Maintaining Muscle Strength with Cross-Education
Broken bone? Stuck in a sling or boot post-operatively with nothing to do? How can you fill those 6 weeks other than binge watching Love is Blind?
When you are immobilized or lose the use of a limb such as with stroke patients, your muscles will shrink and you will lose strength. The whole “use it or lose it” saying is actually true. It happens surprisingly fast. At the 6th hour of immobilization, your rate of protein synthesis starts to decrease. Not only are you not building protein, but your body also breaks down whatever proteins you do have into smaller pieces. Is there anything you can do to manage the decline?
There isn’t a whole lot you can do for hypertrophy, or muscle building. That requires you to stress the actual muscle that you want to bulk up. However, you can limit your strength loss through a little bit of magic called cross-education. This phenomenon is described as the increase in strength and function of an untrained limb when you workout the opposite limb. Let’s say you break your right ankle, and you are in a boot and can’t workout your calf. You can stimulate strength adaptations on the right side by working out the left calf.
Mind. Blown.
How does that work? Because of the lack of hypertrophy, we know the strength improvements are not due to the growth of the muscle fiber. Instead, it is thought that the strength gains made using cross-education are due to neural adaptations. Working out one side stimulates your neuromuscular system, which is how the brain and nerves communicate with a muscle to get it to contract. That messaging gets passed on to the other side, and increases the excitability of those pathways, even if you are not directly training it. This means that when you get the cast removed, you have maintained some connectivity to those muscles, and are starting from a better place than if you did nothing.
Are there certain types of exercises that can harness the power of cross-education better than others? Yes! Here is what you would want to look for:
Eccentric Exercises: Many studies have shown greater cross-education benefits with eccentric-focused strength exercises, which is achieved when a muscle resists lengthening. As an example, let us look at a calf raise. The action of going up on the toes is the concentric, or shortening phase of the movement, where you calf muscle is being engaged and shortening. The action of lowering the heel is eccentric. To emphasize the eccentric phase, you could take 3 seconds to lower your heel to the ground, thus using your calf muscle to resist lengthening.
High Load: This doesn’t mean to failure, but looking at about 6-8 repetitions for 3-4 sets at a high effort with lots of rest.
Using a metronome: Some studies have shown that using an external stimulus can also heighten the strength gains. This is because you are challenging that neuromuscular system by getting the muscle contraction to sync up with something outside of your body.
Unsure of how to implement this strategy with your specific injury? Send me an email or book an appointment, virtual or in-person, and we can start putting you to work!
