An Overview of the Cardiorespiratory Hypothesis and Its Potential Contribution to the Care of Neurodegenerative Disease in Africa.

One hypothesis that could explain the beneficial effects of physical exercise on cognitive function is the cardiorespiratory hypothesis. This hypothesis proposes that improved cognitive functioning may be in part a result of the physiological processes that occur after physical exercise such as: Increased cerebral perfusion and regional cerebral blood flow. These processes ensure increased oxygenation and glucose transportation to the brain, which together can improve cognitive function. The objective of this narrative review is to examine the contribution of this hypothesis in the care of African older adults with neurodegenerative conditions (i.e., dementia (Alzheimer's disease)) or with mild cognitive impairments. Although studies in developed countries have examined people of African descent (i.e., with African Americans), only the limited findings presented in this review reflect how these conditions are also important for the African continent. This review revealed that no studies have examined the effects of cardiorespiratory fitness on neurodegenerative disease in Africa. African nations, like many other developing countries, have an aging population that is growing and will face an increased risk of neurodegenerative declines. It is therefore imperative that new research projects be developed to explore the role of the cardiorespiratory fitness in neurodegenerative disease prevention in African nations.

Motor imagery practice may compensate for the slowdown of sensorimotor processes induced by short-term upper-limb immobilization.

Recently, it has been demonstrated that sensorimotor representations are quickly updated following a brief period of limb non-use. The present study examined the potential of motor imagery practice (MIP) and investigated the role of motor imagery instructions (kinesthetic vs. visual imagery) to counteract the functional impairment induced by sensorimotor restriction. The participants were divided into four groups. Three groups wore a splint on their left hand for 24 h. Prior to the splint removal, two of the three groups performed 15 min of MIP, with kinesthetic or visual modalities (KinMIP and VisMIP groups, respectively). The third group did not practice motor imagery (NoMIP group). Immediately after the splint removal, the participants were assessed using a hand laterality task known for evaluating sensorimotor processes. A fourth group served as the control (i.e., without immobilization and MIP). The main results showed slower left-hand response times for the immobilized NoMIP group compared with the controls. Importantly, faster response times for the left-hand stimuli appeared for the KinMIP groups only compared with the NoMIP group. No difference between the four groups was observed for the right-hand stimuli. Overall, these results highlighted the somatotopic effect of limb non-use on the efficiency of sensorimotor processes. Importantly, the slowdown of the sensorimotor processes induced by 24 h of sensorimotor deprivation may be counteracted by a kinesthetic MIP, whereas no beneficial effect appeared with visual imagery. We discuss the importance of imagery modalities for sensorimotor reactivation.

Effects of Physical Activity on Physical and Mental Health of Older Adults Living in Care Settings: A Systematic Review of Meta-Analyses.

Previous studies included in meta-analyses have highlighted the effects of physical activity on the physical and psychological health of older adults living in care settings. We conducted a systematic review of meta-analyses, of institutionalized older adults, to evaluate and conduct a narrative synthesis of the results of these meta-analyses. A literature search was conducted in three databases (PubMed, Web of Science, and Cochrane Library) until 22 March 2023. After screening the identified articles with the PRISMA criteria filters, we included 11 meta-analyses in this systematic review. Higgins' (2013) assessment tool of the meta-analyses demonstrates that the studies were of good quality although future meta-analyses need to provide more information on the treatment of missing data. A summary of the results of these meta-analyses shows that physical activity reduces the rate of falls, mobility issues, functional dependence, and depression, and improves health status. Future studies need to focus on new ways to promote and adapt physical activities to increase the participation of older adults in care settings.

SnacktivityTM, Giant Games and Immersive Virtual Reality Exercises: A Rapid Narrative Review of These New Physical Activity Practices among Older People Living in Nursing Homes and Long-Term Care Facilities.

In developed countries, the increasing number of older adults raises many public health challenges. Physical activity can enable healthy aging, as it is beneficial for both mental and physical health. Despite this, not all older adults engage in physical activity or have access to it. To counteract this, new physical practices such as SnacktivityTM, giant games and immersive virtual reality exercises are being developed. The main objective of this rapid narrative review is to summarize the effects of SnacktivityTM, giant games and immersive Virtual Reality (VR) exercise among older adults living in nursing homes and long-term care facilities. A scientific review was performed using the search engines PubMed, PsycInfo and Web of Science on 7 July 2022. Fifty-nine items are identified in total, and five items are included in the literature review. Synthesis of the studies shows that immersive virtual reality and giant games improve the motivation and enjoyment of older adults and are beneficial for their functional abilities. Furthermore, no interventional studies have tested the effect of SnacktivityTM in older adults. This review suggests that future studies should be conducted to further explore the effects of these new physical activity practices in older adults living in nursing homes or long-term care facilities.

Is there a relationship between cardiorespiratory fitness and executive performance as function of mental workload in young adults?

In the current study, we have decided to investigate the relationship between cardiorespiratory fitness and executive functions in young adults as a function of mental workload. To achieve our objectives, we have solicited 29 young adults (18-25 years; 12 women) who have first realized the Random Number Generation (RNG) task with two levels of complexity. After each level of complexity, the participants were asked to report on their perceived difficulty. Secondly, participants performed the RABIT® test, during which oxygen consumption was measured through the Metamax 3B-R2. The results showed that executive performance and perceived difficulty deteriorate with increasing task complexity. Additionally, oxygen consumption increased significantly to reach a peak during the hardest phase of the RABIT® test. Finally, as in previous studies, we could not observe a correlation between cardiorespiratory fitness and executive functions. Our findings support the lack of a direct relationship between cardiorespiratory fitness and executive functions. Future studies should explore the relationship between the composite measure of executive function, hemodynamic activity, and cardiorespiratory fitness in healthy youth and their peers with cardiovascular disease. This will examine an indirect effect of Cardiorespiratory fitness (CRF) on Executive functions (EFs) through brain activity.

Load-Dependent Prefrontal Cortex Activation Assessed by Continuous-Wave Near-Infrared Spectroscopy during Two Executive Tasks with Three Cognitive Loads in Young Adults.

The present study examined the evolution of the behavioral performance, subjectively perceived difficulty, and hemodynamic activity of the prefrontal cortex as a function of cognitive load during two different cognitive tasks tapping executive functions. Additionally, it investigated the relationships between these behavioral, subjective, and neuroimaging data. Nineteen right-handed young adults (18-22 years) were scanned using continuous-wave functional near-infrared spectroscopy during the performance of n-back and random number generation tasks in three cognitive load conditions. Four emitter and four receptor optodes were fixed bilaterally over the ventrolateral and dorsolateral prefrontal cortices to record the hemodynamic changes. A self-reported scale measured the perceived difficulty. The findings of this study showed that an increasing cognitive load deteriorated the behavioral performance and increased the perceived difficulty. The hemodynamic activity increased parametrically for the three cognitive loads of the random number generation task and in a two-back and three-back compared to a one-back condition. In addition, the hemodynamic activity was specifically greater in the ventrolateral prefrontal cortex than in the dorsolateral prefrontal cortex for both cognitive tasks (random number generation and n-back tasks). Finally, the results highlighted some links between cerebral oxygenation and the behavioral performance, but not the subjectively perceived difficulty. Our results suggest that cognitive load affects the executive performance and perceived difficulty and that fNIRS can be used to specify the prefrontal cortex's implications for executive tasks involving inhibition and working memory updating.

Effects of Chronic Physical Exercise or Multicomponent Exercise Programs on the Mental Health and Cognition of Older Adults Living in a Nursing Home: A Systematic Review of Studies From the Past 10 Years.

Some nursing homes for the elderly provide holistic care that integrates several interventions, including physical exercise. The aim of this systematic review is to summarize the effects of physical exercise or multicomponent exercise programs on the mental health (wellbeing, anxiety and depression) and cognitive functions of older adults with/without dementia who live in a nursing home and do/do not require wheelchair assistance. To this end, PubMed, PsycInfo and Web of Science are using to identify clinical trials and randomized controlled studies conducted during the period January 2011 to December 2021 to examine the progression of research in this field over the past ten years. In total, 2597 articles are identifying and 21 are including in the systematic review. After selecting articles according to the PRISMA standards, the data extraction and methodological quality assessment of the eligible studies are performing individually by two reviewers and then pooled together. The synthesis of the studies shows that physical exercise or multicomponent exercise programs have a beneficial effect on mental health and cognitive functions. However, this effect is more common among older adults without dementia, compared to their counterparts who have dementia or use wheelchairs. The explanatory mechanisms, lack of benefits from physical exercise and the need to standardize methods are discussing in this regard. Finally, future studies must examine the effects of an innovative and adaptive physical activity program on the mental health and cognitive functions of older adults living in nursing homes.

Mini-Review of Studies Testing the Cardiorespiratory Hypothesis With Near-Infrared Spectroscopy (NIRS): Overview and Perspectives.

The cardiorespiratory hypothesis (CH) is one of the hypotheses used by researchers to explain the relationship between cardiorespiratory fitness and cognitive performance during executive functions. Despite the indubitable beneficial effect of training on brain blood flow and function that may explain the link between physical fitness and cognition and the recognition of the near-infrared spectroscopy (NIRS) as a reliable tool for measuring brain oxygenation, few studies investigated the CH with NIRS. It is still not well understood whether an increase in brain flow by training is translated into an increase in cerebral oxygenation. Thus, the objective of this mini-review was to summarize main results of studies that investigated the CH using the NIRS and to propose future research directions.

Are Barriers the Same Whether I Want to Start or Maintain Exercise? A Narrative Review on Healthy Older Adults.

To help older adults begin or adhere to regular physical exercise, several studies have endeavored to identify barriers to active behavior. However, there is a lack of information about barriers for active older people. In addition, most of the reviews of the literature compare only active people to inactive or sedentary people without examining in detail the barriers with respect to the degree of commitment to behavioral change. Finally, there is no consistency in the results of studies investigating the effects of barriers on the relationship between stages of change and exercise behavior. The first aim of this narrative review is to compare barriers that affect exercise stages of change from those that affect levels of exercise behavior in a healthy older population and the factors that can lead to relapse or dropout; the second aim is to identify the extent to which barriers hinder the relationships between stages of change and exercise behaviors. The results showed that barriers are well identified in sedentary people and in the first two stages of change (pre-contemplation and contemplation) compared to active seniors and other stages of change (preparation, action and maintenance). Consistency between the formulations of the different stages in comparison with the transtheoretical model and the definition of barriers and the limitations of measuring physical activity in the different studies are discussed. Finally, novel perspectives of research are proposed to address the flaws in the reviewed studies.

Working Memory, Cognitive Load andCardiorespiratory Fitness: Testing the CRUNCHModel with Near-Infrared Spectroscopy.

The present study aimed to examine the effects of chronological age and cardiorespiratory fitness (CRF) on cognitive performance and prefrontal cortex activity, and to test the compensation-related utilization of neural circuits hypothesis (CRUNCH). A total of 19 young adults (18⁻22 years) and 37 older ones (60⁻77 years) with a high or low CRF level were recruited to perform a working memory updating task under three different cognitive load conditions. Prefrontal cortex hemodynamic responses were continuously recorded using functional near-infrared spectroscopy, and behavioral performances and perceived difficulty were measured. Results showed that chronological age had deleterious effects on both cognitive performance and prefrontal cortex activation under a higher cognitive load. In older adults, however, higher levels of CRF were related to increased bilateral prefrontal cortex activation patterns that allowed them to sustain better cognitive performances, especially under the highest cognitive load. These results are discussed in the light of the neurocognitive CRUNCH model.

Selective impairment of sensorimotor representations following short-term upper-limb immobilization.

In the present experiment, we examined whether short-term upper-limb immobilization would selectively affect the representation of the immobilized limb (using a hand laterality task) or whether the effect of immobilization would extend to another body part (using a foot laterality task). A rigid splint placed on the participants' left hand was used for immobilization. A control group did not undergo the immobilization procedure. We compared the participants' performances on the hand and foot laterality tasks before (T1) and after (T2) a 48-hour delay, corresponding to the immobilization period. For controls, response time analysis indicated a benefit of task repetition for the recognition of both hand and foot images. For the immobilized group, a slowdown of performance appeared in T2 for hand images, but not for foot images. The reduced benefit of task repetition following left-hand immobilization appeared for both the immobilized and non-immobilized hand images. These findings revealed that the general cognitive representation of upper-limb movements is affected by the decrease in input/output signal processing due to the left-hand immobilization, while the cognitive representation of lower-limb movements is not.