INFLUENCE OF AN UNACCUSTOMED INCREASE IN-TRAINING VOLUME VS INTENSITYON PERFORMANCE, HEMATOLOGICAL AND BLOOD-CHEMICAL PARAMETERS IN DISTANCE RUNNERS

The hypothesis was tested that high-volume endurance training can be m onitored using hematological and blood-chemical parameters as markers of an early stage in the overtraining process, Eight experienced dista nce runners participated in a prospective, experimental, controlled st udy, The study consisted of an unaccustomed average 103% increase in t raining volume (ITV) within 4 weeks (average final volume: 174.6 km pe r week), A pear later, 9 runners performed the additional 4-week contr ol study that consisted of an unaccustomed average 152% increase in in tensive training measures (ITI), Average total volume amounted to 61.7 km (week 1) and 84.7 km (week 4), Seven athletes participated in both studies, Simultaneously to performance diagnostics, a comprehensive p attern of hematological and blood-chemical parameters was determined, During ITV, submaximum running performance was improved after 2 weeks, stopped improving between week 3 and 4; maximum performance did not i ncrease rather was decreased after week 4 compared to baseline as indi cation of an early stage in the overtraining process, During ITI, subm aximum and maximum running performances increased continuously, In con trast to ITI, the following parameters decreased significantly during ITV: White blood cell count, serum iron, ferritin,VLDL- (very low dens ity lipoproteins), LDL (low density lipoproteins)-cholesterol, albumin , resting and maximum free fatty acid, maximum lactate, resting, subma ximum and maximum glucose, summed amino acid, resting, submaximum and maximum ammonia concentrations, whereas prothrombin time increased sig nificantly. During high-volume endurance training a multifactorial and longitudinal approach considering either a performance incompetence a nd an individually different range of symptoms and alterations in hema tological and blood-chemical parameters can help to recognize an early stage in the overtraining process.