The assessment of exercise intensities for tailored exercise prescription in patients with obesity after bariatric surgery
Authors: Quinto G , Centanini A , Faggian S , Battista F , Vecchiato M , Gasperetti A , Neunhaeuserer D , Ermolao A 
Published: June 2024

Abstract

Background
Tailored exercise prescription is an integral part of obesity therapy, and determining the appropriate exercise intensity (EI) is crucial to optimize its beneficial effects, especially after bariatric surgery (1). The gold standard for assessing and thus prescribing EI is to use ventilatory thresholds measured during cardiopulmonary exercise testing (CPET), but this test is expensive and often unavailable (2). Different indirect formulae have been proposed, for range-based prescriptions based on percentage of peak of oxygen consumption (VO2), maximal heart rate (HRmax) or Karvonen HR (HRKarv) (3).

Purpose
The aim of this study is to verify if the indirect, "range-based" prescription methods as proposed by the 2020 European Society of Cardiology (ESC) guidelines on exercise in patients with cardiovascular disease are also appropriate for prescribing exercise intensity in patients after bariatric surgery (4).

Methods
565 patients were evaluated 6-months after bariatric surgery by CPET. The percentages of peak oxygen consumption (%VO2 peak test), maximum heart rate (%HRmax; measured and calculated) and Karvonen heart rate (%HRKarv; measured and calculated), obtained at the first ventilatory threshold (VT1) and second ventilatory threshold (VT2), were compared with the respective EI domains proposed by ESC guidelines with sensitivity analyses, considering the moderate exercise intensity range at VT1 and high exercise intensity range at VT2.

Results
Results are showed in Table I, also differentiate by body mass index reached after bariatric surgery. Comprehensively, the method with the highest sensitivity at both EI domains was %VO2 peak test. With this method, 16% (at VT1) and 37% (at VT2) of patients do not fit into an EI range corresponding to "moderate" and "high" intensity domains, respectively. Focuses on subgroup analyses in moderate EI domain, %VO2 peak test method reaches 90% sensitivity in normal-weight patients subgroup. In high EI domain, absolute values of sensitivity are averagely lower, varying from 59% to 71% in different subgroups.

Conclusions
Sensitivity analyses of relative method values, at VT1 and VT2, demonstrate that a non-clinically negligible and highly variable percentage of patients after bariatric surgery fit into an EI not corresponding to "moderate" and "high" intensity domains, respectively, as defined by 2020 ESC guidelines. In patients after bariatric surgery, the identification of ventilatory thresholds by CPET remains essential for determining correct EI domains.
Table I. Sensitivity (IC 95%) of relative methods for determining "moderate" and "high" exercise intensity domains.
*p&lt;0.05 when compared with best method for specific EI domain in the same population.
VO2, oxygen consumption; HRmax, maximal heart rate; HRkarv, Karvonen heart rate; N, normal-weight patients; O, overweight patients; I, obesity class I; II, obesity class II; III, obesity class III. Table I