Abstract: We included six trials (483 adult ICU participants). Exercise-based interventions were delivered on the ward in two studies; both on the ward and in the community in one study; and in the community in three studies. The duration of the intervention varied according to length of hospital stay following ICU discharge (up to a fixed duration of 12 weeks). Risk of bias was variable for all domains across all trials. High risk of bias was evident in all studies for performance bias, although blinding of participants and personnel in therapeutic rehabilitation trials can be pragmatically challenging. For other domains, at least half of the studies were at low risk of bias. One study was at high risk of selection bias, attrition bias and other sources of bias. Risk of bias was unclear for the remaining studies across domains. We decided not to undertake a meta-analysis because of variation in study design, types of interventions and outcome measurements. We present a narrative description of individual studies for each outcome. All six studies assessed functional exercise capacity, although we noted wide variability in the nature of interventions, outcome measures and associated metrics and data reporting. Overall quality of the evidence was very low. Individually, three studies reported positive results in favour of the intervention. One study found a small short-term benefit in anaerobic threshold (mean difference (MD) 1.8 mL O2/kg/min, 95% confidence interval (CI) 0.4 to 3.2; P value = 0.02). In a second study, both incremental (MD 4.7, 95% CI 1.69 to 7.75 watts; P value = 0.003) and endurance (MD 4.12, 95% CI 0.68 to 7.56 minutes; P value = 0.021) exercise testing results were improved with intervention. Finally self reported physical function increased significantly following use of a rehabilitation manual (P value = 0.006). Remaining studies found no effect of the intervention. Similar variability was evident with regard to findings for the primary outcome of health-related quality of life. Only two studies evaluated this outcome. Individually, neither study reported differences between intervention and control groups for health-related quality of life due to the intervention. Overall quality of the evidence was very low. Four studies reported rates of withdrawal, which ranged from 0% to 26.5% in control groups, and from 8.2% to 27.6% in intervention groups. The quality of evidence for the effect of the intervention on withdrawal was low. Very low-quality evidence showed rates of adherence with the intervention. Mortality ranging from 0% to 18.8% was reported by all studies. The quality of evidence for the effect of the intervention on mortality was low. Loss to follow-up, as reported in all studies, ranged from 0% to 14% in control groups, and from 0% to 12.5% in intervention groups, with low quality of evidence. Only one non-mortality adverse event was reported across all participants in all studies (a minor musculoskeletal injury), and the quality of the evidence was low. At this time, we are unable to determine an overall effect on functional exercise capacity, or on health-related quality of life, of an exercise-based intervention initiated after ICU discharge for survivors of critical illness. Meta-analysis of findings was not appropriate because the number of studies and the quantity of data were insufficient. Individual study findings were inconsistent. Some studies reported a beneficial effect of the intervention on functional exercise capacity, and others did not. No effect on health-related quality of life was reported. Methodological rigour was lacking across several domains, influencing the quality of the evidence. Wide variability was noted in the characteristics of interventions, outcome measures and associated metrics and data reporting. If further trials are identified, we may be able to determine the effects of exercise-based intervention following ICU discharge on functional exercise capacity and health-related quality of life among survivors of critical illness.

Plain-language summary: We included six studies that involved 483 participants (298 male, 185 female) over the age of 18 years. Participants had received breathing support from a machine (been mechanically ventilated) for longer than 24 hours whilst in the ICU and had begun an exercise programme after leaving the ICU. Studies were carried out in the UK, Australia, the USA and Italy. Exercise programmes were delivered on the ward in two studies; on the ward and in the community in one study; and in the community in three studies. The duration of the intervention varied according to length of hospital stay after ICU discharge up to a fixed time of 12 weeks. Exercises included arm or leg cycling, walking and general muscle strengthening at home, provision of self help manuals and hospital-based multi-exercise programmes carried out in physiotherapist-led gymnasiums. Three of the six studies were funded by government health research funding agencies. One study was supported by combined funding from an independent charity and a commercial company (with no interest in the results of the study). One study did not report a funding source, and another was funded by an academic health research agency. We were unable to determine an overall result for the effects of exercise-based interventions. Three studies reported improvement in functional exercise capacity following completion of the exercise programme, and the other three found no effects of treatment. Only two studies measured patient-reported health-related quality of life, and both of these studies showed no effects related to treatment. Again, we were unable to reach an overall conclusion. No study included an evaluation of acceptance of the treatment by patients or the experience of patient participation in an exercise-based programme. We found considerable differences across included studies regarding types of exercise, how measurements of functional exercise capacity were collected, ways by which results were presented and people who had been critically ill. Exercise programmes were compared with usual care, with lack of acknowledgement of the standard level of rehabilitation and exercise in usual practice. In addition, we found variability in how well the studies were performed. We were unable to perform any statistical tests on study findings or to make firm conclusions because of this variability. The overall quality of the evidence was very low for these reasons. . Evidence is current to May 2014. We reran the search in February 2015 and will deal with studies of interest when we update the review.