By David and Megan Roche
You can run really far. You can run really hard. But you can’t run really far and really hard without bonking.
When it comes to energy, there is one main point that most runners doing long-distance races can focus on: aerobic threshold (AeT). AeT is the intensity range at which the body switches from primarily relying on fat oxidation for fuel to primarily relying on carbohydrates. Above AeT, breathing rate increases and fatigue sets in more quickly. Below AeT, the body has enough oxygen to perform without substantial fatigue build-up. Perhaps more importantly, improving your AeT will save your glycogen stores from depletion, pushing back the dreaded bonk (hopefully past the finish line altogether). And it’ll probably even make you faster at shorter distance races where bonking isn’t a concern.
It’s helpful to think of it in terms of running economy. Rather than improving the raw variable AeT, we want to improve velocity at AeT, or how fast your body can go (or how much power it can put out) before switching to increased glycogen utilization. The main way to do that is to run lots, mostly easy. High-volume aerobic training spurs angiogenesis, increasing the numbers of capillaries you have to power exercise. Plus, there are tons of beneficial adaptations for muscle fiber composition, biomechanical durability, and just about every neuromuscular and metabolic variable you can think of.
But it’s not just easy running. To improve vAeT, you should also raise the running economy tide more generally. As they say, a rising tide raises all boats. Similarly, improving lactate threshold and VO2 max will improve AeT if done in a strategic way. For athletes we coach, our favorite workouts involve shorter-duration intervals with more than enough recovery. Why? Shouldn’t it be super hard? No, helpful-question-asker. We have found that for most runners to improve running economy, particularly vAeT, it’s all about intervals that feel smooth and sustainable, which ensures the athlete isn’t running more slowly than they could at a given effort. Here are 4 intro workouts (each done with a warm-up and cool-down of 15 to 20 minutes easy running):
15 x 1 minute fast/1 minute easy: the fast portions are long enough to find a groove around 5k effort, but not so long that form breaks down. You can speed up the easy recoveries to “float” effort (marathon or 50k for most people) to get an added aerobic stimulus
5/4/3/2/1 minute fast with 2-3 minutes easy recovery between: on the fast portions, think 10k to start, and 5k to finish, with the last minute faster still. The progression lets you find the effort without straining
20 minutes moderate/hard, 5 minutes easy, 8 x 30 seconds fast/2 minutes easy: think 1-hour effort on the tempo, then mile effort on the strides. Speed begets strength, and this workout combines both
4 x 2 minute hills hard (run down recovery), 20-30 minute moderate tempo run: on the hills, let your body push, ending each one gassed, then run the tempo around marathon effort with a faster finish. As you get fit, running faster on tired (but not exhausted) legs will improve your ability to clear waste products during efforts
And just about any other workout will work too! Just make sure that the goal of your efforts is not to go hard, but to run smooth. When smooth becomes fast, your AeT will start to be optimized, and your performance at almost every race distance should improve. Add smart fueling, you can make bonks a thing of the past.