Stairs

Inhabiting a sphere mostly covered by water makes prime real estate something of an issue. One method we have utilized to address this constraint is adding additional stories to our structures. Initially, we transitioned between levels using ladders, utilizing the biomechanical attributes our ancestors evolved to navigate the forest canopy. At some point we invented stairs. Since then it has been a common observation that we have more control going upstairs than down.

This has to do with the mechanics of the foot and leg. When going up, we can position the ball of the foot on each step, while going down we connect with the heel. It is also easier to see where to place the foot going up and we have much better access to the shock absorption mechanisms within the foot and leg. Poor visibility and limited control make going down flights of stairs significantly more hazardous and wearing on the body than going up.1 The same applies to ladders, so going down a ladder facing away from the rungs is not recommended as you do not have the same access to control your footing at the heel.

Dream Analysis:
There is something energetically unsupportive about descending stairs. In dream analysis, going down flights of stairs within a dream is interpreted as going the wrong way…

The shock absorption mechanism of the Leg:
In going up a flight of stairs, the foot is positioned so that the ball of the foot can manage body weight with a bent knee. When going down, the ball of the foot on most stairs does not have good purchase2, and weight which could be >1.5X body weight, is managed by an extended straight leg and the heel of the foot. This results in much higher shock loads (~4X) with the resulting wear on the body. Decelerating (braking) is much more challenging to control than accelerating as we move up the flight. A common report for people with knee or hip pain is that they can go up flights of stairs easily, but struggle going down due to the increased shock loads.3

Acceleration Data:
In the table below acceleration data in the vertical axis while traversing stairs in both directions is captured and processed.

  • The max acceleration was a little surprising until it was realized that going up is pushing against gravity (1g). Going up was pushing up 1.7X the body weight. Going down is less than 1g, essentially weightless with a 1.3g end stop. Therefore the acceleration going down is nearly 2X that going up.
  • The Jerk values are significant as they represent shock loads (rate of change in acceleration). There is 4X the shock going down than going up.
  • The power spectra median frequency infers that the frequency of the shock load energy is evenly distributed up to the Nyquist frequency (25 Hz for these samples). It appears irrelevant to stair climbing but is significant in other gait patterns4.

Recommendations:

  • If you are experiencing significant joint pain from inflammation or injury recovery, take the stairs up but use an elevator to go down if available – slow and steady. If possible, don’t use the handrail going up, however, if helpful, use it to go down (it can help attenuate shock loads).
  • If you struggle to descend a flight of stairs, perhaps while healing a leg issue, try facing and holding onto the handrail. This permits the engagement of the ball of the foot within the width of the step. This is also why using a walker is better than a cane – it provides better access to the forefoot (ball) gait mechanisms5. It can also help to rotate the pelvis so that it is nearly perpendicular to the extended foot, and then rotate the other way for the next step – keeping the knee aligned with the big toe.

STAIR STRETCH EXERCISE
An exercise to strengthen and activate the lower leg and foot:

  1. In bare feet (not socks), hold onto the handrail.
  2. Hang the feet over the edge of a stair at the bottom of a staircase.
  3. Hook the edge of the stair behind the inside of the ball of the foot where the arch starts.
  4. Let both feet hang for about 15 seconds.
  5. Slightly elevate the heels about 1/2 inch.
  6. Hold for about 15 seconds.
  7. Repeat a few times.
  8. You should notice that with each cycle the heels drop further. You are loosening up the individual muscles that collectively operate the foot.
  9. There are many variants of this exercise – be creative!

FOOTNOTES

  1. I could not find data on the ratio of injuries ascending vs. descending stairs. This would be an interesting study to undertake as over a million people are injured on stairs in the US annually (House Grail). My guess is it would be > 10/1. ↩︎
  2. Stairs can be designed with a shallower depth and a wide enough tread for the entire foot to make contact. However, this is a real estate issue where the stairs take up more interior space and doesn’t address the inability of an extended leg to absorb shock loads. Stairs are a foundational unresolved ergonomics issue embedded in our built surroundings. ↩︎
  3. If you are installing a chair lift for a stairwell, buy one that you can remotely summon, so you can climb your flight of stairs, but take the lift down. This may be seemingly counterintuitive. ↩︎
  4. A COMPREHENSIVE DESCRIPTION OF GAIT ↩︎
  5. Here is a post discussing Forefoot Gait: HOW TO MOVE ↩︎