Literature Research
In the initial search, 356 studies were found, 57 in Pubmed, 140 in Scopus, 106 in Web of Science, and 23 in Ebsco, where the exclusion criteria were applied. After removing the excluded studies, 20 possibly relevant studies remained, with 12 excluded after analysis of the full texts. Eight studies were collected and analyzed, as can be seen in the diagram in Fig. 1. Summarizing the research, by adapting the PRISMA-P diagram:
******** insert Fig. 1 - Diagram of the study selection process for the systematic literature review
Main Results
******** insert Table 2 - Main results obtained
******** insert Table 3 - Main characteristics of interventions
******** insert Table 4 - Evaluation variables and effects of different types of exercise
Analysis of the quality of studies
****** insert Table 5 - Results of the analysis of the quality of studies - Controlled intervention studies
Types of Studies
All studies are experimental studies, six randomized controlled trials (RCT), a quasi-experimental, and a pilot study. In six of the studies, there was an intervention group and a control group, with a study considering two intervention groups and a control group 31 and in the pilot study there were two intervention groups with different types of exercise 32.
In all of them, there was the objective of evaluating the repercussions of structured physical exercise on body composition, with aerobic, combined, or resistance exercise. The pilot study evaluated two types of exercise, aerobic and aerobic combined with resistance, in the repercussions and short-term effects on functional capacity and body composition. These exercise programs were not applied face-to-face, but programs carried out at home, with self-registration and monitoring 32. Also, in the study with three groups, training plans with elastic bands were provided 31.
In another of the studies, the investigators applied for the program 3 years after the surgery 33, with high-intensity characteristics, and in another study applied 12 to 24 months after the surgery, aerobic training combined with resistance 34.
In the quasi-experimental study, smaller samples were used, and flexibility was also stimulated 35. Only one study applied high-intensity training and all of them used isolated or combined aerobic training 36.
Summary of Results
The search strategy was limited to finding the most recent studies from the last 10 years, including publications in all languages. Although in history several reports have referred to weight loss techniques, bariatric surgery is a 21st-century surgery. Its development only started reported in 2000, with the highest number of scientific publications starting in 2008, so our time interval corresponds to a period between 2011 and 2022. However, we only have one study from 2011 and most of them are longer than the year 2017, with analyses in the immediate postoperative period. Only one study carried out the exercise program in a longer postoperative period, at 3 years after surgery 33.
The age range of subjects in almost all studies from 18 to 65 years old, with samples between 15 and 60 subjects, divided into an experimental group (GI) and a control group (CG). Only one study worked with two intervention groups and a control group, and in this study, we have the largest sample (n = 49) 31. It should be noted that in this study with a larger number of subjects, the structured exercise was prescribed to the subjects and the monitoring was self-reported, there was no face-to-face monitoring.
Experimental studies were based on exercise programs developed after bariatric surgery and only one study started a program at a later stage at 37 months after surgery 33.
The studies were based on structured physical exercise programs developed after surgery, lasting between 12 and 24 weeks, starting mostly between 1 and 3 months after surgery. All studies had evaluations before the intervention, which in most corresponded to before surgery 31,32,34–37, and all had evaluations after the program.
Anthropometry and body composition
Regarding the instruments used, in all studies, anthropometric and body composition assessments were carried out with bioimpedance31,33–35,37 or with Dual-energy X-ray absorptiometry (DEXA) 38, and in half of the studies waist and hip measurements were evaluated 33–36.
Significant improvements were found in all body composition, including a significant increase in muscle mass, with combined exercise, in addition to improvements in weight regain, quality of life, and physical fitness 31–34.
In all studies, there were different results in the intervention group, regardless of the type of exercise, although only some of them showed significant differences. Namely in the decrease in fat mass, the increase in muscle mass, and the increase in excess weight loss 33, with supervised, combined, resistance, endurance, and progressive exercise. In the study that had two intervention groups with aerobic and aerobic exercise plus strength, there was no difference between the groups, but there was concern for the control group. Despite not having significant results, the group with combined exercise had better results than the group that did not have combined exercise, which performed aerobic exercise 31.
Even with programs starting later after surgery, 12 to 24 months, the results with combined exercise are significantly better when we talk about body composition, namely muscle mass. The same results were found in the other two studies, with evidence that combined exercise significantly reduces fat mass and increases muscle mass and bone mass, with a greater reduction in waist and hip 32,33.
Physical function
Muscle strength was assessed in 6 of the studies using the handgrip 31,32,34,35,37,38 and/or one repetition maximum (1RM leg extension 38; 1RM Chest and leg press 35).
One of the studies assessed muscle quality through an assessment of the cross-sectional area of the right thigh muscle by magnetic resonance imaging 38.
In terms of functional capacity, there were assessments in 4 studies, with the six-minute walk test (6MWT) 32, shuttle walk test 34, 12-minute walk run test 31, and sit-to-stand 31,32,34,35, the latter being used in three of the studies.
Physical fitness was assessed in three studies by VO2 max33,35,36 and the Borg scale was used in two studies by 32,36, to measure perceived exertion.
The results of muscular strength, which was mostly assessed by handgrip, showed improvements in all intervention groups, but only significant with combined exercise (p < 0.05) 32. The sit-to-stand test and 1RM leg extension were also used, with significant differences in the combined exercise.
It is important to mention that in the study where the investigators evaluated the cross-sectional area of the right thigh muscle through magnetic resonance imaging, they did not find significant differences with the application of resistance training 38.
Maximum oxygen consumption (VO2 max) has been an important assessment of physical fitness and in the obese population, it is considered an important parameter to analyze morbidities associated with excess weight 37. It proves to be an important parameter to assess exercise capacity, but also an important independent predictor of cardiovascular risk andoverall mortality 38.
Only 3 studies evaluated physical fitness through VO2 max with significant improvements in the intervention group, regardless of the type of exercise performed. There are references that the increase in lung function, which can occur after surgery, leads to a significant increase in VO2 max and that supervised resistance training helps to improve muscle strength and functional autonomy, increasing the patient's functional capacity 35. An improved VO2 max is largely due to an increase in peak blood flow, which increases the maximum rate at which oxygen is supplied and extracted by the skeletal muscle system 26,27.
Physical exercise
Physical activity was evaluated in 3 studies by IPAQ 32,34, in 2 studies with accelerometer 34,36, in 2 studies by self-report 31,35, and 1 study by indirect calorimetry 36. Self-monitored feeding was only evaluated in 3 studies 31,34,36 and metabolism was calculated in one of these studies 37.
In all studies, the practice of structured physical exercise is directly proportional to weight loss and improvement in body composition, that is, more physical exercise means better body composition. Even in the studies in which there were no significant differences, the results were always different in the groups subject to intervention, that is, the groups with intervention obtained better results on body composition.
Significant differences regarding body composition existed in the groups with combined exercise (p = 0.039; p = 0.013) 32,33, since in interventions with resistance or aerobic exercises, no significant improvements were observed, despite better results relative to the control group.
Combined exercise achieves an improvement in anthropometric parameters, more specifically in muscle mass, even though it was started one year after surgery 34 (p = 0.034) and three years after surgery (p = 0.000) 33.