Test the Bench
Press your thumb into the bench before lifting. "If you can feel the wood, find another bench," says Ken Kinakin, a chiropractor in Canada and founder of the Society of Weight-Training Injury Specialists. Hard benches can cause T4 syndrome—a misalignment of your thoracic spine that affects the nerve function of your arm, weakening it. 


Strengthen Your Core
Don't be afraid of situps. We've changed our tune on these, and here's why: Situps increase your range of motion, which makes your abdominals work harder and longer. (Doing crunches on a Swiss ball or with a rolled-up towel under your lower back has a similar effect.) Just avoid situps with anchored feet, which can hurt your lower back.



Grow Muscle, Save Time
Keep your weight workouts under an hour. After 60 minutes, your body starts producing more of the stress hormone cortisol, which can have a testosterone-blocking, muscle-wasting effect.