A few studies caught my attention this week, not for being all that surprising or groundbreaking or even new, but because they jibed with something I’ve been mulling over: physical activity in old age.

Studies: the first and second. I grouped these together because they largely deal with the same thing. The first, actually a review of a couple dozen separate studies, discusses how basic physical capability seems to predict mortality later in life, while the second focuses entirely on the predictive ability of a person’s walking speed. This is redundant to anyone who’s ever felt a euphoric post-workout rush or the satisfaction of completing a physically taxing task, but judging from the number of people who make endless loops in the parking lot to score that sweet spot by the door and avoid empty staircases in favor of crowded escalators, we are in the minority. Things like grip strength, the time it takes to rise from a chair, the ability to balance on one leg, and walking speed were strong determinants of mortality. The death rate was 1.67 times higher in folks with weak grips, 2 times higher in those who were slowest to rise from the chair, and 2.87 times greater in people who walked at the slowest pace. Most of the studies reviewed were of older subjects, but the physical activity markers were predictive in young people, too. The walking study found that normal gait speed was an indicator of mortality with predictive power similar to BMI, smoking status, blood pressure, and other chronic conditions.

Again, nothing new. Muscle mass and activity levels have always predicted better health and longevity (that’s better longevity, not just longer longevity) in older folks across a number of studies, and our personal anecdotes corroborate this: your grandpa, the former farmer, with the iron grip, even on his death bed, or the old lady who still lives on her own and walks past your house daily who must be pushing ninety. It’s important to note that the relationship between activity and mortality is probably circular. Stronger people are more active and walk faster, while weaker people are less active and slower because moving around is hard when you’re weak. Stronger people have more organ mass and better metabolic health. Weaker people might not survive surgery or illness. Activity reinforces itself; the stronger get stronger (because they move) while the weaker get weaker (because they cannot). It’s not a simple linear relationship with a single precipitating event.

So, how do we maintain strength, muscle mass, and activity levels up to and into old age for the largest number of people who need it most? Walking’s a no-brainer, but that’s not quite enough, and besides, walking quickly isn’t the cause of increasing longevity; it’s an indicator of strength, which is a causative factor. Are we supposed to stick our grandparents in the power cage with copies of Starting Strength and gallons of milk just to stave off early mortality?

Not according to the last study. It is an older one that found low-load (30% of 1 rep max) high-volume (to failure) leg extensions produced more muscle protein synthesis than high-load (90% of 1 rep max) low-volume (to failure) leg extensions. Now, I know this isn’t anything close to the final word. Serious athletes and lifters will still be getting stronger, faster, and bigger using big, heavy weights and lower reps, just like millions of them have done for decades. It used leg extensions, which are a bit easier to perform to failure than squats. And finally, going to failure with 90% of your 1 rep max isn’t a typical “high-load, low-volume” workout. It would have been cool if they’d used an intermediate weight in another group, maybe something like 70% of 1RM. There is a key takeaway, though: it suggests that heavy barbell lifting isn’t required to get regular people stronger, which is a position I lean toward (see Primal Blueprint Fitness). Anything works, as long as it’s hard. Intensity is key, whether you’re doing the PBF bodyweight-centric workouts or lifting really heavy things. That means older or inexperienced people can build and maintain vital strength and physical capability late in life without putting themselves at risk by engaging in complex weighted movements.

Do the studies’ results ring true for you? How active are, or were, the oldest people in your lives? Is intensity the key, rather than load?

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