Effects Of Hypoxic Exercise And Carbohydrate-electrolyte Solution Ingestion On Body Fluid Balance And Aerobic Capability

Hypoxic training, which has been shown to increase cardiopulmonary function,maximum oxygen uptake and skeletal muscle capillary, as effective approach forstudies aimed at evaluating altitude exercise has attracted attention of researchers onsports. Despite important role of dehydration in exercise, researchers generallyneglected it in hypoxic condition. The purpose of this study was to explore the effectof carbohydrate-electrolyte solution(CE) ingestion on body fluid balance and exerciseability in different O₂ concentration environments, and supply more experimental datafor rational CE ingestion in hypoxic training by measured relative indexes duringhypoxic or normoxic single bout of exhaustive exercise with or without rehydrationsolution, such as nude weight, serum osmolality, urine specific gravity, serum ionsconcentration, blood pressure, body temperature, blood lactate, exercise duration,heart rate and rating of perceived exertion(RPE). Therefore, we can guide athleticstraining by preventing and observing dehydration.Seven male students in college of physical education taked single bout ofexhaustive exercise on bicycle ergometer at 70%VO_2max in an artifical hypoxicroom(normobaric hypoxic environment and normobaric normoxic environment). Thesubjects were separated to 4 groups based on different oxygen concentration and thecondition of rehydration solution during exercise: normoxic control(NC); hypoxicexercise(HE); normoxic fluid(NF); hypoxic fluid(HF). The data after trainingcompared with that before exercise and analyzed by SPSS.ConclusionWeight-lost and raise of serum osmolality were observed in both 4 groups,specially in HE and NC groups and the serum osmolality recuperated within30minutes after training, which showed that dehydration in normoxic and hypoxicexercises and the rate of back to body fluid balance could be improved by CEingestion. The sweat exhausting rate during exercise of NF group was lower than thatof NC, while the contrary result showed in the compare between HF group and HEgroup. One possibility may be due to changes of subjects' sweat exhaustingmachanism under hypoxic exposure. It is suggested that rehydration was needed to improve the state of body hydration during hypoxic and normxic exercises. However,hypoxic rehydration differed from normoxia according to changes of physiologymechanism (especiall body fluid balance mechanism) caused by hypoxia.There was appreciable increase of serum [Na⁺] and [Cl^-] in NC and HE afterexercise; while decrease observed in NF and HF, and then decreased significantlywithin 30 minutes after exercise. It is speculated that this related to the lowconcentration of Na⁺ and Cl^- in supplementary. Increase of serum [K⁺] was present inall groups and was positive correlated with duration, especially significant in HE andHF, while sharp decrease of [Na⁺] was shown in HF at 30 minutes after training.The physiological mechanism is not clear, and further studies would be necessary toclarify the issue.With same exercise workload, HR-time curve of HE turned to move rightcompared with that of NC; there was deep degree of decrease of pressure afterexercise. Therefore, exercise workload same as under normoxia was relativelyenlarged under hypoxic exposure.HR-time curve of HF and NF turned to move right compared with those of HEand NC, there was small scope of blood pressure, there is a special function ofmaintain HR and BP by CE ingestion.Significant increase of blood lactate was observed in HE compared to NC, whichsuggested speed of lactate gather was faster in hypoxia; there were significantdecreases of blood lactate both in HF and NF compare to HE and NC. These resultsshowed that CE ingestion has certain action on appearance and clearance ofmetabolite. The blood sugar concentration in HE was higher than that in NC, perhapsdue to double stimulations of exercise and hypoxia which maintained excitation ofsympathetic-adrenal-system and accelerated Glycogenolysis. There was significantlyhigher increase of blood sugar in HF, which suggested that blood sugar concentrationcould be kept and hepatin could be saved by glucose uptake.