Recovery Discussion: Is it important? Any evidence?

Posted on January 18, 2010


Thought some might find a conversation about recovery in sport amongst some exercise and sport scientists interesting. If nothing else, it highlights the controversey, and little understanding the science community has about the area.

At the moment I’m trying to prepare a grant application related to sport performance and recovery. The opening paragraph of my intial draft was:

A balance between training stressors and recovery are professed to be important in maximising the performance of athletes. Athlete training is generally based on a principal of progressive overload, in which the continual stress from adequate training stimulus leads to an adaptation process and subsequent improvement of performance. Although not well understood, it is thought that fatigue that prevents an athlete from performing at a perceived potential during training (generally based on a time and distance covered relationship) will result in suboptimal stress, and therefore reduced (is there any scientific evidence behind this idea??). Based on this understanding, recovery forms a crucial component of athlete preparation seeking peak performance.

So immediately I was looking for references to support that general understanding.

In fact most studies in the area make a similar comment, and I had noted that none of them were referenced. Normally you get a comment such as:

For example, it is a common belief that the flux through a metabolic pathway or a transport system may be a crucial factor determining subsequent adaptations in the contracting muscle (Bishop, 2009).

So I had a look, and couldn’t find any. There appears to be a basic premise to all the literature on recovery and periodisation which isnt supported by scientific evidence. I’m not claiming its wrong, just pointing out its not supported in science. So I sort out some colleagues to see what they could tell me.

Down the corridor at UCNISS I received comments that what I was looking for related to the theory of supercompensation (see Bompa) but actual evidence supporting this is very weak. Otherwise my peers couldn’t help, no actual evidence to support that fatigue detracts from Its probably important that I state there are ideas such as functional (relatively short-term overreaching) and non functional (essentially overtraining) forms of overreaching, or a fatigued state. I’m really only referring to the functional overreaching form. To put it in furter context, I really want the study to look at chronic cryotherapy use over an extended period (e.g. 3-4 x 20 min cold water immersions per week, post training, for a 4 week training block in middle distance runners).

There is no doubt that some aspects of fatigue and inadequate recovery can be bad. Training and performance will obviously suffer with injury and illness or depleted fuel reserves. But how does fatigue influence the stimulus for adaptation from a specific bout of training?

So I invited a few colleagues to a Skype conversation and this is the response (edited for space and a few lines are bolded to give you an idea of what each part of the discussion is focussing on):

Ben Rattray (BR): question i need help with. any scientific evidence that fatigue and subsequent training performance (e.g. speed) is important 4 adaptation and improvement?

it makes sense, but is there any evidence? imagine training a bit tired, you don’t run/ride quite as fast, but you try just as hard, and cardiovascular wise (HR), you might even get the same response. does the slower speed matter in terms of adaptation and improvement. chronic fatigue is a problem, but that is impeding on performance, what about fatigue impeding on training and the subsequent stimulus?
Tania Churchill (TC): Hmm… not sure if I can be of any help, but some initial thoughts: For a cyclist, fatigue decreases the amount of power than can be produced at the top end (not surprising, found one (Beelen & Sargeant, 1991). Conventional training wisdom is to not do sprint work when fatigued – not sure if there’s research on this though. It does make sense- if power output is lower due to fatigue, then the training stimulus will be different, even if RPE is similar to when the athlete is fresh.
BR: yer agree makes sense. but does the lower power output mean there is less adaptation? (makes sense that it does, but I cant find any evidence).

what confuses this more is the recent research that shows there was similar expression of oxidative genes after interval and continuous exercise (overall duraton and work held constant) (Wang et al, 2009).
another study – provided you eat enough, then it may not matter training a bit tired? this study probably isnt long enough, they werent actually fatigued yet (fast swims at same pace) (Costill et al, 1988).
TC: Hmm… It might depend on the type of training while fatigued. I haven’t found any studies on this yet, but if one goal of sprint training is to increase the efficiency of temporal sequencing of muscle activation, then presumably efforts at a lower speed wouldn’t have the same effect.
Ben Wisbey (BW): without reading all of the above and with no research to back it up, I would suggest that high speed training is important to improve performance. especially in running based sports (cadence can make it a little more complicated for cyclists). You might get the same CV etc load when training fatigued, or training with heavy shoes, or doing hill repeats but the adaptation (especially neuromusc) are different. From a practical perspective you see it all the time. Eg. you orienteers are run fit and ultra strong uphill, but on the flat, performance is relatively low
The benefits you get are relative to the training you do. You need to revisit Noakes principles [e.g. Noakes, 2000 and Noakes et al, 2005]
BR: yer no i agree, completely. and yes Noakes talks about it. But no [?] evidence is presented. perhaps you can draw inferences from literature on overspeed training. but its not really the same thing. for instance, if you are tired (neuromuscular speaking) and you train as fast as you can, the neuromuscular system may still be “working as hard” as when you are fresh and running a bit faster. so is this “as hard” bit providing an equivalent training stimulus?
the temporal sequencing is still happening, just not quite as fast, but does this matter in terms of training stimulus when its working “as hard”?
TC: This might be useful – Merlau, 2005 – bit hard to tell from the abstract
BW: you are right Ben, no evidence. Maybe a good project for you
From a practical point of view, I think it is commonly accepted that speed training can only be maximised when fresh.
Cyclists do high cadence work or motor pacing
Distance runners do downhill sprints
Sprints and team sport athletes do overspeed work
All to get improvements in speed. This can’t be achieved by running slow. Fatigued = slow.
Go research it and then tell us
BR: 🙂 so recovery is all important for speed and speed only?
BW: don’t understand the question. |-(
TC: Are other types of sessions (e.g. SE) still effective when fatigued?
BR: why do we get athletes so concerned about recovery if the only time it is important is when they are doing speed training?
BW: because speed (top end intensity) determines performance
Obviously recovery would be important for all sessions but the benefits of speed training dictate performance. Is a runner with a VO2 of 75 going to beat a runner with 70? Might help but only to a small degree. ??????? my opinions
BR: so im not clear on what you mean. you are saying, at the extreme, that Usian Bolt will beat Bekele in a marathon? clearly the top end intensity of these two athletes is very different. what do you mean my speed?
BW: sport relative speed
to run a marathon you need a base level of endurance. But beyond that base, is more better?
in cyclists and AFL players we have seen that a base level of endurance is required to perform well but above that and everyone is effectively similar. More is not better, but too little and performance suffers
BR: so if you are doing a session (flat, like on a track) you really need to be fresh for when you are running 110-130% race pace (say for a miler), but if you are doing a flat session at 80-100% race pace then recovery is less important. and its important because race specific speed is the most important part of performance.

so I’ve made up numbers, but is that your basic point?
BW: i would say you still need to be fresh at race pace otherwise you won’t be able to hit and sustain that type of pace
remember you race when you are fresh
you see it all the time when athletes training for long events do volume and their intensity work slows and their short race performance slows
BR: that last example is a training specificity issue, not necessarily a fatigue issue.

Halson et al (2002) is anoter study that doesnt quite look at the issue. but they show that training with a lot of fatigue for a few weeks (and performance drops), after a recovery period they perform back at at least the same level. so there is a suggestion here that training whilst fatigue did not alter performance (but they didnt improve either, but there is an underlying assumption in the paper that they are already trained and therefore didnt antiicpate improved performance anyway… always assumptions).
BW: but it is event specific
and performance isn’t going to change (up or down) substantially in athletes with a good training background
BR: yer that was my point, they are not likely to change anyway, but at least it suggests they didnt lose it even though they werent able to achieve the high power outputs.

event specific you mean cycling? and that doesnt relate to running?
BW: more mean that training while fatigued for a marathon is probably important for performance in some ways, while for a 800m, it is not
BR: ok, so recovery techniques for marathon runners are less important than for 800m runners?
TC: I think training for a long enduro race like a 24hr, some long aerobic sessions should be done while fatigued – but doesn’t mean recovery techniques are less important. Just means fatigue is manupulated in different ways throughout a training week to the way a trackie would.
BW: yer good point. larger volumes mean you are always fatigued. but recovery is still important so that you can still manage maximum volume
TC: exactly
BR: so what are recovery techniques doing then? why are they helpful?
(clearly some advantages such as ensuring fuel, keeping immune system functioning)

but what say is cryotherapy doing? none of them?
BW: reducing inflamation and pain and allowing you to do it all again sooner
BR: so pain has obvious consequences for the pyschology of going out and doing it again. some level of inflammation is necessary for adaptation. so is it all just for the head?
TC: Presumably reducing inflammation and pain would have a positive effect on reducing likelihood of over-use injuries during the next training session?
BW: i hate your questions Ben
slushies reduced core temp in the lab and froze the girls in China as it was cold and wet
BR: inflammation is complex, too much bad, too little bad.

pretty sure the jury is out on who to reduce chronic injuries apart from reduced load.

so I started this by asking what evidence is there that training whilst tired will result in less of an adaptation, presumably through a “reduced training stimulus as measured by performance (e.g. speed). so we are agreeing there isnt any really, and that logically it makes sense, and emperically it matters more for shorter events than longer events. the exception to this is that adequate recovery makes athletes feel better, and this is important.

sums it up?
TC: Pretty much. I think some evidence will be out there – but it will be in bit and pieces. E.g. there will be evidence on the adaptations triggered by sprint training. And evidence on at what intensities certain adaptations are or aren’t triggered.
And then there will be some stuff on periodisation. Doesn’t seem to be so many studies here – more books like Bompa’s (e.g. Bompa, 2009), which has lots of claims, but not much in the way of evidence.

So really we just concluded there was no evidence. There certainly seems to be a distinct lack of direct evidence, but inferences can probably be made from a range of studies, I have mentioned just two:

  • in highly trained endurance athletes, high intensity training appears to improve performance without changes in cardiovascular parameters (VO2max etc) (Laursen & Jenkins, 2002)
  • although, in relation to the above, high intensity training was shown to boost markers of oxidative metabolism, glycolysis and buffering capacity but with no improvement in performance – in rats (Laursen et al, 2007)

Admittedly since then I have found a couple, although the evidence is never direct. But that will have to wait for another post.

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