When you do light calf raises with your knees straight, the exercise mainly works the outer and back parts of your lower leg muscles while leaving the deeper calf and shin muscles mostly untouched. This shows that keeping your knees straight during light resistance training specifically targets the more superficial muscles in your calves.

Our current analysis shows that light calf raises performed with straight knees appear to target the outer and back parts of the lower leg while leaving deeper muscles mostly inactive. The evidence we have reviewed leans toward the idea that this specific movement focuses on the more superficial muscles, which are the ones located closer to the surface of your skin. We analyzed the available research and found that 27 studies support, 0 studies refute this pattern. When we look at what we have gathered so far, the data suggests that keeping your knees straight during low-intensity calf raises directs the effort toward the outer and back sections of your lower leg [1]. This means the deeper calf muscles and the muscles in your shin do not get much stimulation during this exact version of the exercise. We want to be clear that our current analysis is based on the evidence we have reviewed up to this point, and our understanding continues to improve as more information becomes available. The evidence we have reviewed leans toward the conclusion that straight-knee, light resistance training specifically targets the more superficial muscles in your calves. If you are trying to build strength in your lower legs, this movement may be a good choice if your goal is to focus on the outer and back areas. You can pair it with other exercises that bend your knees or use heavier weights to make sure you are also engaging the deeper muscles. We will keep tracking new findings to give you the most accurate picture as time goes on.