Twelve Weeks of Anti-Fatiguing Aerobic Exercise Leads to Increased Exercise Duration in Individuals with MS

Background: Aerobic exercise is typically recommended for MS patients. However, the amount of heat generated during this type of activity can be significant and result in the early onset of fatigue.

Objectives: The objective of this study was to determine the effects of 12 weeks of anti-fatiguing aerobic exercise during exercise performance with cooling vs. no cooling in MS patients.

Methods: Forty-five MS patients (79% female, 91% relapsing-remitting, age=50.1±8.3 yrs, EDSS=1.4±1.2, yrs since diagnosis=11.5±8.1) participated. Subjects were randomly assigned to one of three groups – exercise + cooling (E+C, n=12), exercise with no cooling (ENC, n=13), or control (C, n=19). Before and after the 12-week intervention, all subjects performed a maximal graded exercise test (GXT) in a 70°F room  and then, on another day, cycled at 60% of their individual maximal workload for as long as possible in an environmental chamber set at 80°F with 50% humidity. Core (Tc) and skin (Ts) temperatures, blood pressure and heart rate were measured continuously. During these tests, the subjects were not cooled. For those randomized to the 12 weeks of anti-fatiguing aerobic cycling, E+C wore a passive cooling vest during each training session, while ENC did not. C did not do any training. The intermittent cycling program (cycles of 2, 4 or 6 min of pedaling followed by 2 min of rest for 1 hour, 3x/wk) used progressive intensities of 40, 60, 80 and 100% of each person’s maximal workload over the 12 weeks. Perceived physical and cognitive fatigue were assessed during exercise and recovery using a 10 cm visual analog scale.

Results: Overall, the maximal exercise duration significantly increase by 41% for the exercisers (23.7±8.7 to 33.4±9.8 min) (p<.05) and decreased by 6% in C (23.5±12.0 to 22.1±15.0 min). Each exercise group had significant increases in duration, with ENC increasing by 57% (22.3±10.8 to 35.0±8.7 min) and E+C increasing by 29% (24.8±7.0 to 32.0±11.0 min) (p<.05). VO2max increased by 10% for ENC and 2% for E+C, but decreased by 3% for C. Maximal workload increased by 32% for ENC and 28% for E+C, but decreased by 5% in C. There was no change in perceived fatigue. Tc for the exercisers, on the post-test, did not increase proportionally to the increase in their work capacity.

Conclusions: Both exercise groups (ENC and E+C) achieved a higher work capacity, while Tc and perceived fatigue were the same after 12 weeks of anti-fatiguing aerobic exercise. ENC had better improvements than E+C, while C either stayed the same or declined. These data indicate an adaptation to exercise training and exercise in the heat.

This study was funded by NIDRR grant H133G050198.