During our everyday activities we often encounter single or multiple steps of different heights, depths and evenness.
For healthy individuals with good mobility steps and stairs do not pose a challenge. However, for people with poor fitness levels, poor balance, weakness and restricted movement of the lower limbs, steps and stairs can hamper everyday function and be a barrier to participation
When a functional task requires all out effort and attention, an environment that is very busy with many people moving in different directions and even jostling each other may increase the task demands to the point where the individual is not able to perform the task.
Steps and stairs in context
Observation in the community
1 Think about and make a note of the many times you encounter steps and stairs in your daily life.
2 Take a walk out of doors and notice the steps, including curbs, and stairs you encounter. How does the height of the step (riser) relate to the height of the individual, especially children?
3 Take time to stand and watch people going up and down a flight stairs at the station, and especially in rush hour.
4 Take time to watch people getting into a bus or minibus – these often have a big step and people may be carrying a bag of shopping.
Visual information for steps and stairs
In most cases we negotiate steps on the fly – in other words stepping up is preceded by several approach steps, one foot is planted just before the step and the other foot is lifted up onto the step without a break in the rhythm of walking.
In order to do this smoothly, we look ahead and note the distance from our present position to the step, as well as the height of the step.
The movement brain uses the distance information to adapt the length of the footsteps taken as the curb is approached so that one foot can be planted close to, but not too close to the edge of the step.
The information about the height of the step is directly translated into the range of hip and knee movement needed to lift the foot high enough to clear the step.
Knowing the height of a step also provides information about the amount of muscular effort that will be needed mount a step.
Analysis stepping up - no approach
This action has several phases with each LL involved in a stance and a swing phase. The stepping up action can be described in terms of a leading and trailing LL.
The individual stands facing the step.
Visual information gathering about the position and height of the step.
This usually requires quick glance down using peripheral vision.
Weight transference onto the trialing LL.
The COP moves laterally and slightly backwards in anticipation of the forwards movement of the leading leg.
Stiffening of the trailing LL to accommodate the full weight of the body.
Swing phase – leading LL is lifted up onto the step
Once all the weight has been transferred to the trailing LL, the hip and knee of the leading LL are flexed to lift the foot onto the step
This movement is initiated by heel-off of the swing LL.
The combination of movements at the hip, knee and ankle are adjusted relative to one another to allow the foot to clear the step.
Note the range of flexion of the knee and ankle dorsiflexion needed to clear the step.
Once the foot is lifted clear of the step, the knee is extended to move the foot over the step.
The stance phase
The foot is lowered to the step (planted) and body weight is transferred forwards onto the leading LL.
A rapid isometric contraction of the hip and knee extensors is needed to support the initial transfer of weight over the leading LL.
This is followed by extension of the hip and knee as the body is lifted upwards.
At the same time the trailing foot is lifted up and forwards.
Adequate flexion of the hip and knee and dorsiflexion of the ankle is needed to clear the foot.
The foot of the trailing LL is lowered onto the step and lateral shift of the CoM redistributes weight over both feet.
Approach and step up - single step
In this video I take one or more steps as I approach the step. Notice the way in which the actions of the two LLs are carefully coordinated and allow for a smooth transition from swing to stance phase.
Approach and step up - 2 steps
In this video you see me stepping up two steps. The trailing LL becomes the leading limb as it is lifted up past the first step. Notice the combination of movements of the hip and knee that are needed to move the foot from behind the line of gravity (LOG) to in front of it as the foot is lifted up and forwards.
The continuous upwards and forwards movement of the COM creates momentum that needs to be accommodated and controlled.
Approach and step up - high step
In this video you see me stepping up onto a 40 cm high step. Notice how I flex and then extend the knee of my trailing LL to provide the extra power and momentum needed to lift the COM up and forwards.