# The Physics Of A TRX (or Suspension Trainer) Row - How Much Am I Lifting?

I'm not sure how to solve this problem. It looks like a sum of torque moments issue on one level, much like a push up. But with the push up, for the most part I'm only dealing with vertical components.

I've two questions;

• is the amount of X component applied at the foot simply equal to the sine of the angle between my leg and a vertical line? Assuming we have enough of a friction coefficient to stop me sliding forward? Which would then be equal to whatever weight my feet had in them x said coefficient (0.6 or whatever)?

• And then does the increase in X component affect the amount of force in my hands? Or is the increase in load taken by the hands as we get more horizontal simply due to the distance the COM is away from the axis of the foot?

This will tell you how is the tension $$T$$, normal force $$N$$ and foot friction $$F$$ depend on the weight $$W$$ as well as the ankle torque $$M$$.
This should answer your question on what goes into $$F$$, and its relation to $$T$$.