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Force development of dynamic and static contractions in children and adults
Insights
Children exhibit slower muscle force development and longer contraction delays compared to adults. These differences in muscle function are evident in both dynamic and static contractions, impacting overall physical capabilities.
Area of Science:
- Pediatric Exercise Science
- Human Muscle Physiology
- Biomechanics
Background:
- Limited understanding of force development characteristics in children with immature motor skills.
- Known morphological, histological, and biochemical differences exist between immature and mature muscles.
Purpose of the Study:
- To examine and compare force development characteristics during dynamic and static elbow flexion contractions in six-year-old children and adults.
- To investigate differences in force-velocity relationships, force-time relationships, and electromyography (EMG) patterns between the two age groups.
Main Methods:
- Evaluated dynamic elbow flexion using varying loads to determine force-velocity relationships.
- Assessed static contractions of elbow flexors at maximum effort, analyzing force-time relationships and electromyograms (EMG).
- Compared maximum power output, contraction delay, and electromechanical delay between children and adults.
Main Results:
- Children demonstrated significantly lower maximum power output (22.8 W) compared to adults (160.8 W).
- Greater contraction delay and electromechanical delay were observed in children across all relative loads.
- Children exhibited lower contractile speed in both dynamic and static contractions compared to adults.
Conclusions:
- Six-year-old children display distinct differences in muscle force development compared to adults, characterized by slower contractile speeds and prolonged delays.
- These findings highlight age-related disparities in neuromuscular function that influence the capacity for rapid and forceful muscle contractions in developing individuals.
Abstract:
There are still unclarified points remaining in regard to the characteristics of force development in children who are immature in their basic activities in daily living. Moreover, there are morphological, histological, and biochemical differences between immature and mature muscles. In the present study, dynamic elbow flexion and static contractions which were performed by elbow flexors with maximum effort were examined by force-velocity and force-time relationships and electromyograms (EMG) in six-year-old children and in adults. In dynamic contractions with various loads, the force-velocity relationship for children was (P + 5.65) (v + 1.48) = 19.51, and (P + 14.65) (v + 2.26) = 96.21 for adults. The maximum power in children and adults was 22.8 watts and 160.8 watts, respectively. The contraction delay in children was greater than that in adults for every relative load. In static contractions, the maximum rate of force development for children was significantly lower than that for adults at each pre-tension. With an increase in pre-tension, the adult rate showed a tendency to decrease, whereas the rate for children showed no change. The electromechanical delay observed in children was significantly greater than that in adults. For dynamic and static contractions, the contractile speed in children was lower than that in adults.