Safe Steps to Take 1/2

This month is about walking and falling. For many of us the time that walking resulted in falling is far in the past. As we age, we will all experience another time when walking and falling are associated. Do we know when that time has come?

At the Vrije Universiteit, I spoke with Nick Kluft a colleague at Human Movement Sciences. In his PhD research, he investigates whether elderly know which steps they can take without falling. In other words, whether their perceived ability is up to date with their true ability.

If errors in perceived ability contribute to falls, falls could be reduced with interventions that improve perceived ability. Here, Nick talks about his research that has recently been published in Gait and Posture.


“Simple questions on physical ability can result in very subjective and possibly incorrect answers. To measure perceived ability, I developed a method that focuses on doing. Some steps are riskier than others, for instance very wide or high steps are riskier than small steps. Therefore I designed tests that challenge participants to make risky steps.

The paper river test is a nice example. My participant stands on the wide side of a tapered river and has to cross the river as quickly as possible. Without stepping into the water off course. The width where someone crosses reveals the step size he or she dares to take: the perceived ability. To test true ability, I secure my participants in a safety harness and ask them to make steps of increasing size until they loose balance.


Four challenges to test perceived ability: a) Obstacle bar. b) Paper river test. c) Obstacle line. d) Stepping from an angle.

My research showed that perceived ability differs from true ability. The difference depended on how risky an error was. On the paper river test, most participants overestimated their ability. When I challenged them with an obstacle bar that I placed at increasing heights, the reverse seemed to happen. Participants tended to underestimate their ability.

Errors in perceived ability may contribute to falls. Some people are frequent fallers: they fall more often than average. One third of these frequent fallers cannot be explained by physical ability alone. Perhaps these cases would be explained when we take perceived ability into account.

When people have an overly positive image of their ability, they may take too many risks. With falls as a result. Being too conservative could decrease falls. However, playing it too safe reduces physical activity, which can accelerate aging.

A colleague, Roel Weijer, investigates whether errors in perceived ability contribute to falls. If that is the case, interventions could be developed that improve perceived ability.

For more information on how to participate in Nick’s research see:

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