Validity Of ‘Range-based Methods’ Compared To The ‘Ventilatory Thresholds-based Method’ For Exercise Intensity Prescription In Patients After Bariatric Surgery

Obesity represents an ongoing pandemic and bariatric surgery is needed in severe, morbid obesity. Sustainable weight loss and positive effects on cardiometabolic conditions can thereby be achieved, while concomitant exercise training positively affects body composition, weight regain, muscle strength and fitness. Cardiopulmonary exercise testing (CPET) is the gold standard methodology for exercise prescription (ExRx), defining intensities based on ventilatory thresholds (VTs). However, ExRx by range-based methods may be a more affordable option for such a large population. PURPOSE: to determine the validity of range-based methods versus VTs-based methods for exercise intensity prescription of endurance training in patients after bariatric surgery. METHODS: 565 patients were evaluated 6-month after bariatric surgery by CPET. VT1 and VT2 were considered as lower limits of the moderate and high intensity domain, respectively. Values of oxygen consumption (VO2) and heart rate (HR) obtained at VT1 and VT2 were compared with the respective lower limit of moderate and high intensity ranges, determined by the percentages of measured and predicted values of peak VO2 (VO2 peak), maximum HR (HRmax) and Karvonen HR (HRKarv), as proposed by the 2020 ESC Guidelines. RESULTS: all values of VO2 and HR at the lower limit of both moderate and high intensity according to the 2020 ESC Guidelines, were statistically significant different from the respective values at VT1 and VT2. All range-based methods seem to underestimate exercise intensity, while the predicted HRKarv leads to overestimations. Overall, the HRKarv relying on measured HRrest and HRmax appears more closely related to the HR at VT1 and VT2. CONCLUSION: in patients after bariatric surgery, range-based methods as proposed by 2020 ESC Guidelines are not valid enough to provide adequate ExRx; the identification of VTs by CPET remains essential. Measured HRKarv is the most appropriate alternative for this population. - CPET dataVT1 1 Lower limit of “moderate” intensity 2, 3 Spearman’s rank correlation CPET dataVT2 1 Lower limit of “high” intensity 2,3 Spearman’s rank correlation VO2 [mL/kg·min]13.0 (11.3, 14.9) Measured 40% VO2 peak [mL/kg·min]8.8 (7.5, 10.2) *** 0.756 *** VO2 [mL/kg·min]17.3 (14.9, 19.7) Measured 70% VO2 peak [mL/kg·min]15.4 (13.1, 17.9) *** 0.901 *** HR [bpm]110 (99, 119) Measured 55% HRmax [bpm]84 (77, 91) *** 0.646 *** HR [bpm]133 (120, 146) Measured 75% HRmax [bpm]115 (105, 125) *** 0.790 *** Predicted 55% HRmax [bpm]95 (91, 98) *** 0.424 *** Predicted 75% HRmax [bpm]130 (125, 134) * 0.543 *** Measured 40% HRKarv: HR rest + 40% HRreserve [bpm]107 (99, 115) ** 0.768 *** Measured 70% HRKarv: HR rest + 70% HRreserve [bpm]130 (119, 140) * 0.819 *** Predicted 40% HRKarv: HR rest + 40% HRreserve [bpm]115 (110, 121) *** 0.663 *** Predicted 70% HRKarv: HR rest + 70% HRreserve [bpm]144 (138, 150) *** 0.640 ***