Purpose This study aimed to investigate the reliability of surface electromyography (EMG) assessed at seven muscles during three repeated 2000 m rowing ergometer sessions. Methods Twelve male well-trained rowers participated in a repeated measures design, performing three 2000 m rowing ergometer sessions interspersed by 3-7 days (S1, S2, S3). Surface electrodes were attached to the gastrocnemius, biceps femoris, gluteus maximus, erector spinae, vastus medialis, rectus abdominis and latissimus dorsi for EMG analysis. Results No differences existed between 2000 m sessions for EMG amplitude for any of the seven muscles (p = 0.146-0.979). Mean coefficient of variation of EMG for 6 of 7 muscles was `acceptable` (12.3-18.6%), although classed as `weak` for gastrocnemius (28.6%). Mean intra-class correlation coefficient values across muscles ranged from `moderate` to `very large` (0.31-0.89). Within-session EMG activation rates of vastus medialis were greater during 0-500 m and 1500-2000 m segments, compared with 500-1000 m and 1000-1500 m (p < 0.05). Values for biceps femoris and gluteus maximus were significantly higher during 1500-2000 m compared to 500-1000 m and 1000-1500 m (p < 0.05). The general pattern was for higher activation rates during 0-500 m and 1500-2000 m compared to 500-1000 m and 1000-1500 m. However, there were no between-sessions differences in EMG for any of the 500 m segments (p > 0.05). Conclusion Reliability of EMG values over repeated 2000 m sessions was generally `acceptable`. However, EMG was seemingly not sensitive enough to detect potential changes in neural activation between-sessions, with respect to changes in pacing strategy.
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