Poor cardiopulmonary fitness is an important risk factor for postoperative complications, yet a feasible, objective and prognostically accurate method to assess preoperative fitness has not been established. The 6 min walk test (6MWT) is a simple, inexpensive and widely applicable measure that shows promise for predicting postoperative risk. However, robust data are lacking on whether the 6MWT accurately predicts complications, provides incremental prognostic value beyond routinely collected clinical factors or outperforms simpler alternatives such as questionnaires, cardiac biomarkers or grip strength testing. The Functional Assessment for Surgery by a Timed Walk (FAST Walk) study is designed to address these knowledge gaps by evaluating whether the 6MWT improves prediction of key postoperative outcomes compared with clinical factors and simpler measures of fitness.

The FAST Walk study is an international multicentre prospective cohort study of 1672 adults (≥40 years) undergoing major elective non-cardiac surgery at centres in Canada, Hong Kong, Australia, Spain and the Netherlands. Participants complete a preoperative 6MWT and baseline assessments of comorbidities, self-reported cardiopulmonary fitness (MET: Re-evaluation for Perioperative Cardiac Risk questionnaire), biomarkers (N-terminal pro-B-type natriuretic peptide) and grip strength. The primary outcome is 30-day death or major postoperative complication, defined as Clavien-Dindo grade II or higher. Secondary outcomes are (1) death or new significant disability at 90 days after surgery and (2) days alive and out of hospital at 30 days after surgery. Disability is measured using the short-form WHO Disability Assessment Schedule 2.0 instrument. Multivariable regression models and complementary metrics of prediction performance will be used to determine whether 6MWT distance adds prognostic value beyond routinely collected clinical factors and simpler measures of fitness.

The FAST Walk study has received research ethics board approval at all participating sites. Recruitment commenced in June 2024, with completion of participant follow-up expected in 2026. Findings will be disseminated through peer-reviewed publications and conference presentations, with the primary results anticipated in 2027.

NCT06412367.

Metabolic bariatric surgery (MBS) can lead to substantial fat-free mass loss (FFML) due to malnutrition, decreased protein intake and insufficient physical activity. Disproportional FFML has been associated with an increased risk for adverse health outcomes. Resistance training (RT) combined with protein intake contributes to maintenance and increase of fat-free mass (FFM) in healthy individuals. However, it is unclear whether RT and protein supplementation can prevent FFML after MBS.

In the EffectiveNess of pRotein supplementatIon Combined witH resistance Exercise training to counteract Disproportional fat-free mass loss following metabolic bariatric surgery (ENRICHED) randomised controlled trial, 400 patients scheduled to undergo MBS will be randomised in a 1:1 ratio to the ENRICHED perioperative care programme (intervention group) or the standard perioperative care programme of the Dutch Obesity Clinic (control group). The study is currently recruiting participants at two centres in the Netherlands: Nieuwegein and Amsterdam. The postoperative standard programme consists of 13 group sessions spread over a period of 18 months. As part of the ENRICHED programme, RT and protein supplementation will be added 3 weeks after MBS. Additional whole-body RT consists of home-based training sessions two to three times a week, and supervised RT sessions of 45–60 min once weekly, performed at 60–75% of one-repetition maximum (1-RM). Protein supplementation will start by adding 20 g of whey protein to the daily intake. The supplementation will be gradually increased with 20 g every 4 weeks until a total of 60 g whey protein a day is reached. After 12 weeks of protein supplementation, the focus shifts towards incorporating protein-rich food products into the daily dietary intake. The primary endpoint is the prevalence of disproportional FFM loss, defined as FFML/total weight loss ≥30%, at 3 months post-MBS. Secondary endpoints are differences in body composition, muscle strength and function, cardiorespiratory fitness, (cardio)metabolic health, health-related quality of life, gastrointestinal discomfort, cost-effectiveness of the intervention and treatment satisfaction. Outcomes will be assessed preoperatively and at 3, 6 and 12 months postoperatively.

The study protocol V.2.0 was approved by the Medical Research Ethics Committee Oost-Nederland (NL-OMON57119) on 9 April 2025. All participants will provide written informed consent prior to enrolment. Study findings will be disseminated through peer-reviewed publications and conference presentations. Insights gained in this study will provide evidence for a patient-tailored intervention that could be implemented in clinical practice.

NCT07156552.