The principle of reversibility of training (detraining) states that gains from training will be lost if training volume, intensity, or frequency is reduced too dramatically or stopped completely. While still believe that the overwhelming bulk of conditioning is done during the off-season, this practice is out-dated and ensures that fitness and physical capacity are at their lowest at the time when they need to be highest (at the end of the season). Physiological markers of fitness and performance can drop off with as little as 5 days of deconditioning. 5 days…that’s a long weekend holiday. To many readers of this site, that’s not new news. What most people don’t realize is that the time frames for detraining of various physical capacities degrade at different rates. Here’s a quick detraining timeline:
- Days 1-2: Beta-endorphin and adrenaline levels drop. Mood is affected negatively.
- Days 3-5: Muscles lose elasticity. Aerobic capabilities drop off 5% by the fifth day off.
- Days 7-9: Body’s ability to use oxygen (VO2 max) drops by 10%. Less oxygenated blood is pumped with each beat.
- Day 10: Body’s metabolic rate begins to drop. Eat less or you’ll gain weight.
- Days 11-13: Maximum heart rate and cardiac output decline by 15%. Muscle tone sees first appreciable loss.
- Days 14-16: Mitochondrial activity (energy production) in muscle cells begins to decrease rapidly. Loss of muscle mass, strength and metabolic rate occurs.
- Days 17-19: Body becomes less efficient at thermoregulation. You are forced to spend excess energy cooling off.
- Days 20-21: VO2 max has dropped by about 20%.
- Days 22-25: 10-15% loss of muscle mass and that lost mass is replaced by fat.
- Days 27-29: Muscle strength drops by as much as 30%.
These are general figures based on complete cessation of training and the time frames will vary on an individual basis based on the person’s physiology, their prior training history and what they are doing in the mean time to maintain the various physical capacities. The good thing is that most of these physical capacities can be maintained with relatively infrequent ‘refreshers’ and knowing the time frames of degradation for the various physical capacities will give you useful information on what type of loading you will need to do to maintain your hard earned gains.