Heat Regulation Dysfunction May Stop MS Patients from Exercising

Released: 24-Apr-2014 11:00 AM EDT
Embargo expired: 29-Apr-2014 3:45 PM EDT
Source Newsroom: Federation of American Societies for Experimental Biology (FASEB)
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Citations Experimental Biology, April-2014

Newswise — San Diego, CA (April 29, 2014) — Exercise can be beneficial for patients with multiple sclerosis, a degenerative nerve disease that progressively impairs central nervous system function. However, for some patients, a rise in body temperature, which occurs during exercise and/or exposure to hot and humid conditions, can make symptoms temporarily worse. Researchers at Southern Methodist University collaborating with colleagues from University of Sydney set out to explore how moderate exercise affected patients with MS compared with healthy control subjects. Mu Huang, will present the research team’s findings in a poster session on Tuesday, April 29, at the Experimental Biology meeting (San Diego Convention Center from 12:45–3:00 PM PDT).

Huang et al. asked five patients with MS and five control subjects to cycle in a temperature-controlled room for 30–60 minutes. They found that sweating took longer to start and sweat rate was lower during exercise-induced body temperature increases in MS patients compared to healthy control subjects. This altered temperature regulation also led to a greater increase in core temperature among the MS patients vs. controls. Overheating in this way could cause a temporary worsening of symptoms, which may impact the ability to exercise or discourage patients with MS from exercising.

From the researchers: “While preliminary, these findings suggest that a larger rise in body temperature seen in MS patients is due to a lower sweat rate and a delay in the start of sweating thereby limiting the body’s ability to cool itself down. A greater understanding of how MS affects the body’s ability to dissipate heat during exercise will provide insight into ways of reducing the impact of heat intolerance and improving the safety and benefit of exercise for MS patients.”

Full Abstract
Thermoregulatory dysfunction in multiple sclerosis patients during moderate exercise in a thermoneutral environment

Impairments in sudomotor function during passive heat stress have been reported in multiple sclerosis (MS), a demyelinating disease of the CNS that disrupts autonomic function. However, little is known regarding exercise induced increases in core body temperature on thermoregulatory mechanisms in MS. Thus, the aim of this study was to test the hypothesis that thermoregulatory function is impaired in MS patients compared to healthy controls (CN) during moderate exercise. Thermoregulatory function in five patients diagnosed with relapsing-remitting MS and five mass-matched healthy controls were compared during a single bout of cycling exercise (fixed workload of 70 Watts) for 30-60 minutes in a climate-controlled room (25°C, 30% RH). Sweating thermosensitivity (MS: 0.56±0.15 vs CN: 0.81±0.13, p=0.04) was significantly lower while a delay in sweating onset time (MS: 14.8±10.0 min vs CN: 5.6±1.6 min, p=0.07) approached significance in MS patients compared to controls. These altered mechanisms of body temperature regulation likely contributed to a greater observed change in core body temperature measured rectally (MS: 0.84±0.34 °C vs CN: 0.37±0.27 °C, p=0.04) in patients with MS. This observed thermoregulatory dysfunction in MS patients may intensify disease symptoms limiting exercise tolerance.

NOTE TO JOURNALISTS: To schedule an interview with a member of the research team, please contact Stacy Brooks at sbrooks@the-aps.org or (240) 432-9697.

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