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LOWER BODY VS. WHOLE BODY PRECOOLING

Limitations

I n t h e p r e s e n t s t u d y , m e a n T b w a s e s t i m a t e d b y t h e B u r t o n e q u a t i o n ( 5 ) , w h e r e i n T r e i s g i v e n t h e w e i g h t factor of 0.65, and mean Tsk is given the weighting factor of 0.35. The Burton equation was used because of the higher weighting of Tsk, because during a cold stress, especially during water immersion, skin tem- perature is more important in thermal balance. Al- though other weighting systems (e.g., 0.8 Tre and 0.2 mean Tsk or 0.9 Tre and 0.1 mean Tsk) used in the literature slightly alter the calculated mean Tb value, using them would not affect the interpretation of the data comparing the two treatments. i n g

Water immersion to the level of the neck alters body fluid balance and cardiovascular responses while in the water (9). However, we did not observe the character- istic baroreceptor-mediated decrease in heart rate due to increases in central blood volume during water im- mersion to the level of the neck because of the overrid-

˙ ing effect of the 20°C water on increasing M. It is

therefore unlikely that differences in depth of water immersion per se had profound effects on the thermal or cardiovascular responses during exercise after wa- ter immersion.

Conclusion

In conclusion, WBI and LBI attenuated Tc increases during submaximal exercise by producing a reduction i n T r e , w i t h W B I p r o d u c i n g a s l i g h t l y g r e a t e r c o o l i n g ˙ effect. Both treatments produced similar net S over the

entire protocol. However, LBI minimized metabolic increases and negative perceptual effects associated with WBI. Because of its similar thermal effect, re- duced metabolic and perceptual effects, and ease of use, LBI should be the preferred precooling method for patient populations that demonstrate impaired physi- cal function with increased internal temperature.

We acknowledge the technical support of Bob Shafer. We also thank all of the study participants for their time and cooperation.

This study was supported in part by a grant from the National Multiple Sclerosis Society.

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J Appl Physiol VOL 94 MARCH 2003 www.jap.org

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