Updated by Rosie Edwards
“Just put one foot in front of the other! “ Seems easy enough, but how does your stride really work? Understanding how you run can help you to understand what stresses and strengths your body has as it covers ground day after day.
Running is differentiated by the instant where both feet are concurrently airborne, as opposed to walking, which always includes one foot on the ground. Some describe the running stride in two phases, support and swing, while others divide the stride into three stages[i] four stages[ii], two stages with multiple stages within these larger divisions[iii], five stages[iv], and more.
Regardless of how the stride is divided, many of the ways in which the stride is discussed cover similar ground. Like the chicken and the egg, as the first one ends, the next one starts, although some have strong feelings regarding whether or not the stride should technically begin at toe-off or while the foot is in the air[v]. For our purposes, we’ll begin with the lead foot about to return to the ground, the hamstring and gluteus contracting and preparing to absorb the coming contact with the ground. Watching an athlete running on a treadmill helps to more clearly visualize this aspect of the stride. The leg anticipates pulling the body past the ground underneath and the large muscle groups on the back of the leg in particular help to initiate this pulling motion as the lead foot heads toward the ground.
Once the foot hits the ground, the body absorbs the initial contact (whether heel, midfoot, or forefoot), with a bending leg and a collapsing foot (pronation), as the muscles contract to control the joints and effect of the shock caused by gravitational forces[vi]. If bouncing on a trampoline, the trampoline can provide the absorption and return forces needed to propel oneself up again. In other words, one can bounce on a trampoline with straight legs as the leg muscles aren’t required to contract and extend to return the body to the air. On the solid ground, the legs must provide the absorption and propulsion. This requires them to bend and give.
Next, the weight of the body travels forward in preparation for the toe-off from the forefoot. This response is not unlike a rubber band or a spring. The joints and ligaments of the foot flex and contract to allow transition from the initial landing point on the foot, to a point where the foot is absorbing maximum downward stress, to the toe-off where the hip flexor is extended and the opposite knee is flowing forward and up.
When the foot leaves the ground, it cycles underneath the body, and follows the knee forward and downward to ideally land underneath the body to efficiently recreate the cycle again. As speed increases, the amount of time spent during this portion of the stride increases and the reciprocal percentage of the time during the stride spent on the ground decreases. The dynamics of this portion of the stride vary widely, depending on hip flexor flexibility and strength, naturally occurring angles of the body, length of our legs relative to our overall height, and current speed.
As with all parts of the stride, each runner brings their own physiological idiosyncrasies to the table. However, each of our strides, rather than a forgettable, automatic process not worth a second thought, is rather an amazing series of actions and reactions that we demand from our bodies thousands of times in a row in even one run. There is debate about how much we can change our strides to resemble those of the Olympians on TV, or even the winner of last weekend’s 5K. Each of us, however, have the opportunity to increase the chances we can continue to stride as our best version of ourselves, by being mindful to strengthening and balance exercises in our legs from foot to hip, and by seeking to increase flexibility and avoid prolonged muscle tightness. Even if your stride isn’t perfect, these steps can help you resist and postpone fatigue, and stay healthy enough to continue training your legs to move you to the finish line as best they know how.
[i] Dugan, S. and Bhat, K. (2011). “Biomechanics and Analysis of Running Gait” Physical Medicine and Rehabilitation Clinics of North America http://demotu.org/pralados60/files/2011/05/DuganPMRCNA05running.pdf : p 612 Retrieved August 6, 2013
[ii] Parker, Ron. “ The Running Stride” http://www.trackandfieldcoach.ca/the%20running%20stride%20with%20photos.pdf Retrieved August 6, 2013
[iii] Phillips, Matt. “Introduction to Running Biomechanics” http://runnersconnect.net/running-injury-prevention/running-biomechanics/ Retrieved August 6, 2013
[iv] Barreau, Matthew. “The Five P’s of Running Form” http://www.brianmac.co.uk/runform.htm
[v] Novachek, Tom. (1997) “The Biomechanics of Running” Gait and Posture, Vol. 7. http://www.elitetrack.com/article_files/biomechanicsofrunning.pdf p79-80 Retrieved August 7, 2013
[vi] Dugan and Bhat: p. 609