SOME ADAPTATIONS TO ALTITUDE OCCUR INDEPENDENTLY

LaChapelle, J. A., Grossmann, E. C., Thurston, D., Nelson, J. L., Doan, B. K., & Brothers, M. D. (2010). Altitude-related differences in running economy among sea level residents during 46 weeks at moderate altitude. Presentation 1041 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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This study assessed differences in running economy between former sea-level and moderate altitude Ss during 46 weeks of chronic residence at the moderate altitude location of the U.S. Air Force Academy (USAFA). Males from either sea-level (under 330 m; N = 44) or moderate altitude (N = 11) had their running economy repeatedly assessed at multiple velocities (6-9 mph) on five separate occasions over 46 weeks at USAFA. Changes in total hemoglobin mass were also measured via the optimized CO re-breathing protocol. Running economy and total hemoglobin mass were examined for significant correlations. Based on previous research, half the sea-level Ss were supplemented daily with 100 mg ferrous sulfate in a double-blind, placebo-controlled design.

Sea-level Ss had significantly worse running economies compared to their moderate altitude peers after 8-10 weeks at moderate altitude at all velocities. Although all Ssí running economy changed significantly over time, the altitude-related difference became non-significant after ~16-18 weeks. There was no difference in running economy as a result of iron supplementation. While all sea-level Ss significantly increased their total hemoglobin mass with time, total hemoglobin mass peaked at +15 weeks in the iron group, and +19 weeks in the placebo group. Despite changes in both running economy and total hemoglobin mass among sea-level Ss residing at moderate altitude, there were no significant correlations between total hemoglobin mass and running economy.

Implication. Significant altitude-related differences existed in running economy and total hemoglobin mass for ~15 weeks at USAFA, but these parameters were not related. Chronic moderate altitude acclimatization results in changes to both running economy and total hemoglobin mass, but unique adaptations underlie each.

Altitude adaptation causes alterations in performance economy, probably through biomechanics. Consequently, altitude training is likely to be disruptive rather than facilitative or neutral because it disrupts both skill (movement efficiency) and physiology, each adapting independently.

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