1
Student (Ph. D) Faculty member shomal University*
2
M.A Pathology Sport
3
M.A Faculty member Noshahr Azad Islamic University
Abstract
Muscle fatigue has been defined as an acute, exercise-induced reduction in the maximum force-generatin capacity of a muscle. When muscle contraction with low force production is sustained for a long time, the individual synergistic muscles are not continuously activated but alternate between periods of activity and silence. The purpose of this study was to investigate the functional interrelationship between synergistic muscle activities during a sustained sub maximal isometric plantar flexion. In a expremental design, 12 healthy male subjects with no history of lower limb injury have been volunteered for this study. Subjects performed 50 repetition of calf raise and sustained isometric calf raise task for 60 sec immediately. Surface electromyogram recorded from lateral gastrocnemius (LG), and medial gastrocnemius (MG) during isometric contraction. The data were divided into 10-sec blocks. Alternate muscle activity between two muscles was assessed by repited masure ANOVA analysis on the basis of the LG/MG rate of integrated EMG (IEMG). In addition Pearson Correlation coefficients were computed between IEMG values recorded from MG and LG to investigate between-synergist substitution. The result indicated that there is a significant difference (p≤0.05) in LG/MG IEMG’s ratio among 6 blocks (10 sec) during 1 min isometric contraction, suggesting that these muscles generally didn’t acted together. There was a moderately strong negative correlation, but not significant (p>0.05), in IEMG between LG and MG during contraction, demonstrated a tendency toward trade-off synergism. The findings of this study suggest that the relative activation of medial and lateral gastrocnemius are not constant during submaximal fatiguing task and these synergists most likely rotate in a complementary pattern to maintain the constant force
Afshar Nejad, T., KHorsandi, M., & Tari, M. (2012). Alternate activity of medial and lateral gastrocnemius muscles during a sustained sub maximal isometric plantar flexion. Contemporary Studies On Sport Management, 2(3), 19-32.
MLA
Taher Afshar Nejad; Masoud KHorsandi; Mohsen Tari. "Alternate activity of medial and lateral gastrocnemius muscles during a sustained sub maximal isometric plantar flexion". Contemporary Studies On Sport Management, 2, 3, 2012, 19-32.
HARVARD
Afshar Nejad, T., KHorsandi, M., Tari, M. (2012). 'Alternate activity of medial and lateral gastrocnemius muscles during a sustained sub maximal isometric plantar flexion', Contemporary Studies On Sport Management, 2(3), pp. 19-32.
VANCOUVER
Afshar Nejad, T., KHorsandi, M., Tari, M. Alternate activity of medial and lateral gastrocnemius muscles during a sustained sub maximal isometric plantar flexion. Contemporary Studies On Sport Management, 2012; 2(3): 19-32.
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