Differences in Fatigue During Maximal Arm-Cycling Sprints Interspersed with 30s and 180s of Rest: 2555 Board #78 June 3, 9: 30 AM - 11: 00 AM.

PURPOSE: To investigate: 1) the time course of upper body fatigue during 10, 10s maximal arm-cycling sprints and 2) whether or not the extent of fatigue was dependent of the rest duration between sprints. METHODS: On two separate days, participants (N = 10) completed 10 trials of 10s maximal arm-cycling sprints interspersed with either 30s or 180s of recovery. Each session was separated by 48 hours. Peak power was recorded during all sprints. Participants performed a maximum voluntary contraction (MVC) of the elbow flexors prior to the first sprint and immediately post-sprints 5 and 10. Heart rate and rate of perceived exertion (RPE) were also recorded. RESULTS: Peak power decreased from sprint 1 to 10 by 35.8% (p < 0.001) and 11.5% (p = 0.010) when the sprints were interspersed with 30s and 180s rest, respectively. With the exception of sprint 1, participants produced a higher peak power from sprints 2-10 when the sprints were interspersed with 180s rest compared to 30s rest (p < 0.050). When the sprints were interspersed with 30s and 180s rest, MVC force decreased by 6.1% (p = 0.008) and 11.1% (p = 0.005) from pre-sprint 1 to post-sprint 5, 11.2% (p < 0.001) and 17.5% (p < 0.001) from pre-sprint 1 to post-sprint 10, and 5.1% (p = 0.039) and 6.4% (p = 0.014) from pre-sprint 5 to post-sprint 10, respectively. When the sprints were interspersed with 30s compared to 180s rest MVC force was 5.1% (p = 0.024) and 6.4% (p = 0.004) higher at post-sprints 5 and 10, respectively. From sprint 2-10, heart rate recovery was greater during 180s compared to 30s (p < 0.001). RPE increased throughout the sprints (p < 0.01) when sprints were interspersed with 30s and 180s rest, but no between-group differences occurred. CONCLUSIONS: Independent of rest time between sprints; there was a decrease in peak power during the sprints and elbow flexor MVC force. Interestingly, there was a greater reduction in MVC force of the elbow flexors when the sprints were interspersed with 180s compared to 30s of rest, which was opposite to the changes found for the power outputs (i.e. greater reduction in power when sprints were interspersed with 30s rest). Finally, changes in RPE were independent of rest time between sprints despite participants having higher heart rates and less heart rate recovery when performing sprints interspersed with 30s rest.