The Psychophysiology of Walking

The literature suggests that natural environments, such as those on the Belgian coast, improve several psychological and physiological health parameters. In these environments, recreational activities often involve walking. However, it is still unknown how the effects of the environment and of walking together influence health. This study investigates the effects of a walk on the Belgian coast versus in the city on various psychological and physiological parameters of mental and physical health, both while walking and at rest after walking. A second set of research questions concerns the determination of the mediating roles of the physical activity performed, the other people in the environment, and environmental factors such as weather and perceived safety. This means that the investigators need to measure how these mediators differ between both environments, and to what extent these mediators have an impact on the subjects. A third set of research questions concerns the moderating roles of the individual characteristics (e.g. age, sex, SES personality, health) on the effects.

100 healthy Belgian adult subjects have to take a walk in both environments according to a within-subject cross-over design, while measurements are taken before, during, and after the walks. Before each walk there is also a walking session on a treadmill for baseline measurements, and rest periods before and during the walk to measure responses after the physical activity with the influence of the environment. The walk on the Belgian coast will take place in Ostend on the dike between the beach and the dunes, and the walk in the city will take place in Ghent center on a similar hard surface.

A lot of physiological measurements will be done to determine the activity of the nervous systems and the HPA axis. More specifically, the heart rate will be derived from the electrocardiogram (ECG) as a general measure of the activation of the body and the high-frequency heart rate variability (HF-HRV) as a measure of the change in the activity of the parasympathetic nervous system. From a blood volume pulse signal (BVP) the mean arterial Pressure (MAP) will be derived as a general measure for the activation of the body and the blood circulation. From a skin conductance signal (EDA) the skin conductance level (SCL) and skin conductance responses (SCR) will be derived as measures of the activity of the sympathetic nervous system. From a respiration signal, respiration rate and depth will be derived as measures of regulation by the respiratory center in the brain. The average tone will be derived from the electromyogram (EMG) as a measure of musculoskeletal activation. These electrophysiological measurements will be made using sensors on the body and MindMedia's medically validated Nexus-10 MKII device. The activity of the HPA axis of stress will be measured by determining the concentration of the cortisol hormone in saliva.

In addition, many questionnaires will be administered that measure the stress level, mood, psychological tension (arousal), worrying and rumination, mindfulness-related and subjective experiences of the participants.

The investigators will closely monitor the mediating role of physical activity using a smartphone that will measure accelerometry, location and walking speed. The mediating roles of the other persons in the environment, the weather, and other environmental factors (e.g. naturalness) will be retrospectively questioned via post-walk questionnaires. It is not unimportant that many characteristics of the test subjects can respond to the effect sizes. That is why the investigators also ask for a lot of data about demographics, socio-economic status, lifestyle, health, personality, and other factors for the experiment.

The hypothesis is that as a result of the physical activity, all physiological parameters of stress will increase, because physical activity affects the same physiological pathways as those of stress. The walk on the coast would increase the psychological and physiological differently than the walk in the urban environment. According to the literature, these effects should be are mediated by physical activity, other people in the vicinity, weather, and other environmental factors (e.g. perceived naturalness).