Self selected speed and maximal lactate steady state speed in swimming.

AIM: The purposes of this study were to ascertain whether physiological and stroking parameters remain stable during a 2-hour exercise performed at self-selected swimming speed (S4) and whether this speed corresponds to those associated with the maximal lactate steady state (SMLSS). METHODS: Ten well-trained competitive swimmers performed a maximal 400-m front crawl test, 4 30-min swimming tests in order to determine S(MLSS) and a 2-hour test swum at their preferred paces to determine self-selected swimming speed (S4), stroke rate (SR4), and stroke length (SL4) defined as the mean values observed between the 5th and the 15th min of this test. The stroking, metabolic and respiratory parameters, and ratings of perceived exertion (CR10) were reported throughout the 2-hour test. RESULTS: S4 and SMLSS were not significantly different and were highly correlated (r=0.891). S4 and SL4 decreased significantly after a steady state of 68 min and 100 min, respectively, whereas SR4 remained constant. Mean VO2, dioxide output, and heart rate values did not evolve significantly between the 10th and 120th minute of the test whereas capillary blood lactate concentration (La) decreased significantly (p<0.05). Moreover, respiratory CR10 did not evolve significantly between the 10th and the 120th minute of the test whereas general CR10 and muscular CR10 increased significantly. CONCLUSIONS: Considering the (La), SL4 and CR10 values variations, muscular parameters and a probably glycogenic depletion seem to be the main limiting factors that prevent maintaining the self selected swimming speed.

Critical swimming speed does not represent the speed at maximal lactate steady state.

Critical power and critical swimming speed (CSS) are mathematically defined as intensities that could theoretically be maintained indefinitely without exhaustion. Several investigations have been conducted to attribute a physiological meaning to these variables, but results in swimming remain equivocal. Thus, the purpose of this study was to compare CSS with direct determination of the speed at maximal lactate steady state (S (MLSS)). Eight well-trained swimmers (aged 18.6 +/- 1.9 years) performed four tests to exhaustion (95, 100, 105, and 110 % of maximal aerobic speed [MAS]) in order to determine CSS from the distance-time relationship. S (MLSS) was determined from four sub-maximal 30-min constant intensity tests (ranging from 75 % to 90 % MAS). CSS (92.7 +/- 2.6 % MAS) was significantly higher than S (MLSS) (88.3 +/- 2.9 % of MAS) and the bias +/- 95 % limits of agreement for comparisons between CSS and S (MLSS) (0.07 +/- 0.13 m x s(-1)) indicated that the extent of disagreement was too great to use these two variables interchangeably. However, CSS and S (MLSS) were strongly correlated (r = 0.87; SEE = 0.033 m x s(-1); p < 0.01). Results from the present study demonstrate that in swimming, CSS does not represent the maximal speed that can be maintained without a continuous rise of blood lactate concentration and direct determination of S (MLSS) is necessary if precision is required in experimental studies.

Stroking parameters in front crawl swimming and maximal lactate steady state speed.

In order to increase or maintain speed at sub-maximal intensities, well-trained swimmers have an increase in their stroke rate, thus a decrease in their stroke. The purposes of this study were i) to ascertain whether the maximal speed from which the stroke length decreases significantly (SSLdrop) corresponds to the maximal lactate steady state swimming speed (SMLSS), and ii) to examine the effect of the exercise duration on the stroking parameters above, below, and at SMLSS. Eleven male well-trained swimmers performed an all-out 400-m front crawl test to estimate maximal aerobic speed (MAS) and four sub-maximal 30-min tests (75, 80, 85, and 90 % MAS) to determine SMLSS and SSLdrop and to analyse the evolution of the stroking parameters throughout these tests. SMLSS (88.9 +/- 3.3 % MAS) and SSLdrop (87.3 +/- 4.5 % MAS) were not significantly different from each other (p=0.41) and were highly correlated (r=0.88; p <0.001). Moreover, a slight stroke rate increase, and a stroke length decrease, were observed above S (MLSS) but were only significant for the 5 swimmers unable to maintain this speed for 30 min (p >0.05). During the 30-min tests swum below and at SMLSS, a steady state of stroking parameters was statistically reported. Thus, SMLSS seems to represent not only a physiological transition threshold between heavy and severe sub-maximal intensities but also a biomechanical boundary beyond which the stroke length becomes compromised.