| Comparison of Muscle Force and Activation for Unilateral and Bilateral Movements in Multi-joint Leg Extension |
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Yong-Woon Kim, Sung-Tae Park |
Kyungnam University
Gyeongju University |
Correspondence:
Sung-Tae Park,
Email: whiteagr@hanmail.net
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Received: 13 November 2013 • Accepted: 18 January 2014 |
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| Abstract |
INTRODUCTION
This study aimed to identify the effects of movement patterns (unilateral [ULM] and bilateral movements [BLM]) on muscle force and muscle activation during multi-joint leg extension at various speeds under isometric and isokinetic conditions.
METHOD
A leg press, which facilitates extensions of the hip, knee, and ankle joint, was performed by 15 men in the age group of 20-29 under four speed conditions (0cm/s, 25cm/s, 50cm/s, 75cm/s) and two types of movements (ULM and BLM). The extension force and muscle activation were compared and the relationship between the force asymmetry in the left and right sides and the bilateral index was analyzed.
RESULT
In BLM, the extension force was decreased significantly compared to ULM, and the bilateral deficit was increased as the movement speed increased. Muscle activations of the rectus femoris and biceps femoris were decreased significantly during BLM and indicating that muscle activation is the main cause of reduction in the extension force. Although 7?14% asymmetry between the left and right forces was identified during ULM and BLM, there were no significant differences between the two movements. In addition, there was no significant correlation between the asymmetry in ULM and the bilateral deficit.
CONCLUSION
In multi-joint movements, which constitute most human motions, bilateral movement was confirmed as a performance-limiting factor that reduced mechanical output. In future studies, training methods for overcoming bilateral deficit during multi-joint movements were needed to be developed. |
| Keywords:
bilateral movement, unilateral movement, bilateral deficit, isokinetic exercise, asymmetry, leg extension |
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