Even for those of us who love endurance above all else, there’s something about sprinting. Your top speed can win or lose races, and can also serve as an indirect marker of muscle and tendon properties that affect how efficiently you run even at lower speeds. It determines whether you catch that bus, return that passing shot, and, eventually, get out of that armchair. Many of the challenges of daily living, once you hit your 70s and 80s and beyond, are essentially tests of all-out power rather than sustained endurance (though both are important).
The problem is that sprint speed starts declining after your 20s, and most endurance athletes have no clue how to preserve it. A recent paper in the Journal of Aging and Physical Activity, from former British Olympic sprinter Craig Pickering and John Kiely, both of the University of Central Lancashire, and Dylan Hicks of Flinders University in Australia, asks two linked questions: Why, exactly, do sprinters get slower as they age? And how can we use this knowledge to slow the decline?
The why question is, on the surface at least, fairly straightforward. Older sprinters take shorter steps and their feet spend longer in contact with the ground, presumably because they’re less able to generate explosive force with each step. That’s consistent with the finding that older sprinters have less muscle, and in particular less fast-twitch muscle, than younger sprinters.
But it’s not just a question of how much muscle you’ve got. In fact, some studies suggest that you lose strength more rapidly than you lose muscle, which means that the quality of your remaining muscle is reduced. There are a bunch of different reasons for muscle quality to decline, including the properties of the muscle fibers themselves, but the most interesting culprit is the neuromuscular system: the signals from brain to muscle get garbled.
One notable example is in the organization of “motor units,” which are groups of muscle fibers controlled by a single neuron. With age, some motor units get disconnected, which is bad because the orphaned muscle fibers become useless. The good news is that, if you remain physically active, neurons from other motor units will sprout new connections to add the orphaned muscle fibers to their existing bundle. Over time, you end up with fewer motor units overall, with each motor unit containing a larger number of muscle fibers.
It’s great that you’re able to save these muscle fibers—but the consequence of using fewer neurons to control the same amount of muscle, as the authors point out, is that “motor control becomes more coarse-grained, movement smoothness diminishes, motor precision and efficiency decline, and energy costs and injury risks increase.” That’s about as good a description as I’ve ever read of how it feels trying to do sprint workouts in your 40s.
So how do we combat these changes? Pickering and his co-authors have several suggestions.
Train Your Muscles
Getting stronger, or at least avoiding getting weaker, is the big one. The authors cover their bases by recommending that your resistance training routine should include workouts that aim to build muscle size (e.g. three sets of ten reps at 70 percent of one-rep max); workouts that aim to build strength (e.g. two to four sets of four to six reps at 85 percent of max); and workouts to build power (e.g. three sets of three to ten reps at 35 to 60 percent of max). My take on that, for those of us from the endurance side of the spectrum, is that whichever style of workout you choose is likely to have benefits as long as you do it consistently.
Figuring out how to improve muscle quality and neuromuscular control is murkier terrain. The authors suggest training to improve coordination through exercises that challenge balance, stability, and reflexes, such as single-leg balance drills. One advantage of this type of training: it’s not as draining as typical “reps to failure” strength workouts, so it may provide more bang for your buck if you can’t handle as many intense workouts as you used to.
On that note, the standard advice that veteran athletes give you when you hit your 40s is that you can no longer recover as quickly. Strangely, the authors point out, the relatively sparse data on this question doesn’t find any differences in physiological markers of post-workout recovery between younger and older athletes. The main difference is that older athletes feel less recovered—and in this case, it’s probably worth assuming that those feelings represent some kind of reality, even if we don’t know how to measure it. More resistance training isn’t necessarily better.
For me, the biggest barrier to working on my sprint speed is the fear of injury. The authors suggest three key strategies to mitigate injury risk. One is “regular exposure to high-speed running,” which is entirely logical but not super helpful to those who have already fallen off the wagon. Advice: reintroduce sprinting gently and gradually, perhaps with post-run strides once a week. The second is eccentric loading exercise for the hamstring, such as the dreaded Nordic hamstring curl. And the third is calf strengthening exercises such as heel drops.
The final ingredient is to make sure you’re adequately fueled. Both resistance training and protein ingestion stimulate a surge of muscle-building, but older adults display “anabolic resistance,” meaning they get less of a surge for a given stimulus. The solution, as least for protein, is to give a bigger stimulus. A typical recommendation for athletes in their 40s and beyond is to aim for about 0.4 grams of protein per kilogram of bodyweight with each meal and after workouts. That works out to 25 to 30 grams of protein for a 150-pound adult: a tuna sandwich with a glass of milk and a handful of nuts, for example.
There are some other suggestions in there, like creatine and beta-alanine. Creatine, in particular, is almost unique among legal muscle-building supplements in that there’s solid evidence that it actually works. But for most endurance athletes, I suspect there’s a lot of low-hanging fruit to pick before you start worrying about supplements. If you want to keep that top gear running smoothly, lift some weights, do some balance exercises—and, you know, sprint.
Hat tip to Chris Yates for additional research. For more Sweat Science, join me on Twitter and Facebook, sign up for the email newsletter, and check out my book Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance.