Physical Exercise Interventions for Improving Performance-based
Measures of Physical Function in Community-dwelling, Frail
Older Adults: A Systematic Review and Meta-analysisThis section is compiled by Frank M. Painter, D.C.
Send all comments or additions to: Frankp@chiro.org
FROM: Arch Phys Med Rehabil. 2014 (Apr); 95 (4): 753-769 ~ FULL TEXT
OPEN ACCESS Maria Gine-Garriga, PhD, PT, Marta Roque-Figuls, MD, Laura Coll-Planas, MD, Merce Sitja-Rabert, PhD, PT, Antoni Salva, MD
Department of Physical Activity and Sport Sciences,
FPCEE Blanquerna, Universitat Ramon Llull,
Barcelona, Spain
mariagg@blanquerna.url.edu
OBJECTIVE: To conduct a systematic review to determine the efficacy of exercise-based interventions on improving performance-based measures of physical function and markers of physical frailty in community-dwelling, frail older people.
DATA SOURCES: Comprehensive bibliographic searches in MEDLINE, the Cochrane Library, PEDro, and CINAHL databases were conducted (April 2013).
STUDY SELECTION: Randomized controlled trials of community-dwelling older adults, defined as frail according to physical function and physical difficulties in activities of daily living (ADL). Included trials had to compare an exercise intervention with a control or another exercise intervention, and assess performance-based measures of physical function such as mobility and gait, or disability in ADL.
DATA EXTRACTION: Two review authors independently screened the search results and performed data extraction and risk of bias assessment. Nineteen trials were included, 12 of them comparing exercise with an inactive control. Most exercise programs were multicomponent.
DATA SYNTHESIS: Meta-analysis was performed for the comparison of exercise versus control with the inverse variance method under the random-effects models. When compared with control interventions, exercise was shown to improve normal gait speed (mean difference [MD]=.07m/s; 95% confidence interval [CI], .04-.09), fast gait speed (MD=.08m/s; 95% CI, .02-.14), and the Short Physical Performance Battery (MD=2.18; 95% CI, 1.56-2.80). Results are inconclusive for endurance outcomes, and no consistent effect was observed on balance and the ADL functional mobility. The evidence comparing different modalities of exercise is scarce and heterogeneous.
CONCLUSIONS: Exercise has some benefits in frail older people, although uncertainty still exists with regard to which exercise characteristics (type, frequency, duration) are most effective.
KEYWORDS: Exercise; Frail elderly; Meta-analysis; Rehabilitation; Review, systematic
From the FULL TEXT Article:
Background
As individuals get older, they may reach a stage of vulnerability called frailty that precedes and predisposes to disability and physical dependence. The terms frail and frailty are often used in the literature without clear definition or criteria, [1] and there is not yet a consensus on a standardized and valid method of clinically screening for frailty. [2, 3] Frailty is considered highly prevalent in old age and to confer a high risk for falls, worsening mobility, disability, hospitalization, and mortality. [4]
Two main definitions of frailty exist. The first one relates frailty to a physical phenotype consisting of solely physical components and has attracted the most attention of researchers. [4] The most well known of these is the frailty phenotype described by Fried et al, [5] which identifies someone as frail when 3 or more of the following criteria are present: unintentional weight loss, self-reported exhaustion, weakness, slow walking speed, and low levels of physical activity. The second definition has a broader scope and conceptualizes frailty as the result of multiple interacting factors such as having difficulties in activities of daily living (ADL), and social and psychological aspects. [6] This definition was operationalized into the Frailty Index, [7] built as a sum of deficits and able to capture gradations in health status ranging from mild to severe stages, and the risk of adverse outcomes. [8] A review of the literature by Gobbens et al [9] showed that frailty affects multiple domains of functioning. These include gait and mobility, balance, muscle strength, motor processing, cognition, nutrition (often operationalized as nutritional status or weight change), endurance (including feelings of fatigue and exhaustion), and physical activity.
Frailty is common in older adults (>65y), but different operationalization of frailty status results in widely differing prevalences between studies. In a recent systematic review, [10] the weighted prevalence was 9.9% for physical frailty and 13.6% for the broad definition of frailty. The design of effective interventions to prevent or delay functional decline and disability in older persons is a public health priority. Most likely to benefit from such interventions are community-dwelling frail individuals, without disability or with only early disability, and who are at high risk of becoming functionally dependent. [11] Frail individuals who are institutionalized or hospitalized present a more deteriorated health status and functioning [12] and may need different types of interventions to prevent or minimize complications.
The benefits of exercise in delaying physical dependence in an elderly population have long been recognized, [13, 14] and randomized controlled trials [15, 16] have shown promising early results of physical exercise. Exercise seems to be beneficial in improving physical functions, such as sit-to-stand performance, balance, agility, and ambulation, in older adults. [17–19] Although there are 6 systematic reviews [2, 20–24] exploring the benefits of exercise in frail older adults, a definite conclusion has not yet been reached. Four of the reviews [20, 22–24] applied a very broad definition of frailty that included both nonfrail and prefrail participants. The other 2 reviews [2, 21] applied consistent definitions of frailty but need to be updated with studies published recently in community-dwelling populations. The most recent reviews [23, 24] did not identify some of the studies included in the present review, and both also included noneperformance-based measures as main outcomes.
This systematic review aims to integrate the most current evidence on the effect of exercise interventions on improving performancebased measures of physical function and markers of physical frailty in community-dwelling older people defined as frail according to physical function and physical difficulties in ADL. Specifically, we aimed to (1) examine the effectiveness of exercise compared with control interventions; (2) determine which exercise modalities are most effective; and (3) determine whether there are adverse effects within the exercise interventions.
Discussion
This systematic review has identified the available evidence on the effect of exercise in frail elderly people. When compared with control interventions, exercise has shown to improve gait speed and the SPPB in the frail elderly.
Results are inconclusive for endurance outcomes, and no consistent effect was observed on balance and functional status. The evidence comparing different modalities of exercise is scarce, and it is not possible to pinpoint which exercise characteristics (type, frequency, intensity, duration, setting, combinations) are most effective. Most of the trials included in the review have an unclear or a high risk of bias in their results.
The strong points of this project are as follows: (1) its specific focus on a well-defined population (community-dwelling frail elderly excluding prefrail individuals); (2) its restrictive inclusion of RCTs; (3) the inclusiveness of all types of physical activity interventions and comparisons; and (4) the robust outcomes assessed (performance outcomes), which are relevant indicators of disability for rehabilitation and geriatric specialists. We have focused on frail older adults without dementia and dependency, because this is a population in whom prevention of disability through physical activity is likely. For this reason we have excluded hospitalized and institutionalized individuals, more likely to be dependent or in an unstable clinical condition, and in whom prevention of disability requires further attention. Prefrail individuals were also excluded because different types of exercise programs should be applied.
There are several systematic reviews published on the benefits of physical activity in older adults; however, to our knowledge, there are only 6 systematic reviews [2, 20-24] published specifically on the benefits of exercise in frail older adults.
Our review provides an up-to-date search and quantifies the effect of exercise on different performance parameters through meta-analysis. Without regular updates, systematic reviews become outdated quickly, especially in areas of science with many active researchers. [66] Of the 6 previous systematic reviews, only 222,24 performed a meta-analysis. De Vries et al [24] could not use weighted MDs in their analysis because of the large variation and the large number of studies that did not report sufficient data; therefore, some of the analysis was based on only a few studies and small samples, resulting in inconclusive CIs. Chou et al [22] also performed a meta-analysis but used a broad definition of frailty that could have included nonfrail and prefrail participants.
Chin A Paw et al [2] examined the effect of exercise on the functional ability of frail older adults. They included all studies that were published between 1995 and 2007, considering any setting and using at least 1 performance-based measure of physical function. No standardized definition of frail was considered, and the included trials presented a variable range of functional abilities. From a qualitative assessment of the trials, the authors concluded that regular exercise training (resistance and multicomponent training) could improve functional outcomes in this population, although more high-quality studies were needed.
Daniels et al [20] examined the effect of any type of intervention on disability in community-dwelling, physically frail older adults. The review included studies verifying at least 1 of the frailty indicators described by Ferrucci et al [11] to identify their participants as frail but focused solely on the outcome disability. Since frailty is thought to be caused by multisystem reduction, the presence of only 1 frailty indicator does not necessarily warrant that participants were frail. With our more strict frailty criteria, only 515, [30, 34, 36, 62] of the 10 studies in Daniels were included in our review. The authors suggested that multicomponent exercise training reduced disability impact, especially in moderately frail people. Nevertheless, the subset of trials verifying our more strict frailty criteria1 [5, 30, 34, 36, 62] showed conflicting results with regard to prevention of disability, and this result is in agreement with the uncertainty identified in our review and in a more general overview. [21] Particularly relevant is that the only included trial [36] that focused on maintaining and improving ADL in communitydwelling frail individuals failed to show a significant effect of exercise on a disability score.
In a qualitative overview, Theou et al [21] examined the effectiveness of current exercise interventions for the management of frailty. The authors included frail subjects who were community dwelling, in retirement homes and mixed settings, in the hospital, and in long-term care. The authors found that only 3 trials used a validated definition of frailty to categorize participants, while the rest of the trials either used a nonvalidated definition or did not include an operational definition of frailty. This key finding that limits the applicability of its results shows the urgent need for a clear and widely accepted definition of frailty. Despite these limitations, the authors pointed out some characteristics of exercise programs that seemed to show superior outcomes: multicomponent training with a duration of ≥5 months and performed 3 times per week for 30 to 45 minutes per session. Nevertheless, the applicability of these conclusions is limited given the broad spectrum of participants’ settings and interventions considered, the limitations in frailty definition observed, and the qualitative nature of the comparisons performed. Further evidence from specific randomized trials or providing a meta-analysis is necessary to confirm these conclusions.
Chou [22] performed a meta-analysis that aimed to determine the effect of exercise on the physical function, ADL, and quality of life of frail older adults living in the community or institutionalized. Their inclusion criterion for frailty was based on the Fried Frailty Index, Speechley and Tinetti’s criteria, and the Falls Efficacy Scale, with a very broad perspective that could have included nonfrail or prefrail participants as well as dependent participants who are past the frailty predisability stage. Regardless of including studies published between 2001 and June 2010, they did not include most trials in Theou’s review. [21] The results of their meta-analysis on community and noncommunity trials agree with our findings, showing a significant benefit of exercise in gait speed (their results show an improvement of .07m/s, and our results show an improvement of .06m/s) and BBS, but also great heterogeneity in results for the TUG test and performance in ADL.
De Vries et al [24] also performed a meta-analysis that aimed to assess the effects of physical exercise therapy on physical functioning, mobility, physical activity, and quality of life. Metaanalysis limitations of this trial have been previously discussed. Their inclusion criterion for frailty was based on the presence of mobility problems, physical disability, multimorbidity, or a combination of these, so that nonfrail or prefrail participants could have been included. They found that physical exercise therapy had a positive effect on mobility and physical functioning. Highintensity exercise interventions seem to be more effective in improving physical functioning than low-intensity exercise interventions.
Cadore et al [23] aimed to recommend training strategies that improve the functional capacity in physically frail older adults, focusing specially on supervised exercise programs that improve muscle strength, fall risk, balance, and gait ability. They showed that multicomponent exercise intervention seemed to be the best strategy to improve the rate of falls, gait ability, balance, and strength performance in physically frail older individuals. They included studies that defined subjects as prefrail and mild-tomoderate frail, and there were no restriction to RCTs.
Our systematic review is in agreement with the systematic reviews cited in that the most studied exercise protocol for frail older adults is a multicomponent training. We have found moderate evidence to support exercise training for improving gait speed and combined performance measures such as SPPB, in line with other authors, [22] but we have found the evidence to be inconclusive regarding the effect of exercise training for improving functional mobility or balance, in contrast to other reviews. [20, 22]
In our systematic review, exercise has shown to improve gait speed and performance in the frail elderly, which is similar to Chou’s findings. [22] Gait speed slower than .60m/s was a common feature in the frail older adults. [67] Additionally, slowed gait speed in the older adult population has been related to an increased risk for falls, [68] which, in turn, often leads to a loss of independent living and to institutionalization. As an outcome measure, gait speed has been shown to be a predictor of functional decline, nursing home placement, and mortality. [69] Specifically, a decrease in gait speed of 0.1m/s has been associated with a 10% decrease in the ability to perform instrumental ADL. [70] Reduced muscle strength or poor balance results in a decrease in gait speed. Exercise training has shown to increase gait speed; thus, frail older adults might improve in ambulation and require less dependence and assistance in performing ADL. Clinical practice guidelines explicitly recommend lower limb strength exercises and balance training to prevent falls. Gait speed and performance should also be considered. [71]
Improvements in balance and functional mobility might be linked to the exercise program characteristics. Despite the lack of clear evidence of the effect of exercise on ADL, there is an argument for task-oriented or functional practice. Previous studies [49, 72] have shown the importance of the exercise being task specific if functional ability is to be improved. The duration of training has also been suggested to be an important contributing factor to the retention of neuromuscular adaptations once training has ended, [73] so longer-duration programs might be recommended.
Some authors argue that the number of adverse events is minimal and rarely life threatening, while the gains of regular exercise clearly outweigh the risks. [15, 42, 44, 49, 51, 52, 56] However, depending on the exercise type, we have found that some important adverse events have been detected, such as fractures or falls. Soreness had been reported as an adverse effect in different trials [52]; however, soreness is a normal consequence of the training process in this population. Therefore, exercise programs should be well designed, and conducted and monitored by well-trained physiotherapists and physical activity specialists. Moreover, trials should systematically report adverse effects (eg, type, when does it appear and disappear, its severity, and whether it causes a hospitalization). This register could allow future assessments on the risk-benefit of the intervention.
While more research is still needed, most evidence shows that regular physical activity or exercise is beneficial for older adults who are frail or at high risk of frailty. Rehabilitation and physical activity specialists should recommend regular physical activity or exercise training to frail older adults as a means to modify frailty and its adverse outcomes. [74] However, the exercise recommendations for a healthy older adult will likely be different from those targeting frail older adults. Specifically, frail older adults may need functional-based exercise programs with shorter-duration sessions compared with healthy older adults. Physical activity programs linked to local community facilities offering exercise programs for older adults could offer some advantages over homebased programs, facilitating the continuity of a functional-based exercise program linked or not to social activities, but they have other disadvantages in terms of costs, difficulties in transport and comfort, and preferences of users.
With increasing age, there is a well-described decline in voluntary physical activity leading to an increase risk of frailty. [74] In the present systematic review, we have restricted the inclusion criteria to individuals older than 65 years. Liu and Fielding [75] reviewed the literature investigating the utility of aerobic and resistance exercise training as an intervention for frailty in older adults. The authors concluded that gains of regular exercise clearly outweigh its risks (mainly musculoskeletal complaints, rare cases of falls and cardiovascular risks) if the exercise is appropriately designed. According to our results, there is little evidence to guide interventions to prevent or reduce functional mobility and mobility-related disability in frail older people. The optimal intervention to improve these parameters in daily situations remains unclear. Studies should also follow Consolidated Standards of Reporting Trials (CONSORT) recommendations for nonpharmacologic trials [76] to report risk of bias with a total transparency, and make effective interventions reproducible in the clinical practice.
Moreover, several related areas need further investigation. Adherence to an exercise regimen is necessary to observe beneficial effects, and strategies to increase adherence need to be developed in order to effectively implement exercise as a treatment modality on a wide scale. Also, more studies should assess the sustainability of the effects of exercise. In future studies, researchers should also assess whether significant results translate into significant benefits in clinical practice.
Study limitations
Regarding the project’s limitations, one common finding in the present review is the variability in participant and intervention characteristics, and outcome measures used across studies, similar to previous reviews. Given the multisystem nature of frailty, this variability is to be expected, since multicomponent interventions need to be proposed to affect different indicators of frailty, which will need to be assessed with different outcome measures. Nevertheless, this great heterogeneity hinders the ability to draw conclusions about the appropriate design of the exercise program and, to some extent, the ability to quantify the effect of exercise interventions. Additional limitations of the project are the sample sizes and the risk of bias of the trials included in the review, which limit the strength of the conclusions drawn. In the future, it would be desirable to have larger trials with more rigorous methodology conducted to provide more robust evidence on this topic.
Conclusions
Exercise has some benefits in frail older people, although uncertainty still exists with regard to which exercise characteristics (type, frequency, intensity, duration, setting, combinations) are most effective. When compared with control interventions, exercise has shown to improve gait speed and the Short Physical Performance Battery (SPPB) in the frail elderly. However, results are inconclusive for endurance outcomes, and no consistent effect was observed on balance and functional mobility.
Some aspects to be taken into account for future research are the need for larger trials with more rigorous methodology, focusing on a well-defined population of community-dwelling frail elderly. Such trials should test the sustainability over time of the effects of physical activity interventions, particularly task-oriented or functional practice programs, incorporating strategies to increase adherence and assessing performance outcomes in the medium and long-term. Finally, despite significant work over the past decade, a clear consensus definition of frailty does not emerge from the literature. [3] Important areas for further research include whether disability should be considered a component or an outcome of frailty. A consensus on what is frailty and the criteria to be applied in clinical practice will guide the research and the practice recommendations to clearly defined, homogeneous populations.
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