Author and graduation date: Amy KISSELL, May, 2000

Committee members: Michael J. Buono (Chair), Fred W. Kolkhorst, Loffaine T. Fitzsimmons, Kim Prisk

Thesis title: Breath-hold Training and Its Effects on Chemosensitivity and Exercise Ventilation

This study assessed the potential benefits of exercise breath-hold training (EBHT) on chemoreceptor sensitivity and exercise minute ventilation (VE). Thirteen healthy male and female volunteers, between the ages of 18 and 40 yr, were studied. The participants were divided into three groups: endurance trained (mean (± SD) V02max (ml/kg/imin) of 61.8 + 6. 1), untrained (mean V02max values of 35.3 + 3.9), and controls (mean V02max values of 56.4 + 7.3). Each participant exercised on a cycle ergometer at 4 progressive workloads for 5 minutes: 50 W, 100 W, 150 W and 200 W. VE, V02max, and VCO2 values were averaged every 20 seconds during the exercise test. The exercise test continued until exhaustion in order to determine the V02max. For the post-test, the exercise protocol was stopped after 200 W. Blood lactate levels were measured at the end of each five-minute workload and 3 minutes post-exercise. Heart rate (HR) was measured every minute using a Polar heart rate monitor. Participants also completed hypercapnic ventilatory response (HCVR) and hypoxic ventilatory response (HVR) tests. Each participant in the endurance and untrained group then completed 5 continuous days of exercise breath hold training (EBHT) and control participants received no treatment. EBHT consisted of alternating 30 seconds of pedaling at 50 W while holding one's breath with a 30 second rest period for one hour daily. Results of the incremental exercise test indicated that both VE and VO2 increased progressively with each workload for all groups (p < 0.001). However, there were no significant differences in VE or VE/VO2 between pre-testing and post-testing for either the endurance group or the untrained group (p > 0.01). Results of the ventilatory control tests also indicated no significant change in VE at a PCO2 of 60 Torr for the HCVR test or VE at an SaO2 of 75% for the HVR test for either the endurance or untrained groups after the EBHT intervention. In conclusion, the results of the current study suggest that five days of EBHT does not decrease chemoreceptor sensitivity. In fact, all measures of chemoreceptor sensitivity (VE, VE/VO2, HCVR and HVR) tested were not significantly affected by the five days of EBHT in either the endurance-trained or the untrained participants. This study also suggests that while endurance athletes do breathe less during exercise they do not have lower chemoreceptor responses at rest when compared to untrained participants. Thus, the current study does not offer support to recommend the addition of EBHT to an endurance athlete's training regime.

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