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Pacing oneself is really, really hard. I think that difficulty stems from how different the psychological approach to pacing is from the rest of life. Usually, life rewards joyous enthusiasm, jumping into tasks and doing as much work as possible as efficiently as possible. Pacing, meanwhile, rewards those that are meticulous and detail-oriented and willing to have no fun at all (at first).
It’s like the dichotomy between an artist and an accountant. The artist often lets it flow. The accountant charts flow rates down to the tenth decimal point. Being an artist may be sexier, but in running, you need to pace yourself with the diligence of an accountant.
Why? Our brains and hearts are not amazing at knowing exactly how much effort we can meter out before slowing down and breaking down. Most of the time, paces that are too hard don’t even feel hard at first. And where brains and hearts don’t do the job, we need to step in with strategic methods to avoid self-sabotage.
But how do we do that when self-sabotage is so freaking fun? My dog Addie needed help answering that question. She can’t pace at dinnertime, so she needs a bowl like a maze to avoid choking on kibble.
If you’re anything like me, you may show similar puppy-like enthusiasm at start lines, sprinting off for the first few miles before realizing you made a terrible mistake.
So what can runners that get too excited for race-day kibble do? Here are some factors to consider when developing your pacing strategy.
In longer races, exceeding aerobic threshold can reduce efficiency
Aerobic threshold is the effort range when the body switches from primarily burning fat for fuel to primarily burning glycogen (essentially carbohydrates). Every runner has nearly limitless fat stores due to how fat is converted to energy in cells. While glycogen lets an athlete put out more power, stores are limited and cannot be fully replenished during intense exercise.
In addition, above aerobic threshold, waste products associated with fatigue begin to increase in concentration in the bloodstream and muscles. Athletes can clear those chemical byproducts while exercising without substantially dialing back effort (unlike when they exceed lactate threshold), but most may eventually have to reduce power output as glycogen stores decrease, as outlined in this 2013 article from the Journal of Physiology.
If your race is 3-5 hours or below, you don’t need to worry too much about exceeding aerobic threshold since you’ll probably be able to replace glycogen and not accumulate too many waste products (assuming good training, with the caveat that everyone is different). However, when you go longer than that, aerobic threshold often acts like a speed limit. You can exceed it, but eventually that risk may result in getting pulled off the road altogether.
The big complication is that aerobic threshold feels pretty easy. Most athletes can still talk readily above aerobic threshold without too many issues.
Takeaway: in short races, don’t worry much about aerobic threshold as long as you are refueling as you go. In longer races, start easier than you think you need to. Going more slowly at first allows the body to initiate fat burning when perceived exertion may differ from actual exertion. For long ultras, 10 minutes in the first 10 miles is often worth 100 minutes (or more) in the last 10.
Approaching or exceeding lactate threshold can decrease power output the remainder of the race
Lactate threshold is the effort range when the body produces more waste products than it can clear, resulting in rapid fatigue accumulation (it’s usually associated with an effort an athlete can hold for about an hour). Crossing (or approaching) that range for an extended period can reduce subsequent power output even if effort is decreased thereafter. A 2016 article in the Journal of Strength and Conditioning research found reductions in running economy even at moderate lactate concentrations, emphasizing “the importance of avoiding intensities above LT in the early parts of a dominantly aerobic endurance competition.”
If a race is under 60-90 minutes, you don’t have to worry so much about that. Just avoid fully red-lining and going into severe oxygen debt. But in races longer than 90 minutes (and especially those longer than 2 or 3 hours), elevated lactate concentrations can correspond to diminished running economy and accelerate energy depletion.
Lactate threshold especially comes into play on uphills. What feels like a sustainable, moderate effort can go well into the red zone without it being obvious at first. That may be fine for trained athletes in moderation, but probably shouldn’t be sustained for an entire climb outside of short races.
Takeaway: in short races, go for it like a super-charged puppy and don’t worry so much about all this gobbledygook. In long races, avoid the type of effort that takes your breath away at almost all costs unless your training and background indicate you can still finish strong afterward.
Musculoskeletal breakdown can result from minor deviations in effort from what you are trained for
Muscle strength is rarely the limiting factor in running performance. The amount of power you’re putting out is usually pretty small, especially compared to primarily anaerobic sports like weightlifting or soccer. However, muscles can still undergo breakdown from repetitive, low-level stress, especially on downhills, as outlined in this 2017 review article in the journal Sports Medicine.
When going downhill, the body absorbs higher impact forces than on flats or ups. On steep downhills, leg muscles may undergo eccentric muscle contractions, when the quadriceps lengthens under load. Picture it—on a steep grade, your foot hits the ground with your knee nearly straight and quad engaged. As you absorb the impact force, your knee bends and that engaged quad stretches. Like a taut rope being pushed to the breaking point, that can sometimes cause micro tears in muscle fibers that decrease subsequent power output (and cause the downhill-induced soreness we all know and hate over the next couple days).
Going faster than you are trained for, whether on downs or around switchbacks or when you see the race photographer, can cause minor amounts of breakdown in the connective system. Some breakdown is probably nothing to worry about. It’s the natural byproduct of racing. But too much, and you might find yourself with two useless sacks of flesh-colored Jello where your quads used to be.
Takeaway: in short and long races, try to avoid a ton of urgency in your movements unless you specifically train for those stresses. Urgency isn’t a scientific term, but a good general rule is that if it feels really fast, you’re probably going beyond what you trained for and may be undergoing more muscle damage than you should. Even if your heart rate is low on a descent, your muscles can still be breaking down, so focus on letting it flow rather than pushing hard.
Feeling like you are moving forward is more advantageous than feeling like you are moving backward
The most important part of our physiology for performance is the brain. That seems obvious when you think about it, but it’s easy sometimes to distill our running down to the legs and heart and cardiovascular system. Our brain controls all of those things, and lots of studies show that how we feel about what we are doing is sometimes as important as what we are actually doing.
Moving up through a field of competitors is an empowering emotion that can push athletes to even stronger running later on. Getting passed and falling back is the opposite; it can be like deflating a full balloon in the best cases, or popping the balloon altogether in the worst.
Takeaway: Prioritize the second half of your races in all events over a mile or two. At most races, the margins at the start are minimal compared to those at the end. And finishing strong can be more fun and less painful than the alternative.
The best races involve the strongest finishes
All of the databanks of race results support the idea that strong second halves lead to strong races. The best marathons are almost always with even or negative splits, that is, finishing the 2nd half as fast or faster than the first. The same goes for most track races over 800 meters.
In trail and ultra races, where exact paces are less relevant, the most important factor is simply finishing strong. The best athletes are usually not those who run their fastest mile right before the finish (unlike road and track running), they are those that can run downhills with purposeful flow late in races and move efficiently on uphills even when they are hiking.
Takeaway: the big idea of the pacing discussion is not to worry about any of the specifics too much. We don’t want to go full accountant, because trail races are not run with spreadsheets. Instead, we want to internalize some of those accountant principles. Think of the full event, invest in your fitness intelligently and set yourself up for success longterm. Err on the side of an easier start. Hike when you need to on uphills, let the over-eager puppies run away from you on downhills.
The race really starts at halfway. Have the courage to start patiently, and you may find the strength to finish faster than ever.
—David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. His book, “Happy Runner,” is co-written with his wife Megan and available for pre-order now at Amazon.