Single-arm hammer curl. Hold a dumbbell in each hand and turn your palms towards your body. Hug the elbows in toward your waist. Curl up the right arm first, then lower it down.

The hand, developed at Switzerland’s EPFL, can detach from an arm, crawl around on its own, grab small objects, and bring them back before reattaching itself.

Hold upper right arm with left hand to deepen the stretch. Hold for 20 to 30 seconds. Then repeat on opposite side. 2. Upright Dumbbell Row. Why it works: This exercise can power your arm swing by ...

With your left hand, gently pull back the fingers of your right hand. Hold this stretch for at least 3 deep breaths. Let your right wrist go limp, the fingers pointing down.