STUDY: Drinking cold liquids extends exercise capacity in MSers
Cold fluid ingestion extends exercise capacity of heat-sensitive individuals with Multiple Sclerosis in a warm environment
Georgia K Chaseling1,
Scott L Davis4 and
1University of Sydney, Sydney, Australia
2Neuroscience Research Australia, Randwick, Australia
3Sydney Medical School, Brain and Mind Centre, Sydney, Australia
4Department of Applied Physiology & Wellness, Southern Methodist University, Dallas, TX
Exposure to a hot environment or heat gained during exercise can elicit a transient worsening of clinical symptoms in person with multiple sclerosis (MS), a demyelinating disease of the central nervous system). Heat-related fatigue has been reported in 60–80% of individuals with MS, potentially limiting physical activity. Therefore, simple interventions that mitigate heat-related reductions in exercise capacity in persons with MS are needed. Our aim was to test the hypothesis that cold fluid ingestion prolongs exercise duration of individuals with relapsing-remitting MS cycling in a warm (30°C, 35% RH) environment.
On two randomized occasions, 7 participants (54 ± 7 y; 76.1 ± 10.9 kg; 1.71 ± 0.09 m) diagnosed with relapsing-remitting MS exercised at a low intensity (heat production: 3.2 ± 0.5 W·kg−1) for a maximum of 60 min (or until exhaustion), while ingesting a 3.2 mL·kg−1 aliquot every 15 min of either cold (1.5°C: CLD) or thermoneutral (37°C: NEU) water. Rectal (Tre) and mean skin (Tsk) temperature was continuously measured. Exercise duration was significantly longer (P=0.05) in the CLD trial (54.3 ± 11.0 min) compared to the NEU trial (46.4 ± 14.1 min). Indeed, after 45-min of exercise, 3 of 7 participants remained in NEU, whereas 6 of 7 participants remained in CLD. All subjects were able to complete a minimum of 31 minutes of exercise. At this time point, absolute Tre (CLD: 37.08 ± 0.34°C, NEU: 36.99 ± 0.26°C; P = 0.59), the change in Tre (CLD: 0.25 ± 0.30°C, NEU: 0.25 ± 0.15°C; P =0.99), absolute Tsk (CLD: 34.41 ± 0.45°C, NEU: 34.31 ± 0.30°C; P = 0.57), and the change in Tsk (CLD: 1.35 ± 0.54°C, NEU: 1.41 ± 0.53°C; P = 0.63) were all similar between CLD and NEU. Additionally, at the termination end-point of exercise, absolute Tre (CLD: 37.23 ± 0.30°C, NEU: 37.20 ± 0.26°C; P = 0.82), the change in Tre (CLD: 0.32 ± 0.30°C, NEU: 0.45 ± 0.18°C; P =0.70), absolute Tsk (CLD: 34.81 ± 0.27°C, NEU: 34.61 ± 0.35°C; P = 0.15), and the change in Tsk (CLD: 1.75 ± 0.85°C, NEU: 1.68 ± 0.88°C; P = 0.72) were all similar between CLD and NEU.
In conclusion, during physical activity in a warm environment, heat-sensitive individuals with MS exercised for longer before exhaustion with the ingestion of a cold compared to a thermoneutral fluid.