Effects Of Simulated 4000m Hypoxic Exposure On Skeletal Muscle Oxygen Content In Squat Training With Different Intensities

Objective: To explore the relationship between muscle oxygen content and lower limb strength training intensity under hypoxic and normoxic conditions,and to provide a possibility for finding new strength monitoring indicators.Methods: Twelve eligible subjects were selected for squatting training with three different load intensities under normoxia and hypoxia respectively.Oxymon Mk III near infrared imaging system and Polar Team Pro team heart rate detector were used to monitor muscle oxygen content and heart rate during exercise.The relevant indexes of muscle oxygen content were obtained for analysis,and the variation rule of muscle oxygen related values under different oxygen partial pressure and different training intensity was explored.Result: 1.Under normal oxygen,at the end of the fifth squat(15s),the inflection point of muscle oxygen change appeared at the intensity of 9RM and 15 RM,and then the dynamic balance was maintained.The downward trend line functions of oxyhemoglobin in the first 15 seconds of 3RM,9RM and 15 RM were Y1 = 5.66 x + 13.95,y2 = 3.34 x + 11.56,Y3 = 2.96 x + 11.13 and the downward rate was K1 > K2 >K23.Therefore,the greater the intensity of oxyhemoglobin under normal oxygen,the faster the decrease of oxyhemoglobin.The three load intensities of 3RM,9RM and 15 RM showed similar trends under hypoxia.The trend line functions were Y1 =-6.14 x + 10.33 y2 =-3.41 x + 7.10,Y3 =-3.41 x + 7.10,and the rate of decline was K1 > K2 > k3.The higher the intensity of hypoxia,the faster the decrease of muscle oxygen content.2.Taking three squats(9s)as a unit of exercise,the statistics of oxyhemoglobin showed that there were significant differences in the mean of the change of oxyhemoglobin in three squats before three different loads(P < 0.05),and there was a high correlation between the change of oxyhemoglobin and the intensity of exercise load(r = 0.9).The higher the intensity of exercise,the lower the value of oxyhemoglobin.3.Comparing the changes of oxygen content of hypoxic and normoxic muscles under three different intensities,it was found that there were significant differences in the changes of oxyhemoglobin between hypoxic strength training and normoxic strength training under three different intensities(P < 0.05).At the same load intensity,the decline rate of oxyhemoglobin under hypoxia was higher than that under normoxia,and the red eggs under hypoxia and normoxia were also found to have significant differences.There was a high correlation between white change(0.5 < R = 0.8 < 1.0).4.Hemoglobin oxygenation remained negative for three consecutive squats under hypoxia,indicating that muscle was always in a more serious hypoxic state during strength training under hypoxia,which could improve the aerobic and anaerobic exercise ability of the body.Conclusion 1.Strength training under hypoxia can stimulate muscles more obviously,and can cause long-term hypoxia of local muscles.2.Compared with normal oxygen,strength training under hypoxia leads to a faster decline in muscle oxygen content.3.There is a high correlation between the intensity of exercise load and the decrease of muscle oxygen content in strength training.It shows that the content of muscle oxygen decreases with the increase of muscle oxygen intensity.Therefore,muscle oxygen can be used as a new index to monitor the exercise load in the process of strength training.