Q & A Regarding Acidosis Tolerance

The standard athlete reaction at the conclusion of an Acidosis Tolerance workout session.

The standard athlete reaction at the conclusion of an Acidosis Tolerance workout session.

The Question

“Hi Coach Marcus. You continue to influence my thinking. 

I coach high school girls XC and I have been making a big investment in sprinting this season.

I am doing max speed (flying 30’s), speed endurance (120’s at 98%), but then do you have athletes work at 400 speed? 800m?

I am often confused about what Special Endurance is. I appreciate that you are a busy person many thinks for your consideration, and if you have time, reply to my question!”

My Reply

Good morning Coach, 

You ask very good questions!

I’m happy to offer what I can to help your thinking and application.

Sprinting is like hard liquor — best taken in small dosages with a lot of time in between shots (both from rep to rep in a session and days between sprint sessions). It takes time for the brain to reorganize and recode new, high recruitment movement patterns.

In XC, your athlete population is most likely best served by the Fly 30s (only 3 - 6 total with at least 2:00 - 3:00 recovery walk between rep) once every 6 - 10 days, on days when they are very fresh (so coming off of a rest day or a couple of recovery days).

“Special Endurance” I call Acidosis Tolerance, this is the 2x(4x120m @ 400m pace w/ 80m rec.) you saw Anna doing on a twitter post a few weeks ago. This is very tough work and I think should only be employed once every 7-12 days depending on the athlete’s fitness levels (lower fitness levels means longer time between exposures). 

Acidosis Tolerance interval sessions have 2 main aims in my book:

1) To increase the athlete’s running velocity, which will allow runners to start and finish the events faster and 2) To improve the buffering capacity, so that the runners are able to keep up their velocities during the competition despite an increasing accumulation of acidosis.

Acidosis Tolerance training interval exercises increase the activity of monocarboxylate proteins transporters of lactate (MCT1 and MCT4) through the muscular membrane, which enables a faster appearance of lactate in the blood. This kind of training also works by increasing the buffering capacity in the muscles and blood as well as by increasing pain tolerance caused by the acidosis. When the buffering capacity improves, the runners are able to keep up a fast running velocity in the face of increasing acidosis/lactate production for longer, delaying a decrease in their running velocity. The resulting adaptations produce a tolerance to these exercises known as acidosis tolerance.

There are 3 ways to progress the Acidosis Tolerance (ie Special Endurance) workouts. 

I will list them in the order I typically progress them and use the 2x(4x120m @ 400m pace w/ 80m rec.) workout as an example.

  1. Progress the Intensity (Run at Faster Speeds).

  2. Progress the Density (Shorten Rest Periods).

  3. Progress the Capacity (Increase Volume).

1. The body responds most dramatic to intensity, or in this case, the running speed. So it’s best to establish the baseline speed you deem optimal for each athlete and employ the workout until all 8 reps are at that speed or better. For example, Anna’s baseline is 17.25” (which is 57.5” for 400m). Once every rep is run at 17.25” or faster only then we will consider updating another variable. 

2. The time between each rep and set reflects the density. Right now, Anna is getting up to 80” recovery between reps in each set. We want her first to hit 17.25" for each rep with up to 80” recovery. The next step is to progress the density from 80” to 65” to 50” to 35”. When she is able to take 35” or less between each rep and run 17.25” or faster on all reps only then can we think about increasing the capacity (volume).

3. We can increase capacity (volume) in 2 ways — either increase the number of reps or increase the distance of each rep. However, we must be careful not to compromise intensity (speed run) with the volume increase. For example if we upped it to 3 sets of 4 x120, but her final set was 17.9'“ or slower for each rep and she had to take 90” rec. to run those 17.9” reps we know this is too much volume for her at the moment. More work is not more better, it is just more work. What I typically do, when the athlete demonstrates readiness for increased volume, is add one rep to a set until I get to 6-8 reps in a set. So the session could progress to 5x120, 4x120, then 2 x (5x120), then 6x120, 5x120, then 2 x (6x120) and so on. Remember, capacity (volume) is the final variable to be increased! Many get impatient and seek to increase volume early and often, thinking it will lead to bigger and quicker gains, but this is misguided thinking.

The goal of training is to increase the velocity an athlete can sustain over a particular race distance. The best way to do this is by modulating the intensities which the athlete is subject to in training. So if you want your women’s XC top-7 to run 6:20/mile for 5,000m then all your high intensity work will be at 5:20/mile or faster and your long and strong (or “steady”) work perhaps around 6:40-7:00/mile pace. I ballpark easy runs at +50% of race pace, so about 9:30/mile — yes this pace seems very slow, but the goal of an easy run is to facilitate recovery, nothing more. Where a lot of people get tripped up is doing a lot of work at race pace (however, I have found there to be very little transfer to competition of from doing large amounts type of work in season — during the season athletes do get an adequate training dosage of race pace work in on race day) and running their easy/recovery runs at a moderate speed, effectively impeding full recovery.

I’ve found athletes can workout 3 times a week, or every other day (with a glycogen replenishment day, i.e. rest day) weekly, provided the recovery run pace is relaxed enough — it is far too common to do a lot of moderate runs and moderate workouts so that the weekly volume of running looks impressive, but there is a big cost to this approach, namely the athletes reach a competitive plateau quickly and/or risk injury or burnout.

Bowerman, Canova, and elite Kenyans all understand the importance of hard/easy. American coaches typically pay it lip service, as the common reality in practice is that the hard days aren’t hard enough and easy days aren’t easy enough, thus everything is kind of hard all the time — a recipe for disaster! 

Hope this helps clarifies your thinking.

Good luck this season to you and your team!

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Thx | @jmarpdx