Head–neck Cooling Effects on Central and Peripheral Fatigue, Motor Accuracy, and Blood Markers of Stress in Men with Multiple Sclerosis and Healthy Men: a Randomized Crossover Study

Background: The present study aimed to investigate whether head and neck cooling (at 18 degrees C next to the skin) and fatiguing submaximal exercise at a thermoneutral ambient temperature can induce peripheral and central responses in healthy men and those with multiple sclerosis (MS). Methods: A local head-neck cooling (at 18 degrees C next to the skin) intervention in men with a relapsing-remitting form of MS (n = 18; age 30.9 +/- 8.1 years) and healthy men (n = 22; age 26.7 +/- 5.9 years) was assessed. Men in both groups performed 100 intermittent isometric knee extensions with 5 s contractions and 20 s of rest. The primary variables were measured before exercise, after 50 and 100 repetitions, and 1 h after recovery. The central activation ratio, maximal voluntary contraction, electrically induced force, electromyography, contractile properties, blood markers, muscle temperature, and perception of effort were measured. Results: Compared with noncooled conditions, head and neck cooling increased the central capacity to activate exercising muscles but resulted in greater exercise-induced peripheral fatigue in men with MS (p < 0.05). Local cooling did not affect motor accuracy or the amplitude of electromyography signals; however, these factors were related to the intensity of the motor task (p > 0.05). The changes in central and peripheral fatigability induced by local cooling during submaximal exercise were more pronounced in men with MS than in healthy men (p < 0.05). Conclusion: Head and neck cooling enhances central activation of muscles during exercise, leading to improved exercise performance compared with noncooled conditions in men with MS.