Biomedical subjects

M S Tremblay

Publications and source records attributed to M S Tremblay.

12 recordsLinked to original sources

PubMed2003

Is the Canadian childhood obesity epidemic related to physical inactivity?

OBJECTIVE: This study examined the relation among children's physical activity, sedentary behaviours, and body mass index (BMI), while controlling for sex, family structure, and socioeconomic status. DESIGN: Epidemiological study examining the relations among physical activity participation, sedentary behaviour (video game use and television (TV)/video watching), and BMI on a nationally representative sample of Canadian children. SUBJECTS: A representative sample of Canadian children aged 7-11 (N=7216) from the 1994 National Longitudinal Survey of Children and Youth was used in the analysis. MEASUREMENTS: Physical activity and sport participation, sedentary behaviour (video game use and TV/video watching), and BMI measured by parental report. RESULTS: Both organized and unorganized sport and physical activity are negatively associated with being overweight (10-24% reduced risk) or obese (23-43% reduced risk), while TV watching and video game use are risk factors for being overweight (17-44% increased risk) or obese (10-61% increased risk). Physical activity and sedentary behaviour partially account for the association of high socioeconomic status and two-parent family structure with the likelihood of being overweight or obese. CONCLUSION: This study provides evidence supporting the link between physical inactivity and obesity of Canadian children.

Age Factors↗

PubMed2002

Temporal trends in overweight and obesity in Canada, 1981-1996.

OBJECTIVE: To assess changes in the prevalence of overweight and obesity among Canadian children and adults between 1981 and 1996 using recent recommendations for the classification of overweight and obesity. DESIGN: Epidemiological study comparing the prevalence of overweight and obesity from the 1981 Canada Fitness Survey (CFS) to the 1996 National Longitudinal Survey of Children and Youth (NLSCY) and the 1996 National Population Health Survey (NPHS). SUBJECTS: Adults 20-64 y of age and children 7-13 y of age from the CFS, NLSCY and NPHS. MEASUREMENTS: BMI was calculated from directly measured or self-reported body mass and height. For adults 20-64 y of age, overweight and obesity were defined as BMI > or = 25 kg/m2 and BMI > or = 30 kg/m2, respectively. Age- and sex-specific cut-off points for children that correspond to the adulthood categories were used to define overweight and obesity for children 7-13 y of age. RESULTS: The prevalence of overweight increased from 48 to 57% among men and from 30 to 35% among women, while the prevalence of obesity increased from 9 to 14% in men and from 8 to 12% in women. The corresponding increases were from 11 to 33% in boys and from 13 to 27% in girls for overweight and from 2 to 10% in boys and from 2 to 9% in girls for obesity. CONCLUSION: The results indicate dramatic increases in the prevalence of both overweight and obesity in Canada over the last 15 y, and the problem is particularly pronounced among children.

Adolescent↗

PubMed2001

Preliminary evaluation of a video questionnaire to assess activity levels of children.

PURPOSE: The purpose of this study was to explore the validity of the Assessment of Young Children's Activity Using Video Technology (ACTIVITY) self-report instrument in assessing previous-day physical activity. METHODS: Forty-seven third-grade children (mean age 7.72 +/- 0.45, 41% female) from one elementary school completed the ACTIVITY on one weekday. To evaluate concurrent validity, children wore a Caltrac accelerometer and a Polar Vantage XL heart rate monitor on the day before completing the ACTIVITY. An ACTIVITY score from six time-anchored questions was obtained from the ACTIVITY. Mean Caltrac counts per minute (CNTSMIN), average activity heart rates, and cumulative minutes at or above 50% of heart rate reserve (50% HRR) were calculated for the entire day (7:00 a.m. to 7:00 p.m.). RESULTS: Significant Pearson product-moment correlations were observed between the ACTIVITY score and CNTSMIN (r = 0.40, P < 0.001) and 50% HRR (r = 0.50, P < 0.001). Answers from four of six time-anchored questions correlated significantly with heart rate scores during those time periods (r = 0.30-0.49). CONCLUSIONS: This exploratory study suggests that the ACTIVITY self-report instrument is a moderately valid instrument for measuring general activity levels of young children during the school year, including during specified periods of time. The potential for video technology to facilitate accurate physical activity recall in young children warrants further study.

Activities of Daily Living↗

PubMed2001

Physical activity assessment options within the context of the Canadian Physical Activity, Fitness, and Lifestyle Appraisal.

The Canadian Physical Activity, Fitness, and Lifestyle Appraisal (CPAFLA) is a standardized battery of tests that is commonly used to assess asymptomatic individuals. This paper reviews evidence concerning the reliability, validity, and utility of the procedure currently used to assess habitual physical activity in the CPAFLA and surveys available physical activity assessment options. Special considerations related to age, gender, ethnicity, seasonal variations, and within-week variance are discussed. The potential assessment options are discussed with consideration given to the logistical and pragmatic constraints inherent in the CPAFLA. New technologies for future assessment of physical activity are briefly presented and recommendations for future research forwarded.

Canada↗

PubMed2001

Hormone responses to resistance vs. endurance exercise in premenopausal females.

Sixteen, cross-trained, premenopausal women participated in an endurance, resistance, and control session to compare hormone responses. The resistance session included 3 sets of eight exercises at 10 RM intensity. The endurance session consisted of a 40-min cycling protocol at 75% of maximal heart rate. During the control session, subjects rested for 35 min. Serum DHEA, estradiol, testosterone, growth hormone, IGF-I, cortisol, and plasma lactate concentrations were measured pre-exercise, post-exercise, and 30 min into recovery. Differences in intensity variables existed between the three sessions. Endurance exercise elicited increases in growth hormone, estradiol, and testosterone compared to the control session, and growth hormone increased after the resistance compared to the control session. The exercise protocols used in this study indicate that an acute bout of exercise can stimulate the endocrine system in premenopausal females. In addition, these results indicate that differences exist between these two exercise protocols when compared to a control session.

Adult↗

PubMed2000

Secular trends in the body mass index of Canadian children.

BACKGROUND: Various changes in society have created the opportunity for more sedentary behaviour and the consumption of food that is high in kilojoules, which may lead to a progressive increase in body mass over time. The purpose of this study was to examine secular changes in the body mass index (BMI) of Canadian children between 1981 and 1996. METHODS: Nationally representative data from the 1981 Canada Fitness Survey, the 1988 Campbell's Survey on the Well-being of Canadians and the 1996 National Longitudinal Survey of Children and Youth were used in the analysis. Regression analyses were used to assess population changes in BMI from 1981 to 1996 for children aged 7-13 years. Changes in the distribution of BMI results were evaluated by plotting the residuals from regression analyses of BMI on age, assessed separately by sex, using the 1981 data as baseline. The proportions of children exceeding the 85th and 95th age- and sex-specific percentiles from the 1981 (baseline) data were also calculated. RESULTS: Since 1981, BMI has increased at the rate of nearly 0.1 kg/m2 per year for both sexes at most ages, indicating a clear secular trend toward an increase in BMI of Canadian children. The prevalence of overweight among boys increased from 15% in 1981 to 28.8% in 1996 and among girls from 15% to 23.6%. The prevalence of obesity in children more than doubled over that period, from 5% to 13.5% for boys and 11.8% for girls. INTERPRETATION: Secular trends indicate that Canadian children aged 7-13 years are becoming progressively overweight and obese.

Adolescent↗

PubMed1996

The effects of acute phosphate supplementation in subjects of different aerobic fitness levels.

Six trained cyclists (high-fitness group) and six untrained individuals (low-fitness group), performed a 20-min cycle ergometer exercise test at 70% of maximum oxygen consumption (VO2max) followed by a 30-min rest period and then an incremental ride to exhaustion on two occasions, 1 week apart. Ninety minutes prior to exercise subjects consumed a drink containing either 22.2 g dibasic calcium phosphate (DCP; treatment) or calcium carbonate (placebo). Blood was drawn prior to drink ingestion, during submaximal exercise, during recovery and at exhaustion for determination of blood 2,3-DPG, blood ATP, plasma lactate, plasma phosphate, haemoglobin and haematocrit. Throughout exercise, cardiorespiratory variables [oxygen uptake (VO2), minute ventilation, (VE), respiratory exchange ratio, heart rate and oxygen pulse] were monitored, and ratings of perceived exertion obtained. Although there was a trend for the low-fitness group to have a higher plasma phosphate concentration prior to treatment ingestion, no treatment effects on plasma phosphate were noted at any sample time in either group. 2,3-DPG, VO2, oxygen pulse, VE, time to exhaustion and VO2max were significantly higher in the high-fitness group; however, no differences in these variables were observed as a result of phosphate ingestion. Plasma lactate was significantly lower in the high-fitness group during the submaximal exercise and the recovery period, but again phosphate ingestion had no effect. These results suggest that acute DCP supplementation is not effective as an ergogenic aid and that aerobic fitness level does not affect the response to phosphate supplementation.

2,3-Diphosphoglycerate↗

PubMed1995

Methodological and statistical considerations for exercise-related hormone evaluations.

Improvements in laboratory techniques have allowed research related to exercise endocrinology to flourish. The emerging literature, however, is often inconsistent and contradictory. The discrepancies in research findings are possibly the result of poor control of confounding variables and/or inappropriate methodologies or analyses. Environmental and pretesting behavioural conditions must be standardised to minimise the influence of variables not directly related to the investigation. Environmental temperature and relative humidity, alcohol, caffeine and nicotine intake, prandial state, sleep deprivation and previous exercise can each alter hormonal responses to exercise. Both prescription and over-the-counter medications can also modify normal hormonal secretions thereby confusing exercise-induced findings. Specimen collection and analysis procedures must be controlled carefully. Changes in plasma volume related to postural changes or tourniquet-induced stasis can confound attempts to isolate exercise-related endocrine responses. The established circadian and rhythmical variations characteristic of many hormones need to be controlled. The specimen selection (plasma, serum, urine, etc), collection, storage and analysis procedures should be carefully planned and evaluated. The magnitude of haemolysis, analytical and biological variation must also be monitored. Isolating the hormonal perturbations resulting from a particular exercise variable can be very difficult. Exercise intensity, duration, mode, frequency and volume may each have specific effects on the endocrine changes seen with exercise and training. Furthermore, hormonal responses to exercise are dependent upon initial training status and fitness level. The statistical procedures and data presentation options selected to convey experimental findings can bias experimental results. The descriptive and inferential statistics to be used for data analysis should be preplanned and consistent with the underlying assumptions of the analytical procedure. Careful consideration should be given to the biological relevance of statistically significant findings. In some cases, data transformations (e.g. absolute vs relative changes, logarithmic) should be considered for analysis or presentation. Given the individual nature of hormonal responses to exercise, emphasis should be placed presenting individual data. Other considerations, including age, sex, racial origin and disease conditions need to be controlled for when trying to examine exercise-induced hormone changes.

Behavior↗

PubMed1994

Ergogenic effects of phosphate loading: physiological fact or methodological fiction?

Inorganic phosphate (Pi) supplementation has been reported to provide ergogenic benefits, though the research findings are inconsistent. Several confounding influences may explain these results, including mode of exercise, exercise intensity, dietary intake, daily biological fluctuations, type of supplement, administered dose of the supplement, washout period, length of loading period, fitness level of subjects, blood volume alterations, and sample collection and analysis techniques. This review provides a critical analysis of the methodological difficulties that may contribute to the equivocal research findings pertaining to Pi supplementation.

2,3-Diphosphoglycerate↗

PubMed1994

Modifications to hydra-gym equipment provide for clinically useful strength measurements.

Modifications were made to the Series III-311 Omnikinetic Hydra-Gym apparatus (Hydra-Fitness Industries Inc., Belton, TX) in an effort to provide relatively inexpensive yet clinically useful isokinetic strength measurements. Signal transmission and processing functions were installed to calculate relevant strength characteristics for knee extension/flexion motions. Results from the modified Hydra-Gym were compared with matched procedures on the Kin-Com (model 500-10, Chattecx Corporation, Chattanooga, TN). Subjects (N = 10) performed three maximal concentric right knee extension/flexion cycles at different resistance settings (2, 4, and 6) on the Hydra-Gym and the corresponding angular velocities on the Kin-Com (190, 125, and 40 degrees/sec, respectively). Each subject completed eight testing sessions, four on each dynamometer. A five-way analysis of variance on the peak torque data revealed no significant difference between dynamometers; however, there was a significant interaction between dynamometer and extension/flexion measurements. The variance in angle of peak torque data was significantly different between dynamometers, with Hydra-Gym showing superior reproducibility (p < 0.005). Mechanical differences between dynamometers produced slightly different, though comparable and consistent, measurement values. Care must be taken when evaluating hamstring/quadriceps ratios from the Hydra-Gym because the interaction noticed between dynamometer and extension/flexion may exaggerate muscle imbalances. In summary, modifications to the Hydra-Gym appear to provide clinicians with a reliable and clinically useful strength testing alternative.

Adolescent↗

PubMed1991

Anabolic steroids in sport.

The use of androgenic-anabolic steroids (AAS) for enhancing athletic performance and body image is widespread. An increasing number of elite and recreational athletes of varying ages and athletic pursuits are using AAS. Sophisticated patterns of AAS use are supported by unethical and illegal distribution channels. Various testosterone-derived preparations attempt to manipulate pharmacological characteristics in an effort to maximize anabolic potential while minimizing androgenic effects. Although anecdotal and theoretical information suggests that AAS have positive ergogenic properties, the experimental evidence is equivocal. In addition to the ethical and legal implications of using AAS, there are diverse, though often reversible, medical and behaviour ramifications. In an effort to control and discourage AAS use, relevant sport governing bodies have implemented various testing and educational programs with undetermined success.

Anabolic Agents↗

PubMed1990

Postoperative exercise training develops normal levels of physical activity in a group of children following cardiac surgery.

Children with congenital heart defects often demonstrate a reduced capacity for exercise, even after surgical intervention. Forty subjects, with various heart defects, completed a 5-year study to evaluate the impact of a postoperative training program on their physical exercise capacity. All of the patients were significantly less active than their peers prior to the surgical intervention. Subjects who completed a simple, home exercise program during the first 3 postoperative months achieved a normal level of physical fitness. These benefits were maintained up to 5-years postoperatively without further intervention. Children who did not receive a postoperative training program remained significantly below their healthy peers. Therefore, a simple exercise training program, conducted early in the postoperative period would appear essential to the achievement of appropriate levels of physical activity for children with congenital heart defects.

Adolescent↗