What does ground reaction force refer to in relation to running?

Ground reaction force refers to the force that the ground exerts back on the body in response to the force applied by the runner's feet upon impact with the ground. When a runner strikes the ground, they exert a force downward, and according to Newton's third law of motion, the ground reacts by pushing back with an equal and opposite force. This reaction force plays a crucial role in understanding the biomechanics of running, including the effects on speed, energy expenditure, and injury prevention.

Understanding ground reaction force is essential for coaches and runners alike because it affects how a runner's body interacts with the ground during various phases of running. This force is not just about the weight of the runner or the impact of the shoes; it encompasses the dynamic interaction between the runner and the ground as they move.

The other choices don't capture this fundamental interaction as accurately. The force exerted by the body during a foot strike is part of the reaction but does not fully define the concept of ground reaction force itself. The total weight of the runner describes the gravitational force acting on them but not the reaction force from the ground. Lastly, while the impact of running shoes can influence the overall ground reaction forces experienced, it does not define the term itself.