Lactate minimum is valid to estimate maximal lactate steady state in moderately and highly trained subjects

Some evidence exists that the determination of maximal lactate steady state (MLSS) with lactate minimum (LM) in highly trained athletes is not as accurate as in less trained athletes. Therefore, we compared power output at LM with power output MLSS in moderately up to highly trained subjects. 63 subjects performed a test on a cycle ergometer to determine power output at LM and 3 or more constant-load tests of 30 minutes to determine power output at MLSS. Mean power output at LM (245 ± 29 W; mean ± SD) was slightly lower than power output at MLSS (255 ± 32 W). The correlation between power output at MLSS and LM was high, and the regression line runs parallel to the line of identity showing that the results of highly trained subjects agree with the results of less trained subjects (LM and MLSS r = 0.867, p < 0.001). The modified blood-lactate kinetic in highly trained athletes compared with less trained persons does not impair accuracy at LM. Therefore, we suggest LM as a valid and meaningful concept to estimate power output at MLSS in 1 single test in moderately up to highly trained athletes

Feed restriction and a diet's caloric value: The influence on the aerobic and anaerobic capacity of rats

<p>Abstract</p> <p>Background</p> <p>The influence of feed restriction and different diet's caloric value on the aerobic and anaerobic capacity is unclear in the literature. Thus, the objectives of this study were to determine the possible influences of two diets with different caloric values and the influence of feed restriction on the aerobic (anaerobic threshold: AT) and anaerobic (time to exhaustion: Tlim) variables measured by a lactate minimum test (LM) in rats.</p> <p>Methods</p> <p>We used 40 adult Wistar rats. The animals were divided into four groups: <it>ad libitum </it>commercial Purina^®diet (3028.0 Kcal/kg) (ALP), restricted commercial Purina^®diet (RAP), <it>ad libitum </it>semi-purified AIN-93 diet (3802.7 Kcal/kg) (ALD) and restricted semi-purified AIN-93 diet (RAD). The animals performed LM at the end of the experiment, 48 h before euthanasia. Comparisons between groups were performed by analysis of variance (p < 0,05).</p> <p>Results</p> <p>At the end of the experiment, the weights of the rats in the groups with the restricted diets were significantly lower than those in the groups with <it>ad libitum </it>diet intakes. In addition, the ALD group had higher amounts of adipose tissue. With respect to energetic substrates, the groups subjected to diet restriction had significantly higher levels of liver and muscle glycogen. There were no differences between the groups with respect to AT; however, the ALD group had lower lactatemia at the AT intensity and higher Tlim than the other groups.</p> <p>Conclusions</p> <p>We conclude that dietary restriction induces changes in energetic substrates and that <it>ad libitum </it>intake of a semi-purified AIN-93 diet results in an increase in adipose tissue, likely reducing the density of the animals in water and favouring their performance during the swimming exercises.</p