Impact of Physical Activity on Physical and Cognition Function among Community-Living Older Adults

Abstract

The aging population presents unique challenges to healthcare systems worldwide, particularly in terms of maintaining physical function and cognitive abilities in old age. Physical activity (PA) is emerging as a potent intervention to enhance the well-being and functional independence of older individuals. The current review chapter will focus on the effect of PA on physical and cognitive function to provide comprehensive understanding of the interplay among community-dwelling older adults. The review (1) overviews the positive impact of PA on physical functions, including muscle strength, endurance, balance, and cardiovascular health, elucidating how these benefits contribute to improved mobility and reduced risk of falls among older adults, and (2) explores also how regular PA is associated with the cognitive benefits, including its preventive or delaying effect of cognitive decline, enhancements in memory, attention, executive function, and overall cognitive vitality. It emphasizes the critical role of PA in enhancing the overall capacity on managing daily living of older adults and offers insights into effective strategies for promoting active and healthy aging. These knowledge and insights can also guide healthcare practitioners, policymakers, and researchers in developing and implementing effective strategies to promote PA and support healthy aging in older populations.

1. Introduction

Aging is an inevitable process that every individual undergoes as they progress through life. The global demographic changes show a significant shift that the proportion of older adults (aged 60 and above) steadily increasing [1]. This demographic transition has caused a growing interest in healthy aging and age-related health challenges [2, 3]. This phenomenon is attributed to a combination of factors, including declining birth rates and advancements in healthcare, resulting in extended life expectancies [4]. This review chapter underscores the significant role of PA in enhancing the quality of life and functional independence of community-living older adults, illuminating the pathways through which it positively impacts both physical and cognitive functions. It calls for continued research and targeted interventions to harness the potential of PA as a cornerstone of healthy aging. This perspective sheds light on the following impact of an aging population on our society. The potential impact of an aging population on our society are followings:

1. Healthcare challenges: A significant increase in the older population presents various challenges for healthcare systems worldwide. There is a higher demand for healthcare services, particularly for age-related diseases and conditions such as Alzheimer’s disease, diabetes, and cardiovascular problems.

2. Economic implications: The aging population can also have economic implications. As the older population grows, it may affect economic productivity and labor markets. Governments need to address these challenges to maintain economic stability.

3. Social considerations: An aging population can lead to changes in family structures and caregiving dynamics. The responsibility of caring for elderly family members often falls on the younger generation, impacting their work-life balance and overall well-being.

2. Understanding factors contributing to the increase of older population

Chronological aging refers to the passage of time as measured by one’s date of birth [5], commonly used to determine an individual’s age, wherein each passing year contributes to one’s chronological age. Life expectancy (LE) is an important indicator for measuring the growth of the aging population [6], which is increasing globally as a result of reduced mortality among the older individuals [7]. Another significant factor contributing to the growth of the older population is the decline in birth rates observed in many countries [7, 8], resulting in a phenomenon known as “population aging.” With fewer young people being born, the proportion of older individuals in the population naturally increases. Enhanced healthcare and medical advancements have also played a pivotal role in extending LE [9]. Medical conditions that were once fatal are now manageable or treatable, allowing individuals to lead longer and healthier lives. Improved accessibility to healthcare services and preventive measures has further contributed to this trend [10]. Moreover, economic stability and social welfare programs have provided support for older individuals [11], enabling them to lead more comfortable lives during their later years.

3. Impacts of PA on physical and cognitive function among older population

Physical and cognitive function are two fundamental aspects of an individual’s well-being, influencing their ability to live independently and maintain a high quality of life (M. [12, 13, 14]). Aging-related functional decline can result in numerous health issues, reduced autonomy, decreased independence, and heightened pressure on healthcare systems [15, 16]. Given the importance of physical function and cognition in the lives of older adults, understanding how PA impacts these domains is crucial. The present chapter explores the current body of evidence on the topic, highlighting the potential benefits of regular PA on the physical and cognitive function of older adults.

Muscular strength declines 3% every year, and muscle mass reduces about 2% after 40 [17, 18, 19, 20]. These phenomena of decline in both muscular strength and muscle mass with aging are well-known, and it is important to consider that the cause of this decline may not solely be attributed to the aging process itself but could also be linked to the reduction in PA that typically accompanies the aging process. Reduction in PA accelerated myoatrophy, which causes the loss of muscle mass and eventually lower basal metabolism [21, 22]. These changes lead to surplus energy increases and the accumulation of lipids [23, 24], which may further cause health problems, including higher blood pressure or blood glucose levels [25, 26, 27]. The significance of PA in maintaining our health has been long acknowledged. Regular PA offers numerous benefits, including (1) improving cardiovascular health, (2) enhancing or preserving cognitive and physical function [28, 29], and (3) reducing the risk of cognitive decline and major neurocognitive disorder among older adults [30, 31].

Clear evidences suggest that PA is beneficial for maintaining cognitive function, reducing risk of major neurocognitive disorder, and brain atrophy among older adults [30, 32]. While obesity and overweight were found to increase risk of major neurocognitive disorder [33], brain volumes (total brain tissue volume and gray matter and white matter volumes) are also strongly related to atherosclerosis [34], as well as to vascular risk factors such as systolic and diastolic blood pressure [35] or diabetes [36, 37]. The effect of regular PA and obesity on brain health may reflect lifestyle factors [32] or underlying modulation of neurotrophic and vascular risk factors as demonstrated in clinical and experimental research [38, 39].

4. Impact of PA on mobility and associated cognitive function

Those with low physical performance have a significantly higher risk of future institutionalization and disability onset [40, 41, 42]. While regular PA participation is linked with positive health outcomes, lack of PA has been also associated with increased disability and poor physical function among older adults [43]. Particularly, the mobility disability has been shown its predictive value for future institutionalization, mortality, and disability onset [40, 44]. Therefore, mobility function of older adults is often used as a clinical screening tool for the older population [43]. On the other hand, it is also suggested that those with low cognitive function have a lower mobility function compared with those with normal cognitive function (M. [12, 45, 46]). As the ability to move from one location to another is closely linked to factors such as attention, body coordination, and adaptability to one’s surroundings [12, 47], older adults may need to maintain a higher level of cognitive function in order to sustain their independence in daily life.

5. Cognitive impairment among older adults

It is crucial to prioritize efforts to prevent or postpone cognitive decline in older adults [48]. Nevertheless, a substantial number of major neurocognitive disorder patients also experience damage from other vascular brain diseases, including mini-strokes, which are ranked as the fifth leading cause of death in the United States [49]. Earlier research has suggested that this major neurocognitive disorder could potentially rank as the third leading cause of death for older individuals, trailing only behind heart disease and cancer [50]. Memory problems are typically one of the first signs of cognitive impairment [51]. Some people with more memory problems than normal for their age may also have mild cognitive impairment (MCI), but their symptoms do not interfere with their everyday lives [52]. Movement difficulties and problems with the sense of smell have also been linked to MCI [53, 54].

While the impact of PA on cognitive functions is evident, several limitations need to be considered when interpreting the results. First, most studies had PA data collected close to the time at which cognitive function was assessed or major neurocognitive disorder diagnosed. With the short time intervals between PA and major neurocognitive disorder, it is difficult to determine whether the reported PA acts as a risk factor for cognitive decline or serves as an indicator of incipient disease. Second, most previous studies have examined either the relationship between PA and global cognitive performance or major neurocognitive disorder, but not both simultaneously. Third, studies that investigated the relationship between midlife PA and the risk of major neurocognitive disorder were mixed, and there is limited information on the association between levels of PA earlier in life and brain atrophy among older adults. At last, most studies investigating age-related changes in cerebral volume were cross-sectional and utilized small sample sizes of healthy older individuals or larger samples with all age groups. Further, longitudinal research on the impact of long-term PA on brain health is vital for a comprehensive understanding of these relationships.

While older people with MCI are at greater risk for developing major neurocognitive disorder, some may go back to normal cognition [53]. Researchers are studying biomarkers (biological signs of disease found in brain images, cerebrospinal fluid, and blood) to detect early sign in the brains of people with MCI and people with normal cognition who may be at greater risk for the major neurocognitive disorder [55]. Previous studies indicated that early detection is possible, but more research is needed before these medical techniques are available for the everyday medical practice to diagnose AD [48].

6. Effective PA intervention to prevent functional decline

Numerous exercise intervention studies have demonstrated that exercise improves physical performance in old age [12, 56, 57]. Further, regular PA or exercise also has a positive association with cognitive performance in the short- or long-term period [12, 58, 59]. Among various types of exercise for older adults, resistance exercise is one of the most feasible types of exercise to increase muscle mass and strength [59, 60, 61]. Particularly for the prevention of mobility disability and sarcopenia, the strength training is suggested as the most effective training method for older adults [59, 62, 63], even for those with limited mobility or cardiovascular fitness [64].

Cross-sectional studies have also shown that PA and physical performance are strongly associated with cognitive function [65, 66, 67], while it is possible that the improvement of physical performance by the exercise intervention may vary by baseline cognitive status [12]. Exercise intervention studies have primarily focused on investigating the improvement of physical performance and cognitive function among older adults following the intervention period [12, 13, 56, 62]. The specific findings related to the influence of various types of physical activity on cognitive function are as follows.

1. Engaging in regular aerobic exercises, such as running, swimming, or cycling, has been associated with improved cognitive functions, especially memory and attention, and has been correlated with increased hippocampal volume, contributing to memory enhancement and reduced cognitive decline risk [68, 69, 70].

2. Strength training, such as weightlifting or resistance exercises, has been found to benefit cognitive functions such as attention and memory [71]. Research suggests that resistance training can positively affect cognitive tasks and memory performance [59, 72, 73].

3. Activities, such as dance and coordination exercises, including tai chi, have been associated with improved cognitive functions related to praxis and visuospatial skills. Studies have shown that these activities can positively impact cognitive performance, particularly in the area of visuospatial abilities [74, 75]. Yoga and meditation practices have demonstrated significant benefits for attention and memory, with studies indicating that regular yoga practice can improve cognitive functions, including memory, attention, and processing speed [76, 77].

4. Certain cognitive training programs and brain games have been designed to target specific cognitive functions, including memory, attention, and language. Research suggests that engaging in these activities can lead to improvements in cognitive performance and function [78, 79, 80].

7. Other potentially modifiable risk factors for cognitive decline

Although age is the strongest risk factor for cognitive decline, major neurocognitive disorder may not be an inevitable consequence of aging [81, 82]. Several recent studies have shown that lifestyle-related risk factors, including physical inactivity, tobacco use, unhealthy diets, and harmful use of alcohol, are strongly associated with cognitive impairment and major neurocognitive disorder [83]. Hypertension, diabetes, hypercholesterolemia, obesity, and depression are all associated with an elevated risk of experiencing cognitive decline or developing major neurocognitive disorder [84, 85]. Other potentially modifiable risk factors, such as social isolation and cognitive inactivity, were also linked to the development of major neurocognitive disorder [48]. The risk reduction guidelines for cognitive decline and major neurocognitive disorder from WHO provide evidence-based guidance for a public health response to major neurocognitive disorder. These modifiable risk factors suggest that prevention of cognitive decline or major neurocognitive disorder is possible through a public health approach. Several evidence-based research have investigated whether reducing modifiable risk factors decrease the risk for major neurocognitive disorder [14, 86].

8. Types of intervention to prevent cognitive decline

Cognitive impairment and major neurocognitive disorder are complex, multifactorial disorders, and multi-domain interventions targeting several risk factors and disease mechanisms simultaneously could be needed for optimum preventive effects [85]. Previous prevention trials for cognitive impairment and major neurocognitive disorder have reported positive associations with cognition for PA, cognitive training, or both in smaller and shorter intervention studies [87, 88, 89]. Few prevention trials for cardiovascular disease and type 2 diabetes have emphasized the importance of a multi-domain approach [37, 87]. Multicomponent randomized controlled trials in individuals at risk of major neurocognitive disorder have been also recommended as an effective and feasible approach [85, 90]. Previous findings suggest that a risk factors other than genetics play a role in the development of AD [84]. One of a great deal of interest could be the relationship between cognitive decline and vascular conditions such as heart disease, stroke, and high blood pressure, as well as metabolic conditions, such as diabetes and obesity [91]. In general, a nutritious diet, PA, social engagement, and mentally stimulating pursuits have all been associated with helping people stay healthy as they age [90, 92]. These factors help in reducing the risk of cognitive decline [85]. However, evidence that short-term and single-component PA interventions promote cognitive function and prevent cognitive decline or major neurocognitive disorder in older adults is largely insufficient. Various forms of PA and exercise interventions have provided compelling evidence in countering sedentary habits and encouraging PA. These interventions include the followings (Table 1).

Multimodal intervention programs: Implementing a long-term multicomponent program that combines various types of intervention including PA, cognitive training, social activity, and nutritional and cardiovascular counseling, has been shown to be effective in improving overall fitness, reducing sedentary behavior, and preventing a major neurocognitive disorder [85, 93].

Aerobic exercise programs: Implementing structured aerobic exercise programs, such as walking, jogging, or cycling, has shown significant effectiveness in reducing sedentary behavior and improving overall physical health. These programs are often tailored to individual fitness levels and can be conducted in group settings or individually [94, 95, 96].

Strength training interventions: Incorporating strength training interventions, including resistance exercises and weightlifting, has been found to be effective in promoting muscle strength, improving overall fitness, and combating the negative effects of a sedentary lifestyle, particularly in older adults [97].

Mind–body with flexibility and balance exercise programs: Interventions that integrate mind–body exercises, flexibility, and balance include tai-chi, yoga, and Pilates have demonstrated effectiveness in reducing sedentary behavior and promoting PA, while also providing benefits for mental well-being and stress reduction [74, 75, 77].

Table 1.

Effective types of intervention on cognition for older adults.

9. Impact of preventive intervention in adults with MCI

For cognitive outcomes in adults with MCI, evidence is still insufficient to indicate that PA interventions have a positive effect on cognition [31, 91]. However, these benefits are not consistent across all cognitive domains. This clinical trial proposal tests the efficacy and additive/synergistic effects of an exercise and cognitive training intervention on cognition with other risk factor management (social activity, nutrition, alcohol, and metabolic syndrome) in older adults who are diagnosed with MCI. Exercise and cognitive training are two promising interventions for preventing major neurocognitive disorders. Exercise increases fitness, which, in turn, improves brain structure and function, while cognitive training improves selective neural function intensively [48]. Various studies that tested cognitive training effects have reported discrepant findings due to varying programs [79, 98]. Hence, combined exercise and cognitive training may very well have an additive or synergistic effect on cognition by complementary strengthening of different neural functions. A meta-analysis of randomized controlled trials revealed a moderate effect of PA, with the most significant effect size observed for executive control processes [69, 99]. Optimal cognitive benefits were observed when aerobic training was combined with strength and flexibility training. Those review studies emphasized that a minimum of 30 minutes of PA training for over 6 months appeared necessary to establish stable cognitive effects in older adults. Moreover, the study suggested that engaging in moderate-intensity exercise, with an average duration of 1 hour per session, at least three times per week, could yield more pronounced cognitive and brain effects.

10. Conclusion

The impact of PA and exercise on physical function and cognition among community-living older adults is substantial. Regular PA and exercise have been proven to boost muscular strength, balance, mobility, cognitive function, and overall well-being in older population. The mechanisms underlying the positive impact of PA on physical function and cognition in older adults are multifaceted. Factors, such as increased blood flow to the brain, the release of neurotrophic factors, and reduced inflammation, contribute to these benefits. It is crucial for healthcare professionals, policymakers, and community organizations to facilitate initiatives that promote regular PA among older adults. This includes providing accessible exercise programs, educating about the benefits of PA and exercise, and establishing age-friendly environments. While existing literature highlights the positive relationship between PA, physical function, and cognition, further research is needed to fully understand this complex association. Long-term randomized controlled trials and investigations into the most effective types and intensities of exercise for different older adult populations can offer valuable insights.

Highlighting PA as an essential component of healthy aging is crucial, and continuous research in this area will further inform strategies aimed at improving the lives of older adults globally. As societies age, investing in older adults’ health through PA initiatives will help to promote a healthier and more dynamic future for all.