Low Levels Of Cardiorespiratory Fitness Research Articles

Aptidão cardiorrespiratória e associações com fatores de risco cardiovascular em adolescentes

OBJECTIVE: Maximum oxygen uptake is emerging as the measure of preference for expressing cardiorespiratory fitness for the purposes of surveys of physical activity, due to its greater objectivity and lower propensity to errors. Studies indicate that this measure is better correlated with cardiovascular diseases. This paper proposes to relate cardiovascular risk factors in adolescents with their level of cardiorespiratory fitness. METHODS: The study enrolled 380 schoolchildren, 177 boys and 203 girls (10 to 14 years old), who were divided into two groups according to their cardiorespiratory fitness. Anthropometric assessment was carried out, hemodynamic measurements (arterial pressure and heart rate) were taken, cardiopulmonary exercise testing was performed and biochemical tests were run (triglycerides, total and partial cholesterol). RESULTS: Among the boys, significant differences were observed between boys defined as and those classed as not weak in terms of baseline heart rate, maximum oxygen uptake, body mass index and triglycerides. Among the girls, significant differences were detected between baseline heart rates, maximum oxygen uptake and body mass indices. In both sexes, the group classified as exhibited a significantly greater number of overweight individuals that the not weak group (x2 = 25.242; p = 0.000; x2 = 12.683; p = 0.000, for boys and girls, respectively). A significant association between cardiorespiratory fitness and triglycerides (x2 = 3.944; p = 0.047) was observed among the boys only. CONCLUSIONS: A low level of cardiorespiratory fitness appears to have a negative influence on cardiovascular risk factors among adolescents, especially with relation to overweight in both sexes and to biochemical profile in the male sex, providing evidence of the need for early preventative interventions.

Body fat is associated with blood pressure in school-aged girls with low cardiorespiratory fitness: The European Youth Heart Study

To examine the association between anthropometric measurements of total and central adiposity and blood pressure in school-aged children, and to study whether these associations are modified by the levels of cardiorespiratory fitness. Systolic and diastolic blood pressure, weight, height, skinfold thickness and waist circumference were measured in 873 children aged 9-10 years participating in the Estonian and Swedish part of the European Youth Heart Study. Mean arterial pressure was calculated. Body mass index and skinfold thickness were used as markers of total adiposity, whereas waist circumference and waist-height ratio were used as markers of central adiposity. Cardiorespiratory fitness was estimated by a maximal ergometer bike test, and dichotomized into low and high levels. Markers of total and central adiposity were positively associated with blood pressure. The results from the regression models showed that the markers of total and central adiposity were significantly associated with systolic blood pressure in girls with low levels of cardiorespiratory fitness. Similar results were observed when mean arterial pressure was the outcome variable. None of the markers of total and central adiposity were significantly associated with blood pressure in girls with high levels of cardiorespiratory fitness or in boys with low or high levels of cardiorespiratory fitness. The results show a positive influence of simple anthropometric measurements of total and central adiposity on blood pressure, and suggest that higher cardiorespiratory fitness may attenuate the association between body fat and blood pressure in school-aged children.

The association between cardiorespiratory fitness and cardiovascular risk in adolescents

Maximum oxygen uptake is emerging as the measure of preference for expressing cardiorespiratory fitness for the purposes of surveys of physical activity, due to its greater objectivity and lower propensity to errors. Studies indicate that this measure is better correlated with cardiovascular diseases. This paper proposes to relate cardiovascular risk factors in adolescents with their level of cardiorespiratory fitness. The study enrolled 380 schoolchildren, 177 boys and 203 girls (10 to 14 years old), who were divided into two groups according to their cardiorespiratory fitness. Anthropometric assessment was carried out, hemodynamic measurements (arterial pressure and heart rate) were taken, cardiopulmonary exercise testing was performed and biochemical tests were run (triglycerides, total and partial cholesterol). Among the boys, significant differences were observed between boys defined as "weak" and those classed as "not weak" in terms of baseline heart rate, maximum oxygen uptake, body mass index and triglycerides. Among the girls, significant differences were detected between baseline heart rates, maximum oxygen uptake and body mass indices. In both sexes, the group classified as "weak" exhibited a significantly greater number of overweight individuals that the "not weak" group (chi2 = 25.242; p = 0.000; chi2 = 12.683; p = 0.000, for boys and girls, respectively). A significant association between cardiorespiratory fitness and triglycerides (chi2 = 3.944; p = 0.047) was observed among the boys only. A low level of cardiorespiratory fitness appears to have a negative influence on cardiovascular risk factors among adolescents, especially with relation to overweight in both sexes and to biochemical profile in the male sex, providing evidence of the need for early preventative interventions.

Effects of Different Doses of Physical Activity on Cardiorespiratory Fitness Among Sedentary, Overweight or Obese Postmenopausal Women With Elevated Blood Pressure

Low levels of cardiorespiratory fitness are associated with high risk of mortality, and improvements in fitness are associated with reduced mortality risk. However, a poor understanding of the physical activity-fitness dose response relation remains. To examine the effect of 50%, 100%, and 150% of the NIH Consensus Development Panel recommended physical activity dose on fitness in women. Randomized controlled trial of 464 sedentary, postmenopausal overweight or obese women whose body mass index ranged from 25.0 to 43.0 and whose systolic blood pressure ranged from 120.0 to 159.9 mm Hg. Enrollment took place between April 2001 and June 2005 in the Dallas, Tex, area. Participants were randomly assigned to 1 of 4 groups: 102 to the nonexercise control group and 155 to the 4-kcal/kg, 104 to the 8-kcal/kg, and 103 to the 12-kcal/kg per week energy-expenditure groups for the 6-month intervention period. Target training intensity was the heart rate associated with 50% of each woman's peak Vo2. The primary outcome was aerobic fitness assessed on a cycle ergometer and quantified as peak absolute oxygen consumption (Vo2abs, L/min). The mean (SD) baseline Vo2abs values were 1.30 (0.25) L/min. The mean (SD) minutes of exercising per week were 72.2 (12.3) for the 4-kcal/kg, 135.8 (19.5) for the 8-kcal/kg, and 191.7 (33.7) for the 12-kcal/kg per week exercise groups. After adjustment for age, race/ethnicity, weight, and peak heart rate, the exercise groups increased their Vo2abs compared with the control group by 4.2% in the 4-kcal/kg, 6.0% in the 8-kcal/kg, and 8.2% in the 12-kcal/kg per week groups (P<.001 for each vs control; P for trend <.001). There was no treatment x subgroup interaction for age, body mass index, weight, baseline Vo2abs, race/ethnicity, or baseline hormone therapy use. There were no significant changes in systolic or diastolic blood pressure values from baseline to 6 months in any of the exercise groups vs the control group. In this study, previously sedentary, overweight or obese postmenopausal women experienced a graded dose-response change in fitness across levels of exercise training. clinicaltrials.gov Identifier: NCT00011193.

Circuit Training Improves Submaximal Cardiorespiratory Fitness in Patients with Moderate to Severe Traumatic Brain Injury

Individuals with traumatic brain injury (TBI) are characterized by low levels of cardiorespiratory fitness and premature fatigue. Regular exercise is effective in enhancing both these parameters in healthy individuals and a variety of patient populations. PURPOSE: To examine the effects of circuit training on the submaximal physiological responses in patients with moderate to severe TBI. METHODS: Informed consent was obtained from 12 TBI in-patients (Glasgow Coma Scale score = 4.7 ± 1.9; time since injury 21 ± 9 months) who had completed a brain injury rehabilitation program at a rehabilitation hospital. The patients completed an average of 32 supervised circuit training sessions designed to enhance muscular strength/endurance and aerobic fitness in 12 weeks. Each session lasted approximately 1 hour with the aerobic component corresponding to 60% of the heart rate reserve. Subjects were evaluated prior to and following training at 60% of their pre-training VO2max during six minutes of cycle ergometry. Cardiac output was measured during the final minute by carbon dioxide rebreathing. Stroke volume and (a -v)O2diff were calculated from the data collected. Delta lactate concentrations were calculated from arterialized blood samples obtained at rest and 2 mins post exercise. RESULTS: Despite the exercise program, body mass increased significantly (p<.05) post training (75.0 ± 23.9 vs 78.8 ± 24.9 kgs). Consequently, the absolute oxygen uptake at the same submaximal power output increased significantly (p<.05; 0.93 ± 0.43 vs 1.02 ± 0.44 L/min). No significant changes (p>.05) were observed in the cardiac output (7.1 ±2.7vs7.1 ±2.1 L/min), ventilation rate (27.0 ± 10.7vs26.8 ±10.1 L/min) and delta lactate concentration (1.30 ± 0.98 vs 0.64 ± 0.67 mmol/L) following training. However, training induced significant reductions (p<.05) in the heart rate (117 ± 20.0 vs 107 ± 17 bpm) and ventilatory equivalent for oxygen (30.2 ± 7.3 vs 26.7 ± 4.8). As well, significant increases were observed in stroke volume (55.2 ±25.4vs61 ±25.1 ml/beat), oxygen pulse (8.0 ± 3.5 vs 9.6 ± 3.8 ml/beat) and (a-v)O2diff (14.0 ± 2.2 vs 15.1 ± 2.7 ml%) post training. CONCLUSION: Short term circuit training was effective in improving the cardiorespiratory fitness of patients with moderate to severe TBI due to both central and peripheral adaptations. Comprehensive rehabilitation programs should incorporate such training into the normal routine for this population. Funding: Alberta Heritage Foundation for Medical Research - Health Research Fund

Association of Increased Cardiorespiratory Fitness with Low Risk for Clustering of Metabolic Syndrome Components in Asymptomatic Men

From a preventive aspect, it is especially important to investigate the lifestyle risk factors associated with cardiovascular disease (CVD). The purpose of this study was to determine the relationship of increasing metabolic syndrome (MS) components across increasing levels of estimated cardiorespiratory fitness (CRF) in asymptomatic young to middle-aged men. We studied 449 consecutive asymptomatic men (47 +/- 7 years) who underwent a maximal treadmill exercise test according to the Bruce protocol. Cardiorespiratory fitness (CRF) was divided into tertiles based on metabolic equivalents (METs). The following MS components were studied: 1) waist circumference > 102 cm; 2) serum triglycerides > or = 150 mg/dL; 3) HDL cholesterol levels of < 40 mg/dL; 4) fasting blood glucose (FBG) > or = 110 mg/dL or 5) blood pressure > or = 130/85 mmHg or treated hypertension. Multinomial logistic regression was used to investigate the relationship between clustering of MS components and CRF as determined by metabolic equivalents (METs). We used polytomous logistic regression to determine the likelihood of clustering of increasing components of metabolic syndrome with intermediate (2nd tertile) and low (1st tertile) levels of CRF as compared to those with highest levels of CRF (3rd tertile). Overall in the study population, zero, 1, 2 and > or = 3 (i.e., metabolic syndrome) risk factors for MS were observed in 29% (n = 129), 26% (n = 118), 22% (n = 98) and 23% (n = 104) men, respectively. The mean METS achieved in the study population was 10 +/- 2 (range 4-20). Nearly half (49%) of individuals with the highest levels of CRF had no MS risk factors whereas only 18% of those with low CRF (METS < 9) had no MS risk factors. On the other end of the spectrum, the prevalence of MS (> or = 3 MS risk factors) increased significantly across decreasing levels of CRF (6, 22, 33% p < 0.0001 for trend). Multivariable polytomous logistic regression (adjusting for age, smoking, cholesterol-lowering therapy) demonstrated that individuals with low CRF (1st tertile of METS) compared to those with highest CRF had 3.1- (p = 0.001) and 11.8- (p < 0.0001) fold higher risk of having 2 and > or = 3 MS components, respectively. Similar results were observed when the analyses was repeated adjusting for Framingham risk score. Asymptomatic men with low levels of CRF have a greater likelihood for clustering of MS components and thus are at higher CVD risk. Further studies are needed to define the risk of cardiovascular disease in patients with intermediate levels of CRF and address which treatment strategies are most important given an individual's risk profile.

Age-Differences in GH Response to Exercise in Women: The Role of Fitness, BMI, and Insulin

Background:Little attention has been paid to the study of transient growth hormone (GH) responses to exercise in older women. We determined the effect of a single bout of exercise on GH in fit and unfit older (age 55 to 81 y; n = 19) and younger (age 18 to 25 y; n = 19) women.Methods:Exercise consisted of five 15-min intervals of treadmill exercise at 75% VO2peak. Blood samples were taken before, during, and following exercise for determination of plasma GH and insulin concentrations.Results:GH responses to exercise were attenuated in older compared with younger women (P &lt; 0.01); however, these age differences were minimized in older age by fitness level. Adjusted area under the curve for GH was 5.50 and 1.76 µg/L · 102 for fit and unfit older women (P &lt; 0.01), and 8.46 and 8.46 µg/L · 102 for fit and unfit younger women.Conclusions:Low levels of cardiorespiratory fitness in older women may require a greater relative exercise stimulus to augment meaningful GH responses.

Insulin and Blood Pressure

Hypertension has long been known to be more prevalent among obese subjects or in patients with diabetes, ie, in states of insulin resistance.1 After the demonstration that essential hypertension is an insulin-resistant state in its own right,2 it was logical to include hypertension in the insulin resistance syndrome,3 later transmuted into the metabolic syndrome.4 A large number of studies, both epidemiological and physiological, have explored this association and, more in general, the interrelationships between blood pressure and insulin action. Summarizing the available evidence—and critically analyzing its merits and pitfalls—is beyond the scope of this brief commentary. It may be nevertheless useful to recall a few general points. First, the association between insulin resistance and hypertension extends into the normal state as an association between insulin action on glucose metabolism and blood pressure levels5; this clearly speaks for the existence of multiple cross-talk between the 2 homeostatic systems. Second, longitudinal studies have confirmed that insulin resistance (as measured by its surrogate, fasting hyperinsulinemia) may precede the development of frank hypertension.6 The reverse temporal sequence, ie, hypertension antedating insulin resistance, has not been documented. Third, associations, even if fairly consistent, do …

Cardiorespiratory Fitness Estimation by Heart Rate Markers in Young, Sedentary Adults

0789 Low levels of cardiorespiratory fitness (CRF) and related autonomic dysfunction have been described as risk factors for cardiovascular events among cardiac patients and healthy adults. CRF can be roughly estimated by easy heart rate (HR) markers such as resting heart rate (HRrest), maximal heart rate (HRpeak), heart rate reserve (HRR) (HRR = HRpeak – HRrest) and heart rate recovery after 1 minute of maximal exercise (HRR1). PURPOSE: To determine the accuracy of common HR markers in predicting field test estimated CRF in young, sedentary, apparently healthy, Hispanic adults. METHODS: 61 (46 female, 15 male) young (19.63 ± 0.81 yrs), Hispanic, volunteer students participated in the study. Subjects initially underwent a pre-participation evaluation. HRrest was measured with the participants recumbent after 5-min rest and was obtained using a heart rate monitor (Polar Electro Oy). CRF was estimated by the 20m-Shuttle run test (20MST). Predicted CRF and HRpeak (heart rate monitor) were recorded at the moment of volitional exhaustion. Immediately after exercise, participants were helped to chairs. HRR1 was defined as the change from HRpeak to HR measured after 1 minute of recovery from exercise. Age-predicted maximal heart rate (PMHR) was 220 beats·min−1- age (yr). Two-tailed Pearson correlation coefficients were performed to determine the level of CRF estimation provided by the HR markers. RESULTS: Predicted CRF by the 20MST was (8.73 ± 1.71 METs). All subjects were free of chronotropic incompetence (defined as HRpeak < PMHR × 0.85). Average HRpeak was (192.09 ± 9.42 beats·min−1) corresponding to a (95.90 ± 4.64 %) of PMHR, according a maximal effort at the 20MST. Average HRrest and HRR1 where 79.88 ± 7.89 beats·min−1 and 27.68 ± 9.95 beats·min−1, respectively. Predicted CRF was significantly correlated (p<0.001) with the HRR (r = 0.46) and HRrest (r = −0.44). HRR1 showed a much lower prediction of CRF (r = 0.25 p = 0.050). No significant correlation was found for HRR1 and CRF in the gender subgroups. HRR was highly correlated with HRrest (r = −0.99, p<0.001). CONCLUSION: In our study group of young sedentary adults, CRF was better predicted by HRR and HRrest than by HRR1. HRR1 after maximal exercise, another indicator of autonomic cardiac control did not improve CRF estimation described by commonly used, HR measurements (HRR and HRrest).

Cardiorespiratory fitness and the incidence of type 2 diabetes: prospective study of Japanese men.

To investigate the association between cardiorespiratory fitness and the incidence of type 2 diabetes among Japanese men. This prospective cohort study was conducted in 4747 nondiabetic Japanese men, aged 20-40 years at baseline, enrolled in 1985 with follow-up to June 1999. Cardiorespiratory fitness was measured using a cycle ergometer test, and Vo(2max) was estimated. During a 14-year follow-up, 280 men developed type 2 diabetes. The age-adjusted relative risks of developing type 2 diabetes across quartiles of cardiorespiratory fitness (lowest to highest) were 1.0 (referent), 0.56 (95% CI 0.42-0.75), 0.35 (0.25-0.50), and 0.25 (0.17-0.37) (for trend, P < 0.001). After further adjustment for BMI, systolic blood pressure, family history of diabetes, smoking status, and alcohol intake, the association between type 2 diabetes risk and cardiorespiratory fitness was attenuated but remained significant (1.0, 0.78, 0.63, and 0.56, respectively; for trend, P = 0.001). These results indicate that a low cardiorespiratory fitness level is an important risk factor for incidence of type 2 diabetes among Japanese men.

CARDIORESPIRATORY FITNESS AND ALL-CAUSE AND CANCER MORTALITY IN JAPANESE MEN.

488 Limited data is available on the relationship between cardiorespiratory fitness(CRF) and mortality due to both cancer and all causes in Japanese men. We evaluated the CRF and risks of all-cause and cancer mortality of 9,677 Japanese men who were given a submaximal exercise test, a medical examination, and questionnaires on their health habits between 1982 and 1988. CRF was measured using a bicycle ergometer test, and maximal oxygen uptake was estimated. The average follow-up time was 15 years, producing a total of 147,429 person-years of observation. There were 231 deaths, with 110 deaths due to cancer. Relative risk and 95% confidence intervals for all-cause and cancer mortality were obtained using the Cox proportional hazards model. Taking into consideration age, body mass index, hypertension, urinary protein, cigarette smoking, and alcohol intake adjustment and using the lowest physical fitness (quintile I) group as a reference, the hazard ratios(95% CI) for quintiles I through V were: for all-cause mortality 1.0, 0.61(0.43-0.86), 0.58 (0.39-0.84), 0.48(0.30-0.76), 0.44(0.26-0.73), respectively; p for trend <0.001; for cancer mortality 1.0, 0.68(0.42-1.09), 0.46(0.26-0.81), 0.39(0.20-0.78), 0.27 (0.12-0.64), respectively; p for trend <0.001. These results indicate that a low CRF level is an important risk factor for all-cause and cancer mortality in Japanese men.

Physical activity patterns associated with cardiorespiratory fitness and reduced mortality: the Aerobics Center Longitudinal Study.

This study examined cross sectionally the physical activity patterns associated with low, moderate, and high levels of cardiorespiratory fitness. Physical activity was assessed by questionnaire in a clinic population of 13,444 men and 3972 women 20 to 87 years of age. Estimated energy expenditure (kcal.wk-1) and volume (min.wk-1) of reported activities were calculated among individuals at low, moderate, and high fitness levels (assessed by maximal exercise tests). Average leisure time energy expenditures of 525 to 1650 kcal.wk-1 for men and 420 to 1260 kcal.wk-1 for women were associated with moderate to high levels of fitness. These levels of energy expenditure can be achieved with a brisk walk of approximately 30 minutes on most days of the week. In fact, men in the moderate and high fitness categories walked between 130 and 138 min.wk-1, and women in these categories walked between 148 and 167 min.wk-1. Most individuals should be able to achieve these physical activity goals and thus attain a cardiorespiratory fitness level sufficient to result in substantial health benefits.

Dentists and Military Service in England

Relatively little has been reported about the physical characteristics, such as cardiorespiratory fitness (CRF) and body composition, of stimulant users. Identifying risk factors associated with the physical health of stimulant users is an important public health issue as new treatments should better address the entire range of health concerns experienced by this population.We examined cross-sectional data gathered at baseline from the STimulant Reduction Intervention using Dosed Exercise (STRIDE) study, a multisite randomized clinical trial that examined exercise as an adjunct to treatment as usual for individuals in residential treatment programs (RTPs). Clients were approached after intake to the RTP. Prior to randomization, eligible individuals underwent a comprehensive screening process that included medical screening, where CRF was assessed through a maximal exercise test (time on treadmill), and a series of baseline examinations assessing domains of substance use and mental health.Data from 295 individuals with recent stimulant use disorders were analyzed. The mean body mass index (BMI) and waist circumference (WC) and for all participants was 27.8 ± 5.7 kg/m2 and 93.5 ± 14.2 cm, respectively, while the mean time on treadmill was 13.7 ± 2.9 min. Few significant associations were observed between CRF, BMI, or WC and substance use and mental health measures.Stimulant users in this study presented with low CRF levels and would be considered overweight based on their BMI. These individuals would likely benefit from interventions that address both their stimulant use, as well as their physical health.