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在一些耐力性的运动中,如长跑、长距离骑自行车、长距离游泳、竞走时,开始后有一段时间感到特别气急、难受,甚至心慌、头晕、四肢无力,想停下来歇歇、不想再继续运动下去了。这种现象,在运动生理学上叫做“极点”。为什么在运动中会出现“极点”呢?原因是刚开始运动时,支配肌肉、关节等运动器官的神经兴奋性较高,起动较快,能迅速从安静状态进入工作状态,而支配心跳、呼吸等内脏器官的神经兴奋性较低,起动较慢、不能迅速的由安静状态进入工作状态,输送的血液和吸入的氧气难以满足身体剧烈运动时的需要,而且体内的代谢产物也不能及时排出。身体在这种缺氧的情况下进行剧烈运动,其代谢产物进入血液中,刺激呼吸中枢和血液循环系统,引起心慌、气短、头晕、胭闷、四肢无力等一系列不适应的现象。有些人不了解产生“极点”的原理,出现“极点”后,心中很是害怕,不敢继续运动,怕影响身体健康,这种担心是不必要的。
In some endurance sports, such as long distance running, long distance cycling, long distance swimming and walking, some time after the start is particularly impatient, uncomfortable, or even flustered, dizzy, weakness, want to stop and rest, do not want to Keep moving. This phenomenon is called “pole” in exercise physiology. Why do we find “pole” in exercise? The reason is that at the beginning of exercise, the excitability of the nerves that dominate muscles, joints and other organs of movement is higher, the activation is quicker, and the working state can be rapidly brought from a quiet state, while the dominant heartbeat , Respiration and other internal organs of the lower nerve excitability, slow start, can not quickly enter the working state from a quiet state, the delivery of blood and inhaled oxygen is difficult to meet the needs of the body during strenuous exercise, and the body’s metabolites can not be timely discharge. The body in this case of hypoxia strenuous exercise, the metabolites into the blood, stimulate the respiratory center and the blood circulation system, causing palpitation, shortness of breath, dizziness, nausea, limb weakness and a series of incompatible phenomena. Some people do not understand the principle of producing a “pole”. After “pole” appears, they are very afraid in their hearts and afraid to continue their exercise in fear of affecting their health. Such fear is unnecessary.