The effects of work:rest duration on physiological and perceptual responses during intermittent exercise and performance

In this study, we examined the effects of different work:rest durations during 20 min intermittent treadmill running and subsequent performance. Nine males (mean age 25.8 years, s = 6.8; body mass 73.9 kg, s = 8.8; stature 1.75 m, s = 0.05; VO(2max) 55.5 ml x kg(-1) x min(-1), s = 5.8) undertook repeated sprints at 120% of the speed at which VO(2max) was attained interspersed with passive recovery. The work:rest ratio was constant (1:1.5) with trials involving either short (6:9 s) or long (24:36 s) work:rest exercise protocols (total exercise time 8 min). Each trial was followed by a performance run to volitional exhaustion at the same running speed. Testing order was randomized and counterbalanced. Heart rate, oxygen consumption, respiratory exchange ratio, and blood glucose were similar between trials (P > 0.05). Blood lactate concentration was greater during the long than the short exercise protocol (P < 0.05), whereas blood pH was lower during the long than the short exercise protocol (7.28, s = 0.11 and 7.30, s = 0.03 at 20 min, respectively; P < 0.05). Perceptions of effort were greater throughout exercise for the long than the short exercise protocol (16.6, s = 1.4 and 15.1, s = 1.6 at 20 min, respectively; P < 0.05) and correlated with blood lactate (r = 0.43) and bicarbonate concentrations (r = 0.59; P < 0.05). Although blood lactate concentration at 20 min was related to performance time (r = - 0.56; P < 0.05), no differences were observed between trials for time to exhaustion (short exercise protocol: 95.8 s, s = 30.0; long exercise protocol: 92.0 s, s = 37.1) or physiological responses at exhaustion (P > 0.05). Our results demonstrate that 20 min of intermittent exercise involving a long work:rest duration elicits greater metabolic and perceptual strain than intermittent exercise undertaken with a short work:rest duration but does not affect subsequent run time to exhaustion.     

Children born at risk: What's happening in kindergarten?

Many studies examine the development of infants born at risk for medical and developmental problems during the early years of life, but far fewer follow these children into their school years. This project compared high-risk vs. low-risk children in their performance on the WPPSI at pre- and postkindergarten levels. In general, both groups of children demonstrated increases in performance; however, their patterns of performance were different. The high-risk children showed increases predominantly in the Performance areas of the test, whereas the low-risk children demonstrated increases predominantly in the Verbal areas.     

School phobia and separation anxiety: Diagnostic and treatment comparisons

There exists substantial confusion regarding the comparative diagnostic criteria and treatment implications for school phobia and separation anxiety. A literature survey demonstrates the tendency of school personnel to put all youngsters exhibiting these disorders into one group called “school refusers.” Treatment issues are handled in a similar fashion despite accumulating evidence of treatment-relevant differences between the disorders. Variables that facilitate a finer diagnostic discrimination are presented. After reviewing pertinent treatment distinctions between the two disorders, specific behaviorally oriented methods are recommended.     

A comparison of students who delay kindergarten entry and those who are retained in grades K−5

Retention has been one way that school personnel have dealt with the problem of school failure. Some authors have proposed delayed school entry as an alternative to retention, especially since there are concerns about the effects of retention on students' self-esteem. It is unclear from the literature whether retention and delayed entry have differential outcomes on measures of school success. This study explored whether there were differences in IQ and achievement (at grades 2, 5, and 7) between students who delayed school entry and those who were retained in later elementary grades, as well as any interactions with gender. There was a significant 6-point difference in IQ, favoring the delayed-entry group. Furthermore, when the achievement test scores were analyzed using an ANCOVA with IQ as a covariate, no significant differences were identified for either group or gender. Implications for school practices are provided.     

Animals,Governance and Ecology: Managing the Menace of Venomous Snakes in Colonial India

During the nineteenth century, the British Raj launched a campaign to reduce the number of people killed annually by venomous snakes on the Indian subcontinent. Unlike its successful effort to cull large mammals, the colonial government was forced to abolish its bounty scheme in 1890 and instead seek to use sanitation to reduce interactions between humans and snakes. This article will assess this transition in policy as a means to understand how attitudes towards the governance of animals were shaped by cultural and ecological factors. It will be shown that during its inception, discourses of scientific governance statistically augmented perceptions of the threat posed by snakes, presenting them as a direct yet manageable danger within an anthropocentric cultural model. However, financial and practical limitations forced the government to recognise that the behaviour, seasonal patterns and territorial movements of snakes influenced the rate of mortality, and thus adjust its policy to acknowledge the experience of cohabitation in India’s diverse ecological contexts.     

Kinematic analysis of hip and knee rotation and other contributors to ballet turnout

Turnout, or external rotation (ER) of the lower extremities, is essential in ballet. The purpose of this study was to utilise physical examination and a biomechanical method for obtaining functional kinematic data using hip and knee joint centres to identify the relative turnout contributions from hip rotation, femoral anteversion, knee rotation, tibial torsion, and other sources. Ten female dancers received a lower extremity alignment assessment, including passive hip rotation, femoral anteversion, tibial torsion, weightbearing foot alignment, and Beighton hypermobility score. Next, turnout was assessed using plantar pressure plots and three-dimensional motion analysis; participants performed turnout to ballet first position on both a plantar pressure mat and friction-reducing discs. A retro-reflective functional marker motion capture system mapped the lower extremities and hip and knee joint centres. Mean total turnout was 129±15.7° via plantar pressure plots and 135±17.8° via kinematics. Bilateral hip ER during turnout was 49±10.2° (36% of total turnout). Bilateral knee ER during turnout was 41±5.9° (32% of total turnout). Hip ER contribution to total turnout measured kinematically was less than expected compared to other studies, where hip ER was determined without functional kinematic data. Knee ER contributed substantially more turnout than expected or previously reported. This analysis method allows precise assessment of turnout contributors.     

Changes in kinematics and arm–leg coordination during a 100-m breaststroke swim

The purpose of this study was to compare arm–leg coordination and kinematics during 100 m breaststroke in 26 (8 female; 18 male) specialist breaststroke swimmers. Laps were recorded using three 50-Hz underwater cameras. Heart rate and blood lactate were measured pre- and post-swim. Arm–leg coordination was defined using coordination phases describing continuity between recovery and propulsive phases of upper and lower limbs: coordination phase 1 (time between end of leg kick and start of the arm pull phases); and coordination phase 2 (time between end of arm pull and start of leg kick phases). Duration of stroke phases, coordination phases, swim velocity, stroke length (SL), stroke rate (SR) and stroke index (SI) were analysed during the last three strokes of each lap that were unaffected by turning or finishing. Significant changes in velocity, SI and SL (P < 0.05) were found between laps. Both sexes showed significant increase (P < 0.05) in heart rate and blood lactate pre- to post-swim. Males had significantly (P < 0.01) faster swim velocities resulting from longer SLs (P = 0.016) with no difference in SR (P = 0.064). Sex differences in kinematic parameters can be explained by anthropometric differences providing males with increased propelling efficiency.