The purpose of this study was to evaluate the intermodal reliability of perceptually-based exercise intensity among four machines: Treadmill (TM), Stationary cycle (CB), Body Trec elliptical arm/leg (BT), and AirDyne (AD). Nineteen subjects (8 male and 11 female; age 44 + 12 yrs) completed one GXT on each of the machines, following a mode-specific protocol. Subjects also completed two 15 minute production trials (PTs) on each machine at self-selected workrates corresponding to target RPEs of 11-12 (L) and 15-16 (H). In the PTs, workloads were self-adjusted through the first 5 minutes and then remained stable for the rest of the trial. Modes were randomly assigned, and subjects were blinded to the workload throughout each trial. Heart rate (HR) and oxygen uptake (V02) were obtained during the final 5 min. of each trial using a Polar HR monitor and Aerosport TEEM 100. Also, blood lactate (BLC) was sampled immediately following exercise at each intensity. Intermodal reliability was assessed using ANOVA, intraclass correlations (R), coefficients of variation (CV), and mean absolute differences for HR, V02, and BLC during the second PT. ANOVA revealed nointeraction for BLC at either the LOW or HIGH. Post -hoc analysis showed the TM and/or BT to produce significantly higher physiological responses at both intensity levels. At the L and H, intermodal Rs were: HR (.84/.88), VO2 (8/.77) and BLC (0.09/0.67). Significant intrasubject differences were observed at the L for HR (11-47bpm, VO2 (.04-1.46 L/min), and BLC (.29-12.94 mM/L). The H trials followed a very similar trend. Using a HR criteria of +2 beats/15 sec. to assess intrasubject reliability, 0% of the subjects were reliable at both the L and H. This data suggests that perceptually-based exercise across multiple modes is associated with significant intraindividual variability, and reliability is dependent upon the statistical design and physiological variable being used. In conclusion, it is recommended that extensive exercise testing be performed to ensure that individual participants can reliably use the RPE scale, prior to using an RPE value to prescribe the intensity of exercise. / School of Physical Education

This study examined the often contrived advertising claims of the manufacturers of variable resistance isotonic machinery. Specifically, the study sought to ascertain whether certain equipment was compatible with musculo-skeletal and perceptual needs and limitations of the human user: that is, to determine whether presently installed eccentric cams, which provide the variable resistance, matched the users force curves. The format of this research was in the ergonomic tradition in which empirical research is not necessarily the primary avenue. Consequently the inter-disciplinary nature of ergonomics required small-scale laboratory- simulation experiments to be conducted in a diverse range of disciplines such as physiology, psychology and biomechanics. It was found that on all five pieces of variable resistance machinery analysed, a mismatch between the force curves and the eccentric cams exist. The cams were redesigned accordingly. The metabolic cost of performing fixed-rate isoinertial lifts was moderate. The psychophysical analysis revealed that perceptual responses indicated that the work was classified as 'light' and only at 30% stress levels do local cues begin to dominate. Based on these findings it was concluded that manufacturers advertising claims in the instances analysed were not well-founded and that variable resistance isotonic machinery should only be used to develop muscular strength and endurance, and do not effectively serve as weight-loss devices.