THE WALK-RUN TRANSITION IS NOT AFFECTED BY ADDED COGNITIVE LOADING

INTRODUCTION:Walk-run transition can be predicted from stride rates (1, 2), based on the assumption that the human acts as a complex system (3), which can be described with Dynamic Systems Theory (4). Besides, two research groups have investigated the hypothesis that added cognitive loading affects the walk-run transition. One of the groups confirmed the hypothesis (5) while the other rejected it (6). To clarify this, we re-tested the hypothesis in the present study.METHODS:Healthy individuals (13 men, 5 women) participated. First, two pressure-sensitive sensors were placed under the insole of the participant’s right shoe at, respectively, a position corresponding to the midpoint of the underside of the heel and at a position corresponding to the midpoint between 1st and 2nd metatarsal heads. The sensors were used for determination of stride characteristics. Then, 10-min warm up was done on a treadmill. For this, the treadmill speed was initially 1 km/h and increased by 1 km/h each min, until the final speed of 10 km/h was completed. After 4 min of rest, the reference walk-run transition test began. For this, the initial treadmill speed was 5 km/h and increased by 0.1 km/h each 10th s, until transition occurred, or a final speed of 9 km/h was reached. This was followed by 4 min of rest. Then, the dual task walk-run transition test began. This test was similar to the reference test. But, in addition to walking, the participant had to perform mental arithmetic, which added cognitive loading. The arithmetic task began with the number 911. From this, 7 were repeatedly subtracted. To increase the cognitive loading, the participant was regularly cheered to perform the arithmetic fast. Data were evaluated with paired samples t-tests. Two subjects were omitted from the evaluation since they did not transit to running in the dual task test.RESULTS:In the reference test, the speed and stride rate at the transition were 7.5±0.5 km/h and 67.0±3.1 strides/min, respectively. In the dual task test, the matching values were 7.6±0.5 km/h and 68.4±3.7 strides/min, respectively. There were no differences between the two types of tests (p>0.05).CONCLUSION:The addition of cognitive loading in a walk-run transition test with monotonous increasing walking speed did not change the speed and stride rate at the transition. We consider this finding to be consistent with the idea that the walking human acts as a self-organized dynamic system, without influence of a central control centre.REFERENCES:1) Hansen et al., Sci Rep, 2017. 2) Hansen et al., Gait Posture, 2018. 3) Soodak & Iberall, Science, 1978. 4) Luenberger, Introduction to dynamics - Theory, models and applications, 1979. 5) Daniels & Newell, Biol Psychol, 2003. 6) Abdolvahab, Atten Percept Psychophys, 2015.