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Endurance Training

❝What is very clear is that the best athletes in endurance sport spend ~90% of the time below the first lactate turn-point.❞
~Stephen Seiler, PhD & Dean, Faculty of Health and Sport Sciences and Nutrition, Universitetet i Agder, Kristiansand, Norway

Building fitness takes work. A very important part of it is knowing how hard, how much, how often, and why. The last one—why—affects everything else. The reason for doing something changes so it’s important to continually revisit the question. It can empower you to healthy excellence or lead to disease. It can build you up or provoke injury. The first three questions above can be much easier to illuminate. Let’s take a look into the training characteristics of the most successful female cross-country skier ever during the best period of her career—a highly impressive five-year timespan.

This study, performed in 2017 by Solli, Tønnessen, & Sandbakk, reveals a polarised training model that leading sport scientists and exercise physiologists have shown is optimal for performance, health, and longevity. Full text is available here.

There are three types of training: Endurance, Strength, Speed.
There are three intensity levels: Low-intensity training (LIT), Moderate (MIT), and High (HIT).

During the five consecutive successful years, training time was distributed as:
• 90.6% endurance
• 8.0% strength
• 1.4% speed-training

Looking deeper at the endurance training, time spent at the three intensity levels consisted of:
• 92.3 ± 0.3% LIT
• 2.9 ± 0.5% MIT
• 4.8 ± 0.5% HIT

Notice the very strong emphasis on endurance training (90.6%) and that most of it (92.3%) is done at low intensity!

I can hear the counteraction already: “Yeah, but that’s a cross-country skier… My sport needs more speed.” What’s interesting about human energy production is that for any exercise lasting longer than a few minutes, most of the energy provided comes by way of the aerobic system. Mitochondria are organelles found in large numbers in most cells and are the powerhouses for the biochemical processes of respiration and energy production. Respiration uses oxygen. Building aerobic capacity requires the stimulation of mitochondrial respiration. You can do work for a few minutes in an anaerobic (non-oxygen) environment but doing so creates an oxygen debt that can be very difficult to repay. The smart move is to keep the oxygen fire burning to build aerobic capacity. (I’ll dive deeper into this in an upcoming post.)

The three intensity levels have historically been defined by lactate levels, with the upper boundary of low-intensity endurance training (LIT) being the “first lactate turn point”. This method requires that the athlete undergo regular testing to which many have neither access nor the budget. Thankfully, sport scientists have found that percentage of maximal heart rate (HRmax) and perceived exertion are highly correlated methods for intensity evaluation. It’s important to point out that HRmax is defined as the highest heart rate you’ve reached within the last 6-12 months, in each specific sport. Running HRmax is different than HRmax for swimming or biking, or skiing.

Using per cent of maximal heart rate, intensities were defined as follows:
• Low: 60–82% of HRmax
• Moderate: between LIT and HIT
• High: 87% of HRmax

Notice the huge range given for low-intensity training! The upper boundary of LIT varies based on the level of fitness and the genetics of the individual. Only the most elite and highly trained athletes have an LIT range that extends so high. Sport scientist, Alan Couzens, has found that the average value for the upper boundary of LIT, for most athletes, is 68-75% HRmax. That’s still a rather large variance for the upper edge of LIT, but when you run the numbers there’s a big difference between 78% and 82% of HRmax.

Here’s an example with my own data. In running, my HRmax is 177 beats per minute. Thus, the maximal upper edge of LIT in running, for me, would most likely be 133. In fact, this is spot-on: I know that the sound of my breathing increases dramatically above 133-135bpm while running, and as long as I’m well rested, properly fuelled, and adequately hydrated. If I were less well trained, hadn’t slept well, or was exercising in a fasted state, that number might be closer to 120-125bpm (68-71% of run-HRmax). That’s not even close to 177*0.82=145, which is deeply taxing.

What did all the time spent in LIT look like for one of the most successful endurance athletes of all time? There was a solid amount of warm-up in order to bring her diesel engine to effective operating temperature, and most training sessions for the year were longer than 90 minutes in duration.

Low-Intensity time consisted of:
• 21% warm-up
• 14% sessions <90 min
• 65% long-duration sessions >90 min

Lastly, remember that in the training distribution, strength work was 6 times the amount of high intensity!! Most of that strength training was done in what the researchers called the General Period (GP), with a bit less in the Specific Period (SP), and a maintenance amount of in the Competition Period (CP). Strength is an important aspect of maintaining form and protecting the body from injury.

The researches concluded that “Our study supports previous findings highlighting the importance of a high training volume, using a polarized training pattern with a large amount of LIT.”

IOW, the five most successful years occurred with:
1. the highest total training volume;
2. the lowest amount of HIT (and the highest amount of LIT);
3. the largest amount of strength work. 

What we don’t learn from this study is anything about the athlete’s recovery characteristics. Remember that Stress + Rest = Growth. Did the athlete change rest habits, i.e. the use of compression boots or massage, diet, or an increase in the simplest of all performance-enhancing drugs—more sleep? We don’t know. What we do know is that the best athletes in the world and the ones who have the longest, most successful careers take recovery just as seriously as training.

What does all this mean? If you can complete your sport while holding your breath then, well, knock yourself out. If, however, you want to maximise your aerobic capacity then do lots of training at low intensity and support it with strength work and a small amount of high intensity. Make all of your training high-quality by staying aligned with objectives, just vary the intensity properly.

Does your ‘why’ for training align with the training characteristics presented here? To optimise performance, health, longevity, and success (your definition) then your why must support and infuse the how hard, how much, and how often in your workouts and plans. Check-in with yourself regularly to ensure that you’re on path.