Biomecanica Del Running

T he Anatomy and
Biomechanics of Running
Terry L. Nicola, MD, MSa,b,c,*, David J. Jewison, MDd

KEYWORDS
• Running • Biomechanics • Gait cycle • Running injuries

The study of the biomechanics of running refers to understanding the structure,
function, and capability of the lower extremities and overall kinetic chain that allow a
human to run. Although no two individuals share identicalanatomy, strength, or
proprioceptive qualities, there are many similarities to understand regarding the role
of each individual’s running cycle to diagnose and treat injuries that occur from
running. This article discusses the anatomy of the lower extremity as it relates to the
ability to run, the running gait cycle, and abnormal anatomy and biomechanics related
to running injuries.
RUNNINGGAIT CYCLE

The running gait cycle is different from the walking gait cycle. The gait cycle can be
described as the series of movements of the lower extremities between foot initial
impact with the surface until it reconnects with the surface at the end of the cycle.1
To better understand the gait cycle, we examine the walking gait cycle and its
differences from the running gait cycle. Thereare 2 main phases of the gait cycle, the
stance phase and the swing phase.1–3,4 The stance phase occurs during the period
of contact between the foot and the running or walking surface. These phases occur
in both walking and running. When one lower extremity is in the stance phase, the
other is in the swing phase (Figs. 1–3).
Running is distinct from walking because of an additional floatphase, which occurs
twice during running. This float phase occurs between stance phase and the swing
phase, where both lower extremities are not in contact with the ground.1 Therefore,
running at any speed can be defined as either 1 leg or no leg striking the ground
throughout the gait cycle. During the walking cycle, there is a period of double stance

The authors have nothing to disclose.
aUIC Sports Medicine Center, 839 West Roosevelt Avenue, Suite #102, Chicago, IL 60608, USA
b
Department of Orthopedic Surgery, University of Illinois at Chicago, Chicago, IL, USA
c
Family Medicine Department, University of Illinois at Chicago, Chicago, IL, USA
d
MacNeal Sports Medicine, 125 East 13th Street 615, Chicago, IL 60605, USA
* Corresponding author. UIC Sports Medicine Center, 839West Roosevelt Avenue, Suite #102,
Chicago, IL 60608.
E-mail address: tnicola@uic.edu
Clin Sports Med 31 (2012) 187–201
doi:10.1016/j.csm.2011.10.001
sportsmed.theclinics.com
0278-5919/12/$ – see front matter © 2012 Elsevier Inc. All rights reserved.

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Nicola & Jewison

Fig. 1. Swing and stance phases of running. Right leg in stance phase, left leg in swing phase.

phase duringthe walking gait cycle in which both lower extremities are in contact with
the walking surface.2 This occurs for walking at the very beginning and very end of the
stance phase. This means that during walking, 1 or 2 legs are always in contact with
the ground during stance phase.1 For walking, stance phase occurs typically for
about 60% of the gait cycle, and swing phase occurs for about 40% ofthe cycle.1,2
For walking, stance phase occurs in greater than 50% of the cycle, with swing phase
consisting of the rest of the cycle.3 The opposite is true for running, in which stance
phase is less than 50% of the cycle.2,5 This swing phase for greater than 50% of
the cycle causes an overlap of swing phases between lower extremities, generating
the characteristic float phase. As velocity inrunning increases, stance phase
becomes even less of a percentage of the cycle.2 Therefore, sprinters spend a smaller
percentage of the gait cycle in stance phase. Additionally, step length and cadence
are increased during running compared to walking.2,5 Stride length is the distance
from initial contact of 1 foot until the same foot makes contact with the running
surface again. Step length...