Training - Overtraining. A Prospective, Experimental Study with Experienced Middle- and Long-Distance Runners*

Abstract

Overtraining may be one frequent cause of stagnation or decrease in performance capacity of athletes. Israel (19) differentiates between addisonoid (parasympathetic) and basedowoid (sympathetic) overtraining, characterized by inhibition or excitation. We tried to induce an overtraining syndrome in 8 experienced middle- and long-distance runners, based on an increase in training volume from an average 85.9 km (week 1) to 115.1 km (week 2) and 143.1 km (week 3) to 174.6 km per week (week 4). The influence of this training on cardiovascular, metabolic and hormonal parameters was examined with special respect to plasma and urinary catecholamines. Laboratory testing including graded treadmill running was performed on the days 0, 14 and 28. Training was held six days each week, with nearly 30 km per day in the fourth week. A stagnation in endurance performance capacity (running velocity at the aerobic-anaerobic transition range) and a decrease in maximum working capacity were observed in 6 and a stagnation in 2 of the 8 sportsmen, indicated by a decrease in total running distance from 4719 + 912 m to 4361 + 788 m during incremental treadmill ergometry. The sportsmen could neither improve nor could they even approximately reach their personal records during the subsequent competitive season. Subjective complaints, classified on a four-point scale, increased from 1.2 (week 1) to 3.2 in week 4. Glucose, lactate, ammonia, glycerol, free fatty acids, albumin, LDL, VLDL cholesterol, hemoglobin level (transient), leukocytes, and heart rate (before and during exercise) decreased significantly. Urea, creatinine, uric acid, GOT, GPT, gamma-GT, serum electrolytes (except phosphate and calcium) remained constant at the measuring times, CPK was elevated. Noradrenaline plasma levels increased at the same submaximum workload during treadmill ergometry. Basal, nocturnal urinary catecholamine excretion (dopamine, noradrenaline, adrenaline) fell to 28-30%, the 24-h cortisol excretion to 70% of baseline values. There was a correlation between the decrease in urinary noradrenaline excretion and the complaint index (r = 0.91; adrenaline r = 0.79; dopamine r = 0.62, p < 0.10). In our opinion, the increase in exercise-induced noradrenaline plasma levels during treadmill ergometry combined with a 70% decrease in basal urinary catecholamine excretion may be of diagnostic relevance in short-term overtraining. The mosaic of the other findings cited can support the diagnosis.

Key words

Training - overtraining - metabolism - catecholamines