Tag: aging

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Exercise only preserves the muscles you actually use

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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It was great to see the big response to the MRI pics I posted a couple of days ago showing the well-preserved leg muscles of a 70-year-old triathlete. Very striking stuff. But let me now offer the following caveat:

This is a figure from a new study from the University of Western Ontario, just posted at Medicine & Science in Sports & Exercise. They analyzed the biceps brachii (arm muscles) of nine young runners (average age 27), nine old non-runners (70), and nine lifelong masters runners (67). They measured the number of functional motor units (i.e. group of muscle fibres activated by a single motor neuron), which typically declines with age. As you can see, the two old groups were pretty much the same, far below the young group.

In contrast, the same researchers studied leg muscles (tibialis anterior) in a similar group of volunteers last year (as I blogged about here) — in that case, the older runners did preserve the number of motor units. What this tells us is that exercise, on its own, doesn’t preserve all the muscles in your body: in the words of the researchers, there’s no “whole body neuroprotective effect,” or at least none that shows up in this relatively small study. It just preserves the muscles you’re using on a regular basis. So that’s still good news for triathletes, but maybe not as good for runners and cyclists!

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The incredible unaging triathlete

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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Here’s a pretty graphic illustration, from a recent paper by Dr. Vonda Wright and her colleagues (hat tip to Laura McIntyre for the forward), of the importance of lifelong physical activity:

It’s from a new study freely available at The Physician and Sportsmedicine that took detailed measurements of 40 masters athletes between the ages of 40 and 81, and found a surprising lack of age-related muscle loss:

This study contradicts the common observation that muscle mass and strength decline as a function of aging alone. Instead, these declines may signal the effect of chronic disuse rather than muscle aging.

 

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Exercise -> serotonin -> antidepressant

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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It’s well-established that exercise can be a powerful tool against depression (as Gretchen Reynolds wrote about in the New York Times a few months ago). What’s less clear is how and why it might help. A new study in  Medicine & Science in Sports & Exercise, from researchers at the University of Sherbrooke, offers some evidence for the theory that exercise can boost serotonin levels in the brain. This, of course, is pretty much the same as what the most common antidepressants (SSRIs: selective serotonin reuptake inhibitors) do.

The study was pretty straightforward. They had 19 men with an average age of 64 perform a 60-minute bout of exercise at moderate intensity (average HR 129 beats per minute, 68% VO2max). Then they measured several proxies of serotonin production, since it’s very difficult to directly measure neurotransmitters in the brain. The result: levels of tryptophan — the key precursor which is converted into serotonin — roughly doubled.

Is this a surprise? There was previous evidence in studies of rodents and younger humans that exercise boosted tryptophan availability, but it wasn’t clear whether the same effect would occur in older adults. This is particularly important because we become increasingly susceptible to depression as we age, suggesting that some of the mechanisms that help us ward off depression stop working quite as well.

Of course, one of the problems with “prescribing” exercise as a depression treatment (as Reynolds notes) is that once you’re depressed, it can be extremely difficult to summon the motivation needed to maintain a regular exercise program. Still, this study suggests that exercise might help to prevent depression in the first place, particularly as you get older.

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Aging: does the average decline as much as the extremes?

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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My Jockology column in today’s Globe and Mail takes another look at aging and physical decline:

It’s the chicken-and-egg question of aging: Do we become less active as we get older because our bodies start to break down, or do our bodies start to break down because we allow ourselves to become less active?

For years, it was widely accepted that humans would start getting slower, weaker and more fragile starting in their 30s. But new studies on topics ranging from the cellular mechanisms of aging to the time-defying performances of masters athletes are forcing researchers to question this orthodoxy. It seems increasingly likely that the first signs of decline are more a function of lifestyle than DNA: If you keep using it, you’ll be well into middle age before you start losing it. [READ THE WHOLE ARTICLE…]

One of the studies discussed in the article is this analysis of the finishing times of 900,000 German marathoners and half-marathoners, published last year. The researchers argue that the rate of decline of mid-packers is a better way of judging “natural” aging processes compared to the outliers who set age-group world records. For fun, I plotted the average finishing times of the runners in the German study, and superimposed the curve that you’d get if they declined at the same rate as age-group records. It’s pretty clear that this group of midpackers does decline at a slower rate:

 

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Knee bends make you smarter?

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

***

The best way to improve your cognitive function is to… strengthen your quadriceps muscles?! That (sort of) is the message of a new study in the European Journal of Applied Physiology by researchers in Japan.

In brief: they measured cognitive function in a group of 39 older men (average age 69) using the “Mini-Mental State Exam” (MMSE), and compared to results to measures of elbow, knee and ankle strength. They found that knee extensor strength (i.e. quadriceps) was significantly correlated with MMSE scores, but elbow and ankle strength weren’t. To some extent, this isn’t surprising: cognitive decline is often linked to declining ability to carry out everyday tasks, though it’s not entirely clear which is the cause and which is the effect. (Does physical weakness condemn you to sit helplessly in your chair, causing your mental faculties to atrophy? Or is it mental decline that stops you from doing your usual activities, causing your muscles to weaken?)

But this doesn’t explain why knee strength predicted cognitive function while elbow and ankle strength didn’t. One possibility is that the knee is more significant because it’s a larger muscle mass, so it’s more capable of affecting the levels of hormones like insulin-like growth factor 1 circulating in your body, which in turn affect brain health. This is pretty speculative. A simpler possibility is that knee strength is more important to mobility (e.g. getting in and out of chairs) than ankles or elbows. (And a third possibility is that the result is simply a fluke due to small sample size.)

Anyway, this raises the question: can you get smarter by doing deep knee bends? The study tried this, putting 27 of the subjects through a three-month, six-day-a-week home training program involving simple things like sitting in a chair then standing up. The results were a little unclear because the changes were very small after such a light training program — but the increases in MMSE score were indeed correlated (with p<0.05) with increases in knee extensor strength. In other words, those who achieved the biggest gains in knee strength also saw the biggest gains in MMSE score.

So what does this mean? I don’t think it’s anything earth-shatteringly new. To keep your wits about you, you have to stay active; to stay active, you need to have the physical ability to get around. Most previous studies on exercise and cognition have focused on aerobic exercise, which produces very strong effects on the brain. The message here is that you can’t neglect your muscles — particularly the big ones that get you out of your chair and walk you down the street.