Force, contraction frequency and energy metabolism as determinants of ischaemic muscle pain

Ischaemic muscle pain was studied in a total of 78 experiments on 3 normal subjects. The development of pain induced by intermittent voluntary isometric contractions was recorded whilst force and frequency of contraction were varied. As the muscle progressively expends energy, pain (P) develops in an exponential fashion and can be expressed by the function P = (F x t)k/C where (F x t) is the integral of force with time, k, an exponent, and C, a constant. The exponent is fairly constant despite changes in frequency. The time of pain onset and energy expenditure at the point of intolerable pain depend on frequency. At a given frequency, energy expenditure at intolerable pain is independent of the force of contraction.