A Systematic Review on the Cognitive Benefits and Neurophysiological Correlates of Exergaming in Healthy Older Adults

Human aging is associated with structural and functional brain deteriorations and a corresponding cognitive decline. Exergaming (i.e., physically active video-gaming) has been supposed to attenuate age-related brain deteriorations and may even improve cognitive functions in healthy older adults. Effects of exergaming, however, vary largely across studies. Moreover, the underlying neurophysiological mechanisms by which exergaming may affect cognitive and brain function are still poorly understood. Therefore, we systematically reviewed the effects of exergame interventions on cognitive outcomes and neurophysiological correlates in healthy older adults (>60 years). After screening 2709 studies (Cochrane Library, PsycINFO, Pubmed, Scopus), we found 15 eligible studies, four of which comprised neurophysiological measures. Most studies reported within group improvements in exergamers and favorable interaction effects compared to passive controls. Fewer studies found superior effects of exergaming over physically active control groups and, if so, solely for executive functions. Regarding individual cognitive domains, results showed no consistence. Positive effects on neurophysiological outcomes were present in all respective studies. In summary, exergaming seems to be equally or slightly more effective than other physical interventions on cognitive functions in healthy older adults. Tailored interventions using well-considered exergames and intervention designs, however, may result in more distinct effects on cognitive functions

Shedding Light on the Effects of Moderate Acute Exercise on Working Memory Performance in Healthy Older Adults: An fNIRS Study

Numerous studies have reported the beneficial effects of acute exercise on executive functions. Less is known, however, about the effects of exercise on working memory as one subcomponent of executive functions and about its effects on older adults. We investigated the effects of acute moderate-intensity exercise on working memory performance, the respective cortical hemodynamic activation patterns, and the development and persistence of such effects in healthy older adults. Forty-four participants (M: 69.18 years ± 3.92; 21 females) performed a letter 2-back task before and at three time points after (post 15 min, post 30 min, and post 45 min) either listening to an audiobook or exercising (15 min; 50% VO2-peak). Functional near-infrared spectroscopy (fNIRS) was used to assess cortical hemodynamic activation and brain-behavior correlations in the fronto-parietal working memory network. Overall, we found no group differences for working memory performance. However, only within the experimental group, 2-back performance was enhanced 15 min and 45 min post-exercise. Furthermore, 15 min post-exercise frontal activation predicted working memory performance, regardless of group. In sum, our results indicate slight beneficial effects of acute moderate-intensity exercise on working memory performance in healthy older adults. Findings are discussed in light of the cognitive aging process and moderators affecting the exercise-cognition relationship

Inefficient frontal and parietal brain activation during dual-task walking in a virtual environment in older adults

Walking while performing an additional cognitive task (dual-task walking; DT walking) is a common yet highly demanding behavior in daily life. Previous neuroimaging studies have shown that performance declines from single-task (ST) to DT conditions are accompanied by increased prefrontal cortex (PFC) activity. This increment is particularly pronounced in older adults and has been explained either by compensation, dedifferentiation, or inefficient task processing in fronto-parietal circuits. However, there is only limited evidence for the hypothesized fronto-parietal activity changes measured under real-life conditions such as walking. In this study, we therefore assessed brain activity in PFC and parietal lobe (PL), to investigate whether higher PFC activation during DT walking in older adults is related to compensation, dedifferentiation, or neural inefficiency. Fifty-six healthy older adults (69.11 ± 4.19 years, 30 female) completed three tasks (treadmill walking at 1 m/s, Stroop task, Serial 3′s task) under ST and DT conditions (Walking + Stroop, Walking + Serial 3′s), and a baseline standing task. Behavioral outcomes were step time variability (Walking), Balance Integration Score BIS (Stroop), and number of correct calculations S3corr (Serial 3′s). Brain activity was measured using functional near-infrared spectroscopy (fNIRS) over ventrolateral and dorsolateral PFC (vlPFC, dlPFC) and inferior and superior PL (iPL, sPL). Neurophysiological outcome measures were oxygenated (HbO2) and deoxygenated hemoglobin (HbR). Linear mixed models with follow-up estimated marginal means contrasts were applied to investigate region-specific upregulations of brain activation from ST to DT conditions. Furthermore, the relationships of DT-specific activations across all brain regions was analyzed as well as the relationship between changes in brain activation and changes in behavioral performance from ST to DT. Data indicated the expected upregulation from ST to DT and that DT-related upregulation was more pronounced in PFC (particularly in vlPFC) than in PL regions. Activation increases from ST to DT were positively correlated between all brain regions, and higher brain activation changes predicted higher declines in behavioral performance from ST to DT. Results were largely consistent for both DTs (Stroop and Serial 3′s). These findings more likely suggest neural inefficiency and dedifferentiation in PFC and PL rather than fronto-parietal compensation during DT walking in older adults. Findings have implications for interpreting and promoting efficacy of long-term interventions to improve DT walking in older persons

The association of executive functions and physical fitness with cognitive-motor multitasking in a street crossing scenario

Abstract Age-related decline in cognitive-motor multitasking performance has been attributed to declines in executive functions and physical fitness (motor coordinative fitness and cardiovascular fitness). It has been suggested that those cognitive and physical resources strongly depend on lifestyle factors such as long-term regular physical activity and cognitive engagement. Although research suggests that there is covariation between components of executive functions and physical fitness, the interdependence between these components for cognitive-motor multitasking performance is not yet clear. The aim of the study was to examine the contribution and interrelationship between executive functions, motor coordinative fitness, and cardiovascular fitness on street crossing while multitasking. We used the more ecologically valid scenario to obtain results that might be directly transferable to daily life situation. Data from 50 healthy older adults (65–75 years, 17 females, recruited in two different cities in Germany) were analyzed. Participants’ executive functions (composite score including six tests), motor coordinative fitness (composite score including five tests), and cardiovascular fitness (spiroergometry), as well as their street crossing performance while multitasking were assessed. Street crossing was tested under single-task (crossing a two-line road), and multitask conditions (crossing a two-line road while typing numbers on a keypad as simulation of mobile phone use). Street crossing performance was assessed by use of cognitive outcomes (typing, crossing failures) and motor outcomes (stay time, crossing speed). Linear mixed-effects models showed beneficial main effects of executive functions for typing (p = 0.004) and crossing failures (p = 0.023), and a beneficial main effect of motor coordinative fitness for stay time (p = 0.043). Commonality analysis revealed that the proportion of variance commonly explained by executive functions, motor coordinative fitness, and cardiovascular fitness was small for all street crossing outcomes. For typing and crossing failures (cognitive outcomes), the results further showed a higher relative contribution of executive functions compared to motor coordinative fitness and cardiovascular fitness. For stay time (motor outcome), the results correspondingly revealed a higher relative contribution of motor coordinative fitness compared to executive functions and cardiovascular fitness. The findings suggest that during cognitive-motor multitasking in everyday life, task performance is determined by the components of executive functions and physical fitness related to the specific task demands. Since multitasking in everyday life includes cognitive and motor tasks, it seems to be important to maintain both executive functions and physical fitness for independent living up to old age

Cognitive-motor multitasking in older adults: a randomized controlled study on the effects of individual differences on training success

Abstract Background Multitasking is an essential part of our everyday life, but performance declines typically in older age. Many studies have investigated the beneficial effects of cognitive, motor and combined cognitive-motor training on multitasking performance in older adults. Previous work, however, has not regarded interindividual differences in cognitive functioning and motor fitness that may affect training benefits. The current study aims to identify whether different training programs may have differential effects on multitasking performance depending on the initial level of cognitive functioning and motor fitness. Methods We conduct a 12-week single-blinded randomized controlled trial. A total of N = 150 healthy older adults are assigned to either a single cognitive, a single motor, or a simultaneous cognitive-motor training. Participants are trained twice per week for 45 min. A comprehensive test battery assesses cognitive functions, motor and cardiovascular fitness, and realistic multitasking during walking and driving in two virtual environments. We evaluate how multitasking performance is related not only to the training program, but also to participants’ initial levels of cognitive functioning and motor fitness. Discussion We expect that multitasking performance in participants with lower initial competence in either one or both domains (cognitive functioning, motor fitness) benefits more from single-task training (cognitive training and/or motor training). In contrast, multitasking performance in participants with higher competence in both domains should benefit more from multitask training (simultaneous cognitive-motor training). The results may help to identify whether tailored training is favorable over standardized one-size-fits all training approaches to improve multitasking in older adults. In addition, our findings will advance the understanding of factors that influence training effects on multitasking. Trial registration DRKS (German Clinical Trials Register), DRKS00022407. Registered 26/08/2020 - Retrospectively registered at https://www.drks.de/drks_web/setLocale_EN.d

Vhodnost výběru měřící techniky ke stanovení rychlosti hoření dle podmínek měření

Burning rate data are usually obtained in several ways. Small-scale ballistic evaluation motors, constant volume vessels, standard strand burners, and full-scale motors with good instrumentation are the most common methods used to measure the ballistic properties of solid propellants. The objective of this work is to describe the facilities developed by each measuring technique and validate the newly developed SV-2 for strand burning measurements at low and high pressures. Modifications were made to use the SV-2 closed bomb as a Crawford bomb. The sample holder and the closing tip were totally changed to enable burn rate measurements at the beginning of strand burn measuring. The burning rate of different commercial extruded double bases was measured using the modified SV-2 strand burning and compared with the burning rate resulting from subscale rocket motors. The results showed that the burning rates generated from both methods are comparable and close to each other. One firing from the subscale motor or strand burning is equal to one point on the P-u, curve. The effect of the initial grain temperature on the combustion process was investigated using the SV-2 closed vessel method compared to the subscale rocket motor method. Changes in the ignition process were reported through the variations in the durations for different ignition zones. The burning criteria were studied through the P-t curves and the actual burning time. The burning parameters (pressure exponent n and temperature coefficient a) were calculated. The results showed that raising the initial grain temperature increases the ignitability, burning rate, and operating pressure. The suitability of the burning rate measuring technique is discussed. The subscale rocket motor method can be considered the method that most closely simulates reality despite the fact that it requires more money and effort and is time consuming. Strand burning measurements are favorable when measuring the burning rates at lower operating pressures (2-10 MPa), while the method is not suitable for investigating the initial grain temperature effect on the combustion process. The SV-2 closed vessel can be considered a more convenient method for measuring the burning rate from an economical point of view.Cílem práce je popsat měření na zařízeních vyvinutých pro různé měřící techniky a ověřit techniku měření při vysokých a nízkých tlacích pomocí Stojanovy bomby SV-2 nově modifikované jako Crawfordova bomba. Rychlost hoření byla měřena pro různé komerční dvousložkové propelenty pomocí modifikované SV-2 a výsledky porovnány s měřením na raketových motorech. Výsledky ukazují, že měření rychlosti hoření pomocí těchto dvou technik dává srovnatelné výsledky. Byl sledován vliv počáteční teploty elementu na proces spalování měřením na raketových motorech a pomocí SV-2. Kritéria hoření byla studována pomocí P-t křivek a doby hoření, byly spočítány parametry hoření (tlakový exponent n a teplotní koeficient a). Výsledky ukazují, že zvýšení počáteční teploty elementu zvyšuje iniciovatelnost, rychlostí hoření a provozní tlak. V práci je diskutována vhodnost každé měřící techniky. Metoda raketového motoru nejlépe simuluje reálné podmínky hoření, je finančně a časově náročná, metoda Crawfordovy bomby je vhodná pro měření rychlosti hoření při nižších tlacích (2-10 MPa), není příliš vhodná pro měření vlivu počáteční teploty na proces hoření. Z ekonomického hlediska může být za vhodnou techniku měření rychlosti hoření považována Stojanova bomba

Energetické plastifikátory BuNENA-DNDA57 v nasakovaných TPH

Modification of cast double base propellants is somewhat of an art form. Obtaining a final propellant grain that has the right balance between energetic liquids and solid ingredients with the desired properties requires great effort. Four formulations of a modified cast double base propellant with different RDX contents have been prepared. A combination of BuNENA and DNDA57 energetic plasticizers has been used to overcome the problems that occur with a high nitroglycerin content. The effect of the RDX content on the burning behaviour, activation energies, and sensitivity to impact has been studied. Burning rate measurements have been performed using a closed bomb SV-2 to investigate the burning behaviour under a wide range of operating pressures. DTA and DSC thermal analysis were conducted to evaluate the thermal behaviour of the prepared modified double base propellants. The results showed that the formulation with only the combined plasticizer has the highest burning rate and activation energy and the lowest sensitivity to impact.K získání kvalitních nasakovaných TPH je nutné najít vhodný kompromis mezi energií TPH (danou obsahem energetických komponent) a dalšími vlastnosti TPH. Tato práce je zaměřena na charakterizaci TPH, v nichž je nitroglycerin nahrazen energetickými aditivy hexogenem a plastifikátory BuNENA a DNDA57. Sledován byl pak vliv těchto aditiv na následující vlastnosti: na rychlost hoření TPH v závislosti na okolním tlaku (měřeno v uzavřené bombě SV-2), na termické a stabilitní parametry (měřeno metodami DTA a DSC) a na citlivost TPH k nárazu. Nejvyšší rychlost hoření, nevyšší aktivační energii a zároveň nejnižší citlivost mají směsi jen s obsahem energetických plastifikátorů

Vliv plastifikátoru BuNENA na balistické a termické vlastnosti homogenních TPH

Preparation of cast double-propellant grains depends on the ability of nitrocellulose powder to swell and coalesce into a coherent mass when treated with a suitable solvent. The cast double-base process has been developed into a highly versatile technique for manufacturing solid rocket charges. Propellants manufactured by this process provide a wide range of energies and burning rates. Successful preparation of cast double-base propellant grains has been performed using compatible casting liquid with the casting powder. BuNENA was used as an energetic plasticizer for manufacturing of casting powder. Burning rate measurements have been performed using closed bomb SV-2 to investigate the burning behavior along a wide range of operating pressure. Plateau burning had been detected in pressure range (50-70)×105 Pa for the composition included BuNENA. DTA and TGA thermal analysis were conducted to evaluate the thermal behavior of the prepared cast double-base propellants. Results from DTA were used to calculate the apparent activation energy.Schopnost želatinátorů želatinovat nitrocelulózu je zásadním aspektem výroby homogenních TPH. Tyto želatinátory mají zásadní vliv na technologii výroby i na parametry výsledné TPH. Jako plastifikátor TPH byla zkoumána energetická látka BuNENA. U výsledných TPH s použitím tohoto plastifikátoru byla stanovena závislosti rychlosti hoření na vnějším tlaku pomocí měření v uzavřené bombě SV-2. Bylo nalezeno plato hoření v tlakovém rozmezí 50-70×105 Pa. U výsledných TPH byla rovněž stanovena termická stabilita pomocí metod DTA a TGA