Sure dumbbells enhance strength-training workouts, but your body weight can provide just as much resistance. Even if you’re not Einstein or Newton, you can understand the physics behind these mechanical methods for taxing your muscles.
Elongate: Gravity’s force on your body increases with distance. Think of lifting a broomstick from either end vs. from the center. Extending your body makes it work harder to move. Stretch your arms over your head during sit-ups or squats to engage muscles.
Add distance: Stepping up 2 stairs requires more effort than stepping up 1. The same is true for any exercise. Put more distance between you and the ground, and you’ll feel the burn. Try push-ups with your legs on a chair. Or increase intensity by adding mini-motions within the full motion, like lowering down on a lunge, raising a quarter of the way, then returning down before coming back to start mode.
Pause: When your muscles act, you add momentum — helping propel you back into your original position. But you can discharge that “elastic” energy and induce more muscle involvement by holding a position for 4 seconds. Squat down, pause, then push back into position. Or challenge yourself to jump out of the dead stance.