In order to study whether muscle fibre type transformation, from fast to slow, could occur, studies of 1500 km ski touring along the Swedish mountain range (Fjällmarsch TranTre, in 1978; which he initiated, organized and participated in [2]) and 800 km sledge pulling in the arctic parts of Scandinavia (The 1982 Minnesota Lappland Expedition, organized by Concordia College, Minnesota, USA) were included in his doctoral thesis Plasticity of human skeletal muscle from 1986.
"[4] He had by that time already expanded his research interests into the multidisciplinary field of physical activity, public health and sustainable development.
An initial focus on issues related to outdoor life recreation in periurban green areas is mirrored in the books The National Urban Park – An Experiment in Sustainable Development (2002), The European City and Green Space (2006), Forests, Trees and Human Health (2011).,[5] and Why Large Cities Need Large Parks.
[13] His studies of the effects of outdoor external environments has led him to the conclusion that they can lower the perceived exertion compared to when given exercise is undertaken in laboratory or other indoor settings.
[14] He has also contributed to developing the heart rate method for estimating oxygen uptake to facilitate exercise physiological studies of walking and cycling.