This study investigated fatigue-induced changes in neuromuscular and stride characteristics during and immediately after the 5-km running time trial. Eighteen well-trained male distance runners performed a maximal 20-m sprint test and maximal voluntary contraction (MVC) in a leg press machine before and immediately after the 5-km running time trial. In all the tests the EMG of five lower limb muscles was measured. The results of the present study showed that muscle fatigue measured in maximal exercises like 20-m sprint and MVC are not related to the fatigue induced changes during the 5-km time trial. The fatigue in the 20-m sprint test was related to the maximal 20-m pretest velocity (r=0.58, p<0.05), but the velocity loss during the 5-km time trial was inversely related to 5-km performance (r= - 0.60, p<0.05) and training volume (r= - 0.58, p<0.05). It was concluded that the fatigue in 5-km running measured pre- and postexercise at maximal effort is more related to sprint performance rather than endurance performance, but the fatigue measured during the 5-km running is related to endurance performance and factors affecting pacing strategy.

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The aerobic and anaerobic thresholds determined from venous lactate (AerTLa and AnTLa) or from ventilation and gas exchange (AerTr and AnTr) in relation to muscle fiber composition were compared. Twelve subjects were studied in double exercise tests carried out until voluntary exhaustion. They were divided into two groups according to their muscle fiber type in the vastus lateralis muscle: ST group with a majority of slow-twitch fibers (ST% = 66.0% +/- 7.3%) and FT group with a majority of fast-twitch fibers (ST% = 27.7% +/- 8.4%). A 2-min incremental exercise test protocol on a bicycle was used. There were no significant differences between the ST and FT groups in the VO2max or in the Lamax. Neither the AerT nor the AnT related to the VO2max (%) differed between the ST and FT groups. In the FT group the AnTLa occurred 0.70 min in the first test and 1.06 min in the second test earlier than the AnTr, whereas in the ST group the AnTLa occurred at the same time or 0.44 min later, respectively, than the AnTr (P less than 0.05). Expressed as VO2 the differences between thresholds were not so distinct. The results demonstrated that the mutual relation between the AnTLa and AnTr seemed to be dependent on the fiber type majority in exercising muscles (vastus lateralis) among untrained men.

Three different modes of lactate tests were studied. Eleven male competitive swimmers performed the tests (n.100 m, n.300 m, 2.100m + 2.400 m) within 5 days. Swimming velocity (V) vs blood lactate (BLa) and V vs heart rate (HR) curves were averaged. In V vs BLa comparisons, the BLa values of 4 mmol.l-1 in 2.400 m, 3 mmol.l-1 in n.300 m, and 2 mmol.l-1 in n.100 m modes were found to correspond to the same V. Although the resting BLa values were similar before the testing occasions, the initial BLa value in very easy swimming was lower in the n.300 m than in the n.100 m mode. The elimination of lactate most probably caused this difference. The highest BLa value was measured in the n.100 m (14.9 mmol.l-1) and 2.100 m (13.6 mmol.l-1) exercise modes demonstrating a higher rate of anaerobic energy production than in the n.300 m or 2.400 m test modes. In HR vs V comparison, the n.300 m and 2.400 m modes demonstrated similar HR values in relation to V. To measure the whole intensity area, a combination of tests should be applied by performing an incremental set with several steady-state loadings (aerobic) and one or two 100 m swims (anaerobic) in one test session.

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