Researchers from the Cleveland Clinic evaluated 18 stroke patients who developed partial paralysis of one lower limb. The researchers wanted to see if progressively more difficult cycling could improve the function of the affected leg. They did this by having the patients ride a unique bike that could measure how hard their legs were working. Biking rather than a walking eliminated any balance issues that might affect how much work the legs could perform.
A study about cycling
The key to this study was to encourage strength and endurance training after stroke by cycling hard. While you might not care how fast you can ride a bike fast, normal walking is important. And high effort cycling is one of the best ways to improve walking ability.
As you know, after a stroke, the ability to walk is dependent on step length and the difference between the affected leg compared to the unaffected leg which results in a crooked gait and foot placement problems. Stroke patients often sway, stumble or cannot walk in a straight line. The specialized bike called an ergometer can measure speed, force, rotation, and other parameters necessary to correct an abnormal or inefficient motion.
More effort leads to better coordination
In the early days of stroke rehabilitation, the beliefs were that increased resistance could lead to more spasticity and decreased muscle function. But this and previous studies have overruled this notion. In fact, increasing resistance during rehab increases muscle strength, coordination, and reduces jerky movements. Smoothness also improved in this study which was an unexpected result.
We all know that muscles depend on nerves to function. When the nerves are damaged due to stroke, they send mixed signals to the muscles. This results in things like spasticity, weakness, and poor control. The more signals the nerve receives from limb movement due to increased workload, the more it can send messages to improve the muscle’s movement, coordination, and speed. This study attempted to determine if more intense workloads helped the damaged limb to perform more like the non-affected leg. It also looked at whether the motions were symmetric and smooth. It turns out that cycling helps the legs work better together after experiencing a stroke.
More resistance increases nerve communication
During this study, patients started cycling with 20 Watts, and every two minutes increased the workload by 20 Watts. After 100 Watts, they increased the load by 40 Watts every two minutes. Heart rate was measured during the exercise to ensure the patients were safe and not overexerted.
It turned out that at the highest possible resistance level, the affected leg produced as much force as the unaffected leg at medium resistance levels. The difference in the amount of power generated got less with increasing resistance, probably due to improved communication between nerve cells of the left and right side of the body with less dependence on the brain. The term ‘muscle memory’ comes to mind which is the idea that repetitive training of muscles can result in an automatic ability to repeat the task such as bike riding. No one forgets how to ride a bike because the muscles remember (thanks to the nerves) that motion automatically. Cycling hard on a stationary bike after a stroke appears to benefit leg coordination and strength. Both are essential for taking a stroll.
The lead author of this study is Susan M. Linder, Cleveland Clinic, Cleveland, Ohio.