Construction and Empirical Research on Relationship Model between Load and Muscle Activity under Stable and Unstable States

     To investigate the relationship between load and muscle activity.

  Methods:  The study designed an EMG test, i.e., 30 subjects were tested in deep squat with different loads under both stable (ground) and unsteady (balance Plate) states.

  Results:  (1) Load and muscle activity under different states were showed significantly positive correlation (steady state:r=0.700, P < 0.000;unsteady state:r=0.821, P < 0.000;whole state:r=0.773, P < 0.000).(2) A certain difference exists in the stimulus degree of the body muscle activity under stable and unstable states, but varies with the increase of load.(3) The linear model (adjusted R²=0.864~0.914) and the nonlinear model (adjusted R²=0.876~0.931) were both fitted well.

  Conclusion:  The relationship between load and muscle activity in both stable and unstable states may be in line with an "S" curve relationship model, and this model is affected by both the "characteristic forms" and the "biological" factors, and there is also the dominant factor transformation.The empirical study indicates that the "S" curve model can better compensate for the overestimation of the linear model.