Relationship between decreased swimming velocity and muscle activity during 200-m front crawl

Abstract

The aims of this study were (1) to evaluate changes in muscle activity associated with physiological fatigue and decreased swimming velocity (SV) during 200 m of front crawl swimming, and (2) to examine the relationship between the decreased SV and changes in kinematic or electromyogram parameters. Twenty swimmers participated in a 4 × 50-m swim test. The surface EMG of 11 muscles (7 in the upper limbs and 4 in the lower limbs) was measured and the mean amplitude value (MAV) for one stroke cycle was obtained. The SV and arm angular velocity (AAV) of shoulder flexion during the first (early stroke) and second (late stroke) half of the underwater arm stroke were analyzed using an underwater camera. The AAV, the MAV of flexor carpi ulnaris (FCU), biceps brachii (BB), and triceps brachii during the early stroke, and the MAV of rectus femoris decreased along with a decrease in SV. In contrast, the MAV of the pectoralis major (PM) increased significantly in the final 50 m. The rate of change in MAVs (ΔMAVs) of FCU, BB and latissimus dorsi during the early stroke, and ΔMAV of biceps femoris were significantly correlated with ΔSV and/or ΔAAV. Positive correlations were identified between ΔMAVs of several muscles. However, no negative correlations were observed between ΔMAVs. These results suggest that the decrease in SV was related to decreases in the activities of several muscles that coordinated with each other, and that a compensating strategy occurred between PM and other muscles in the final 50 m.

EMG frequency spectral characteristics of inspiratory accessory muscles during the shoulder lifting motion in throwing athletes

“…(24,25) We have not found studies in the literature that sought to observe the EMG frequency spectral characteristics (fatigue index) of inspiratory muscles in throwing athletes. Nevertheless, Stirn, (12) Ikuda (13) and Lomax (14) corroborated in part with our findings, since they saw the presence of fatigue through the EMG, the pectoralis major muscle, which carries double mechanical function during sporting gesture of swimmers, generated by high mechanical requirement for the gesture and simultaneous activation in the process of inspiration at high intensities of exercise. However, they did not assess the symmetry of the tested muscles, making it difficult to infer information of asymmetric responses in inspiratory fatigue of athletes evaluated.…”

“…(10) Recent studies have investigated, through the EMG, the fatigue index of upper limb muscles performing dual mechanical function during the sporting gesture, as the pectoralis major muscle, in which muscle fatigue was observed with reduction of EMG median frequency after maximum activities sports. (11)(12)(13)(14) However, we found no studies that verify the fatigue of inspiratory muscles compared to the shoulder lifting movement in throwing athletes. One study found the sternocleidomastoid (SCM) muscle behavior against the lifting of the arms, for ergonomic analysis, showing the occurrence of co-activation of this muscle against the motion.…”

Recent Observations in Surface Electromyography Recording of Triceps Brachii Muscle in Patients and Athletes

“…The studies on rehabilitation utilised sEMG electrodes to measure the TB activity of patients of stroke [21][22][23][24], spinal cord injury [25][26][27][28], cerebral palsy [29], gait disorder [8,30], fatigue injury [20,31], and joint stability injury [17] during their trials. In contrast, the sports-based studies applied sEMG electrodes to measure the TB activity of athletes during the following sports activities: tennis [32][33][34], karate [35,36], pole vaulting [37], swimming [38,39], and dart throwing [40]. In addition, the sEMG activities of the TB were compared between healthy subjects and patients [21,22,24,28].…”

“…During the following movement: reaching out from a starting position, picking up a cylinder, and returning it to the starting position Seventeen of the studies used bipolar or triode silver/silver chloride (Ag/AgCl) sEMG electrodes, one study [39] utilised bipolar gold sEMG electrodes, and one study [29] applied polycarbonate sEMG electrodes for the recording of the EMG activity on the TB. In addition, one study used a linear array of four silver bar sEMG electrodes [32].…”

“…Of the 23 selected studies, eighteen recorded the heads of the TB, whereas the four studies [8,17,32,39] focused the muscle belly of TB, and one study [22] did not mention the specific anatomical location on the TB used for the sEMG recordings. Of the 18 studies that analysed the TB heads, 12 studies [21, 23-25, 27, 29, 31, 33-37] focused on the lateral head, 11 studies [21, 24-26, 28, 30, 33-35, 38, 40] analysed the long head, and three studies [20,24,31] focused on the medial head.…”