To question the relation between uni- and bipedal postural skills, 21 subjects were required to stand on a force platform through uni- and bipedal conditions. These two protocols are commonly used paradigms to assess the balance capacities of healthy and disabled patients. The recorded displacements of the center of pressure (CP) were decomposed along mediolateral and anteroposterior axes and assessed through variance positions and parameters obtained from fractional Brownian motion (fBm) modeling to determine the nature and the spatiotemporal organization of the successive controlling mechanisms. The variances underline the relative independence of the two tasks. Nevertheless, as highlighted by the fBm framework, postural correction is initiated for the unipedal stance after shorter time delays and longer covered distances. When compared to bipedal standing, one of the main characteristics of unipedal standing is to induce better-controlled CP trajectories, as deduced from the scaling regimes computed from the fBm modeling. Lastly, the control of the CP trajectories during the shortest time intervals along the anteroposterior axis appears identical for both uni- and bipedal conditions. Unipedal and bipedal standing controls should thus be viewed as two complementary tasks, each providing specific and complementary insights into the postural control organization.
Cyril Burdet and Patrice Rougier
W. Neil Widmeyer, Lawrence R. Brawley and Albert V. Carron
Although group size has been one of the most frequently examined small-group variables, it has rarely been studied in sport. In Study 1 the effects of number of team members on cohesion and performance were examined. Teams of 3, 6, and 9 members participated in a 3-on-3 basketball league. Discriminant function analyses indicated that team size was related to pre-and postseason task cohesion and postseason social cohesion. Study 2 determined effects of action-unit size (number from one team on the field of action) on enjoyment and cohesion. Relationships between these outcomes and five more immediate outcomes were also investigated. As predicted, enjoyment and cohesion decreased as size increased. This decrease was also observed for the more immediate outcomes of exercise/fatigue, influence/responsibility, and organization/strategy whereas feelings of crowding increased with size. The best predictor of enjoyment was exercise/fatigue in smaller units and reduced influence/responsibility in large units. Organization/strategy was the best predictor of cohesion for all action-unit sizes.
Nicolas Fabre, Stéphane Perrey, Loïc Arbez and Jean-Denis Rouillon
This study aimed (1) to determine whether paced breathing (synchronization of the expiration phase with poling time) would reduce the metabolic rate and dictate a lower rate of perceived exertion (RPE) than does spontaneous breathing and (2) to analyze the effects of paced breathing on poling forces and stride-mechanics organization during roller-ski skating exercises.
Thirteen well-trained cross-country skiers performed 8 submaximal roller-skiing exercises on a motorized driven treadmill with 4 modes of skiing (2 skating techniques, V2 and V2A, at 2 exercise intensities) by using 2 patterns of breathing (unconscious vs conscious). Poling forces and stride-mechanics organization were measured with a transducer mounted in ski poles. Oxygen uptake (VO2) was continuously collected. After each bout of exercise RPE was assessed by the subject.
No difference was observed for VO2 between spontaneous and paced breathing conditions, although RPE was lower with paced breathing (P < .05). Upper-limb cycle time and recovery time were significantly (P < .05) increased by paced breathing during V2A regardless of the exercise intensity, but no changes for poling time were observed. A slight trend of increased peak force with paced breathing was observed (P = .055).
The lack of a marked effect of paced breathing on VO2 and some biomechanical variables could be explained by the extensive experience of our subjects in cross-country skiing.
Katharina Diehl, Ansgar Thiel, Stephan Zipfel, Jochen Mayer, Alexia Schnell and Sven Schneider
The authors’ aim was to examine the prevalence of (daily) dietary-supplement (DS) use among elite adolescent athletes and to differentiate use by different types of DS according to their function. Data were analyzed for associations between users of these DS types, sociodemographic, sport-specific characteristics, and opinion on the need for DS. In addition, sources of supply and information were examined. In the framework of the GOAL Study, 1,138 German elite adolescent athletes (14–18 yr) answered questions about DS. The data were analyzed to identify groups at risk for using DS after a classification by supplemental function. Of the young athletes, 91.1% reported DS use during the previous month. (Daily) DS use was significantly associated with sex, kind of sport, and the weekly duration of sporting activity. Furthermore, some athletes were required to use DS by their sporting organization. DS use was more likely in these athletes than in those whose sporting organizations had no such requirement. Overall, DS with short- and long-term supplemental function were mostly associated with the use of magnesium. However, DS with medium-term muscle-building function played an important role among daily users. The main source of information about DS was coaches; main source of supply was parents. Professional education is urgently needed, as 9 out of 10 athletes used DS, and strong positive opinions toward the use of DS were present, particularly in the DS users.
Gretchen Kerr, Anthony Battaglia and Ashley Stirling
, & DeSouza, 2012 ). Organizational polices, the ways that programs are designed and delivered, and the nature and quality of the interactions that youth athletes have with coaches, parents, and peers all influence the optimization of positive development outcomes in the sport domain ( Fraser-Thomas et
Jennifer L. Copeland
the population, and by the year 2050 there will be more than 2 billion older adults globally ( World Health Organization [WHO], 2015 ). Furthermore, they are more sedentary than any other age group ( Colley et al., 2011 ; Matthews et al., 2012 ). A systematic review of studies from 10 countries found
C. Jessie Jones and Janie Clark
Because of the recognized value of exercise for older adults, senior fitness programs have been developed in various facilities throughout the United States and in many other countries. However, there appears to be a shortage of professionally trained senior fitness specialists to develop and instruct such programs. A number of professional health and fitness organizations/associations and individual entrepreneurs have developed training programs leading to some type of certification. However, because there are no published curriculum standards to guide the development of these training programs, they often lack components essential for teaching students how to instruct safe and effective classes for senior participants. Curriculum Standards to Prepare Senior Fitness Instructors, developed by a national coalition, were presented at the 1995 International Conference on Aging and Physical Activity in Colorado. This project was undertaken not to promote national certification or licensing but, rather, to help educators plan training programs. Input from the conferees was synthesized into the standards, which are provided in this paper.
Beth Steel, P. Chelladurai and Barbara A. Brown
Gender differences in managerial aspirations and managerial potential have been advanced as possible explanations for the structuring of organizations along gender lines, with women concentrated in lower level jobs and under-represented in managerial positions. These hypothesized gender differences were examined in a sample of male and female physical education and non-physical education students. Analysis of variance results showed that the effects of gender, faculty, or their interaction on managerial aspirations were not significant. The main effects of aspiration level, faculty, and gender on the set of managerial potential variables were significant. Aspirants scored higher than nonaspirants on self-assurance, decisiveness, and need for dominance. Non-physical education students scored higher on need for dominance than did physical education students. Males were higher in need for autonomy and need for dominance, while females were higher in decisiveness.
Brian C. Martinson, A. Lauren Crain, Nancy E. Sherwood, Marcia G. Hayes, Nicolaas P. Pronk and Patrick J. O’Connor
To assess the representativeness of older adults recruited to a physical activity maintenance RCT by conducting sequential comparisons to characterize study sample composition changes occurring between sampling frame construction and study enrollment.
Study subjects (N = 1049) were 50 to 70 year old men and women who had increased physical activity within the past year recruited from a Midwestern managed care organization.
Those responding to an initial mailed screener differed on demographic, behavioral, and SES characteristics from those not responding. Compared with ineligibles, eligible individuals were significantly younger, more highly educated, and more likely to report improved health in the prior year. Compared with eligible individuals who did not enroll, enrollees had generally higher education and income.
Physical activity promotion programs in older adults may have limited reach and substantial volunteer bias. Additional strategies to increase the reach of physical activity interventions into the target population are needed.
Daniela Mattos, Joshua Kuhl, John P. Scholz and Mark L. Latash
The concept of motor equivalent combinations of arm muscles, or M-modes, was investigated during reaching to insert a pointer into a cylindrical target with and without an elbow perturbation. Five M-modes across 15 arm/scapula muscles were identified by principal component analysis with factor extraction. The relationship between small changes in the M-modes and changes in the position/orientation of the pointer were investigated by linear regression analyses. The results revealed a motor equivalent organization of the M-modes for perturbed compared with nonperturbed reaches, both with respect to hand position and orientation, especially in the first 100-ms postperturbation. Similar findings were obtained for motor equivalence computed based on changes in the joint configuration, although the kinematically defined motor equivalence was stronger for pointer orientation. The results support the hypothesis that the nervous system organizes muscles into M-modes and flexibly scales M-mode activation to preserve stable values of variables directly related to performance success.