UNASSIGNED: Since there is no scientifically validated German version of the Behavioral Regulation in Exercise Questionnaire (BREQ-3), the aim of this study was to assess its psychometric parameters and invariance across sex in a sample of German-speaking young adults. The BREQ-3 is an instrument measuring the social and internal influences of motivation toward exercising. This tool is widespread within the scientific community and has been validated in several languages.
UNASSIGNED: A total of 271 participants (45% women; mean age = 20.67 ± 2.17 years; effect size ≥ 0.5) filled in the BREQ-3 at one time point, with a small sub-sample (n = 37) responding it a second time after 15 days. Confirmatory Factorial Analysis, Structural Modeling, and Intraclass Correlation Coefficient were used to examine the German version of the questionnaire.
UNASSIGNED: Results highlighted a good fit of the six-dimensional model after the removal of two items (CFI = 0.912; SRMR = 0.0594; RMSEA = 0.064), as well as full invariance across sex (pχ2 = 0.218; ΔCFI < 0.01). Internal consistency and reliability were moderate to good.
UNASSIGNED: The 22-item German BREQ-3 is a scientifically valid instrument that can be used in cross-national studies dealing with social aspects of exercise behaviors.

Shear wave elastography (SWE) of human skeletal muscles allows for measurement of muscle elastic properties in vivo and has important applications in sports medicine and for the diagnosis and treatment of muscle-related diseases. Existing methods of SWE for skeletal muscles rely on the passive constitutive theory and have so far been unable to provide constitutive parameters describing muscle active behavior. In the present paper, we overcome this limitation by proposing a SWE method for quantitative inference of active constitutive parameters of skeletal muscles in vivo. To this end, we investigate the wave motion in a skeletal muscle described by a constitutive model in which muscle active behavior has been defined by an active parameter. An analytical solution relating shear wave velocities to both passive and active material parameters of muscles is derived, based upon which an inverse approach has been developed to evaluate these parameters. To demonstrate the usefulness of the reported method, in vivo experiments were carried out on 10 volunteers to obtain constitutive parameters, particularly those describing active deformation behaviors of living muscles. The results reveal that the active material parameter of skeletal muscles varies with warm-up, fatigue and rest. STATEMENT OF SIGNIFICANCE: Existing shear wave elastography methods are limited to imaging the passive parameters of muscles. This limitation is addressed in the present paper by developing a method to image the active constitutive parameter of living muscles using shear waves. We derived an analytical solution demonstrating the relationship between constitutive parameters of living muscles and shear waves. Relying on the analytical solution, we proposed an inverse method to infer active parameter of skeletal muscles. We performed in vivo experiments to demonstrate the usefulness of the theory and method; the quantitative variation of the active parameter with muscle states such as warm-up, fatigue and rest has been reported for the first time.

The active behaviors of pedestrians, such as avoidance motions, affect the resultant injury risk in vehicle-pedestrian collisions. However, the biomechanical features of these behaviors remain unquantified, leading to a gap in the development of biofidelic research tools and tailored protection for pedestrians in real-world traffic scenarios. In this study, we prompted subjects (\"pedestrians\") to exhibit natural avoidance behaviors in well-controlled near-real traffic conflict scenarios using a previously developed virtual reality (VR)-based experimental platform. We quantified the pedestrian-vehicle interaction processes in the pre-crash phase and extracted the pedestrian postures immediately before collision with the vehicle; these were termed the \"pre-crash postures.\" We recorded the kinetic and kinematic features of the pedestrian avoidance responses-including the relative locations of the vehicle and pedestrian, pedestrian movement velocity and acceleration, pedestrian posture parameters (joint positions and angles), and pedestrian muscle activation levels-using a motion capture system and physiological signal system. The velocities in the avoidance behaviors were significantly different from those in a normal gait (p < 0.01). Based on the extracted natural reaction features of the pedestrians, this study provides data to support the analysis of pedestrian injury risk, development of biofidelic human body models (HBM), and design of advanced on-vehicle active safety systems.

In Belgium, lockdown measures were taken to counter the spread of COVID-19. This major life-change event may disrupt a person\'s daily routine and influence health behaviors. Although measures were restrictive, citizens were encouraged to engage in physical activity (PA) behavior in order to maintain well-being. Social support specific to PA (SSPA) had been highlighted as an important psychosocial factor in initiating and/or maintaining active behavior. The main aims of this study were to explore the influence of COVID-19 lockdown on PA and sedentary behavior, and on SSPA from family and from friends; and investigate the potential differences in terms of professional status. An online survey was distributed during the 1st weeks of the lockdown. A total of 272 Belgian adults responded to the survey. The findings show no significant difference between prior to and during lockdown with regard to the amount of PA. The results show a significant increase in sedentary behavior among the entire sample, workers and retirees. The findings also suggest that the support of other individuals is particularly useful for certain population groups such as retirees. Given the importance of the levels of PA and sedentariness as health behaviors preceding a major life-change event such as a lockdown, there is a need to promote these health behaviors during normal life in order for the population to remain active throughout their lifespan.

Starting college or university is a significant life event that can impact students\' physical activity (PA). Social support specific to PA (SSPA) is a social determinant of PA among college and university students. This review had 3 aims: (1) to systematically review studies examining the association between SSPA and PA among students; (2) to examine whether potential associations differed in terms of types or sources of SSPA; and (3) to examine whether any potential associations differed in terms of gender.
Studies were identified using Academic Search Premier, PsycInfo, Sociological Abstracts, and SPORTDiscus.
This review included 25 papers. The results suggested that there is a positive association between SSPA and PA among college and university students. Although the importance of different sources of SSPA is not clear, the results suggested that family and friends provide significant SSPA.
High variability in measurement methods made it difficult to compare studies and to come to a clear consensus. However, the findings suggested that SSPA may be a determinant of PA. In order to better understand the relationship between SSPA and PA among students, some elements, such as gender, socioeconomic level, and off- or on-campus housing, should be considered in future studies.

Biking and walking are active commuting, which is considered an opportunity to create healthy habits.
The purpose of this study was to determine the main environmental and psychosocial barriers perceived by students, leading to less Active Commuting (AC) to university and to not reaching the Physical Activity (PA) recommendations.
In this cross-sectional study, 1349 university students (637 men and 712 women) were selected. A self-reported questionnaire was applied to assess the mode of commuting, PA level and barriers to the use of the AC.
Women presented higher barriers associated with passive commuting than men. The main barriers for women were \"involves too much planning\" (OR: 5.25; 95% CI: 3.14-8.78), \"It takes too much time\" (OR: 4.62; 95% CI: 3.05-6.99) and \"It takes too much physical effort \" (OR: 3.18; 95% CI: 2.05-4.94). In men, the main barriers were \"It takes too much time\" (OR: 4.22; 95% CI: 2.97-5.99), \"involves too much planning\" (OR: 2.49; 95% CI: 1.67-3.70) and \"too much traffic along the route\" (OR: 2.07; 95% CI: 1.47-2.93). Psychosocial barriers were found in both sexes.
Psychosocial and personal barriers were more positively associated with passive commuting than environmental barriers. Interventions at the university are necessary to improve the perception of AC and encourage personal organization to travel more actively.

The tearing of a muscle-tendon complex (MTC) is caused by an eccentric contraction; however, the structures involved and the mechanisms of rupture are not clearly identified. The passive mechanical behavior the MTC has already been modeled and validated with the discrete element method. The muscular activation is the next needed step. The aim of this study is to model the muscle fiber activation and the muscular activation of the MTC to validate their active mechanical behaviors. Each point of the force/length relationship of the MTC (using a parabolic law for the force/length relationship of muscle fibers) is obtained with two steps: 1) a passive tensile (or contractile) test until the desired elongation is reached and 2) fiber activation during a position holding that can be managed thanks to the Discrete Element model. The muscular activation is controlled by the activation of muscle fiber. The global force/length relationship of a single fiber and of the complete MTC during muscular activation is in agreement with literature. The influence of the external shape of the structure and the pennation angle are also investigated. Results show that the different constituents of the MTC (extracellular matrix, tendon), and the geometry, play an important role during the muscular activation and enable to decrease the maximal isometric force of the MTC. Moreover, the maximal isometric force decreases when the pennation angle increases. Further studies will combine muscular activation with a stretching of the MTC, until rupture, in order to numerically reproduce the tearing of the MTC.

In this review article, we highlight several disparate ideas that are linked to changes in brain state (i.e., sleep to arousal, Down to Up, synchronized to de-synchronized). In any discussion of the brain state, we propose that the cortical pyramidal neuron has a central position. EEG recordings, which typically assess brain state, predominantly reflect the activity of cortical pyramidal neurons. This means that the dominant rhythmic activity that characterizes a particular brain state ultimately has to manifest globally across the pyramidal neuron population. During state transitions, it is the long-range connectivity of these neurons that broadcast the resultant changes in activity to many subcortical targets. Structures like the thalamus, brainstem/hypothalamic neuromodulatory systems, and respiratory systems can also strongly influence brain state, and for many decades we have been uncovering bidirectional pathways that link these structures to state changes in the cerebral cortex. More recently, movement and active behaviors have emerged as powerful drivers of state changes. Each of these systems involve different circuits distributed across the brain. Yet, for a system-wide change in brain state, there must be a collaboration between these circuits that reflects and perhaps triggers the transition between brain states. As we expand our understanding of how brain state changes, our current challenge is to understand how these diverse sets of circuits and pathways interact to produce the changes observed in cortical pyramidal neurons.

Active sensing refers to the concept of animals perceiving their environment while involving self-initiated motor acts. As a consequence of these motor acts, this activity produces direct and timely changes in the sensory surface. Is the brain able to take advantage of the precise time-locking that occurs during active sensing? Is the intrinsic predictability present during active sensing, impacting the sensory processes? We conjecture that if stimuli presentation is evoked by a self-initiated motor act, sensory discrimination and timing accuracy would improve. We studied this phenomenon when rats had to locate the position of a brief light stimulus, either when it was elicited by a warning light [passive condition (PC)] or when it was generated by a lever press [active condition (AC)]. We found that during the PC, rats had 66% of correct responses, vs. a significantly higher 77% of correct responses in AC. Furthermore, reaction times reduced from 1,181 ms during AC to 816 ms during PC For the latter condition, the probability of detecting the side of the light stimulus was negatively correlated with the time lag between the motor act and the evoked light and with a 38% reduction on performance per second of delay. These experiment shows that the mechanism that underlies sensory improvement during active behaviors have a constrained time dynamic, where the peak performances occur during the motor act, decreasing proportionally to the lag between the motor act and the stimulus presentation. This result is consistent with the evidence already found in humans, of a precise time dynamic of the improvement of sensory acuity after a motor act and reveals an equivalent process in rodents. Our results support the idea that perception and action are precisely coordinated in the brain.

OBJECTIVE: To study the involvement of NMDA-dependent mechanisms in the development of posttraumatic stress disorder (PTSD) by investigation of the effects induced by NMDA application in olfactory cortex slices of active and passive rats exposed to inescapable water-immersion stress.
METHODS: Wistar rats were selected in behavioral experiments according to their active or passive behavior. Rats were subjected to unavoidable water-immersion stress, and then after 10 days the surviving brain slices (olfactory cortex) were prepared. NMDA-dependent responses were recorded and analyzed after 50 μM NMDA applications on the slices.
CONCLUSIONS: Different changes in NMDA-stimulated amplitudes were detected in brain slices of rats depending on their passive or active behavior during the formation of PTSD. NMDA responses in the brains of rats with active behavioral strategy were more resistant to stress. Their activity was inhibited, but not blocked. In rats with passive behavior strategies, NMDA-dependent mechanisms were more vulnerable that was manifested as prominent depression of their activity.
Цель исследования. Изучение вклада NMDA-зависимых механизмов в развитие посттравматического стрессового расстройства (ПТСР) путем исследования эффектов, индуцируемых аппликацией агониста NMDA-рецептора на переживающие срезы мозга активных и пассивных крыс, подвергнутых неизбегаемому водно-иммерсионному воздействию. Материал и методы. Крысы линии Вистар были распределены на две группы в поведенческих опытах по признаку активной и пассивной стратегии поведения. Их подвергали неизбегаемому водно-иммерсионному воздействию, а затем спустя 10 дней из их мозга были приготовлены переживающие срезы обонятельной коры. На срезах проводилась регистрация и анализировалась динамика NMDA-зависимых механизмов на аппликацию агониста NMDA-рецептора в концентрации 50 мкМ. Результаты и заключение. Были выявлены различные изменения амплитуд NMDA-стимулируемых постсинаптических ответов в срезах мозга крыс с активной и пассивной стратегиями поведения при формировании ПТСР. NMDA-стимулируемые ответы в мозге крыс с активной стратегией поведения были более устойчивыми к действию стресса. Их амплитуда снижалась, но не блокировалась. У крыс с пассивной стратегией поведения NMDA-зависимые механизмы были более уязвимыми, что проявлялось в выраженном угнетении их активности.