Blood flow restriction during lower body resistance exercise in young women is associated with a greater increase in heart rate and cardiac output during exercise compared to upper body resistance exercise with the same restriction, indicating higher cardiovascular demand from larger muscle groups.

When large muscle groups like the legs are exercised with restricted blood flow, they produce more waste products like lactic acid and hydrogen ions. These chemicals activate nerves in the muscles that signal the brain to increase heart rate and pumping force, while also narrowing blood vessels in other parts of the body. This forces the heart to work harder to deliver oxygen, resulting in a bigger rise in heart rate and blood flow compared to exercising smaller muscles like the arms under the same restriction.