How Your Body Shape Affects Your Weight Lifting Shape: a Physics Lesson

You have heard all the cues, from holding your chest up to pushing your knees out. You are sure that you are doing everything right , but you still feel wrong. If this sounds like you are in the gym, it may be because you are not using the shape that suits your body.

When it comes to lifting weights, there are two main factors to consider – balance and points that you may have studied in physics school. You are technically balanced when your center of gravity (most of your mass) is above your base (where you connect to the ground). When it comes to the gym, the importance of this is pretty obvious: it will be difficult for you to make any progress if you roll over every time you lift weights.

Moments are a less straightforward concept. Unlike the name, moments in physics have nothing to do with time at all. Instead, they are a measure of the force of rotation about an axis . For example: think about how a wrench works. If the bolt is firmly pressed against the nail, it is nearly impossible to unscrew it with your bare hands, no matter how hard you try. But with a wrench, you won’t need that much grease for your elbows. Just apply a little force to the end of the handle and it will begin to twist off. This is due to the moments: when using a wrench, the force you apply is much further from the bolt and screw ( axle ), so there is a large turning force ( moment ), which greatly simplifies the work.

When it comes to lifting weights, the goal is to minimize moments around all of the respective joints while keeping the center of gravity above the base to stay stable. After all, gravity is difficult to deal with, not to mention biomechanical inefficiency. This is where your individual anatomy comes in.

How you shorten the moments around your joints depends on the length of your limbs and the relative strength of your muscles. For example, let’s look at squats. Squats involve two main axes – the hip and knee joints, as well as two main levers – the hips and trunk. If you have long legs and a short torso, the problems you will face will be very different from those faced by someone with short legs and a long torso. To understand why, let’s look at an illustration (extremely primitive and highly exaggerated):

As you can see in the image, a person with long legs and a short torso has to bend a lot more in order to keep their center of gravity above their base. Because of this, they have to grapple with more important points and need to work much harder to avoid tipping forward. On the other hand, a person with shorter hips and a longer torso will find it easier to stay upright since their body parts do not move too far from the center of gravity.

In addition, other factors affect the shape. First, there is the problem of injuries. If you are recovering from an injury or have a sensitive area, reshaping may be your best option to avoid aggravating the area. There is also the issue of mobility : you have to make concessions if you are too inflexible or too weak to get in the right position.

How to adapt the shape to your body

The point is not that you should give up if you were genetically cursed (blessed?) With long legs or suboptimal leverage. Instead, understand that there is no one-size-fits-all approach to working out in the gym. The “correct” method is one that is comfortable for you and allows you to minimize the effort and energy expended in moving the weight where it should go.

With that in mind, here are some simple squat and deadlift modifications – arguably the most important and most challenging exercises – that can help you start your progress in the right direction:


  • If you have long legs and find it difficult to keep your torso upright, or if you have problems with the mobility of your ankles, try widening the position of your foot. This reduces the distance your hips need to move forward, so you don’t have to lean forward that much.
  • If you are still having problems after squats with wide stances, try the squats with a low bar. This is when you position the bar just above your shoulder blades. Providing your shoulders are flexible enough, the barbell position will help reduce torque around the hip joint and engage more back muscles.
  • If you suffer from knee pain, avoid squats with a high barbell in a narrow stance, as they put a lot of stress on the knee.


  • If you don’t have the mobility to reach the bar, lift the weight by placing the barbell on multiple weights, or try the sumo deadlift.
  • If you have shorter arms or a longer torso, you can also try sumo deadlifts – you start closer to the ground and you don’t need to move your weight that far.
  • If you’re recovering from a back injury, try the barbell deadlift. They create less turning force on your back, so your back is less vulnerable to injury.

The explanations I’ve given are pretty basic, but hopefully give you a better idea of ​​how physics affects shape. If you’re curious and want to know more, Eric Cressy has a great breakdown of deadlift options , and ExRx also has adetailed squat analysis . They may be a little tight, but this is interesting and the principles can be carried over to other exercises.

Image of Berry .

Vitals is a new blog from Lifehacker dedicated to health and fitness. Follow us on Twitter here .


Leave a Reply