Abstract des Autors

The influence of low and high carbohydrate diets on the relationship between blood lactate concentration (Lac) and work load (WL) in incremental exercise tests (cycle ergometer) and endurance tests was evaluated in trained subjects. The relationship between relative work load (WLre1) and (Lac) in arterialized blood was compared in untrained subjects (UT) and trained male athletes (TR) after 2 days without training while consuming a high carbohydrate diet (HCD). In both groups (Lac) of 2 mmol/l was reached at about 60 ((mean +/- SD) UT 57.7 +/- 6, TR 62.7 +/- 3.8) and 4 mmol/L at about 75 (UT 75.2 +/- 3.6, TR 77.8 +/- 2.2) of the maximal work load (WLmax). In eight cyclists the relationship between (Lac) and WL was not influenced by a 13-day training camp; however, heart rate was lower after the training camp. During their normal training programme, trained subjects had high relative work loads at their (Lac) thresholds, but after an HCD combined with an interruption of the training of 3 days, the relationship between (Lac) and WLre1 was the same as in UT. In six TR a low carbohydrate diet (LCD) combined with training led to high absolute (WLabs) and WLre1 at (Lac) of 2 and 4 mmol/l; an HCD combined with 3 days without training led to low WLabs and WLre1 at the same (Lac) and to higher WLmax. In spite of the apparently lower endurance capacities TR were able to work significantly longer after HCD than after LCD (23 +/- 10.5 min and 49 +/- 16.2 min, respectively) at 65 of their WLmax. The variability of the relationship between (Lac) and WL following the dietary regimes leads to the conclusion that the typical (Lac) versus WL curve of endurance TR may result from a permanent glycogen deficiency.