问题体育课上,引体向上对许多同学来说是一个老大难问题,在做引体向上时除了力量因素外,技巧也很重要,做引体向上成绩比较优秀的同学,他们在曲臂提拉身体前都会有展腹、下肢后摆、收腹、下肢前摆一系列动作。那么,下肢后摆到多大角度时,手臂最省力呢?下肢前摆到多大角度时制动,对向上拉帮助最大呢?下面利用数学、物理和生物知识来分析解答这个体育问题。分析与无生命的物体不同,人体的运动是受意识控制的运动,因此 In physical education, physical education is a long-standing problem for many students. In addition to strength factors, skills are also very important when doing chin-ups. Students who do relatively good chin-ups have a lot of fun. Before pulling the body, there will be a series of movements such as belly-opening, lower-limb swinging, abdomen lowering, and lower limbs. Then, when the lower limbs are placed at a large angle, the arm is the most labor-saving. When the lower limb is placed at a large angle, it is braked. What is the greatest help for pulling up? The following mathematics, physics and biology are used to analyze and solve this sports problem. Analysis is different from inanimate objects. The movement of the human body is a movement controlled by consciousness. Therefore,