Study On Fatigue Assessment Of Young People By Near Infrared Spectroscopy Technique

Objective:Near infrared spectroscopy is used in exploring the lactic acid change situation of vastus medialis, vastus lateralis, rectus femoris and deltoid muscle in increasing exercise load. The aim is to explore the relationship between lactic acid and hemoglobin.Explore the relationship between the changes in the characteristics of the working muscle oxygen saturation and exercise intensity, and then comparing this evaluation index with the traditional indicators such as maximal oxygen uptake and heart rate(HR) and blood lactate, the aim is to explore the changes and correlation of each index, provide theoretical and practical basis for the arrangement of training content, provide the lossless for scientific evaluation of exercise intensity and no record of the real-time monitoring, judge the exercise-induced fatigue by monitoring changes of muscle oxygen saturation and master the training intensity of the tester.Methods:A total of 80 freshmen(20males and 20 females) and seniors(20males and 20 females) from Jilin Sport University are randomly selected. The tester carries out incremental load exercise on the power bicycle, to 50 W for first grade, pedaling speed control 60 r / min, adding 50 W every 3 minutes, gradually increasing until 12 minutes.The oxygen content changes of the vastus medialis, vastus lateralis, rectus femoris, deltoid muscle are continuously measured by the muscle oxygen monitor. At the same time, the blood lactic acid concentration is analyzed by the use of human and animal gas metabolic analyzer to measure the maximum oxygen uptake taking the end of each stage and exercise after the third, sixth, ninth, twelfth minutes to collect blood from finger twig.Results:(1) In the different intensity of exercise, the subjects’ energy metabolism and oxygen intake increase, their heart rate is higher. The experimental results show that with the increasing of exercise load, the intake of heart rate and oxygen increases.(2) In the different intensity of aerobic exercise, heart rate, oxygen uptake and blood lactate concentration increase with the increase of exercise load. At the same time, blood flow velocity of skeletal muscle tissue increased and oxygenation blood red protein content decrease with the increasing of exercise load.(3) In the different intensity of exercise, regularity changes in blood volume, oxygenated hemoglobin and reduces hemoglobin content of skeletal muscle tissue to the subjects. The skeletal muscle blood lactic acid increases with exercise intensity increasing. The oxygen demand and oxygen uptake correspondingly increase.(4) In the different intensity of exercise, there is correlation between muscle oxygen saturation and heart rate, oxygen intake and blood lactic acid. With the increasing of exercise load, the energy consumptions of the muscle tissue significantly improve. But the increasing of the blood flow can not meet the muscle tissue for energy material needs. Therefore, experimental results show that muscle tissue oxygenation of hemoglobin content and muscle oxygen saturation decrease. At the same time, heart rate, oxygen intake and lactic acid increase with exercise load increasing.(5) In the different intensity of exercise, the inflection point of the relative change of the oxygen saturation of the work is related to the level of the individual lactic acid threshold. The muscle lactate accumulation leads to oxygen dissociation curve shifts to the right is one of the reasons for the sharp decline in the muscle oxygen saturation with the high intensity exercise and a sharp increasing in blood lactate with the increase of strength.Conclusion:(1)This study attempts to explore the relationship between the relative changes of muscle oxygen saturation and heart rate, blood lactate concentration and oxygen content in skeletal muscle tissue during the four stage of incremental load exercise. The aim is to provide practical basis for the relative changes of muscle oxygen saturation with nondestructive monitoring. It is feasible to introduce the new monitoring technology and evaluation index to the physiological function evaluation of the athletes and the physiological evaluation of the training effect.(2) With the increasing of exercise load, exercise intensity and exercise time, the increasing of blood volume and the decreasing of the content of oxygenated hemoglobin and the blood lactic acid concentration increase greatly in the muscle tissue. This method is feasible for evaluating the ability of the athletes to work during the incremental load. This provides a new way to replace the damaged blood lactic acid by nondestructive testing method in the physical training of the future.(3)The experimental results, the blood lactate indicators show that muscle fatigue occurs in the time of 6-9 minutes. At this time, the average value of the muscle oxygen saturation of the four muscles is between 43.33%-35.08%.The maximum value is 59% and the minimum value is 23.84%. In this range, the exercising muscles begin to fatigue by preliminary determination. At the twelfth minutes in the increasing experiment, the subjects are exhausted. The minimum value of muscle oxygen content is 22.91%.This conclusion provides a reference value for the exercise training to avoid muscle damage. However, subjects do incremental compliant motion on the power bike, the muscle force is different. So it is necessary to have a large number of experiments to prove it.