and on a slightly different tack, the study below suggests that altitude living can help economy. a previous Japanese study showed similar results, but thre are some studies that show no effect. These sorts of studies may help provide clues as to what physiological/biochemical factors underlie economy. for example, the P:O ratio (energy obtained per mole of O2) may change. previous studies of high altitude natives in Peru showed that they have remarkable economy.
Influence of "living high-training low" on aerobic performance and economy of work in elite athletes
Schmitt L, Millet G, Robach P, Nicolet G, Brugniaux JV, Fouillot JP, Richalet JP
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY 97 (5): 627-636 JUL 2006
Abstract: This study tested the effects of "living high-training low'' (Hi-Lo) on aerobic performance and economy of work in elite athletes. Forty endurance athletes (cross-country skiers, swimmers, runners) performed 13-18 consecutive days of training at 1,200 m altitude, by sleeping at 1,200 m (LL, n = 20) or in hypoxic rooms with 5-6 nights at 2,500 m followed by 8-12 nights at 3,000-3,500 m (HL, n = 20). The athletes were evaluated before (pre-), one (post-1) and 15 days (post-15) after Hi-Lo. Economy was assessed from two sub-maximal tests, one non-specific (cycling) and one specific (running or swimming). From pre- to post-1: VO2max increased both in HL (+ 7.8%, P < 0.01) and in LL (+ 3.3%, P < 0.05), peak power output (PPO) tended to increase more (P=0.06) in HL (+ 4.1%, P < 0.01) than in LL (+ 1.9%). At post-15, VO2max has returned to pre-values in both groups, PPO increased more (P < 0.05) in HL (+ 8.3%, P < 0.01) than in LL (+ 3.8%), VO2 and power at respiratory compensation point (RCP) increased more ( P < 0.05) in HL (+ 9.5%, P < 0.01 and + 11.2%, P < 0.01) than in LL (+ 3.2 and + 3.3%). Cycling mechanical efficiency (8-5%)and economy during specific locomotion (7-7%) increased (P < 0.05) in both groups. This study shows that, for a similar increase in VO2max; HL had a greater increase in PPO than LL. The efficiency of Hi-Lo is also evidenced 15 days later by higher VO2 and power at RCP. This study emphasizes that during the post-altitude period, economy of work greatly increases in both groups.