Lehmann, M., Wieland, H., & Gastmann, U. (1997). Influence of an unaccustomed increase in training volume vs intensity on performance, hematological and blood-chemical parameters in distance runners. The Journal of Sports Medicine and Physical Fitness, 37, 110-116.

Whether hematological and blood chemical parameters could serve as markers in the early stages of overtraining was assessed. Overtraining occurs when the stress of all training and non-training factors exceeds recovery opportunities. Carbohydrate deficit, catabolic-anabolic imbalance, sympathetic-parasympathetic imbalance, and amino-acid-imbalance have been established to explain some pathogenic mechanisms in overtraining. Short-term overtraining (overreaching) is not usually a serious problem unless the symptoms are mistaken and training load is increased in an attempt to overcome them. Accidental or prolonged overreaching can cause overtraining.

Experienced distance runners (N = 8) were subjected to an unaccustomed 103% increase in training volume over four weeks. One year later 9 runners were subjected to a 152% increase in training intensity for activities. Seven athletes participated in both studies.

However, there was no single blood facet that could be used to indicate overtraining in all Ss. Only when performance and particular blood reactions are taken together for individuals can overtraining be better diagnosed.

Implication. Blood changes do occur with overtraining but no one indicator is useful as a universal diagnostic factor. Normally, a group of "unusual" levels in some blood factors along with diminished performance is adequate to diagnose an overtrained state. Overtraining, can be avoided by interpreting overreaching as a first stage breakdown rather than questioning whether reduced performances in overreaching are caused by a lack of effort, intestinal fortitude, or inadequate "mental toughness."

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