Little things matter when it comes to squeaking extra performance out of your workout. Tiny adjustments can be the difference between two extra reps and five. Small changes to stance can dramatically decrease your chance of injury. And paying close attention to the position of your wrist can yield huge dividends in a variety of fitness arenas.
True for machines and free weights alike (but especially for free weights), the wrist is usually meant to be inconsequential... In other words, it should act as an extension of your arm. That means keeping it in a perfectly straight line you’re your forearm and knuckles. Unless the particular exercise calls for you to repeatedly bend or flex your wrist, keep it straight. Failing to do so during upper body workouts can transfer the workload to forearms and grip muscles rather than biceps, triceps and chest, robbing you of important reps for those muscle groups. During pushups, hands should be flat on the floor at all times, never using palms or fingertips to assist in the motion (better yet, work towards pushups on your knuckles... you’ll be surprised what a challenge it is).
You wouldn’t think it, but your wrists can cost you some valuable time and distance in your cardio conditioning. However, instead of how your wrist is positioned in relation to your arm, it is more about how high or low your wrist comes during your running motion. Running is a lower-body muscle activity... so any energy you expend with other parts of the body is just stealing from your legs as well as your heart and lungs. Control is the name of the game here. Never letting your wrists come above chest level or any further back than your hip bones will ensure your arms are minimally engaged, your shoulders relaxed and energy is going where it should.
Nearly anyone that’s spent more than a few hours in the pool knows how important form is to stroke efficiency. Just a few millimeters of wrist tilt or rotation in any direction changes the way water flows over the hand and arm, which ultimately effects the speed of the swimmer in the water. Generally, strong, straight wrists are preferred so as to lengthen the arm, providing more push against the water. Tilt should be as flat as possible when pushing water, and as narrow as possible when entering the water or finishing a stroke. “Scooping” is a popular reference to how swimmers cup their hands to increase resistance against the water and achieve forward motion, but it is important that the swimmer not bend his or her wrists to create an exaggerated (and ineffective) scoop.