We at Stride Strong Physical Therapy strive to make our patients stronger. Usually deficits and impairments lie with patients having weak or damaged muscles that need to be strengthened for return to walking and running. Your physical therapist will draw upon his/her knowledge of your weaknesses and use a combination of functional and isolated exercises to progress you. But what exactly is the evidence of efficacy between these different types of physical therapy exercises?
A functional exercise is usually one that involves multi-planar (different planes of movement) and multi-joint movements. An example of one is the "lunge and twist" exercise that involves use of multiple muscles and joints to control. It is a very effective exercise in mimicking real-life scenarios and activities. So using our example, the lunge and twist can actually be likened to activities like bending over to tie your shoelace, picking an object from the floor, or even running up a hill.
An isolated exercise is like the picture above, where the participant pushes against a resistance with a focused force on only one muscle group against one joint. There is usually no daily activity that likens itself to this type of exercise (unless if it's violently kicking the person in a chair in front of you, using our example!). These exercises have to be done with care and guided with precision because the amount of force enacted on that one joint is heightened and more focal. Note, for example, that the participant in the photo is extending her leg to less than 50 degrees - if she lifts much higher than that, joint pain on her kneecap is likely to ensue because of higher joint forces on a relatively smaller joint surface.
So which method of exercise is more effective?
There has been a rising trend in the last few years for fitness professionals and physical therapists to push for more functional exercises so patients can gain neuromuscular dynamic stability and practice elements of their sport more. Isolated machine-type of exercises, on the other hand, have gone out of vogue thanks to Cross-fit and Tough-Mudder challenges.
However, scientific evidence points to the need to incorporate both forms of exercise into an exercise rehab regimen. (See sources below) I am going to pick one such scientific article to prove this point.
In a randomized control trial, Jackson et al. measured the effects of isolated versus multiple joint exercise on knee musculature in normal, healthy subjects. Her team put one group of subjects through functional exercises (double leg jump. single leg hop, smith machine squat, etc) and compared strength AND function gains with another group who did only isolated exercises (calf raise machine, hip extension machine, etc).
Her results? Both groups showed significant improvements of both strength and functional measures. There was no statistical difference for strength and functional gains between the groups.
If they're not any different, can I just do one type?
Understand that functional and isolated exercises are not any different when it comes to strength gains and functional tests (like vertical jump and forward reach tests) - but where they differ is in the practice of movement. There is much to functional exercise that benefits motor control and motor learning. Not only do muscles have to be trained strong, but the brain also has to be trained to fire the appropriate muscles to allow the body to move with speed and stability.
Conversely, it is also important to gain individual muscle strength before progressing to complex movement exercises. Otherwise, a weak muscle group could cause a weak link in the movement chain and compensatory muscle activation takes place, raising the potential for body damage.
Therefore, we choose to do both functional and isolated exercises in our patients. If you ever have a question about the purpose or plan for the exercises your physical therapist prescribes to you, just ask and they'd all be happy to explain why!
So there's the science behind it in a nutshell, and below are the sources for the science:
- Kruse, LM et al. Rehabilitation after ACL-Reconstruction: A systematic review. The Journal of Bone & Joint Surgery. 94-A: 1737-1748, 2012.
- April Jackson et al. The Effects of Isolated Versus Multiple Joint Exercises on Knee Musculature - Normal Subjects. ISAKOS Poster Presentation. Toronto Canada. May, 2013.
- Anderson, A, et al. Prospective, Randomized Clinical Trial of the Effects of Open, Closed and Combined Kinetic Chain Exercises on Subjects with Patellofemoral Pain Syndrome. Poster Presentation. Las Vegas NV. Feb 2014.
- Halbart, G et al. A Comparison of Isolated Total Leg strengthening vs. Functional Training on strength, balance, and agility in health individuals. Poster Presentation. 2015.