Abstract
Non-functional overreaching (NFO) and overtraining Syndrome (OTS) result in impaired performance. Using biomarkers, it may be possible to detect early indications of these before deteriorations occur. PURPOSE: Evaluate changes in predictive biomarkers of NFO & OTS in female collegiate power-endurance athletes during the season and relate these changes to preseason fitness. METHODS: Division I female soccer & field hockey athletes (N=53, Mweight = 64.5 ± 6.9 kg; M%BF = 23.9 ± 5.7%; MVO2MAX = 47.6 ± 5.0 ml/kg/min; MVJ = 54.5 ± 7.4) participated in preseason fitness testing. Tests included body composition, vertical jump (VJ), VO2MAX & ventilatory threshold (VT). Blood was drawn at the start of preseason and 8 weeks later at midseason. The athletes arrived for blood draws in the morning in a euhydrated, fasted condition. Markers included insulin (IN), IL6, creatine kinase (CK), cortisol (CORT), prolactin (PRL), T3 & T4. RESULTS: IN (7.1 ± 2.9 vs 5.0 ± 4.6 uIU/ml) and T4 (1.2 ± .2 vs 1.1 ± .1 ng/dl) significantly decreased (P<.05), while IL6 (1.2 ± .6 vs 1.6 ± 1.3 pg/ml), CORT (25.2 ± 11.3 vs 30.4 ± 11.9 ug/dl), and PRL (14.1 ± 7.9 vs 18.5 ± 9.2 ng/ml) significantly increased (P<.05). Additionally, there were trends for increased CK (116 ± 106 vs 152 ± 110 U/L, P = .061) and T3 (108 ± 23.9 vs 113 ± 24.2 ng/dl, P = .072). Correlations for fitness measures and changes in biomarkers revealed significant associations between VT and T4, r = .506, P<.05, and LBM and CORT, r = .454, P<.05. Regression analyses revealed VT, VJ, and VO2MAX predicted 14.3% of variability in CORT (P<.05), with the largest predictive ability attributed to VO2MAX alone (R2 = .14, P<.05). Fitness also accounted for a considerable (R2 = .29, P<.05) amount of the variability in PRL while %BF also predicted changes in PRL (R2 = .18, P<.05). In all cases, higher fitness was associated with greater changes in biomarkers. CONCLUSION: Intense training without adequate rest leads to increased muscle breakdown, inflammation and stress as the body enters a more catabolic state. This is met with elevated metabolism to expedite recovery. Fitter athletes likely play more and receive less rest, so early detection of NFO symptoms through biomarkers may be a particularly useful monitoring strategy. Sponsored by Quest Diagnostics
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