Steady-state stress at one hand magnifies the amplitude, stiffness, and non-linearity of oscillatory behavior at the other hand.

ABSTRACT

Stress at one body segment can influence rhythmic movements of non-neighboring body segments. The nervous, circulatory, and fascia (connective tissue) systems are potential mediators of such remote effects. Assessing them begins with a detailed description of the remote effects. Precisely, how do the rhythmic movements change? In our experiment with seven participants, left-hand oscillations of held pendulums at self-selected frequencies were examined as a function of right-hand tonic forces of 0, 10 or 20% of the maximum voluntary contraction. We evaluated the effect of the right hand's tonic force on the amplitude and frequency, and the stiffness and friction functions of the left hand's oscillations. Our results suggest that (a) amplitude and stiffness (both linear and non-linear) increased with tonic force but frequency and friction (both linear and non-linear) did not, and (b) the stiffness increases due to right hand 10 and 20% stress were indifferent to the initial (0%) left-hand stiffness values. Discussion took note of how the nervous system and architectural features of the body (e.g., its network of connective tissue) may produce such effects.