Κυριακή, 27 Ιανουαρίου 2019

Changes in blood lactate and muscle activation in elite rock climbers during a 15-m speed climb

Abstract

Purpose

The purpose of this study was to investigate the changes in blood lactate concentration (BL) and muscle activity patterns during a 15-m speed climbing competition that consisted of ten consecutive climbing actions on a standardized artificial wall in trained rock climbers.

Methods

Twelve trained rock climbers participated in this study. Surface electromyography (sEMG) and video signals were synchronized and recorded during climbing. The blood lactate was also tested 3 min after completing the climb.

Results

The average climbing time was 8.1 ± 2.1 s for the 15-m speed climb across all subjects, accompanied by a BL of 7.6 ± 1.9 mmol/L. The climbing speed and power firstly increased and then slightly decreased relative to peak value during the 15-m speed climbing. The results showed there was a positive correlation between the BL and the climbing time, r = 0.59, P = 0.043. The sEMG showed the flexor digitorum superficialis (FDS) electric activity was the highest, followed by the biceps brachii (BB) and latissimus dorsi. The instantaneous median frequency of sEMG of FDS and BB significantly decreased during the 15-m speed climbing. All the participants showed the higher sEMG RMS (%) in the terminal phase than that in the initial phase, especially with a greater increase in the left upper limbs. However, the lower limbs muscles presented no significant changes in the sEMG amplitude during climbing.

Conclusions

The FDS and BB play an important role in completing the 15-m speed climbing. The median frequency of arm EMG decreased more than that of legs, suggesting more fatigue. The blood lactate concentration increases in the current study suggest that a certain amount of glycolysis supplies energy in completing 15-m speed rock climbing. Based on the current data, it is suggested that muscular endurance of FDS and BB muscles in upper limbs should be improved for our climbers in this study.



from Physiology via xlomafota13 on Inoreader http://bit.ly/2WnqPRi
via IFTTT

Associations between sensorimotor gating mechanisms and athletic performance in a variety of physical conditioning tests

Abstract

Purpose

The elite athlete is fine-tuned all around to deliver favorable results in sporting events. In this study, we address the question of whether basic movements—such as reflexes—and heterogeneous attentional modulation components—such as sensorimotor gating mechanisms—are also tuned up to maximize the results of middle-distance runners in physical conditioning tests.

Methods

We selected an array of professional middle-distance runners and healthy counterparts that were submitted to measurement of (1) physical conditioning parameters, including somatotype, jump, strength, and flexibility tests; and (2) sensorimotor gating mechanisms, including acoustic startle reflex, prepulse inhibition, and habituation.

Results

Our results showed athletes scored better on the athletic tests compared to controls, as expected. They also exhibited a lower startle amplitude, while maintaining higher prepulse inhibition values. They reacted faster to the acoustic stimuli, and sex-related differences—found in controls—were not present in athletes. Our data also pointed out to substantial correlations between sensorimotor gating and physical conditioning parameters.

Conclusions

All in all, these data may point to physical conditioning-driven neural plasticity of brain sensorimotor gating circuits in charge of triggering involuntary movements to harness control and efficiency over reflexed muscle activity.



from Physiology via xlomafota13 on Inoreader http://bit.ly/2B6x42K
via IFTTT