It seems that coaches are becoming increasingly aware of the importance of monitoring and managing fatigue in athletes. This is because fatigued athletes are at greater risk of being injured in addition to performing sub-optimally. Various techniques for assessing fatigue have been developed. Performance tests like drop jumps, counter movement jumps and sub-maximal bar velocity have been used. In addition, more invasive measures involving blood sampling for creatine kinase (a marker associated with muscle damage), C-reactive protein (a marker of inflammation) and testosterone to cortisol ratio have been studied. Heart rate measures like HRV and subjective measures such as Wellness questionnaires also show promise. Ultimately, the monitoring strategy used by a team must be practical, affordable and valid (sensitive to fatigue and performance).
Some interesting new research on the recovery status of reserve English Premier League players (U-21) following competition was just published ahead of print in the Journal of Strength and Conditioning Research. Over the course of 4 matches, the researches measured peak power output from counter movement jump tests in addition to blood creatine kinase levels at 24 hours before the match (baseline) and again at 24 and 48 hours after the match. The sample included 14 players who played a minimum of 60 minutes per match.
When compared to baseline measures, peak power output from the counter-movement jump tests were 237 ± 170 w and 98 ± 168 w lower at 24 and 48 hours, respectively. These values were each significantly different from baseline. Creatine kinase levels were elevated +334.8 ± 107.2 and +156.9 ± 121 at 24 and 48 hours, respectively, compared to baseline and were also significant. These responses were consistent across all 4 matches in that peak power output and creatine kinase levels reached lowest and highest levels, respectively at 24 hours post-match and though improved, remained well below baseline at 48 hours. A large and significant inverse correlation was found between peak power and creatine kinase. This indicates that as peak power decreased, creatine kinase tended to increase.
Based on these results, the authors suggest that both recovery status markers assessed in the current study appear to be effective at monitoring fatigue in athletes. They also suggest that the measurement of peak power from counter movement jumps may suffice, particularly when blood analysis is unaffordable or inaccessible for teams. The results also indicate that 48 hours is likely not sufficient for full recovery from match play and therefore training must be planned accordingly. Heavy training should possibly be reserved for 72 hours post-match, however this will depend on the competition schedule.
Russel, M., Northeast, J., Atkinson, G., Shearer, D. A., Sparkes, W., Cook, C. J., & Kilduff, L. (2015). The between-match variability of peak power output and Creatine Kinase responses to soccer match-play. Journal of Strength and Conditioning Research. Ahead of print.