Muscle contractions happen when our brain tells the body one of two things: to move a muscle, or keep it stationary in a specific position. Two main types of contractions are isometric and isotonic contractions. Both of these contractions can help you build muscle over time, but isometric and isotonic movements involve quite dissimilar routines. So what are the main differences of isometric vs isotonic exercise? Here is a very simple explanation.
Isotonic Exercise Definition
Isotonic exercise is movement where you are working your muscles through a range of motion. Isotonic exercise is in fact the most widespread type of strength training. Examples of isotonic exercises are, weightlifting, calisthenics, cycling swimming, rock climbing, and most sports: These are all isotonic movements. Isotonic muscle contractions involve a change in your muscle’s length and as well as an increase in muscle tension. Muscle contractions that are isotonic involve either a muscle lengthening or shortening that is accompanied with an increase in muscle tension. An example of isotonic exercise is a biceps curl. A biceps muscle shortens to lift the dumbbell and there is tension on the muscle to be able to support the resistance.
Isometric Exercise Definition
The simplest way to explain what isometric exercises are that they are static, exercises, and don’t involve movement. When you do an isometric exercise, you do not move your muscles through any kind of range of motion. What you do is hold a pose which involves a muscle contraction as long as you can. Isometric exercise examples would be a plank, or exerting force against an immovable object like a wall. An isometric contraction does not change the length of your muscle. Our previous example of an isotonic exercise, which is the biceps curl is isotonic while you are lifting the dumbbell, but becomes isometric at the top of the movement when you squeeze or hold the muscle contraction. Older people will remember Charles Atlas and his “dynamic tension” principle where he demonstrated the benefits of isometric exercise for body building. He illustrated this with his proverbial skinny guy on the beach who gets sand kicked in his face by a beach bully. The skinny guy gets his revenge after he does Atlas’ “dynamic tension,” routine. Returning as a buff hunk, he scares away the beach bully. See more on Charles Atlas’ “Dynamic Tension” here.
Examples of Isotonic Exercise
According to healthyliving.azcentral.com, most sporting activities are considered isotonic. Here is the explanation offered by their website.
“Most sports can be characterized as forms of isotonic exercise. Cycling, swimming, basketball and racket sports all put your joints through various ranges of motion using gentle to moderate stress. Likewise, activities of daily living, such as walking, climbing stairs and gardening, involve isotonic movements including stretching, reaching or bending. This type of movement is less prevalent in modern life, since time and effort-saving machines have replaced many manual labor tasks. Isotonic exercise has a cumulative effect, so it’s possible to fulfill your daily exercise needs with small bursts of activity sprinkled throughout the day, according to Harvard Health Publications.”
Offered also from the same website is a specific example and explanation of an isotonic exercise via the leg extension. This is a particularly explicit because the example sites arthritis as a limiting condition against using other exercises. The leg extension can be seen as an alternative isotonic movement for leg development if one is constrained from all weight bearing leg exercise.
“If knee arthritis limits your ability to participate in sports or other isotonic activities, try a leg extension. The Arthritis Foundation recommends this safe and effective isotonic exercise for the quadriceps. This exercise strengthens the muscles around your knee without causing impact to the knee joint. Perform this exercise in a seated position in a straight-backed chair. Starting with your hips and knees bent to 90 degrees and your feet hip-width apart, raise one foot slightly above the floor and slowly straighten your leg. Hold your leg in the straightened position for six to 10 seconds. Slowly bend your knee and return to the starting position. Repeat on the opposite side.”
Examples of Isometric Exercise
Isometric exercises can be particularly helpful, especially in the field of rehabilitative medicine for sports injuries. This is because muscles are able to contract, but do not have t move thru a range of motion. Examples of these conditions are lifted from healthyliving.azcentral.com.
“You can strengthen and rehabilitate an injured shoulder without putting the joint through excessive movement using isometric exercises. Ohio State University’s Wexner Medical Center recommends a series of isometric exercises that you can do using just your body or with a wall. To strengthen the front of your shoulder, make a fist with one hand and place it in the palm of the other hand. Holding your arms in front of your chest, press your fist into your palm while resisting with your palm. Hold for a few seconds then relax and repeat. For the back of your shoulder, stand with your back towards a wall. Place a pillow between the wall and your elbow. Press your arm backwards into the wall. Hold for a few seconds then relax and repeat.”
Isometrics can also be very useful in situations where you have to be inconspicuous of doing exercises such as in the office. Here is a knee and hip workout example again from healthyliving.azcentral.com.
Knee and Hip
“To strengthen you knee with isometrics, sit on the floor or a table with your leg stretched in front of you. Squeeze your thigh to fully straighten your leg while flexing your ankle and lifting your toes up. Hold the contraction for five seconds, then rest for three seconds. Repeat up to 50 times. Perform an isometric exercise for the hips in a seated position with a pillow, towel or small ball between your knees. Squeeze your knees together and hold for 10 seconds.”
Isotonic and isometric exercises both have their advantages. One should not see these two forms as opposing or competing types of movements, but rather as complementary exorcises that we have to incorporate into our routines. They are exercise principles that develop strength, flexibility and build muscle when we know how to use them in conjunction with each other.