Effect of a novel pedal design on maximal power output and mechanical efficiency in well-trained cyclists

Abstract

In this study, we evaluated the effects of a novel pedal design, characterized by a downward and forward shift of the cleat fixing platform relative to the pedal axle, on maximal power output and mechanical efficiency in 22 well-trained cyclists. Maximal power output was measured during a series of short (5-s) intermittent sprints on an isokinetic cycle ergometer at cadences from 40 to 120 rev · min^?1. Mechanical efficiency was evaluated during a submaximal incremental exercise test on a bicycle ergometer using continuous [Vdot]O₂ and [Vdot]CO₂ measurement. Similar tests with conventional pedals and the novel pedals, which were mounted on the individual racing bike of the participant, were randomized. Maximal power was greater with novel pedals than with conventional pedals (between 6.0%, s_x  = 1.5 at 40 rev · min^?1 and 1.8%, s_x  = 0.7 at 120 rev · min^?1; P = 0.01). Torque production between crank angles of 60° and 150° was higher with novel pedals than with conventional pedals (P = 0.004). The novel pedal design did not affect whole-body [Vdot]O₂ or [Vdot]CO₂. Mechanical efficiency was greater with novel pedals than with conventional pedals (27.2%, s_x  = 0.9 and 25.1%, s_x  = 0.9% respectively; P = 0.047; effect size = 0.9). In conclusion, the novel pedals can increase maximal power output and mechanical efficiency in well-trained cyclists.     

Sympathoadrenal and parasympathetic responses to exercise

Exhaustive exercise is associated with a persistent sensation of weakness and sometimes nausea suggesting abdominal vagal activity. We measured plasma indices of sympathoadrenal (adrenaline, noradrenaline, dopamine) and vagal (pancreatic polypeptide) activity before, during and after submaximal and maximal exercise in healthy young subjects. Plasma adrenaline, noradrenaline and dopamine increased to 8.5 (range 7.4–40.5), 48.0 (32.3–100.5) and 1.8 (1.2–6.6) nmol l^–1 respectively (n = 5), during maximal exercise and decreased towards control values within 15 min of rest. Pancreatic polypeptide (n = 10) increased only during maximal exercise and reached its highest value, 48 (21–145) pmol l^–1, after exertion. The results conform to an increase in sympathetic activity during exercise and a persistent vagal activity after intense exercise which could contribute to the sensation of weakness.     

Depth of lexical knowledge among bilingual children: the impact of schooling

The majority of studies examining the language and literacy skills of second generation immigrant bilingual children have focused on the breadth of lexical knowledge in populations with a low level of involvement in literacy activities. This study extends previous work in three ways. First, we focused on a sample of second generation immigrant bilingual children from favorable socio-cultural backgrounds. Second, we examined whether these children show lexical knowledge gaps in their second language on various measures of breadth and depth, as compared to their monolingual peers. Finally, we asked whether this gap tends to increase, remain stable, or decrease with formal schooling. Bilingual (n?=?70) and monolingual (n?=?55) children between the ages of 7 and 8?years were evaluated on measures of depth and breadth of lexical knowledge in the second language of the bilingual group. Both groups were tested twice: at the beginning of second grade and at the beginning of third grade. The findings indicate a significant gap between the target groups with respect to most measures of both depth and breadth at the beginning of second grade. However, after a year of schooling, the bilingual children showed significant progress in their lexical knowledge in their second language. The discussion addresses theoretical and clinical implications of these findings.     

Needs Assessments: An Integrated Assignment in Civic Service

An undergraduate social work program developed a service‐learning experience in partnership with a local United Way organization to complete a community needs assessment project. The experience integrated the curricula of a social work research methods course and a generalist‐macro practice course with the principles and actions of experiential and service‐ learning, evidence based practice, and civic responsibility. This integrated curricula project yielded practical, “real world” outcomes for the local community and learning outcomes for the students. Needs assessments conducted by social students resulted in particular groups of community citizens receiving targeted services from agencies receiving funding from United Way. Evidence obtained from the students who participated in this experience indicates that two important learning outcomes were achieved; a heightened awareness of the local community's resource system and a sense of connection to the local community, along with the enhancement of students ‘self‐esteem and increased self‐confidence in their abilities.     

Sound Stuff? Naïve materialism in middle‐school students’ conceptions of sound

Few studies have dealt with students’ preconceptions of sounds. The current research employs Reiner et al. (2000 Reiner, M., Slotta, J. D., Chi, M. T. H. and Resnick, L. B. 2000. Naïve physics reasoning: A commitment to substance‐based conceptions. Cognition and Instruction, 18(1): 1–34. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) substance schema to reveal new insights about students’ difficulties in understanding this fundamental topic. It aims not only to detect whether the substance schema is present in middle school students’ thinking, but also examines how students use the schema’s properties. It asks, moreover, whether the substance schema properties are used as islands of local consistency or whether one can identify more global coherent consistencies among the properties that the students use to explain the sound phenomena. In‐depth standardized open‐ended interviews were conducted with ten middle school students. Consistent with the substance schema, sound was perceived by our participants as being pushable, frictional, containable, or transitional. However, sound was also viewed as a substance different from the ordinary with respect to its stability, corpuscular nature, additive properties, and inertial characteristics. In other words, students’ conceptions of sound do not seem to fit Reiner et al.’s schema in all respects. Our results also indicate that students’ conceptualization of sound lack internal consistency. Analyzing our results with respect to local and global coherence, we found students’ conception of sound is close to diSessa’s “loosely connected, fragmented collection of ideas.” The notion that sound is perceived only as a “sort of a material,” we believe, requires some revision of the substance schema as it applies to sound. The article closes with a discussion concerning the implications of the results for instruction.     

Assessment of Mathematical Concepts of Five-Year-Old Children

An instrument, the Schwartz Early Mathematics Inventory (SEMI), was devised to assess, by means of group administration, the mathematical achievement of children ages 3 through 5. The data presented concern only the first stages of the process and deal only with 215 kindergartners. A reliability of . 94 was obtained on the eighty-one items administered on 64 pages. The mean for items correct 43. 2. The proportion of correct responses for various items ranged from . 85 to . 12. The children had satisfactorily acquired the physical and emotional attributes necessary for completing the inventory, namely, holding a pencil or crayon, turning pages, recording responses in designated areas, and maintaining satisfactory attention for the 12 to 28 minutes required for administering each of the three portions of the SEMI.     

Comprehensive School-Based Physical Activity Promotion: A Review

Physical activity (PA) participation levels among youth remain well below national recommendations. Thus, a variety of strategies to promote youth PA have been advocated, including multifaceted, school-based approaches. One identified as having great potential is a comprehensive school physical activity program (CSPAP). The goal of a CSPAP is to develop a school culture conducive to promoting lifelong PA across five integral components, each serving as a plausible point of intervention: (a) physical education, (b) PA during school, (c) PA before and after school, (d) staff involvement, and (e) family/community involvement. The purpose of this article is to provide an up-to-date review on all CSPAP components, propose the potential of such comprehensive interventions in increasing youth PA levels, and provide future directions for CSPAP research.     

Three Stages of a School'S Moral Development

Through alternating waves of popular enthusiasm and disillusionment with formal development programs, the Talmud Torah of St. Paul Day School has persisted in its commitment to moral education. A review of the Day School's own stages of development and the development of its ethics curriculum over the past fifteen years may prove useful to other schools considering a similar commitment.     

Developmental Trajectories of Acculturation in Hispanic Adolescents: Associations With Family Functioning and Adolescent Risk Behavior

This study examined longitudinal acculturation patterns, and their associations with family functioning and adolescent risk behaviors, in Hispanic immigrant families. A sample of 266 Hispanic adolescents (M_age = 13.4) and their primary parents completed measures of acculturation, family functioning, and adolescent conduct problems, substance use, and sexual behavior at five timepoints. Mixture models yielded three trajectory classes apiece for adolescent and parent acculturation. Assimilated adolescents reported the poorest family functioning, but adolescent assimilation negatively predicted adolescent cigarette smoking, sexual activity, and unprotected sex indirectly through family functioning. Follow‐up analyses indicated that discrepancies between adolescent and parent family functioning reports predicted these adolescent outcomes. Results are discussed regarding acculturation trajectories, adolescent risk behavior, and the mediating role of family functioning.