Aerobic Responses to FES-Assisted and Volitional Cycling in Children with Cerebral Palsy

Recumbent stationary cycling is a potential exercise modality for individuals with cerebral palsy (CP) that lack the postural control needed for upright exercises. Functional electrical stimulation (FES) of lower extremity muscles can help such individuals reach the cycling intensities that are required for aerobic benefits. The aim of this study was to examine the effect of cycling with and without FES assistance to that of a no-intervention control group on the cardiorespiratory fitness of children with CP. Thirty-nine participants were randomized to a FES group that underwent an 8-week FES-assisted cycling program, the volitional group (VOL), who cycled without FES, or a no-intervention control group (CON) (15 FES, 11 VOL, 13 CON). Cadence, peak VO2, and net rise in heart rate were assessed at baseline, end of training, and washout (8-weeks after cessation of training). Latent growth curve modeling was used for analysis. The FES group showed significantly higher cycling cadences than the VOL and CON groups at POST and WO. There were no differences in improvements in the peak VO2 and peak net HR between groups. FES-assisted cycling may help children with CP attain higher cycling cadences and to retain these gains after training cessation. Higher training intensities may be necessary to obtain improvements in peak VO2 and heart rate.

Longitudinal Impact of Depressive Symptoms and Peer Tobacco Use on the Number of Tobacco Products Used by Young Adults

We examined the role of depressive symptoms in the longitudinal trajectory of the number of tobacco products used across young adulthood, ages 18–30 years, and whether peer tobacco use exacerbated the effects of the depressive symptoms. Participants were 4534 initially 18–25-year-old young adults in the Marketing and Promotions Across Colleges in Texas project (Project M-PACT), which collected data across a 4.5-year period from 2014 to 2019. Growth curve modeling within an accelerated design was used to test study hypotheses. Elevated depressive symptoms were associated with a greater number of tobacco products used concurrently and at least six months later. The number of tobacco-using peers moderated the association between depressive symptoms and the number of tobacco products trajectory. Young adults with elevated depressive symptoms used a greater number of tobacco products but only when they had a greater number of tobacco-using peers. Findings indicate that not all young adults with depressive symptoms use tobacco. Having a greater number of tobacco-using peers may facilitate a context that both models and encourages tobacco use. Therefore, tobacco prevention programs should aim to include peer components, especially for young adults.

Individual Differences and Changes in Self-Reported Work Performance During the Early Stages of the COVID-19 Pandemic

This longitudinal study examines how three dimensions of self-reported work performance, including task proficiency, adaptivity, and proactivity, changed between December 2019 and September 2020 in Germany. Based on event system and transition theories, we expected work performance to decline because of the “lockdown” between early April and early May 2020 and to subsequently increase when restrictions were eased between early May and early September 2020. Additionally, we hypothesized that high levels of core self-evaluations (i. e., employees’ fundamental evaluations about themselves) buffer the decline and strengthen the recovery in work performance. Data were collected from N = 591 full-time employees across eight measurement points. Results based on discontinuous latent growth curve modeling largely supported the expected trajectories in work performance. Moreover, core self-evaluations positively predicted the levels of work performance as well as the slopes indicating recovery in task proficiency and adaptivity, but not proactivity.

Parental Control and Adolescent Delinquency Based on Parallel Process Latent Growth Curve Modeling

Although ample evidence demonstrates parental influences on delinquent behavior in adolescent years, few studies have examined how change in adolescent delinquency and change in parental behavior are related to each other, particularly in late adolescence. This study utilized survey data collected over three high school years (N = 3074 Grade 10 students; mean age = 15.57, SD = 0.74 at Time 1) to examine how change trajectory of adolescent-reported delinquency is related to change trajectory of adolescent perceived parental behavioral and psychological control using parallel process growth curve modeling. Results revealed that adolescent delinquency level was negatively associated with both parents’ behavioral control and positively associated with parents’ psychological control at Time 1 (Grade 10). However, adolescent delinquency increased in parallel with decreased parental behavioral control, but not a change in psychological control. Initial paternal behavioral control positively predicted a linear increase slope of adolescent delinquency while initial adolescent delinquency level also positively predicted a linear decrease slope of paternal behavioral control. These results highlight the parallel development of parents’ behavioral control and children’s delinquent behavior and delineate the reciprocal influence between paternal behavioral control and adolescent children’s delinquency.

How Team Emotions Impact Individual Employee Strain Before, During, and After a Stressful Event: A Latent Growth Curve Modeling Approach

Employee strain is a significant and costly issue for hospitality organizations. This study investigated the change trajectory of strain pre, during, and post a discrete stressful event and how cohesion and group emotional variability altered the shape of the trajectory. Using an experience sampling method approach, we gathered 402 daily observations from 84 workers in a period that included a specific stressful event, the opening of a one-night “theme dinner” restaurant that catered to dinner guests from the general public. We used latent growth curve modeling to investigate the change of strain among employees over time. The results showed that indicators of strain displayed inverted U-shaped trajectories (i.e., strain increased before and decreased after the stressful event) and that group cohesion and emotional variability affected the starting value and the change trajectory of strain. By investigating strain on a daily basis and considering group-based influences in response to discrete stressful events, this study provides significant implications to the hospitality literature and suggestions to hospitality managers on how to alleviate the impact of strain among their workforces.

Longitudinal Designs for Organizational Research

Longitudinal research involves collecting data from the same entities on two or more occasions. Almost all organizational theories outline a longitudinal process in which one or more variables cause a subsequent change in other variables. However, the majority of empirical studies rely on research designs that do not allow for the proper assessment of change over time or the isolation of causal effects. Longitudinal research begins with longitudinal theorizing. With this in mind, a variety of time-based theoretical concepts are helpful for conceptualizing how a variable is expected to change. This includes when variables are expected to change, the form or shape of the change, and how big the change is expected to be. To aid in the development of causal hypotheses, researchers should consider the history of the independent and dependent variables (i.e., how they may have been changing before the causal effect is examined), the causal lag between the variables (i.e., how long it takes for the dependent variable to start changing as a result of the independent variable), as well as the permanence, magnitude, and rate of the hypothesized change in the dependent variable. After hypotheses have been formulated, researchers can choose among various research designs, including experimental, concurrent or lagged correlational, or time series. Experimental designs are best suited for inferring causality, while time series designs are best suited for capturing the specific timing and form of change. Lagged correlation designs are useful for examining the direction and magnitude of change in a variable between measurements. Concurrent correlational designs are the weakest for inferring change or causality. Theory should dictate the choice of design, and designs can be modified and/or combined as needed to address the research question(s) at hand. Next, researchers should pay attention to their sample selection, the operationalization of constructs, and the frequency and timing of measures. The selected sample must be expected to experience the theorized change, and measures should be gathered as often as is necessary to represent the theorized change process (i.e., when the change occurs, how long it takes to unfold, and how long it lasts). Experimental manipulations should be strong enough to produce theorized effects and measured variables should be sensitive enough to capture meaningful differences between individuals and also within individuals over time. Finally, the analytic approach should be chosen based on the research design and hypotheses. Analyses can range from t-test and analysis of variance for experimental designs, to correlation and regression for lagged and concurrent designs, to a variety of advanced analyses for time series designs, including latent growth curve modeling, coupled latent growth curve modeling, cross-lagged modeling, and latent change score modeling. A point worth noting is that researchers sometimes label research designs by the statistical analysis commonly paired with the design. However, data generated from a particular design can often be analyzed using a variety of statistical procedures, so it is important to clearly distinguish the research design from the analytic approach.