Sarcopenia, or muscle loss and weakness, is among the crueler consequences of aging. Not only are you gradually robbed of your ability to perform everyday tasks, your walking speed slows down and your fall risk goes up. That’s why staying active as you age is so important. It’s also why finding ways to slow or combat sarcopenia has been such an active area of research. Now a new study published in the Journal of Clinical Investigation could offer hope for reversing muscle weakness, by focusing on the junction between the muscles and the nerves.
Normally when a nerve sends a signal to a muscle, the muscle cell responds by opening sodium channels. The resulting flood of positively charged sodium ions causes the muscle to contract. What the researchers discovered is that we lose these sodium channels as we age, which contributes to muscle weakness.
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“We identified an important point of failure at the final step in communication between nerves and muscles,” study author W. David Arnold of the University of Missouri-Columbia explained in a statement. “And what is perhaps even more exciting is that we showed this failure is potentially reversible.”
That’s because there’s another ion channel in muscle cells: the chloride channel ClC-1. Like the sodium channel, this membrane-bound protein allows ions to pass through, in this case negatively charged chloride ions. Normally, these help repolarize the cell after contraction to get it ready for another go round. Chemically blocking these channels, the thinking goes, could offset the loss of sodium channels, restoring electrochemical balance and muscle strength.
In fact, Arnold is already collaborating with the Danish drug company NMD Pharma to test this theory in rodents. “By partially inhibiting ClC-1, we were able to make aging muscles more responsive to nerve signals and improve muscle strength in an animal model,” Arnold said. “That gives us a potential path toward eventually testing this approach in older adults.”
So some day, we may be able to pharmaceutically reverse muscle weakness. Until then, we have to keep hitting the gym. 
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