As many of you know, individuals with Multiple Sclerosis struggle with the heat, especially in Texas! A rise in core body temperature of less than one degree (0.36 – 0.9ºF) can cause heat intolerance for people with MS which causes rapid fatigue and exhaustion. In their ACSM study, Dr. Ollie Jay & Georgia Chaseling from the Thermal Ergonomics Lab at the University of Sydney, Australia investigated the role of heat perception on heat intolerance for people with MS. Their method was simple but significant: drinking cold water versus drinking room temperature water during exercise.
The study included 20 participants (10 MS, 10 non-MS matched by fitness level). On two separate trials, all participants did one hour of low intensity cycling on a recumbent bike in 86ºF with 30% humidity. Every 15 minutes each participant was given 250mL of water that was either very cold (34.7ºF) or room temperature (98.6ºF). Body temperature and heart rate were monitored throughout the exercise trials.
For the neutral trial (room temperature water), only 3 out of 10 MS participants completed the full 60 minutes of cycling while all 10 non-MS participants completed the full 60 minutes. All 7 MS participants that did not complete the full 60 minutes of cycling lasted longer for the cold trial (cold water), with an average of 30% increase in their times. However, there was no significant difference in absolute body temperature, change in body temperature during exercise, or heart rate.
These findings are interesting because while the participants’ bodies were put through more exercise for the cold water trial, they were able to tolerate it better with the very simple cooling mechanism of drinking cold water. The authors of the study noted that a rise in core temperature is not the only factor that leads to heat intolerance for MS patients. The perception of heat is a product of many different physiological and perceptual mechanisms, and more research needs to be done in these areas to further increase our understanding of what specifically influences heat intolerance for people with MS. Clearly, the thermoreceptors of the digestive tract have a more profound effect than previously thought!
This study provides a simple solution for fighting heat intolerance in people with MS. Other methods such as wearing a cooling vest or taking a cold shower/bath have been recommended in the past, but these options are not always necessarily practical options in everyday life. Drinking cold ice water when it’s hot seems intuitive, but the significance of being able to continue regular exercise for people living with MS is vital to their well-being. Anything that can help battle fatigue from overheating for individuals with MS is a huge plus, so having an easy tool that is backed by research is great!