Background
Worldwide, the number of people over 60 years is growing faster than any other age group and expected to grow from 688 million in 2006 to almost 2 billion by 2050 [
1]. The main reasons for this substantial demographic change are higher life expectancy and declining birth rates [
2]. This future increase in the proportion of older adults is important from a public health perspective [
3]. Aging is generally associated with progressive decline in physical and psychological health [
4,
5], increased risk of disability and dependency [
4], as well as an increase in the number of comorbidities [
6]. This decrease in health status is mainly responsible for one of the most common and serious public health problems, namely falls. Over 33% of community-dwelling people aged over 65 years fall at least once a year, and of those 50% will have recurrent falls [
7,
8]. With increasing age, the rate of falls can increase up to 60% [
7,
9]. Older adults suffering from cognitive decline may fall twice as often compared to their healthy counterparts [
10], while institutionalized older adults in nursing homes or old people’s homes fall even more often [
11].
Despite frequent falling in older adults, only one in five falls requires medical attention while less than 10% lead to a fracture [
12]. However, in terms of morbidity and mortality, injurious falls have serious consequences of which the hip fracture is the most feared one [
13]. Hip fractures often affect functionality and autonomy of older adults [
14], and are associated with an overall mortality of 22% to 29% one year after injury [
15]. In this context, 27% of older adults require a walking aid one year after a hip fracture surgery [
16]. Despite rehabilitation, many individuals do not regain the level of functional performance they had before the fracture [
14] which is why fall prevention is important.
Detection of fall risk factors is essential to implement effective and specifically tailored fall prevention strategies [
17]. Some fall risk factors are irreversible while others are potentially modifiable with appropriate interventions [
18,
19]. Regularly conducted objective, reliable and valid fall risk assessment protocols can assist in identifying individuals at risk to make recommendations and optimize prevention strategies [
20]. Three of the most common modifiable intrinsic (subject-related) fall risk factors are muscle weakness (relative risk ratio / odds ratio 4.4), balance deficits (relative risk ratio / odds ratio 2.9), and gait instabilities (relative risk ratio / odds ratio 2.9) [
9,
19,
21]. These intrinsic risk factors may be modified by exercise referred to as structured, planned and repetitive physical activities in community-based organized exercise programs [
22,
23].
Balance is important for maintaining postural equilibrium and thus for the avoidance of falls. Aging may affect central nervous system (i.e., changes in brain volume) and neuromuscular system properties (i.e., loss of sensory and motor neurons) leading to deficits in balance and gait performance [
24]. According to Shumway-Cook and Woollacott [
25] balance can be subdivided into static / dynamic steady-state (i.e., maintaining a steady position in sitting, standing and walking), proactive (i.e., anticipation of a predicted disturbance), and reactive (i.e., compensation of a disturbance) balance [
26,
27]. Recently, Muehlbauer et al. [
26] were able to show that there is no significant association between measures of steady-state, proactive, and reactive balance in healthy older adults. Thus, for testing and training purposes, balance tests and exercises should target all three domains separately and additionally include dual or multi tasks situations [
26], given that multi-tasking is required for the performance of many activities of daily living (ADL, e.g., walking downstairs while talking on the phone) [
28,
29]. Furthermore, specific balance exercises may help to counteract balance deficits and gait instabilities by reducing the risk of falls in older adults [
30‐
33].
Besides balance, muscle strength / power is required for the successful performance of ADL [
26]. General causes of age-related skeletal muscle mass loss (i.e., sarcopenia) are manifold (e.g., cellular, neural, metabolic, hormonal contributors) [
5,
34,
35]. For the diagnosis of age-related sarcopenia the European Working Group on Sarcopenia in Older People (EWGSOP) recommends using the criteria low muscle mass plus either low muscle strength or low physical performance measured by gait velocity (≤80 cm/s), grip strength and muscle mass [
36]. Humans loose approximately 20% to 30% of their skeletal muscle mass between young adulthood and 80 years of age [
37]. This loss in muscle fibre size and number predominantly occurs in type II muscle fibers which lead to a more rapid decline in muscle power compared to overall muscle strength [
38]. This is detrimental because muscle power is an important prerequisite for quick postural reactions in response to external perturbations [
39]. Older adults often use the hip or step strategy when balance is threatened [
7,
32]. A decrease in muscle power would delay such postural reactions to external perturbations [
40,
41], probably leading to a loss of balance [
42] and ultimately resulting in a fall [
7].
Based on a thorough fall-risk assessment, specifically tailored balance and resistance training programs can be developed which have the potential to improve important intrinsic fall-risk factors like deficits in muscle strength / power and balance performance [
27]. For fall prevention, exercises for the promotion of static / dynamic steady-state, proactive and reactive balance should be trained complementarily [
43]. Progression during training can be achieved by reducing the base of support (e.g., bipedal, step, tandem, monopedal stance) and by diminishing the sensory input (e.g., exercises with eyes opened / closed; exercises on stable / unstable surfaces) [
21,
44]. Additionally, resistance training with a focus on muscle strength / power for the lower extremities and the trunk muscles [
45] seems essential for counteracting intrinsic fall risk factors (i.e., muscle weakness) in older adults.
During the past decades, many fall prevention interventions have proven a positive effect of exercise on intrinsic fall risk factors [
12]. Despite substantial evidence, these programs have not been sufficiently implemented into clinical practice [
46]. To reduce the burden of falls in older adults, easy-to-administer fall prevention programs need to be developed and implemented nationwide. However, lack of skilled people, inadequate communication between researchers, policy makers and clinicians, and health system barriers including inadequate financial resources hinder the implementation of new research evidence into practice [
46,
47]. Besides a lack of evidence about how fall prevention can be incorporated into community services [
48], there is hardly any data available regarding dose–response relationships for optimal exercise for fall prevention. Hence, the Swiss Council for Accident Prevention (bfu) convened an international expert panel (n = 8) consisting of geriatricians, physiotherapists, and health, sports, exercise, accident and fall prevention scientists to conceptualize optimal resistance and balance training programs for fall prevention in older adults. The professional knowledge of the expert panel, the framework of the Manual for Falls Prevention Classification System from the Prevention of Falls Network Europe (ProFaNE) and recent state-of-the-art research, especially in a Swiss context, built the basis for the production of a cost-free practice guide open to the public (available in German or French:
http://www.stuerze.bfu.ch) [
12,
47,
49].
The proposed trial presented in this article will investigate the effects of a fall prevention exercise program developed by an expert panel on intrinsic fall risk factors (i.e., balance, strength / power), body composition, cognitive function, psychosocial well-being, and falls-self efficacy. The applied research tools will allow diagnosis of sarcopenia according to the EWGSOP guidelines. Thus, we will be able to evaluate prevalence of sarcopenia in our participants, and conduct sensitivity and specificity analysis for the strength / power assessments including their cut-offs. To facilitate transfer into clinical practice, simple clinical tests for each instrumented test will be provided to alleviate fall risk assessment and exercise prescription adjustment. In addition to an easy implementation into practice, this will allow cross-validation of the applied research instruments (clinical vs. instrumented). Further, this work may help to promote the protocol of the expert panel and the rationale behind the practice guide to people with English as their native language. We hypothesize that our training program will positively influence balance, strength / power, body composition as well as cognition, psychosocial well-being, and falls-self efficacy in older community-dwelling people.
Discussion
The nationwide implementation of effective fall prevention exercise programs in industrial countries is limited. The present trial applies and evaluates a public practice guide for balance and strength / power training that may provide a feasible, safe, and effective approach for fall prevention in older adults. In contrast to an epidemiological approach, in this trial, we will conduct an intervention based on three major intrinsic fall risk factors (balance impairments, gait instabilities, and muscle weakness). This will allow the use of several extensive clinical and biomechanical measurement tools for evaluation purposes. The proposed exercises require relatively low supervision and material costs, and offer practical information in terms of training volume, (i.e., type, frequency, duration) and intensity. A major advantage of this intervention compared to earlier fall prevention exercise programs is its broad and cost-free applicability and sustainability for German and French speaking older adults.
The expected effect of our fall prevention exercise program is based on a large recent meta-analysis by Gillespie et al. [
12] who showed that multiple-component group exercise and home-based exercise reduce the rate of falls and fall risk (rate ratio 0.71, 95% confidence interval (CI) 0.63 to 0.82 and risk ratio 0.85, 95%CI 0.76 to 0.96 vs. rate ratio 0.68, 95%CI 0.58 to 0.80 and risk ratio 0.78, 95%CI 0.64 to 0.94). Previous studies showed that combined balance and resistance training may positively affect physical (i.e., balance and strength), mental (i.e., quality of life and fear of falling), and functional performance (i.e., ADL) [
33,
94,
96‐
98]. Uncertainty remains if resistance training alone is sufficient to prevent falls in older adults [
99]. Recent studies reported that especially muscle power exercises with lower loads and faster movement velocities improve ADL and therefore may be superior compared to traditional progressive resistance training [
4,
21,
39,
99‐
101]. In contrast, balance exercises are recommended for all older adults who had a fall [
8], however, there is hardly any evidence about training load, volume, and frequency [
21].
The current trial will add valuable information to the knowledge of dose–response-relations for exercise in older adults. Particularly the use of two different intervention arms (extensive supervised group exercise program vs. short home-based exercise program) will give some indication of the minimal amount of exercise needed to stimulate physical performance adaptations. If the short version of the program (3 times per week for 30 min.) will prove to be effective, this may lower the barrier for sedentary older adults to take up exercising. If intrinsic fall risk factors can be positively influenced by our proposed intervention regime, future trials will need to investigate any possible effect on fall rate in older adults. Additionally, in this trial, each clinical test will be compared to a gold-standard instrumented test. This cross-validation may facilitate the implementation of easy-to-administer balance and strength / power assessments into practice. Regular simple balance and strength / power assessments are important for training prescription and performance regarding exercise variation and progression. Furthermore, measuring gait velocity, grip strength and muscle mass will allow diagnosis of sarcopenia according to EWGSOP criteria, and may add knowledge to sensitivity and specificity of strength / power test to this important geriatric syndrome.
In summary, this trial will provide insight into the effect of fall prevention exercise applicable for a broad population and setting, both in community and sporting groups and at home. Practitioners, exercise therapists, and instructors will be provided with a feasible, validated exercise routine whose effect on intrinsic fall risk factors is scientifically evaluated. Furthermore, older adults who participate in the present program represent possible multipliers for a broader acceptance of important exercise and health-enhancing measures. Finally, the results of the current trial may help to further develop theories and models explaining balance and resistance training effects in general and particularly in older adults.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
UG, YJG and BP were involved in the development of the fall prevention program. UG was responsible for the grant application for this trial. All authors contributed to the design of the study. UG and YJG wrote the paper, UG and BP will administer the fall prevention program. All authors read, critically revised, and approved the final version of the manuscript.