We all know that fitness/strength/conditioning takes so long to build to a desirable level, but is so frustratingly quick to decline if we miss a period of time through illness, injury, holiday, off season etc. The million dollar question is: “How much fitness will I lose and how quickly will this happen if I have time off?” Perhaps equally as important is the question asking “how long it will take to build back up to my previous level after a lay-off”? Well, there’s been some recent evidence that helps provide answers to the questions surrounding what we call “The Detraining Effect”!

Ever wondered why you have been sent away over an off season with a pretty rigorous program of fitness and conditioning – just at the time when you were looking forward to a complete break? Why is it that AFL footballers (who only get a 6 week break over a 12 month period) are expected to return to the first session of pre season training in reasonable shape? And why do we as physio’s harp on about the importance of building strength and conditioning prior to surgery, or getting to the pool (which you may well hate) during a period when you can’t run? Well … it’s because we know that loss of conditioning can be quite rapid and dramatic, and even a small amount of modified training will help reduce this detraining effect.

In one of our greatest physio challenges, we are often faced with a patient who has been immobilised in a moon boot for 6 weeks, or a patient who has been in a sling for 4 weeks, or a patient who has had 3 weeks off training after sustaining a hamstring injury, and guess what… all expect to be back to sport in a week or two! The Detraining Effect explains why there are enormous risks coming back too soon!

What Is Detraining?
The purpose of training in any capacity is to get our tissues (muscles, tendons, ligaments, cartilage, bone) to slowly adapt to more load, more stress, more speed, more distance – whatever the demand we are putting on that particular part of our body. When we train, we adapt. And when we don’t train, the tissue simply maladapts (or loses its ability to withstand the stress being placed on it) and to put it simply:

the speed of this detraining effect is “frightening”!

Detraining not only occurs with complete layoffs (absolute rest) but also when not able to train at the same level we have been eg illness/injury/holiday (relative rest). The real problem is that we try and resume training at, or near, the level we were at prior to the rest, without realising how quick and extensive this detraining can be, and how much injury risk it subsequently places on our body.

In one article, it is suggested the following would take place if a previously fit cyclist “put the bike in the shed” for a period of time (eg a complete rest from training):

  • Day 3 (post final training session)
    The losses at this stage tend to be very small. In fact for those training very hard, after three days of rest, their fitness may actually be enhanced as muscles have recovered from the training and carbohydrate/glycogen stores have been topped up.
  • Day 7 (Week 1)
    After a week’s complete inactivity, the detraining effect has begun – in fact the blood volume can be reduced by five to 12 per cent. The heart has less blood to pump and by this time the muscles also can’t absorb the glucose (fuel) in the same capacity they can when conditioned.
  • Weeks 2-3
    At this stage, the prime measure of your aerobic fitness (VO2 Max – the amount of oxygen you can take in during exercise) will have declined by anything from four to 20 per cent. Your heart simply won’t have the same amount of available oxygen to pump to the muscles to produce the same outcome it previously could. Your training session will seem significantly harder. Your muscles will tire earlier in the training session.
  • One month
    Whilst all the figures above continue to decrease, the blood flow to your muscles has pretty much returned to your pre-training baseline and the muscle mass is also declining (reducing your maximum power and strength).

In a study on endurance athletes (recreational marathon runners, running an average of 51km per week in their marathon training; but reducing to less than 6km per week post marathon) similar outcomes were found: by four weeks of markedly reduced training, their blood/plasma volume had decreased 3.6% and the left ventricle of the heart (the pumping chamber) had decreased in mass and thickness.

So within a month of cessation (or near cessation) of training, some pretty dramatic detraining effects occur. And a sudden return to intensive exercise leaves us at markedly greater risk of injury.

To help us understand the relationship between length of rest time and time taken to return to full training, the AIS have produced a great table:

(Source: http://runpure.com.au/wp-content/uploads/2016/02/AIS_White_paper_-_Loads_and_risks_following_troughs250615.pdf )

To understand this graph, look at the following two examples from the table above:

  1. If you are unable to train at all for two weeks (0% on the X axis of the graph/ 2 on the Y axis), it will take you an additional 4.6 weeks to return to your previous training state. Including the 2 weeks of complete rest, that’s 6 weeks from stopping training to regain your fitness.
  2. In contrast, if you are able to maintain 80% of your normal training loads over the same two weeks (and this may come from cross training alternatives), it will only take 0.4 of a week (2.4 weeks in total) to return to full fitness.

So this table shows clearly that the ability to continue some form of training or conditioning during rest or injury periods, will dramatically reduce the time it takes to return to full fitness, along with greatly reducing your injury risk on return!

The take home message:

In Part 2 of this blog, we’ll look at the other great cause of injury – a sudden spike in training! In this article we’ve outlined the risks of rest followed by resumption of activity, but in part 2 we’ll look at the injury risk when a fit athlete simply does too much in one training session!

Remember, no matter what your hurdle, at SSPC “We’ll get you moving again”.

Anthony Lance

SSPC Physiotherapist

References available on request