Aerobic Exercise, Cognitive Performance, and Brain Activity in Adolescents with Attention-Deficit/Hyperactivity Disorder.

INTRODUCTION: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder for which behavioral treatments such as exercise are recommended as part of a multidisciplinary treatment program. Exercise improves executive function in individuals with ADHD, but limited information exists regarding the mechanisms involved in the response. We examined task-evoked brain responses during exercise and seated rest in 38 adolescents ( n = 15 ADHD; age, 13.6 ± 1.9; male, 73.3%; n = 23 typically developing (TD; age, 13.3 ± 2.1; male, 56.5%)). METHODS: Participants completed a working memory and inhibitory task while cycling at a moderate intensity for 25 min (i.e., exercise condition) and while seated on the bike without pedaling (i.e., control condition). Conditions were randomized and counterbalanced. Functional near-infrared spectroscopy measured relative changes in oxygenated hemoglobin concentration in 16 brain regions of interest. Brain activity for each cognitive task and condition was examined using linear mixed-effects models with a false discovery rate (FDR) correction. RESULTS: The ADHD group had slower response speeds for all tasks and lower response accuracy in the working memory task during exercise compared with the TD group ( P < 0.05). For the inhibitory task, the ADHD group had lower brain activity in the inferior/superior parietal gyrus during exercise compared with the control condition, whereas the opposite was true for TD (FDR corrected , P < 0.05). For the working memory task, higher brain activity during exercise was observed, regardless of group, in the middle and inferior frontal gyrus and the temporoparietal junction (FDR corrected , P < 0.05). CONCLUSIONS: Dual-task performance is challenging for adolescents with ADHD, and exercise may modulate neuronal resources in regions such as the temporoparietal junction and frontal areas known to be hypoactive in this population. Future research should examine how these relationships change over time.

Reliability and validity of physical fitness tests in people with mental disorders: A systematic review and meta-analysis.

BACKGROUND: Several tests are available to assess the different components of physical fitness, including cardiorespiratory fitness, muscular strength, and flexibility. However, the reliability and validity of physical fitness tests in people with mental disorders has not been meta-analyzed. AIMS: To examine the reliability, concurrent, and convergent validity of physical fitness tests in people with mental disorders. METHODS: Studies evaluating the reliability, concurrent, and convergent validity of physical fitness tests in people with mental disorders were searched from major databases until January 20, 2020. Random-effects meta-analyses were performed pooling (1) reliability: test-retest correlations at two-time points, (2) convergent validity between submaximal tests and maximal protocols, or (3) concurrent validity between two submaximal tests. Associations are presented using r values and 95% confidence intervals. Methodological quality was assessed using the Quality Appraisal of Reliability Studies and the Critical Appraisal Tool. RESULTS: A total of 11 studies (N = 504; 34% females) were included. Reliability of the fitness tests, produced r values ranging from moderate (balance test-EUROFIT; [r = 0.75 (0.60-0.85); p = 0.0001]) to very strong (explosive leg power EUROFIT; [r = 0.96 (0.93-0.97); p = 0.0001]). Convergent validity between the 6-min walk test (6MWT) and submaximal cardiorespiratory tests was moderate (0.57 [0.26-0.77]; p = 0.0001). Concurrent validity between the 2-min walk test and 6MWT (r = 0.86 [0.39-0.97]; p = 0.0004) was strong. CONCLUSION: The present study demonstrates that physical fitness tests are reliable and valid in people with mental disorders.

Put on your (fNIRS) thinking cap: Frontopolar activation during augmented state creativity.

Thinking creatively requires the ability to consciously augment creative insight through processes such as analogical reasoning and relational cognition. Prior work has examined augmented states of creativity using a modified verb generation task which requires brief engagement in attempts to think creatively during MRI. In this study, we employed the verb generation task to examine augmented creative states and frontopolar cortex activation in a less-constrained setting using functional near infrared spectroscopy (fNIRS). Participants (n = 29) were presented with a noun and were required to think of an associated verb. In 50% of the trials, participants were instructed to 'think creatively' (cued condition) as opposed to stating the first or most prominent verb that came to mind (uncued condition). The task was administered in French to native speakers. Hemodynamic responses were recorded over the frontopolar cortex using fNIRS. The relatedness of the noun-verb pairs was calculated and other measures of creativity (the Alternate Uses Test, Compound Remote Associate Test and the Biographical Inventory of Creative Behaviors) were recorded. We showed that in the cued condition, semantic scores were higher (indicating more creative responses), positively associated with other measures of creativity, and changes in oxygenated hemoglobin were larger and more extensive in the left frontopolar cortex, than in the uncued condition. Our findings support the use of the verb generation task (administered in French) to augment creative states and provides further validation of the use of the task to capture creativity (i.e., processes involved in generating creative responses through distant associations). We highlight the use of fNIRS to measure associated regional changes in frontopolar cortex activity during augmented states of creativity.

The Utility of Functional Near-infrared Spectroscopy for Measuring Cortical Activity during Cycling Exercise.

PURPOSE: Real-time measurement of dynamic brain activity during exercise can help advance our understanding of the role of exercise upon brain health and function. In exercise science, functional near infrared spectroscopy (fNIRS) has primarily been used to measure the effects of exercise intensity on hemodynamic responses in the cerebral cortex. However, the utility of fNIRS to measure discreet hemodynamic responses underlying brain activation associated with motor and cognitive function during exercise has not been systematically examined. Here, we compared brain activation associated with a motor and cognitive task at rest and during cycling exercise at different intensities. METHODS: In separate sessions, 13 participants performed cycling exercise on an indoor trainer at a low, moderate and high intensity. We measured changes in oxygenated (HbO) and deoxygenated (HbR) hemoglobin from prefrontal, parietal, and motor regions of the cerebral cortex during a handgrip and working-memory task. RESULTS: Our findings show significant brain activation (a concurrent increase in HbO and decrease in HbR) in contralateral motor cortex during the handgrip task and left prefrontal cortex during the working-memory task at rest and during exercise at low, moderate and high (motor task HbO only) intensities (P < 0.05). Moreover, brain activation during the handgrip and working-memory tasks was not significantly different at rest and during exercise (P > 0.05). CONCLUSIONS: This study shows that fNIRS can robustly measure motor and cognitive task-evoked changes in brain activation during cycling exercise comparable to rest. An implication of these new findings is that fNIRS can be used to determine real-time changes in brain function during exercise in healthy and clinical populations.

Impact of Physical and Cognitive Exertion on Cognitive Control.

In a recent study, the differential effects of prolonged physiologically challenging exercise upon two executive processes (cognitive control and working memory) were investigated. However, the impact of exercise on the selective inhibition task employed was debatable and needed further analysis to dissociate the effects induced by exercise intensity from those induced by the time spent on task upon cognitive control outcomes. In this study, we propose a thorough analysis of these data, using a generalized mixed model on a trial-by-trial basis and a new measure of the strength of the automatic response based on reaction time distribution, to disentangle the effect of physical fatigue from cognitive fatigue. Despite the prolonged duration of exercise, no decline in cognitive performance was found in response to physical fatigue. The only change observed during 60-min exercise was an acceleration of the correct trials and an increase of errors for incompatible trials. This pattern, shown during low and physiologically challenging exercise, supports the occurrence of cognitive fatigue induced by the repetition of the cognitive tasks over time.

The long and winding road: Effects of exercise intensity and type upon sustained attention.

Aerobic exercise enhances the ability to sustain attention (peaking at moderate intensities) by stimulating noradrenergic activity, which affects the fronto-parietal attention network. Prior exercise studies examining attention have focused on the influence of exercise intensity, yet few studies have examined the influence of the type of exercise protocol administered. Here, we propose that sustained attention is greater during (a) moderate compared to low intensity exercise, and (b) moderate intensity exercise administered at a varied-load compared to a constant-load but the same overall intensity. To test this hypothesis, we recorded attentional focus in twelve male cyclists during a sustained attention to response task (SART) in four conditions; at rest, and during exercise at a low constant-, moderate constant- and moderate varied-load intensity. The change in α-amylase (indicative of the noradrenergic response) from saliva samples and activation of the right prefrontal and parietal cortices using near-infrared spectroscopy were recorded. The findings revealed that moderate intensity exercise at a constant-load leads to faster responses and less accuracy in the SART than rest and low intensity exercise. Moderate intensity exercise at a variable-load leads to even faster responses but with no loss of accuracy in the SART. This pattern of results is explained by a larger increase in salivary α-amylase during moderate (constant and varied) intensity cycling and higher activation in the dorso-lateral prefrontal cortex during the varied, but not the constant-load condition. In conclusion, we show that, in addition to exercise intensity, the type of exercise also has important implications upon attentional focus. While moderate intensity exercise generally enhances attentional focus, monotonous exercise at a constant-load may mask such benefits.

Prefrontal oxygenation and the acoustic startle eyeblink response during exercise: A test of the dual-mode model.

The interplay between the prefrontal cortex and amygdala is proposed to explain the regulation of affective responses (pleasure/displeasure) during exercise as outlined in the dual-mode model. However, due to methodological limitations the dual-mode model has not been fully tested. In this study, prefrontal oxygenation (using near-infrared spectroscopy) and amygdala activity (reflected by eyeblink amplitude using acoustic startle methodology) were recorded during exercise standardized to metabolic processes: 80% of ventilatory threshold (below VT), at the VT, and at the respiratory compensation point (RCP). Self-reported tolerance of the intensity of exercise was assessed prior to, and affective responses recorded during exercise. The results revealed that, as the intensity of exercise became more challenging (from below VT to RCP), prefrontal oxygenation was larger and eyeblink amplitude and affective responses were reduced. Below VT and at VT, larger prefrontal oxygenation was associated with larger eyeblink amplitude. At the RCP, prefrontal oxygenation was greater in the left than right hemisphere, and eyeblink amplitude explained significant variance in affective responses (with prefrontal oxygenation) and self-reported tolerance. These findings highlight the role of the prefrontal cortex and potentially the amygdala in the regulation of affective (particularly negative) responses during exercise at physiologically challenging intensities (above VT). In addition, a psychophysiological basis of self-reported tolerance is indicated. This study provides some support of the dual-mode model and insight into the neural basis of affective responses during exercise.

The differential effects of prolonged exercise upon executive function and cerebral oxygenation.

The acute-exercise effects upon cognitive functions are varied and dependent upon exercise duration and intensity, and the type of cognitive tasks assessed. The hypofrontality hypothesis assumes that prolonged exercise, at physiologically challenging intensities, is detrimental to executive functions due to cerebral perturbations (indicated by reduced prefrontal activity). The present study aimed to test this hypothesis by measuring oxygenation in prefrontal and motor regions using near-infrared spectroscopy during two executive tasks (flanker task and 2-back task) performed while cycling for 60min at a very low intensity and an intensity above the ventilatory threshold. Findings revealed that, compared to very low intensity, physiologically challenging exercise (i) shortened reaction time in the flanker task, (ii) impaired performance in the 2-back task, and (iii) initially increased oxygenation in prefrontal, but not motor regions, which then became stable in both regions over time. Therefore, during prolonged exercise, not only is the intensity of exercise assessed important, but also the nature of the cognitive processes involved in the task. In contrast to the hypofrontality hypothesis, no inverse pattern of oxygenation between prefrontal and motor regions was observed, and prefrontal oxygenation was maintained over time. The present results go against the hypofrontality hypothesis.

A comparison of head motion and prefrontal haemodynamics during upright and recumbent cycling exercise.

The aim of this observational study was to compare head motion and prefrontal haemodynamics during exercise using three commercial cycling ergometers. Participants (n = 12) completed an incremental exercise test to exhaustion during upright, recumbent and semi-recumbent cycling. Head motion (using accelerometry), physiological data (oxygen uptake, end-tidal carbon dioxide [PET CO2 ] and heart rate) and changes in prefrontal haemodynamics (oxygenation, deoxygenation and blood volume using near infrared spectroscopy [NIRS]) were recorded. Despite no difference in oxygen uptake and heart rate, head motion was higher and PET CO2 was lower during upright cycling at maximal exercise (P<0·05). Analyses of covariance (covariates: head motion P>0·05; PET CO2 , P<0·01) revealed that prefrontal oxygenation was higher during semi-recumbent than recumbent cycling and deoxygenation and blood volume were higher during upright than recumbent and semi-recumbent cycling (respectively; P<0·05). This work highlights the robustness of the utility of NIRS to head motion and describes the potential postural effects upon the prefrontal haemodynamic response during upright and recumbent cycling exercise.

Patterning of physiological and affective responses in older active adults during a maximal graded exercise test and self-selected exercise.

PURPOSE: The American College of Sports Medicine has highlighted the importance of considering the physiological and affective responses to exercise when setting exercise intensity. Here, we examined the relationship between exercise intensity and physiological and affective responses in active older adults. METHOD: Eighteen participants (60-74 years; 64.4 ± 3.9; 8 women) completed a maximal graded exercise test (GXT) on a treadmill. Since time to exhaustion in the GXT differed between participants, heart rate (HR), oxygen consumption (VO2), affective valence (affect) and rating of perceived exertion (RPE) were expressed relative to the individually determined ventilatory threshold (%atVT). RESULT: During the GXT, VO2, HR and RPE increased linearly (all P < 0.01). Affect declined initially (but remained positive) (P = 0.03), stabilised around VT (still positive) (P > 0.05) and became negative towards the end of the test (P < 0.01). In a subsequent session, participants completed a 20-min bout of self-selected exercise (at a preferred intensity). Initially, participants chose to exercise below VT (88.2 ± 17.4 %VO2atVT); however, the intensity was adjusted to work at, or above VT (107.7 ± 19.9 %VO2atVT) after 10 min (P < 0.001), whilst affect remained positive. CONCLUSION: Together, these findings indicate that exercise around VT, whether administered during an exercise test, or self-selected by the participant, is likely to result in positive affective responses in older adults.

Prefrontal cortex haemodynamics and affective responses during exercise: a multi-channel near infrared spectroscopy study.

The dose-response effects of the intensity of exercise upon the potential regulation (through top-down processes) of affective (pleasure-displeasure) responses in the prefrontal cortex during an incremental exercise protocol have not been explored. This study examined the functional capacity of the prefrontal cortex (reflected by haemodynamics using near infrared spectroscopy) and affective responses during exercise at different intensities. Participants completed an incremental cycling exercise test to exhaustion. Changes (Δ) in oxygenation (O2Hb), deoxygenation (HHb), blood volume (tHb) and haemoglobin difference (HbDiff) were measured from bilateral dorsal and ventral prefrontal areas. Affective responses were measured every minute during exercise. Data were extracted at intensities standardised to: below ventilatory threshold, at ventilatory threshold, respiratory compensation point and the end of exercise. During exercise at intensities from ventilatory threshold to respiratory compensation point, ΔO2Hb, ΔHbDiff and ΔtHb were greater in mostly ventral than dorsal regions. From the respiratory compensation point to the end of exercise, ΔO2Hb remained stable and ΔHbDiff declined in dorsal regions. As the intensity increased above the ventilatory threshold, inverse associations between affective responses and oxygenation in (a) all regions of the left hemisphere and (b) lateral (dorsal and ventral) regions followed by the midline (ventral) region in the right hemisphere were observed. Differential activation patterns occur within the prefrontal cortex and are associated with affective responses during cycling exercise.