Anyone who knows me knows that I am always talking up the health benefits of exercising and of being fit. What does it mean to be fit? I identify three components of fitness: aerobic efficiency (this is the “base” of your fitness pyramid, and you should typically spend the bulk of your time working on this), peak aerobic capacity (so-called VO2 max, which is the maximum volume of oxygen your body can use for aerobic metabolism or cellular respiration while working out at max capacity—higher VO2 max is directly linked to improved cardiovascular fitness) and strength/stability. I’d like to consider the importance of strength training as it relates to brain health.
Skeletal muscle strength and cognition are two seemingly unrelated aspects of human health that have some intriguing connections. New research has shown that there is a relationship between skeletal muscle strength and cognitive function, particularly as we age. Could lifting weights really help delay or even prevent the development of Alzheimer’s disease?
A recent review by Oudbier et al evaluates this link between low skeletal muscle mass (sarcopenia) and dementia. Sarcopenia is very common as we age—upwards of 15-20% of older adults have low muscle mass and unfortunately, many of them have obesity in the presence of sarcopenia. Oudbier and colleagues evaluate over one hundred publications and assess the associations between various measures of muscle strength and physical performance and brain health.
One mechanism by which skeletal muscle influences brain health, as well as over-all health, is its function as an endocrine organ. Skeletal muscle is more than just the tissue needed to move your joints. Contracting muscle also releases a wide variety of peptides and proteins, which are collectively known as “myokines” and act as signaling molecules to other parts of the body.
Certain myokines, such as cathepsin B, can cross the blood-brain barrier and exert direct effects on nerve pathways. Other myokines are known to have anti-inflammatory effects both systemically and in the brain, as well as positively impact energy production.
For example, muscle-generated brain-derived neurotrophic factor (BDNF) promotes expression of genes involved in nerve cell mitochondrial biogenesis (the production of new mitochondria). Mitochondria are the ATP (energy) production organelles inside our cells and a healthy number of mitochondria is critical in avoiding excessive oxidative stress or dysfunctional energy metabolism.
Additionally, the downstream effects of most if not all myokines include triggering the release of more myokines, creating a positive feedback loop and amplifying their effects. On the other hand, physical inactivity is thought to directly inhibit myokine release.
Training your muscles can also impact other body systems that in turn improve brain health. Resistance training increases the production of hormones like testosterone and growth hormone. These hormones play roles not only in muscle growth and repair but also in cognitive function. Testosterone, for instance, has been linked to improved spatial and verbal memory.
No matter how old you are, it’s never too late to start strength training. “I wish I had less muscle,” said no seventy-year-old ever. If you’re not doing anything right now, start at two thirty-minute sessions of strength training per week. And strength training doesn't need to be complicated--all you need is two dumbbells to start! If you have more time to devote to it, increase your time every six weeks gradually working up to two or three hours per week. However, if your schedule allows you only one hour per week, that’s still fantastic—you get significant benefit from that!
Wondering how to start? Come see me for a meet ‘n greet—make your appointment at www.renewalhealth.us .
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