Saturday, December 19, 2009
The benefits of going 'easy'.
I received an interesting question via email this week that left me a little ponderous. Since pondering is always better shared, I thought I’d write a small piece on it for my blog this week.
The question was in reference to a recent literature review by Stephen Seiler on the polarization of training into definitive ‘hard’ and ‘easy’ training….
“It seems that you place a lot of emphasis on ‘steady’ training. I was wondering if you see a place for ‘easy’ training in the athlete’s basic week and if so, what benefits do you feel such training promotes?”
The reader is correct that I see very little direct benefit to training conducted below the aerobic threshold and A LOT of direct benefit to training conducted just above the aerobic threshold. However, this is not to say that there are no benefits to including easy training within your week. I’ll outline a couple of those here.
First a quick caveat that relates to the Seiler paper, and indeed to any comparison that a recreational athlete may make with an elite athlete’s physiological data:
Because elite athletes have greater central fitness, they have a diminished heart rate response for a given VO2max. Take for example, an ‘in-shape’ test for Gordo vs yours truly:
Gordo (60% VO2max) = 72% HR max
AC (60% VO2max) = 80% HR max
So, when looking at time within a given % HR range, for example when Seiler references that a large elite training volume is performed at 60-70% of HR max, keep in mind that a large chunk (probably half of this training) is likely at or above the aerobic threshold for folks with these sorts of engines (VO2maxes in the range of 5.0L+)
However, this does not discount the fact that a still significant portion of training is performed at a lower level than the aerobic threshold. If there is little physiological benefit to training below this magic number, why would these folks spend 500 hours per year or more doing so? Do they have too much time on their hands? While probably partially true there is benefit to spending some of your weekly hours noodling.
Easy training or, more precisely, recovery training is, in its purest form, training to train. Let me explain….
When an athlete has completed all of the quality training that they can muster and the energy tanks are empty they are left with 2 basic choices:
1. Grab some food and sit on the couch until you’re ready to go again
2. Grab some food and train easy until you’re ready to go again.
While, for the time limited athlete, the first strategy is probably not a horrible one (providing your couch time doesn’t extend into days :-), it is not optimal.
While the benefits of active recovery between intervals within a session are well known, i.e. marked increase in the reduction of lactic acid within the muscles, redistribution of blood pool etc, the benefits of easy/recovery training between key training sessions are less well understood.
One could probably postulate that moving more blood into the muscle will more quickly evacuate the debris associated with muscle damage and lead to an expedited healing. This is a core tenet of many physiotherapeutic modalities. However, there is much more ‘good stuff’ to be had than just speeding up the muscle healing.
Fundamentally, the primary physiological limiter that prevents athletes from getting up off the couch, out the door and into their next key workout is incomplete refilling of the muscle glycogen stores. Therefore, anything that will hasten this process will ultimately lead to more steady-state training within the athlete’s week.
So, this begs the question, ‘how in the world could expending more energy lead to getting energy back at a faster rate?’
It’s a fair question and one that has received mixed answers. For example, Choi et al., 1994 found that while active recovery was beneficial from the perspective of lactate dissipation, it did result in slower total glycogen replenishment than passive recovery. However……
When looked at on the muscle fiber level, it was found that this extra glycogen breakdown was coming from the relatively unused Type 1 muscle fibers while replenishment of the Type II fibers was marginally enhanced (Fairchild et al. 2003)
This makes intuitive sense when we recognize the fact that exercise is a significantly more potent stimulus for muscle glucose uptake than insulin - the stuff that is secreted when using the ‘sit on the couch’ methodology (James et al. 1985).
When you undertake light exercise (below the aerobic threshold) between your key sessions, you greatly increase blood flow and consequent glucose delivery to the muscle and you put the muscle in a much more receptive state to take up and use this glucose to replenish muscle glycogen stores than if you were sitting passively.
Additionally, easy training mobilizes energy from muscle fibers that are full of glycogen so they can be utilized by those fibers that are depleted, i.e. the athlete can ‘borrow’ energy from slow twitch fibers to use in fast twitch fibers (Brooks, 1985). Similarly, the athlete can borrow energy from unused muscle groups to pay the energy debt of exhausted muscles. For this reason, doing some cross-training using different muscles on your recovery days is a good practice.
By utilizing these forms of easy training, quicker between-key-session recovery takes place. It’s the old adage of ‘the more you do the more you can do’. Or put another way, the more ‘active’ your recovery, the more purposeful training you can get done each week.
This adage brings up a key condition and one that, in the quest for bigger logbook numbers, a lot of athletes miss – your easy training should result in you being able to do more steady training. It should support, not detract from your key workouts.
Yet again, it comes back to understanding the purposes of your workouts and sticking to them. It has been said that once you begin making your easy days a little too hard, it is a matter of time before your hard days become a little too easy. Hopefully understanding the whys of easy training will make the embarrassingly slow shuffle or the ‘granny gear’ spin a little easier for the ego to tolerate :-)