Summary of findings
The aim of this review was to examine the effects of ERS within three populations: those with CV, MH, and MSK disorders. Length of schemes, and mode and type of exercise used with each sub-group, was reviewed due to inconsistencies in previous research [2]. At present, strong research is lacking to support ERS of 12-week duration which are recommended by NICE [22], particularly with respect to adherence to PA prescribed; evidence suggests schemes do not tailor the mode and type of exercise specifically to suit health disorders; and the evidence to support ERS in specific disorders in relation to adherence and improving health outcomes is poor [2, 25, 28]. These two key variables will be discussed further in detail.
Schemes have evidenced the effectiveness in CV [25, 43, 47] and MH disorders [25, 41], but evidence is lacking around MSK disorders. Duration and type of ERS were elements to consider in terms of their impact on outcomes. Overall, ERS resulted in significant reductions in BP [45, 47, 49, 50] and BMI [25, 47, 49, 50], and increased adherence to the PA prescribed over time [24, 40, 41, 43, 44, 49]. Self-reported PA levels also increased [25, 41, 44, 49]. Prior to this review, a previous systematic review suggested that separately reported health outcomes relating to referral reason have not been reported [2]. Within this review, the health disorder sub-groups were individually analysed to review any disorder-specific outcomes.
Within the CV sub-group, not all studies reported a disorder-specific measure [24, 40,41,42, 44, 46]. To get a true representation of any improvements made in the CV sub-group, all studies should have reported on the disorder-specific measures. Of those who did report on CV-specific measures, all showed improvements in BP and BMI [25, 45, 47].
Individuals referred for MH disorders, responded positively to either gym based exercise sessions or group aerobic exercise sessions. Disorder-specific measures such as HADS showed that ERS significantly reduced anxiety and depression scores [25, 41]. These were self-reported measures of anxiety and depression. Other measures were also reported, but most individuals referred tend to have more than one health disorder [22], which can be observed in the articles reviewed in Tables 1, 2 and 3.
MSK disorders have limited research of the effects of ERS on disorder-specific outcomes. There are no direct measures used to evaluate the effects of ERS on the MSK disorders (such as measuring pain felt in the injured area/range of movement/functional outcomes). Using measures such as Lower Extremity Functional Scale (LEFS), Lower Limb Functional Index (LLFI) [53], McGill Pain Questionnaire (MPQ) [52] or the Visual Analogue Scale [54] could be tools which could more accurately measure MSK disorders. At present one in five people consult a GP about MSK pain each year. Support and treatment for MSK chronic pain account for approximately 4.6 million appointments per year [51]. If further research into the effectiveness of ERS on MSK disorders was conducted then, if effective, GP time could be reduced, saving time and money for the NHS.
Length of schemes
ERS tend to conclude after a 10–12-week exercise programme within England and Ireland [2, 23], although longer length schemes offer more opportunity for individuals to gain long term health benefits of PA [43, 44, 50]. NICE [22] who set out the guidelines for ERS, recommend schemes last for at least 12 weeks. Research regarding longer length schemes is extremely limited. However, a previous study suggests that longer length schemes have been beneficial for individuals with CV disease risk and MH disorders, increasing PA levels whilst also being more cost-effective [24]. Research relating to 12-week ERS suggests that significant health outcomes and changes in PA do not occur [27]. Many studies likely have employed 12-week schemes to meet the guidelines set out by NICE [22]. However, if ERS scheme’s length recommendations were increased by NICE, then it might be expected that the implementation of ERS schemes would follow suit and thus greater effects on health outcomes might occur.
Shorter-length ERS (8–10 weeks) did not produce the same outcomes as schemes of longer lengths. For example, a scheme of short length (8 weeks) did not have statistically significant effects on physiological and psychosocial outcomes for individuals referred for MH disorders [48]. However, Webb, et al. [47] did find significant changes in BP, through an 8-week long scheme for participants referred with CV disorders, although longer length schemes produced better outcomes [43, 45]. Thus, it could be argued that shorter length schemes should have the potential to impact CV disorders, though longer schemes may be required for MH disorders. Past research has showed that exercise can have positive impacts on CV outcomes after only a couple of weeks of participating in 30-min of regular vigorous exercise [55]. Further research supports that four weeks of aerobic and resistance exercise can improve blood pressure, arterial stiffness and blood flow [56, 57]. It has also been reported that diastolic and systolic blood pressure can be reduced after one exercise session, and remain low for up to 90 min’ post-exercise session [58,59,60]. Thus, could support the use if 8-week ERS for participants with CV conditions, in the improvement of CV-specific health outcomes such as systolic and diastolic blood pressure.
Mid length schemes (11–19 weeks) did show significant improvement in the conditions examined. As noted, NICE [22] schemes have stated that schemes should be at least 12 weeks in length. Various other clinical and traditional exercise programmes are often longer than 12 weeks [24, 61,62,63] and demonstrate greater efficacy for improving health conditions [47]. Therefore, ERS guidelines should perhaps be adapted to match this. Compared with an 8-week ERS, Webb, et al. [47] found that within an 8-week community-based outdoor exercise programme, participants achieved higher intensities of effort resulting in pronounced beneficial effects on health including: significant CV disease risk-lowering; reduced blood pressure; arterial stiffness; and blood lipids. Increasing the length of ERS may permit them to produce results more comparable with other exercise and PA interventions. Further, consideration of the mode of exercise, could improve the effectiveness of ERS. To support this, Duda, et al. [25] found that there were no significant changes in BP in schemes of 10–12 weeks in length. This may be due to other cofounding influences which may have affected blood pressure not allowing it to reduce in the short term, including medication [64]. However, combinations of longer duration exercise interventions with medication may potentially provide a more stable and positive effect on blood pressure [65].
Studies of schemes following the NICE [22] recommended length of 12 weeks found that, compared to no intervention, self-reported PA levels did not differ [49]. This could suggest that 12 weeks is not long enough to initiate changes in PA which are perceivable by participants. Longer length schemes may improve self-reported PA. However, schemes of this length had some impact on reducing sedentary behaviours, but it was suggested that this was unlikely to be sustained and lead to long term health benefits such as weight loss, sustained reduced BP, and decreased BMI [49].
Longer-length schemes (20+ weeks) have been shown to be beneficial in improving various health outcomes and aid healthier behaviours [7, 45, 50]. All longer-length schemes reviewed had positive impacts on health, reducing BP and BMI [26], improving PA levels [24] and increasing adherence to the prescription [43,44,45, 50]. At present, guidelines use 12-week ERS as a basis for providers to follow [22] whereas a change in guidelines to introduce longer length schemes might result in more providers delivering ERS of such length in the UK and produce better health outcomes as well as cost savings for the NHS [24].
Type and mode of exercise
The most common type of exercise employed in ERS was one-to-to one supervised gym based exercise sessions, incorporating both resistance and cardiovascular exercise for all health conditions [24, 25, 41, 43, 44, 46]. Individuals referred for CV disorders, who incorporate both resistance and aerobic exercises into their prescription, saw greater improvements in CV health which is supported by past research [66, 67]. This is in line with results found within studies included in this review [25, 45, 47].
MH disorders also improved significantly when individuals took part in aerobic and resistance training gym based exercise. Scores relating to depression and anxiety had all improved [24, 25, 41, 43, 46]. Physical activity levels had also increased. This could suggest that gym based exercise sessions incorporating aerobic and resistance exercise are best suited in reducing MH disorders. Indeed, a recent meta-analysis supports the use of resistance exercise in treatment of anxiety [12] while previous reviews also support the benefits of aerobic training [68]. Both are clearly effective, yet may exert specific effects upon MH outcomes. Thus, the combined approach may be best suited for ERS in MH disorders.
There is very limited research on ERS with MSK disorders, therefore it is difficult to compare the results from this review to past literature. Only three articles were found to be relevant for this review for this population [46, 49, 50]. All comprised of predominantly one-to-one exercise sessions, and all reported increases in adherence to PA prescribed across time. Unfortunately, none of the studies included any outcomes related to the patient’s MSK disorders such as pain or disability. Considering that all also utilised similar interventions it is therefore difficult to discern specifically the comparative efficacy of different types of ERS in MSK disorders. However, there is evidence to suggest that, similarly to other disorders, using both aerobic and resistance exercises do improve musculoskeletal disorders including osteoarthritis of the knee [69].
Aerobic exercise sessions were solely the mode of some schemes [40, 48]. However, as has been shown, prescriptions of exercise that solely focus on aerobic exercise may be less efficacious as combined approaches. Resistance training exerts a wide range of benefits alongside aerobic training [70, 71]. Additionally, aerobic exercise-only ERS present its own issues such as lack of efficacy as typically employed in reducing or stopping lean body mass loss, and associated loss in resting metabolic rate per decade affiliated with normal ageing [72]. That the majority of research has focused upon the health benefits gained from aerobic training has made this mode of exercise a primary focal point within PA guidelines according to literature [73]. However, it has been argued that resistance training based interventions should have a greater emphasis in public health approaches [74].
At present NICE guidelines [22] do not advise on the type and mode of exercise that should be employed within ERS, though the majority of studies here show that one-to-one gym based exercise sessions employing both aerobic and resistance training are effective. Tailoring the type and mode of exercise to be disorder-specific could also influence adherence and health outcomes. The evidence reviewed here suggests that a combining both aerobic and resistance exercise is effective across a range of disorders. However, there is a lack of research directly comparing different ERS utilising different exercise approaches. Some individuals may also be referred for multiple disorders, and this may need an entirely different approach. Usually, a referral is made for one health disorder, but if an individual is referred for more than one disorder, then a more nuanced exercise programme may be required. This may also mean that the scheme’s length needs adjusting to suit the amount of disorders referred for. Further research is required to analyse the type and mode of exercise prescribed dependant on the disorders and health outcomes upon completion.
Implications for future research and clinical practice
The usual length of schemes in most ERS is 12 weeks long [22]. Research within this review has found that longer schemes (20 weeks+) may provide better effects on adherence to the prescription and health outcomes [43, 44, 50]. This conclusion suggests that recommendations set out by NICE [22] might benefit from being updated to emphasise the importance of longer schemes. Indeed, as noted, longer schemes have also been shown to be more cost effective [24]. A key challenge for future research is to identify ways to maximise uptake and improve adherence to PA prescribed until completion across all schemes.
At present, ERS are not meeting several standards set out by NICE including: referral of individuals who are sedentary/inactive but otherwise healthy; incorporate behaviour change into individual approaches; agreeing goals and sticking to action plans with regular follow ups with no-shows; and tailoring the intervention to individual needs and develop coping plans to prevent relapse. At present, though often one-to-one sessions are employed, schemes are typically generic and not personalised to suit individuals and their health disorders specifically. One-to-one gym based exercise sessions can potentially be tailored to individual needs of each participant and health disorder. However, within this review, there was no information given within studies on how programmes were tailored to suit each participant, or if they were at all. At present, NICE [22] have not set any guidelines on the type and mode of exercise which is to be administered, let alone disorder-specific exercise guidelines. Broadly the results of this review suggest that combined approaches of both cardiovascular and resistance exercises are effective across disorders. Yet there is little research directly comparing different approaches, or comparing generic interventions to those with specific individualisation. By tailoring programmes to suit each patient, ERS could address some of the barriers which some patients report stop them from adhering to schemes, including unfamiliar environment, quality of interaction with exercise provider, boredom, exercise preferences, poor record keeping, and clinical disorder [21].
Economic impact of ERS was reported in one study [42]. Results show that for sedentary individuals with CVD, and sedentary individuals with a MH disorder, the estimated cost per quality-adjusted life year (QALY) was £12,834 and £8414 respectively. Benefits and incremental lifetime costs linked with ERS were found to be sensitive to variations in the relative risk of ERS costs and becoming physically active. ERS is more expensive compared to usual care, due to the additional mean lifetime costs of £170 per individual, although, it is more effective in leading to a lifetime mean QALY gain of 0.008 per individual.
Although schemes need to be cost-effective, future training of exercise referral instructors could be adapted to improve exercise prescriptions with updated evidence-based guidelines. This may reduce the burden of cost on ERS, as instructors will be more equipped to prescribe exercise which may have greater effects on health outcomes. An evaluation of a scheme in Belfast found that they calculated a return of approximately £7 for every £1 invested into their Healthwise Physical Activity Referral Programme [75]. Further, Anokye, et al. [42] reviewed the cost-effectiveness of ERS. It was found that ERS was linked to a slower increase in lifetime costs and benefits. ERS was found to be 51–88% cost-effective.
Other identified issues within this review include that control interventions are often not explained in detail [25, 40, 43, 48, 50, 64]. They must distinctly differ from ERS, and be explained in detail, in order to examine comparative effectiveness. Another identified issue, which may also provide evidence for NICE policies is that health-economic evaluations are often not incorporated into studies to review the cost-effectiveness of the schemes alongside the effectiveness on health outcomes. Evidence of cost-effectiveness is also required to understand the wider benefits of GPs referring patients to ERS reducing burdens on the NHS.
