Indices of Training Stress During Competitive Running and Swimming Seasons

Abstract

Eight male cross-country runners and five male swimmers were tested four times during their collegiate seasons. Each trial corresponded to a different training load. The runners' trials were conducted before the start of organized practice (RT1), after 3 wk of increased training (RT2), 3 wk prior to the conference championship (pre-taper, RT3), and 4 d after the conference championship (post-taper, RT4). The swimmers' trials were conducted after the first 9wk of training (ST1), after completing 2 wk of hard training (ST2), after an additional 6 wk of training (pre-taper, ST3) and during a week following the conference championship (post-taper, ST4). Venous blood samples, heart rate (HR) and blood pressure (BP) were obtained after 15 min supine rest (0700 h). Serum was analyzed for Cortisol (C), total testosterone (TT), free testosterone (FT), and creatine kinase (CK). Blood samples (lactate), HR and RPE were obtained during a fixed velocity run (75% preseason VChmax) and blood samples and RPE following a 365.8 m swim (90% preseason V̇O₂max). The runners then completed a “performance run” to exhaustion (110% preseason VO₂max) and the swimmers completed maximal 22.9 and 365.8 m swims. Serum CK, C, TT, FT, and the TT:C and FT:C ratios were not significantly different among trials for the runners. Serum TT and FT were significantly (P < 0.05) lower for the swimmers at ST2 (TT 16.7±2.5; FT 85.3±8.5) compared to ST1 (TT 30.3±2.8; FT 130.2±20.9) whereas, C, TT:C or FT:C were not significantly altered. Serum CK was significantly elevated for swimmers at ST2 (135.3±20.9) and ST3 (101.7±16.7) compared to ST1 (54.12±8.2). Performance capacity in 365.8 m and 232.9 m swims was significantly reduced at ST2 and returned to preseason times at ST4. Resting HR and BP were not significantly altered for either swimmers or runners. In conclusion, C, FT: C and TT: C were not influenced by changes in training volume/intensity in swimmers or in runners. Serum TT and FT were significantly reduced and CK significantly elevated when training was substantially increased for a short time period for the swimmers (ST2). Changes in TT, FT, and CK were concomitant with decreased performance and increased global mood state. Furthermore, TT and FT were increased, and CK decreased, when swim training volume was reduced (ST4). Therefore, TT, FT and CK may be effective markers for monitoring overtraining in athletes.

Key words

Staleness - overtraining - hormonal response - overtraining syndrome