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Weight-loss surgery makes the stomach much smaller, and sometimes reroutes part of the bowel, so that people eat less and absorb differently. It is relevant here because obesity affects breathing — particularly sleep apnoea — and because losing a large amount of weight quickly costs muscle as well as fat unless exercise is part of the plan.
Why this page is here
Bariatric surgery is abdominal and metabolic, not thoracic. It appears in this section because its principal perioperative risks are respiratory, because its strongest non-metabolic benefit is on sleep-disordered breathing, and because the physiotherapy contribution — before, during and long after — is substantial and frequently absent.
The operations
| Procedure | What it does |
|---|---|
| Sleeve gastrectomy | A large portion of the stomach is removed, leaving a narrow tube. Now the most commonly performed procedure. |
| Roux-en-Y gastric bypass | A small gastric pouch is joined directly to the jejunum, bypassing the remaining stomach and duodenum. Greater metabolic effect; more nutritional consequences. |
| One-anastomosis gastric bypass | A single-loop variant, technically simpler. |
| Adjustable gastric band | Largely historical; declining because of long-term failure and reoperation rates. |
Almost all are performed laparoscopically, which substantially reduces pulmonary complications compared with open surgery, and within enhanced-recovery pathways that specify early mobilisation and early oral intake.1 Beyond weight, the metabolic effect is real: the STAMPEDE trial demonstrated superior glycaemic outcomes at five years compared with intensive medical therapy in type 2 diabetes.2
The respiratory picture
Obstructive sleep apnoea
Sleep-disordered breathing is highly prevalent in this population and frequently undiagnosed at presentation. Screening with a validated tool such as STOP-Bang is standard practice before bariatric surgery, because undiagnosed obstructive sleep apnoea materially increases perioperative airway and respiratory risk.3
Surgery improves it substantially: prospective multicentre data show marked reduction in apnoea–hypopnoea index at 12 months, with a proportion of patients achieving remission — though a significant minority have residual disease and continuing continuous positive airway pressure therapy should not be stopped on the assumption of cure without repeat testing.4 See Obstructive Sleep Apnoea.
Obesity hypoventilation syndrome
Daytime hypercapnia with obesity and sleep-disordered breathing, in the absence of another cause. It carries higher perioperative risk than obstructive sleep apnoea alone and requires established positive airway pressure therapy before elective surgery.5 See Obesity Hypoventilation Syndrome.
Perioperative mechanics
Functional residual capacity is already reduced by obesity and falls further under anaesthesia, so atelectasis is early, extensive and predictable. Practical consequences: ramped and head-up positioning, early mobilisation, and a low threshold for positive airway pressure. Concern that positive pressure might threaten a fresh anastomosis has not been borne out, and established continuous positive airway pressure therapy is generally continued post-operatively — confirm with the surgical team, but do not assume it is contraindicated.6
Venous thromboembolism risk is elevated, which is a further argument for early and frequent mobilisation. See Post-operative Pulmonary Complications.
Exercise around the operation
Systematic review and meta-analysis of exercise training before and after bariatric surgery found improvements in cardiorespiratory fitness and, importantly, evidence that post-operative training helps preserve lean body mass during rapid weight loss.7
A substantial share of the weight lost after bariatric surgery is lean tissue. In an older or already deconditioned patient this can convert a metabolic success into a functional decline — and sarcopenic obesity is a worse functional state than the starting point. Progressive resistance training with adequate protein intake is the countermeasure, and it is the clearest physiotherapy indication in the whole pathway.
Practical prescription
- Before surgery: aerobic and resistance conditioning where the window allows, screening and optimisation of sleep-disordered breathing, and the standard pre-operative respiratory education contact.
- Immediately after: mobilise on the day of surgery, sit upright, continue positive airway pressure where prescribed.
- Weeks to months: progressive resistance training two to three times weekly alongside aerobic work; avoid heavy abdominal loading until the surgical team clears it.
- Musculoskeletal load falls as weight does — knee and back pain often improve, which opens up exercise options that were previously unavailable. Reassess capacity regularly rather than working to the initial prescription.
- Long term: exercise adherence predicts weight maintenance. This is where most programmes stop and most regain happens.
Pharmacological weight management increasingly overlaps with, and sometimes substitutes for, surgery — including in sleep apnoea, where incretin therapy has now shown benefit. See GLP-1 & Weight-Management Injections.
Role of the physiotherapist
Screen for and respect sleep-disordered breathing, and do not let anyone stop continuous positive airway pressure on the assumption that weight loss has cured it. Position, mobilise and expect atelectasis. Then take the long view: the operation removes weight, but only training preserves the muscle underneath it, and that determines whether the patient ends up fitter or merely lighter.
Evidence summary
Framing. Bariatric surgery is one of the few interventions that meaningfully modifies obstructive sleep apnoea and obesity hypoventilation, which is why it belongs in a cardiorespiratory resource.4,5 Its perioperative risk profile is dominated by airway and respiratory events rather than by the abdominal procedure itself, and its main long-term physiotherapy question is the defence of lean mass during rapid weight loss.7
Evidence — metabolic and respiratory outcomesSTAMPEDE established durable glycaemic superiority over intensive medical therapy at five years.2 Prospective multicentre data demonstrate substantial reduction in apnoea–hypopnoea index at 12 months post-surgery, with incomplete resolution in a meaningful minority — the basis for repeat sleep testing before withdrawing positive airway pressure.4 ATS guidance frames the evaluation and management of obesity hypoventilation syndrome, including pre-operative optimisation.5
Evidence — exerciseMeta-analysis of exercise training before and after bariatric surgery reports improved cardiorespiratory fitness and attenuated loss of lean body mass, the latter being the outcome with the greatest functional significance.7 Enhanced-recovery pathways for bariatric surgery incorporate early mobilisation as standard.1 Perioperative guidance supports continuation of established positive airway pressure therapy.6
Physiotherapy implicationsTreat STOP-Bang screening and positive airway pressure adherence as within scope.3 Do not accept discontinuation of therapy on the basis of weight loss alone. Position ramped and head-up, mobilise on day zero. Prescribe progressive resistance training as the primary long-term intervention, and reassess capacity frequently as musculoskeletal load falls.
Evidence gapsOptimal timing, intensity and duration of resistance training for lean-mass preservation after bariatric surgery are undefined, and most trials are small with short follow-up. The interaction between incretin pharmacotherapy, surgery and exercise on body composition is largely unstudied. Long-term adherence strategies, which determine weight maintenance, have little high-quality evidence.
References & evidence base
- Małczak P, Pisarska M, Piotr M, Wysocki M, Budzyński A, Pedziwiatr M. Enhanced recovery after bariatric surgery: systematic review and meta-analysis. Obes Surg 2017;27(1):226–235.
- Schauer PR, Bhatt DL, Kirwan JP, et al. Bariatric surgery versus intensive medical therapy for diabetes — 5-year outcomes (STAMPEDE). N Engl J Med 2017;376(7):641–651.
- Chung F, Abdullah HR, Liao P. STOP-Bang questionnaire: a practical approach to screen for obstructive sleep apnea. Chest 2016;149(3):631–638.
- Peromaa-Haavisto P, Tuomilehto H, Kössi J, et al. Obstructive sleep apnoea: the effect of bariatric surgery after 12 months. A prospective multicenter trial. Sleep Med 2017;35:85–90.
- Mokhlesi B, Masa JF, Brozek JL, et al. Evaluation and management of obesity hypoventilation syndrome. An official American Thoracic Society clinical practice guideline. Am J Respir Crit Care Med 2019;200(3):e6–e24.
- Mechanick JI, Apovian C, Brethauer S, et al. Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures. Surg Obes Relat Dis 2020;16(2):175–247.
- Bellicha A, van Baak MA, Battista F, et al. Effect of exercise training before and after bariatric surgery: a systematic review and meta-analysis. Obes Rev 2021;22(Suppl 4):e13296.
References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.
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