The Case For Shorter Long Runs (Sometimes)

Published December 14, 2021 10:58AM

I am going to start this article with a controversial statement. Hot dogs are sandwiches. Actually, that’s not controversial, because it’s a stone-cold fact. The USDA defines a sandwich as “a meat or poultry filling between two slices of bread, a bun, or a biscuit.” That’s self-evident! Case closed! …Hmm … I’m now realizing that my law degree may have been a poor use of $200,000.

The actual controversial statement is this: I think that one of the most overrated training elements is the long run, particularly outside of specific training for longer races. By deemphasizing long run length, especially in the offseason, athletes can focus on running economy improvements through consistent aerobic development (as the chronic training stress) and speed/power (as the acute training stress). Layer those adaptations together, and specific long runs can become easier and more effective later on, even without doing them all year.

However, that rule is not set in stone, and different things work for every athlete/training approach. Let’s break down the rationale.

Aerobic System Rationale

Aerobically and metabolically, most general fitness adaptations come from chronic training stress, like consistency and weekly miles. Angiogenesis (increased capillarization around working muscles) is not substantially altered when training volume is achieved in a longer effort rather than spread out over time. Fat oxidation is stressed on every run, and particularly as glycogen stores are reduced, which likely happens well before 2 hours. It’s even possible that the stress hormone cortisol from excessive long runs (particularly those that involve glycogen depletion) could impair hemoglobin and hormone levels in some athletes, reversing aerobic benefits.

The jury is out on the overall balance of how overdistance long runs may impact protein expression, epigenetics, enzyme activity, and similar small-scale processes impacting the aerobic system, and that may vary heavily on an athlete’s genetics and background. For example, mitochondria biogenesis could be improved by long, low intensity runs under the first ventilatory threshold (think conversational effort) that require cells to generate energy over several hours. Or the mitochondria effect could go the other way from excess stress.

Based on what I have seen in coaching, I imagine there are certain cohorts of athletes that may benefit from year-round longer runs, particularly those that are faster-twitch at baseline or are planning to move up in race distance for the first time. Even when I’m trying to be controversial, I can’t help but disclaimer myself in the face so hard that I become the president of Lawyer Fight Club. The first rule of Lawyer Fight Club is that there must be 10,000 rules in Lawyer Fight Club.

Biomechanical and Neuromuscular Rationales

For the biomechanical and neuromuscular systems, prioritizing the long days could lead to inefficiency. As athletes fatigue, ground-contact time can increase and form can deteriorate, so even if an athlete maintains output, they may be doing it in a way that is less likely to translate to fast running when it counts. And the neuromuscular system thrives when stress is balanced—a good proxy is the overall principle of embracing feeling good. In practice, the endocrine system seems to ride in a sidecar next to the nervous system, and pushing too hard risks sending them both careening into the ditch.

It takes an anomalous nervous system to adapt to consistent fatigue like what many athletes describe when they get a high proportion of training volume from long runs. Many of those anomalous nervous systems are attached to athletes that become champions, so it can skew our notions of balanced training if you only look at the fastest tail of the bell curve.

On the flip side, there are likely some nervous system adaptations that act over long time horizons and are difficult to measure, like those related to fatigue resistance. Periodic longer runs may help those amorphous adaptations in some athletes, particularly those that haven’t often raced marathon and above, as long as they balance endocrine system impacts. I disclaimer so hard mothertruckers wanna fine me.

Musculoskeletal Rationale

The big benefits of extended long runs are tied to specific adaptations to the musculoskeletal system. Certain types of breakdown processes, like those from sustained eccentric muscle contractions that can happen on downhills or as an athlete fatigues, require some specific training stimulus for most athletes. Longer runs might not increase output directly, but they may increase the ability to withstand mechanical forces that prevent aerobic ability and muscular strength from translating into speed later in runs.

That potential benefit is counterbalanced by injury risk. Every overdistance long run pushes the body in a way that is abnormal, and every step into that zone risks breakdown to bet on potential adaptation. I think that the adaptation benefits rarely justify the potential costs, even if the actual risk is relatively low. Maybe a 25-mile run comes with a 5% risk of a setback for an experienced athlete. Play those odds enough, and it will end with an injury. The problem is that 19 out of 20 times, it will feel like a great decision, but it’s key to zoom out and remember that it’s just as risky all 20 times.

And even short of injury, the emphasis on muscular fatigue may not stimulate better muscular performance, just increased ability to withstand breakdown. My goal for athletes is always to try to improve running economy, making outputs take less energy. Withstanding fatigue is not a variable that alters running economy, unless we’re measuring it later in events. But introducing fatigue could diminish the ability for an athlete to achieve efficient output on the run or other times during the week.

Summary

To simplify the argument to the basics: longer long runs are risky for health and higher-output performance, and the specific adaptations needed for longer races do not require going too long too often. Around 12 weeks prior to a race that is marathon distance or farther, an athlete needs to start thinking about specific adaptations, particularly those related to the accumulation of impact and eccentric muscle contractions. Even then, I have coached athletes that only go above 20 miles 5 times (and rarely longer than 50k) before winning big 100 milers. And in other contexts, the Hansons team is famous for coaching world-class marathoners who rarely touch 20 miles in training. Super long runs are unlikely to make a positive difference for running economy, and could actually push the adaptations in the wrong direction.

Put it all together, and there is an immense amount of physiological wisdom in the old Frank Shorter principle: “A long run is 2 hours or 20 miles, whichever comes first.” He’s an Olympic champion, so the exact guidelines are less relevant for most athletes. But an adaptation of that quote that I have learned to apply in coaching is something like: “A long run outside of the 3-month period before races marathon and above is capped at 2 to 2.5 hours or 12 to 16 miles or ~25% of weekly volume, with exceptions of periodic 20 milers for very advanced athletes doing more than 60 miles per week.”