Knizia, K., Gastman, U., Netzer, N., & Steinacker, J. M. (1997). Monitoring high-intensity endurance training using resting hematological, blood-chemical, and serum/plasma endocrinological parameters. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 1267.

The hypothesis tested was that changes in resting hematological, blood-chemical, and endocrinological parameters can indicate an early stage in the overtraining process during high-intensity endurance training.

Ss (N = 6) participated in 40-60 min/d, six times per week, for six weeks. Total training was 5-7 times greater than normal activity.

Submaximum and maximum power output increased for three weeks and then either stabilized or deteriorated over the remainder of the study period. No overcompensation was evidenced after regeneration but rather, a decrease in maximum power output was demonstrated indicating an early stage of the overtraining process. An extensive inventory of blood and endocrinological tests failed to reflect the onset of overtraining. Only serum ferritin and glucose levels were related to the changed state.

Implication. Hematological and endocrinological measures are not sensitive to the onset of an overtrained state. Only serum ferritin and glucose levels seem to have any relationship with the change of condition.

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