fat adaptation

3 Hottest Topics for Ultrarunners: Strength Training, Downhill Repeats, and Fat Adaptation

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By Jason Koop,
Head Coach of CTS Ultrarunning

Earlier this week, I was invited to a compare-and-contrast interview with another ultrarunning coach that eventually would become the subject of an article. Over the years, I have come to enjoy these types of discussions and debates with coaches both inside and outside of CTS. Particularly when the discussion is with other CTS Coaches, I’ve been known to be quite, um, how shall I say… passionate, about certain viewpoints. Such passion has resulted in a few F-bombs, several eye rolls, at least one instance of a fist pounding on the table, but all in all they’re generally a good time.

While there are many aspects of coaching athletes that are black and white, there are just as many that are various shades of grey. Because of this, I’ve come to realize many debates will end up in the agree-to-disagree category. In any case, I always learn something even if I don’t agree with the solution provided by another viewpoint. Sadly, the discussion slated for this week never materialized and I was left with a sense of emptiness from what could have been.

Having been in many of these discussions over nearly 20 years, there are a handful of topics that go around and around and around, seemingly with no end in sight. They are the topics coaches just have to agree to disagree about. In the coming weeks, I will expand on each of the topics below. As a primer (AKA a tease so you keep reading for the next month), here’s an overview of the three most controversial topics I see in ultramarathon training.

Should ultrarunners strength train?

Strength training and the associated effects on running have been some of the most studied areas within endurance training. You would be hard pressed to find a coach or athlete who has not done some sort of strength training routine at some point, nor a book that doesn’t cover it in some way. However, despite copious amount of research, and articles and coaches advocating for strength training, ultrarunners hit the gym inconsistently at best.

The case for strength training

Strength training advocates generally fall into two categories:

1) strength train to improve Running Economy (the amount of oxygen used per minute at a given speed)

2) strength training to prevent injuries.

Both rationales are well documented in the literature, across a wide spectrum of athletes and scenarios. In many coaches’ viewpoints, strength training is a no brainer. There is lot of bang for buck with a simple 30-minute routine performed 2-3 times per week.

The case against strength training

The detractors of strength training argue that strength training takes time, effort and energy, and that time is better spent elsewhere. If you want to strength train to improve running economy, then the strength training has to be difficult enough to impose a stress. Think of lifting heavy weights or doing explosive plyometric work. You are tired and maybe even sore afterwards, and that impacts your run training somewhere down the line. If you are doing strength training to mitigate your injury risk, just rest.

My take on strength training for ultrarunners

If you want to strength train simply because it makes you feel good, go for it. If you want to strength train to specifically improve your ultrarunning performance, don’t do it. While I understand the mechanisms of how strength training is used to improve performance and mitigate injury, I feel a runner’s time is better spent elsewhere.

Should ultrarunners do hard downhill repeats?

All ultrarunners know the lead legs sensation caused by the muscle damage induced by thousands of feet of descending. You can have a solid stomach, a great attitude, and lung capacity that would fill a stadium with air, but when your quads are shot, you ain’t moving very fast. To combat this fatigue, ultrarunners have routinely turned to running hard downhill repeats in training.

The case for running hard downhill repeats

If something is a failure point on race day, do whatever you can in training to fix it. Such is the case for training your quads for the downhill. Advocates for hard downhill running will take the approach that ‘seasoning the quads’ is an essential component of ultramarathon training, particularly when the event you are training for has many thousands of feet of descending. Run hard downhill in training and that running overloads the musculature to create an adaptation that better equips you to handle the downhills in your race.

The case against hard downhill repeats

Downhill repeats are a high risk, low reward training mode. On the high-risk side of the equation, impact forces during downhill running are larger, which can increase injury risk. Additionally, there is an acute risk of injury from a fall or twisted ankle. Finally, on the low reward side of the equation, eccentric loading (active lengthening of the muscle fiber) does not take much stress to impose an adaptation. So much so that the term ‘inoculation effect’ is commonly used to describe how one single bout of eccentric exercise has protective effects against future bouts.

My take on hard downhill repeats for ultrarunners

Hard downhill repeats are unnecessary, extremely risky, and provide little additional benefit compared to simply running downhill at a normal speed during training. Whenever I have used downhill running specifically to induce some sort of adaptation, it has been in small doses, with an elite athlete and for a specific purpose. If you run downhill at a normal training speed and can get vertical gain and loss close to the gain and loss per mile for your race, then you are likely to get all the adaptation you need. If you live in an area where you do not have access to as much vertical gain/loss as you feel you need, your time is still better spent focusing on your cardiovascular fitness as opposed to seasoning your quads.

Should Ultrarunners become fat adapted?

No one likes to bonk. Sports science had developed numerous gels, bars, drinks, and now ketone esters in an effort to combat the dreaded bonk. In addition to the supplements, athletes have attempted to manipulate the ratio of fat and carbohydrate they burn during exercise in order to spare muscle glycogen. To achieve these fat adapted outcomes, athletes can manipulate their daily macronutrient intake (eating a low carbohydrate, high fat diet), train in a fasted state and/or train with reduced carbohydrate availability.

The case for becoming fat adapted

Athletes have a limited amount of carbohydrate that is stored in their bodies and (nearly) limitless amount of energy that they can liberate from fatty tissue. If you shift your fuel utilization to favor fat (vs carbohydrate), you can stave off the bonk as well as reduce your need for exogenous carbohydrate.

The case against becoming fat adapted 

It takes more oxygen to liberate energy from fat as opposed to carbohydrate. That extra oxygen needed to utilize fat as a fuel negatively impacts running economy, essentially forcing a runner to work harder (intake more oxygen) for the work rate required. This limits the intensity and the amount of work that can be done at higher intensities, and therefore puts a governor on the improvement an athlete can make. Additionally, dietary manipulations are notoriously hard to implement and adhere to.

My take on fat adaptation for ultrarunners

Intentionally manipulating dietary macronutrient intake or carbohydrate availability during training in order to achieve a higher rate of fat oxidation is not useful for ultrarunners. By virtue of a high aerobic training volume, ultramarathon athletes are already excellent at utilizing fat for energy. Chasing additional adaptations in this area is problematic, can increase the chance of injury (through calorie restriction), and limits the improvement a runner can achieve (through reduced running economy and therefore reduced work load).

And there you have it! My take on the three most passion-inducing aspects of ultramarathon training. If you simply want the answers, feel free to tune out for the next few weeks. If you want to learn a bit more, and maybe get a little riled up in the process, stay tuned!


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Comments 11

  1. Pingback: Is Strength Training Worthwhile for Ultramarathon Runners? - Jason Koop

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  3. Thanks for the summary format with the pro, con, and your experienced opinion. That could have been three long podcasts… I owe you, like, 6 hours.

  4. Re: Fat adapted. I have a couple of good friends who got substantially faster (improved their times significantly on longer races) immediately after switching to Keto or at least something between Keto and Paleo. They swear by it. One thing they claim is that carbs become “rocket fuel” during a race, because your body isn’t used to them normally. I’m tempted to try it, don’t thing it could hurt. But I sure like my carbs…

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  6. As with any debate whether an athlete should or should not do this or that, the answer is always “Well, it depends”.
    As the coaches, we should focus on training by using training principles (principle of: readiness, individual response to exercise, specificity, consistency, adaptation; to name the few) rather than debating methods of training. Methods are many, and that is for reason because not one method will work on two different athletes, working towards different goal.
    Thanks for the article!

  7. Thanks Jason,
    Not what I was expecting to read! r.e. the strength training and fat adaptation. I have found the opposite for adding a moderate amount of strength work specifically for ultra trail with significant elevation gain. I am currently building up for UTMB and am doing more than I have done previously to see if that also helps. I am feeling my way to find a balance total work load vs fatigue by doing the muscular endurance sessions on my easier weeks.
    I agree r.e. the downhill repeats.
    Fat adaptation: I would suggest building the big aerobic base is exactly this. The challenge i had was if I didn’t eat and did hit the wall it was ugly. So I put myself through a 12 week fat adaptation block with fasted long weekend trail runs – 3 hrs plus. Repeating this eased the bonk, I still will slow down and can feel it but don’t hit the wall and can continue at a slower pace. This has been really useful when I haven’t ingested enough in a few races… I know I can continue (as long as I stay hydrated!!)

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