How to minimise bopping up and down when running
The old maxim ‘what goes up must come down’ certainly holds true in running. The higher the body launches into the air at push off, the harder, and with greater impact, the runner’s landing will be, resulting in a ground reaction force of 2-3 times the body weight. The harder the landing, the greater the chance of developing an injury.
Greater crashing on landing results in greater loads on the runner’s body and heightens the chance of injury
With too much ‘bopping up and down’, the runner’s body gains excessive amplitude (height) during each stride.Bopping up and down while running is connected to overstriding, with greater bopping movements created by an overstriding running technique.
When a runner is overstriding with a cadence of fewer than 90 single steps per minute per foot, their foot will likely land out in front of their knee and their body’s centre of mass at the time of impact with the ground. When this happens, the ground applies an equal and opposite force back up the runner’s leg. This equal and opposite ground reaction force is akin to literally putting the ‘brakes’ on as a runner. Therefore such equal and opposite ground reaction forces may be referred to as ‘braking forces’.
When a runner overstrides and encounters braking forces with every stride (see following figure), the runner must exert extra energy to overcome these forces. To do so, the body must get ‘up and over’ the foot as it lands, which requires the body to move higher into the air. This results in the up and down bopping motion observed in the overstriding runner.