When you're working out, time certainly stands still when you're … standing still.
Think about it: How slow do the seconds tick by when you're holding a wall sit, plank, or hollow body hold? Being frozen in place doesn't make the exercise any less grueling — and suddenly, that 30-second movement feels like 30 minutes.
Those static holds are known as isometric exercises, and involve working up a sweat without moving your joints. Isotonic exercises, on the other hand, involve moving your muscles and joints throughout the exercise.
So what's better — isometric vs. isotonic? As you're about to find out, both isometric and isotonic movements have their advantages, and both should hold a place in your workouts. More importantly, by combining isometric and isotonic exercises, you can build a grueling, at-home workout program — without adding more weight to the bar.
Isometric vs. Isotonic: What's the Difference?
The key difference between isometric and isotonic exercises is that one involves movement (the latter), while one includes a static hold (the former). Below, we dive deeper into the differences between isometric vs. isotonic movements, and the advantages of each.
What Does Isometric Exercise Mean?
Isometric comes from the Greek words isos (equal) and metria (measuring). It means that while the muscle length and joint angle do not change, a muscle contraction can still take place.
When you think about exercise, you probably visualize jogging down the street, curling a dumbbell into a bicep curl, or pulling yourself over the bar into a pullup. All three of these exercises have something in common: movement. But while it sounds counterintuitive, you can still get a great workout without actually moving.
Nearly any exercise can be transformed into an isometric exercise — as long as you’re frozen in place. Several examples of isometric exercises include:
- Forearm planks
- Wall sits
- 90 degree bicep hold
- Hollow body hold
- Glute bridge (holding at the top)
- Pushup hold (holding at the bottom)
- Static lunge
You Don't Lengthen Your Muscles
Most exercises involve moving a limb or your entire body, which causes your muscles to contract and lengthen. This happens in two steps: a concentric contraction (where your muscles shorten), and an eccentric contraction (where your muscles lengthen).
The best example of a concentric and eccentric exercise is the bicep curl. When you curl a weight toward your shoulder, your biceps shorten (the concentric contraction), and when you return the weight to your sides, your muscles lengthen (the eccentric contraction).
However, you can still have a muscle contraction without movement — which is where isometric exercises come in. For example, if you were to hold the dumbbell at your hip at a 90 degree angle in a bicep hold, your muscle is neither shortening or lengthening. This static hold is an example of an isometric movement.
You Don't Move Your Joints
To have a concentric or eccentric muscle contraction, you must move your joints. For example, think back to the bicep curl example — whether you are curling the weight to your shoulder or returning it to your side, your elbow joint assists the movement. The same could be said for deadlifts or squats, where your hip joints aid in the exercise.
However, in an isometric contraction, your joints don't budge. If you are performing a 90 degree bicep hold, your elbow stays in place until you release the movement.
What Does Isotonic Exercise Mean?
An isotonic exercise involves putting the same amount of weight (or resistance) on your muscles while moving through your full range of motion. In Greek, isotonic translates roughly to "same tension."
Most exercises are isotonic exercises (unless you’re holding a static pose). Examples of isotonic exercises include:
- Bench presses
- Walking lunges
- Bicep curls
- Hamstring curls
There Is No Change in Tension
In an isotonic exercise, your muscle fibers will push or pull against the same amount of weight throughout the exercise. For example, think of a bench press: Whether you're at the top of the movement (with your arms straightened, nearly racking the weight), or the bottom of the movement (with your arms bent and the bar near your chest), you are pushing against the same amount of weight.
The same can be said for bodyweight exercises (pushups and pullups) and weighted exercises (bent over rows or tricep kickbacks). No matter where you are in the movement, your muscles will always push against the same amount of weight.
There Is Change in Movement
Unlike an isometric exercise, in an isotonic exercise you will move your muscles and joints.
Because you are physically moving throughout an isotonic exercise, there is both a concentric and eccentric contraction in the exercise. In other words, the length of the muscle will both extend and contract in a single, isotonic muscle contraction.
Isometric vs. Isotonic: What Are the Benefits of Each?
Both types of muscle contractions hold a place in your regular exercise program. Below, I dive into the advantages of each.
The Benefits of Isometric Training
If you’ve ever held a wall sit for a full minute, you know just how grueling isometric training can be.
Isometric training can help build muscle strength, even though your muscles don't elongate and shorten throughout the movement. In addition, since isometric training does not change the angle of your joints, they can be effective exercises for those with arthritis or a particular joint injury (i.e., if they're recovering from a sprained ankle). In addition, if someone has asthma or is just getting back into shape, isometric exercises can help build strength in their muscular system without taxing the lungs.
The Benefits of Isotonic Training
Because isotonic exercises involve movement, they can tax your cardiovascular system while also building muscle. For this reason, these types of exercises can be an effective tool for weight loss.
In addition, since isotonic training combines muscular contractions with movement, you can use it to build power and speed. It is actually impossible to build power or speed through an isometric movement.
Isometric vs. Isotonic Training: Why You Need Both
When it comes to isometric vs. isotonic training, one is not necessarily "better" than the other. In fact, I will argue you need both in your workout routine — particularly if you are someone who performs at-home workouts.
With the onset of COVID-19, many people find themselves working out at home. If you are familiar with strength training, you may have noticed a decrease in muscle mass and strength throughout any shelter-in-place orders (unless you have a full set of dumbbells or kettlebells at home).
However, adding weight to the bar isn't the only way to make a workout more challenging. Isometric exercises can be great supplementary or accessory exercises.
Even if you are performing a bodyweight-only workout, combining isometric and isotonic exercises will completely burn out a given muscle group. Start with an isotonic movement, then move into an isometric hold to push your muscles past the point of fatigue. Here are a few examples:
- Pushups: Perform 10 pushups, then perform a 5-second pushup hold (at the bottom of a pushup) to burnout your chest and biceps.
- Hamstring curls: Perform 10 reps of hamstring curls with a pair of socks or a towel, then perform a 5-second hamstring hold (with your legs almost fully extended).
- Pulsing squats: Perform a bodyweight squat. When you reach the bottom of a squat (when your quadriceps are parallel to the ground), hold for 10 seconds. Do 10 reps.
- Bulgarian split squat: Perform 10 Bulgarian split squats on your right leg. Before switching to your left leg, hold at the bottom of the squat for 10 seconds to completely burnout your right glute.
Isometric vs. Isotonic: Use Both
Both isotonic and isometric exercises can help bring about muscle changes in strength and mass. However, one is not particularly "better" than the other.
Instead, I always encourage you to use isometric and isotonic exercises in your workouts — particularly if you work out at home.
In the Build Bullet-Proof Health program, you get weeks of workout plans that you can perform from the comfort of your living room. With nutrition and recovery tips, and a blend between strength and cardio, it's the well-rounded fitness routine you're missing.
Plus, by blending isometric and isotonic exercises, you get a sweat-inducing workout — even without weights.
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