The evidence suggesting a lack of recovery impacts sporting performance is both clear and abundant.
We know from studies that lack of recovery time has a dramatic impact on injury rates in sport. Most of the research comes from the team sports world, with football and rugby featuring prominently. The data is clear that under-recovery caused in part by a lack of sleep has a significant impact on the predictability of sports injuries .
When we explore the topic further, we can look at what the evidence says about rest required to maintain physical performance. For sprint-based sports such as football, the evidence suggests that 72-96 hours are sufficient for physical recovery from a performance standpoint, but not for reducing injury risk. The most alarming statistic from the study shows that playing twice per week as opposed to once per week dramatically increases injury frequency - 25.6 versus 4.1 injuries per 1000 hours of exposure .
These studies show us that under recovery increases injury risk, but what is the direct impact on lack of recovery on performance?
In this 2011 study sleep and the impact on athletic performance were studied . The subjects were the Stanford University Men’s Basketball team. The participants in the study underwent physical and skills tests in different stages of sleep deprivation. The results showed that with sufficient sleep, athletes were able to improve sprint times (16.2 ± 0.61 sec at baseline vs. 15.5 ± 0.54). Their shooting accuracy also improved by 9.2%, showing there’s a cognitive and skills improvement through recovery.
These results are further supported by evidence found in a study by Waterhouse et al , where athletes improved their 20m sprint time from 3.971 s to 3.878 s. While this might seem insignificant, in a sporting context it’s a dramatic difference.