The Gait Cycle Part 1: Basic Mechanics





The Gait cycle is the repetitive movement pattern seen in both walking and running. The pattern is similar except that running does not involve a double limb stance phase in the same way that walking does. The Gait cycle can be broke down into two main phases Stance and Swing.

Stance Phase

This is the first phase in the Gait cycle and begins when one heel strikes the ground, it finishes with toe off.

  1. Heel Strike: As simple as it sounds this is the start of the gait cycle and it begins with the heel striking the ground. It has divided opinions around the benefits of heel, mid foot and fore foot striking.
  2. Mid Stance: The period at which weight shifts from the back of the foot to the front.
  3. Toe Off: When the toe pushes off the ground to propel us forward.
The Gait Cycle

Swing Phase

  1. Acceleration: The period between toe off and maximum knee flexion
  2. Mid-Swing: Between maximum knee flexion and the tibia of the swing leg reaching a vertical position.
  3. Deceleration: Once the Tibia passes vertical it begins to decelerate until heel strike.
The Gait Cycle
During running the gait cycle varies depending on speed, fatigue, surface and terrain. During walking the Stance Phase make up 60% of the cycle and the Swing Phase 40% as speed increases and running begins the period of time covered by stance decreases.

Studies have shown that an increase in stride rate and a decrease in stride length can lead to a decreased in patellafemoral loading (Lenhart etal. 2014 and Wilson et al.2104). Over the next few articles we will take an in depth look at the biomechanics of gait and how the gait cycle affects injury risk and performance.

Each segment of the kinetic chain interacts differently at the varying stages of the gait cycle. So, what does “normal” look like.

Ankle:

The movement of the ankle changes significantly from person to person and also varies, depending on foot strike position. In normal gait we can expect that at initial contact the foot is slightly dorsiflexed approx. 10 degrees and also slightly inverted.

At mid stance ankle dorsiflexion reaches its greatest approx. 20 degrees and also is near its greatest eversion angle which varies significantly person to person.

As the foot moves towards toe off, dorsiflexion decreases and the foot plantarflexes, eversion is also decreasing and becomes inversion at 80% of stance phase.

Knee:

At the point of initial contact the knee is in a slightly flexed position approx. 10 degrees, it is very slightly abducted and also mildly externally rotated.

As we progress towards midstance, flexion increases to its maximum of 40-50%, in the frontal plane the knee slightly adducts typically 4-5% and internally rotates.

From midstance onwards towards toe off, this process is reversed knee flexion angle decreases until the knee is almost fully extended, abduction decreases and becomes adduction and the internal rotation achieved at midstance also reverses.

Hip:

At initial contact the hip is flexed at 30%, it is slightly adducted 2-5% and also possess a small internal rotation.

As stance continues flexion is maintained until 40% of the stance, from this we can see that the body relies primarily on knee flexion to bring the centre of mass down. Adduction increase as the body moves forward and only starts decreasing once hip extension begins. Whilst internal rotation peaks much earlier at approximately 20% of stance and subsequently decreases through the rest of stance.

As midstance progresses to toe off, hip flexion becomes almost full hip extension.

Coming next in the performance zone we will look at “common biomechanical issues in gait”.

Willson, J. D., Sharpee, R., Meardon, S. A., & Kernozek, T. W. (2014). Effects of step length on patellofemoral joint stress in female runners with and without patellofemoral pain. Clinical Biomechanics, 29(3), 243–247.

Lenhart, R. L., Thelen, D. G., Wille, C. M., Chumanov, E. S., & Heiderscheit, B. C. (2014). Increasing Running Step Rate Reduces Patellofemoral Joint Forces: Medicine & Science in Sports & Exercise, 46(3), 557–564.