Longevity Briefs: Resistance Training May Improve Nerve Function

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Everyone knows that as we age, our muscles grow weaker. Some may assume that this is entirely due to changes in the muscle tissue itself. However, changes in the peripheral nervous system (that is to say, the parts of the nervous system that lie outside of the brain and spinal cord) carry a large share of the blame. With age, nerve conduction speeds decrease and neuromuscular junctions (where motor neurons connect to muscle fibres) degrade, resulting in muscles losing some of their nerve supply. This contributes to slower reaction time and decreased muscle strength respectively, both of which put people at greater risk of falls and fractures in old age.

We know that resistance training can be an effective way to maintain muscle mass and strength even in old age, but can resistance training help maintain the peripheral nervous system? There’s some evidence that resistance training boosts nerve recovery after injury, but what about in healthy, non-injured adults? This study was designed to answer that question.

The discovery:

Researchers recruited 48 participants, ranging from 18 to 84 years old. Participants were classified as ‘young’ (18-35) or ‘old’ (aged 60 and above). They were then divided into four groups: a young training group (14 participants), a young control group (12 participants), an older training group (14 participants), and an older control group (8 participants). The training in question was a 4-week handgrip resistance training program, conducted three times per week, using a grip training kit. Before and after this period, the researchers measured the median motor neuron conduction velocity (NCV) and maximal handgrip strength in both limbs of all participants.

The results: both the young and older training groups showed significant increases in NCV compared to the control groups who did not train. But how did age affect the extent of the improvements? Somewhat surprisingly, the older adults demonstrated adaptations to the training that were just as strong as those seen in the young adults, suggesting that that older adults do not necessarily have less nerve plasticity in response to training. The young training group also saw a significant increase in handgrip strength, but older training group did not – this was most likely due to the relatively short 4-week duration of the intervention.

The implications:

These findings suggest that resistance training, even a short-term intervention like 4 weeks of handgrip exercises, can enhance nerve conduction velocity and potentially counteract age-related nerve deterioration. It suggests that incorporating even low-intensity resistance training into your routine could be beneficial for maintaining nerve health throughout life and into old age. Resistance training programs have already been shown to reduce frailty and mortality in old age, but it’s good to have confirmation that this is partly through beneficial effects on the peripheral nervous system. Further research into the mechanisms at play might also help us develop other treatments that mimic resistance training to restore nerve health.