Perceived exertion under conditions of sustained work and sleep loss

Abstract

The rated perceived exertion (RPE) for treadmill walking carrying a 22 kg pack was measured in two studies with heart rate, workload and psychological measures. Study 1 used an initial treadmill speed and grade producing 40% of maximal oxygen consumption. Exercise subjects walked 1/2-h, then did other tasks for 20-h for 16 sessions on two 20 h long days. Group I had a 4 h nap, while Group 2 had 4 h of rest between workdays. Subjects maintained the 40% workload throughout the two days with a 3 h nap between days, one group starting exercise at midnight and one at noon.

A steady increase in RPE over the sessions each day was found in each study. There were no differences in RPE between the Nap and Rest groups in Study 1 or between the midnight and noon groups in Study 2. RPE was higher on Day 2 in each study. RPE correlated significantly with heart rate, distance walked or elevation at most time periods on the first workday in Study 1, but not Study 2. RPE was positively correlated with fatigue, symptoms, sleepiness and negative mood, and negatively correlated with vigor at most of the time periods day 1 in Study 2; with similar significant correlations at only one time period on day 1, Study 1. RPE was lower the first session Day 2 as compared to the last session Day 1 in both studies. This pre-post break recovery did not differ between groups in either study.     

French and Swedish teachers' social representations of social workers

Collaboration on children at risk is essential, but our knowledge about inter-professional collaboration between social workers and educators is limited. The aim of this study is twofold: (1) to describe French and Swedish teachers' social representation of social workers; and (2) to compare these social representations. The French sample group is composed of 77 secondary school teachers (of students from 11 to 18 years old), and the Swedish sample group is composed of 94. The method used was a ‘free association task’, commonly used to access the semantic content of social representation. Two different social representations of social workers were revealed, one for the French and one for the Swedish teachers. The French representation is characterised by highly positive aspects such as support, listening and competence. Swedish teachers' social representation of social workers is completely different: negative associations were common (44%), and among these, professional secrecy and law and regulations dominated. One plausible explanation is the difference of French and Swedish teachers' roles regarding collaboration with social workers.     

Exceptions to High School Dropout Predictions in a Low-Income Sample: Do Adults Make a Difference?

Adult–child relationship factors were examined to determine whether they differentiated between individuals who follow expected versus unexpected educational pathways. Low-income participants (96 men, 83 women) in the United States were followed from birth through age 23. Individuals were identified who followed expected versus unexpected pathways to high school graduation or dropping out based on academic achievement and behavioral problems. Patterns of parental involvement in school were significantly different between expected dropouts and unexpected graduates in middle childhood. In contrast, expected graduates had higher levels of parent involvement in middle childhood, more supportive parent–child relationships in early adolescence, and higher levels of social competence with adults than unexpected dropouts .     

Properties of two tests for outliers in multivariate data

Mardia's multivariate kurtosis and the generalized distance have desirable properties as multivariate outlier tests. However, extensive critical values have not been published heretofore. A published approximation formula for critical values of the kurtosis is shown to inadequately control the type I error rate, with observed error rates often differing from their intended values by a factor of two or more. Critical values derived from simulations for both tests for up to 25 dimensions and 500 observations are presented. The power curves of both tests are discussed. The generalized distance is the more powerful test when exactly one outlier is present and the contaminant is substantially mean-shifted. However, as the number of outliers increases, the kurtosis becomes the more powerful test. The two tests are compared with respect to power and vulnerability to masking. Recommendations for the use of these tests and interpretation of results are given.     

Perceived exertion under conditions of sustained work and sleep loss

The rated perceived exertion (RPE) for treadmill walking carrying a 22 kg pack was measured in two studies with heart rate, workload and psychological measures. Study 1 used an initial treadmill speed and grade producing 40% of maximal oxygen consumption. Exercise subjects walked 1/2-h, then did other tasks for 20-h for 16 sessions on two 20 h long days. Group I had a 4 h nap, while Group 2 had 4 h of rest between workdays. Subjects maintained the 40% workload throughout the two days with a 3 h nap between days, one group starting exercise at midnight and one at noon.

A steady increase in RPE over the sessions each day was found in each study. There were no differences in RPE between the Nap and Rest groups in Study 1 or between the midnight and noon groups in Study 2. RPE was higher on Day 2 in each study. RPE correlated significantly with heart rate, distance walked or elevation at most time periods on the first workday in Study 1, but not Study 2. RPE was positively correlated with fatigue, symptoms, sleepiness and negative mood, and negatively correlated with vigor at most of the time periods day 1 in Study 2; with similar significant correlations at only one time period on day 1, Study 1. RPE was lower the first session Day 2 as compared to the last session Day 1 in both studies. This pre-post break recovery did not differ between groups in either study.