1, relative motion contrast

When running on the treadmill, the running belt rolls at a certain speed. Compared with the treadmill, the runner is relatively static in the front and back direction and the left and right direction, while the body center of gravity produces a certain movement track in the vertical direction. When running on land, the ground is in a relatively static state (the rotation and revolution of the earth are ignored for the time being here), and the center of gravity of the runner's body has obvious motion trajectories relative to the ground in the front and back direction, the left and right direction and the vertical direction.

2. Air quality comparison

Running on the treadmill is carried out indoors, which requires high indoor air circulation. At present, the ventilation effect of many gyms is really worrying (think about it, there are still many gyms built underground). When the outdoor air quality reaches a certain index, outdoor land running can undoubtedly breathe fresh air better. In air quality comparison, land running is better than treadmill running.

3. Comparison of security issues:

The structure of the treadmill is that there is a rolling running belt on a completely shock-absorbing board, so it is better for knees than hard ground.

4. Comfort comparison:

The treadmill is indoors. Although you can't see the outdoor scenery, you can watch TV and listen to music. There are other factors, such as wind resistance, road conditions and weather outside. If it rains or encounters strong winds, you can only choose a treadmill.