Swinging
Lifting weights is built of two parts, the concentric and eccentric, or the contract and stretch. If you’re swinging into the move to build momentum then you’re not able to control the eccentric phase and you sacrifice results. You also risk injury when you’re not in control. Use a one second count on the concentric movement, and four on the eccentric.
Not swinging
In contrast, not using your arms while on a cardio machine like a treadmill or elliptical means you’re missing out on an additional calorie burn. If you need the rails to help stabilize yourself, then just use them as a guide and keep your fingertips lightly on them. If you’re still having trouble, try lowering the incline or slowing your pace.
Not fully extending
This is solely to do with pushups, but is immensely important. If you’re not completing your pushups by lowering your chest all the way to the ground, then you’re not getting an effective workout. To properly engage all the muscles involved in pushups, you need to hold your body in plank position and then contract your arm muscles to descend your chest to the ground.
Speed
Paying attention to how fast or slow you should be going in each move will help ensure you are achieving the most effective workout possible. Some movements demand a slower, more concentrated pace that ensures you’re able to hold the correct form and contract the correct muscles. Speeding through lunges will get your reps done, but without proper form your muscles won’t be getting strong as quickly.
Watch your back
Many compound moves require that you brace your core and engage your back muscles. If you’re slouching, arching, sinking or even putting pressure on your back you could be jeopardizing your progress, and be at risk of injury. If not engaged properly, you’re causing not only your back muscles to miss out on a workout, but also the surrounding muscles that are part of the movement.