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  • Author: Oded Bar-Or x
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Oded Bar-Or

This review is intended to critically examine the notion that physical training, in addition to its nonspecific effects on fitness, can induce disease-specific benefits in the child with a chronic disease. Conditions included in this analysis are asthma, cerebral palsy, coronary risk, cystic fibrosis, diabetes mellitus, hypertension, myopathies, and obesity. Most of the published intervention studies are deficient in design by not including randomly assigned (or matched) controls. Other constraints stem from the need to simultaneously maintain other therapeutic modalities, the progressive nature of some of the diseases, and the small pool of suitable subjects.

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Edited by Oded Bar-Or

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Oded Bar-Or and Boguslaw Wilk

This article reviews studies, mostly from the authors' laboratory, on children's sweating rates and composition, voluntary drinking patterns during prolonged exercise in the heat, taste perception of beverages, and the importance of fluid flavor and composition in preventing voluntary dehydration. Subjects were children, exposed for 90 to 180 min to intermittent bouts of cycling (45-50% maximal O2 uptake) in a climatic chamber (mostly at 35 C°, 40-50% relative humidity). There were five main findings: When given unflavored water ad libitum, children dehydrated progressively and their core temperature increased faster than in adults. When offered drinks with various flavors, children preferred grape to other flavors. When given grape-flavored water during intermittent exercise in the heat, children voluntarily drank 44.5% more than with unflavored water. When given grape-flavored carbohydrate-electrolyte solution, they voluntarily drank 91% more than with unflavored water. Finally, such consumption of carbohydrate-electrolyte solution was sufficient to prevent voluntary dehydration during 180-min intermittent exercise in the heat.

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Bareket Falk and Oded Bar-Or

A mixed cross-sectional longitudinal design was used to study the effect of growth and physical maturation on peak aerobic and anaerobic mechanical power. Subjects were divided into three groups based on Tanner staging: 16 prepubertal (PP, Stage 1), 15 midpubertal (MP, Stages 2, 3, 4), and 5 late pubertal (LP, Stage 5). Aerobic and anaerobic power were observed every 6 months for IS months. Peak mechanical aerobic power and peak oxygen consumption were determined using a progressive cycle ergometer test. Anaerobic power indices were derived from the Wingate Anaerobic Test. There was no difference in peak mechanical aerobic power (in W · kg−1) among the maturation groups, nor with chronological age. There was a significant difference in peak and mean anaerobic power (in W · kg−1) among maturation groups, but the increase with chronological age was not statistically significant. There was a significant correlation between aerobic and anaerobic power (in Watt) during each session among the PP and MP boys but not among the LP boys. This may suggest that the child’s metabolic specialization into either an aerobic or anaerobic performer begins in late puberty.

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Oded Bar-Or and Tom Baranowski

This review examines the evidence that the level of physical activity (PA) or total energy expenditure during adolescence affects body adiposity in the obese and nonobese adolescent population. Several cross-sectional studies suggested that obese children were less physically active than their nonobese peers, but there was no consistent difference in the total energy expenditure. The likelihood that infants of obese mothers become obese at age 1 year is greater if their total energy expenditure (using the doubly labeled water technique) is lower at age 3 months. Many interventional studies in the general adolescent population show a small (1-3% body fat) reduction in adiposity as a result of physical training. It appears, though, that programs longer than one year are more efficacious than shorter programs. Lifestyle activities (e.g., walking to and from school) appear to have a more lasting effect than regimented activities (e.g., calisthenics or jogging).

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Patricia E. Longmuir and Oded Bar-Or

This study examined gender, disability type, age, and specific diagnostic category in relation to habitual physical activity levels (HPA), perceived fitness (PF), and perceived participation limitations (PPL) of youths, ages 6 to 20 years, in Ontario, Canada. Data collected through a mailed survey (Longmuir & Bar-Or, 1994) were reanalyzed using ANOVA and chi square statistics to provide new information. The 458 girls and 499 boys were classified by disability type: physical, chronic medical, visual, and hearing. Significant differences (p < .01) were between (a) HPA and disability type, specific diagnostic category, and age; (b) PF and disability type; and (c) PPL and disability type. Gender did not influence the results. Youths with cerebral palsy, muscular dystrophy, and visual impairment had the most sedentary lifestyles.

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Flavia Meyer, Oded Bar-Or and Boguslaw Wilk

Twelve 9- to 12-year-old children performed four exercise-in-the-heat trials (35 C°, 45% RH), which differed in the fluids consumed. In each trial, subjects were kept euhydrated while cycling one 20-min and two 15-min bouts at 50% peak VO2 followed by a 90% peak VO2 bout until exhaustion. Thereafter, they could drink ab libitum while resting. One drink was water, and the other three drinks had 6% CHO with different Na+: 0, 8.8, and 18.5 mEq · L1. All drinks had the same grape flavor. The perceived thirst was similar among trials and it did not increase while subjects were exercising. On average, subjects felt their stomach “somewhat full” with no difference among drinks. Thermal sensations, RPE, and overall comfort were similar among trials. During a 30-min recovery, volume intake was similar among drinks (201 ± 27 ml). In conclusion, the drink composition did not affect perceptual responses to drinking while euhydrated children exercised in the heat, nor did it affect drinking behavior during recovery.

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Martine Hoofwijk, Viswanath Unnithan and Oded Bar-Or

Nine children with spastic cerebral palsy (CP) and 9 controls (mean age 13.5 and 14.0, respectively) completed a maximal walking test on the treadmill. Initial gradient was set at 0% with a speed increase every 2 minutes until the “fastest walking speed” was achieved in the third stage. The gradient was then increased by 2.5–5% every 2 minutes. V̇O2max of the CP children was significantly lower (p = .001) than that of the controls (32.7 vs. 45.2 ml · kg1 · min−1). There was no significant difference in maximal heart rate between the two groups (189 vs. 197). However, the CP subjects had significantly higher (p = .007) ventilatory equivalent for O2 compared to the controls (41.4 vs. 33.6). The lower V̇O2max values of the CP children might reflect inefficient ventilation, compromised circulation, and local fatigue in the spastic limb muscles.

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Désirée Maltais, Izumi Kondo and Oded Bar-Or

To determine optimal arm crank speed for subjects with cerebral palsy (CP), and whether it differs at high or low power output (PO), the cardiopulmonary cost and economy of cranking at 20, 30, and 40 rpm under a low (0.09 W · cm−1 arm span) and a high (0.12 or 0.18 W · cm−1 arm span) PO were measured in 11 adolescents (14.3 ± 2.4 years) with spastic diplegic CP. Data were analyzed using an ANOVA for repeated measures and post hoc (for between-speed differences) using Tukey’s test for honestly significant differences. Crank speed did not affect the cardiopulmonary cost nor economy at low PO. Under high PO, net economy at 30 rpm (12.2%) was significantly (p = .001) higher than at 20 rpm (10.2%), with a trend (p = .055) to also be higher than at 40 rpm (11.1%). Gross economy showed a similar pattern. These results suggest that cranking at 30 rpm under high PO may be more economical than cranking at 20 or 40 rpm.

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Patricia E. Longmuir and Oded Bar-Or

To date, very little published information has been available on the physical activity participation of disabled youth. A questionnaire, which was modified from the Canada Fitness Survey, was distributed by mail to physically disabled, sensory impaired, and chronically ill children and adolescents in Ontario, Canada. Nine hundred eighty-seven responses were collected from subjects 6 to 20 years of age, with a response rate of 58%. Twenty-nine percent of physically challenged youth were found to be sedentary, and 39% were active. Activity levels were significantly related to age (p < .01), with a marked decline in the second decade of life. Activity levels were not significantly influenced by gender, but the data suggest that girls have lower activity levels and a faster and earlier decline in activity than boys. Overall, the data collected provide baseline information on the role of physical activity in the lives of Ontario youth with physical disabilities, sensory impairments, and chronic illnesses.