Increases in submaximal cycling efficiency mediated by altitude acclimatization

Abstract

To investigate the hypothesis that respiratory gas exchange and, in particular, the O(2) consumption (VO(2)) response to exercise is altered after a 21-day expedition to 6,194 m, five male climbers (age 28.2 +/- 2 yr; weight 76.9 +/- 4.3 kg; means +/- SE) performed a progressive and prolonged two-step cycle test both before and 3-4 days after return to sea level. During both exercise tests, a depression (P < 0.05) in VO(2) (l/min) and an increase (P < 0.05) in minute ventilation (VE BTPS; l/min) and respiratory exchange ratio were observed after the expedition. These changes occurred in the absence of changes in CO(2) production (l/min). During steady-state submaximal exercise, net efficiency, calculated from the rates of the mechanical power output to the energy expended (VO(2)) above that measured at rest, increased (P < 0.05) from 25.9 +/- 1.6 to 31. 3 +/- 1.3% at the lighter power output and from 24.4 +/- 1.3 to 29.5 +/- 1.5% at the heavy power output. These changes were accompanied by a 4.5% reduction (P < 0.05) in peak VO(2) (3.99 +/- 0.17 vs. 3.81 +/- 0.18 l/min). After the expedition, an increase (P < 0.05) in hemoglobin concentration (15.0 +/- 0.49 vs. 15.8 +/- 0.41 g/100 ml) was found. It is concluded that, because resting VO(2) was unchanged, net efficiency is enhanced during submaximal exercise after a mountaineering expedition when the exercise is performed soon after return to sea level conditions.

Monitoring of total body water to examine the progress of acclimatization of runners at varying altitudes

“…Within the context of our general knowledge about mountain stays, where the literature suggests rather threatening dehydration (losses increased by ventilation and the excretion of urine) it shows that all athletes were well hydrated and the question is whether water retention is an indicator of the acclimatization process, or, conversely, lack of training process and therefore losses of water during physical exercise (Noakes, 2003;Basset & Howley, 2000;Lungby, 2012;Billat et al, 2003;Bunc, 2012;Saunders et al, 2004;Green et al, 2000;Legrand, 2005). Generally, in the acclimatization phase, we observed two critical periods: 4th-6th day of a stay, and 10th-12th day of stay (Gore et al, 2001;Green et al, 2000;Lungby, 2012;Saunders et al, 2004;Wilber, 2004 …”

“…Key factors influencing the organism and the training process at high altitudes are: decreasing barometric air pressure, decreasing partial pressure of oxygen (pO 2 ), decreasing air temperature (declining by about 1°C for every 150m of increased altitude), decreasing humidity, and increasing radiation (ultraviolet radiation increases by 20-30% for every 1000m (Basset & Howley, 2000;Katyama et al, 2003;Gore et al, 2001;Green et al, 2000;Levine et al, 2005;Morrison & Cooper, 2006;Neumann et al, 2000). The process of acclimatization at higher altitudes depends on the following factors: training level before arrival, physical condition, health and mental stability, altitude of the stay, altitude of personal workout, length of stay, volume and intensity of training load during stay, season and stage of preparation within the framework of the annual macrocycle, and drinking and dietary régime (Noakes, 2003;Green et al, 2000;Bragada, 2010).…”

“…The process is individual and can be monitored by objective parameters including HR, VO 2max , Lactate, Urea in blood serum, Hemoglobin level, Hematocrit level, etc. (Noakes, 2003;Wilber, 2004;Green et al, 2000;Neumann et al, 2005;Levine et al, 2005).…”

“…Disregard of the recommendations for acclimatization can disrupt the speed and quality of acclimatization, and can also lead to overload. In the opinion of some experts, assessments during adaptation to high altitude may be indicated by changes in body composition parameters (Lungby et al, 2012;Green et al, 2000).…”

Efficiency Variation in Cycling Exercise Related to Cadence and Work Rate Standardized by Ventilatory Threshold

“…The factors which have been pointed out as to aŠect the e‹ciency are working parts of body (Bunc and Heller, 1991;Kang et al, 1997), muscleˆber type Barstow et al, 1996), type of training (Marsh et al, 2000;Boone et al, 2010), altitude acclimatization (Green et al, 2000), body mass (Berry et al, 1993), physical maturity (Rowland et al, 1990), type of exercise (Bahr et al, 1991;Passˆeld and Doust, 2000) and so on. Quite a few investigators also have studied interactions between the cycling frequency and the output power on mechanical e‹ciency during sub-maximum cycling exercise (Foss and Hall áen, 2004;Lucia et al, 2004;Foss and Hall áen, 2005;Pierre et al, 2006).…”