Objective: To study whether field performance tests can make a valid distinction between non-functionally overreaching (NFO) athletes and control athletes.
Design: Monthly field performance tests were used to determine a performance decrement (PD) throughout a season. Athletes with a minimum of 1 month PD were compared with control athletes without a PD on mood characteristics and resting levels of stress hormones.
Setting: Sporting field and sports medical laboratory.
Participants: 129 young elite athletes, 77 soccer players and 52 middle-long distance runners were followed prospectively during the 2006-2007 season. Fifteen of them were invited to the laboratory. Eight athletes showed a performance decrease lasting longer than 1 month, and seven athletes without a performance decrease acted as their controls.
Main outcome measures: Performance changes over time were measured using field tests. Profile of Mood States and resting levels of adrenocorticotrophic hormone (ACTH) and cortisol in blood were measured in the laboratory.
Results: PD athletes showed several symptoms typical of the non-functional state of overreaching (OR). The PD group scored higher on depression and anger than controls. They also showed a specific pattern of correlations between negative mood subscales (tension, fatigue and depression), which was absent in controls. ACTH levels at rest were similar, but lower cortisol levels in PD athletes pointed at a blunted cortisol response. Cortisol levels were decoupled from ACTH levels only in PD athletes.
Conclusions: Implementing performance-related criteria in field tests can help coaches and sports physicians to distinguish NFO athletes from athletes with balanced workload and recovery.