Isotonic movement is a type of muscle contraction. Most exercise regimens include isotonic exercises, many of which you’re probably already familiar with: squats, push-ups, pull-ups, bench presses, and deadlifts.
The term “isotonic” comes from ancient Greek and roughly translates into “same tension” or “same tone.” “This means isotonic exercise keeps the muscles at the same tension throughout the movement,” says Jonathan Sabar, ACE, NCSF, ISSA, a certified trainer and owner of Defy! Fitness in Broomfield, Colorado.
“Most exercises we think of for working out are isotonic — moving your body or an external weight through a range of motion deliberately,” Sabar explains.
This differs from isometric (“same length”) exercise, in which the muscle works against a force without the muscle changing length (“static”). It’s also different form isokinetic (“same speed”) exercise, where the rate of movement is constant. Isokinetic exercise “requires specialized equipment to keep the load moving at a constant rate, regardless of the force applied,” says Sabar.
The Advantages of Isotonic Training
When exercising, it's important to know why you're doing what you're doing and how to do it safely. Isotonic exercises are popular because they don’t require special equipment or anything you can’t find in a typical gym. Additionally, many isotonic exercises, like squats and push-ups, are natural and intuitive for most people. This means they translate well into movements humans perform daily outside of the gym. Isotonic movements also work the entire range-of-motion of a joint.
While isotonic exercises are pretty intuitive, most people know squat about squats, says Sabar. “Push-ups are an awesome exercise nobody ever teaches. They just say ‘Drop and give me 10’,” he says.
To get the most out of your exercise regimen and get to peak muscle performance, read Sabar’s tips for perfecting the push-up and the squat below.
- Make sure your knees are tracking (in line) with your toes. If your knees tend to buckle inward, rotate your feet outward, or ‘spread the floor’ with your feet.
- Don't flatten your back, but don't exaggerate a back arch. Use your glutes, abs, back, and hip flexors to lock your ribcage and your back into a neutral curve.
- As you begin each squat, keep your glutes tight enough that your hip flexors literally pull you into a squat. This keeps your hips active.
- Push through the entire arch of your foot. Don't rock forward to the ball of your foot.
- The range of motion of a full squat bottoms out when the crease of your hip is below the top of your knee.
- Initiate the drive up from the bottom from your hips, not your knees. Start the movement by squeezing your glutes.
- Return to the top position, reset, ensure you're continuing to maintain good form, and repeat.
“The squat can be performed unweighted, with a dumbbell held at the chest, or with a barbell held on the back, the front of the delts, or overhead,” says Sabar.
- Start out in a plank position: Place your hands on the floor with fingertips pointed forward and toes on the floor. Place feet about hip-width apart. Then get tight!
- Twist your hands outward (pretend you're trying to unscrew a jar lid with your left hand while tightening one with your right hand). This puts your shoulders into external rotation.
- Tighten your abdominal muscles and pull your hips slightly toward your ribs while squeezing your glutes. This flattens your back and keeps your core stable.
- Squeeze your quads as though you're trying to pull your kneecaps up your thighs.
- As you bend at the elbows to lower toward the ground, continue with the external rotation through your shoulders. The rotation through the shoulders should put your upper arms close to 45 degrees out from your body.
- Stay tight through your core and shoulders as you lower your chest almost to the floor. Your shoulders should be lower than your elbows as you press back up to the start position. Be sure to keep your neck neutral, or in line with your spine, throughout the push up. Your chest — not your chin — should reach the floor.
Are you working toward performing full "military" push-ups on the floor? Sabar suggests incline push-ups or ‘negatives.’ “Lower yourself slowly and with a perfect plank. Then get back to the start position by peeling off of the floor or coming to your knees.” You can also put your hands on an elevated surface.