Entropy-Based Analysis of Rowing Technique: Stroke-Rate Effects and Performance Implications

PURPOSE: The study aimed to (1) investigate the influence of different stroke rates on movement variability (MV), defined as normal variations in repeated motions, and (2) explore the relationship between MV and rowing performance. METHODS: Twenty-one elite male rowers (24.3 [3.1] y, 192.6 [5.6] cm, 90.7 [11.5] kg) performed 90-second submaximal intensity rowing bouts at 20, 26, and 34 strokes per minute (spm) on a static ergometer. Acceleration and joint angles collected from inertial sensors were used to measure MV through Sample Entropy. A 2000-m time trial was conducted to assess rowing performance. RESULTS: Stroke rate significantly increased the SD of stroke power (P = .001, ηp2=.198) and Sample Entropy value of handle acceleration (P < .001, ηp2=.407), hip (P < .001, ηp2=.733), knee (P < .001, ηp2=.806), ankle (P < .001, ηp2=.716), and elbow (P < .001, ηp2=.759) joint angles. Across all stroke rates, the hip consistently exhibited higher Sample Entropy than knee, ankle, and elbow. Greater variability in handle acceleration at 20 spm (r = -.626, P = .002) and 26 spm (r = -.581, P = .006), knee angle at 20 spm (r = -.531, P = .013), and elbow angle at 20 spm (r = .511, P = .021) correlated with better ergometer performance. CONCLUSIONS: Stroke rate plays a key role in modulating MV and technique in elite rowers, with higher stroke rate requiring more movement adaptation to maintain stroke power. Entropy measures may serve as a valuable tool for practitioners to assess and optimize rowing performance.