Many people are unfamiliar with isokinetic exercise, but it can be a valuable training tool in your fitness routine or training program, particularly if you are recovering from an injury.
Isokinetic exercise is a method of resistance training that utilizes specialized machines that operate at a constant speed throughout the full range of motion no matter what effort level you exert.
In this guide, we will differentiate between isometric, isotonic, and isokinetic exercises, discuss the uses and benefits of each, and give you examples of isokinetic exercises to try out on your next trip to the gym or physical therapy appointment.
Isokinetic exercise is a type of resistance exercise that uses specialized isokinetic machines that operate at a constant speed throughout the range of movement no matter what effort level you exert.
With isokinetic exercises, the “iso-“ prefix refers to “same,” and the suffix “-kinetic” refers to motion. Thus, the isokinetic machine will keep its speed and motion the same throughout the movement, no matter how much force you exert.
Isokinetic exercises can target and improve muscular strength and endurance, depending on the muscle groups you are targeting, the force you are exerting (the functional resistance), the speed settings you are using on the isokinetic exercise machine, and the duration/sets you do.
There are three primary types of muscle contractions in fitness training: isometric, isotonic, and isokinetic.
Isometric exercises require your muscles to contract without generating movement in your body.
Essentially, an isometric exercise is a static hold. You are still doing muscular work, but no joint movement is occurring.
Examples of isometric exercises include forearm planks, high planks, wall sits, and holding the lower position of a push-up with your chest hovering just over the ground.
Although most people are unfamiliar with the technical term “isotonic, “most strength training exercises you typically perform are considered isotonic.
Isotonic exercises are those in which the resistance remains constant, so the amount of tension in the muscle remains the same while the muscle shortens (referred to as a concentric muscle contraction) and lengthens (eccentric contraction) throughout the range of motion.
Pretty much all the standard resistance training exercises you do in your exercise program—such as repetitions of curls, squats, deadlifts, and triceps extensions—are isotonic.
As mentioned, with isokinetic exercises, the speed of the movement stays the same, no matter how much force is exerted.
Although isokinetic exercises can certainly sound complicated and require the use of specialized equipment, there are several benefits, including the following:
The primary setting in which isokinetic exercise is performed is in physical or occupational therapy to rehab and recover from musculoskeletal injuries, surgeries, or functional musculoskeletal impairments after strokes or other medical conditions.
For example, one study 1 Gioftsidou, A., Ispirlidis, I., Pafis, G., Malliou, P., Bikos, C., & Godolias, G. (2008). Isokinetic strength training program for muscular imbalances in professional soccer players. Sport Sciences for Health, 2(3), 101–105. https://doi.org/10.1007/s11332-008-0047-5 found that isokinetic exercises were effective at increasing the strength in the knee flexors and extensors (quads and hamstrings) and correcting muscle imbalances in professional soccer players.
Isokinetic exercises are particularly beneficial in rehabilitation settings after musculoskeletal injuries because this type of exercise essentially has a built-in injury-risk-reduction safety net.
No matter how much force the user exerts on the isokinetic exercise machine, the machine will not move at a faster speed, which can reduce the risk of any kind of muscle tears or ligament or tendon strains.
The physical therapist or occupational therapist overseeing the treatment can set specific limits for speed and resistance on the machine that the user cannot accidentally override, allowing for very controlled, low-risk, and safe movement.
Studies have shown 2 Maurer, B. T., Stern, A. G., Kinossian, B., Cook, K. D., & Schumacher, H. Ralph. (1999). Osteoarthritis of the knee: Isokinetic quadriceps exercise versus an educational intervention. Archives of Physical Medicine and Rehabilitation, 80(10), 1293–1299. https://doi.org/10.1016/s0003-9993(99)90032-1 that isokinetic exercises can reduce the pain associated with osteoarthritis of the knees.
Isokinetic exercises are uncommon outside physical therapy, occupational therapy, or other rehabilitation settings.
Most people who scan their local gym for isokinetic exercise examples will be disappointed because isokinetic exercise training usually involves specialized and costly exercise equipment.
A specialized isokinetic exercise machine keeps the speed of the motion constant no matter what force the user is applying throughout the range of motion by way of electronically controlled hydraulic mechanisms.
With that said, with deliberate attention to the speed at which you are moving, it’s possible to perform isokinetic exercises in your own training with certain pieces of standard exercise equipment.
Consider the following examples:
An exercise bike, such as a stationary bike or a spin bike (indoor cycle), can be used for isokinetic exercise if you pedal at a constant rate or cadence.
Throughout the pedal stroke, your muscles exert different levels of force depending on the joint angles, but the speed of your motion remains constant.
For example, studies 3 da Silva, J. C. L., Tarassova, O., Ekblom, M. M., Andersson, E., Rönquist, G., & Arndt, A. (2016). Quadriceps and hamstring muscle activity during cycling as measured with intramuscular electromyography. European Journal of Applied Physiology, 116(9), 1807–1817. https://doi.org/10.1007/s00421-016-3428-5 that have used EMG to measure muscle activation have found that the rectus femoris, the primary quad muscle that runs down the center of the thigh, is most active during the first quarter and last quarter of the cycling pedal stroke.
The quads are biarticular muscles because they help flex the hip and extend the knee.
The cycling pedal stroke begins when the foot is at the top position and ends when the foot returns to the same position.
Therefore, the first quarter involves the initial crank of the pedal towards the floor until the foot is as far forward as it will get (and is halfway to the lowest position down by the floor).
The last quarter of the cycling stroke takes your foot from the position that it gets behind you back up to the top.
During the downward phase of the pedal stroke, the quadriceps (particularly the rectus femoris muscle) contract to straighten the knee, and then at the end of the pedal stroke, the quadriceps contract to help flex the hip.
However, during the middle portion of the cycling pedal stroke, the quadriceps are not all that active because the knee is flexing passively (so no eccentric quad contraction is required), and the hip is extending.
Therefore, the amount of force that your quads exert throughout the cycling pedal stroke is not constant, but the speed at which your legs are moving and your quads are contracting is constant. This makes it an isokinetic muscle movement.
An arm ergometer is essentially an exercise bike for your arms, so the same principles can apply here to perform isokinetic exercises.
Walking on a treadmill can also be an example of an isokinetic exercise, although not quite as perfect as cycling on an exercise bike.
If you walk at a constant speed, your muscles make isokinetic contractions at the same speed throughout the range of motion.
One example of isokinetic exercise machines is dynamometers, specialized exercise equipment that can measure force output during movement at a controlled and constant speed.
These tools are often used in exercise testing, research, and rehabilitation settings to assess muscle strength and measure progress.
Theoretically, it’s possible to turn most standard strength training exercises with resistance bands into an isokinetic exercise by deliberately, manually controlling the speed and rhythm of your reps.
Although trying to do this yourself without a specialized exercise machine will likely be less precise, you can somewhat replicate the experience of an isokinetic exercise.
You would need to move at a constant speed throughout the entire range of motion for the exercise.
Because you are using resistance bands, the amount of resistance will change throughout the range of motion based on the degree of stretch in the band due to the distance from the end of the band to the point of attachment.
In most cases, working with a physical or occupational therapist is the best way to integrate this form of exercise into your workout routine.
Still, you can certainly try to implement some isokinetic training on your own using an exercise bike or controlling the speed of your strength training exercises.
Check out our guide to a total body workout using resistance bands:
