In November 2017 researchers from Australia published the results of their study to compare the cardiometabolic demands of running on a curved non-motorized treadmill with overground and motorized treadmill running. Fourteen trained runners (7 male, 7 female) participated in the study. Each session consisted of 5 × 6-minute sessions of running at progressively higher speeds, separated by a 6-minute rest. Oxygen consumption and heart rate were measured during the last 2 minutes of each session. Results showed that a higher cardiometabolic demand was required when running on the curved non-motorized treadmill. Similarly, heart rate during the session on the curved non-motorized treadmill was higher when compared to running on an overground or motorized treadmill. The decline in running economy observed during the curved non-motorized treadmill session was related to body mass, as lighter runners had to work at a higher intensity to overcome treadmill belt resistance.
Edwards RB et al. Non-motorized Treadmill Running Is Associated with Higher Cardiometabolic Demands Compared with Overground and Motorized Treadmill Running. Front Physiol. 2017 Nov 14;8:914