Injuries are the bane of the runner’s life. More than any other impediment, they thwart the efforts of runners to build fitness and achieve competitive goals. For this reason, injury risk management is a critical component of the training process. If there is a way to reduce injury risk, you want to know about and, if possible, implement it.

A new study in the International Journal of Sports Medicine sheds new light on how manipulating your training workload over time can help you avoid injury. A team of Dutch and German researchers enlisted 23 recreational runners to keep detailed training diaries for two years. An analysis of the data collected revealed that increases in the acute:chronic workload ratio predicted injury, where acute training load (ATL) was calculated as the average of running duration multiplied by intensity over a period of one week and chronic training load (CTL) was calculated as the average of running duration multiplied by intensity over a period of four weeks. What this study found, essentially, was that when a runner’s acute training load exceeded their chronic training load by 10 percent or more, the likelihood of an injury occurring within the next two to three weeks spiked.

The phrase “keep the ball rolling” is a summation of a training philosophy shared by a lot of today’s top running coaches that relates to the study I just described. I reflects the belief that the training process should aim toward slow, steady progress and avoid sudden leaps. Of course, a runner must first get the ball rolling in order to keep it rolling, and there’s inherent risk in this critical phase. But once you’re past it, the goal is to reduce the risk associated with workload increases as close to zero as possible without allowing progress to stall out altogether. This approach works best if you generally keep your chronic training load close to the highest sustainable level, which is to say the highest level you could keep up more or less indefinitely without burning out.

This study helped me better understand something I’ve noticed about my own running, which is that I don’t get injured as much as I used to. I’ve come to think this is largely because I keep the ball rolling. In the past, I kept repeating a cycle of getting injured, taking time off and losing fitness, getting healthy again and resuming training, going after big race goals, and getting injured again. I seldom took foolish risks in ramping up my training, but I reckon my ATL was more than 10 percent greater than my CTL more often than I realized. In any case, over time I learned what my body could and couldn’t handle, what it likes and doesn’t like, and today my personal training formula consists almost exclusively of what my body likes and can handle.

Keeping the ball rolling, for me, entails doing 14 hours per week of training in 12-12 sessions as a baseline. I repeat this routine week after week, with the majority of sessions (a lot of one-hour easy runs, uphill treadmills walks, indoor and outdoor bike rides, and elliptical rides; 30 minutes of strength training every third day) never changing. What do change are the key workouts: the higher-intensity runs and long runs. These become gradually more challenging and more race-specific as I get closer to my next targeted “peak.” The training load does increase, but very gradually, which keeps me healthier than I used to be and is okay from a fitness perspective because it’s pretty high even at baseline (except when I get COVID-19 and am out for an entire month).

Although I rely mainly on experience and tacit knowledge to keep the ball rolling in my training, there are some rigorous, quantitative online tools that runners of all experience levels can use to manage their injury risk by properly managing their training load. One is TrainingPeaks’s performance management chart, which tracks acute training load (“fatigue”) and chronic training load (“fitness”) continuously as you upload your training data. Another, which we’ve told you about in previous newsletters, is PWR Lab, an app that app analyzes smartwatch data to monitor injury risk and help runners make smart training decisions to stay healthy. PWR Lab is offering a coupon code that members of the 80/20 Endurance community.

Every runner should have a collection of mantras to use as appropriate in both training and racing. Add “Keep the ball rolling” to your collection.

One hundred years ago, Scandinavian athletes dominated elite distance running. They trained rather differently from today’s elite runners. Hannes Kolehmainen is a good example. His primary fitness activity during the long Finnish winters was cross-country skiing, and even in the summer he did more walking than running. He was, however, among the first elite runners to adopt the then-innovative method of interval training, and that’s a big reason he was arguably the best runner in the world in the late 1910’s.

Fast-forward to 50 years ago. By then, the Lydiard revolution had occurred, and most of the top runners around the world were running 100-plus miles per week, mostly at low intensity. If this formula sounds eerily similar to how today’s top runners train, that’s because it is. Although some innovations have occurred within the past half-century (among them vastly improved strength-training techniques and depletion workouts), the pace of evolution in best practices in endurance training has slowed markedly since Kolehmainen’s day.

This was only to be expected. The human body is the human body. It’s not changing (much), and for this reason endurance training methods can’t just keep getting better and better ad infinitum. But this doesn’t mean they can’t get a little better than they are today. So, what might be different in 2068-9?

Let me begin to answer this question by stating what won’t be different. A high-volume, mostly low-intensity approach will still rule, because it simply cannot be improved upon. The only real alternatives—training less and doing everything fast—have been tried and they don’t work as well.

When making any kind of prediction about the future, the tendency is to assume that science and technology will be the main drivers of change. This could well be the case with respect to endurance training. For example, imagine a technology that dramatically accelerates recovery from training stress and thereby increases overall training tolerance (so that athletes can train even more). Earlier this year I tested a product that is supposed to do exactly this by sending energy impulses into the body. Does it work? Probably not. But it’s entirely possible that something along these lines that doeswork will come along.

As a coach, I’m especially hopeful that advances in science and technology will enable both coaches and athletes make better decisions about how to individualize, plan, and adjust training. Some experts anticipate improved genetic testing to revolutionize training program individualization, but I’m not among them. Genes  tell us surprisingly little about what works best for an individual athlete. A much better picture is provided by starting an athlete off with a program that is based on what works best for athletes generally and then customizing and adjusting it based on ongoing measurements of how the athlete is doing. Already it’s possible to do this quite effectively by simply paying attention to performance in key workouts and how the athlete is feeling. But there’s certainly room for improvement.

For example, through proteomics, coaches and athletes might be able to determine when an athlete is heading for a setback and take measures to avoid it. More immediately, products like PWR Lab are using a similar approach (ongoing collection of vast amounts of relevant data) to predict when injuries are likely occur so that these can be minimized.

On the other hand, it’s entirely possible that the most impactful innovation in endurance training methods will be low-tech, albeit informed by science. These types of advances tend to come out of left field. In 1968, nobody imagined that intentionally depriving the body of carbohydrates before and during select workouts would be a best practice. Who’s to say that sleep-deprivation training (doing select workouts after skipping a night of sleep) won’t be a thing in 1968, having been found to upregulate certain genes related to mental fatigue resistance? Or perhaps endurance athletes will sometimes perform heavy deadlifts in place of active or passive recoveries between high-intensity intervals. And don’t rule out the possibility that elite runners will do some or all of their runs wearing weight vests of gradually decreasing weight over the course of a training cycle.

Unlikely, I know. If I had to wager on the endurance training innovation that is most likely to gain traction at the elite level within the next 50 years, I would put my money on some form of brain training. Specific contenders including zapping the brain with electromagnetic energy before hard workouts, performing mental exercises during certain workouts, and doing similar exercises at rest, between workouts.

May we all live long enough to find out!

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