Effects of radiant heat exposure on pacing pattern during a 15-km cycling time trial

Abstract

The goal of this study was to investigate the effects of different durations of skin temperature manipulation on pacing patterns and performance during a 15-km cycling time trial. Nineteen well-trained men completed three 15-km cycling time trials in 18°C and 50% relative humidity with 4.5-km (short-heat), 9.0-km (long-heat) or without (control) radiant heat exposure applied by infrared heaters after 1.5 km in the time trial. During the time trials, power output, mean skin temperature, rectal temperature, heart rate and rating of perceived exertion were assessed. The radiant heat exposure resulted in higher mean skin temperature during the time trial for short-heat (35.0 ± 0.6°C) and long-heat (35.3 ± 0.5°C) than for control (32.5 ± 1.0°C; P < 0.001), whereas rectal temperature was similar (P = 0.55). The mean power output was less for short-heat (273 ± 8 W; P = 0.001) and long-heat (271 ± 9 W; P = 0.02) than for control (287 ± 7 W), but pacing patterns did not differ (P = 0.55). Heart rate was greatest in control (177 ± 9 beats · min^?1; P < 0.001), whereas the rating of perceived exertion remained similar. We concluded that a radiant heat exposure and associated higher skin temperature reduced overall performance, but did not modify pacing pattern during a 15-km cycling time trial, regardless of the duration of the exposure.     

Influence of ski materials on muscle activity

The purpose of this study was to examine whether differences in construction between the compact ski, the racing ski and the soft ski influence the behavioural and electromuscular responses of the user. Eight qualified male ski instructors performed two ‘shuss’ trials and three different basic turns. Six muscles (M. biceps femoris, M. gastrocnemius lateralis and medialis, M. rectus femoris, M. vastus lateralis and M. tibialis anterior) were studied, using a conventional but portable electromyographic (EMG) registration with telemetric synchronization, active electrodes and a six‐channel portable data recorder. Muscle contractions were continuously registered and visualized in raw EMG form and linear envelopes. The differences between the mean rectified EMG data of dynamic contractions while skiing and the mean rectified EMG data of the maximal voluntary contraction were used in the primary analysis of data, from which the participation levels of the muscles investigated could be calculated for each type of ski. Based on this comparison, differences between the effects on muscle activity of the three types of skis were unimportant. In a second phase, the normalized linear envelopes of all subjects were graphically superimposed and averaged. This was performed for each muscle, for each movement, for each leg and for each ski tested. The EMG data were considered in combination with anthropometric values, with snow characteristics and with the velocity of skiing. This study showed systematic differences between the use of the racing, soft and compact ski. On average the soft ski showed the lowest muscle activity patterns and thus the most economical muscular efforts for all muscles investigated and within all movements.     

Measurement of active drag during crawl arm stroke swimming

In order to measure active drag during front crawl swimming a system has been designed, built and tested. A tube (23 m long) with grips is fixed under the water surface and the swimmer crawls on this. At one end of the tube, a force transducer is attached to the wall of the swimming pool. It measures the momentary effective propulsive forces of the hands. During the measurements the subjects’ legs are fixed together and supported by a buoy. After filtering and digitizing the electrical force signal, the mean propulsive force over one lane at constant speeds (ranging from about 1 to 2 m s^‐1) was calculated. The regression equation of the force on the speed turned out to be almost quadratic. At a mean speed of 1.55 m s^‐1 the mean force was 66.3 N. The accuracy of this force measured on one subject at different days was 4.1 N. The observed force, which is equal to the mean drag force, fits remarkably well with passive drag force values as well as with values calculated for propulsive forces during actual swimming reported in the literature. The use of the system does not interfere to any large extent with normal front crawl swimming; this conclusion is based on results of observations of film by skilled swim coaches. It was concluded that the system provides a good method of studying active drag and its relation to anthropometric variables and swimming technique.     

Assessment of curriculum quality through alumni research

In today's output defined society, alumni are the output of higher education. This article shows how alumni research can be used as an important indicator of curriculum quality. This relatively unexplored area of engineering education research in Europe is highlighted using a case study carried out in the Netherlands, the outcomes of which have served as a useful input for curriculum development at the institute where it was carried out.     

Predicting second language writing proficiency: the roles of cohesion and linguistic sophistication

This study addresses research gaps in predicting second language (L2) writing proficiency using linguistic features. Key to this analysis is the inclusion of linguistic measures at the surface, textbase and situation model level that assess text cohesion and linguistic sophistication. The results of this study demonstrate that five variables (lexical diversity, word frequency, word meaningfulness, aspect repetition and word familiarity) can be used to significantly predict L2 writing proficiency. The results demonstrate that L2 writers categorised as highly proficient do not produce essays that are more cohesive, but instead produce texts that are more linguistically sophisticated. These findings have important implications for L2 writing development and L2 writing pedagogy.     

Impact of early code‐skill and oral‐comprehension training on reading achievement in first grade

In a 3‐year longitudinal study, we examined the relationships between oral language development, early training and reading acquisition on word‐identification and reading‐comprehension tests administered to a sample of 687 French children. Hierarchical linear models showed that both phonological awareness and oral comprehension at the age of 4 years were relevant to reading acquisition 2 years later. These two broad skills explained separate parts of the variance on both outcome measures, while revealing opposite effects: phonological skills explained more variance for alphabetic reading skills and oral comprehension explained more variance for reading comprehension. We also assessed the effects of two preschool training programmes focusing on either phonological awareness or comprehension skills. The results showed that phonological awareness training had a positive effect on alphabetic scores, and comprehension training had a positive effect on reading comprehension. These results provide insight into early oral instruction and contribute to the theoretical debate about the linguistic predictors of literacy acquisition.     

Metalinguistic contributions to reading and spelling in second and third grade students

Minimal research has been conducted on the simultaneous influence of multiple metalinguistic, linguistic, and processing skills that may impact literacy development in children who are in the process of learning to read and write. In this study, we assessed the phonemic awareness, morphological awareness, orthographic awareness, receptive vocabulary, and rapid naming abilities of second and third grade students (N?=?56) and determined how these abilities predicted the children??s reading and spelling skills. Regression analyses revealed that morphological awareness was the sole unique contributor to spelling and, together with orthographic awareness, uniquely contributed to word recognition. Morphological awareness also was significantly related to reading comprehension. The results add to a growing literature base providing evidence that early literacy development is influenced by morphological awareness, an ability that has received considerably less educational attention. Additionally, the findings point to the importance of tapping into multiple sources of metalinguistic knowledge when providing instruction in reading and spelling.     

Implementing Eratosthenes’ Discovery in the Classroom: Educational Difficulties Needing Attention

This paper presents a critical analysis of the accepted educational use of the method performed by Eratosthenes to measure the circumference of Earth which is often considered as a relevant means of dealing with issues related to the nature of science and its history. This method relies on a number of assumptions among which the parallelism of sun rays. The assumption of sun rays parallelism (if it is accurate) does not appear spontaneous for students who consider sun rays to be divergent. Here, we propose an educational reconstruction of Eratosthenes?? discovery based on the exploitation of a narrative written by Cleomedes during the first century AD. This implies that the students are involved in an elaboration of parallelism by an approach where the notion of ??approximation?? remains central.     

Instruction Characteristics and Cognitive Achievement of Young Children in Elementary Schools

This ongoing Dutch study into the school careers of young children in elementary schools, facilitated by the Educational Priority Policy, has focused on the influence of school and class organization on linguistic and cognitive development. In this article, the development in word decoding, reading comprehension, and math of 3rd graders (6 years of age) is analyzed. The data are gathered in 28 elementary schools by means of tests, questionnaires, and logbooks. A multilevel analysis shows that for word decoding and reading comprehension differences in development caused by differences in instruction are very small. For math, on the contrary, there is a substantial proportion of variance at the class level. Instruction characteristics and years of experience by the teachers seemed to be important.