It can be tempting to skip “leg day” when the results from your upper body and core workouts are more noticeable. But it’s essential to work all muscle groups for your overall health and well-being, says Marquese Stallworth, EP-C, a Piedmont exercise physiologist.

When it comes to leg day, Kay says it should be skipped if "you are experiencing excessive joint pain, muscle soreness or currently sick." In these instances, she recommends that you either take an extra rest day, skip leg day for the week, or focus on "doing only gentle mobility work."

If you skip leg day, it’s not like your upper body will be enormous and your legs will look like pencils. However, when an athlete trains only their upper body muscles and never their legs, you can tell. There’s less muscle mass and definition, and the upper and lower halves just don’t match.