You can’t stop father time, but you can reduce to some extent the effects he has on your body. Perhaps the biggest effect is that your once-firm skin loses its elasticity and tends to hang under your chin and at the tops of your arms. Exercise cannot make your skin bounce back, but building muscle creates a greater area for the skin to stretch over. While you may not look as firm as you did in your twenties, exercise might get you back into sleeveless tops. And even if it doesn’t totally firm your arms, strong upper arms will allow you to continue doing everyday tasks, like lifting, without injury
The main muscles of your upper arms are the biceps in the front and the triceps at the back. The former works when you bend your elbow; the latter when you straighten it. Since you’re more likely to notice sagging skin when you raise your arms, you may tend to concentrate on your triceps. In fact, it’s simply gravity that pulls the skin down. You really need to build the entire upper arm to make skin appear firmer and maintain muscle balance to avoid injury. For each exercise, do one set of 10 to 15 repetitions. Choose a resistance with which 10 reps is tough at first. If you’re just starting to exercise in your 60s, you may have to start at a very low resistance. When you can do 15 reps easily, increase the weight or move on to a more challenging exercise.