No abstract

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.

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.

In the present experiment, we examined whether short-term upper-limb immobilisation would selectively affect the representation of the immobilised limb (using a hand laterality task) or if the effect of immobilisation would extend to another body part (using a foot laterality task). A rigid splint placed on the participants' left hand was used for immobilisation. A control group did not undergo the immobilisation procedure. We compared the participants' performances on the hand and foot laterality tasks before (T 1 ) and after (T 2 ) a 48-hour delay, corresponding to the immobilisation period. For controls, response time analysis indicated a benefit of task repetition for the recognition of both hand and foot images. For the immobilised group, a slowdown of performance appeared in T 2 for hand images, but not for foot images. The reduced benefit of task repetition following left-hand immobilisation appeared for both the immobilised and non-immobilised 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 immobilisation, while the cognitive representation of lower-limb movements is not.

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.

Using continuous-wave near-infrared spectroscopy (NIRS), this study compared three different methods, namely the slope method (SM), the amplitude method (AM), and the area under the curve (AUC) method to determine the variations of intramuscular oxygenation level as a function of workload. Ten right-handed subjects (22±4 years) performed one isometric contraction at each of three different workloads (30 %, 50 % and 90 % of maximal voluntary strength) during a period of twenty seconds. Changes in oxyhemoglobin (Δ[HbO2]) and deoxyhemoglobin (Δ[HHb]) concentrations in the superficial flexor of fingers were recorded using continuous-wave NIRS. The results showed a strong consistency between the three methods, with standardized Cronbach alphas of 0.87 for Δ[HHb] and 0.95 for Δ[HbO2]. No significant differences between the three methods were observed concerning Δ[HHb] as a function of workload. However, only the SM showed sufficient sensitivity to detect a significant decrease in Δ[HbO2] between 30 % and 50 % of workload (p<0.01). Among these three methods, the SM appeared to be the only method that was well adapted and sensitive enough to determine slight changes in Δ[HbO2]. Theoretical and methodological implications of these results are discussed.

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.

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.