Short Bouts Research Articles

Magnitude, timing and duration of mood state and cognitive effects of acute moderate exercise in major depressive disorder

BackgroundAcute exercise generally improves mood state and cognitive functioning in healthy adults. However, the impact of acute exercise on primary symptoms in adults with major depressive disorder (MDD) is poorly understood. The present randomized cross-over study evaluated the magnitude, timing, and duration of the psychological effects of 30 min of moderate-intensity cycling exercise compared to quiet rest in 30 adults (21 female) with MDD. MethodsDepressed mood state (Profile of Mood States Short Form-Depression; POMS-D), state anhedonia (anhedonia Visual Analog Scale [VAS], and Dimensional Anhedonia Rating Scale [DARS]), and cognition (inhibition via Stroop and working memory via the 2-back task) were assessed pre, mid, post, 25-, 50- and 75-min after each session. ResultsGeneralized estimating equations demonstrated significant session by time interactions for POMS-D and VAS indicating small-to-large improvements in mood state and anhedonia up to 75 min post-exercise (p < 0.05; Cohen’s d ranges: POMS [-0.69, -0.95]; DARS, [-0.02, 0.16]; VAS [0.33, 0.83]) with greater immediate effects that lessened somewhat across time. For cognition, Stroop reaction time improved during exercise, but was worse at 25- and 50-min post-exercise compared to quiet rest (p < 0.05); no differences were found for 2-back reaction time. LimitationsThe small sample and continued psychological effects at 75 min indicate a potentially longer-lasting response than was measured herein. ConclusionPerforming short bouts of moderate intensity exercise appears to be effective for management of key symptoms (anhedonia, depressed mood state) in adults with MDD. The time immediately post-exercise may be ideal for performing emotionally challenging tasks and/or tasks where a low symptom severity would be helpful (e.g., psychotherapy).

Comparison of the Impact of Conventional and Web-Based Pulmonary Rehabilitation on Physical Activity in Patients With Chronic Obstructive Pulmonary Disease: Exploratory Feasibility Study.

BackgroundPulmonary Rehabilitation (PR) increases exercise capacity, with less clear evidence regarding physical activity (PA). The World Health Organization recommends at least 150-300 minutes of moderate-intensity or 75-150 minutes of vigorous-intensity aerobic PA per week to reduce the risks of chronic disease.ObjectiveThe objective of this study was to assess the effectiveness of conventional PR versus web-based PR with respect to changes in PA.MethodsPatients with COPD were randomized to either conventional PR classes (n=51) or a web-based PR program (n=52) for 7 weeks in a feasibility study. Accelerometers (Sensewear) were worn before and after the intervention, and PA was measured as steps per day and mean bouts of moderate activity for ≥2, ≥5, ≥10, and ≥20 minutes. Measures were derived for patients with ≥8 hours of data per day for ≥4 days, using the R package for statistical analysis. Variables were explored to examine their relationships with bouts of activity.ResultsBaseline characteristics did not differ significantly between groups. Complete PA data were available for the groups receiving web-based (n=20) and conventional (n=34) PR interventions. The web-based PR group demonstrated a nonsignificant increase in the number of steps per day, which mainly comprised short bouts of moderate to vigorous intensity PA when compared to the conventional PR group (P=.20). The conventional PR group demonstrated increased 20-minute bouts of PA by 49.1%, although this was not significant (P=.07). At baseline, age (r=–0.21, P=.04), BMI (r=–0.311, P=.004), and FEV1 (forced expiratory volume in 1 second; % predicted; r=–0.248, P=.048) were significantly correlated with 10-minute bouts of PA; however, this was not observed post intervention.ConclusionsThe analysis revealed a nonsignificant difference in the pattern of PA between groups receiving conventional vs web-based PR—the former being associated with an increase in 20-minute bouts, while the latter having demonstrated an increase in the number of steps per day. There appears to be a differing response emerging between the two interventions.Trial RegistrationInternational Clinical Trials Registry ISRCTN03142263; https://tinyurl.com/y4dmfyrb

Attenuated Metabolic and Cardiorespiratory Responses to Isoenergetic High-Intensity Interval Exercise of Short Versus Long Bouts.

To compare the metabolic, cardiorespiratory and perceptual responses to three isoenergetic high-intensity interval exercise (HIIE) protocols of different bout duration and an isoenergetic continuous exercise protocol. Eleven healthy males (age, 28 ± 6 yr) performed four 20-min cycling trials of equal mean power output 1 wk apart. Participants cycled either continuously (CON) or intermittently with 10 s (HIIE10), 30 s (HIIE30), or 60 s (HIIE60) bouts at intensities corresponding to 49% (CON) or 100% of power at peak oxygen uptake (V̇O2peak). Recovery intervals during the HIIE trials were 15, 45, and 90 s, respectively. Average V̇O2 was similar in the HIIE trials (2.29 ± 0.42, 2.20 ± 0.43, and 2.12 ± 0.45 L·min-1, for HIIE10, HIIE30, and HIIE60, respectively), whereas in CON (2.02 ± 0.38 L·min-1), it was lower than HIIE10 (P = 0.002) and HIIE30 (P = 0.043). Average pulmonary ventilation (VE) was higher in HIIE60 compared with HIIE10, HIIE30, and CON (75.8 ± 21.8 L·min-1 vs 64.1 ± 14.5 L·min-1, 64.1 ± 16.2 L·min-1, and 54.0 ± 12.5 L·min-1, respectively, P < 0.001). The peak values and oscillations of V̇O2 and VE in HIIE60 were higher compared with all other trials (P < 0.001). Blood lactate concentration was higher in HIIE60 compared with HIIE10, HIIE30, and CON from the fifth minute onward, reaching 12.5 ± 3.5, 7.2 ± 2.1, 7.9 ± 2.9, and 4.9 ± 1.6 mmol·L-1, respectively, at the end of exercise (P < 0.001). RPE was higher and affective responses were lower in HIIE60 compared with all other trials toward the end of exercise (P < 0.001). These findings highlight the importance of bout duration in HIIE, since shorter bouts resulted in attenuated metabolic and cardiorespiratory responses, lower RPE and feelings of displeasure compared with a longer bout, despite equal total work, duration, and work-to-recovery ratio. These results may have implications for the prescription of HIIE in various populations.

Properties and hemispheric differences of theta oscillations in the human hippocampus.

The left and right primate hippocampi (LH and RH) are thought to support distinct functions, but little is known about differences between the hemispheres at the neuronal level. We recorded single-neuron and local field potentials from the human hippocampus in epilepsy patients implanted with depth electrodes. We detected theta-frequency bouts of oscillatory activity while patients performed a visual recognition memory task. Theta appeared in bouts of 3.16 cycles, with sawtooth-shaped oscillations that had a prolonged downswing period. Outside the seizure onset zone, the average frequency of theta bouts was higher in the RH compared to the LH (6.0 vs. 5.3 Hz). LH theta bouts had lower amplitudes and a higher prevalence compared to the RH (26% vs. 21% of total time). Additionally, the RH contained a population of thin spiking visually tuned neurons that were not present in the LH. These data show that human theta appears in short oscillatory bouts whose properties vary between hemispheres, thereby revealing neurophysiological properties of the hippocampus that differ between the hemispheres.

Is Complexity of Daily Activity Associated with Physical Function and Life-Space Mobility among Older Adults?

ABSTRACTPurposeInformation about mobility and physical function may be encoded in the complexity of daily activity pattern. Therefore, daily activity pattern complexity metrics could provide novel insight into the relationship between daily activity behavior and health. The purpose of the present study was to examine the association between the complexity of daily activity behavior and the mobility and physical function among community-dwelling older adults 75, 80, and 85 yr of age.MethodsA total of 309 participants wore accelerometers concurrently on the thigh and the trunk for at least three consecutive days. Five activity states (lying, sitting, standing, walking, or activity other than walking) were defined in three different temporal grains (5 s, 1 min, and 5 min), and Lempel–Ziv complexity was evaluated. We assessed complexity of daily activity behavior using the life-space mobility and physical function with distance in preferred pace 6-min walk and the Short Physical Performance Battery.ResultsWeak positive associations were observed between the complexity of daily activity and the mobility and physical function at the finest temporal grains in both sexes (Spearman rho = 0.19 to 0.27, P < 0.05). No significant associations were observed in the coarsest temporal grain in either sex.ConclusionsLempel–Ziv estimates of daily activity complexity with a fine temporal grain seem to be associated with community-dwelling older adults’ physical function. The coarsest 5-min temporal grain may have smoothed out physiologically meaningful short activity bouts. Because complexity encodes information related to timing, intensity, and patterning of behavior, complexity of activity could be an informative indicator of future physical function and mobility.

Patterns of Accelerometer-Measured Physical Activity and Health Outcomes in Adults: A Systematic Review.

The aim of this study was to systematically review the literature on accelerometer-measured physical activity and health outcomes in adults. Eight electronic databases were searched for relevant articles published up to March 2021. Only population-based studies of adults (age ≥18 yr) that directly compared two or more categories of physical activity (i.e., bout duration, intensity, and daily/weekly frequency) with a health outcome (e.g., mortality, cardiometabolic, healthy aging, depression, sleep, and brain structure) were included. Of the 15,923 publications retrieved, 52 articles were included. Twenty-eight studies directly compared the associations between physical activity accumulated in different bout durations, 31 studies directly compared the associations between physical activity accumulated in different intensities, and 9 studies directly compared the associations between the effects of varying daily and weekly frequencies of physical activity, with health outcomes. Most showed no differences in relationships with health outcomes when physical activity was accumulated in short (<10-min) or long (≥10-min) bouts. Overall, there were no differences in the relationships with most health outcomes when different intensities and daily/weekly frequencies were compared. However, in most studies, researchers did not adjust their analyses for total volume of physical activity. Moreover, variations in researcher-driven decisions about data collection and processing methods made it difficult to compare study findings. These findings suggest that physical activity accumulated in many patterns of bout duration, intensity, or daily/weekly frequency is associated with a range of beneficial health outcomes in adults. Lack of adjustment for total volume of physical activity in most studies and inconsistent methods for defining components of physical activity prevent firm conclusions about which specific patterns of bout duration, intensity, and daily/weekly frequency are most important for health benefits.

Stressed in afterthought: Neuroendocrine effects of social self-threat during physical effort are counteracted by performance feedback after stress exposure

Social self-threat during physical stress, such as exposure to the cold pressor test and isometric handgrip test, has been shown to induce activation of the HPA axis, in addition to autonomic responses. However, previous research has suggested that dysfunctional post-event processing may play a major role in neuroendocrine reactivity at initial as well as subsequent social stress exposure. In the present study, we investigated how the interplay of context (i.e. performance feedback) with state (i.e., self-esteem) as well as trait-like factors (i.e., ruminative tendencies) affects stress responses to repeated, short bouts of physical activity. On two sessions, 1 week apart, 53 participants (27 women) performed an isometric handgrip task for 3 min, during which they were exposed to social-evaluative threat. In addition, participants received fake feedback on their performance immediately after the task, labeling it as either ‘above’ (positive) or ‘below average’ (negative). In addition to neuroendocrine (cortisol), cardiovascular (heart rate, blood pressure) and subjective stress reactivity, performance-related and social dimensions of state self-esteem were assessed before and after stress induction. Substantial increases in cardiovascular parameters were found on both days, regardless of feedback condition. However, positive feedback led to significantly diminished neuroendocrine responses on day 1, whereas baseline cortisol on session 2 was significantly higher in the negative feedback group. Conversely, social self-esteem decreased after stress induction on both days only for participants who had received negative feedback. Changes in self-esteem reported on day 1 were associated with increased baseline cortisol at the second session, while interindividual differences in self-reported (trait) rumination were associated with cortisol reactivity at session 1. Taken together, the results suggest that effects of social evaluation during short periods of physical stress rely on post-event processing and might be counteracted by positive appraisal directly after stress exposure. Post-hoc framing (in terms of success vs. failure) may predict subsequent stress-related hormonal effects better than task demands per se, which should be considered as a potential moderator in future acute stress research, but might also be relevant to many practical applications in fields ranging from sports/performance to health psychology.

Acute effects of aerobic exercise on conflict suppression, response inhibition, and processing efficiency underlying inhibitory control processes: An ERP and SFT study.

Aerobic exercise has been identified as an effective strategy for transiently enhancing inhibitory control, an ability to suppress irrelevant distractors while focusing on relevant information in facilitating the implementation of goal-directed behavior. The purpose of this study was to employ a go/no-go version of the redundant-target task and event-related potential to further determine whether inhibitory control at the perceptual and response levels as well as their underlying processing capacity and neuroelectric alterations are differentially affected by a single bout of aerobic exercise. Twenty-seven young adults completed the redundant-target task while electroencephalogram was recorded before and after one 20-min bout of moderate-intensity aerobic exercise and a sitting control condition on separate days in counterbalanced order. Although behavioral outcomes of mean-level performance did not differ between intervention conditions, time-related decreases in processing capacity for the faster responses were only observed following rest. Aerobic exercise resulted in maintained P3b amplitude from pretest to posttest for all trial types while decreased P3b amplitude from pretest to posttest during single-target and redundant-target trials was observed following rest. Further, the time-related changes in P3b amplitude were positively correlated with improvements in task performance following exercise. These findings suggest that a short bout of aerobic exercise selectively counteracts the time-related decrements in processing capacity as well as neuroelectric processing of attention and conflict suppression that contribute to behavioral outcomes of inhibitory control.

Two hours of heat stress induces MAP-kinase signaling and autophagasome accumulation in C2C12 myotubes.

Short bouts of heat can induce a hormetic stress response, whereas prolonged or excessive exposure can elicit detrimental effects. We previously demonstrated an increase in autophagic signaling in C2C12 myotubes in response to 1 h of heat at 40 °C. In opposition, longer durations of heat exposure (e.g., 12 and 24 h) lead to an accumulation of autophagasomes and elevations in markers of cellular inflammation, oxidative stress, and apoptosis. Whether a longer, yet moderate, duration of 2 h of heat further enhances autophagic flux and attenuates stress and inflammatory signaling, or transitions the cell toward a dysregulation of autophagy is unclear. In this study, C2C12 myotubes were maintained at 37 °C or exposed to 40 °C (HT) for 2 h, and harvested immediately or following 2, 8, or 24 h of recovery. Two hours of HT immediately increased pAMPK (T172; p = 0.001), and subsequently increased pULK1 (S555) at 2 h of recovery (p = 0.028). LC3 II was increased at 8 h (p = 0.043) and 24 h (p = 0.015) of recovery, whereas p62 was elevated at 2 h (p = 0.002) and 8 h (p < 0.001) of recovery, but returned to baseline by 24 h. In Bafilomycin A1 treated cells, p62 was further increased immediately following HT (p = 0.041). There was also a significant elevation in p-p38 (Thr180/Try182), pJNK (Thr183/Tyr185), and pNFκB (Ser536). These findings suggest that as short as 2 h of heat exposure contributes to cell stress and accumulation of autophagasomes in skeletal muscle.

Normalization of global longitudinal strain after 20 squats in elite athletes

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction: Transthoracic echocardiography (TTE) is often the first diagnostic imaging modality of choice in athlete care to differentiate between physiological adaptation to sports and pathology. Left ventricular (LV) global longitudinal strain (GLS) has been suggested as a tool to detect early signs of myocardial diseases in athletes. However, low rates of myocardial deformation can also be associated with cardiac adaptation to sports. We hypothesized that observing decreased cardiac deformation in elite athletes may be a sign of an outspoken relaxed cardiac state, rather than pathology. Therefore, we investigated whether a short exercise bout can normalize strain values in elite athletes with abnormal resting GLS. Methods We prospectively enrolled elite athletes who participated in the ELITE (Evaluation of Lifetime Participation in Intensive Top-level Sports and Exercise) cohort. In short, ELITE is a prospective athlete cohort, which collects medical history, ECG, TTE and cardiac magnetic resonance (CMR) data in elite athletes (Olympic/Paralympic level or comparable). For this analysis, we analysed TTEs of asymptomatic athletes without cardiovascular disease and with a structurally normal heart on CMR. TTE (Vivid, GE) was performed in each athlete according to guidelines at rest. After a short exercise bout, consisting of 20 squats, additional GLS, LV ejection fraction (EF), and LV stroke volume (SV) measurements were assessed when heart-rate (HR) was comparable to HR during pre-exercise measurements. TTE data was assessed using EchoPAC (GE). GLS delta (pre- to post-exercise) for each athlete was calculated were plotted, using R. GLS ≥ -16% was considered decreased and -16% ≥ GLS &amp;gt; -18% borderline. Results Our population comprised 73 athletes (26% women), mean age (±SD) of 25.6 ± 6.5 years, BSA of 2 ± 0.2m2, and athletic disciplines road cycling (n = 28), soccer (n = 12), hockey (n = 8), swimming (n = 5), tennis (n = 5) and 8 miscellaneous sports (n = 15). Mean pre- and post-exercise GLS were -18.2 ± 2.1% vs -20.5 ± 2.0% (P &amp;lt; 0.001; Figure 1), EF 57 ± 4% vs 59 ± 6% (P = 0.006; Figure 1), SV 89 ± 20ml vs 99 ± 24ml (P = 0.008), and HR 56 ± 12bpm vs 56 ± 13bpm (P = 0.875). We observed an increase of myocardial deformation after a short bout of exercise: mean GLS delta of -2.3 ± 1.9%. Finally, we found a decreased strain in 14 athletes (19%), in which pre- and post-exercise GLS were -15.1 ± 0.8% and -18.6 ± 2.3%, P= &amp;lt;0.001, Figure 1). Only 1 athlete (1%, no other signs of cardiac pathology: MRI, biomarkers, complaints) had post-exercise decreased GLS. We found 9 athletes with a deteriorated cardiac deformation (delta GLS ≤ 0%), pre- and post-exercise GLS were -20.4 ± 1.4% and -19.9 ± 1.5% (maximal GLS post-exercise was -17.7%, Figure 1). Conclusion GLS normalizes in 99% of healthy (elite) athletes. In athletes with decreased GLS at rest, performing a short exercise bout is a pragmatic method to separate decreased GLS due to pathology from sport adaptation Abstract figure 1

Automated Grooming Detection of Mouse by Three-Dimensional Convolutional Neural Network.

Grooming is a common behavior for animals to care for their fur, maintain hygiene, and regulate body temperature. Since various factors, including stressors and genetic mutations, affect grooming quantitatively and qualitatively, the assessment of grooming is important to understand the status of experimental animals. However, current grooming detection methods are time-consuming, laborious, and require specialized equipment. In addition, they generally cannot discriminate grooming microstructures such as face washing and body licking. In this study, we aimed to develop an automated grooming detection method that can distinguish facial grooming from body grooming by image analysis using artificial intelligence. Mouse behavior was recorded using a standard hand camera. We carefully observed videos and labeled each time point as facial grooming, body grooming, and not grooming. We constructed a three-dimensional convolutional neural network (3D-CNN) and trained it using the labeled images. Since the output of the trained 3D-CNN included unlikely short grooming bouts and interruptions, we set posterior filters to remove them. The performance of the trained 3D-CNN and filters was evaluated using a first-look dataset that was not used for training. The sensitivity of facial and body grooming detection reached 81.3% and 91.9%, respectively. The positive predictive rates of facial and body grooming detection were 83.5% and 88.5%, respectively. The number of grooming bouts predicted by our method was highly correlated with human observations (face: r = 0.93, body: r = 0.98). These results highlight that our method has sufficient ability to distinguish facial grooming and body grooming in mice.

Acute effects of low-volume intermittent versus higher-volume continuous exercise on arterial stiffness in healthy young men

To compare the acute effects of low-volume intermittent and higher-volume continuous exercise on arterial stiffness, 20 healthy men (22.4 ± 0.4 years) were randomized to non-exercise control (CON), high-volume Continuous Exercise (CE), lower-volume Intermittent exercise of Long bouts with Long interval (ILL), of Long bouts with Short interval (ILS), and of Short bouts with Short interval trial (ISS). Exercise intensity was 35% heart rate reserve. Arterial stiffness in Cardio-ankle vascular index (CAVI) was measured at baseline (BL), immediately (0 min) and 40 min after exercise. CAVI changes from BL in the same trial (⊿CAVI) were used for analysis. There was no significant ⊿CAVI change in CON. ⊿CAVI decreased significantly at 0 min in all exercise trials, and reverted to baseline at 40 min only in CE and ILL. At 40 min, ⊿CAVI in ILS and ISS remained significantly lower than that of CON and CE. When ILS and ISS were compared with CON at 40 min, only ⊿CAVI in ISS remained significantly lower than that of CON. Despite low volume, the effect of intermittent exercise on arterial stiffness could be either equal or superior to that of higher-volume continuous exercise.

No Change in Inhibitory Control or P3 Following Different High-Intensity Interval Exercise Modalities.

Acute aerobic high-intensity interval exercise (HIIE) has demonstrated positive effects on inhibitory control and P3 event-related potential (ERP) in young adults. However, the evidence is not well established regarding the effects of different HIIE modalities that incorporate aerobic-resistance training on these cognitive and neurocognitive outcomes. The purpose of this investigation was to examine the transient effects of HIIE-aerobic and HIIE-aerobic/resistance on P3 and Flanker task performance. Participants (n = 24; 18–25 years old) completed the Flanker task at two time points (30 min and 85 min) following 9 min of HIIE-aerobic (intermittent bouts of walking and running at 90% of maximal heart rate), HIIE-aerobic/resistance (intermittent bouts of walking and high-intensity calisthenics), and seated rest on three separate counterbalanced days. Results revealed no changes in Flanker performance (i.e., reaction time and response accuracy) or P3 (latency and mean amplitude) following either HIIE conditions compared to seated rest. Together, these data suggest inhibitory control and neuroelectric underpinnings are not affected by different modalities of HIIE at 30 min and 85 min post-exercise. Such findings reveal that engaging in short bouts of different HIIE modalities for overall health neither improves nor diminishes inhibitory control and brain function for an extended period throughout the day.

Classroom-Based Strategies to Reduce Disparities in Physical Activity Among Children with Asthma.

Children with asthma often experience physical activity (PA) induced symptoms 5-15min following the start of exercise. Classroom PA breaks provide short intermittent bouts of PA and may represent a novel strategy to safely promote PA participation in this clinical population. The purpose of this study was to determine the feasibility of a classroom-based PA intervention, Interrupting Prolonged Sitting with Activity (InPACT), where teachers implement 5 × 4-min moderate-to-vigorous physical activity (MVPA) breaks throughout the school day. Nine classrooms at one elementary-middle school in Detroit, MI (student demographics: 79% Hispanic; 80% on free/reduced lunch; 31% prevalence of asthma and asthma-like symptoms) participated in this 20-week intervention. Asthma status was self-reported via the International Study of Asthma and Allergies in Childhood (ISAAC) Video Questionnaire in conjunction with nurse documentation. PA participation, exercise intensity, and asthmatic symptom occurrence were assessed via direct observation. Students accumulated approximately 17min of activity per day during PA breaks. Compared to students without asthma, a higher percentage of students with asthma participated in MVPA (asthma: 52.9% ± 1.2%; non-asthma: 46.2% ± 0.8%; p = 0.01), a lower percentage participated in light PA (asthma: 25.9% ± 1.0%; non-asthma: 30.1% ± 0.7%; p = 0.01), and sedentary time during activity breaks (asthma: 21.2% ± 0.9%; non-asthma: 23.8% ± 0.7%; p = 0.02). Out of 294 observations, six instances of asthmatic symptoms (coughing) were observed in students with asthma 5-15min following the PA break. Symptoms self-resolved within 15-min of the PA break and did not result in sustained exercise-induced bronchoconstriction. Classroom-based interventions that incorporate short intermittent bouts of PA represent safe exercises for children with asthma and may help to reduce PA disparities in this clinical population.

HIIT and Resistance Training Effects on Learning-related Outcomes in Underserved School Children

Research has demonstrated associations between differing modalities of physical activity (PA) and behavioral and learning outcomes; however, little evidence exists in real world settings. To evaluate the effects of embedding high intensity interval training (HITT) and resistance training (RT) into physical education (PE) curriculum on PA, academic performance, and behavior in youth attending urban schools. Forty boys and 30 girls; ages 8-10 yrs. enrolled in an expanded public school supplemental learning program were assigned into one of three conditions using a pragmatic trial design: standard PE curriculum (n = 23), HITT (n = 25), and RT (n = 22). PA was measured using accelerometers; math achievement scores were conducted at baseline and post-intervention using the Math Knowledge Assessment (MKA); behavior was assessed using the Abbreviated Conners Rating Scale (ACRS) daily. Participation in HITT resulted in 1.86 additional vigorous PA minutes (p=0.04) and 0.76 additional very vigorous PA minutes (P=0.02) per session, but was not associated with increased moderate PA minutes compared to the control group. RT PA outcomes did not differ from regular PE. Participating in HIIT, but not RT, was associated with a 1.82-point improvement in math test scores compared to those in the same grade in the standard PE group (p=0.02). No group assignment was associated with behavioral ratings. Embedding HITT within PE has potential for improving vigorous PA levels and may affect learning outcomes in urban youth. This is consistent with prior studies which show how short bouts of intense exercise can improve cognitive outcomes.

Short inertial sensor-based gait tests reflect perceived state fatigue in multiple sclerosis

BackgroundMultiple sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system, affecting more than 2.3 million people worldwide. Fatigue is among the most common symptoms in MS, resulting in reduced mobility and quality of life. The six-minute walking test (6MWT) is commonly used as a measure of fatigability for the assessment of state fatigue throughout treatment or rehabilitation programs. This ‘gold standard’ test is time-consuming and can be difficult and exhausting for some patients with high levels of disability or high rates of fatigue. Research questionCan short inertial sensor-based gait tests assess perceived state fatigue in MS patients? MethodsSixty-five MS patients equipped with one sensor on each foot performed the 6 min walk test (6MWT) and the 25-foot walk (25FW, at both preferred and fastest speed). Perceived state fatigue was measured after each minute of the 6MWT, using the Borg rating. The highest of these ratings served as a measure of overall perceived state fatigue. Stride-wise spatio-temporal gait parameters were extracted from the 25FW and from the first minute, first 2 min, and first 4 min of the 6MWT. Principal component analysis was performed. Perceived state fatigue was predicted in a regression analysis, using the principal components of gait parameters as predictors. Statistical tests evaluated differences in performance between the full 6MWT, the shortened 6MWT, and the 25FW. ResultsA mean absolute error of less than 2 points on the Borg rating was obtained using the shortened 6MWT and the 25FW. There were no significant differences between the prediction accuracy of the full 6MWT and that of the shortened gait tests. SignificanceIt is possible to use shortened gait tests when evaluating perceived state fatigue in MS patients using inertial sensors. Substituting them for long gait tests may reduce the burden of the testing on both patients and clinicians. Further, the approach taken here may prompt future work to explore the use of short bouts of real-world walking with unobtrusive inertial sensors for state fatigue assessment.

Changes in sedentary behavior patterns during the transition from childhood to adolescence and their association with adiposity: a prospective study based on compositional data analysis

BackgroundTo date, no longitudinal study using a compositional approach has examined sedentary behavior (SB) patterns in relation to adiposity in the pediatric population. Therefore, our aims were to (1) investigate the changes in SB patterns and adiposity from childhood to adolescence, (2) analyze the prospective compositional associations between changes in SB patterns and adiposity, and (3) estimate the changes in adiposity associated with substituting SB with physical activity (PA) of different intensities.MethodsThe study presents a longitudinal design with a 5-year follow-up. A total of 88 participants (61% girls) were included in the analysis. PA and SB were monitored for seven consecutive days using a hip-worn accelerometer. Adiposity markers (fat mass percentage [FM%], fat mass index [FMI], and visceral adiposity tissue [VAT]) were assessed using the multi-frequency bioimpedance analysis. The prospective associations were examined using compositional data analysis.ResultsOver the follow-up period, the proportion of time spent in total SB increased by 154.8 min/day (p < 0.001). The increase in total SB was caused mainly by an increase in middle and long sedentary bouts, as these SB periods increased by 79.8 min/day and 62.0 min/day (p < 0.001 for both), respectively. FM%, FMI, and VAT increased by 2.4% points, 1.0 kg/m2, and 31.5 cm2 (p < 0.001 for all), respectively. Relative to the remaining movement behaviors, the increase in time spent in middle sedentary bouts was significantly associated with higher FM% (βilr1 = 0.27, 95% confidence interval [CI]: 0.02 to 0.53) at follow-up. Lower VAT by 3.3% (95% CI: 0.8 to 5.7), 3.8% (95% CI: 0.03 to 7.4), 3.9% (95% CI: 0.8 to 6.9), and 3.8% (95% CI: 0.7 to 6.9) was associated with substituting 15 min/week spent in total SB and in short, middle, and long sedentary bouts, respectively, with an equivalent amount of time spent in vigorous PA.ConclusionsThis study showed unfavorable changes in SB patterns and adiposity status in the transition from childhood to adolescence. Incorporating high-intensity PA at the expense of SB appears to be an appropriate approach to reduce the risk of excess adiposity in the pediatric population.

Association between patterns of sedentary time and academic performance in adolescents: the mediating role of self-concept.

Objective:To analyze the association between the pattern of sedentary time (bouts and breaks) with academic performance, with an emphasis on the mediating role of self-concept.Methods:Participants in the cross-sectional study were 394 adolescents (208 girls), aged 10–14 years, from sixth grade from Londrina, Paraná, Brazil. The sedentary time pattern was measured through accelerometry. Definitions: sedentary bouts — uninterrupted periods of sedentary behavior; breaks — non-sedentary period between two sedentary bouts. The self-concept was estimated using the Piers-Harris II Inventory. Academic performance was obtained by school grades.Results:Short sedentary bouts were associated with higher academic performance in boys (1–4 minutes: β=0.035, p=0.007) and girls (1–4 minutes: β=0.031, p=0.014; 5–14 minutes: β=0.054, p=0.001). Long bouts (30 minutes) were associated with lower academic performance in boys (β=-0.023; p=0.011) and girls (β=-0.032; p<0.001). For girls, total and intellectual self-concept mediated the association between all sedentary pattern and academic performance (bouts 1–4 minutes [total: 39% and intellectual: 42.8%]; bouts 5–14 minutes [total: 21.5% and intellectual: 35.4%]; bouts ≥30 minutes [total: 22.6% and intellectual: 32.3%]; and breaks [total: 38.9% and intellectual: 40.7%]). For boys, the total (56.4%) and intellectual (82.9%) self-concept mediated only the association between bouts of 5–14 minute and academic performance.Conclusions:The pattern of sedentary time is associated with academic performance in adolescents and this association is mediated by self-concept, especially in girls.

Measuring sedentary behavior using waist- and thigh-worn accelerometers and inclinometers - are the results comparable?

Background:Objective sensor-based quantification of sedentary behavior is an important tool for planning and evaluating interventions for excessive sedentary behavior in patients with musculoskeletal diseases. Although waist-worn accelerometers are the standard for physical activity (PA) assessment, only thigh-worn inclinometers can clearly distinguish sedentary behavior from any light PA or standing activity.Methods:In this study, 53 adults (ages 20–85 years) wore two ActiGraph wGT3X-BT monitors, each containing an inclinometer and accelerometer (set for acquisition of slow movements in all three planes), attached to the right waist and thigh for a period of about 4 days. Both monitors recorded total sedentary time and continuous sedentary 10-min bouts by synchronous accelerometry and inclinometry. Differences and correlations between methods and wearing positions were evaluated against participant age, body mass index (BMI), and number of steps taken. Thigh-worn inclinometry was used as reference.Results:Data from thigh-worn inclinometry and waist-worn accelerometry were highly correlated for total sedentary time [rho = 0.888; intraclass correlation coefficient (ICC) = 0.937] and time in sedentary bouts (rho = 0.818; ICC = 0.848). Nevertheless, accelerometry at the waist underestimated sedentary time by ≈17% (p < 0.001) and time in sedentary bouts by ≈54% (p < 0.001). A satisfactory concordance thus could be demonstrated only for total sedentary time, based on the Bland–Altmann method (≈96% of data within the limits of agreement). The differences between waist-worn accelerometry and thigh-worn inclinometry did not correlate with age but did correlate with BMI and PA for both sedentary behavior parameters (r ⩾ 0.240, p ⩽ 0.043).Conclusion:A waist-worn accelerometer can be used to determine total sedentary time under free-living conditions with sufficient accuracy if the correct settings are chosen. Further investigations are necessary to investigate why short sedentary bouts cannot be reliably assessed.Trial registration:DRKS00024060 (German Clinical Trials Register)

How Biodiversity-Friendly Is Regenerative Grazing?

Regenerative grazing management (ReGM) seeks to mimic natural grazing dynamics to restore degraded soils and the ecological processes underpinning sustainable livestock production while enhancing biodiversity. Regenerative grazing, including holistic planned grazing and related methods, is an adaptive, rotational stocking approach in which dense livestock herds are rotated rapidly through multiple paddocks in short bouts of grazing to defoliate plants evenly and infrequently, interspersed with long recovery periods to boost regrowth. The concentrated “hoof action” of herds in ReGM is regarded vital for regenerating soils and ecosystem services. Evidence (from 58 studies) that ReGM benefits biodiversity is reviewed. Soils enriched by ReGM have increased microbial bioactivity, higher fungal:bacteria biomass, greater functional diversity, and richer microarthropods and macrofauna communities. Vegetation responds inconsistently, with increased, neutral, or decreased total plant diversity, richness of forage grasses and invasive species under ReGM: grasses tend to be favored but shrubs and forbs can be depleted by the mechanical action of hooves. Trampling also reduces numerous arthropods by altering vegetation structure, but creates favorable habitat and food for a few taxa, such as dung beetles. Similarly, grazing-induced structural changes benefit some birds (for foraging, nest sites) while heavy stocking during winter and droughts reduces food for seedeaters and songbirds. With herding and no fences, wildlife (herbivores and predators) thrives on nutritious regrowth while having access to large undisturbed areas. It is concluded that ReGM does not universally promote biodiversity but can be adapted to provide greater landscape habitat heterogeneity suitable to a wider range of biota.