Christina A. Geithner

Growth in peak aerobic power during adolescence.

PURPOSE To model the growth of peak aerobic power during adolescence in both sexes followed longitudinally from 10 to 18 yr. METHODS Peak aerobic power (peak VO2) was measured annually during a maximal treadmill test with the Bruce protocol. Height and weight were measured semiannually. The Preece-Baines Model I growth function was used to fit curves to data for individuals with >/= six observations for peak aerobic power to estimate age at peak velocity (PV) for peak VO2 (age at PVPVO2), PVPVO2 (L x min(-1) x yr(-1)), and value at PVPVO2 (L x min(-1)) for each individual. Curves were successfully fitted for 83 individuals (48 males, 35 females). The model was also fitted to individual data for height and weight to estimate ages at peak height velocity (PHV) and peak weight velocity (PWV). Age at PVPVO2 was compared with ages at PHV and PWV. Pearson correlation coefficients were calculated between ages at PV and PV for peak VO2, height, and weight. RESULTS Mean ages at PVPVO2 are 12.3 +/- 1.2 yr for females and 14.1 +/- 1.2 yr for males. Peak VO2 increases in both sexes throughout adolescence, with males having higher values than females at all ages. Age at PVPVO2 occurs nearly coincident with PHV and before PWV in both sexes. Correlation coefficients among ages at PHV, PWV, and PVPVO2 suggest a general maturity factor for body size and aerobic power. CONCLUSION Growth in peak VO2 exhibits a clear growth spurt in both sexes during adolescence. The growth spurt occurs earlier in females but is of greater magnitude in males.

Body Composition of Young Athletes

Absolute and relative components of body mass are a primary focus in studies of body composition. Components change with growth and maturation, requiring care in selecting methods of assessment in children and adolescents. Although sex differences are apparent in fat-free mass (FFM), fat mass (FM), and relative fatness (% Fat) during childhood, they are more clearly defined during adolescence and adulthood. Body composition is one of many determinants of sport performance, but % Fat tends to be the primary focus of discussion in young athletes. The influence of training for sport on bone mineral has received more attention in recent years because of methodological advances in assessment and concern for potential negative effects of altered menstrual function on bone. Relative fatness of young athletes in several sports is summarized, and issues related to sport training and body composition in young athletes are considered. Suggestions for dealing with body composition in young athletes are provided.

The adolescent spurt and sexual maturation in girls active and not active in sport

Girls actively training in sport (n=23) and girls not active in sport (n=26) were compared in terms of ages at peak height velocity (PHV) and menarche, the interval between ages at PHV and menarche, and ages at attaining stages of pubic hair and breast and the estimated duration of the stages. Subjects were longitudinally followed from about 11-18 years of age. Stature and weight were measured and stages of pubic hair and breast development were rated at approximately quarterly intervals between the initial observation and 14 years of age, at semiannual intervals until 16 years, and at irregular intervals subsequently. Age at menarche was obtained prospectively. The active girls trained 12 hours per week in rowing, track and swimming for an average of 3.9+/-1.2 years during puberty and the growth spurt. Longitudinal stature records for individual girls were fitted with kernel regression to estimate age at PHV (years). The interval between age at PHV and age at menarche was calculated. Ages at appearance of pubic hair and breast stages 3, 4 and 5 were calculated by back-interpolation, while intervals between stages 3 and 4 were calculated after log 10 transformation. Peak height velocity and menarche occur, on average, slightly later in girls active in sport, but the differences are not significant. The interval between PHV and menarche, PHV (cm/year), ages at attaining pubic hair and breast stages 3, 4 and 5, and estimated intervals between adjacent stages also do not significantly differ between girls actively training in sport and those not active in sport. Thus, regular training in sport during puberty and the adolescent spurt does not apparently influence the timing and progression of somatic and sexual maturation in girls.

Adolescent spurts in body dimensions: Average and modal sequences

The sequence of growth spurts in 11 body dimensions was examined in 101 Polish adolescents, 52 males and 49 females, followed longitudinally from 11–18 years. The dimensions included weight; stature; symphyseal height; biacromial and bicristal breadths; and arm, forearm, chest, thigh and calf circumferences. Upper segment length was estimated as stature minus symphyseal height. Measurements were taken quarterly from 11–14 years, and annually or less frequently thereafter. Growth curves were fitted to individual longitudinal observations using kernel regression to derive estimates of ages at peak velocity (PV) and peak velocities. Within each sex, mean ages at PV were used to define the average sequence, while the most frequently observed sequence of PVs in individuals was used to define the modal sequence. Average and modal sequences differed, the latter probably reflecting individual variability in timing. The spurt in the estimate of leg length (symphyseal height) occurred prior to that for stature in males (first in the sequence) and was nearly coincident with that for stature in females (second in the sequence by 0.01 years). The timing of spurts in other dimensions within each sex was more variable in both average and modal sequences. Am. J. Hum. Biol. 11:287–295, 1999.

THE RELATIVE AGE EFFECT IN WOMEN’S ICE HOCKEY: INTERNATIONAL AND POSITIONAL COMPARISONS

A relative age effect (RAE), or chronological age differences among individuals within the same age group, has been observed in 14 sports (Cobley et al., 2009). A strong RAE has been reported in me ...

Constructing engaged learning in Scientific Writing

Purpose – The purpose of this paper is to incorporate a blended pedagogical approach to Scientific Writing, and assess its effectiveness in improving students’ writing skills and scientific literacy. Effective writing is vital to the dissemination of scientific information and a critical skill for undergraduate science students. Various pedagogical strategies have been successful in improving writing skills and developing scientific literacy. Design/methodology/approach – Mean scores on draft and revision assignments were examined longitudinally (2013 cohort, n=51) and across cohorts (2011, 2012, and 2013; combined n=94). Domain-specific composite scores were calculated from survey items addressing students’ self-perceptions of knowledge (K), general and scientific writing skills (GWS and SWS), and attitudes (A) related to scientific literacy. Changes in composite scores were analyzed using paired t-tests, and cross-cohort differences were examined via MANOVAs (SPSS, p < 0.05). Findings – Mean scores on r...

The Relative Age Effect in Women's Ice Hockey : International and Positional Comparison

A relative age effect (RAE), or chronological age differences among individuals within the same age group, has been observed in 14 sports (Cobley et al., 2009). A strong RAE has been reported in me ...

Physical And Performance Differences Among Forwards, Defensemen, And Goalies In Elite Women??s Ice Hockey: 2447 Board #3

Positional differences have been examined in womens basketball, field hockey, netball, and volleyball, but not in elite womens ice hockey. Our purpose was to describe and compare physical, fitness, and skating performance characteristics of forwards (F), defensemen (D), and goalies (G). Subjects were 112 University of Alberta women players (21.4 ± 2.9 years of age). A full anthropometric battery was conducted on each player. Heath-Carter anthropometric somatotypes were calculated. Percent body fat (%fat) was estimated from both general and population-specific equations. Subjects performed off-ice fitness tests (vertical jump, 40-yd dash, Leger test for predicting &OV0312;O2max) and on-ice fitness (Modified 3-Repeat Sprint Skate Test—MRSS, blood lactate after sprint test) and skating performance tests (6.10-m acceleration test, Cornering S-Turn Agility Test). Descriptive statistics and multivariate analyses of variance were run using SPSS (Version 10.0) for the MacIntosh, with a significance level set a priori at p> 0.05. Significant positional differences were found for bicristal breadths (D > G, F > G); relaxed arm circumference (D > F, G > F); supraspinale and biceps skinfolds (G > D, G > F); and endomorphy (G > F). Significant differences among positions were also found for the MRSS (G > D > F) and agility tests (G > D, G > F). D tended to have the most robust build overall. F were leaner than D and G, and their smaller relaxed arm circumference measurements most likely reflect less subcutaneous fat on the upper arm. F had greater anaerobic power than D, followed by G, and they tended to have greater aerobic capacity. F and D were more agile than G. Performance demands appear to be position specific. F need to be the most versatile and fit because of a greater amount and variety of work performed both during practices and games; their required degrees of versatility and fitness are followed by those required of D and G.