title: Cardiopulmonary performance testing using a robotics-assisted tilt table: feasibility assessment in able-bodied subjects.
abstract: BACKGROUND
  Robotics-assisted tilt table technology was introduced for early rehabilitation of neurological patients. It provides cyclical stepping movement and physiological loading of the legs. The aim of the present study was to assess the feasibility of this type of device for peak cardiopulmonary performance testing using able-bodied subjects.
  
  
  METHODS
  A robotics-assisted tilt table was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Feasibility assessment focused on: (i) implementation (technical feasibility), and (ii) responsiveness (was there a measurable, high-level cardiopulmonary reaction?). For responsiveness testing, each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/min in female subjects and 8 W/min in males.
  
  
  RESULTS
  11 able-bodied subjects were included (9 male, 2 female; age 29.6 ± 7.1 years: mean ± SD). Resting oxygen uptake (O<formula>_{2}</formula>) was 4.6 ± 0.7 mL/min/kg and O<formula>_{2}</formula>peak was 32.4 ± 5.1 mL/min/kg; this mean O<formula>_{2}</formula>peak was 81.1% of the predicted peak value for cycle ergometry. Peak heart rate (HRpeak) was 177.5 ± 9.7 beats/min; all subjects reached at least 85% of their predicted HRpeak value. Respiratory exchange ratio (RER) at O<formula>_{2}</formula>peak was 1.02 ± 0.07. Peak work rate) was 61.3 ± 15.1 W. All subjects reported a Borg CR10 value for exertion and leg fatigue of 7 or more.
  
  
  CONCLUSIONS
  The robotics-assisted tilt table is deemed feasible for peak cardiopulmonary performance testing: the approach was found to be technically implementable and substantial cardiopulmonary responses were observed. Further testing in neurologically-impaired subjects is warranted.
authors.affiliation: Institute for Rehabilitation and Performance Technology, Division of Mechanical Engineering, Department of Engineering and Information Technology, Bern University of Applied Sciences, Burgdorf, Switzerland ARTORG Center for Biomedical Engineering Research, Gerontechnology and Rehabilitation Research Group, Bern University, Bern, Switzerland Department of Physical Medicine and Rehabilitation, Faculty of Medicine, Khon Kaen University, Thailand.
authors.forename: J
authors.initials: J
authors.lastname: Saengsuwan
authors.affiliation: Institute for Rehabilitation and Performance Technology, Division of Mechanical Engineering, Department of Engineering and Information Technology, Bern University of Applied Sciences, Burgdorf, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Laubacher
authors.affiliation: ARTORG Center for Biomedical Engineering Research, Gerontechnology and Rehabilitation Research Group, Bern University, Bern, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: Nef
authors.affiliation: Institute for Rehabilitation and Performance Technology, Division of Mechanical Engineering, Department of Engineering and Information Technology, Bern University of Applied Sciences, Burgdorf, Switzerland.
authors.forename: K J
authors.initials: KJ
authors.lastname: Hunt
mesh_terms: D000328:Adult; D005080:Exercise Test / Q000295:instrumentation* / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D005240:Feasibility Studies; D056228:Feedback, Sensory; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D012016:Reference Values; D012371:Robotics / Q000379:methods*; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Rehabilitation; cardiopulmonary performance testing; rehabilitation robotics; tilt table