D-24 Free Communication/Poster - Altitude and Hypoxia: MAY 28, 2009 1:00 PM - 6:00 PM ROOM: Hall 4F
It is assumed that the excellent performance of Kenyan runners is mainly due to a high running economy in connection with high VO2max. To explain underlying physiological reasons research mainly focused on muscular oxygen consumption.
PURPOSE: To investigate basic factors of oxygen transport, i.e. total hemoglobin mass (tHb-mass), blood volume (BV) and heart size in elite Kenyan runners and adaptation processes of these parameters during a sojourn at lowland.
METHODS: Ten Kenyan runners (group K; competing between 1.500m and marathon) living and training at moderate altitude (∼2100m) performed a 6-weeks lasting training camp at 350m in Germany. Training (volume ∼210km/week) was similar to that normally performed in Kenya. tHb-mass and BV were determined using the optimized CO-rebreathing method on the first day after arrival to Germany and weekly during their whole stay. In addition BV and haemoglobin concentration [Hb] were also examined before departure at altitude. VO2max was determined in three field tests and running economy in a laboratory test on a treadmill. 11 German elite runners served as a control group (group G).
RESULTS: The Kenyan runners had a significantly lower body mass (K 57.2 ±7.0kg; G 66.5 ±6.3kg) and BMI (K 18.5 ±0.9; G 20.4 ±0.9). Relative VO2max did not differ between the groups (K 71.5 ±5.0 ml/kg/min; G 70.7 ±3.7 ml/kg/min) and absolute VO2max did not change during the 6 weeks at low altitude. Relative tHb-mass (K 14.2 ±1.0g/kg; G 14.0 ±0.7g/kg) and BV (K 101.9 ±4.5ml/kg; G 99.6 ±5.8ml/kg) were similar in both groups but continuously decreased in K during the stay at lowland (absolute tHb-mass from 813 ±90g to 767 ±90g, p<0.001; BV from 5828 ±703ml to 5513 ±708ml, p<0.01). [Hb] tended to decrease (-0.7 ±0.7g/dl) when commuting altitude but did not differ at sea level between the groups (K 15.4 ±1.0g/dl, G 15.5 ±1.2g/dl). The relative heart volume was slightly lower in the Kenyans (K 14.0 ±1.5ml/kg; G 15.2 ±2.0ml/kg). Running economy was higher (p<0.05) in K at speeds of 18km/h and above and can partly be attributed to the smaller calve circumference (p<0.001) and lower BMI (p<0.001).
CONCLUSIONS: The excellent running performance of Kenyans is not due to an improved oxygen transport system but due to a lower demand of oxygen at higher speeds compared to German runners.
Supported by BISp, No.VF070121/05-06.