An Analysis Of VO2 And Lower Limb Muscles' EMG Between Overground And Treadmill Running

Objective:By recording VO2 and lower limb muscles'EMG on treadmill running and overground running, expounding the relationship between this two movements, so that the treadmill test and training can better serve the athletic training, and provide scientific methods for exercises and training.Methods:8 male middle--distance runners and each runner had two days testing so as to avoid fatigue. Each subject ran 6 minutes at 10,12, 14,16,18km/h randomly on treadmill (0%,5%,10%) and track respectively, and 10 minutes interval between the two periods. Portable electromyograph (Megawin ME-6000) recorded the electrical activity of lower limbs muscles (gluteus maximus, vastus lateralis, biceps femoris, gastrocnemius medial head, and tibialis anterior muscles), and portable gas metabolic instrument (V02000) recorded the data of V02.Results:(1) The results of gas metabolism:the V02 value on overground and treadmill running increase as the speed and gradient go up; at the same running speed, V02 value of overground running is higher than the V02 value of 0% gradient of treadmill running, and approximately equal to the V02 value of 5% gradient of treadmill running, and lower than the V02 value of 10% gradient of treadmill running; treadmill and overground running velocity-V02 Prediction Equations has been buil. At the same time, treadmill running incline and velocity-V02 prediction equation also has been build. (2) The results of EMG:at the overground running, IEMG of the lower limb muscles generally show an upward tendency as running velocity increased; at the 10% gradient of treadmill running, IEMG of tibialis anterior muscle reaches a maximum at the velocity of 14km/h, then with the running velocity increased, its IEMG no longer increased; at a relatively slower treadmill running (10-14km/h), IEMG of tibialis anterior muscle increased with the gradient rised. But when the running velocity above 16km/h, its IEMG no longer increased with the gradient rised; at overground running, MPF of tibialis anterior and vastus lateralis muscles decreased gradually as running velocity increased. At treadmill running, MPF of measured lower limbs muscles has no obvious regularly changing as running velocity and gradient rised.Conclusions:V02 value of overground running is significantly higher than 0% gradient of treadmill running, and similar with 5% gradient of treadmill running, but lower than 10% gradient of treadmill running; Running at 10% gradient of treadmill, the level of V02 can be improved when the velocity at the range of 10-16km/h; At the aspect of muscle force, 0% gradient of treadmill running is different from overground running. But 5% gradient of treadmill running can simulate the overground running, and 10% gradient of treadmill running can give more stimuli to the lower limbs muscles to meet the training requirements; When running at treadmill, tibialis anterior muscle must recruit more motor units to work than at overground running. However, the increase of gradient and velocity has a marginal effect on the recruitment of motor units.