The microcapillary infusion method was evaluated in recording intramuscular pressure during isometric and concentric exercise of the erector spinae muscle. Intramuscular pressure at rest was 6.1 (SD=1.4) mm Hg without infusion and 8.3 with an infusion rate of 1.5 ml/hour. When the subject experienced muscle fatique during exercise, the muscle relaxation pressure had increased to 14 mm Hg. The erector spinae muscle was found to be heavily loaded during exercise with an average muscle contraction pressure of 175 mm Hg. Recording of intramuscular pressure in the erector spinae muscle during exercise tests can be an additional method in the study of ergonomics and biomechanics of the spine as well as in the diagnosis of chronic compartment syndrome in this muscle.