Submaximal cardiopulmonary thresholds on a robotics-assisted tilt table, a cycle and a treadmill: a comparative analysis

Abstract

BackgroundThe robotics-assisted tilt table (RATT), including actuators for tilting and cyclical leg movement, is used for rehabilitation of severely disabled neurological patients. Following further engineering development of the system, i.e. the addition of force sensors and visual bio-feedback, patients can actively participate in exercise testing and training on the device. Peak cardiopulmonary performance parameters were previously investigated, but it also important to compare submaximal parameters with standard devices. The aim of this study was to evaluate the feasibility of the RATT for estimation of submaximal exercise thresholds by comparison with a cycle ergometer and a treadmill.Methods17 healthy subjects randomly performed six maximal individualized incremental exercise tests, with two tests on each of the three exercise modalities. The ventilatory anaerobic threshold (VAT) and respiratory compensation point (RCP) were determined from breath-by-breath data.ResultsVAT and RCP on the RATT were lower than the cycle ergometer and the treadmill: oxygen uptake (V′O2) at VAT was [mean (SD)] 1.2 (0.3), 1.5 (0.4) and 1.6 (0.5) L/min, respectively (p < 0.001); V′O2 at RCP was 1.7 (0.4), 2.3 (0.8) and 2.6 (0.9) L/min, respectively (p = 0.001). High correlations for VAT and RCP were found between the RATT vs the cycle ergometer and RATT vs the treadmill (R on the range 0.69–0.80). VAT and RCP demonstrated excellent test–retest reliability for all three devices (ICC from 0.81 to 0.98). Mean differences between the test and retest values on each device were close to zero. The ventilatory equivalent for O2 at VAT for the RATT and cycle ergometer were similar and both were higher than the treadmill. The ventilatory equivalent for CO2 at RCP was similar for all devices. Ventilatory equivalent parameters demonstrated fair-to-excellent reliability and repeatability.ConclusionsIt is feasible to use the RATT for estimation of submaximal exercise thresholds: VAT and RCP on the RATT were lower than the cycle ergometer and the treadmill, but there were high correlations between the RATT vs the cycle ergometer and vs the treadmill. Repeatability and test–retest reliability of all submaximal threshold parameters from the RATT were comparable to those of standard devices.

Ventilatory efficiency during constant-load test at lactate threshold intensity: Endurance versus resistance exercises

“…Our findings show that two types of exercise with different cardioventilatory responses induce the same ventilatory efficiency at similar metabolic intensity. During incremental exercise tests [23], no significant changes were found between treadmill and cycle ergometer trials, although both exercise modalities showed a lower VE/VCO 2 slope (higher efficiency) compared to a robotics-assisted tilt table. A study compared OUES in 17 healthy subjects in two exercise modalities, observing higher values in the treadmill test compared to the cycle ergometer [24].…”

“…Although many studies have analyzed the slope of VE/VCO 2 and OUES by age, sex, fitness level, and diseases in endurance exercises [10, 11, 14, 17, 19], it is unusual to observe studies comparing VE/VCO 2 slope and OUES between different exercise modalities [23, 24]. Sun et al [10] demonstrated that VE/VCO 2 slope is not exercise mode-dependent, however, Davis et al detected that VE/VCO 2 slope was lower on the cycle ergometer than the treadmill in women but not in men [25].…”

Test-retest reliability and four-week changes in cardiopulmonary fitness in stroke patients: evaluation using a robotics-assisted tilt table

“…For submaximal exercise thresholds, the reliability of V'O 2VAT and V'O 2RCP were lower than for V'O 2peak : ICC was 0.67 and CoV was 14.5 % for V'O 2VAT ; ICC was 0.65 and CoV was 11.6 % for V'O 2RCP . These values, again, reflect lower reliability compared to healthy individuals on the same device: the ICC was 0.92 for both V'O 2VAT and V'O 2RCP and the CoV was 5.9 and 6.5 % for V'O 2VAT and V'O 2RCP , respectively, for healthy individuals [ 18 ]. The finding of lower reliability for V'O 2VAT and V'O 2RCP compared to V'O 2peak was not unexpected as this was previously documented in healthy individuals, and in patients with cardiac and pulmonary problems [ 17 , 18 , 39 ].…”

“…The latter was calculated from the forces in the thigh cuffs and the angular velocities. Adapted from Saengsuwan et al, 2015 [ 18 ] …”

“…A previous validity and reliability study in healthy individuals found that peak oxygen uptake and submaximal exercise thresholds on the RATT were approximately 20 % lower than for a cycle ergometer [ 17 ]. Test-retest reliability of maximal and submaximal exercise thresholds on the RATT were comparable to standard exercise devices [ 17 , 18 ]. Furthermore, a feasibility study in stroke showed that patients with severe disability could successfully undergo CPET and exercise training on the RATT [ 15 ].…”