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Purpose: To investigate the effects of feedback, in the form of a virtual avatar paced at 100% and 102% of baseline performance, on neuromuscular fatigue after a 4-km cycling time trial (TT). We hypothesized that improved cycling performance would occur because of the participants exceeding a previously established critical threshold and experiencing greater neuromuscular fatigue.

Methods: After familiarization, 10 well-trained cyclists performed a baseline 4-km TT without feedback (BASE), followed by two 4-km TT where they raced against an avatar (set at 100% accurate [ACC] and 102% deception [DEC] of baseline power output) in a randomized and counterbalanced order. Before and after each TT, neuromuscular fatigue was assessed using maximal isometric voluntary contractions (MVC) of the quadriceps, and supramaximal electrical stimulation of the femoral nerve, during and 2 s after MVCs to assess voluntary activation and potentiated twitch force. Blood lactate was taken pretrials and posttrials and RPE was taken throughout each TT.

Results: Time trial performance improved after deception of feedback compared with baseline performance (-5.8 s, P = 0.019). Blood lactate increased after DEC compared with BASE ( 1.37 mmol[middle dot]L-1, P = 0.019). Despite this, there was no difference in any measures of exercise-induced neuromuscular fatigue (P > 0.05). Similarly, RPE was not different between trials.

Conclusions: Well-trained male cyclists can improve cycling TT performance when competing against an avatar increased to 102% of a previously established best effort. However, this improvement is not associated with a measurable augmentation of neuromuscular fatigue.

(C) 2018 American College of Sports Medicine