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And is way better for your shoulder health.
Agree.
Infront is alot better for your rotator manchett
And is way better for your shoulder health.
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.
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.
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.
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.
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.
Timbo said: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.
^^ 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.
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
Yes. I created a thread about squatting depth a while ago that covered it.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?