| Summary: | This study aimed to investigate the changes
in surface electromyography (EMG) in four anatomical segments of three muscles
during a 2000 m rowing ergometer test. 19 healthy male rowers were
requested to perform the test. Surface electrodes were attached to their vast
medialis (VAM), erector spinae (ERS) and latissimus dorsi (LD) muscles. Raw EMG
signals were presented at five different distance points: start
(D0), 500 m (D1), 1000 m (D2), 1500 m (D3) and 2000 m (D4). The mean
velocity and power were greater during 0–500 m and 1500–2000 m phases compared
to 500–1000 m and 1000–1500 m phases (p < 0.01). Integrated
Electromyography (iEMG) of VAM was significantly higher at the start and 2000 m
compared to consecutive points (p < 0.05). The peak root mean square
(pRMS) of ERS muscles was significantly higher at the start and 2000 m
(p < 0.05). The frequency domain indexes mean frequency (MNF) and
median frequency (MDF) of all muscles were significantly reduced at 1500 m
compared to 1000 m (p < 0.05). However, no significant
changes were observed in time domain indexes of LD muscles at any distance points
(p > 0.05). A “fast start-speed maintains-final sprint” pacing
pattern was observed during the 2000 m all-out rowing ergometer test. The EMG
activation rates of VAM and ERS muscles were greater at the start and final
phases, contributing to the increase in power. The decline in MNF and MDF of all
three muscles at 1500 m could be related to greater muscle fatigue at this point.
When using EMG to analyze endurance exercise, the results were dependent on the
length of the test. Although not all EMG indexes were sensitive enough to detect
these changes, combing them with different indicators for a comprehensive
analysis might be considered.
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