been shown in rats that decreasing the postprandial plasma insulin level below a postabsorptive level resulted in an impairment of protein synthesis compared with postabsorptive protein synthesis (2).


IGF-1 plays an important role in the regulation of somatic growth; metabolism; and cellular proliferation, differentiation, and survival (11) and is responsible for most, but not all, of the anabolic and growth-promoting effects of GH (6). Furthermore, reduced circulating IGF-I levels may indicate negative energy balance, which may lead to attenuated somatic growth (18). Moreover, Nemet et al (14) showed that exercise training can lead to a decrease in IGF-I in weight-stable subjects. IGF-I may also play a compensatory role to facilitate an appropriate anabolic response after resistance exercise in moderately hypoinsulinemic rats (7). However, during the conditions of severe hypoinsulinemia, IGF-I was not significantly different as a result of exercise (8). Therefore, low insulin concentration may hinder the compensatory role of IGF-I. This can be somewhat supported by the significant correlation between the change in insulin and IGF-I concentration found in our study (Figure 3).


Testosterone was decreased slightly but significantly after 5 weeks of energy restriction in ERG at T2 (from 20.3 ± 6.0 to 18.0 ± 6.8 ng/mL) and remained at the same level at T3. In general, weight reduction causes a decrease in plasma testosterone concentration with a very dramatic decrease under rapid weight reduction (10). Decreased testosterone levels were found in wrestlers (18) and judokas (5), which was accompanied by weight loss. These decreases are probably caused by dehydration combined with high-intensity training (5,10,21). However, training of bodybuilders was mainly aerobic, which may have a positive impact on testosterone concentration (12); therefore, after an initial decrease of testosterone at T2 it was possibly maintained by trainings.


It has been reported that bodybuilders must consume a relatively high-protein and low-fat diet (19) to prevent the loss of muscle mass. Amino acid supplementation augments recovery by mechanisms that are unclear but appear to involve increasing protein synthesis and/or reducing protein degradation and reducing muscle damage (17). The protein intake in ERG was about 2.5-2.6 g/kg during the study, which is similar to some previous literature concerning bodybuilders (3,19) and wrestlers (18) and is considered high compared to regular protein needs (1.0-1.2 g/kg) or for athletes (1.8-2.0 g/kg). Efficient recovery protein metabolism is critical to maintaining and promoting the anabolic processes involved in maintenance and development of skeletal muscle mass (1). In our study, however, we found a positive correlation between changes in insulin and IGF-I concentrations and lean body mass. This might indicate the importance of maintaining the concentrations of key anabolic hormones to prevent the loss of muscle mass. On the other side, decreases in fat mass were also significantly related to decreases in insulin and IGF-I, which is actually the purpose in preparation for competition of a bodybuilder. In contrast, it is also known that amino acids (i.e., leucine) can affect anabolic signals unrelated to hormones. Moreover, it has also been found that at insulin concentrations below 5 µU/mL, exogenous amino acids stimulate muscle protein synthesis (9). However, there is evidence that in the absence of insulin, amino acids are able to signal their presence but the effects of insulin and amino acids are maximal in the conditions of high physiological insulin concentrations.


Figure 5 presents the individual data of 2 competitors. Competitor A was able to decrease most of his body fat percentage, whereas competitor B reached the lowest body fat value. Both athletes showed chronically decreased IGF-I and insulin concentrations by the end of the study period. They lost 1.8 kg and 1.5 kg of lean body mass, respectively; with about 1 kg lean body mass loss from T2 to T1. However, both subjects study had relatively high protein intake (i.e., about 28% at the beginning of the study and about 32-33% at the end of the study), which is considered as typical to maintain muscle growth.

Graphic Figure 5

We speculate how an increased protein intake may lead to the loss of muscle mass in severe energy-restricted conditions. In such conditions, a body can not use carbohydrates for energy because their reserves are critical as indicated also by decreased blood glucose values. Body fat reserves are also close to the minimum amount that are needed for survival and can not be used. If we now increase the amount of proteins for additional energy, we force the human body to use proteins for energy and to become accustomed to those conditions. However, there is still severe energy deficiency prevalent in the organism and, as the body gets accustomed to relying on additional energy from proteins, the “available” proteins in muscles may be catabolized and the loss of muscle mass increases. The critical body fat percentage in such conditions might be around 7.0-7.5% from where both insulin and IGF-I decrease under healthy reference values (Figure 5). This mechanism, however, needs further research. Instead of increasing the protein intake in a severe energy deficit, carbohydrates may benefit (22) by helping overcome the energy deficit-induced muscle mass loss. Ingesting carbohydrates with essential amino acids after weight training increased muscle protein synthesis compared to placebo (16). Furthermore, it increased postexercise insulin concentration, which has an impact on anabolic processes.


In conclusion, severe energy restriction to extremely low body energy reserves decreases significantly the concentrations of 3 anabolic pathways despite high protein intake.


Practical Applications


Monitoring the key anabolic hormones can help a bodybuilder to avoid losses in muscle mass during energy-restricted phases before a competition. Very low IGF-I and insulin values will be followed by rapid loss of muscle mass; therefore, if competitions are more than 10 days away, there would be a significant loss of muscle mass. Consumption of more proteins for energy in these conditions is questionable because of the downregulation of anabolic pathways. Stimulating insulin secretion by ingestion of carbohydrates may be helpful because the effects amino acids are higher at high physiological insulin concentration.


References


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2. Balage, M, Sinaud, S, Prod'homme, M, Dardevet, D, Vary, TC, Kimball, SR, Jefferson, LS, and Grizard, J. Amino acids and insulin are both required to regulate assembly of the eIF4E.eIF4G complex in rat skeletal muscle. Am J Physiol Endocrinol Metab 281: 565-574, 2001. [Context Link]


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5. Degoutte, F, Jouanel, P, Bégue, RJ, Colombier, M, Lac, G, Pequignot, JM, and Filaire, E. Food restriction, performance, biochemical, psychological, and endocrine changes in judo athletes. Int J Sports Med 27: 9-18, 2006. [Context Link]


6. Eliakim, A, Nemet, D, and Cooper, DM. Exercise, training and the IGF-I axis. In: The Endocrine System in Sports and Exercise. Kraemer, WJ and Rogol, A, eds. Oxford, UK: Blackwell, 2005. pp. 165-179. [Context Link]


7. Farrell, PA, Fedele, MJ, Vary, TC, Kimball, SR, Lang, CH, and Jefferson, LS. Regulation of protein synthesis after acute exercise in diabetic rats. Am J Physiol Endocrinol Metab 276: 721-727, 1999. [Context Link]


8. Fedele, MJ, Hernandez, JM, Lang, CH, Vary, TC, Kimbal, SR, Jefferson, LS, and Farrell, PA. Severe diabetes prohibits elevations in muscle protein synthesis after acute resistance exercise in rats. J Appl Physiol 88:102-108, 2000. [Context Link]


9. Greenhaff, PL, Karagounis, LG, Peirce, N, Simpson, EJ, Hazell, M, Layfield, R, Wackerhage, H, Smith, K, Atherton, P, Selby, A, and Rennie, MJ. Disassociation between the effects of amino acids and insulin on signaling, ubiquitin ligases, and protein turnover in human muscle. Am J Physiol Endocrinol Metab 295: 595-604, 2008. [Context Link]


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11. Koziris, LP, Hickson, RC, Chatterton, RT Jr, Groseth, RT, Christie, JM, Goldflies, DG, and Unterman, TG. Serum levels of total and free IGF-I and IGFBP-3 are increased and maintained in long-term training. J Appl Physiol 86: 1436-1442, 1999. [Context Link]


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14. Nemet, D, Connolly, PH, Pontello-Pescatello, AM, Rose-Gottron, C, Larson, JK, Galassetti, P, and Cooper, DM. Negative energy balance plays a major role in the IGF-I response to exercise training. J Appl Physiol 96: 276-282, 2004. [Context Link]


15. Newton, LE, Hunter, G, Bamman, M, and Roney, R. Changes in psychological state and self-reported diet during various phases of training in competitional bodybuilders. J Strength Cond Res 7: 153-158, 1993. Request Permissions [Context Link]


16. Rasmussen, BA, Tipton, KD, and Miller, SL. An oral essential amino-acid carbohydrate supplement enhances muscle protein anabolism after resistance exercise. J Appl Physiol 88: 386-392, 2000. [Context Link]


17. Ratamess, NA, Kraemer, WJ, Volek, JS, French, DN, Rubin, MR, Gómez, AL, Newton, RU, and Maresh, CM. The effects of amino acid supplementation on muscular performance during resistance raining overreaching. J Strength Cond Res 17: 250-258, 2003. Request Permissions [Context Link]


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19. Sandoval, WM, Heyward, VH, and Lyons, TM. Comparison of body composition, exercise and nutritional profiles of female and male body builders at competition. J Sports Med 29: 63-70, 1983. [Context Link]


20. Spiering, BA, Kraemer, WJ, Anderson, JM, Armstrong, LE, Nindl, BC, Volek, JS, Judelson, DA, Joseph, M, Vingren, JL, Hatfield, DL, Fragala, MS, Ho, J, and Maresh, CM. Effects of elevated circulation hormones on resistance exercise-induced Akt signaling. Med Sci Sports Exerc 40: 1039-1048. [Context Link]


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24. Volek, JS, Sharman, MJ, Love, DM, Avery, NG, Cómez, AL, Scheet, TP, and Kraemer, WJ. Body composition and hormonal responses to carbohydrate restricted diet. Metabolism 51: 864-870, 2002. [Context Link]


Key Words: weight restriction; energy intake; energy expenditure; anabolism; muscle mass

 

[tim290280]

I have both of these pdf's if anyone wants to see the pretty graphs.

 

[Cork]

Oh graphs! You have my e-mail still?

 

[tim290280]

^^ Easiest just to PM me again. I've probably got it on one of these computers....... probably.

 

[philosopher]

Searched for something and this thread popped up. Worth a bump if you ask me!

 

[tim290280]

I have been quoting this particular study for years and for some reason could never find it again. Until now.

Clinical Biomechanics
Volume 16, Issue 5, June 2001, Pages 424-430
Patellofemoral joint kinetics during squatting in collegiate women athletes
George J. Salem, and Christopher M. Powers

Musculoskeletal Biomechanics Research Laboratory, Department of Biokinesiology and Physical Therapy, University of Southern California, 1540 E. Alcazar Street, CHP-155, Los Angeles, CA 90033, USA

Received 6 September 2000; accepted 13 February 2001 Available online 30 May 2001.

Abstract
Objective. To characterize the biomechanics of the patellofemoral joint during squatting in collegiate women athletes.

Design. Repeated measures experimental design.

Background. Although squatting exercises are required components of most intercollegiate resistance-training programs and are commonly performed during rehabilitation, the effects of various squatting depths on patellofemoral joint stress have not been quantified.

Methods. Anthropometric data, three-dimensional knee kinematics, and ground reaction forces were used to calculate the knee extensor moment (inverse dynamics approach) in five intercollegiate female athletes during squatting exercise at three different depths (approximately 70?, 90? and 110? of knee flexion). A biomechanical model of the patellofemoral joint was used to quantify the patellofemoral joint reaction force and patellofemoral joint stress during each trial.

Results. Peak knee extensor moment, patellofemoral joint reaction force and patellofemoral joint stress did not vary significantly between the three squatting trials.

Conclusions. Squatting from 70? to 110? of knee flexion had little effect on patellofemoral joint kinetics. The relative constancy of the patellofemoral joint reaction force and joint stress appeared to be related to a consistent knee extensor moment produced across the three squatting depths.
Relevance

The results of this study do not support the premise that squatting to 110? places greater stress on the patellofemoral joint than squatting to 70?. These findings may have implications with respect to the safe design of athletic training regimens and rehabilitation programs.

Author Keywords: Patellofemoral joint; Patellofemoral joint reaction force; Knee extensor moment; Patellofemoral joint stress; Squatting

So squat deep you pussies!!!

 

[Cork]

And here I thought there would actually be harder forces on the knee at the 70 degree angle. I was under the impression that reversing the weight at that shallow depth would cause shearing forces towards the knee. Maybe I'm getting my forces confused, and this study didn't take into account shearing. Tim, have you heard anything about there being more forces applied to the knee if the squat never hits parallel?

 

[tim290280]

And here I thought there would actually be harder forces on the knee at the 70 degree angle. I was under the impression that reversing the weight at that shallow depth would cause shearing forces towards the knee. Maybe I'm getting my forces confused, and this study didn't take into account shearing. Tim, have you heard anything about there being more forces applied to the knee if the squat never hits parallel?

Yes. I created a thread about squatting depth a while ago that covered it.

The other thing this paper didn't cover is the cartilage stress in the knee bone surfaces. I cover that in that thread as well. From memory you can do a 3 or 4x BW squat before it is a concern for depth. But start jumping and you meet that limit very easily.