We have a strange relationship with gravity. It can be good or bad depending on how you deal with it. For example, sky diving with a parachute, you’ll have a good time. Sky diving without a parachute, you’ll have a bad time. The same goes with exercise. If you start lifting weights without considering gravity, you’re probably not going to reach the goals you had in mind.
All too often I see people performing exercises that are completely useless due to the way they oppose gravity. This just sets people up for injuries and won’t really put their muscles in the tension needed to get them to grow strong. So let’s do a quick basic physics lesson to see why these exercises don’t work:
Gravity is a linear force. It only goes down, perpendicular with the ground. When you lift a weight, the reason it is heavy is because you are moving it against gravity. In other words, you are moving the weight parallel or in line with the force of gravity’s vector. Now what happens when you move the weight perpendicular to gravity, or maybe not exactly in line with gravity? Well, in essence, you are taking out the weight component of the movement. This means that you are no longer putting tension on the muscles needed to make that movement. For example, let’s take the bench press. You lay down and push the weight up, which is opposing gravity/parallel to the force vector. This requires work from your triceps and chest so that your shoulders and arms can move the weight up. Now let’s say we do the same motion with the same weight, but standing up and pushing forward (a punching motion). You have now eliminated the gravity component of the weight, so now your triceps and chest are no longer pushing against the weight. Now it is just your shoulders straining to keep your arms raised and your forearms contracting to keep the weights in your hands. You are in essence performing a front deltoid raise at the end of the movement. This wouldn’t give you the chest workout you’re looking for; it would only strain your shoulders and set you up for injury. So it doesn’t make sense to do this motion to work out your chest, now does it?
While this example may seem obvious, many people still make the mistake of performing exercises that aren’t really working with force of gravity. Here are a few examples:
- Punching with Dumbbells: the only muscle really working out here are your deltoids at the very end of the movement. But your shoulder joint is put under a lot of tension because of the torque experienced from having the weight so far from your body. This in combination with an internally rotated arm (palms down) will make you more likely to experience shoulder injuries. If you want to strengthen your shoulders, triceps, and chest (the main muscles utilized in a punch) use exercises that actually strengthen those muscles, like:
- Bench Press
- Close-grip dumbbell press
- Overhead press
- Tricep Kickbacks: in this exercise, your triceps are only working at the very end of the motion. And this is only true if your shoulders are extended back far enough to allow your arm to extend enough to bring the weight parallel to gravity. Instead, lay on your back and do skull crushers. You now move the weight parallel to gravity in the middle of the motion, and have to exceed this position to reach the end of the motion, putting your triceps under the most force for the longest amount of time. Or just use cables, so the same tension is applied at all positions in the movement.
- Internal/External Shoulder Rotations with Dumbbells while Standing: Example (but with dumbbells). Again, same thing. You’re rotating the weight back and forth perpendicular to gravity; your rotator cuff muscles aren’t working here even though that is the intention of the exercise. Your biceps are the only thing being used here to just keep your elbow flexed while holding the weight. Stop wasting your time with this. Lay down on your side and perform the same motion, or use cables (as in the photo). This will strengthen your rotator cuff muscles to help provide a more stable shoulder.
- Rolling your Shoulders while Shrugging: Your upper trapezius muscle works by shrugging your shoulder, i.e. raising your scapula upwards. Protracting and retracting your shoulders while standing only puts your shoulders in more unstable positions (specifically when protracted with a weight), increasing your risk for injury. To increase the workload safely, add weight and shrug directly upwards with your arms directly at your sides or with your scapula slightly retracted (more stable). This allows your trapezius to work directly against gravity without straining your shoulder.
There are plenty of other exercises that fall under the same mistake. But the main point here is that you must always consider the motion used in an exercise and it’s relationship with gravity. Or just use cables to eliminate the component of gravity entirely. By performing exercises that put your muscles safely under the right kind of tension, you can get the strength and muscle growth needed to achieve your goals.