When you lift, two forces that are at odds with each other are always trying to take control of your joints. Gravity pulls your load down, which is external torque. On the other hand, your muscles contract to fight this, which is internal torque. As you move, the angles of your joints change, which means that the relationship between these forces is always changing. You can train smarter, fix weak spots, and protect your joints by understanding how they work together.
There are two torques that are fighting at any given time. The load and gravity are what make external joint torque. They try to turn your joints in one direction. When you tighten your muscles to stop that rotation, you get internal joint torque.
The moment arm tells you how hard a position really is. Because a longer moment arm means torque needs to be bigger, joint angle is much more important than most lifters think.
Through joint mechanics, these forces are always working against each other. Your muscles create internal torque by pulling on bones at certain angles. The strength of each muscle depends on its muscle moment arm, which is the distance between the joint axis and the muscle's line of pull that is perpendicular to it.
The resistance curve changes as you move through a lift. This means that the external force changes as you move through the range of motion. Your muscles have to keep changing the amount of internal force they put out to keep up with the changing needs at every joint angle.
Keep an eye out for these signs: you slow down a lot before lockout, you fall forward when you're loaded, or you feel drained all at once. These aren't just random flaws. They show that force generation is breaking down right where torque demands from the outside are highest.
Once you know these patterns, you can focus your training on those angles, build up your internal torque capacity, and stop losing reps because of biomechanical issues you didn't know were affecting your lifts.
Use what you've learned. If your lower back curves at the bottom of a squat, it means that the external torque at the hip is stronger than your internal torque. You move the weight back to the muscles after fixing the position.
When you have cleaner mechanics at high-torque joint angles, you put more tension on your target muscles, which helps them grow. Not only is better practice safer, but it also works better too.
What Is Joint Torque and Why Does It Matter for Lifters?
Every rep you do in the gym is a fight between forces that rotate. You can think of torque as a rotational force working around a joint. In resistance training, it controls all movements. The equation for torque is simple: torque is equal to force times the moment arm, which is the distance between the joint axis and the line of force that is perpendicular to it.There are two torques that are fighting at any given time. The load and gravity are what make external joint torque. They try to turn your joints in one direction. When you tighten your muscles to stop that rotation, you get internal joint torque.
The moment arm tells you how hard a position really is. Because a longer moment arm means torque needs to be bigger, joint angle is much more important than most lifters think.
Internal vs. External Joint Torque: The Core Difference
There are two opposing rotational forces at work as soon as you hold a barbell and lower it toward your chest. When you put weight on something, gravity pulls it down, which creates rotational stress around your joints. When your muscles contract to fight off and manage that stress, you get internal torque.Through joint mechanics, these forces are always working against each other. Your muscles create internal torque by pulling on bones at certain angles. The strength of each muscle depends on its muscle moment arm, which is the distance between the joint axis and the muscle's line of pull that is perpendicular to it.
The resistance curve changes as you move through a lift. This means that the external force changes as you move through the range of motion. Your muscles have to keep changing the amount of internal force they put out to keep up with the changing needs at every joint angle.
Where Joint Torque Actually Goes in the Squat and Deadlift
The squat and deadlift are two workouts that work a lot of different muscles at the same time. As you move through the range of motion in both lifts, the external torque changes all the time. Hip and knee torque demands increase at the same time at the bottom of a squat. To make enough internal torque, you need to use a lot of muscle power from your glutes, quads, and spinal erectors. When you first start the deadlift, and your body is flat on the ground, hip external torque is the most important force. The moment arm gets shorter as you rise, which lowers the torque needs. During these moves, your muscles don't work out the same amount. Finding the highest point of external torque tells you exactly where your internal torque production needs to be at its highest. This lets you focus on weak spots and train those positions more specifically.
How to Spot When External Joint Torque Is Controlling Your Lift
Sometimes external torque isn't clear, but your body will let you know by showing you repeated failure patterns. If you're missing reps at the same joint angle, the external torque is likely stronger than the internal torque at that point. That's where the moment arms are longest and the mechanical tension is highest, which makes your muscles work harder when they're not ready to.Keep an eye out for these signs: you slow down a lot before lockout, you fall forward when you're loaded, or you feel drained all at once. These aren't just random flaws. They show that force generation is breaking down right where torque demands from the outside are highest.
Once you know these patterns, you can focus your training on those angles, build up your internal torque capacity, and stop losing reps because of biomechanical issues you didn't know were affecting your lifts.
Use Joint Torque Cues to Clean Up Technique and Protect Your Joints
If you know where the external torque peaks in a movement, you can tell right away where bad technique starts to become dangerous. At a certain joint position, when external torque goes up, your muscles have to put out the most internal torque they can. You're putting stress on passive structures like ligaments and cartilage instead of contractile tissue if your technique isn't good enough there.Use what you've learned. If your lower back curves at the bottom of a squat, it means that the external torque at the hip is stronger than your internal torque. You move the weight back to the muscles after fixing the position.
When you have cleaner mechanics at high-torque joint angles, you put more tension on your target muscles, which helps them grow. Not only is better practice safer, but it also works better too.
