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You may have heard the training saying: “Easy runs easy; hard runs hard.” I think there’s an important addition to a well-rounded training plan, particularly for trail runners: “Medium runs medium.”
The strict polarization between easy and hard serves a purpose. The grey area between aerobic threshold (an effort you can sustain for a few hours or more) and lactate threshold (around an hour, with variance) is a bit like a vacation to Cancun. It’s fun to visit, but stay there too long and it starts to wear out its welcome, and before long you’ll be covered in sunburn welts while Ted Cruz walks by in the saddest Hawaiian shirt. Countless running careers have been undercut in that grey area.
But that doesn’t mean the grey area is all bad.
It gets back to the old correlation versus causation conundrum. Athletes that do their easy runs with too much effort likely have an overall approach to training that is less sustainable. They chase the quick gains and more impressive Strava files from moderate running, get some of those quick gains, then assume that those gains will continue. At that point, the transition from rapid initial gains to marginal long-term gains pulls them out to the deep end. They keep doing many moderate runs, see less progress, fail to adapt their training to a more polarized approach, and eventually find themselves treading water via injury or stagnation.
That model plays out every year in college programs across the country. Faster easy running often coincides with faster racing, leading to an association that can undercut growth after the aerobic, endocrine and nervous systems rebel against the chronic stress. Or in athletes that start their running journey later in life, any run might be moderate at first, creating an understanding that all running should be moderate even as fitness grows. That’s when you’ll sometimes have success with interventions involving heart rate caps, since excessive moderate running can undermine both low-level aerobic efficiency and upper-level aerobic capacity.
The key word there is “excessive”—we don’t need to throw the moderate-running baby out with the polarized-training bathwater. In fact, I am going on the record to say I am against throwing out babies or bathwater altogether. I am brave to take that stand, thank you for saying so.
In coaching, my wife Megan and I rarely program specific “moderate” days because these grey-area runs can be counterproductive when they are inefficient, like when completed on sore legs or during periods of high life stress. That is why doing moderate running all the time can be so negative—if an athlete feels like crap and forces the pace, it becomes a hard run that can tear them down. Instead, we use the looser term “easy/moderate.”
Easy/moderate runs involve starting very easy. As the run progresses, athletes have permission to find ease of motion without urgency, while covering ground with smooth flow on flats/downhills and efficient purpose on uphills. The runs are faster if an athlete feels good, slower if they don’t. Heart rate may be below aerobic threshold on downhills and flats, and closer to lactate threshold on climbs.
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Essentially, easy/moderate runs allow training to be dictated by the body and brain, rather than obligation to numbers on a plan or compulsion to push each day to the limit. Two major physiological principles are important to apply easy/moderate runs.
Principle One: Steady running around aerobic threshold can have major benefits for endurance, or major negative effects when forced.
Coach Renato Canova works with many of the best marathoners of all time, and these types of steady effort long runs are key to his system. In his book Marathon Training: A Scientific Approach, Canova refers to steady effort runs as being around what he calls aerobic lipidic power, essentially meaning the effort is both fast and sustainable. His training system for marathoners revolves around increasing that power so that output at lactate threshold and aerobic threshold get very close together. That’s why the top marathoners don’t look like they’re breathing all that hard at 5-minute miles—they have wildly impressive output around aerobic threshold.
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Steady runs may improve lipid oxidation at higher outputs, whereas purely easy runs don’t always have the same benefit. In addition, these runs could improve the power and recruitment of Type-I slow-twitch muscle fibers, while also spurring the production of mitochondria and capillaries. And since the runs are faster, the muscular output is greater, leading to more strength.
But there are downsides too. Go too hard, and some of those aerobic benefits erode away, while endocrine and nervous system stresses go sky-high. A steady run forced on tired legs leads to injury risk, with little benefit other than mental toughness. And if you’re after mental toughness through increased discomfort, you could just stick your finger in the trash compactor.
We frame these runs as easy/moderate to emphasize that athletes should err on the side of relaxed. The goal is to run with as much pace as possible with as little effort as possible, since that is when running economy improves the most. And we don’t want to have to call a plumber to clean the trash compactor.
Principle Two: In trail running, athletes must train for the specific musculoskeletal demands of running efficiently over varied terrain
Steady runs are especially important for marathoners, who often use long runs to lock into faster paces. Meanwhile, easy/moderate runs are geared toward trail runners who are running over varied terrain, with different paces, outputs and even form depending on the trail. The trail athletes face a much wider range of musculoskeletal and biomechanical stresses, emphasizing the ATHLETE part of being a runner. Easy/moderate runs build specific adaptations to uphills and downhills, particularly during long runs that start to approximate race pace for ultra runners. We like athletes to apply five rules to add some structure to these unstructured effort days.
- Start easy for the first 10 minutes
Let the body kick into a fully aerobic gear. No pace is too slow, like all easy runs.
- Let your body dictate the effort by finding ease of motion, without urgency
After those 10 minutes, listen to your body. What is it saying? “I feel good and fresh” = time to let the effort roll. “I am a bit ragged” = take it easier. “Five, five dollar, five dollar foot loooong” = go to Subway post-run. The cue of finding ease is what I like athletes to lock into in ultra races, and easy/moderate long runs are great for practice.
- Flow on the downs and smooth on the flats
On downhills, heart rate will be lower, so it’s a good time to practice running with focused, purposeful flow. As you adapt to the musculoskeletal demands, downhills will become free speed. On flatter terrain, embody smoothness with relaxed arms and no urgency.
- Efficient purpose on the ups, with the option to progress effort on good days
Easy/moderate runs can become extra effective workouts for trail runners due to the uphill stress. If you walk most of the ups in training, try to run a bit more. If you walk some of the ups, try to run all but the steepest grades. If you rarely walk, add a bit more power into your stride. For all athletes, on days you feel good, some of the steeper ups may approach lactate threshold effort, and that’s great for fitness. Just make sure you’re not fading too hard as the run goes on, which may indicate pacing that exceeds your current fitness levels.
- Fuel well
Because easy/moderate runs are higher overall effort, they are also higher risk. Fueling is key to improve endurance and adapt to the training you are doing, while also mitigating some of that risk.
For our athletes, easy/moderate long runs on trails are a staple outside of base period. Sometimes, they will even include 20-30 minute moderately hard tempo runs after a warm-up, which is how we can spur more long-distance adaptations without doing 30 or 40 mile runs in training. Every 4-6 weeks, a mid-week trail run may be a similar approach, often in aerobic build weeks.
Easy/moderate means that you’re giving your body the love and respect to let it tell you what it’s ready for. Use these runs in the context of a well-rounded training plan with high-end speed and low-end aerobic development, and your body will probably be telling you that it’s ready for race-day breakthroughs.
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From Trail Runner