This study aimed at assessing the sensitivity of both maximal lactate steady state (MLSS) and critical power (CP) in populations of different aerobic training status to ascertain whether CP is as sensitive as MLSS to a change in aerobic fitness. Seven untrained subjects (UT) (maximal oxygen uptake = 37.4 ± 6.5 mL·kg(-1)·min(-1)) and 7 endurance cyclists (T) (maximal oxygen uptake = 62.4 ± 5.2 mL·kg(-1)·min(-1)) performed an incremental test for maximal oxygen uptake estimation and several constant work rate tests for MLSS and CP determination. MLSS, whether expressed in mL·kg(-1)·min(-1) (T: 51.8 ± 5.7 vs. UT: 29.0 ± 6.1) or % maximal oxygen uptake (T: 83.1 ± 6.8 vs. UT: 77.1 ± 4.5), was significantly higher in the T group. CP expressed in mL·kg(-1)·min(-1) (T: 56.8 ± 5.1 vs. UT: 33.1 ± 6.3) was significantly higher in the T group as well but no difference was found when expressed in % maximal oxygen uptake (T: 91.1 ± 4.8 vs. UT: 88.3 ± 3.6). Whether expressed in absolute or relative values, MLSS is sensitive to aerobic training status and a good measure of aerobic endurance. Conversely, the improvement in CP with years of training is proportional to those of maximal oxygen uptake. Thus, CP might be less sensitive than MLSS for depicting an enhancement in aerobic fitness.
New Findings What is the central question of this study?What role do neuromuscular fatigue mechanisms play in resistance training‐induced adaptations of the impulse above end‐test torque (IET) after the training period? What is the main finding and its importance?IET and global and peripheral fatigue were increased after a short period of resistance training. Thus, resistance training‐induced adaptations in neuromuscular fatigue seem to contribute to enhanced IET after the training period. Abstract Short‐term resistance training has a positive influence on the curvature constant of the power–duration relationship (W′). The physiological mechanism of W′ enhancement after resistance training is unclear. This study aimed to determine whether one‐leg maximal isometric resistance training influences (1) impulse above end‐test torque (IET; an analogue of W′) during a 5 min all‐out isometric test; and (2) exercise tolerance (limit of tolerance, Tlim) and neuromuscular fatigue during severe exercise (i.e. above end‐test torque; ET). Sixteen healthy active males participated in a 3‐week unilateral knee extensor resistance‐training programme, and 10 matched subjects participated as controls. The subjects were instructed to ramp up to 100% of maximal voluntary contraction (MVC) over 1 s, hold it for 3 s, and relax. Each repetition had a 2 s interval (10) and each set, a 2 min interval (3). MVC (18.6%) and muscle thickness (12.8%) were significantly improved after training. Significantly greater global (i.e. reduced MVC, 43.2 ± 13.5% vs. 58.9 ± 6.9%) and peripheral (51.7 ± 13.6% vs. 57.3 ± 15.3%) fatigue, IET (26%) and Tlim (92%) were obtained after resistance training. Moreover, both global (r = 0.57, P < 0.05) and peripheral fatigue (r = 0.55, P < 0.05) accrued during severe exercise were associated with IET. However, echo intensity, which reflects muscle quality, ET and central fatigue remained unchanged throughout the training period. No significant changes in the control group for any variable were observed. Resistance training‐induced adaptations in muscle size and neuromuscular fatigue seem to contribute to enhanced IET and Tlim after the training period.
The purpose of this study was to determine both the independent and additive effects of prior heavy-intensity exercise and pacing strategies on the VO2 kinetics and performance during high-intensity exercise. Fourteen endurance cyclists (VO2max = 62.8±8.5 mL.kg−1.min−1) volunteered to participate in the present study with the following protocols: 1) incremental test to determine lactate threshold and VO2max; 2) four maximal constant-load tests to estimate critical power; 3) six bouts of exercise, using a fast-start (FS), even-start (ES) or slow-start (SS) pacing strategy, with and without a preceding heavy-intensity exercise session (i.e., 90% critical power). In all conditions, the subjects completed an all-out sprint during the final 60 s of the test as a measure of the performance. For the control condition, the mean response time was significantly shorter (p<0.001) for FS (27±4 s) than for ES (32±5 s) and SS (32±6 s). After the prior exercise, the mean response time was not significantly different among the paced conditions (FS = 24±5 s; ES = 25±5 s; SS = 26±5 s). The end-sprint performance (i.e., mean power output) was only improved (∼3.2%, p<0.01) by prior exercise. Thus, in trained endurance cyclists, an FS pacing strategy does not magnify the positive effects of priming exercise on the overall VO2 kinetics and short-term high-intensity performance.
The purpose of this study was to analyze the effect of recovery type (passive vs. active) during prolonged intermittent exercises on the blood lactate concentration (MLSS) and work rate (MLSS(wint)) at maximal lactate steady state. Nineteen male trained cyclists were divided into 2 groups for the determination of MLSS(wint) using passive (maximal oxygen uptake = 58.1 ± 3.5 mL·kg(-1)·min(-1); N = 9) or active recovery (maximal oxygen uptake = 60.3 ± 9.0 mL·kg(-1)·min(-1); N = 10). They performed the following tests, on different days, on a cycle ergometer: (i) incremental test until exhaustion to determine maximal oxygen uptake; (ii) 2 to 3 continuous submaximal constant work rate tests (CWRT) for the determination of the work rate at continuous maximal lactate steady state (MLSS(wcont)); and (iii) 2 to 3 intermittent submaximal CWRT (7 × 4 min and 1 × 2 min, with 2-min recovery) with either passive or active recovery for the determination of MLSS(wint). MLSS(wint) was significantly higher when compared with MLSS(wcont) for both passive recovery (294.7 ± 32.2 vs. 258.7 ± 24.5 W, respectively) and active recovery groups (300.5 ± 23.9 vs. 273.2 ± 21.5 W, respectively). The percentage increments in MLSS(wint) were similar between conditions (passive = 13% vs. active = 10%). MLSS (mmol·L(-1)) was not significantly different between MLSS(wcont) and MLSS(wint) for either passive recovery (4.50 ± 2.10 vs. 5.61 ± 1.78, respectively) and active recovery (4.06 ± 1.49 vs. 4.91 ± 1.91, respectively) conditions. We can conclude that using a work/rest ratio of 2:1, MLSS(wint) was ∼10%-13% higher than MLSS(wcont), irrespective of the recovery type performed during prolonged intermittent exercises.
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