This review summarizes the research relating physical activity to aerobic fitness among adolescents. A brief description of commonly used physical activity and aerobic fitness measures is presented, followed by an interpretation of the literature that suggests a small to moderate relationship between physical activity and aerobic fitness in this population (typical correlation of .16-17). Dose-response data are lacking, which makes it difficult to offer definitive conclusions concerning the amount of physical activity necessary to elicit change in aerobic capacity. Nevertheless, recommendations about the type, amount, and quality of physical activity for adolescents are presented. Recommendations are based on a summary of the research data on daily physical activity and aerobic fitness in adolescents. Further research is needed to investigate the association between habitual physical activity and aerobic fitness in adolescents where the a priori goal is to identify a threshold of daily physical activity necessary for an aerobic benefit associated with enhanced health.
James R. Morrow Jr. and Patty S. Freedson
Popi Sotiriadou, Jessie Brouwers, Veerle De Bosscher and Graham Cuskelly
Previous studies acknowledge the importance of sporting organizations’ developing partnerships with clubs for athlete development purposes. However, there are no studies that address the way partnerships influence athlete progression and pathways. This study explores interorganizational relationships (IORs) between a tennis federation and tennis clubs in their efforts to improve player development processes. Document analysis and semistructured interviews with representatives from clubs and the Flemish federation were used. The findings show that the federation and the clubs engaged in IORs to achieve reciprocity and efficiency. The federation anticipated gaining legitimacy and asymmetry, and clubs expected to develop stability. Formal and informal control mechanisms facilitated IOR management. The conceptual model discussed in this study shows the types of IOR motives, management, and control mechanisms that drive and influence the attraction, retention/ transition, and nurturing processes of athlete development.
Paul Estabrooks and Kerry S. Courneya
The purpose of the study was to determine if exercise self-schema predicts exercise participation and moderates the exercise intention-behavior relationship. Participants were undergraduate students categorized into exerciser schematics (n = 527), nonexerciser schematics (n = 52), and aschematics (n = 106). The first of two questionnaires, given 4 weeks apart, included intention items for moderate and strenuous exercise, and exercise at university facilities. The second questionnaire included self-reported exercise items. Attendance at the university fitness facilities was monitored during the 4-week period between questionnaires. Kruskal-Wallis tests determined exerciser schematics reported intending to and exercising more often than aschematics and nonexerciser schematics for all measures (p < .01). Fischer z transformations revealed partial support for the hypothesis that exerciser schematics would have a higher correlation between intention and exercise than aschematics or nonexerciser schematics. Discussion focused on overcoming schematic assessment problems, offered explanation of results, and proposed future exercise self-schema research.
Roozbeh Naemi, Stelios G. Psycharakis, Carla McCabe, Chris Connaboy and Ross H. Sanders
Glide efficiency, the ability of a body to minimize deceleration over the glide, can change with variations in the body’s size and shape. The purpose of this study was to investigate the relationships between glide efficiency and the size and shape characteristics of swimmers. Eight male and eight female swimmers performed a series of horizontal glides at a depth of 70 cm below the surface. Glide efficiency parameters were calculated for velocities ranging from 1.4 to 1.6 m/s for female swimmers (and at the Reynolds number of 3.5 million) and from 1.6 to 1.8 m/s for male swimmers (and at the Reynolds number of 4.5 million). Several morphological indices were calculated to account for the shape characteristics, with the use of a photogrammetric method. Relationships between the variables of interest were explored with correlations, while repeated-measures ANOVA was used to assess within-group differences between different velocities for each gender group. Glide efficiency of swimmers increased when velocity decreased. Some morphological indices and postural angles showed a significant correlation with glide efficiency. The glide coefficient was significantly correlated to the chest to waist taper index for both gender groups. For the male group, the glide coefficient correlated significantly to the fineness ratio of upper body, the chest to hip cross-section. For the female group the glide coefficient had a significant correlation with the waist to hip taper index. The findings suggested that gliding efficiency was more dependent on shape characteristics and appropriate postural angles rather than being dependent on size characteristics.
Simon Avrillon, Boris Jidovtseff, François Hug and Gaël Guilhem
Muscle strengthening is commonly based on the use of isoinertial loading, whereas variable resistances such as pneumatic loading may be implemented to optimize training stimulus. The purpose of the current study was to determine the effect of the ratio between pneumatic and isoinertial resistance on the force–velocity relationship during ballistic movements.
A total of 15 participants performed 2 concentric repetitions of ballistic bench-press movements with intention to throw the bar at 30%, 45%, 60%, 75%, and 90% of the maximal concentric repetition with 5 resistance ratios including 100%, 75%, 50%, 25%, or 0% of pneumatic resistance, the additional load being isoinertial. Force-, velocity-, and power-time patterns were assessed and averaged over the concentric phase to determine the force–velocity and power–velocity relationships for each resistance ratio.
Each 25% increase in the pneumatic part in the resistance ratio elicited higher movement velocity (+0.11 ± 0.03 m/s from 0% to 80% of the concentric phase) associated with lower force levels (–43.6 ± 15.2 N). Increased isoinertial part in the resistance ratio resulted in higher velocity toward the end of the movement (+0.23 ± 0.01 m/s from 90% to 100%).
The findings show that the resistance ratio could be modulated to develop the acceleration phase and force toward the end of the concentric phase (pneumatic-oriented resistance). Inversely, isoinertial-oriented resistance should be used to develop maximal force and maximal power. Resistance modality could, therefore, be considered an innovative variable to modulate the training stimulus according to athletic purposes.
Andrew A. Dingley, David B. Pyne and Brendan Burkett
To characterize relationships between propulsion, anthropometry, and performance in Paralympic swimming.
A cross-sectional study of swimmers (13 male, 15 female) age 20.5 ± 4.4 y was conducted. Subject locomotor categorizations were no physical disability (n = 8, classes S13–S14) and low-severity (n = 11, classes S9–S10) or midseverity disability (n = 9, classes S6–S8). Full anthropometric profiles estimated muscle mass and body fat, a bilateral swim-bench ergometer quantified upper-body power production, and 100-m time trials quantified swimming performance.
Correlations between ergometer mean power and swimming performance increased with degree of physical disability (low-severity male r = .65, ±0.56, and female r = .68, ±0.64; midseverity, r = .87, ±0.41, and r = .79, ±0.75). The female midseverity group showed nearperfect (positive) relationships for taller swimmers’ (with a greater muscle mass and longer arm span) swimming faster, while for female no- and low-severity-disability groups, greater muscle mass was associated with slower velocity (r = .78, ±0.43, and r = .65, ±0.66). This was supported with lighter females (with less frontal surface area) in the low-severity group being faster (r = .94, ±0.24). In a gender contrast, low-severity males with less muscle mass (r = -.64, ±0.56), high skinfolds (r = .78, ±0.43), a longer arm span (r = .58, ±0.60) or smaller frontal surface area (r = -.93, ±0.19) were detrimental to swimming-velocity production.
Low-severity male and midseverity female Paralympic swimmers should be encouraged to develop muscle mass and upper-body power to enhance swimming performance. The generalized anthropometric measures appear to be a secondary consideration for coaches.
Kris Beattie, Brian P. Carson, Mark Lyons and Ian C. Kenny
Maximum- and reactive-strength qualities both have important roles in athletic movements and sporting performance. Very little research has investigated the relationship between maximum strength and reactive strength. The aim of this study was to investigate the relationship between maximum-strength (isometric midthigh-pull peak force [IMTP PF]) and reactive-strength (drop-jump reactive-strength index [DJ-RSI]) variables at 0.3-m, 0.4-m, 0.5-m, and 0.6-m box heights. A secondary aim was to investigate the between- and within-group differences in reactive-strength characteristics between relatively stronger athletes (n = 11) and weaker athletes (n = 11). Forty-five college athletes across various sports were recruited to participate in the study (age, 23.7 ± 4.0 y; mass, 87.5 ± 16.1 kg; height, 1.80 ± 0.08 m). Pearson correlation results showed that there was a moderate association (r = .302–.431) between maximum-strength variables (absolute, relative, and allometric scaled PF) and RSI at 0.3, 0.4, 0.5 and 0.6 m (P ≤ .05). In addition, 2-tailed independent-samples t tests showed that the RSIs for relatively stronger athletes (49.59 ± 2.57 N/kg) were significantly larger than those of weaker athletes (33.06 ± 2.76 N/kg) at 0.4 m (Cohen d = 1.02), 0.5 m (d = 1.21), and 0.6 m (d = 1.39) (P ≤ .05). Weaker athletes also demonstrated significant decrements in RSI as eccentric stretch loads increased at 0.3-m through 0.6-m box heights, whereas stronger athletes were able to maintain their reactive-strength ability. This research highlights that in specific sporting scenarios, when there are high eccentric stretch loads and fast stretch-shortening-cycle demands, athletes’ reactive-strength ability may be dictated by their relative maximal strength, specifically eccentric strength.
Freja Gheysen, Karel Herman and Delfien Van Dyck
environmental factors and PA will be present in older adults with lower cognitive functioning than in their counterparts with higher cognitive functioning. So, the first aim of this study was to examine whether the relationship between neighborhood environmental factors and PA is moderated by overall cognitive
Judith A. Bischoff, Sharon Ann Plowman and Lawrence Lindenman
The purpose of this study was to determine the relationship between teacher fitness and teacher/student interaction in the classroom. Eighteen experienced high school teachers volunteered as subjects. Subjects were divided into high-fit (HF) and low-fit (LF) categories by comparison with norms for their age and sex in sit-ups, sit-and-reach, percent body fat, and maximal aerobic power. Teacher/student classroom interaction was evaluated by coding audiotapes with the verbal portion of Cheffers’ Adaptation of Flanders’ Interaction Analysis System (CAFIAS). It was revealed that HF teachers spent less time asking questions and more time giving directions than LF teachers. Teachers initiated talk more in the morning, especially on Monday, and students talked more in the afternoon, especially on Friday. Students initiated more talk in the afternoon and were more unpredictable and noncontent oriented in both their initiated and responding behavior in the afternoon. There were no significant interactions between fitness level, day, and time. The current evidence does not support the hypothesis that physically fit teachers are clearly distinguishable from unfit teachers in terms of teacher/student interaction.
Philip E. Martin and Gary D. Heise
Archery instructors believe that force distribution (FD) between the hand and bow grip can have a considerable effect on arrow flight, but there is no empirical support for this speculation. This study examined FD on the bow grip in experienced archers and explored the possible relationships between FD, performance, and fatigue. FD was quantified for 15 experienced archers (8 highly skilled [HS] and 7 less skilled [LS]) using 15 unobtrusive force sensors as each archer completed 72 shots. Arrow position relative to the target center, estimated net moments and moment arms about vertical and horizontal axes through the grip, and shot-to-shot variability in the estimated moments and moment arms were computed for three blocks of six shots. Results demonstrated that (a) estimated moments and moment arms were not consistently related to observed vertical or horizontal deviations in arrow position, (b) there were no systematic differences in FD between HS and LS archers, (c) fatigue had no quantifiable effect on FD, and (d) HS archers displayed less shot-to-shot variability in vertical FD than LS archers, but similar variability horizontally. Results did not support the above-noted common belief of archery instructors.