Neuromuscular Fatigue During a Simulated Sprint Triathlon Is Independent of Performance Level.

PURPOSE: To investigate the influence of trained triathletes' performance levels on neuromuscular fatigue development during a sprint triathlon. METHODS: Nineteen male trained level triathletes performed a sprint triathlon simulation and were separated into "higher performance experience volume" (n = 11) and "lower performance experience volume" (n = 8) based on overall sprint triathlon race time, triathlon experience, and weekly training volume. Neuromuscular, central, and peripheral fatigue were evaluated from changes in force (maximal voluntary isometric contraction), voluntary activation level, and twitch responses of the quadriceps muscle (Qtw,pot), respectively. RESULTS: Swimming speed relative to critical speed, cycling power relative to cycling respiratory compensation point, and running speed relative to running respiratory compensation point were similar between groups (P ≥ .24). Significant main effects of time were observed for maximal voluntary isometric contraction, voluntary activation level, and Qtw,pot (P < .001), with no group or group × time effects (P > .14). Qtw,pot was lower at postswimming compared to baseline (P < .001) and further decreased postcycling (P < .001). Following the running phase, Qtw,pot partially recovered to values comparable to postswimming (P > .57), was greater than postcycling (P < .006), but remained below baseline (P < .001). This time-course was similar between lower performance experience volume and higher performance experience volume athletes. CONCLUSION: The trained athletes of higher performance experience volume and lower performance experience volume groups set the intensity of each discipline at similar threshold percentages, leading to similar levels of neuromuscular, central, and peripheral fatigue after each discipline of a sprint triathlon.