Evaluation of muscle fatigue during 100-m front crawl

Abstract

The aim of this study was to evaluate muscle fatigue in upper body muscles during 100-m all-out front crawl. Surface electromyogram (EMG) was collected from the pectoralis major, latissimus dorsi and triceps brachii muscles of 11 experienced swimmers. Blood lactate concentration level increased to 14.1 ± 2.9 mmol l(-1) 5 min after the swim. The velocity, stroke length and stroke rate calculated based on video analysis decreased by 15.0, 5.8 and 7.4%, respectively, during the swim. EMG amplitude of the triceps and the lower part of the latissimus muscles increased, whilst the mean power frequency (MNF) of all muscles significantly decreased by 20-25%. No significant differences in the relative MNF decrease were observed amongst the muscles; however, the differences in the rate of the MNF decrease between the lower part of the latissimus and the triceps brachii muscles were found (P < 0.05). The time of rest between the muscle activation of the two consecutive arm strokes at the end of swimming was extended (P < 0.05). It was concluded that 100-m all-out crawl induced significant fatigue with no evident differences amongst the analysed muscles.

Observação e caracterização técnica em natação pura desportiva: 200 m bruços

“…The lactate concentrations obtained were similar to previous studies for 200 m distances 26,[45][46][47] , corroborating that the 200 m event presents significant anaerobic contribution. The decrease pre-sented in SV, SF and Sl agree with the results presented by previous studies 3,9,12,7,48 , when refer that in the breaststroke technique there is increase in SV associated with increase in SF, but higher decrease in Sl relatively to other swimming styles 9 , corroborating alteration in the technique during the 200 m 3 .…”

“…This amplitude increase was also demosntrated in other types of maximum protocols used in swimming, namely in the crawl stroke 26,28,30 . Many negative correlations were obtained between frequency and SV, SF and Sl; that is, for the BB, TB and pM muscles, strong correlation was verified among SV, SF and Sl, meaning that as the kinematic variables increase, the frequency decreases, while for the Ad muscle, the values are very close to zero in module, it is an indication that alterations in the kinematic variables do not reflect in the frequency of this muscle.…”

“…in the amplitude domain, many studies presented amplitude increase of the neuromuscular activity [27][28][29][30] . in the frequency domain, decrease in the neuromuscular activity was observed as presented by Stirn et al 26 in which 20-25% reduction of frequency and increase of amplitude of the triceps brachii and pectoralis major dorsal have occurred.…”

“…studies have been developed with the crawl stroke [22][23][24][25][26] , demonstrating hence a study gap in the breaststroke.…”

“…Bipolar surface electrodes (10 mm diameter, plux, lisbon, portugal) were used with distance between electrodes of 20 mm. The electrodes on the upper part of the pM were placed on the mean line which connects the acromion to the manubrium (externum), two fingers below the clavicle 26 . The electrodes on the long part of the TB, BB and Ad were laced according to the SEniAM recommendations 41 .…”