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Strength training is for everyone, including you! With the variety of strength exercises available, it can be challenging to understand which exercises will facilitate your fitness journey and which may stifle you. Do you know the difference between isometric and isotonic exercises? And how they can help you on your fitness and health journey?

Isometric and isotonic exercises aren’t in competition with each other. Both have advantages in specific situations. When used in combination, these exercises help you obtain and maintain optimum power and strength. 

woman holding plank position (an isometric exercise) in gym

What are isometric exercises? 

Isometric exercises are the name given to a type of exercise that results in muscle contractions without any notable change in the muscle length, either in terms of shortening or lengthening. Muscles are under constant strain during isometric exercises, causing them to contract. 

A more straightforward explanation of isometric exercises is to consider them static holds, where neither the muscle nor the joints move. These holds may range in duration but are typically between 30 and 90 seconds. For instance, a plank is considered an isometric exercise. You’re holding the muscles tight, but aren’t moving them like you would in a lunge or squat.  

If you want to take on the current record for the longest time held in a plank, you would need to be in a plank position for over 8 hours, 15 minutes, and 15 seconds!

The benefits of isometric exercises  

Isometric exercises have several advantages and benefits. And there are situations where the use of isometric exercise are preferable to isotonic exercises. 

  • Rehabbing injuries where the lengthening or shortening of muscles may cause more pain than good. 
  • Helps stabilize joints. 
  • The preferred exercise for people with arthritis. 
  • Help build muscle endurance.

Studies have shown isometric exercises are effective in lowering daily blood pressure. However, be aware that if you suffer from high blood pressure, isometric exercises may increase your blood pressure during the exercises. As such, you should consult your doctor if you have any concerns. 

While isometric exercises are a form of strength training, the gains are often minimal. Isotonic exercises are a better option for building strength and increasing muscle mass.

What are isotonic exercises? 

Isotonic exercises refer to lifting a weight or using resistance bands to bring about muscle contractions. The weight doesn’t have to be a dumbbell though – your own body weight can create isotonic exercises too. Squats or push ups are a good example. 

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During isotonic exercises, muscles go through a process of shortening and lengthening. Isotonic exercises place more pressure on the joints than isometric exercises. Given the muscles are put through a process of lengthening and shortening, the relevant joint is required to respond to this and bend or rotate to facilitate the muscle contractions. 

As per the process of strength training, when done effectively, isotonic exercises can be adapted as your strength and fitness improve. Adapt these exercises by increasing the weight or changing the number of repetitions and sets. 

Man doing calf/leg curls at gym on machine

The benefits of isotonic exercises 

Most resistance exercises fall under the Isotonic banner. Lifting weights and going through a system of repetitions and sets constitutes isotonic exercises. 

The benefits of isotonic exercises are multiple and include: 

  • An effective way to build muscle. 
  • Advanced stage of rehab. 
  • Improve cardiac fitness. 
  • Increase the muscle’s ability to produce power

How to turn an isometric exercise into an isotonic exercise

As already mentioned, the plank is an excellent example of an isometric exercise. To turn this into an isotonic exercise, you must bend at the elbows, lower your body to the floor, and push up again. And hey presto, the isometric plank becomes an isotonic press-up. 

Another example of an isometric exercise is holding a small hand weight with your palms toward the ceiling. With your arm extended out at 90 degrees to your body. Maintain this status pose for 30 – 90 seconds. Depending on the weight, this isn’t as easy as it may seem. To turn this into an isotonic exercise, bend at the elbow and bring your hands and forearms toward your body while keeping your upper arm and elbow extended. This results in a bicep curl. 

woman doing bicep curls in home on gym mat with small dumbbells. Bicep curls are an isotonic exercise

How the combined use of isometric and isotonic exercises complement each other

If you have had the misfortune of an injury, you have likely been prescribed a combination of isometric and isotonic exercises. 

Consider the relatively common hamstring strain. Experts recommend specific isometric exercises to improve muscle stiffness and isotonic exercises to increase force and power. This results in a whole rehab package. 

As a general rule of thumb, isometric exercises may be your preferred choice if you are looking to rehab an injury or build muscle condition. Isotonic exercises are a better option if you want to improve your overall fitness and build muscle mass. 

There’s a time and a place for both isotonic and isometric exercises 

Consider combining isometric and isotonic exercises for the ultimate strength and conditioning program. 

When you learn to discern the specific needs of your muscles, you are more likely to achieve your strength goals. Don’t be shy in seeking advice from a personal trainer or physiotherapist; these professionals have your best interests at heart. 

Words by Ali Hall