First published on www.mp-body.com
How many times have you heard someone older than you say things like: “Don’t get old” or “Wait to you get to be my age”?
We can’t stop aging but we don’t have to feel like we are getting older – in our bodies, health and energy levels. New research shows, intense resistance exercise is a key part of that.
It’s all in the Efferent Drive
Efferent neurons send impulses from the central nervous system to your limbs and organs. A neuron is a specialized cell that transmits nerve impulses; basically a nerve cell. Essentially, our Efferent Drive is our ability to excite those impulses from our central nervous system to our organs and limbs (i.e. contacting muscle).
Remodeling of the nervous system occurs from age-related loss of muscle strength (1). The gradual loss of motoneurons (nerve cells that spread impulse to a muscle), contribute to the deleterious effects with age, resulting in reduced motoneuron firing frequency (2), and a slower rate at which impulses are spread from one nerve cell to another (3).
Basically, this is the science behind what occurs when our efferent drive slows down.
These impairments compromise the efferent drive to the muscle. Basically, this means that our ability to forcefully contract our skeletal muscle and do manual work decreases! Our skeletal muscles are what causes us to do movement (e.g. pick up a box, walk upstairs). Skeletal muscle is also what gets developed from resistance exercise and gives us that lean look when combined with quality nutrition. The loss of our ability to move our muscles is not a good thing!
Anti-aging strength training
Strength training in the elderly has shown to improve motoneuron recruitment and firing frequency. Efferent drive, specifically motoneuron firing frequency, and likely also motoneuron recruitment, can be improved by strength training in the elderly.
In Metabolic Precision, we call this high-intensity strength training FIRE, which stands for Focused-Intense Resistance Training!
Interestingly, even the strongest elderly individuals, with similar muscle strength as young individuals, exhibited substantial deficits in efferent drive. There may be some deficiency that occurs over a lifetime when one does not participate in strength training. It seems that a short-term strength training program can’t overcome this deficit.
The question is: does a lack of strength training over many decades lead to irrefutable neuronal loss, which might not be restored once it is lost?
Let’s look at a study that compared master athletes who were involved in long-term high intensity strength training with recreationally active and sedentary elderly individuals (5).
What does the research tell us?
The main finding was that the strength-trained master athletes had two-fold higher maximal voluntary contractions compared with the sedentary and recreationally active age-matched individuals.
This indicates that high-intensity strength training in particular may be necessary to preserve efferent neural drive and that physical activity per se is not sufficient to maintain efferent drive. This is somewhat surprising but may suggest that high-intensity strength training is essential to preserve the neuromuscular function with age.
It may be that high-intensity strength training, targeting the fast twitch motor units (i.e. a neuron and the muscle fibers it controls), could be particularly beneficial for counteracting the age-related loss of our nerves ability to communicate to our muscles. The results from this study are in accordance with this assumption.
Take home message
This research has presented us with a very important nugget of knowledge! We now know that efferent drive to contracting muscle is compromised with aging. Furthermore, elderly subjects involved in long-term strength training prevent this decrease in efferent drive.
In contrast, no difference in efferent drive was observed between recreationally active and sedentary old subjects. This indicates that high-intensity strength training is beneficial for counteracting the age-related loss of efferent drive.