Search Results

Ethical and logistical limitations preclude the routine determination of anaerobic threshold in children by invasive measurement of blood lactate concentrations or ventilatory parameters. A noninvasive field test developed by Conconi can be used to determine anaerobic threshold through analysis of the heart rate curve during increased exercise workloads. Although this test was initially evaluated in adult athletes, recent data indicate that the Conconi test is applicable to children in both laboratory and field settings. Close correlation with lactate-derived anaerobic threshold appears to be possible when utilizing standard testing protocols.

This study evaluated detection of ventilatory threshold (VT) in adolescents with mental retardation (MR) (17 with MR, 13 with MR and Down Syndrome (DS), mean age 17.5 years). Subjects performed an individualized treadmill VO_2peak test. Two evaluators reviewed the same VT plots 6 weeks apart, using 5 different methods. V_E vs. time elicited the most detectable cases (83%), but significantly fewer youth with DS exhibited a detectable VT using any combination of methods (62% vs. 100%). Only V_E vs. time yielded acceptable detection rate, although this may have been influenced by the protocol used. Intra-evaluator correlation coefficients ranged from 0.91-0.97, and interevaluator reliability coefficients ranged from 0.81-0.93. These findings suggest determination of VT is difficult in this population when using an individualized treadmill protocol, especially in adolescents with DS.

These studies used multilevel modelling to examine optimised peak power (PP_opt) from a force velocity test over the age range 12–14 years. In the first study, body mass, stature, triceps and subscapular skinfold thicknesses of boys and girls, aged 12.3 ± 0.3 y at the onset of the study, were measured on four occasions at 6 monthly intervals. The analysis was founded on 146 PP_opt determinations (79 from boys and 67 from girls). Body mass and stature were significant explanatory variables with sum of two skinfolds exerting an additional effect. No gender differences were evident but PP_opt increased with age. In the second study, thigh muscle volume (TMV) was estimated using magnetic resonance imaging at test occasions two and four. The analysis, founded on a subsample of 67 PP_opt determinations (39 from boys and 28 from girls), demonstrated TMV to be a significant additional explanatory variable alongside body mass and stature with neither age nor gender making a significant contribution to PP_opt. Together the studies demonstrate the influence of body size and TMV on young people’s PP_opt.

The aim of this study was to determine if maximal effort, evidenced by peak HR was attained during the 20m shuttle-run test in a naturalistic setting. Shuttle-run test performance and peak HR were measured in 208 volunteers (11–16 years). Peak HR was 196 (95% confidence interval (C.I.) 194–198 bpm). The relationship between test performance and peak HR was assessed by regression. There was a weak, but statistically significant relationship between test performance and peak HR (R ² = .029, p = .029) but with such a low coefficient of determination (less than 5% criterion), poor performances were not associated with low peak HR values or underestimation of maximal performance. Peak HR values (196 bpm) were higher than cited criterion values (185 bpm) for maximal effort in laboratory studies. In a naturalistic setting, the 20m shuttle-run test elicits a maximal effort in most children.

The objective of this study was to verify the effect of the exercise mode on slow component of VO₂ (VO₂SC) in children aged 11–12 years during severe-intensity exercise. After determination of the lactate threshold (LT) and peak VO₂ (VO₂peak) in both cycling (CE) and running exercise (TR), fourteen active boys completed a series of “square-wave” transitions of 6-min duration at 75%∆ [75%∆ = LT + 0.75 × (VO₂peak—LT)] to determine the VO₂ kinetics. The VO₂SC was significantly higher in CE (180.5 ± 155.8 ml • min⁻¹) than in TR (113.0 ± 84.2 ml · min⁻¹). We can conclude that, although a VO₂SC does indeed develop during TR in children, its magnitude is considerably lower than in CE during severe-intensity exercise.

Based on self-determination theory, the purpose of this study was to explore the mediating role of autonomous motivation in the relation between environmental factors and pedometer-determined PA among 10- to 12-year-old Flemish children. Data were collected from 787 6th grade pupils and one of their parents. Children completed self-report measures including autonomous motivation for PA and perceived autonomy support for PA by parents and friends. Parents completed a questionnaire concerning their PA related parenting practices (logistic support and explicit modeling) and the perceived home environment with respect to PA opportunities. The results confirmed that autonomous motivation mediated the relation between children’s PA and their perceived autonomy support by friends and parents. Autonomous motivation also mediated the relation between parental logistic support and PA. In addition, a positive direct relation was found between parental explicit modeling and children’s PA, and between perceived neighborhood safety and children’s PA.

Little is known regarding the physiological determinants of maximal oxygen uptake (VO₂max) in children. A group of 39 healthy sixth-grade boys (mean age, 12.2 years) underwent maximal cycle testing with determination of cardiovascular factors using Doppler echocardiography as well as standard gas exchange variables. Maximal stroke index was related to VO₂max/kg (r=0.52, p < .05), but no relationship was observed between VO₂max/kg and either maximal heart rate or calculated maximal arteriovenous oxygen difference. Values of maximal stroke index were closely related to those at rest (r = 0.67). These findings suggest that factors influencing resting stroke volume are primarily responsible for inter-individual differences in VO₂max per kg in healthy, non-athletically-trained boys.

Over 60 years ago, Robinson published the first investigation of boys’ aerobic fitness; almost 50 years ago, Åstrand conducted his pioneering studies of both sexes. Twenty four percent of the papers published during the first 10 years of Pediatric Exercise Science (1989-98) involved the determination of peak V̇O₂. Yet, the interpretation of aerobic fitness during childhood and adolescence is still shrouded with controversy. In this paper we review peak V̇O₂ in relation to age, growth, maturation, and sex. We describe the increase in peak V̇O₂ with age, challenge the traditional interpretation of peak V̇O₂ during growth, demonstrate the independent contribution of maturation to peak V̇O₂, and address the progressive divergence of boys’ and girls’ peak V̇O₂, during childhood and adolescence.

This study was done to determine the extent to which body composition accounts for differences in anaerobic characteristics between 12-year-old girls and boys. Peak leg power (PP), mean leg power (MP), percent body fat, fat free mass (FFM), and lean thigh volume (LTV) were determined by various tests. Pubertal stages and salivary testosterone concentration (in boys) were used to assess sexual maturation. Laboratory anaerobic indices were compared with performances in two running tests. Blood samples were taken for lactate determination. Absolute PP and MP outputs were similar in both sexes and were better correlated with LTV in girls, whereas in boys both PP and MP were highly correlated with FFM. Although nonsignificant gender difference in lean tissue was observed, PP and MP when corrected for LTV were significantly greater in boys than in girls. Factors other than the amount of lean muscle mass should be considered in explaining the gender differences in PP and MP in early pubertal children.

This paper analyzes the determination of the criterion referenced standards for the neuromuscular physical fitness items (sit-ups, sit-and-reach, and pullups) typically included in health related physical fitness test batteries for children and adolescents. Criterion referenced standards should be linked to some specific status on a health criterion that represents an absolute desirable level of that characteristic. Three techniques used to determine and/or validate criterion referenced standards are discussed: the use of empirical data with an established criterion test, the use of empirical data with instructed versus uninstructed groups, and the use of normative data and expert judgment. It is concluded that the existing criterion referenced standards have been derived exclusively from normative data and expert opinion. It remains unknown as to the meaning of these standards in relation to desirable and absolute levels of health.