Your Easy Days Are Too Hard And Your Hard Days Are Too Easy

  • By Aaron Hersh
  • Published Jul 19, 2013
  • Updated Jul 22, 2013 at 11:47 AM UTC
Photo: Jamie Kripke

Precisely Stressing the System

Lactate threshold is the exercise intensity where the body starts producing more lactate than it is able to remove, so it begins to accumulate. Lactate itself is not a bad thing. Lactate does not cause fatigue, but there is an association between the point that lactate levels elevate and fatigue. When we train at an intensity just below our threshold, there is a very high influx of lactate being produced by the muscles and being metabolized and used as fuel. The main objectives of high-intensity training are both to increase the production of lactate and, more critically, increase your body’s ability to clear the lactate. Training just below lactate threshold is where we see the greatest increase in one’s ability to clear and re-use the lactate.

Given this, the majority of hard training is best done just below the lactate threshold to maximize the body’s ability to clear lactate. This training adaptation increases your maximum sustainable pace and power, which moves your lactate threshold level up to a faster speed.

Some athletes make the mistake of doing their steady-effort, hard workouts at an intensity too low to maximize lactate clearance—many people call it “tempo” training. In other words, many people spend too much time in Zone 3 during hard training (see chart on page 68) instead of Zone 4. When most people think of tempo training, they think of an intensity that creates a slight increase in blood lactate. I do very little tempo-intensity training with the athletes who I work with. This is counter to many other coaches out there. I try to limit that kind of training to no more than 10 or 20 percent of training volume. On the other hand, some individuals cross over and go above their threshold, into Zone 5, during long interval workouts instead of staying just below. Once you cross over your threshold you see a significant increase the in activation of your sympathetic nervous system, which is effectively activating the “fight or flight” response and signals that you’re under stress. That’s what increases your levels of cortisol, a stress hormone, and will retard recovery from the workout, and you’ll see a pronounced increase in the fraction of carbohydrate used for energy when you cross over. A super-threshold effort (Zone 5) is far more strenuous on you than a sub-threshold effort, and a sub-threshold effort can be sustained much longer. You might be able to do workouts that are 3 x 15 minutes or 2 x 20 minutes of sub-threshold and not feel exhausted. Whereas if you did, say, 3 x 10 minutes or 4 x 8 minutes of above threshold, you’d be pretty shot. And you’d only have accumulated 30 to 32 minutes of super-threshold training versus 40 to 45 minutes of sub-threshold training, and you only need about 48 hours to get going again after the sub-threshold workout. Recovery from super-threshold intensity is going to take longer—closer to three days before you’re recovered and able to do another quality session—which reduces your overall training density. That’s why doing hard efforts at lower, sub-threshold intensities increases the total amount of quality training time an athlete can accumulate.

Even though the majority of hard training is below race intensity, it conditions the body, when rested, to sustain super-threshold intensity on race day because the body is more able to clear lactate. When you look at what the best endurance athletes have done historically, and I don’t care if you go back 50 or 100 years, you see a very high fraction of training done at slow and steady efforts, and they have always done more sub-threshold than super-threshold training.

Our next intensity level is VO2max intervals, or intervals at Zone 6, which is another specific, critical training mode that many people don’t do enough. In other words, when athletes do intense workouts, they are typically doing these workouts in Zone 5 rather than Zone 6. VO2max running pace is all-out one-mile speed. Cycling VO2max power is the highest power an athlete can sustain for five minutes. Your heart rate at the end of a four- to eight-minute VO2max effort should yield your maximum sport-specific heart rate. You can only operate at some percentage of your threshold during an endurance race, so you need to bump up your threshold to increase your sustainable race pace. VO2max work pushes up the ceiling.

A set of 10 30-second efforts with 90-second recovery done during a moderately long session is a typical  VO2max workout for an Ironman athlete, who is going to do significantly less VO2max-intensity work than a short-course athlete, and when they do those intervals they’re going to be shorter duration with longer recovery.

Apply it Yourself

The best way for an amateur athlete to apply this philosophy without great access to knowledgeable resources is actually fairly simple. Regardless of total training volume, easy aerobic training still makes up the majority of an athlete’s training time. I’ve worked with a lot of successful age-group athletes training just 12 hours per week. Even at this relatively modest total training volume, two-thirds of that training is done at a steady-state aerobic level, with one key weekly long workout in each sport. In the swimming session, mechanics, in addition to fitness, must be stressed. For long-course athletes, a nonstop swim of 30 to 60 minutes or more is also an important factor that is often overlooked. A 20- to 30-minute steady swim is adequate for short-course racers. On the bike, it’s a steady long ride and again, long is relative to the athlete’s race distance. For short-distance racers, it could be two or three hours at the tops. Long-course athletes will likely be in the four- to six-hour range with athletes racing any distance performing short five- to 10-second burst sprints every 15 to 20 minutes to get neuromuscular work in addition to the primarily aerobic base efficiency building work. Running is the same thing. The key session may be a one- to two-hour long run, again depending on race distance, incorporating short, neuromuscular, alactate sprint-type efforts every other week (see chart on page 72 for more information on alactate training). For an Ironman athlete, we often try to build up to a single session near race distance, running between 18 to 24 miles depending on running background, history, injury propensity, things like that, and cycling typically between 110 and 120 miles. I like to go a little bit over race distance on the bike to build confidence and general endurance.

The next important effort level to complete each week is a sub-threshold, or Zone 4, type of interval swimming, cycling and running. In the pool, long intervals such as 300m to 500m repeats are ideal. In cycling, it’s ten- to 20-minute long intervals for a total of 30 to 40 minutes of work. And in running, it’s typically miles or kilometer repeats for a total of 2 to 4 miles.

VO2max intervals, or intervals in Zone 6, are the final major piece to the puzzle. One such cycling workout for a short-course athlete could be three sets of very short VO2max efforts. In a two-hour ride, the athlete does 8 x 40 seconds at 140 percent lactate threshold power with 20 seconds recovery at 50 percent threshold power, then a set of 10 30-second efforts at 150 percent threshold power with 30 seconds at 60 percent lactate threshold power for recovery followed by 12 x 20 seconds at 160+ percent threshold power with 40 seconds recovery at 70 percent threshold power with five minutes spinning between each set. A 2-mile brick run immediately follows the ride with 800m at 5K pace, then a 400m jog; 400m at mile race pace, a 200m jog; and 2 x 200m at mile race pace, then a 200m jog.

The Psychology

All the physiological training that we do often ultimately enhances the psychological state, as well. The fittest body with a weak mind doesn’t go anywhere and doesn’t win races. I would rather have somebody come in 10 to 15 percent undertrained but with a 100 percent mental readiness versus someone who’s the other way: 100 percent trained, 90 percent mentally ready. Give me a brain that’s ready. I put my money on the hungry one who’s gotten better rest than the one who’s gotten more hours of training. People think whoever has trained the most is going to win. No, definitely not. No way. It doesn’t work that way. Some aspect of performance on race day is not going to be the training that you’ve done, but the confidence that you have in the training that you’ve done. When you walk to the starting line of a race and you’re confident in the training that you’ve done and you’ve seen objective improvements in your training, you know you can produce more power for this duration, you can run a faster speed at a given heart rate and you can take fewer swim strokes for the same distance. This athlete knows objectively he is better than before. He knows he can now go do this next level; he’s not hoping that he can do it. Objectively, he knows he can. That’s a far different place mentally to go into a race. When you don’t have those objective measures of your training, you go to the start line with a lot more question marks. High performance racing comes from knowledge that you’re ready—it doesn’t come from hope. Hope is not a strategy, as they say.

RELATED: High Intensity For High Performance

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Aaron Hersh

Aaron Hersh

Aaron Hersh is the Senior Tech Editor of Triathlete magazine. To submit a question, write Aaron at

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