Energy Expenditure While Walking on a Non-Motorized Treadmill

Abstract

Historically, non-motorized treadmills have been very large and required the stabilization of participants by either holding onto surrounding objects or wearing a harness during exercise sessions. Recently, smaller curved non-motorized treadmills have become available and are now being utilized in fitness centers. PURPOSE: To determine the physiological responses to walking on a curved non-motorized treadmill and to compare these responses to those of walking on a motorized treadmill. METHODS: Physically active, healthy college students (n = 11, males = 6, females = 5) walked on the motorized (MT) and a curved non-motorized (CT) treadmills at 2.4, 4.0 and 5.6 km · hour−1. Each exercise bout lasted for 6 minutes. A 10 minute rest period occurred between exercises on each treadmill and all exercise bouts occurred on the same day. The order of use for the treadmills was randomized. All subjects had experience on both treadmills prior to any testing being performed. Heart rate (HR), oxygen uptake variables (V̇o2, VE, RR, RER), muscle oxygenation (StO2) and ratings of perceived exertion (RPE) during the last minute of each exercise bout were used for analysis. A two-way ANOVA with repeated measures was performed, followed by dependent t-tests where appropriate (*P<0.05). RESULTS: Oxygen uptake variables and HR were all significantly greater for the CT than for the MT (see table below). The RPE and StO2 variables followed this trend, though not all of the differences were significant (table values in mean ± SD). DISCUSSION: All subjects easily performed all speeds on the CT without the assistance of a harness or holding on. All speeds were easily walked, except the CT5.6, which resulted in a very fast walk that bordered on jogging. The increased physical effort, as indicated by higher V̇o2 and HR values, while walking on the CT is probably due to the greater friction and/or increased muscle activation inherent with the use of a non-motorized treadmill. The results indicate that for those individuals who cannot attain desired increases in exercise intensity through jogging or running, significantly increased energy expenditure at the same speed and perceived exertion can occur while walking on the CT. PRACTICAL APPLICATION: The increased energy expenditure at each of the given walking speeds on the CT could have dramatic implications for populations that cannot achieve running speeds. For individuals whom are overweight, diseased or returning from injury, walking on the CT could allow the attainment of HR values similar to those achieved during running. The current study utilized a healthy, active population, but the results should be applicable to the aforementioned populations that cannot generally maintain running speeds for desired durations.