Supervised exercise training programmes in bariatric surgery candidates: effects and impact on health

Abstract

BACKGROUND: Bariatric surgery (BS) is considered the most effective treatment for morbid obesity, whose global prevalence has been increasing in recent decades. However, its clinical approach is carried out through multimodal treatment, combining pharmacological therapies with interventions aimed at stimulating lifestyle changes at three levels: nutritional, behavioural, and physical activity practice. Typically, when lifestyle interventions do not achieve the targeted weight loss within a six-month period, the patient is considered for BS if they have a Body Mass Index (BMI) 40 kg·m-2, or a BMI 35 kg·m-2 with associated comorbidities (e.g., metabolic syndrome). However, study results in patients undergoing BS techniques have shown that the weight prior to surgery is regained in the medium and long term in many cases, causing health problems and negatively affecting the self-esteem of those treated. In the short term, one of the most highlighted problems is the loss of fat-free mass (FFM) following the surgical intervention, whose prevention strategies are still being studied from both a nutritional and physical exercise perspective, specifically strength training. There is significant evidence about the benefits of physical activity in the form of regular physical exercise on individual health, whether it is aerobic or strength exercise, in the obese population due to its positive impact on weight loss and cardiometabolic health. However, issues such as its feasibility or safety in cases of morbid obesity remain unsolved. Similarly, while most previous studies in BS patients have been conducted post-surgery, evidence on the effects of pre-surgical weight loss intervention programs is scarce. In this regard, considering that the main goal of BS is weight loss and consequent improvement in cardiometabolic health, and that regular physical exercise has been widely demonstrated to be useful in achieving this goal, it is logical to question why physical activity programmes (PAPs), structured and monitored, are not carried out both in preparation and in post-surgical follow-up of patients with morbid obesity in the clinical setting. Additionally, the results of previous studies on the effects of exercise-based interventions in this population are not conclusive, demanding further research in this area. Therefore, the main objectives of this doctoral thesis were: 1) to study the impact of physical activity programs (PAPs) conducted in bariatric patients, both in preparation and in post-surgery follow-up, on health; and 2) to explore the effects of different exercise-based training programs (ETPs) in patients awaiting BS.

METHODS: To address the objectives set out in this Doctoral Thesis, both review methods and experimental methods were used. On one hand, in study 1, review methods were employed, involving electronic searches in two different databases. On the other hand, in studies 2 and 3, experimental methods were used. Patients, referred from the hospital as they were awaiting BS, voluntarily contacted and underwent an anamnesis to ensure the absence of exclusion criteria: asthma, obstructive pulmonary disease, cardiovascular disease, hypothyroidism, or functional limitations for carrying out a PAP. They were assigned to either an experimental group or a control group based on their individual availability to regularly attend training sessions. All participants were assessed at the beginning and end of the intervention: specifically, at three and six months in studies 2 and 3, respectively. Anthropometric parameters and cardiorespiratory fitness were recorded in both studies, in addition to muscular strength measurements in study 2 and substrate oxidation at rest in study 3. In both interventions, participants in the experimental group underwent an ETP where the weekly sessions progressed monthly up to the third month in both studies, maintaining four weekly sessions until the end of the intervention in study 2. Furthermore, while in study 2, high-intensity interval training (HIIT) sessions combined with resistance training at high loads were alternated with moderate-intensity continuous training (MICT) sessions, in study 3, aerobic training sessions at the intensity of maximum fat oxidation (Fatmax) were alternated with resistance training sessions at low loads. Comparisons between the groups were reported as the mean difference with a 95% confidence interval, along with its practical significance reported with effect size values.

RESULTS: Study 1, a review, demonstrated heterogeneity among various studies conducted on patients both awaiting and having undergone BS, in aspects such as study design, sample characteristics, or components of the PAP, among others. However, the findings indicated that the role of PAPs had been studied to a greater extent post-BS than in the months prior to the surgical intervention. Moreover, it was observed that despite recommendations for physical activity practice prior to surgery, the effects derived from PAPs required further research for several reasons: 1) neither the measurement instruments nor the applied protocols were standardized; and 2) there was discrepancy regarding the most appropriate time to introduce a PAP in BS patients. Consequently, in the first experimental study (study 2), significant changes were registered in BMI, as well as positive changes in body composition, cardiometabolic health, and cardiorespiratory fitness. Reductions in visceral fat (VF) and fat mass (FM) were observed both in absolute values (kg) and relative to total body weight (%), accompanied by the maintenance of FFM in the experimental group. In addition, a high participation rate (> 90% of all supervised training sessions) was registered. Finally, in the second experimental study (study 3), no significant changes in body composition were shown, but the maximal fat oxidation (MFO) registered during exercise increased, remaining constant at rest. Similarly, the resting metabolic rate (RMR) did not change in participants of the experimental group.

CONCLUSIONS: Preoperative interventions with structured and monitored ETPs appear to be viable and safe for adults with obesity awaiting bariatric surgery, with no incidents registered. Regarding the type of training, combining HIIT with resistance training at high loads seems to potentially provide positive changes in body composition, particularly in VF. Furthermore, values of MFO seem to improve regardless of changes in body composition, which may be highly relevant in the treatment of comorbidities associated with obesity. The results of this Doctoral Thesis demonstrate the feasibility of conducting an ETP in patients awaiting BS, as well as the importance of standardizing and monitoring both the assessment tests and the prescription and control of the ETPs, contributing two aspects: 1) greater safety in practice; and 2) greater reproducibility of experimental designs in future research where similar ETP interventions are applied to confirm the obtained results.