Racing an Opponent Alters Pacing, Performance and Muscle Force Decline, But Not RPE.

Performing against a virtual opponent has been shown to invite a change in pacing and improve time trial (TT) performance. This study explored how this performance improvement is established by assessing changes in pacing, neuromuscular function and perceived exertion.After a peak power output test and a familiarization TT, twelve trained cyclists completed two 4-km TTs in randomized order on a Velotron cycle ergometer. Time trial conditions were riding alone (NO), and riding against a virtual opponent (OP). Knee-extensor performance was quantified before and directly after the TT using maximal voluntary contraction force (MVC), voluntary activation (VA) and potentiated doublet-twitch force (PT). Differences between the experimental conditions were examined using Repeated-measures ANOVAs. Linear regression analyses were conducted to associate changes in pacing to changes in MVC, VA and PT.OP was completed faster than NO (mean power output OP: 289.6±56.1W vs. NO: 272.2±61.6W; p=0.020), mainly due to a faster initial pace. This was accompanied by a greater decline in MVC (MVCpre-vs-post: -17.5±12.4% vs. -11.4±10.9%, P=0.032) and PT (PTpre-vs-post: -23.1±14.0% vs. -16.2±11.4%, P=0.041) after OP compared to NO. No difference between conditions was found for VA (VApre-vs-post: -4.9±6.7% vs. -3.4±5.0%, P=0.274). RPE did not differ between OP and NO.The improved performance when racing against a virtual opponent was associated with a greater decline in voluntary and evoked muscle force compared to riding alone, without a change in perceived exertion, highlighting the importance of human-environment interactions in addition to one's internal state for pacing regulation and performance.