Examining EMG activity of the elbow flexors and extensors muscles during maximal arm cycling sprints in pronated and supinated forearm positions

Barzegar Ganji, Zahra (2022) Examining EMG activity of the elbow flexors and extensors muscles during maximal arm cycling sprints in pronated and supinated forearm positions. Masters thesis, Memorial University of Newfoundland.

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Abstract

Sprinting exercise is near maximal or maximal bouts of exercise interspersed with short recovery intervals. Sprinting exercise causes deterioration in performance (e.g., a decline in power output or velocity) due to a decrease in force and the development of neuromuscular fatigue (NMF). Studies have used sprinting exercises to study the interaction between fatigue and performance and have shown that NMF development could differ due to the specific task. For example, NMF development could occur during maximal running and leg cycling exercises at the same workload. This suggests that NMF appears to develop differently depending on the specific action of the muscles involved. To date, only one study has investigated the NMF in arm cycling in pronated versus supinated positions. This study indicated that supinated arm cycling sprints resulted in worse repeated sprint performance and greater NMF than pronated RSE. In sprint-like activities, a common way to quantify the development of NMF is to normalize the EMG of each sprint to the maximum EMG observed during the sprinting or to normalize EMG to the EMG recorded during a maximum voluntary contraction. However, to date, normalization processes for EMG during maximal effort sprinting activities are inconclusive across studies. Moreover, no research has applied the complete recorded EMG signals to interpret muscle activity throughout maximal arm cycling sprint. Therefore, this study aimed to use different EMG normalization methods to elbow flexors and extensors in supinated and pronated positions of arm cycling to examine which method shows better changes in NMF and forearm position. Statistical parametric mapping (SPM) Repeated measure (RM) ANOVA showed significant decreases (p<0.05) in muscle EMG activity of biceps brachii and brachioradialis from sprint 1 to 10 in all normalization methods, as well as a significant (p<0.05) decline in triceps brachii EMG activity in maximum sprint normalization method. Moreover, SPM paired t-tests showed that MVC normalization detected the changes between pronated and supinated positions of biceps brachii and triceps brachii. This study improves our understanding of the best methods of EMG normalization to interpret muscle EMG activity in research and clinical EMG application.

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