The effect of rest days on injury rates.

Despite the importance of recuperation, few have studied the impact of rest periods on injury prevention. We determined the effect of rest days (breaks) on injury rates and treatments using electronic injury records from an acrobatic circus company that employs former world-class athletes as acrobats. To account for accumulated fatigue, we considered breaks across SD3 (third consecutive week of 1-day rest) to SD6 as a single exposure level (SD3-6), and vacation and DD (2-day rest) as a single exposure level. Medical attention injury rates were increased post- vs pre-break {rate ratio 1.45 [95% confidence intervals (95% CI): 1.22-1.73]} with less of an effect for 1-day time loss [1.25 (95% CI: 0.58-2.67)] and 15-day time loss [1.10 (95% CI: 0.26-4.56)]. However, the increase in injury rate post break for SD3-6 was similar to that of DD-Vacation (P=0.48, 0.53, and 0.65) for medical attention, and both ≥1 day and ≥15 days time loss, respectively. The increase in the number of treatments post-break was less for SD3-6 vs DD-vacation. Our findings suggest that 2-day breaks every four to 6 weeks may be sufficient to avoid an increasing injury rate due to cumulative fatigue in professional acrobatic circus artists.