Effects of Cooling on Exercise Performance in an Elite Athlete with MS.
|Title||Effects of Cooling on Exercise Performance in an Elite Athlete with MS.|
|Publication Type||Journal Article|
|Authors||Alquist AD, Kraft GH, Barnard M|
We have learned through our recent cooling-and exercise- investigations that acute body cooling and chronic resistance training can independently improve motor function and lessen reported disability among MS patients. To test the hypothesis that body cooling will reduce exercise-induced symptoms and increase working capacity in MS we exposed a 32 year old, female, elite-cyclist (EC) with relapsing remitting MS and Uhtoff's phenomenon to 60 minutes of low (758F) and high (558F) cooling prior to a maximum leg-cycle exercise test. Methods: Each experiment consisted of three phases: cooling phase (60 min), pre-exercise stretching phase (15 min) and the exercise phase (time to exhaustion plus 5 min). The primary outcome variables to evaluate differences due to the cooling levels include: (1) maximum cycling time, (2) maximum oxygen consumption, (3) respiratory quotient (RQ), (4) time to anaerobic threshold and (5) oxygen pulse (systemic efficiency parameter). Every 5 minutes throughout the cooling phase we recorded EC's: (1) heart rate, (2) blood pressure, (3) body temperature and (4) perceived- comfort. At each interval we also measured: (1) coolant ¯ow-rate, (2) line-pressure, (3) garment inletand (4) garment-outlet temperature. Every 30 s throughout the exercise period we recorded: (1) heart-rate, (2) body temperature, (3) rate of O2 consumption, (4) rate of CO2 production, (5) minute ventilation, and (6) respiratory rate. Results: Heat exchange was 2.5 times greater at 558 cooling (58.3 watt-h) vs 758 cooling (22.7 watt-h). This higher cooling level caused a 1.08F drop in her body temperature (vs +0.68 at 758) which resulted in only a 0.18F increase in body temperature (vs +1.78 at 758) at exhaustion. Maximum cycling time was 7.1% higher, RQ was 6.4% lower at VO2max, time-to-anaerobic threshold was 15.4% longer and oxygen pulse was 10.5% higher at peak work output (225 watts) after cooling at 558F for 60 min. Conclusion: Performance and physiologic parameters indicate a more efficient transfer of energy (metabolism) while exercising after the higher cooling level. Lowering body core temperature before exercise appears to provide protection against the increased heat production caused by sustained elevated metabolism. Subjectively, EC's exercise-induced Uhtoff's phenomenon occurred much later in the exercise test and her perceived exertion was lower at each workload after the higher cooling.