A Single High-Altitude Training Bout Improves High-Altitude Aerobic Performance Following 1 Week of Low-Altitude Training

Abstract

Consecutive bouts of aerobic exercise at high-altitude are known to improve subsequent aerobic exercise performance at high altitude due to a variety of acute and chronic adaptations referred to as altitude acclimatization. However, it is unclear whether these benefits can be elicited by a single bout of high-altitude exercise followed by several days of training at lower altitude. PURPOSE: We investigated whether a single bout of hill running exercise performed at high-altitude improves running performance, arterial oxygen saturation (SaO2), hematocrit (HCT) and perceived exertion (RPE) during a strenuous timed run at high-altitude performed 1 week following the training stimulus. METHODS: Participants were well-trained competitive runners (VO2max 52 ± 2 ml/kg/min, aged 42 ± 5 yrs, n = 8) living in Fort Collins, CO (5003 ft) that were naïve to higher altitudes for at least 8 weeks. All were training regularly (66 ± 3 miles/wk) and refrained from any non-prescribed altitude exposure for the duration of the study. Baseline testing consisted of a timed run on the Mt. Evans Scenic Byway in Colorado (11.5 miles at 11500-14100ft) followed by one week of training in Fort Collins. Runners were then randomized to perform a 12 mile hill running workout in Fort Collins (LOW; 6000-7000ft, n = 4)) or Mt. Evans (HIGH; 13100-14100ft, n = 4). All runners then engaged in 1 week of routine training in Fort Collins followed by a post-test run at Mt. Evans that was identical to the baseline test. RESULTS: The HIGH group experienced a 4.7 ± 2 % improvement in high-altitude run time (7.1 min faster; P = 0.09), while the LOW group ran 0.5 ± 1.5 % (1.3 min) slower (P = NS). Mean SaO2 was 3% higher in the HIGH in the post vs. pre-test at 14100ft (P = 0.02), but 1% lower in the LOW group (P < 0.05 for group difference). In addition, SaO2 tended to stabilize at higher levels in the HIGH vs. LOW (+2.25% vs., -2.99%, respectively) following completion of the post-test at 14100ft (P = 0.10). HCT tended to increase in both groups from pre to post testing, but there were no differences in HCT, or RPE, between HIGH and LOW groups. CONCLUSIONS: A single high-altitude training bout prior to 1 week of low-altitude training improves subsequent aerobic performance and arterial O2 saturation at high-altitude, while a single bout performed 2 weeks prior to testing is ineffective.