Type of Document Dissertation Author Austin, Krista Gail Author's Email Address email@example.com URN etd-07112005-120650 Title The Effects of Intermittent Hypoxia on Hematological Markers and Exercise Performance Degree Doctor of Philosophy Department Nutrition, Food, and Exercise Science, Department of Advisory Committee
Advisor Name Title Emily Haymes Committee Chair Lisa Eckel Committee Member Lynn Panton Committee Member Keywords
- Intermittent Hypoxia
Date of Defense 2005-06-20 Availability unrestricted Abstract
The primary purpose of this study was to examine the erythropoietic response to intermittent hypoxic exposure (IHE) vs. intermittent hypoxic training (IHT). A secondary purpose was to assess the effects of IHE and IHT on time trial performance (TT), maximal oxygen carrying capacity (VO2max), and submaximal exercise capacity. Six cyclists and three triathletes participated in two experimental normobaric hypoxic trials (IHE and IHT) and a control (CTR) period of 28 days. The two experimental normobaric hypoxic trials were completed at 14.4% O2 concentration (3,000m) and consisted of: 1) a resting passive exposure in a seated position (IHE) and 2) cycling exercise at ~60-70% of heart rate reserve. Assessment of erythropoietin (Epo), free testosterone (FT) hemoglobin (Hb), hematocrit (Hct), reticulocytes (Rct), serum iron (SI), total iron binding capacity (TIBC), transferrin recptor (sTfr), ferritin (SF), total plasma proteins (TPP), and plasma osmolality (Posm) was taken 1 day prior to the start of each experimental trial and control period, and on days 1, 5, 14, 28 and 1 day after each of these periods for all participants. Evaluation of VO2max, power output at the lactate threshold (LT), submaximal exercise capacity (oxygen uptake [VO2], ventilation rate [Ve], heart rate [HR], arterial oxgen saturation [SaO2] and blood lactate [HLa]) and TT was completed before and after each 28 day period.
Results of a 3 x 6 ANOVA for measures of Epo, Hb, Hct, Rct, SI, TIBC, sTfr, SF, TPP and Posm did not demonstrate any significant trial by time interactions. A significant interaction between time and trial for FT was found; however, results of a one-way ANOVA conducted for each condition did not reveal any significant effects for IHE, IHT or CTR. A main effect for time was demonstrated for SF; however, results of a one-way ANOVA revealed no significant differences between time points when multiple comparisons were corrected utilizing the Bonferroni procedure.
Results of a 3 x 2 ANOVA for measures of performance did not reveal any significant trial by time interactions for VO2max, LT, submaximal VO2, HR, Ve and SaO2. A significant trial by time interaction was found for HLa at 30 minutes of exercise. HLa was significantly lower following IHT when compared to pre-exposure values. A significant main effect for condition was demonstrated at 30 minutes for SaO2. SaO2 was significantly lower during the IHE condition when compared to IHT. A significant trial by time interaction was found for TT. TT was significantly faster following IHT when compared to pre-exposure times. Significant main effects for time were found for LT, maximal heart rate and maximal HLa at 0, 2 and 10 minutes post exercise. The LT was significantly higher in the post time period when compared to pre testing values. Maximal heart rate and HLa at 0, 2 and 10 minutes in the post time period were significantly lower when compared to pre testing values .
Further statistical analysis of the variables of Hb, Hct, LT, VO2max, TT and submaximal exercise performance was performed on those individuals who maintained an SaO2 < 92% during IHE (n =6) and IHT (n = 7). This was to determine a possible cause effect for the improvement in time trial performance. No significant differences in Hb, Hct, VO2max or submaximal VO2 were found for IHE or IHT. IHE did not demonstrate significant differences in TT, LT, and submaximal HLa values. IHT demonstrated a significantly higher LT, significantly lower HLa values at 15 and 30 minutes of exercise and a significantly faster TT. Therefore, it was concluded that the improvement in TT was a result of decreased lactate production allowing for a higher power output to be sustained. It is concluded that IHT provides greater gains in endurance performance than training at sea level, and that IHE does not alter factors related to enhancement of endurance performance.
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