Impact of music on running fatigue: Distraction effect from lyrics could further delay running fatigue compared to synchronous effect from tempo

Motivational music has been shown to improve running performance through delaying fatigue and increasing run duration. Previous studies have highlighted the effect of music tempo, that matching tempo to the runners cadence delays running fatigue. It remains unclear whether the motivational content in music lyrics is also responsible for delaying running fatigue. We designed a cross-sectional study and investigated the effect of tempo and motivational content on running biomechanics, and had participants run at a moderate intensity for up to ten minutes, or until exhaustion. Fifteen adults (age=20.9{+/-}1.3 years, weight=71.2{+/-}12.1 kg, height=174.7{+/-}11.0 cm) participated. Participants finished three trials, starting with running without any stimulus as a baseline trial, and ran with a visual metronome that flashed at a rate that matched their running cadence in the visual stimulus trial (VST). In the visual-auditory stimulus trial (VAST), participants ran with the visual metronome (as described in VST) while listening to a non-rhythmic motivational speech. We recorded run duration, perceived exertion, center of pressure sway during standing before and after each trial, and measured trunk acceleration to obtain root-mean-square (RMS) of acceleration during each minute of the run. Compared to baseline, participants reduced perceived exertion by 0.87 and 0.85 rating during the VST and VAST, respectively, though these changes did not reach significance (p=0.05). Stimulus affected the RMS of acceleration in anterior-posterior (p=0.011), vertical (p=0.008), and resultant directions (p=0.006). Our linear mixed effect model suggested that compared VST, VAST further lowered RMS of acceleration by 0.026g (anterior-posterior), 0.028g (vertical), and 0.036g (resultant). Our results showed that motivational content played an important role in lowering RMS of trunk acceleration, with the potential to delay running-induced fatigue. To maximize the effect of music on running performance, runners should listen to music that they find motivational and that is close to their natural running cadence.