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Mikel Egaña Trinity College Dublin • Barometric pressure decreases as altitude increases • Air always contains: 20.93% O2, 0.03% CO2, 79.04% N2 • Cold air holds little water, so air at altitude is dry: risk of dehydration Altitude training for sea-level performance 1 Increases at rest and during exercise To prevent alkalosis: • CO2 clearance increases • Kidney excrete bicarbonate ions • Blood pH increases • More acid remains in the blood • Respiratory alkalosis • Alkalosis is reversed Haemoglobin saturation decreases from 98% (sea-level) to 90-92% (2,500m) Altitude training for sea-level performance Partial pressure (mmHg) Sea level 2,439 m Arterial PO2 100 60 Muscle PO2 40 40 Diffusion gradient 60 20 VO2max decreases as altitude increases i.e. at Mount Everest VO2max is 10 to 25% of its value at sea level! Altitude training for sea-level performance 2 Blood volume: • Plasma volume initially decreases (dehydration), then plateaus. • Lack of O2 stimulates the release of erythropoietin after 3h (peak 24-48 h) Stimulates erythrocyte (RBC) production. • So, ultimately blood volume back to normal Cardiac output (CO): • At rest and mid submaximal exercise CO increases slightly Initially: SV is decreased and HR increased After a few days: a-v O2 diff increased, so less demand for HR • Maximal exercise: both SV and HR lower, so maximal CO decreases Altitude training for sea-level performance • For a given submaximal work rate blood lactate concentration increases • However, maximal lactate concentration decreases (paradigm) • Increase in: • Capillary supply Decrease in: Muscle fiber area Total muscle area Glycolitic enzyme activity Probably due to loss of appetite, weight loss Altitude training for sea-level performance 3 • Activities that require high demands on O2 transport and aerobic energy system most affected. • The decrease in VO2max with initial exposure to altitude doesn’t improve much after weeks of exposure • So, important to reach high VO2max values before altitude exposure • Sprint (<2 min), jumping and throwing activities generally not impaired at moderate altitude (Mexico 1968) Altitude training for sea-level performance Athletes who normally train at sea level, but must compete at altitude. Options: a) Compete within 24 h of arrival at higher altitudes: • No acclimatization, but avoidance of detrimental responses to altitude such as dehydration and sleep disturbances b) Train at altitude (1,500-3,000 m) for at least 2 weeks (For appropriate acclimatization ~4 to 6 weeks) • Initial intensity: 60-70% of sea-level intensity • Progress to full intensity within 10-14 days c) For team sports requiring considerable endurance (football, hockey, basketball) • Intense aerobic training at sea level to reach high VO2max values • So, at altitude they will perform at lower relative intensities Altitude training for sea-level performance 4 • Most studies show no improvement in sea-level performance following altitude training. • Few studies have shown post-altitude improvements at sea level, but poorly controlled (subjects not well trained) • Difficult methodological problems: • Athletes unable to train at same volume and intensity as at sea level (CV function decreased) • Often athletes dehydrate and lose fat-free mass Brosnan et al. 2000 Altitude training for sea-level performance Study 1: Hi-Low Levine BD et al. JAP 1997 Altitude training for sea-level performance 5 Study 1: Hi-Low Levine BD et al. JAP 1997 Results for the HI-LO group: Main improvement in performance (5000 m): 1.4% Improvement in VO2max: 2.5% Altitude training for sea-level performance Study 2: Hi-Hi-Lo (elite athletes) Results for HI-Hi-LO group: Main improvement in performance (3000 m): 1.1% Improvement in VO2max: 2.3% Stray-Gundersen J et al. JAP 2001 Altitude training for sea-level performance 6 Comparison of the two studies: ΔEpo,% ΔHb, g/dl ΔVO2max (ml/kg/min) Δ Performance, % Elite runners (14M, 8F) (study 2, 2001) 103±74 1.0±1.1 2.3 ±2.6 1.1 College runners (18M, 8F) (study 1, 1997) 59±40 1.1 ±0.7 2.5 ±2.4 1.4 Altitude training for sea-level performance So, HI-LO method favourable results, but difficulties: Logistically + financially Other approaches: • Hypoxic tents (sleeping devices) or even hypoxic living apartments • • Robach P et al, EJAP 2006 (elite swimmers): • 13 day training while living & sleeping in hypoxic rooms (16h /day) • No improvements in VO2max or swimming performance (2000m) Brugniaux JV et al, JAP 2006 (elite athletes) • 14 day training while living & sleeping in hypoxic rooms (14h /day) • Improvements in VO2max and VO2 at Ventilatory Threshold Altitude training for sea-level performance 7 Hypoxic rooms (‘Hi-Lo’) (elite athletes) Results for HI-LO group: - Improvement in VO2 at VT: 18.1% Post 1; 15.9% Post 2 - Improvement in VO2max: 7.1% at Post 1; 3.4% Post 2 Possible reasons: - Post 1: RCV incresed 9% - Post 2: normal RCV; so, due to training potentiation Brugniaux JV et al, JAP 2006 Altitude training for sea-level performance Intermittent normobaric hypoxia Julian et al, JAP, 2004 (runners): 5:5 min hypoxia-to-normoxia ratio for 70 min 5 times/wk x 4wks Hypoxia: fraction of inspired O2: 0.12(wk-1), 0.11 (wk-2), 0.10 (wk-3&4) Results showed: No improvements in performance (3000 m) No improvements in VO2max Due to a lack of increase in Hb and erythropoietin. Julian CG et al. JAP 2004 Altitude training for sea-level performance 8