BACKGROUND: Improving mobility outcomes after hip fracture is key to recovery. Possible strategies include gait training, exercise and muscle stimulation. This is an update of a Cochrane Review last published in 2011. OBJECTIVES: To evaluate the effects (benefits and harms) of interventions aimed at improving mobility and physical functioning after hip fracture surgery in adults. SEARCH METHODS: We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, trial registers and reference lists, to March 2021. SELECTION CRITERIA: All randomised or quasi-randomised trials assessing mobility strategies after hip fracture surgery. Eligible strategies aimed to improve mobility and included care programmes, exercise (gait, balance and functional training, resistance/strength training, endurance, flexibility, three-dimensional (3D) exercise and general physical activity) or muscle stimulation. Intervention was compared with usual care (in-hospital) or with usual care, no intervention, sham exercise or social visit (post-hospital). DATA COLLECTION AND ANALYSIS: Members of the review author team independently selected trials for inclusion, assessed risk of bias and extracted data. We used standard methodological procedures expected by Cochrane. We used the assessment time point closest to four months for in-hospital studies, and the time point closest to the end of the intervention for post-hospital studies. Critical outcomes were mobility, walking speed, functioning, health-related quality of life, mortality, adverse effects and return to living at pre-fracture residence. MAIN RESULTS: We included 40 randomised controlled trials (RCTs) with 4059 participants from 17 countries. On average, participants were 80 years old and 80% were women. The median number of study participants was 81 and all trials had unclear or high risk of bias for one or more domains. Most trials excluded people with cognitive impairment (70%), immobility and/or medical conditions affecting mobility (72%). In-hospital setting, mobility strategy versus control Eighteen trials (1433 participants) compared mobility strategies with control (usual care) in hospitals. Overall, such strategies may lead to a moderate, clinically-meaningful increase in mobility (standardised mean difference (SMD) 0.53, 95% confidence interval (CI) 0.10 to 0.96; 7 studies, 507 participants; low-certainty evidence) and a small, clinically meaningful improvement in walking speed (CI crosses zero so does not rule out a lack of effect (SMD 0.16, 95% CI -0.05 to 0.37; 6 studies, 360 participants; moderate-certainty evidence). Mobility strategies may make little or no difference to short-term (risk ratio (RR) 1.06, 95% CI 0.48 to 2.30; 6 studies, 489 participants; low-certainty evidence) or long-term mortality (RR 1.22, 95% CI 0.48 to 3.12; 2 studies, 133 participants; low-certainty evidence), adverse events measured by hospital re-admission (RR 0.70, 95% CI 0.44 to 1.11; 4 studies, 322 participants; low-certainty evidence), or return to pre-fracture residence (RR 1.07, 95% CI 0.73 to 1.56; 2 studies, 240 participants; low-certainty evidence). We are uncertain whether mobility strategies improve functioning or health-related quality of life as the certainty of evidence was very low. Gait, balance and functional training probably causes a moderate improvement in mobility (SMD 0.57, 95% CI 0.07 to 1.06; 6 studies, 463 participants; moderate-certainty evidence). There was little or no difference in effects on mobility for resistance training. No studies of other types of exercise or electrical stimulation reported mobility outcomes. Post-hospital setting, mobility strategy versus control Twenty-two trials (2626 participants) compared mobility strategies with control (usual care, no intervention, sham exercise or social visit) in the post-hospital setting. Mobility strategies lead to a small, clinically meaningful increase in mobility (SMD 0.32, 95% CI 0.11 to 0.54; 7 studies, 761 participants; high-certainty evidence) and a small, clinically meaningful improvement in walking speed compared to control (SMD 0.16, 95% CI 0.04 to 0.29; 14 studies, 1067 participants; high-certainty evidence). Mobility strategies lead to a small, non-clinically meaningful increase in functioning (SMD 0.23, 95% CI 0.10 to 0.36; 9 studies, 936 participants; high-certainty evidence), and probably lead to a slight increase in quality of life that may not be clinically meaningful (SMD 0.14, 95% CI -0.00 to 0.29; 10 studies, 785 participants; moderate-certainty evidence). Mobility strategies probably make little or no difference to short-term mortality (RR 1.01, 95% CI 0.49 to 2.06; 8 studies, 737 participants; moderate-certainty evidence). Mobility strategies may make little or no difference to long-term mortality (RR 0.73, 95% CI 0.39 to 1.37; 4 studies, 588 participants; low-certainty evidence) or adverse events measured by hospital re-admission (95% CI includes a large reduction and large increase, RR 0.86, 95% CI 0.52 to 1.42; 2 studies, 206 participants; low-certainty evidence). Training involving gait, balance and functional exercise leads to a small, clinically meaningful increase in mobility (SMD 0.20, 95% CI 0.05 to 0.36; 5 studies, 621 participants; high-certainty evidence), while training classified as being primarily resistance or strength exercise may lead to a clinically meaningful increase in mobility measured using distance walked in six minutes (mean difference (MD) 55.65, 95% CI 28.58 to 82.72; 3 studies, 198 participants; low-certainty evidence). Training involving multiple intervention components probably leads to a substantial, clinically meaningful increase in mobility (SMD 0.94, 95% CI 0.53 to 1.34; 2 studies, 104 participants; moderate-certainty evidence). We are uncertain of the effect of aerobic training on mobility (very low-certainty evidence). No studies of other types of exercise or electrical stimulation reported mobility outcomes. AUTHORS' CONCLUSIONS: Interventions targeting improvement in mobility after hip fracture may cause clinically meaningful improvement in mobility and walking speed in hospital and post-hospital settings, compared with conventional care. Interventions that include training of gait, balance and functional tasks are particularly effective. There was little or no between-group difference in the number of adverse events reported. Future trials should include long-term follow-up and economic outcomes, determine the relative impact of different types of exercise and establish effectiveness in emerging economies.