Fitness centre membership is related to healthy behaviours.

AIM: Maximizing the health benefits associated with reducing inactivity levels requires an understanding of the individual and environmental determinants of physical activity. Membership in a fitness facility promotes physical activity, yet little is known of its relationship to health. The purpose of this study was to compare physical activity levels, and health status, behaviours, and beliefs, in members of a fitness centre, and non-member community residents. METHODS: Using a cross-sectional design, fitness centre members (n=236) and non-members (n=302) were compared with respect to perceived health status, use of health care services, fitness status, physical activity level, perceived control over health, and the likelihood of engaging in health promoting behaviours, using The Health-Promoting Lifestyle Profile. Questionnaires were mailed to adult members of a fitness centre, and a stratified (age, sex) sample of non-members randomly selected from the local community. RESULTS: Fitness centre members were more likely than the comparison group to have visited a general physician, dentist, athletic therapist, optometrist, or nutritionist during the previous year (p<0.05), to exercise regularly, and to rate their physical fitness as very fit. They scored significantly higher on the overall health promoting lifestyle score (p=0.0353) as well as on health responsibility (p=0.0053), exercise (p=0.0001), and nutrition (p=0.0166) subscales, even after adjusting for differences in activity levels between groups. CONCLUSIONS: Fitness centre membership is associated with increased health responsibility and health promoting behaviours. This finding appears to be related to membership in the fitness centre, and not to increased participation in physical activity.

Effectiveness of three field treatments for induced mild (33.0 degrees C) hypothermia.

Three field applicable treatments for hypothermia were compared. Subjects were cooled in stirred cold water (8.0 degrees C) to a core temperature (Tco) as low as 33 degrees C and rewarmed in a random order by each of three techniques: shivering, external heat, and treadmill exercise. Tco was monitored with an esophageal thermistor probe at the level of the heart. Treatment effectiveness was determined by calculating the amount of Tco afterdrop, length of afterdrop period, rate of Tco increase, and total recovery time. Rate of Tco increase for exercise (4.9 degrees C/h) was significantly higher (P less than 0.05) than shivering (3.5 degrees C/h) but not external heat (3.7 degrees C/h). Exercise afterdrop amount and afterdrop length values (0.95 degrees C and 24 min, respectively) were significantly higher (P less than 0.05) than both shivering (0.33 degrees C, 15 min) and external heat (0.32 degrees C, 14 min). Therefore, although rate of Tco increase during recovery for exercise was faster than for shivering or external heat, as it was preceded by a greater afterdrop length and amount, total recovery time did not differ among the three treatments.

Alterations in anaerobic threshold as the result of endurance training and detraining.

The response of anaerobic threshold (AT) to endurance training and detraining was studied in 21 males (mean age = 25 yr). Members of the exercise group trained on a cycle ergometer at 80% of maximal oxygen uptake (VO2max) for 30 min four times per week for 9 wk. Nine weeks of detraining followed. A step-wise incremented cycle ergometer test was used to measure maximal and submaximal values of metabolic variables at 3-wk intervals. The criterion for determination of the onset of metabolic acidosis was a systematic increase in the ventilatory equivalent for O2 (VE/VO2) without an increase in the ventilatory equivalent for CO2 (VE/VCO2). Significant increases and decreases of VO2max for the exercise group during training and detraining, respectively, were revealed by ANOVA. Following 9 wk of training, elevations of 70.4% and 19.4% had occurred in AT expressed as absolute VO2 (AT l . min-1) and percent of VO2max (AT-VO2), respectively. The latter change was not statistically significant. Losses of training gains in AT (l . min-1) were significant after 6 and 9 wk of detraining. The results of this study indicate that 9 wk of training is of sufficient duration to cause a significant alteration in AT. Loss of this training gain occurs rapidly and appears to be similar to changes in VO2max.

Influence of walking volume on health benefits in women post-menopause.

The health benefits of physical activity are believed to be related more to exercise volume than to intensity. In this 24-wk study, we examined the effect of walking volume on aerobic fitness, serum lipids, and body composition in women post-menopause, a population at risk for coronary artery disease. Of 79 women randomly assigned to groups at the outset, 56 completed the study (mean age 61.3 +/- 5.8). Participants walked at an intensity of 60% peak oxygen uptake (VO2peak) for 60 min, 3 d.wk-1 (N = 19) or 5 d.wk-1 (N = 17), or remained sedentary (N = 20). Walking 3 or 5 d.wk-1 increased VO2peak (ml.kg-1.min-1) by 12% and 14%, respectively (P < 0.01). There were no changes in serum lipids in response to either program. Percent body fat decreased by 1.1% and 1.3% in those walking 3 and 5 d.wk-1, respectively; both changes significantly different from the control group (P < 0.05). Walking 5 d.wk-1 did not result in more health benefits than 3 d.wk-1, possibly due to a greater compensatory decline in activities other than the walking program, or greater discrepancies between actual and reported activity and food intake. Longer-duration programs, or simultaneous changes in diet, may be necessary to alter serum lipids in nonobese, normo-lipidemic women post-menopause.

The interactive effects of Type A behavior and hostility on bleeding time thromboxane and prostacyclin formation.

Sixty-six male university students were classified as Type A or B on the basis of the Structured Interview of Rosenman and as hostile or non-hostile on the basis of the Cook-Medley scale. Vascular production of prostacyclin and platelet thromboxane in response to a standard vessel injury was evaluated. Basal thromboxane production, measured as the primary metabolite, thromboxane B2, in blood oozing from the bleeding-time site, was highest among hostile Type A subjects with significantly lower thromboxane production in hostile Type Bs and all non-hostile groups combined. Following an exercise treadmill test hostile subjects produced more thromboxane than non-hostile ones, and hostile Type As had significantly shorter bleeding times than hostile Type Bs. No significant differences on any measure were observed following a stressful color naming task. The observed interaction of hostility and Type A behavior on bleeding time thromboxane formation links behavior to an adverse aspect of a thrombosis-related parameter thought to be involved in the genesis of cardiovascular disease.

Walking program reduces elevated cholesterol in women postmenopause.

OBJECTIVE: To examine the effect of a moderate exercise regimen on total serum cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), body composition and cardiovascular fitness (VO2 max) in mildly hyperlipidemic women, postmenopause. DESIGN: Randomized assignment to walking (n = 24) or control (n = 16) groups. SETTING: Community based intervention. PARTICIPANTS: Over 300 volunteers were screened to obtain the sample of 40 eligible women. Participants were mildly hyperlipidemic, postmenopause (mean age 62.0 +/- 5.7 years), sedentary, nonsmokers and not on hormone replacement therapy. Results are reported for the 25 subjects (15 walkers, 10 controls) who completed the study. INTERVENTION: Exercisers walked an average of 54.3 +/- 7.7 mins/day, 4.9 +/- 1.7 days/week, at an intensity of 54% maximum heart rate reserve, for six months. Participants were counselled not to change their diets. MAIN RESULTS: Total serum cholesterol, triglyceride, total serum cholesterol: HDL-C ratio, weight and fat mass decreased significantly in the walkers compared with the controls (P < 0.05), as did body mass index (P < 0.01). Walking resulted in a significant increase in VO2 max (P < 0.01). Changes in serum lipids were significantly related to changes in body fat, but not to change in aerobic fitness. There were no changes in dietary intake. CONCLUSIONS: A moderate intensity exercise program induces favourable alterations in total serum cholesterol and other atherogenic indices in hyperlipidemic women postmenopause, and these changes are related more to loss of body fat than to increased fitness level.

Serum ferritin and heart disease: the effect of moderate exercise on stored iron levels in postmenopausal women.

OBJECTIVE: To determine the effect of a moderate exercise regimen on stored iron as measured by serum ferritin in previously sedentary postmenopausal women. DESIGN: Randomized assignment to one of three groups: a five day/week walking group (five-day group, n = 27); a three day/week walking group (three-day group, n = 27) or a sedentary group (control group, n = 25). SETTING: Community-based intervention. PARTICIPANTS: Women who were postmenopausal, over 50 years old, sedentary, not on hormone replacement therapy, nonsmokers, physically capable of exercising, without clinical signs of cardiovascular, pulmonary or metabolic disease, and not on medication that would affect iron metabolism. In addition, they had neither donated blood nor been transfused within the previous 12 months. All participants were screened volunteers who had responded to media advertisements. Seventy-nine participants met these criteria. Results are reported for 56 subjects (five-day group, n = 17; three-day group, n = 19; control group, n = 20) who completed the study. Their mean age was 61.3 +/- 5.8 years. INTERVENTION: The five-day group and the three-day group walked an average of 279 +/- 20 and 171 +/- 7 mins/week, respectively. Participants were counselled not to change their dietary intake. MAIN RESULTS: Following 24 weeks of walking, mean serum ferritin decreased significantly in the five-day group (P < 0.03), but not in the three-day group (P < 0.09) compared with controls. CONCLUSIONS: The extent of physical activity required to elicit a decrease in stored iron in postmenopausal women was determined. This may be clinically significant because stored iron increases significantly following menopause and excess stored iron have been cited as risk factors for coronary artery disease.

Survey of exercise and dietary knowledge and behaviour in persons with type II diabetes.

A survey was conducted to assess the potential for an exercise and weight control program for persons with Type II diabetes. Questionnaires were sent to 1,000 individuals with diabetes, who were randomly selected from the provincial health records office. Physicians and dietitians were the primary sources of information about both exercise and diet. Although few respondents participated in organized (7.7%) or informal (36.8%) exercise programs, or expressed an interest in participating (36.8%), the majority (84.0%) believed that they should get more exercise. This points to a gap between attitude and behaviour. Activity preferences were similar to those reported previously for all Canadians, however, barriers to participation differed in the present group. It was concluded that barriers must be assessed, and behaviour modification included, if diet and exercise programs are to be successful in this population.

Walking program maintenance in women with elevated serum cholesterol.

Health benefits are commonly reported in supervised exercise studies but it is not known whether participants remain active upon completion of the program. The walking habits of 21 older women (M = 62.0 +/- 4.8 years) with moderately elevated serum cholesterol were monitored for 12 months following completion of a supervised walking program. The average amount they walked per week decreased significantly--from approximately 4.5 hours to less than 3 hours after 3 and 6 months. After 12 months, one third of the participants continued to walk for more than 4 hours per week, 50% walked from 2 to 4 hours per week, and 20% had quit walking. Walking maintenance was not significantly associated with fitness level, percentage of body fat, or change in weight during the supervised program. Those who achieved the greatest reduction in serum cholesterol, however, were more likely to maintain walking levels after 12 months. Perceived lack of control over their physical activity levels by older women and loss of socialization and feedback may explain the decrease in activity observed after completion of a supervised program.

Aerobic fitness level (VO2max) moderates the increased cardiovascular function and basal thromboxane formation of young healthy Type A males.

The authors evaluated the interaction between physical fitness and Type A behavior on vascular production of prostacyclin and platelet thromboxane in response to a standard vessel injury. Ninety-seven male university students were classified as Type A or B on the basis of the Structured Interview of Rosenman. Reactivity, as measured by changes in systolic blood pressure (SBP), and heart rate (HR), measured before and after a stressful Stroop task 1 week later, showed that Type A individuals were more reactive to the stressor than Type Bs, providing independent confirmation of the behavioral interview assessment procedure. Fitness level was determined by a graded treadmill test and was not different for Type As and Type Bs. Basal thromboxane production, measured as the primary metabolite, thromboxane B2, in blood oozing from the bleeding-time site, was highest among unfit Type A subjects. Fit Type As and Type Bs showed significantly lower thromboxane production. No significant differences in prostacyclin production were seen. This study marks the first time that behavior pattern has been linked to an adverse aspect of a thrombosis-related parameter likely to be involved in the genesis of cardiovascular disease. The present results also indicate that physical fitness may, in some fashion, ameliorate the "toxic" effects of Type A behavior.

The response of obese females to low impact exercise and diet counselling.

Obese women enrolled in a 24 week low impact exercise program were assigned to either an exercise or an exercise plus diet counselling treatment. Overweight volunteers were recruited to serve as the control group. No significant changes were observed in maximal oxygen uptake, serum lipids, body composition, self esteem or physical body image during the program. A significant negative correlation was found between changes in serum HDL-C and changes in percent body fat. Maximal oxygen uptake was significantly and positively related to self esteem and physical body image. Participants who received diet counselling were less likely to drop out of the program than other members of the exercise group, and were more likely to attend classes. Changes in dietary intake were similar in all exercising subjects, regardless of counselling. These results suggest that a short term program of low impact exercise may not be sufficient to produce significant adaptations in this population.

Hypercapnia lowers the shivering threshold and increases core cooling rate in humans.

BACKGROUND: Hypercapnia, which may be encountered during diving operations or by patients under general anesthesia with spontaneous respiration, alters the basic thermoregulatory responses of animals and humans. In cold-exposed animals, 3-10% inspired CO2 impairs thermal homeostasis by attenuating shivering and promoting heat loss through peripheral vasodilation. Experimental results with humans are equivocal. PURPOSE: To determine the effects of hypercapnia on warm and cold thermoregulatory responses and core cooling rates during mild cold stress, we examined the core temperature (TCO) thresholds for sweating, vasoconstriction and shivering, as well as core cooling rates of eight subjects immersed in 28 degrees C water under hypercapnic conditions. METHODS: On two separate days, subjects exercised on an underwater cycle ergometer to elevate TCO above the sweating threshold. They then rested and cooled until they shivered vigorously. Subjects inspired humidified room air during the control trial and 4% CO2/20.9% O2/balance N2 during the hypercapnia trial. RESULTS: Hypercapnia lowered the threshold for shivering by 0.13 degrees C and increased the core cooling rate by 0.35 degrees C.h-1 (25%). Minute ventilation was approximately 12.0 L.min-1 throughout cooling during control and increased from 25.3 to 28.7 L.min-1 during hypercapnia. CONCLUSIONS: Therefore, hypercapnia enhances the core cooling rate during mild cold stress. This may be attributed in part to a delay in shivering onset, as well as increased respiratory heat loss during hypercapnic hyperventilation.

The physiological response of siberian husky dogs to exercise: effect of interval training.

Five Siberian Husky Dogs participated in an initial study to determine their physiological response to three types of exercise. Blood samples were taken prior to, and three minutes following, a 7.5 km free run and 6 km team sled run for the determination of hemoglobin, hematocrit, red and white blood cell counts, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, lactate dehydrogenase, creatine phosphokinase and serum glutamic pyruvic transaminase. Samples were also taken following a 90s sprint run. Heart rate was taken immediately after each run by palpation of the femoral pulse. Average heart rates following the 90s, 7.5 km and 6 km runs were 190 bpm, 211 bpm and 166 bpm, respectively. Mean lactate concentrations following the 90s, 7.5 km and 6 km runs were 1.74 mMol . 1(-1), 0.70 mMol . 1(-1), and 3.06 mMol . 1(-1), respectively. Elevation of lactate dehydrogenase and creatine phosphokinase was greatest following the 6 km sled run. Three of the above dogs were then studied before and after a 12 week interval training program, while three other dogs served as controls. The animals completed a three stage, submaximal treadmill test prior to and following the program. Pre and post blood samples were taken, and rectal temperature and heart rate were recorded continuously throughout the test. An analysis of variance was used to examine the significance of differences between and within groups. Although the response of heart rate, lactate, temperature and serum enzymes to submaximal exercise did not change with training significant differences between groups suggested that a more prolonged program may have resulted in such adaptations.

Improved estimation of the health and economic burden of chronic disease risk factors in Manitoba.

INTRODUCTION: There are analytic challenges involved with estimating the aggregate burden of multiple risk factors (RFs) in a population. We describe a methodology to account for overlapping RFs in some sub-populations, a phenomenon that leads to "double-counting" the diseases and economic burden generated by those factors. METHODS: Our method uses an efficient approach to accurately analyze the aggregate economic burden of chronic disease across a multifactorial system. In addition, it involves considering the effect of body weight as a continuous or polytomous exposure that ranges from no excess weight through overweight to obesity. We then apply this method to smoking, physical inactivity and overweight/obesity in Manitoba, a province of Canada. RESULTS: The annual aggregate economic burden of the RFs in Manitoba in 2008 is about $1.6 billion ($557 million for smoking, $299 million for physical inactivity and $747 million for overweight/obesity). The total burden represents a 12.6% downward adjustment to account for the effect of multiple RFs in some individuals in the population. CONCLUSION: An improved estimate of the aggregate economic burden of multiple RFs in a given population can assist in prioritizing and gaining support for primary prevention initiatives.

TITRE: Meilleure estimation du fardeau que représentent les facteurs de risque de maladie chronique pour la santé et l'économie au Manitoba. INTRODUCTION: L'estimation du fardeau global que représentent les facteurs de risque multiples au sein d'une population présente certains défis d'ordre analytique. Nous décrivons une méthodologie permettant de tenir compte des facteurs de risque se chevauchant dans certaines sous-populations et entraînant un « double compte ¼ des maladies et du fardeau économique qu'ils engendrent. MÉTHODOLOGIE: Notre démarche permet d'analyser avec précision le fardeau économique global des maladies chroniques dans un cadre multifactoriel tout en tenant compte de l'incidence du poids en tant qu'exposition continue ou polytomique (allant de l'absence d'excédent de poids au surpoids et à l'obésité). Nous appliquons cette méthode au tabagisme, à l'inactivité physique et au surpoids et à l'obésité à la province du Manitoba (Canada). RÉSULTATS: En 2008, le fardeau économique global annuel des facteurs de risque au Manitoba était d'environ 1,6 milliard de dollars (557 millions pour le tabagisme, 299 millions pour l'inactivité physique et 747 millions pour le surpoids et l'obésité). Le fardeau total représente un rajustement à la baisse de 12,6 % lorsqu'on tient compte de l'effet des facteurs de risque multiples chez certaines personnes. CONCLUSION: Une meilleure estimation du fardeau économique global des facteurs de risque multiples au sein d'une population peut faciliter l'établissement des priorités et améliorer le soutien aux initiatives de prévention primaire.

Physiological characteristics of male and female middle distance runners.

The purpose of this investigation was to obtain physiological profiles of highly ranked middle distance runners in the province. Seven male (x age = 23.4 yr) and 5 female (x age = 18.6 yr) athletes were evaluated on selected measures related to performance. Average height, weight, and body fat were 176.7 cm, 67.0 kg, 7.8% and 166.7 cm, 51.6 kg and 14.9% for the males and females, respectively. Maximal oxygen uptake average 5.09 l X min-1, or 76.0 ml X kg-1 X min-1, for the males, and 3.59 l X min-1, or 68.0 ml X kg-1 X min-1, for the females. The difference was significant (p greater than 0.05) between the sexes for all of the above variables except maximal aerobic power expressed relative to body weight. Little sex related difference existed in peak torque or power, expressed relative to body weight, generated during flexion and extension of the knee and ankle. Percent body fat in the females was the only parameter that was significantly correlated with provincial ranking. The hematological status of the athletes was also determined, and the males had significantly greater hemoglobin, hematocrit and red blood cell counts, less mean corpuscular hemoglobin and smaller mean corpuscular volumes, than the females.

The response of serum lipids and lipoproteins to high intensity endurance training.

The response of serum lipids and lipoproteins to high intensity endurance training was studied in 12 males. Nine additional subjects were assigned to a control group. The mean age of participants was 25.0 years. Members of the exercise group trained on a bicycle ergometer at a power output equivalent to 80% of maximal oxygen uptake (VO2max), 4 times per week for 30 minutes, for 9 weeks. Nine weeks of detraining followed. Fasting blood samples and maximum bicycle tests were administered prior to the program, and at 3 week intervals, for determination of serum triglyceride, cholesterol, HDL-cholesterol, (VLDL + LDL) cholesterol, the ratio of HDL-cholesterol to total cholesterol, and VO2max. Per cent body fat, caloric intake, and the composition of the diet were also assessed during the training and detraining periods. Analysis of variance revealed no significant difference between or within groups for the lipid variables, per cent body fat, or diet parameters. A significant group X time interaction occurred in VO2max (p less than 0.05) indicating a cardiovascular training effect. These data suggest that 9 weeks of high intensity endurance training may not alter lipid or lipoprotein metabolism.

Physiologic response of nordic ski racers to three modes of sport specific exercise.

This study compared the response of cross-country skiers to 3 modes of sport-specific exercise. Eight racers completed 2 treadmill tests: ski-walking, and ski-walking with arm resistance provided by a pulley system, as well as a simulated skiing test. Although the average time to exhaustion was significantly less for the skimill test than for the other tests, there were no differences in the maximal responses to exercise. Heart rate, blood lactate, oxygen uptake, minute ventilation and breathing frequency were all significantly greater during the submaximal stages of the skimill test than during the 2 treadmill tests. Anaerobic threshold did not differ between the 2 treadmill tests; however, the addition of arm work significantly delayed its occurrence. Arm pulleys may not increase the specificity of, or add additional work to, a ski-walking test, but rather decrease the demand placed on the athlete by supporting body weight as elevation is increased.

Effect of interval training and detraining on anaerobic fitness in women.

Seventeen female volunteers (x age = 23.9 yr) participated in a 6 week investigation of the effect of high intensity interval training on anaerobic fitness. The subjects were randomly assigned to a treatment (exercise n = 9) or a control (no exercise n = 8) group. The training program consisted of 10 one minute work periods on the bicycle ergometer separated by one minute rest periods. This was done 3 days per week. The training intensity progressed from 110% of the experimental group's initial mean maximal oxygen intake (VO2 max) at week 1 to 15% of same group's initial mean VO2 max week 6. Improvements in the exercise group were significantly in VO2 max (+7.7%), peak post exercise blood lactate (-62.0%), maximum oxygen debt (+19.8%), and time of bicycle ride to exhaustion (+47.5%). The control group did not change significantly on any of the selected parameters. After 2 weeks of detraining oxygen debt decreased significantly to its pretraining value. The retention of increases in post exercise peak blood lactate and time of bicycle ride to exhaustion was 40% and 38% respectively. Twenty-four % of the increase in VO2 max induced by the training regime was retained.

Fitness and lifestyle parameters fail to predict back injuries in nurses.

Performance on fitness and back related isometric strength tests, as well as the response to a lifestyle questionnaire, were related to the subsequent occurrence of back injuries in 119 nurses. In all, 22% of subjects sustained injuries during the 18-month study. Injured nurses were more likely to be from high-risk wards and to have received worker's compensation pay for past back injuries. Fitness and lifestyle characteristics did not differ significantly between injured and not-injured groups. Using backward stepwise logistic regression, a model was developed that accounted for 41% of the variability between groups and predicted 67% of those injured. Prior compensation pay, smoking status, and job satisfaction were the most useful discriminators. It was concluded, however, that the fitness and lifestyle parameters measured did not effectively predict back injury in nurses.

The effect of exercise on bleeding time and local production of prostacyclin and thromboxane.

Exercise at a heart rate corresponding to 30% VO2max for 15 min was associated with an increase in the volume of bleeding time blood from a mean of 133 microliters before exercise to a mean of 218 microliters during and immediately after the exercise. There was similarly an increase in thromboxane B2 production from 6.40 nmol.l-1 before to 11.50 nmol.l-1. Most subjects also showed an increase in the length of the bleeding time and in the production of bleeding time 6-keto-PGF1 alpha. The extent of increase in the bleeding time and in production of 6-keto-PGF1 alpha was quite variable, with subjects showing the largest increases in bleeding time also demonstrating the greatest increases in 6-keto-PGF1 alpha (r = 0.76, P = 0.004). The ingestion of aspirin before exercise markedly inhibited basal bleeding time thromboxane B2 production and blocked the exercise-associated increments in thromboxane B2 and 6-keto-PGF1 alpha production. While the aspirin itself increased the length of the bleeding time, there was not any further increase associated with exercise. In contrast to the effects of acute short-term exercise, long-distance running was associated with a significant decrease in bleeding time, but no change in bleeding time blood volume, bleeding time thromboxane B2, or bleeding time 6-keto-PGF1 alpha. The results show that acute low-level exercise can be associated with significant changes in the volume of blood oozing from a bleeding time incision and in the amount of thromboxane production stimulated at the incisional site. Following exhaustive exercise of long duration, the above changes are no longer seen.