Typical soccer seasons have periods of intense training, matches, tournaments and also rest periods at whatever level of football. As coaches we should be aware of the effects of training and also not training in order to best plan our seasons for optimal performance. Also refer to Periodization in Soccer. For the purpose of this article 'detraining' is referred to as the loss of training induced adaptations, as a result of insufficient training stimulus (Mujika I, 2000). Football performance can be defined as the loss of the following athletic attributes/components (discussed below). For the purpose of researching the components that integrate into soccer performance they are seperated. Their importance is subjective to the reader. In a number of cases were draw associations from other 'similar' sports where quantatative research in football is not available. Most stuides and research are showing that a 2-3 week period in the absence of training will not affect performance in the more important physical components of soccer.
Aerobic Endurance (Energy Systems)
Arguablity the most important physiological component to soccer is aerobic endurance. Maximal oxygen consumption was reduced significantly after 8 weeks of detraining (semi professional footballers)(Caldwell, BP, 2009). Figure 1 below shows the effects in generic sports training to detraining over a period of 84 days and factors influencial in Aerobic Endurance. Studies have shown that at various periods of a season a players anaerobic threshold will be different (i.e. showing the effect of training and games on a player)(Clark, NA, 2008). As expected pre-season anaerobic threshold values were the lowest. Enzymes important in this process can take several months to return to a baseline level following 3 months or more of detraining. Studies in Spain showed detraining of 4-8 weeks from muscle biopsies showed reduced Type 1 and Type 2 muscle fibres and enzymes that are important aerobic and anaerobic endurance.
Fig 1. Effect of training cessation on the physiological determinants of maximal oxygen uptake (VO2max). Q: cardiac output; a-vDO2: arteriovenous di4erence in oxygen; SV: stroke volume; HR: heart rate. Adapted from the data reported by Coyle et al. (1984).
Sprint times significantly increased (times increased) in 50m sprint tests in professional footballers (Ostojic, SM, 2003).
8 weeks of detraining between seasons resulted in significantly higher 15m sprint times in the Illinois Agility Test (Caldwell, 2009).
8 weeks of detraining resulted in reduced flexibility in lower back and hamstring muscle groups (Caldwell, 2009).
8 weeks of detraining resulted in increased body fat levels of semi-professional and professional footballers (Caldwell, 2009)(Hoshikawa, Y, 2004).
12 weeks of detraining resulted in significantly reduced strength/power gains in youth players (Ingle, L, 2006). A study showed that an average decrease of 14.5% strength after an 8 week detraining period. It appears strength losses occur after a 2-3 week period in some studies and a 4 week detraining period in another (Cormie, P, 2011).
The psychological benefits from detraining (rest periods, off-season) are less well researched and are difficult to provide quantative research for. But it looks safe to assume that 2-4 week break periods will not affect performance. Greater than 4 weeks and the affect of detraining with start to show in various components of physical fitness.