Make Any Bodyweight Exercise More Challenging–Without Adding Weights

This article originally appeared on Womens Running

If you’re looking for home workouts without equipment, but worried about the results, we’ve got good news: It is possible to build muscle without weights. In fact, all bodyweight exercises can be just as challenging (and effective) as a pullup. You just have to know how to tailor them to your fitness level--and then adapt them when that level changes.

And it turns out that bodyweight exercises are good for more than just building muscle. Recent research has even found that bodyweight exercises–when performed at a “challenging pace”–can improve cardiorespiratory fitness.

The best trainers and strength coaches know how to tailor bodyweight exercises to their own fitness level--and then adapt them when that level changes. Steal their science-backed rules to get a more effective workout sans equipment.

Build Muscle By Following These 5 Laws of Bodyweight Workouts

Apply any one of these five laws of physics to your regular bodyweight strength exercises to make them even more effective.

Law #1: To get leaner, be longer

The science: As you increase the distance between the point of force (your target muscles) and the end of the object you're trying to lift (your body), you decrease your mechanical advantage. Translation: The longer your body, the weaker you become and the more your muscles have to work. This is the major difference between "girly" pushups and regular ones. When you get off your knees your core muscles have to work a whole lot harder to support more of your body weight.

Apply it: Raise your hands above your head so your arms are straight and in line with your body during lunges, squats, crunches, and situps. Too hard? Split the distance by putting your hands behind your head.

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Law #2: Take The Spring Out Of Your Step

The science: When you lower your body during any exercise, your muscles build up what's known as elastic energy. It works like a coiled spring: The elasticity allows you to bounce back to the starting position and reduces the amount of work your muscles have to do.

Apply it: Take a 4-second pause at the bottom position of any exercise. That's how long it takes to discharge all the elastic energy of a muscle. Without the bounce, you'll force your body to recruit more muscle fibers to get you moving again.

Law #3: Go The Distance

The science: Physics defines work as force (here, that's how much you weigh) times distance. Since you can't increase force beyond your own body weight without an external load (like a dumbbell), the only way to work more is to move farther during each rep.

Apply it: For bodyweight exercises--such as lunges, pushups, and sit-ups--your range of motion ends at the floor. The solution: Move the floor farther away. Try placing your front or back foot on a step when doing lunges, or position your hands or feet on a step when doing pushups.

Law #4: Add a Twist

The science: Human movement happens on three geometric planes: the sagittal plane (front-back and up-down), the frontal plane (side to side), and the transverse plane (rotation). Many common bodyweight exercises--like squats and side lunges--are performed on the first two planes. But we rarely train our bodies on the transverse plane, despite using it all the time in our everyday lives: when walking, for example.

Apply it: Simply rotate your torso to the right or left in exercises such as lunges, situps, and pushups; you'll fully engage your core in addition to the muscles those moves are intended to target.

Law #5: Get Off The Floor

The science: The less of an object's surface area (in this case, your body) that touches a solid base (the floor), the less stable that object is. Fortunately, we have a built-in stabilization system: our muscles. So knocking yourself a little off kilter makes you exercise harder and enlists more muscles.

Apply it: Hold one foot in the air during pushups, squats, and planks.

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