Cold Water Ingestion Improves Exercise Tolerance of Heat-Sensitive People with MS

2018 Medicine & Science in Sports & Exercise  
1 Purpose: Heat intolerance commonly affects the exercise capacity of people with multiple 2 sclerosis (MS) during bouts of hot weather. Cold-water ingestion is a simple cooling 3 strategy but its efficacy for prolonging exercise capacity with MS remains undetermined. 4 We sought to identify whether cold-water ingestion blunts exercise-induced rises in body 5 temperature and improves exercise tolerance in heat-sensitive individuals with MS. 6 Methods: On two separate occasions, 20 participants
more » ... s, 20 participants (10 relapsing-remitting MS (EDSS: 1-7 5); 10 age-and fitness-matched healthy controls (CON)) cycled at 40% VO2max at 30°C, 8 30%RH until volitional exhaustion (or a maximum of 60 min). Every 15 minutes, 9 participants ingested 3.2 mL·kg -1 of either 1.5°C (CLD) or 37°C (NEU) water. Rectal (Tre) 10 temperature, mean skin (Tsk) temperature, and heart rate (HR) were measured throughout. 11 Results: All 10 CON, but only 3 of 10 MS participants completed 60 minutes of exercise in 12 NEU trial. The remaining 7 MS participants all cycled longer (P=0.006) in CLD 13 (46.4±14.2 min) compared to NEU (32.7±11.5 min), despite similar elevations in absolute 14 Tre (NEU: 37.32±0.34˚C; CLD: 37.28±0.26˚C; P=0.44), change in Tre (NEU: 0.38±0.21˚C; 15 CLD: 0.34±0.24˚C), absolute Tsk (NEU: 34.48±0.47˚C; CLD: 34.44±0.54˚C; P=0.82) and 16 HR (NEU: 114±20 b•pm -1 ; CLD: 113±18 b•pm -1 ; P=0.38) for the same exercise volume. 17 Conclusions: Cold-water ingestion enhanced exercise tolerance of MS participants in the 18 heat by ~30% despite no differences in core and mean skin temperatures or heart rate. 19 These findings support the use of a simple cooling strategy for mitigating heat intolerance 20 with MS, and lend insight into the potential role of cold-afferent thermoreceptors that 21 reside in the abdomen and oral cavity in the modulation of exercise tolerance with MS in 22 the heat. 23 3
doi:10.1249/mss.0000000000001496 pmid:29140896 fatcat:7hgq7xaxazftfdcwya5u7zr3mq