In May 2018 researchers from the UK published the results of their study to compare the physiological and perceptual responses of running on a curved non-motorized treadmill and on a motorized treadmill. 13 male runners (average age 36 years, average weight 70 kg) first completed an initial session on a curved non-motorized treadmill followed by 5-6 sessions at increasingly higher speeds for a period of 4 minutes each. On a separate visit the individuals undertook a similar session but this time on a motorized treadmill. Results showed that running on a curved non-motorized treadmill required a higher oxygen consumption and was accompanied by a significantly higher heart rate, an altered running rhythm and a feeling of having had a harder work out than when compared to a motorized treadmill. Running economy was less efficient when using a curved non-motorized treadmill than a motorized treadmill.
Schoenmakers PPJM and Reed KE. The physiological and perceptual demands of running on a curved non-motorised treadmill: Implications for self-paced training. J Sci Med Sport. 2018 May 19. [Epub ahead of print]