Author(s): TANAKA, S.1, ARAI, C.1, HATASHIMA, K.1, HIRATSUKA, K.2, KUMAGAWA, D.1, Institution: KOKUSHIKAN UNIVERSITY , Country: JAPAN, Abstract-ID: 1418

INTRODUCTION:
The Muscle Contraction Sensor (MC sensor) method has been used to evaluate the mechanical activity during muscle contraction. It has been reported that muscle tension in the biceps brachii muscle measured by the MC sensor was related to the elbow flexion muscle strength under the isometric contraction (2, 3). In addition, interaction activity of thigh extensor muscles during knee extension has also been evaluated with the MC sensor (4). However, mechanical activity of agonist and antagonist muscles during knee extension-flexion is not clear. Therefore, the purpose of this study was to investigate the relationship between isometric knee extension-flexion muscle strength and mechanical activity of agonist and antagonist muscles by MC sensor method.
METHODS:
Eleven males (age: 23.8±1.7yrs, height: 174.1±5.6cm, weight: 67.5±5.9kg) without disabilities to knee joint were participated in this study. The isometric knee extension torque at knee joint angle of 90 degrees and flexion torque at knee joint angle of 30 degrees were measured using a dynamometer (Biodex co.). At the same time, the muscle tension as an index of mechanical activity at rectus femoris (RF), vastus lateralis (VL), vastus medialis oblique (VMO), and biceps femoris long head (BF) were measured by Muscle Contraction Sensor (TMG-BMC) method. These measurement parameters were calculated the relative mean value based on each 5% per maximal knee extension-flexion torque in all subjects.
RESULTS:
The mechanical activity of RF, VL and VMO as the agonist muscles increased with increasing knee extensor muscle strength. Significant correlations were observed between the mechanical activity of the knee extensor muscles and extension muscle strength, respectively. In addition, a significant correlation was also observed BF for the antagonist muscle with knee extension muscle strength. Significant correlations were also obtained between mechanical activity of thigh muscles and flexion muscle strength. The correlation coefficients were 0.993 for the BF as the agonist muscle, and 0.988 for the RF, 0.994 for the VMO, and 0.965 for the VL as the antagonist muscles.
CONCLUSION:
The level of muscle strength is affected by the co-activity of the agonist and antagonist muscles (1). Therefore, it is important to maintain a balance between the activity of the agonist and antagonist muscles. In this study, it was cleared that the mechanical activity measured by the MC sensor could be an indicator to estimate the level of muscle strength not only in the agonist muscles but also in the antagonist muscles. From these results it was suggested that mechanical activity using the MC sensor method is useful for estimating muscle strength and evaluate the balance between the agonist and antagonist muscles.
REFERENCES:
1) Baratta et al., A. J. Sports Med, 1988
2) Srdjan et al., Sensor, 2011
3) Srdjan et al., Sensor, 2014
4) Tanaka et al., 28th ECSS, 2023