Fitness Rules: The Lean-Body Laws

Apply these scientific principles to your workout and tone up faster

August 6, 2012
Munetaka Tokuyama

Even if you snored your way through physics class, once you realize that all those textbook equations can be used to sculpt a toned body, science suddenly becomes sooo much more interesting.

Your body is a highly technical machine, governed by the same laws of science and principles of physics that make an apple drop from a tree or a seesaw teeter up and down. With simple tweaks to your fitness routine—like how you position your hands and feet during an exercise—you can get better results in less time. The best part? You don't have to be Sir Isaac Newton to ace this lesson. Here, five simple concepts to put into motion.


1. Shake It Up
Ever wonder why a single-leg squat is so much harder than a regular one? It's the biomechanics of stability. The less an object's surface area (in this case, your feet) touches a solid base (the floor), the less stable the object is, says Stephen Stanley, a kinesiologist at Siliconcoach, a company that specializes in movement-analysis technology. You can also ditch the solid base altogether and do moves on an unstable surface, which makes your body work harder to produce faster results.


2. Go Against the Flow
Dumbbells, resistance bands, even water—they're all ways to apply external force to your workload, making any sweat session more challenging. Resistance is also what gets you results: The added stress on your body encourages muscle growth, which helps increase your metabolism and blast fat. But there are two subtle forces you may not have considered: wind and incline. It's always more difficult to ride your bike into a headwind or make your way through a trail run rather than jog on a flat treadmill. That's because your body has to use more energy to overcome resistance and requires more calories, says Stanley. Exercising in these conditions is a simple way to increase the intensity of an otherwise ordinary workout.

APPLY IT: On windy days, unless you're planning a run or ride longer than 90 minutes, head out going into the breeze. If you don't have trails or hills nearby, or if you have an indoor run planned, set your tread mil I to at least a 1 to 2 percent incline to more closely mimic the demands of outdoor running.

3. Leverage Yourself
Your muscles, bones, and joints act as a system of levers, working together to allow you to move heavy or light loads. As you increase the distance between the object you're trying to lift and the joint (the pivot point or fulcrum) that's moving, your muscles must generate more force, which decreases your mechanical advantage, says Stanley. Translation: Your muscles are put at a disadvantage, so they have to work harder. Which makes this a no-brainer strategy if you're looking to get stronger and leaner without spending more time at the gym.

APPLY IT: Exercises like lateral raises or side leg lifts require the load to be at a greater distance from the fulcrum (your shoulder and hip joint, in these cases). Or raise your arms overhead during squats, lunges, and even weighted crunches. Too hard? Split the distance by bringing the weight to your shoulders, rather than above your head or down at your sides.

4. Learn to Twist
Most exercises happen in one of two geometric planes—the sagittal (up and down, and front to back) and the frontal (side to side), says certified strength and conditioning specialist Andre Farnell, owner of Better Body Expert Fitness Solutions in New York City. But there's a third plane, called the transverse—the realm of rotational movement. Adding motion in that third plane engages your core, which increases the number of muscles recruited and therefore calories burned. And these movements are more in tune with how we naturally function. "When we walk and do everyday activities, we use all three planes," says Farnell. "But most Americans neglect the transverse plane in the gym." So working this principle into your routine will give you strong, show-off-worthy abs—plus, it will make daily tasks like hauling groceries feel easier.

APPLY IT: Rotate your body to the right or left in exercises such as the walking lunge and situp, or bring your knee across your body during moves like the mountain climber.

5. Improve Your Stride
The physics of running works like this: When your foot hits the road (or treadmill), you apply a force to the ground, which responds with an equal and opposite force (Newton's third law of dynamics), helping to propel you forward. As you speed up, either the length of your stride or your step rate—how frequently your foot hits the ground—naturally increases. That's thanks to your own personal biomechanics. Working to improve your running stride can help make every run feel less taxing, which can help you increase both speed and distance while helping avoid injury. Drive yourself forward from your hips by pushing off your back leg rather than overextending your front leg.

APPLY IT: Research has shown that elite runners have an optimum step rate of 180 or more foot strikes per minute. To improve your running, try increasing your step rate by 5 to 10 percent. To find your rate, count how many times your feet hit the ground while running at an easy pace for 30 seconds. Double that number for your step rate. Want to improve it? Fill your playlist with songs that have 180 beats per minute—running to the beat will help you quicken your cadence.