The Effects Of HiHiLo On Skeletal Muscle Oxygen Utilization

Living high-exercise high-training low (HiHiLo) is frequently used by competitive athletes and researchers to improve sea-level performance. Living high-training low plus exercise at moderate altitude (HiHiLo) is used to get better effects. Exposture to hypoxia result in central and peripheral adaptions that improve oxygen delivery and utilization. Moreover, hypoxia exercise may increase the training stimulus, thus magnifying the effects of training. In our knowledge, most researches investigated the effects of HiHiLo on human by observing cardiovascular changes. The present study was designed to test HiHiLo’s effects on muscle oxygenation and its mechanism by observing the change of muscle oxygenation measured by NIRS after 4 weeks HiHiLo.64 male sports university students stay at hypoxic room for 10 hour per day for 4 weeks. Every week subjects performance 30min cycle exercise three times, the intensity was 75% VO2max . Before and after 4 week, each subject underwent incremental cycling to exhaust in normaxia while oxyhemoglobin saturation (SpO2) and blood lactate concentration (BLa) were measured. We also measured muscle oxygenation with continuous-wave near infrared spectroscopy (NIRS) synchronously. Furthermore, muscle oxygenation of persistent cycling exercise was measured at first and last training in hypoxia of HiHiLo. The result showed that:1. When performed incremental cycling exercise in normoxia subjects’ muscle oxygenation decreased by work rate.2. During hypoxia exercise subjects’ muscle oxygenation decreased significantly initially and range of decrease was slowly as exercise persistence, muscle oxygenation increased over resting levels after exercise finished.3. Subjects’ muscle oxygenation showed increased trend while performed same work load after 4 weeks. This fact clue on that HiHiLo developed the oxygen utilization of muscle.4. Blood lactate concentration- intensity curve moved to right after 4 weeks. It means muscle’s capability of oxygen delivery and utilization developed.5. Subjects’ muscle oxygenation that performed persistent exercise in hypoxia decreased slowly significantly after HiHiLo. It indicated muscle’s capability of oxygen delivery and utilization had been developed.6. Relationship between blood lactate concentration and muscle oxygenation/oxyhemoglobin saturation was negative correlation. This clued to that the development of eliminating lacate in skeletal muscle related to improvement of oxygen delivery and utilization in whole body.In conclusion, 4 weeks of HiHiLo training results in improvement of oxygen delivery and utilization of skeletal muscle. Because of its uninvasive characteristic, muscle oxygenation measured by NIRS probably is regarded a index of training control and availability.