Trends in adherence to the 24-h movement guidelines among US adolescents from 2011 to 2019: Evidence from repeated cross-sectional cycles of the Youth Risk Behavior Surveillance System.

BACKGROUND: Adherence to the 24-h movement guidelines is associated with various health benefits, but given the novelty of these integrative recommendations, little is known about year-to-year trends in guideline adherence in adolescents. This study investigated trends of adherence to the 24-h movement guidelines among US adolescents. METHODS: Data from 2011 to 2019 cycles of the Youth Risk Behavior Surveillance System were used, which included 62 589 US adolescents aged 14-17 years (female: unweighted sample size = 31 876, 51%; weighted% = 50.1%). Participants self-reported their demographic information (i.e., sex, age, race/ethnicity), physical activity, screen time and sleep duration. Meeting the 24-h movement guidelines was operationalized as simultaneously engaging in 60 min or more of moderate-to-vigorous physical activity, no more than 2 h of screen time, and 8-10 h of sleep per day. Trend analysis was used to examine the secular changes in adherence to the integrated guidelines from 2011 to 2019. RESULTS: Downward trends in adherence to the 24-h movement guidelines were observed among adolescents from 2011 (3.6%) to 2019 (2.6%). After stratification by sex, age, and race/ethnicity, similar downward trends in the guideline adherence were observed in females and Black/African American adolescents. The lowest prevalence of meeting the individual guidelines was for the PA guidelines (25.6%). Movement guideline adherence was consistently lowest among females, older adolescents, and those who identified as Black/African American. CONCLUSIONS: Adherence to the 24-h movement guidelines has declined among US adolescents over the past decade. Interventions should prioritize an integrative approach that could increase concurrent adherence to each of the 24-h movement guideline, particularly among female, older and minority adolescents.

The contribution and interplay of implicit and explicit processes on physical activity behavior: empirical testing of the physical activity adoption and maintenance (PAAM) model.

The adoption and maintenance of physical activity (PA) is an important health behavior. This paper presents the first comprehensive empirical test of the Physical Activity Adoption and Maintenance (PAAM) model, which proposes that a combination of explicit (e.g., intention) and implicit (e.g., habit,, affect) self-regulatory processes is involved in PA adoption and maintenance. Data were collected via online questionnaires in English, German, and Italian at two measurement points four weeks apart. The study included 422 participants (Mage= 25.3, SDage= 10.1; 74.2% women) from Germany, Switzerland, Italy, Canada, and the U.S. The study results largely supported the assumptions of the PAAM model, indicating that intentions and habits significantly mediate the effects of past PA on future PA. In addition, the effect of past PA on future PA was shown to be significant through a mediation chain involving affect and habit. Although the hypothesis that trait self-regulation moderates the intention-behavior relationship was not supported, a significant moderating effect of affect on the same relationship was observed. The results suggest that interventions targeting both explicit and implicit processes may be effective in promoting PA adoption and maintenance.

Independent and Joint Associations of Physical Activity and Sleep on Mental Health Among a Global Sample of 200,743 Adults.

BACKGROUND: Previous research has demonstrated that both sleep and physical activity (PA) are independently associated with various indicators of mental health among adults. However, their joint contribution to mental health has received limited attention. The present study used cross-sectional data from the Mental Health Million Project to examine the independent and joint effects of sleep and PA on mental health among a global sample of adults, and whether these effects differ among individuals receiving mental health treatment. METHOD: The sample included 200,743 participants (33.1% young adults, 45.6% middle-aged adults, 21.3% older adults; 57.6% females, 0.9% other) from 213 countries, territories, and archipelagos worldwide that completed a comprehensive 47-item assessment of mental health including both problems (i.e., ill-being) and assets (i.e., well-being): the Mental Health Quotient. Participants also reported their weekly frequency of PA and adequate sleep, and mental health treatment status. A series of generalized linear mixed models were computed. RESULTS: Independent dose-response associations were observed, whereby greater amounts of PA and adequate sleep were each associated with better mental health. In addition, a synergistic interaction was observed in which the positive correlation of PA with mental health was strengthened with greater frequency of adequate sleep. These benefits were less pronounced among adults receiving mental health treatment. CONCLUSION: While findings suggest sleep can help to offset the negative influence of a physically inactive lifestyle (and vice versa), our results point to a "more is better" approach for both behaviors when it comes to promoting mental health.

Comprehensive Associations between Acidosis and the Skeleton in Patients with Kidney Disease.

SIGNIFICANCE STATEMENT: Renal osteodystrophy (ROD) contributes substantially to morbidity in CKD, including increased fracture risk. Metabolic acidosis (MA) contributes to the development of ROD, but an up-to-date skeletal phenotype in CKD-associated acidosis has not been described. We comprehensively studied associations between acidosis and bone in patients with CKD using advanced methods to image the skeleton and analyze bone-tissue, along with biochemical testing. Cross-sectionally, acidosis was associated with higher markers of bone remodeling and female-specific impairments in cortical and trabecular bone quality. Prospectively, acidosis was associated with cortical expansion and trabecular microarchitectural deterioration. At the bone-tissue level, acidosis was associated with deficits in bone mineral content. Future work investigating acidosis correction on bone quality is warranted. BACKGROUND: Renal osteodystrophy is a state of impaired bone quality and strength. Metabolic acidosis (MA) is associated with alterations in bone quality including remodeling, microarchitecture, and mineralization. No studies in patients with CKD have provided a comprehensive multimodal skeletal phenotype of MA. We aim to describe the structure and makeup of bone in patients with MA in the setting of CKD using biochemistry, noninvasive imaging, and histomorphometry. METHODS: The retrospective cross-sectional analyses included 180 patients with CKD. MA was defined as bicarbonate ≤22 mEq/L. We evaluated circulating bone turnover markers and skeletal imaging with dual energy x-ray absorptiometry and high-resolution peripheral computed tomography. A subset of 54 participants had follow-up. We assessed associations between baseline and change in bicarbonate with change in bone outcomes. Histomorphometry, microCT, and quantitative backscatter electron microscopy assessed bone biopsy outcomes in 22 participants. RESULTS: The mean age was 68±10 years, 54% of participants were male, and 55% were White. At baseline, acidotic subjects had higher markers of bone turnover, lower areal bone mineral density at the radius by dual energy x-ray absorptiometry, and lower cortical and trabecular volumetric bone mineral density and impaired trabecular microarchitecture. Over time, acidosis was associated with opposing cortical and trabecular effects: cortical expansion but trabecular deterioration. Bone-tissue analyses showed reduced tissue mineral density with increased heterogeneity of calcium distribution in acidotic participants. CONCLUSIONS: MA is associated with multiple impairments in bone quality. Future work should examine whether correction of acidosis improves bone quality and strength in patients with CKD.

Relationship between Workload, Psychological State and Recovery in Female Soccer Athletes.

This study assessed the multifaceted relations between measures of workload, psychological state, and recovery throughout an entire soccer season in female collegiate soccer athletes (19.8±1.2 yrs, 132±12.3 lbs, 63±3.2 in). A prospective longitudinal study was utilized to measure workload (GPS training load, Rate of Perceived Exertion (RPE), psychological state (mental stress, mental fatigue, and mood), and recovery (sleep duration, sleep quality, and soreness), during 90 observations (59 training sessions and 21 games). Separate linear-mixed effect models were used to assess outcomes of RPE, soreness, and sleep duration. A linear mixed-effects model explained 59% of the variance in RPE following each session. Specifically, each standard deviation increase in GPS load and mental stress in the morning prior to training increased RPE by 1.46 (SE=0.08) and 0.29 (SE=0.07), respectively, following that day's training. Furthermore, a significant interaction was found between several predictor variables and chronological day in the season while predicting RPE. Specifically, for each standard deviation increase in GPS load, RPE went up by 0.0055 per day during the season suggesting that load had a higher impact on RPE as the season progressed. In contrast, the interaction of day by mental stress, sleep duration, and soreness continued to be stronger as the season progressed. Each linear mixed-effect model predicted a larger amount of variance when accounting for individual variations in the random effects.

The Sport Experience Measure for Children and Youth (SEM:CY): A Rasch Validation Study.

This study employed Rasch analyses to validate a novel measure of sport experience: the Sport Experience Measure: Children and Youth (SEM:CY). Analyses were applied to self-reported data of n = 503 young people (age 9-18 years, M = 12.91, 50% female) in Canada who were engaging in sport during the previous 12 months. The revised measure, consisting of 24 items on a 3-point response scale, demonstrated good fit statistics (e.g., item fit residual: M = -0.50, SD = 0.94 and person fit residual: M = -0.62, SD = 2.33), an ability to reliably discriminate between levels of sport experience, and an absence of differential item functioning for various groups (males and females, older and younger individuals, solo and team sports, and those playing at various competitive levels, including recreation). The SEM:CY is a succinct tool that can serve as a valuable means to gauge the quality of an individual's sport experience, which can facilitate positive youth development and sustain participation across the life span.

Associations between collagen X biomarker and linear growth velocity in a pediatric chronic kidney disease cohort.

BACKGROUND: Collagen X biomarker (CXM) is a novel biomarker of linear growth velocity. We investigated whether CXM correlated with measured growth velocity in children with impaired kidney function. METHODS: We used data from children aged 2 through 16 years old enrolled in the Chronic Kidney Disease in Children (CKiD) study. We assessed the association between CXM level and growth velocity based on height measurements obtained at study visits using linear regression models constructed separately by sex, with and without adjustment for CKD covariates. Linear mixed-effects models were used to capture the between-individual and within-individual CXM changes over time associated with concomitant changes in growth velocity from baseline through follow-up. RESULTS: A total of 967 serum samples from 209 participants were assayed for CXM. CXM correlated more strongly in females compared to male participants. After adjustment for growth velocity and CKD covariates, only proteinuria in male participants affected CXM levels. Finally, we quantified the between- and within-participant associations between CXM level and growth velocity. A between-participant increase of 24% and 15% in CXM level in females and males, respectively, correlated with a 1 cm/year higher growth velocity. Within an individual participant, on average, 28% and 13% increases in CXM values in females and males, respectively, correlated with a 1 cm/year change in measured growth. CONCLUSIONS: CXM measurement is potentially a valuable aid for monitoring growth in pediatric CKD. However, future research, including studies of CXM metabolism, is needed to clarify whether CXM can be a surrogate of growth in children with CKD. A higher resolution version of the Graphical abstract is available as Supplementary information.

The Home Advantage in the National Basketball Association Conference Finals and Finals Series From 1979 to 2019: A Mediation Analysis of Offensive and Defensive Skills.

This study examined the home advantage effect in decisive National Basketball Association Conference Finals and Finals series playoff games from 1979 to 2019 (the 3-point shot era). We also examined the potential contribution of various offensive- and defensive-based skills and whether these skills mediated the relationship between game status (decisive vs. nondecisive) and outcome (win vs. loss). Overall, we found evidence of a home court advantage with the home team winning 63% of the decisive playoff games and 66% of the nondecisive playoff games. After adjusting for multiple comparisons and regular season win percentage, the home team had significantly more defensive rebounds and steals in Game 5 when trailing 3-1 going into that game. Mediation analyses did not reveal any significant findings when examining the impact of decisive game status on performance through offensive and defensive skills, thus suggesting there are other explanations for the home advantage effect.

Application of the Multi-Process Action Control Model to Predict Physical Activity During Late Adolescence.

The aim of this study was to apply the Multi-Process Action Control model to examine how the additions of regulatory and reflexive processes predict physical activity (PA) behaviors among adolescents. Our sample included 1,176 Grade 11 students (Mage = 15.85 ± 0.38) recruited from a large school board in Southern Ontario. Participants completed a questionnaire including measures of self-reported PA and PA cognitions derived from the Multi-Process Action Control model. Results found the reflective process explaining 16.5% of the variance in PA, with the additions of regulatory and reflexive processes significantly improving the explained variance by 5.1% and 8.2%, respectively. Final models revealed coping planning (estimate = 45.10, p = .047), identity (estimate = 55.82, p < .001), and habit (estimate = 64.07, p < .001) as significant predictors of PA. Findings reinforce the need for integrative models to better understand PA, with coping planning, habit formation, and development of an active identity to be salient targets for intervention during adolescence.

Identifying patterns of movement behaviours in relation to depressive symptoms during adolescence: A latent profile analysis approach.

Movement behaviour guideline adherence has been associated with lower depressive symptoms during adolescence, yet no studies have used person-centered approaches to examine this relationship. The purpose of the present study was to identify whether unique adolescent movement behaviour profiles exist, evaluate predictors of profile membership, and determine whether profile membership was associated with differences in depressive symptoms cross sectionally and longitudinally. This study involved secondary analysis of the public-use data from Wave 1 and Wave 2 of the National Study of Adolescent Health. Adolescents (N = 6436; 48% male) in grades 7 to 12 (Mage = 16.03 ± 1.75) completed measures to assess moderate-to-vigorous physical activity (MVPA), recreational screen time (ST), and sleep - collectively known as movement behaviours - and depressive symptoms. Latent profile analysis identified four profiles that had similar sleep patterns and were thus characterized by different levels of MVPA and ST: high MVPA/low ST (29%), high MVPA/high ST (4%), low MVPA/low ST (53%), and low MVPA/high ST (14%). Several socio-demographic variables were found to influence profile membership. After adjusting for covariates, findings revealed depressive symptoms were lowest among the high MVPA/low ST profile and this trend was evident one year later. Engaging in high levels of either MVPA or ST alone did not provide additive benefits for depressive symptoms compared to those who engaged in low levels of both MVPA and ST. These findings suggest intervention efforts should take an integrative approach to improve mental health outcomes among adolescents by considering each of the movement behaviours concurrently.

Associations between 24-hour movement guideline adherence and mental health disorders among young people with active and inactive epilepsy.

OBJECTIVE: (1) Examine 24-hour movement guideline adherence among young people with active and inactive epilepsy compared to population norms. (2) Investigate associations between 24-hour movement guideline adherence and mental health disorders among these subpopulations. METHODS: Cross-sectional data from the 2016 to 2019 cycles of the National Survey of Children's Health were used. Parental/caregiver reports of movement behaviors (physical activity, screen time, sleep, and sport participation) were used to determine adherence to the 24-hour movement guidelines and associations with mental health disorders for young people with active (n = 663) and inactive epilepsy (n = 526) as well as population norms (n = 49,067) between 6 and 17 years old. Multivariate logistic regression analyses were conducted. RESULTS: Young people with active epilepsy were less likely to meet the 24-hour movement guidelines than population norms, largely driven by below average levels of physical activity guideline adherence. Sport participation was lower among both young people with active and inactive epilepsy; seizure severity and health-related limitations played an influential role. Beneficial associations were generally observed between 24-hour movement guideline adherence and mental health disorders, although for young people with active and inactive epilepsy, there was considerable variability among these relationships. CONCLUSIONS: Further dissemination of the International League Against Epilepsy's Task Force on Sports and Epilepsy report can help improve promotion of physical activity and sport participation among young people with active and inactive epilepsy. The relationship between 24-hour movement guideline adherence and mental health disorders is complex among young people with epilepsy and longitudinal research is needed to determine causal links.

Evaluating the impact of Archway: a personalized program for 1st year student success and mental health and wellbeing.

BACKGROUND: First-year students entering postsecondary education must navigate a new and complex academic and social environment. Research indicates that this transition and developmental period can be challenging and stressful - academically, emotionally and socially - and that mental health and wellbeing can be compromised. Additionally, mental health disorders can also compromise students' ability to successfully navigate this transition. In the COVID-19 pandemic, the incoming 2020 cohort of first-year students face heightened and new challenges. Most will have spent the conclusion of high school learning virtually, in quarantine, in an uncertain and difficult time, and are then experiencing their first year of university while living, learning and socializing off-campus, virtually and remotely. In response to COVID-19 and with an appreciation of the considerable stresses students face generally and particularly in 2020-21, and the potential effects on mental health and wellbeing, McMaster University, a mid-sized research intensive university with approximately 30,000 students, has developed an innovative program to support students, called Archway. This initiative has been developed to help to prevent and to intervene early to address common transitional issues students experience that can influence mental health and wellbeing, with the ultimate goals of increasing student connectedness, supports, and retention. METHODS: The current study will use a mixed-method design to evaluate Archway and gain a better understanding of the transition into first-year postsecondary for students who engage and participate in Archway at various levels. The study will not only help to determine the effect of this program for students during COVID-19, but it will help us to better understand the challenges of this transition more broadly. DISCUSSION: Findings have the potential to inform future efforts to support students and protect their mental health and wellbeing through the use of virtual and remote platforms and mechanisms that meet their increasingly diverse needs and circumstances.

Malaria and acute kidney injury.

Malaria is a parasitic infection transmitted by mosquitos, resulting in significant morbidity and mortality. It affects 212 million worldwide, causing death in up to 303,000 children annually. In the USA, up to 1700 people are affected yearly. Although the prevalence in developed countries is less than in developing countries, travelers from low transmission areas, and those from endemic areas who later return, are very susceptible to malaria and its complications. Severe malaria can cause significant multiorgan dysfunction including acute kidney injury (AKI). The pathogenesis is not clearly understood but proposed mechanisms include acute tubular necrosis (ATN) due to impediments in renal microcirculation, infection-triggered proinflammatory reactions within the kidney, and metabolic disturbances. Providers must consider malarial infection in cases of AKI in someone with a travel history, as early recognition and treatment are crucial to improving outcomes. This article will review malaria-induced AKI in order to provide a better understanding of this infection's effect on the kidneys.

Methods and design for the ADAPT study: Application of integrateD Approaches to understanding Physical activity during the Transition to emerging adulthood.

BACKGROUND: The overarching objective of the study is to obtain a comprehensive understanding of the salient factors predicting changes in physical activity (PA) during adolescents' transition into emerging adulthood. Using the Multi-Process Action Control model as our guiding framework, we will examine how implicit and explicit psychological processes along with regulatory practices impact PA change during this major life transition. Additionally, we will use a real-time data capture method called Ecological Momentary Assessment to further investigate how environmental and contextual factors, and momentary psychosocial influences effect PA patterns across this dynamic life stage. METHODS: The ADAPT study is a 4-year project comprised of two interrelated studies. Study I is a large prospective cohort study that will invite all grade 11 students across one large school board (a total of seven secondary schools) to participate by completing an online questionnaire. Using a cluster randomization approach, a subset of students from each school will be invited to participate in Study II, whereby participants will wear an accelerometer and complete Ecological Momentary Assessments 5 times a day over a 7-day study period. For both studies, following baseline assessments, there will be three annual follow-up assessments approximately 12 months apart. DISCUSSION: The current study represents one of the largest longitudinal cohort studies examining PA and its determinants and associated consequences among adolescents transitioning out of high school into emerging adulthood. Findings from this study will provide a much more in-depth understanding of how and why changes in PA behaviour occur across this first major life transition.

Effects of Mental Fatigue on Exercise Intentions and Behavior.

BACKGROUND: Exerting cognitive control results in mental fatigue, which is associated with impaired performance during physical endurance tasks. However, there has been little research on the effects of mental fatigue on people's perceptions or behaviors involving lifestyle or recreational exercise. PURPOSE: The purpose of this study was to examine the effect of mental fatigue on intended physical exertion and exercise performance reflective of current physical activity guidelines. METHODS: Using a counterbalanced design, participants completed two 50-min experimental manipulations (high vs. low cognitive control exertion) before exercising at a self-selected intensity for 30 min. At visit 1, participants performed a graded exercise task to gain familiarity with a range of exercise intensities and rating of perceived exertion (RPE) while exercising. At visits 2 and 3, participants rated their intended RPE for the exercise session, performed the experimental manipulations, re-rated their intended RPE, and then completed 30-min of exercise on a cycle ergometer. Total work performed while exercising was recorded for each session. RESULTS: Compared with the low cognitive control condition, the high cognitive control manipulation resulted in significantly greater mental fatigue (d = .73), significantly greater reductions in intended RPE (mean difference = -0.62), and significantly less total work (-12.7 kJ) performed during the exercise session. CONCLUSIONS: Mental fatigue alters the amount of physical effort people are willing to invest in an exercise workout and follow through with those intentions by doing less work. These are the first results showing people may deliberately adjust their physical effort to cope with mental fatigue.

Can behavioral strategies increase physical activity and influence depressive symptoms and quality of life among children with epilepsy? Results of a randomized controlled trial.

PURPOSE: This study examined whether increasing physical activity (PA) through 6 months of behavioral counseling positively influenced depressive symptoms and quality of life (QoL) over 12 months among children with epilepsy (CWE). METHODS: A longitudinal multisite randomized controlled trial (RCT) was conducted with 8-14-year-old children with active epilepsy. Participants wore a pedometer to track daily PA and completed 3 measures at 4 time points to examine depressive symptoms and QoL. Stratified by site and activity level, participants were randomized to an intervention or control group. The 6-month intervention included 11 behavioral counseling sessions targeting self-regulation of PA. To assess the associations among PA, depression scores, and QoL, primary analysis involved mixed-effects models. RESULTS: We recruited 122 CWE, of whom 115 were randomized (Mage = 11 ±â€¯2; 50% female) and included in the analysis. The intervention did not increase PA in the treatment compared with the control group. No differences were found between groups over time during the subsequent 6 months, where PA decreased among all participants. Results did not show differences between the groups and over time for measures of depressive symptoms and QoL. SIGNIFICANCE: The intervention did not improve or sustain PA levels over 12 months. Both groups demonstrated declines in PA over one year, but there were no changes in depression scores or QoL. As most participants were already nearly reaching the Canadian average of step counts of children their age, with a baseline daily step count of over 9000, there may be a challenge for further increasing PA over a longer period.

Cognitive control exertion leads to reductions in peak power output and [Formula: see text] as well as increased perceived exertion on a graded exercise test to exhaustion.

We investigated effects of a brief (10.5 min) cognitively demanding task on graded exercise test performance. Untrained, university students (N = 15) completed two graded exercise tests in counterbalanced, randomised order. One test was preceded by restful viewing of a documentary video (control); the other by a stop-signal task. Cardiorespiratory functions and perceived exertion were monitored during exercise. Peak power output (W) was lower following the stop-signal task (M = 240.03, SD = 53.37) compared to control (M = 246.03, SD = 52.60), P = 0.002, ηP2 = 0.493, as was [Formula: see text] (P = 0.042, Cohen's d = 0.55). Perceived exertion was significantly higher at 50% (d = 0.77) and 75% (d = 0.83) of iso-time following the cognitive task (Ps ≤ 0.01). Results are consistent with research showing negative carryover effects of cognitively demanding tasks on whole-body endurance performance. Results also support the psychobiological model of exercise as performance of the cognitive task did not affect perceived exertion when exercise task demands were lower, but lead to greater perceived exertion and earlier withdrawal of effort at higher levels of exercise task demand. Findings have implications for understanding psychological determinants of exercise performance and conditions that may lead to underestimation of [Formula: see text].

Effects of Mental Fatigue on Physical Endurance Performance and Muscle Activation Are Attenuated by Monetary Incentives.

Physical performance is impaired following cognitive control exertion. Incentives can ameliorate adverse carryover effects of cognitive control exertion but have not been investigated for physical endurance. This study examined the effect of monetary incentives on physical performance and muscle activation following exposure to a mentally fatiguing, cognitive control task. Participants (N = 82) performed two isometric endurance handgrip trials separated by a 12-min cognitive control manipulation using a 2 (high cognitive control [HCC]/low cognitive control [LCC]) × 2 (incentive/no incentive) design. Mental fatigue was significantly higher in the HCC conditions. Performance decreased in the HCC/no incentive condition but was unaffected in the HCC/incentive condition, which did not differ from the low cognitive control conditions. Electromyography data revealed increased muscle activation in the HCC/no incentive condition, which was also attenuated in the HCC/incentive condition. Findings show that incentives counteract the negative effects of HCC on physical endurance and alter central drive to motor units.

Effects of autonomous motivational priming on motivation and affective responses towards high-intensity interval training.

This study examined the effect of autonomous motivational priming on motivation, attitudes and intentions towards high-intensity interval training (HIT). Participants (N = 42) performed a graded exercise test to determine their peak aerobic power (WPEAK). At a subsequent testing session, participants were randomised to complete either an autonomous or neutral motivational priming task followed by a 10 × 1 HIT exercise protocol, alternating 1-min bouts of hard (70% WPEAK) and light (12.5% WPEAK) exercises for 20 min. Participants primed with autonomous motivation reported greater enjoyment, P = .009, ηp(2) = .16, and perceived competence, P = .005, ηp(2) = .18, post-exercise compared to those in the neutral priming condition. Participants in the autonomous motivational priming condition also reported more positive attitudes, P = .014, ηp(2) = .14, towards HIT; however, there was no difference between the conditions for task motivation during HIT or intentions, P = .53, ηp(2) = .01, to engage in HIT. These findings highlight autonomous motivational priming as a method of enhancing affective and motivational experiences regarding HIT.

Isometric exercise and cognitive function: an investigation of acute dose-response effects during submaximal fatiguing contractions.

The purpose of this study was to explore the dose-response relationship between exercise and cognitive performance using an acute bout of isometric exercise. University students (N = 55) were randomly assigned to control, 30%, 50% and 70% of maximum voluntary handgrip contraction groups. Participants performed a modified Stroop task before and after completion of an isometric handgrip endurance trial at their assigned exercise intensity. Ratings of perceived exertion (RPE) and forearm muscle activation (EMG) showed linear trends of progressively greater RPE and muscle activation at greater exercise intensity levels. Regression analysis showed significant (P < .05) linear degradations in frequency of errors on the Stroop task with increasing exercise intensity. We conclude that performing isometric exercise until exhaustion is associated with reduced cognitive performance and that higher intensity isometric exercise leads to greater performance impairments in a linear dose-response manner.