MODULATION OF PRESSURE PAIN THRESHOLDS DURING AND FOLLOWING ISOMETRICCONTRACTION

This study aimed at evaluating the influence of submaximal isometric c ontraction on pressure pain thresholds (PPTs) in 14 healthy volunteers before and after skin hypoesthesia. PPTs were determined with pressur e algometry over m. quadriceps femoris before, during, and following a n isometric contraction. Maximum voluntary contraction (MVC) was asses sed using a computerized dynamometer. A contraction of 21% MVC was hel d until exhaustion (max: 5 min) and PPTs were assessed every 30 sec. A local anesthetic cream and a control cream were applied following a d ouble-blind design and PPTs were reassessed. PPTs increased significan tly at the start of contraction and continued to increase until the mi ddle of the contraction period, then remaining at this level. After co ntraction PPTs decreased significantly but for 5 min remained slightly above precontraction levels. Anesthetic cream raised PPT at rest but not during and following contraction. The relative increase in PPTs du ring and immediately following isometric contraction was lower with an esthetic cream. Isometric contraction of m. quadriceps femoris increas e PPTs during and following contraction. The results suggest that inpu t from cutaneous and deeper tissues interacts with nociceptive activit y set up by the pressure stimulus. Determining the degree of sensory m odulation in muscle and skin in different chronic pain syndromes could become a functional method of patient assessment important for differ ential diagnosis, treatment evaluation, and follow-up.