Cardiorespiratory Fitness In Adults Research Articles

Ageing affects the association between serum 25- hydroxyvitamin D concentrations and cardiorespiratory fitness in middle-aged and elderly men.

The studies investigated the association between serum 25-hydroxyvitamin D (25(OH)D) concentrations and cardiorespiratory fitness (CRF) are few, and the results are controversial. We aim to evaluate the association of serum 25(OH)D concentrations with CRF in adults, and assess whether the associations vary with ageing. The study included 78 middle-aged (30-64 years) and 83 elderly (65-79 years) Japanese men. Hand grip strength and leg extension power were measured using hand grip and leg dynamometers, respectively. CRF was measured via a maximal graded exercise test and quantified as the peak oxygen uptake (VO2peak). Fasting serum 25(OH)D concentrations were determined by enzyme-linked immunosorbant assay. Serum 25(OH)D concentrations were positively related to hand grip strength (r=0.331, p<0.001), leg extension power (r=0.353, p<0.001), CRF (r=0.285, p<0.001) in all adults after adjustment for age. Significant interaction between 25(OH)D and age on CRF was observed (p<0.05). Age-related reduction of CRF was prevented in high 25(OH)D group (p<0.05). In the elderly, subjects in high 25(OH)D group had higher CRF compared with those in low group (p<0.05). We found that serum 25(OH)D concentrations significantly related with leg extension power, hand grip strength and CRF after adjustment for age. The relationship of vitamin D and CRF was affected by ageing. Higher serum 25(OH)D concentrations are a key predictor for CRF in the elderly, but not in middle-aged men.

Winter Exercise Reduces Allergic Airway Inflammation: A Randomized Controlled Study.

Background: Physical exercise is often recommended as additional treatment for people suffering from allergic rhinitis and/or asthma, but less is known about the specific effects of recreational winter outdoor exercise on allergic airway inflammation. Methods: We performed a longitudinal, randomized controlled intervention study to investigate the effects of recreational winter exercise on allergic airway inflammation, quality of life, spirometry and cardiorespiratory fitness in adults suffering from allergic rhinitis and/or asthma. The exercise group participated in a ten-day winter sports program. The control group did not receive any intervention. Results: A significant improvement of fractional oral exhaled nitric oxide (FeNO; p = 0.008, day 10) and a significant decrease in FeNO after a single 4 h hiking tour (p < 0.001, time effect) were observed for the exercise group. The nasal eosinophilic cell count revealed a short-term reduction (p = 0.021, treatment effect) in the exercise group and for the visual analogue scale sustainable improvements in allergic symptoms (p < 0.001, day 60) were found. No adverse effects of outdoor winter exercise were observed. Conclusion: Recreational winter exercise at moderately cold temperatures reduces allergic airway inflammation measured as FeNO, nasal eosinophilic cell count and induces sustainable improvements in allergic symptoms.

Sitagliptin improves diastolic cardiac function but not cardiorespiratory fitness in adults with type 2 diabetes

BackgroundPeople with type 2 diabetes mellitus (T2D) have preclinical cardiac and vascular dysfunction associated with low cardiorespiratory fitness (CRF). This is especially concerning because CRF is a powerful predictor of cardiovascular mortality, a primary issue in T2D management. Glucagon-like pepetide-1 (GLP-1) augments cardiovascular function and our previous data in rodents demonstrate that potentiating the GLP-1 signal with a dipeptidyl peptidase-4 (DPP4) inhibitor augments CRF. Lacking are pharmacological treatments which can target T2D-specific physiological barriers to exercise to potentially permit adaptations necessary to improve CRF and thereby health outcomes in people with T2D. We therefore hypothesized that administration of a DPP4-inhibitor (sitagliptin) would improve CRF in adults with T2D. Methods and ResultsThirty-eight participants (64 ± 1 years; mean ± SE) with T2D were randomized in a double-blinded study to receive 100 mg/day sitagliptin, 2 mg/day glimepiride, or placebo for 3 months after baseline measurements. Fasting glucose decreased with both glimepiride and sitagliptin compared with placebo (P = 0.002). CRF did not change in any group (Placebo: Pre: 15.4 ± 0.9 vs. Post: 16.1 ± 1.1 ml/kg/min vs. Glimepiride: 18.5 ± 1.0 vs. 17.7 ± 1.2 ml/kg/min vs. Sitagliptin: 19.1 ± 1.2 vs. 18.3 ± 1.1 ml/kg/min; P = 0.3). Sitagliptin improved measures of cardiac diastolic function, however, measures of vascular function did not change with any treatment. ConclusionsThree months of sitagliptin improved diastolic cardiac function, however, CRF did not change. These data suggest that targeting the physiological contributors to CRF with sitagliptin alone is not an adequate strategy to improve CRF in people with T2D. Clinical trials registrationwww.clinicaltrials.gov NCT01951339.

Temporal Trends in the Cardiorespiratory Fitness of 2,525,827 Adults Between 1967 and 2016: A Systematic Review

To estimate international and national temporal trends in the cardiorespiratory fitness (CRF) of adults, and toexamine relationships between trends in CRF and trends in health-related, socioeconomic, and environmental indicators. Data were obtained from a systematic search of studies that explicitly reported temporal trends in the CRF of apparently healthy adults aged 18-59years. Sample-weighted temporal trends were estimated using best-fitting regression models relating the year of testing to mean CRF. Post-stratified population-weighted mean changes in percent and standardized CRF were estimated. Pearson's correlations were used to describe associations between linear trends in CRF and linear trends in health-related, socioeconomic, and environmental indicators. 2,525,827 adults representing eight high- and upper-middle-income countries between 1967 and 2016 collectively showed a moderate decline of 7.7% (95% CI - 8.4 to - 7.0) or 1.6% per decade (95% CI - 1.7 to - 1.5). Internationally, CRF improved in the 1960s and 1970s, and progressively declined at an increasing rate thereafter. Declines were larger for men than for women, and for young adults (< 40years) than for middle-aged adults (≥ 40years). All countries experienced declines in CRF with a very strong negative correlation between CRF trends and obesity trends. There has been a meaningful decline in the CRF of adults since 1980, which has progressively increased in magnitude over time, suggestive of a corresponding decline in population health. Continuous national and international surveillance systems are needed in order to monitor health and fitness trends, especially among low- and middle-income countries for which data do not currently exist. PROSPERO registration number: CRD42013003678.

Individual and interpersonal correlates of cardiorespiratory fitness in adults - The case of Germany

Individual and interpersonal correlates of cardiorespiratory fitness in adults - The case of Germany

Individual and interpersonal correlates of cardiorespiratory fitness in adults - The case of Germany

Individual and interpersonal correlates of cardiorespiratory fitness in adults - The case of Germany

Patterns of accelerometer-based sedentary behavior and their association with cardiorespiratory fitness in adults.

We aimed to identify patterns of sedentary behavior (SB) and examined whether cardiorespiratory fitness differs between classes with distinct patterns of SB. One hundred and seventy participants (57% women, mean age = 56.4 years) received accelerometry monitoring for 7 days. Prior to accelerometry assessment, cardiorespiratory fitness was assessed by peak oxygen uptake (VO2peak ). VO2peak was directly measured during a symptom-limited cardiopulmonary exercise testing on a cycle ergometer. Patterns in accelerometer data were classified based on time spent in SB per day using growth mixture modeling. Model-implied class-specific VO2peak means were compared using adjusted equality test of means. Growth mixture modeling revealed four patterns of SB: "High, stable" (n = 120, M = 724.9 min/d), "Low, increase" (n = 14, M = 622.2 min/d), "Low, decrease" (n = 11, M = 540.2 min/d), and "High, decrease" (n = 25, M = 694.8 min/d). Persons in class "High, stable" had significantly lower VO2peak values (M = 25.0 mL/kg/min, SD = 0.6) compared to persons in class "Low, increase" (M = 30.5 mL/kg/min, SD = 3.6; P = 0.001), in class "Low, decrease" (M = 30.1 mL/kg/min, SD = 5.0; P = 0.009), and in class "High, decrease" (M = 29.6 mL/kg/min, SD = 5.9; P = 0.032). No differences among the other classes were found. We identified four classes of individuals with distinct patterns of SB and showed that VO2peak partially differs between classes. Especially, individuals with stable high SB levels throughout the week might be addressed in public health recommendations and interventions.

The Association Between Self-Rated Fitness and Cardiorespiratory Fitness in Adults

To assess criterion validity of a single item question on self-rated physical fitness against objectively measured cardiorespiratory fitness. From the Health2008 study 749 men and women between 30 and 60 years of age rated their fitness as excellent, very good, good, fair or poor. Cardiorespiratory fitness was estimated with the watt-max test. Agreement between self-rated and objectively measured physical fitness was assessed by Cohen's weighted kappa coefficient. Correlation was determined by Goodman & Kruskal's gamma correlation coefficient. All analyses were stratified according to gender. Data from 323 men and 426 women were analysed. There was a slight agreement between self-rated and objectively measured fitness in men (weighted kappa: 0.18, [95%CI: 0.13;0.23]) and a fair agreement in women (weighted kappa: 0.27, [95%CI: 0.22;0.32]). In both genders, self-rated fitness was positively correlated with objectively measured fitness (moderate correlation; gamma correlation coefficient for men: 0.63 [95%CI: 0.54;0.72] and women: 0.67 [95%CI: 0.59;0.75]). There was a slight to fair agreement and moderate, positive correlations between self-rated physical fitness and watt-max estimated cardiorespiratory fitness. Hence, a single-item question on physical fitness may be a cost-effective method of assessing fitness in large population studies, but is not valid for individual assessments.

Why are some people more fit than others? Correlates and determinants of cardiorespiratory fitness in adults: protocol for a systematic review

BackgroundCardiorespiratory fitness (CRF) is a physical condition that is now well established as a predictor of numerous adverse health outcomes, independent of physical activity levels. In order to be able to improve CRF at the population level and to develop effective interventions and public health programmes, it is important to understand why some people are more fit than others. Therefore, the primary aim of the systematic review described in this protocol is to examine individual and interpersonal factors that are correlated with or determine CRF among adults.MethodsThe review will focus on quantitative studies that investigate any personal and interpersonal correlates and/or determinants of objectively measured CRF among the general, non-symptomatic, non-institutionalized adult population (aged 18–65 years) worldwide. The databases MEDLINE, Embase, and Cochrane Library will be searched to identify all relevant published journal articles, and Google Scholar and Scopus will be searched for grey literature. Studies where CRF is not an outcome variable and experimental studies where participants specifically receive a fitness intervention that increases CRF will be excluded. For each study, data extracted will include, among other variables, study characteristics, methodology for selecting participants into the study as well as the participants’ demographic characteristics, types of correlates and determinants of CRF investigated and their measurement methods, the objective measure of CRF used and its measurement method and validity, and the main reported results on the association between the correlates or determinants and CRF. In addition, observational studies will be assessed for methodological quality and risk of bias using a customized version of the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies by the National Heart, Lung, and Blood Institute. Experimental studies will be assessed using the 27-item Downs and Black “Checklist for Measuring Study Quality”. The final results will be presented as a narrative synthesis of the main findings of all included studies.DiscussionBy consolidating and synthesizing the current research on possible individual and interpersonal correlates and determinants of CRF among adults worldwide, we aim to aid future public health actions, as well as identify gaps in our full understanding of what influences CRF.Systematic review registrationPROSPERO CRD42017055456.

Abstract P139: The Association of Cardiorespiratory Fitness With Cardiometabolic Risk Factors and Markers of Endothelial Function in the Study of Latino Youth (SOL Youth)

Background: Adult cardiorespiratory fitness (CRF) is associated with lower risk of cardiovascular disease and mortality. However, there is scarce information in youth about the role of CRF in subclinical measures of CVD, such as endothelial function. In this study we tested associations of cardiometabolic factors (CMF) and biomarkers of endothelial function (e-selectin; PAI-1). Methods: We included 1,380 participants (699 girls and 681 boys) aged 8-16 years from SOL Youth. CRF was assessed by a step test and VO2 max was estimated. CMF included fasting glucose, lipids, blood pressure. Inflammatory markers included hs-CRP and adiponectin. Associations of CRF with e-selectin and PAI-1 were assessed with multiple linear regression models, adjusting for potential confounders: actigraphy derived physical activity (PA) and sedentary time (SED), adiposity, and socio-demographic factors. Odds ratios were derived for the association of CRF and having ≥3 CVD risk factors (RF)(defined by elevated age/sex appropriate BP, lipids, glucose, and obesity), adjusted for confounders. Analyses accounted for complex survey design. Results: Boys and US-born youth were more likely to have higher CRF. CRF was positively correlated with PA (r=.23, p&lt;.0001) but inversely correlated with SED (r=-.10, p=.001), BMIz-score (r=-.37, p&lt;.0001), waist circumference (WC)(r=-.38, p&lt;.0001), and %body fat (r=-.43, p&lt;.0001). In multivariate models adjusting for socio-demographic factors, PA and SED (model 1), CRF was strongly and inversely associated with markers of endothelial function, inflammation, and CMF, which were attenuated when adjusting for WC (model 2)(Table 1). The odds of having ≥3 CVD RF was significantly lower at highest quartiles of fitness (ORs Q2=.47, Q3=.68, Q4=.35, p-trend=.001) after adjusting for confounders and WC. Conclusions: Among Latino youth, CRF appears to be a strong protective factor for endothelial dysfunction and CMF. Strategies to improve CRF may be a useful approach for improving cardiovascular health in youth.

The effects of exercise modality and intensity on energy expenditure and cardiorespiratory response in adults with obesity and treated obstructive sleep apnoea.

To inform recommendations for the exercise component of a healthy lifestyle intervention for adults with obesity and treated obstructive sleep apnoea (OSA), we investigated the total energy expenditure (EE) and cardiorespiratory response to weight-supported (cycling) and unsupported (walking) exercise. Individuals with treated OSA and a body mass index (BMI) > 30 kg/m2 performed an incremental cardiopulmonary exercise test on a cycle ergometer and a treadmill to determine the peak oxygen uptake [Formula: see text]. Participants subsequently completed two endurance tests on each modality, matched at 80% and 60% of the highest [Formula: see text] determined by the incremental tests, to intolerance. The cardiorespiratory response was measured and total EE was estimated from the [Formula: see text]. Sixteen participants completed all six tests: mean [SD] age 57 [13] years and median [IQ range] BMI 33.3 [30.8-35.3] kg/m2. Total EE during treadmill walking was greater than cycling at both high (158 [101] vs. 29 [15] kcal; p < 0.001) and moderate (178 [100] vs. 85 [59] kcal; p = 0.002) intensities, respectively, with similar cardiorespiratory responses and pattern of EE during rest, exercise and recovery. Contrary to current guidelines, walking might be the preferred training modality to achieve the combination of weight loss and increased cardiorespiratory fitness in adults with obesity and treated OSA.

Decreased physical activity and cardiorespiratory fitness in adults with ankylosing spondylitis: a cross-sectional controlled study.

The health benefits of physical activity (PA) in the general population are numerous; however, few studies have measured PA among adults with ankylosing spondylitis (AS). The aims of this study were to: (1) objectively measure the PA levels and cardiorespiratory fitness of adults with AS and compare these to population controls, and (2) examine the relationships between PA, cardiorespiratory function and condition-specific outcomes. This cross-sectional study included participants (>18 years) meeting the modified New York criteria for AS, and matched population controls. Exclusion criteria were the presence of comorbidities limiting PA, or recent changes in medication usage. Participants completed clinical questionnaires assessing disease activity, physical function and quality of life. Tri-axial accelerometers recorded habitual PA over 1 week. Cardiorespiratory fitness was assessed by submaximal treadmill test with breath-by-breath gas analysis and heart rate monitoring. Thirty-nine adults with AS and 39 controls were recruited. The AS group spent significantly less time performing vigorous-intensity PA than controls [mean difference (95 % CI) 1.8 min/day (1.2-2.7)] and performed significantly fewer bouts of health-enhancing PA [1.7 min/day (1.1-2.5)]. The AS group had significantly lower predicted VO(2MAX) than controls [6.0 mL kg(-1) min(-1) (1.8-10.1)]. PA was associated with aerobic capacity. Sedentary time was associated with disease activity and physical function. Adults with AS participate in less health-enhancing PA than population controls. Fewer than half meet PA recommendations, despite exercise being a key component of AS management. Explorations of PA behaviour and strategies to increase PA participation are needed.

Cardiorespiratory fitness and cognitive function in midlife: neuroprotection or neuroselection?

A study was undertaken to determine whether better cognitive functioning at midlife among more physically fit individuals reflects neuroprotection, by which fitness protects against age-related cognitive decline, or neuroselection, by which children with higher cognitive functioning select more active lifestyles. Children in the Dunedin Longitudinal Study (N = 1,037) completed the Wechsler Intelligence Scales and the Trail Making, Rey Delayed Recall, and Grooved Pegboard tasks as children and again at midlife (age = 38 years). Adult cardiorespiratory fitness was assessed using a submaximal exercise test to estimate maximum oxygen consumption adjusted for body weight in milliliters/minute/kilogram. We tested whether more fit individuals had better cognitive functioning than their less fit counterparts (which could be consistent with neuroprotection), and whether better childhood cognitive functioning predisposed to better adult cardiorespiratory fitness (neuroselection). Finally, we examined possible mechanisms of neuroselection. Participants with better cardiorespiratory fitness had higher cognitive test scores at midlife. However, fitness-associated advantages in cognitive functioning were already present in childhood. After accounting for childhood baseline performance on the same cognitive tests, there was no association between cardiorespiratory fitness and midlife cognitive functioning. Socioeconomic and health advantages in childhood and healthier lifestyles during young adulthood explained most of the association between childhood cognitive functioning and adult cardiorespiratory fitness. We found no evidence for a neuroprotective effect of cardiorespiratory fitness as of midlife. Instead, children with better cognitive functioning are selecting healthier lives. Fitness interventions may enhance cognitive functioning. However, observational and experimental studies testing neuroprotective effects of physical fitness should consider confounding by neuroselection.

The influence of active and passive smoking on the cardiorespiratory fitness of adults

&#x0D; &#x0D; &#x0D; &#x0D; Background: The aim of this study was to analyze the influence of active and passive smoking on cardiorespiratory responses in asymptomatic adults during a sub-maximal-exertion incremental test.&#x0D; Methods: The participants (n = 43) were divided into three different groups: active smokers (n = 14; aged 36.5 ± 8 years), passive smokers (n = 14; aged 34.6 ± 11.9 years) and non-smokers (n = 15; aged 30 ± 8.1 years). They all answered the Test for Nicotine Dependence and underwent anthropometric evaluation, spirometry and ergospirometry according to the Bruce Treadmill Protocol.&#x0D; Results: VO2max differed statistically between active and non-smokers groups (p &lt; 0.001) and between non-smokers and passive group (p=0.022). However, there was no difference between the passive and active smokers groups (p=0.053). Negative and significant correlations occurred between VO2max and age (r = − 0.401, p = 0.044), percentage of body fat (r = − 0.429, p = 0.011), and waist circumference (WC) (r = − 0.382, p = 0.025).&#x0D; Conclusion: VO2max was significantly higher in non-smokers compared to active smokers and passive smokers. However, the VO2max of passive smokers did not differ from active smokers.&#x0D; &#x0D; &#x0D; &#x0D;

Metabolic Surgery Is No Longer Just Bariatric Surgery

Metabolic Surgery Is No Longer Just Bariatric Surgery

The influence of active and passive smoking on the cardiorespiratory fitness of adults.

BackgroundThe aim of this study was to analyze the influence of active and passive smoking on cardiorespiratory responses in asymptomatic adults during a sub-maximal-exertion incremental test.MethodsThe participants (n = 43) were divided into three different groups: active smokers (n = 14; aged 36.5 ± 8 years), passive smokers (n = 14; aged 34.6 ± 11.9 years) and non-smokers (n = 15; aged 30 ± 8.1 years). They all answered the Test for Nicotine Dependence and underwent anthropometric evaluation, spirometry and ergospirometry according to the Bruce Treadmill Protocol.ResultsVO2max differed statistically between active and non-smokers groups (p < 0.001) and between non-smokers and passive group (p=0.022). However, there was no difference between the passive and active smokers groups (p=0.053). Negative and significant correlations occurred between VO2max and age (r = - 0.401, p = 0.044), percentage of body fat (r = - 0.429, p = 0.011), and waist circumference (WC) (r = - 0.382, p = 0.025).ConclusionVO2max was significantly higher in non-smokers compared to active smokers and passive smokers. However, the VO2max of passive smokers did not differ from active smokers.

The MILE study: a motivational, individual and locally anchored exercise intervention among 30–49 year-olds with low levels of cardiorespiratory fitness: a randomised controlled study in primary care

BackgroundLow levels of cardiorespiratory fitness are associated with high risk of non-communicable diseases and all-cause mortality. Physical activity level is the primary determinant of cardiorespiratory fitness in adults. However, knowledge on how to motivate people to engage in physical activity and maintain an active lifestyle is lacking. This study aims to investigate whether a motivational, individual, and locally anchored exercise intervention, in primary care, can improve cardiorespiratory fitness in 30 to 49 year olds with a low or very low cardiorespiratory fitness.Methods/DesignTwo-armed randomised controlled trial with 6 and 12 months follow-up. The primary outcome is cardiorespiratory fitness estimated via a maximal incremental exercise test. Secondary outcomes include physical activity level and sedentary behavior (objectively measured), self-reported physical activity, biochemical parameters (HbA1C, HDL- and LDL-cholesterol, and triglyceride), anthropometric parameters and health-related quality of life. A total of 236 participants with low levels of cardiorespiratory fitness classified at a local health check programme will be randomised. The intervention consists of four motivational interviews, a six months membership to a sport club, and a global positioning watch to upload training activity to Endomondo.com. The comparison group will receive standard care: a one hour motivational interview followed by another interview if requested. Effects will be estimated by evaluating the differences in mean changes in cardiorespiratory fitness between the two groups.DiscussionIn new and innovative ways the focus of this study will be to improve cardiorespiratory fitness among a 30–49 year-old at-risk group using social media, Global Positioning System-technology, on-going personal support and individually tailored physical activity.Trial registrationClinicalTrials.gov (no.NCT01801956).

Genetic, Maternal and Placental Factors in the Association between Birth Weight and Physical Fitness: A Longitudinal Twin Study

BackgroundAdult cardiorespiratory fitness and muscle strength are related to all-cause and cardiovascular mortality. Both are possibly related to birth weight, but it is unclear what the importance is of genetic, maternal and placental factors in these associations.DesignPeak oxygen uptake and measures of strength, flexibility and balance were obtained yearly during adolescence (10–18 years) in 114 twin pairs in the Leuven Longitudinal Twin Study. Their birth weights had been collected prospectively within the East Flanders Prospective Twin Survey.ResultsWe identified linear associations between birth weight and adolescent vertical jump (b = 1.96 cm per kg birth weight, P = 0.02), arm pull (b = 1.85 kg per kg birth weight P = 0.03) and flamingo balance (b = −1.82 attempts to stand one minute per kg birth weight, P = 0.03). Maximum oxygen uptake appeared to have a U-shaped association with birth weight (the smallest and largest children had the lowest uptake, P = 0.01), but this association was no longer significant after adjustment for parental BMI. Using the individual twin’s deviation from his own twin pair’s average birth weight, we found positive associations between birth weight and adolescent vertical jump (b = 3.49, P = 0.0007) and arm pull (b = 3.44, P = 0.02). Δ scores were calculated within the twin pairs as first born twin minus second born twin. Δ birth weight was associated with Δ vertical jump within MZ twin pairs only (b = 2.63, P = 0.009), which indicates importance of placental factors.ConclusionsWe found evidence for an association between adolescent physical performance (strength, balance and possibly peak oxygen uptake) and birth weight. The associations with vertical jump and arm pull were likely based on individual, more specifically placental (in the case of vertical jump) factors. Our results should be viewed as hypothesis-generating and need confirmation, but potentially support preventive strategies to optimize birth weight, for example via placental function, to target later fitness and health.

Cardiorespiratory Fitness Is Associated with Hard and Light Intensity Physical Activity but Not Time Spent Sedentary in 10–14 Year Old Schoolchildren: The HAPPY Study

BackgroundSedentary behaviour is a major risk factor for developing chronic diseases and is associated with low cardiorespiratory fitness in adults. It remains unclear how sedentary behaviour and different physical activity subcomponents are related to cardiorespiratory fitness in children. The purpose of this study was to assess how sedentary behaviour and different physical activity subcomponents are associated with 10–14 year-old schoolchildren's cardiorespiratory fitness.Methods135 schoolchildren (81 girls, 12±1 year) completed 7-day minute-by-minute habitual physical activity monitoring using triaxial accelerometers and undertook a maximal cardiorespiratory fitness test.ResultsAfter controlling for sex, age, ethnicity, socioeconomic status and total wear time, light physical activity (1.5–2.9 METs) was negatively associated (β = −.24, p<.01) and hard physical activity (≥9 METs) positively associated (β = .45, p<.001) with cardiorespiratory fitness. Vigorous and hard physical activity were associated with cardiorespiratory fitness for boys (F = 5.64, p<.01) whereas light, moderate and hard physical activity were associated with physical fitness for girls (F = 10.23, p<.001). No association was found between sedentary time and cardiorespiratory fitness (r = −.13, p>.05). Sedentary to active transitions revealed little variability between cardiorespiratory fitness tertiles.ConclusionsHard physical activity (≥9 METs) holds greater potential for cardiorespiratory fitness compared to physical activity of lower intensities. There was no relationship between sedentary behaviour and cardiorespiratory fitness. These findings suggest that, for children, advice should focus on higher intensity physical activity and not sedentary behaviour as a means to maintain or improve cardiorespiratory fitness. Future research should explore longitudinal relationships between hard physical activity, cardiorespiratory fitness and health parameters.

The effect of walking on cardiorespiratory fitness in adults with knee osteoarthritis

Walking programs alone or in combination with behavioral interventions have proven effective at improving quality of life among older adults with osteoarthritis (OA). It is unclear, however, whether the combination of both of these treatments is more effective at improving cardiorespiratory fitness in older adults with knee OA than a walking program alone or than unsupervised self-directed walking. In this study, we assessed cardiorespiratory fitness with 3 programs: a structured supervised community-based aerobic walking program with a behavioral intervention (WB; n = 41); a supervised program of walking only (W; n = 42); and an unsupervised self-directed walking program (n = 32). We measured maximal oxygen uptake (V̇O2peak), exercise test duration, and workload, heart rate, and ventilation at maximum aerobic capacity in older adults with knee OA after 6 months of WB, W, or self-directed walking. Overall, V̇O2peak improved by 4% in female walkers (+0.9 ± 2.5 mL O2·kg(-1)·min(-1); p < 0.001) and 5% in male walkers (+1.3 ± 2.7 mL O2·kg(-1)·min(-1); p < 0.001), and the change in fitness was similar with all 3 walking interventions. In conclusion, low- to moderate-intensity walking may improve and (or) prevent decrements in cardiorespiratory fitness in older adults with OA. This response was comparable in supervised walkers with and without a behavioral intervention and in unsupervised self-directed walkers.