Fatness is a better predictor of cardiovascular disease risk factor profile than aerobic fitness in healthy men

The independent and joint associations of cardiorespiratory fitness and adiposity with cardiometabolic risk factors and metabolic syndrome in United States college students

Objective To examine the association of CRF and adiposity with cardiometabolic risk factors and metabolic syndrome among emerging adults. Participants: 5681 (60.1% Men; 21 ± 1years) college students from a large university located in the northeast of the United States. Methods: Participants completed an objective health assessment that involved the assessment cardiometabolic risk factors, CRF, and adiposity. Data of 5681 students' (60.1% Men; 21 ± 1years) who had CRF, adiposity, all risk factors necessary to determine metabolic syndrome evaluated were analyzed using logistic regression analyses. Results: Poor CRF and elevated adiposity were associated with cardiometabolic risk factors and metabolic syndrome regardless of sex, with the association between adiposity and risk factors found to be stronger compared to CRF. Conclusions: Targeted and tailored screening and interventions are urgently needed to reduce adiposity and increase CRF to avoid serious short and long-term negative health outcomes in this population.

Cardiorespiratory fitness and submaximal exercise dynamics in normal-weight obesity and metabolically healthy obesity

PURPOSE

Cardiorespiratory fitness (CRF) is critical for cardiovascular health. Normal-weight obesity (NWO) and metabolically healthy obesity (MHO) may be at increased risk for cardiovascular disease, but a comparison of CRF and submaximal exercise dynamics against rigorously defined low- and high-risk groups is lacking.

METHODS

Four groups (N = 40; 10/group) based on body mass index (BMI), body fat %, and metabolic syndrome (MetS) risk factors were recruited: healthy controls (CON; BMI 18.5-24.9 kg/m2, body fat < 25% [M] or < 35% [F], 0-1 risk factors), NWO (BMI 18.5-24.9 kg/m2, body fat ≥ 25% [M] or ≥ 35% [F]), MHO (BMI > 30 kg/m2, body fat ≥ 25% [M] or ≥ 35% [F], 0-1 risk factors), or metabolically unhealthy obesity (MUO; BMI > 30 kg/m2, body fat ≥ 25% [M] or ≥ 35% [F], 2 + risk factors). All participants completed a V ˙ O2peak test on a cycle ergometer.

RESULTS

V ˙ O2peak was similarly low in NWO (27.0 ± 4.8 mL/kg/min), MHO (25.4 ± 6.7 mL/kg/min) and MUO (24.6 ± 10.0 mL/kg/min) relative to CON (44.2 ± 11.0 mL/kg/min) when normalized to total body mass (p's < 0.01), and adjusting for fat mass or lean mass did not alter these results. This same differential V ˙ O2 pattern was apparent beginning at 25% of the exercise test (PGroup*Time < 0.01).

CONCLUSIONS

NWO and MHO had similar peak and submaximal CRF to MUO, despite some favorable health traits. Our work adds clarity to the notion that excess adiposity hinders CRF across BMI categories.

CLINICALTRIALS

gov registration: NCT05008952.

The relationship between cardiorespiratory fitness and blood pressure among airline pilots: a mediation analysis of body composition

OBJECTIVE

Blood pressure (BP), cardiorespiratory fitness (CRF), and body composition are independently associated with health outcomes, yet the relationship between these variables has not been explored among airline pilots. The aim of this study was to evaluate the relationship between CRF and BP, and further examine whether the relationship is mediated by body composition.

METHODS

A cross-sectional study was conducted among 356 airline pilots in New Zealand. We measured height, body mass, BP, waist circumference, skinfolds, and CRF (via a WattBike cycle ergometer submaximal VO 2max test). Partial correlation coefficients were estimated to examine the relationships between all variables while controlling for age and sex. Haye's PROCESS macro and the Sobel test were utilized for the mediation analysis.

RESULTS

All body composition variables (body mass index, waist circumference and body fat percentage) were positively correlated with all BP variables (systolic pressure, diastolic pressure and mean arterial pressure) ( P  < 0.001). CRF was negatively correlated with all body composition and BP variables ( P  < 0.001). The Sobel test and indirect effect were significant ( P  < 0.001), confirming that all body composition variables partially mediate the relationship between CRF and all blood pressure variables.

CONCLUSION

Lower CRF is associated with higher blood pressure, and body composition partially mediates the relationship between these health risk factors. These findings highlight the importance of physical fitness and healthy body composition in the management of blood pressure among this occupational group.

The association between daytime napping and risk of type 2 diabetes is modulated by inflammation and adiposity: Evidence from 435 342 UK-Biobank participants

BACKGROUND

Existing evidence concerning the relationship between daytime napping and type 2 diabetes (T2D) is inconsistent, and whether the effects of napping differ by body fat percentage (BFP) and C-reactive protein (CRP) is unclear. We aimed to investigate the association between daytime napping frequency and T2D risk and whether such an association was modified by BFP and CRP.

METHODS

We included 435 342 participants free of diabetes from the UK Biobank. Participants were categorized as nonnappers, occasional nappers, and frequent nappers based on napping frequency, and BFP/CRP was divided into quartiles. Cox proportional hazards models were used.

RESULTS

During a median follow-up of 9.2 years, 17 592 T2D cases occurred. Higher frequency of daytime napping was significantly associated with an increased risk of T2D. Compared with nonnappers, the adjusted hazard ratios (HRs) for occasional nappers and habitual nappers were 1.28 (95% confidence interval [CI]: 1.24-1.32) and 1.49 (95% CI: 1.41-1.57), respectively. There was a significant additive and multiplicative interaction (relative excess risk due to interaction [RERI] = 0.490, 95% CI 0.307-0.673; p for multiplicative interaction <.001) between napping and BFP, whereby a higher hazard of T2D associated with more frequent napping was greatest among participants in the highest BFP quartile (HR = 4.45, 95% CI: 3.92-5.06). The results for CRP were similar (RERI = 0.266, 95% CI: 0.094-0.439; p for multiplicative interaction <.001).

CONCLUSIONS

Higher daytime napping frequency is associated with an increased T2D risk, and such relationships are modified by BFP and CRP. These findings underscore the importance of adiposity and inflammation control to mitigate diabetes risk.

Effects of fitness and fatness on age-related arterial stiffening in people with type 2 diabetes

People with type 2 diabetes (T2D) are at a greater risk of cardiovascular disease than the general population. Both non-modifiable (age) and modifiable (low aerobic fitness, high body fatness) factors are separately predictive of cardiovascular risk, although they often occur concomitantly. This study aimed to examine the (1) association between age and arterial stiffness, a subclinical marker of cardiovascular risk; and (2) effects of body fatness and aerobic fitness on age-related increases in arterial stiffness in people with T2D. Data from 64 individuals with T2D (age 59.8 ± 8.7 years, 40% female, HbA1c 8.4 ± 1.6%) were included in this cross-sectional analysis. Carotid-femoral pulse wave velocity (cfPWV) was used to quantify arterial stiffness. Aerobic fitness (relative V̇O2peak ) was determined via indirect calorimetry during maximal exercise testing. Central body fatness was determined using waist circumference. Data were analysed using hierarchical multiple regressions. After adjustment for sex and duration of T2D, each one standard deviation (SD) increase in age (8.68 years) was associated with a 0.63 m·s-1 increase in cfPWV (β = 0.416, p = 0.001). Following adjustment for aerobic fitness and body fatness, the standardized β was unchanged (0.417). A one SD increase in waist circumference (13.9 cm) and relative V̇O2peak (5.3 ml·kg-1 ·min-1 ) were associated with a similar magnitude of difference in cfPWV (0.47 m·s-1 and -0.44 m·s-1 , respectively). Therefore, age is a significant correlate of increased arterial stiffness in T2D, with higher aerobic fitness attenuating, and higher body fatness exacerbating, this increase. Interventions aimed at improving cardiovascular outcomes in people with T2D should target both increased aerobic fitness and reduced body fatness.

Bicycle Touring 480 km in Seven Days: Effects on Body Composition and Physical Fitness-A Case Study

Bicycle touring as a modality of physical activity that involves whole-body cardiorespiratory and metabolic functions could be a potential strategy to improve body composition and cardiorespiratory fitness. Therefore, the aim of the current study was to investigate the effects of 7-days bicycle touring activity on body composition and physical fitness. A total of 13 individuals (three women) participated in this quasi-experimental study. The participants were evaluated at baseline and were tracked for up to 12 days after the intervention. The intervention consisted of a 480 km bicycle touring route performed over 8 days. Body weight and body composition (i.e., fat mass and lean mass) were assessed using a bioelectrical impedance analyser. Physical fitness was measured using the International Fitness Scale questionnaire. We conducted a repeated-measures analysis of variance to determine changes in body weight and body composition and paired sample t-tests to analyse changes in physical fitness. Significant differences in fat mass were observed between the baseline and both post-intervention (p = 0.003) and re-test values (p = 0.031). Significant differences were also noted in lean mass between the baseline and post-intervention values (p = 0.003), whereas no significant changes were observed when compared the baseline and re-test values (p = 0.178). Significant differences were obtained in cardiorespiratory fitness when comparing the baseline with the post-intervention values (p = 0.016), whereas no significant differences were noted in general fitness, muscular strength, speed/agility, and flexibility (all p > 0.05). In conclusion, a 7-day bicycle touring intervention can significantly reduce fat mass and increase lean mass and cardiorespiratory fitness in healthy individuals.

Scaling VO2max to body size differences to evaluate associations to CVD incidence and all-cause mortality risk

Objective

To evaluate and compare ratio and allometric scaling models of maximal oxygen consumption (VO₂max) for different body size measurements in relation to cardiovascular disease (CVD) incidence and all-cause mortality.

Methods

316 116 individuals participating in occupational health screenings, initially free from CVD, were included. VO₂max was estimated using submaximal cycle test. Height, body mass and waist circumference (WC) were assessed, and eight different scaling models (two evaluated in a restricted sample with WC data) were derived. Participants were followed in national registers for first-time CVD event or all-cause mortality from their health screening to first CVD event, death or 31 December 2015.

Results

Increasing deciles of VO₂max showed lower CVD risk and all-cause mortality for all six models in the full sample (p<0.001) as well as with increasing quintiles in the restricted sample (eight models) (p<0.001). For CVD risk and all-cause mortality, significantly weaker associations with increasing deciles for models 1 (L·min⁻¹) and 5 (mL·min⁻¹·height⁻²) were seen compared with model 2 (mL·min⁻¹·kg⁻¹), (CVD, p<0.00001; p<0.00001: all-cause mortality, p=0.008; p=0.001) and in some subgroups. For CVD, model 6 (mL·min⁻¹·(kg¹·height⁻¹)⁻¹) had a stronger association compared with model 2 (p<0.00001) and in some subgroups.

In the restricted sample, trends for significantly stronger associations for models including WC compared with model 2 were seen in women for both CVD and all-cause mortality, and those under 50 for CVD.

Conclusion

In association to CVD and all-cause mortality, only small differences were found between ratio scaling and allometric scaling models where body dimensions were added, with some stronger associations when adding WC in the models.

All-Extremity Exercise Training Improves Arterial Stiffness in Older Adults

Large elastic arteries stiffen with age, which predisposes older adults to increased risk for cardiovascular disease. Aerobic exercise training is known to reduce the risk for cardiovascular disease, but the optimal exercise prescription for attenuating large elastic arterial stiffening in older adults is not known.

PURPOSE

The purpose of this randomized controlled trial was to compare the effect of all-extremity high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on aortic pulse wave velocity (PWV) and carotid artery compliance in older adults.

METHODS

Forty-nine sedentary older adults (age = 64 ± 1 yr), free of overt major clinical disease, were randomized to HIIT (n = 17), MICT (n = 18), or nonexercise controls (CONT; n = 14). HIIT (4 × 4 min at 90% HRpeak interspersed with 3 × 3 min active recovery at 70% HRpeak) and isocaloric MICT (70% HRpeak) were performed on an all-extremity non-weight-bearing ergometer, 4 d·wk for 8 wk under supervision. Aortic (carotid to femoral PWV [cfPWV]) and common carotid artery compliance were assessed at pre- and postintervention.

RESULTS

cfPWV improved by 0.5 m·s in MICT (P = 0.04) but did not significantly change in HIIT and CONT (P > 0.05). Carotid artery compliance improved by 0.03 mm·mm Hg in MICT (P = 0.001), but it remained unchanged in HIIT and CONT (P > 0.05). Improvements in arterial stiffness in response to MICT were not confounded by changes in aortic or brachial blood pressure, HR, body weight, total and abdominal adiposity, blood lipids, or aerobic fitness.

CONCLUSION

All-extremity MICT, but not HIIT, improved central arterial stiffness in previously sedentary older adults free of major clinical disease. Our findings have important implications for aerobic exercise prescription in older adults.

Fitness Is Independently Associated with Central Hemodynamics in Metabolic Syndrome

PURPOSE

Fit individuals with metabolic syndrome (MetS) have lower mortality risk compared with less fit counterparts, despite the presence of obesity as a component of the syndrome. To understand the importance of fitness in treating this condition, we examined the association of fitness and fatness with central hemodynamic indices that are known independent predictors of cardiovascular events.

METHODS

Sixty-eight individuals with MetS participated in this cross-sectional study. Central hemodynamics is calculated from radial applanation tonometry and comprised aortic reservoir pressure, backward pressure wave (Pb), reflection magnitude (RM), and augmentation index at 75 bpm (AIx75). Cardiorespiratory fitness (CRF) and body fat percentage (BF%) were determined via indirect calorimetry during maximal exercise testing and dual-energy x-ray absorptiometry, respectively.

RESULTS

CRF was inversely associated with aortic reservoir pressure (r = -0.29, P = 0.02), Pb (r = -0.42, P < 0.001), RM (r = -0.48, P < 0.001), and AIx75 (r = -0.65, P < 0.001). BF% was also correlated with AIx75 (r = 0.37, P < 0.05) and RM (r = 0.36, P < 0.005) but at a weaker association compared with CRF. Multiple regression analysis revealed CRF as a predictor of aortic reservoir pressure (β = -0.52, P = <0.01), Pb (β = -0.41, P < 0.03), and AIx75 (β = -0.45, P = 0.01), independent of BF% and other confounding factors.

CONCLUSIONS

CRF predicts central hemodynamics independent of BF% and other confounding factors. This suggests that CRF improvement may be a higher priority when compared with fat loss for lowering the risk of cardiovascular mortality in MetS individuals.

Combined Association of Cardiorespiratory Fitness and Body Fatness With Cardiometabolic Risk Factors in Older Norwegian Adults: The Generation 100 Study

Objective

To investigate the independent and combined associations of fitness and fatness with cardiometabolic risk factors in older Norwegian women and men.

Patients and Methods

We conducted a cross-sectional study of 505 women and 417 men aged 70 to 77 years enrolled in the Generation 100 study in Norway. Fitness was assessed as peak oxygen uptake and fatness as high body mass index (BMI; ≥25 kg/m²), waist circumference (WC) of 88 cm or greater for women and 102 cm or greater for men, and percent body fat (%BF) of 35% or greater and 25% or greater for women and men, respectively. High cardiometabolic risk was defined as the presence of 2 or more of the following risk factors: elevated triglyceride level, reduced high-density lipoprotein cholesterol concentration, elevated blood pressure, and elevated fasting glucose level or pharmacological treatment of these conditions.

Results

Receiver operating characteristic curve analyses identified fitness levels of less than 25.7 and less than 30.7 mL/kg per minute in women and men, respectively, as critical thresholds for having high cardiometabolic risk. Individuals with levels below these thresholds had an adjusted odds ratio of 2.77 (95% CI, 2.09-3.66) for having high cardiometabolic risk, while high BMI, WC, and %BF had odds ratios (95% CIs) of 3.58 (2.69-4.77), 3.06 (2.29-4.10), and 3.26 (2.47-4.30), respectively. In our combined analyses, being lean did not attenuate the cardiometabolic risk associated with low fitness, and combinations of low fitness and/or high BMI, WC, or %BF cumulatively increased cardiometabolic risk.

Conclusion

Low fitness and indication of fatness were independently and cumulatively associated with poor cardiometabolic health. Our results emphasize the importance of including both physical fitness and body fatness in the assessment of cardiometabolic risk and health promotion efforts in older adults.

What to expect when you're exercising: An experimental test of the anticipated affect-exercise relationship

OBJECTIVE

Anticipated affect may influence exercise behavior via experienced affective responses and intentions. Cognitive manipulations of anticipated affect may inform exercise intervention design. The purpose of this study was to experimentally test the effects of an expectation-based manipulation of affective responses to exercise on anticipated, experienced, and remembered affect and adherence to a 7-day exercise prescription.

METHOD

Participants (N = 98) were randomly assigned to a positive anticipated affect manipulation, a negative anticipated affect manipulation, or a no affect manipulation control. They reported anticipated, experienced, and remembered affect during and after a standardized 30-min bout of treadmill exercise at an intensity just below ventilatory threshold. Participants were asked to try to complete the prescribed exercise daily for 1 week. Differences in affect and exercise behavior were examined across conditions, as were relationships between affect measures, intentions and behavior.

RESULTS

The manipulation influenced anticipated and experienced affective responses, but not behavior. Participants generally expected exercise to be less pleasant and more fatiguing that it actually was. Anticipated, experienced, and remembered affect were associated with intentions to exercise. Intentions and remembered affect were both directly associated with exercise behavior.

CONCLUSIONS

Moderate-to-vigorous exercise can be more pleasant than people expect it to be. Additionally, encouraging exercisers to focus on the positive affective outcomes of exercise can yield a more positive affective experience than those who focus on negative affective outcomes or do not focus on affective outcomes at all. The role of affect in both reflective and automatic motivation to exercise is discussed. (PsycINFO Database Record

Physical Activity and Obesity: Their Interaction and Implications for Disease Risk and the Role of Physical Activity in Healthy Weight Management

The prevalence of overweight and obesity is increasing at an epidemic rate. Increased adiposity, especially central or visceral adiposity, is predictive of cardiovascular disease/coronary heart disease, metabolic syndrome, and type 2 diabetes mellitus. The increased risk for cardiovascular disease/coronary heart disease and metabolic abnormalities associated with abdominal obesity may be mediated, at least in part, by increased systemic inflammation. Greater physical activity and/or fitness may reduce inflammation associated with greater visceral adiposity. Increased adiposity and low levels of physical activity and/or fitness are risk factors for atherosclerotic disease and type 2 diabetes, as well as the increased mortality associated with them. Increased physical activity/fitness reduces disease and mortality risk regardless of body mass index but does not completely abrogate the risks associated with obesity. Both moderate to vigorous physical activity and weight loss independently reduce the risk for type 2 diabetes and improve glucose/insulin metabolism via di ferent mechanisms. Physical activity on the order of 2500 to 2800 kcal/wk may be necessary to prevent weight gain or maintain weight loss. Strength training is recommended as an adjunct to regular aerobic exercise but not as the primary mode of exercise for weight loss. Individuals are strongly encouraged to engage in regular physical activity because of the known health benefits, regardless of whether that activity results in weight loss.

Novel all-extremity high-intensity interval training improves aerobic fitness, cardiac function and insulin resistance in healthy older adults

Aging is associated with decreased aerobic fitness and cardiac remodeling leading to increased risk for cardiovascular disease. High-intensity interval training (HIIT) on the treadmill has been reported to be more effective in ameliorating these risk factors compared with moderate-intensity continuous training (MICT) in patients with cardiometabolic disease. In older adults, however, weight-bearing activities are frequently limited due to musculoskeletal and balance problems. The purpose of this study was to examine the feasibility and safety of non-weight-bearing all-extremity HIIT in older adults. In addition, we tested the hypothesis that all-extremity HIIT will be more effective in improving aerobic fitness, cardiac function, and metabolic risk factors compared with all-extremity MICT. Fifty-one healthy sedentary older adults (age: 65±1years) were randomized to HIIT (n=17), MICT (n=18) or non-exercise control (CONT; n=16). HIIT (4×4min 90% of peak heart rate; HRpeak) and isocaloric MICT (70% of HRpeak) were performed on a non-weight-bearing all-extremity ergometer, 4×/week for 8weeks under supervision. All-extremity HIIT was feasible in older adults and resulted in no adverse events. Aerobic fitness (peak oxygen consumption; VO2peak) and ejection fraction (echocardiography) improved by 11% (P<0.0001) and 4% (P=0.001), respectively in HIIT, while no changes were observed in MICT and CONT (P≥0.1). Greater improvements in ejection fraction were associated with greater improvements in VO2peak (r=0.57; P<0.0001). Insulin resistance (homeostatic model assessment) decreased only in HIIT by 26% (P=0.016). Diastolic function, body composition, glucose and lipids were unaffected (P≥0.1). In conclusion, all-extremity HIIT is feasible and safe in older adults. HIIT, but not MICT, improved aerobic fitness, ejection fraction, and insulin resistance.

Relation of Body's Lean Mass, Fat Mass, and Body Mass Index With Submaximal Systolic Blood Pressure in Young Adult Men

We examined the association of body composition and body mass index (BMI) with submaximal systolic blood pressure (SSBP) among young adult men. The analysis included 211 men with BMI between 20 and 35 kg/m(2). Total lean mass and fat mass were measured using dual x-ray absorptiometry and lean mass percentage was calculated from the total lean mass. Fat mass index (FMI) and BMI were calculated using height and weight (total fat mass and total weight, respectively) measurements. SSBP was measured at each stage of a graded exercise test. Quintiles of lean mass percentage, FMI, and BMI were created with quintile 1 the lowest and quintile 5 the highest lean mass percentage, FMI, and BMI. Compared with men in lean mass percentage quintile 1, those in quintiles 2, 3, and 4 had significantly lower SSBP, whereas there was no significant difference in SSBP between quintile 1 and 5 at 6, 8, and 10 minutes. Compared with men in FMI quintile 5, those in quintiles 2, 3, and 4 had significantly lower SSBP, whereas there was no significant difference in SSBP between quintile 1 and 5. SSBP among men in lean mass percentage quintile 5 and FMI quintile 1 were still less than lean mass percentage quintile 1 and FMI quintile 5, respectively. There were no significant differences in SSBP across BMI quintiles 1 to 4 but a significantly higher SSBP in quintile 5 compared with quintiles 1 to 4. In conclusion, there was a J-curve pattern between SSBP and components of body composition, whereas, a linear relation between SSBP and BMI.

Cardiorespiratory Fitness, Body Fatness, and Submaximal Systolic Blood Pressure Among Young Adult Women

OBJECTIVES

We examined the independent and combined associations of cardiorespiratory fitness (CRF), body fat (BF) percentage (BF%), and body mass index (BMI) with submaximal systolic blood pressure (SSBP) among young adult women.

MATERIALS AND METHODS

Analyses included a sample of 211 normotensive women with a BMI between 20 and 35 kg/m(2); BF% was calculated using total BF measured from dual X-ray absorptiometry, CRF was assessed using a graded exercise test, and SSBP was measured at each stage.

RESULTS

There was a significant direct association of SSBP with BF% and BMI, whereas an inverse association between SSBP and CRF when adjusted for the covariates. There was no significant association between SSBP and BF% across the stages 1-3 with a borderline significant association at stage 4 when further adjusted for CRF, whereas no association at any of the stages when adjusted for BMI. A borderline significant association between SSBP and BMI was found at stage 1 and significant association at stages 2-4 when additionally adjusted for CRF, whereas the association disappeared at stages 1-2 when adjusted for BF%. The inverse association between SSBP and CRF was eliminated at stages 3-4 when further adjusted for BF% with borderline significant association at stages 1-2. The associations remained significant at the stages 1-2 but not at stages 3-4 after adjusting for BMI.

CONCLUSION

CRF, BF%, and BMI seem to have critical roles in determining SSBP with CRF and BF% being more potent at lower intensity exercise, whereas BMI was more strongly associated at higher intensity exercise.

Acute effect of mineralocorticoid receptor antagonism on vascular function in healthy older adults

Mineralocorticoid receptor (MR) activation by aldosterone may regulate vascular function in health or contribute to vascular dysfunction in cardiovascular disease. Whether the effects are beneficial or detrimental to vascular function appear to be dependent on the integrity of the vascular endothelium and whether the responses are short-term or chronic. Acute modulation of MR activation has resulted in conflicting outcomes on vascular function in young healthy adults. Little is known about the vascular role of aldosterone and MR activation in healthy human aging. The primary objective of this study was to examine whether acute inhibition of MR by the selective antagonist eplerenone, influences vascular function in healthy older adults. We performed a randomized, double-blind, placebo-controlled crossover study in 22 adults (61±1 years; mean±SE, 53-79 years) who were free from overt clinical cardiovascular disease. We measured brachial artery flow-mediated endothelium-dependent dilation and endothelium-independent dilation to sublingual nitroglycerin (0.4 mg) following eplerenone (100 mg/dose, 2 doses, 24h between doses) or placebo. In response to acute MR antagonism, flow-mediated dilation decreased by 19% (from 6.9±0.5 to 5.6±0.6%, P=0.02; placebo vs. eplerenone). Endothelial nitric oxide synthase (eNOS) activity also decreased following MR antagonism based on the ratio of phosphorylated eNOS(Ser1177) to total eNOS (1.53±0.08 vs. 1.29±0.06, P=0.02). Nitroglycerin-induced dilation and blood pressure were unaffected (nitroglycerin-induced dilation: 21.9±1.9 vs. 21.0±1.5%, P=0.5 and systolic/diastolic blood pressure: 135/77±4/2 vs. 134/77±4/2 mmHg, P≥0.6). In conclusion, acute MR antagonism impairs vascular endothelial function in healthy older adults without influencing vascular smooth muscle responsiveness to exogenous nitric oxide or blood pressure.

The contribution of childhood cardiorespiratory fitness and adiposity to inflammation in young adults

OBJECTIVE

Cardiorespiratory fitness and adiposity may influence cardiovascular risk through their effects on inflammation. The long-term effects of these modifiable factors on adult inflammation remain uncertain. The associations of childhood and adulthood cardiorespiratory fitness and adiposity with adult inflammation [C-reactive protein (CRP), fibrinogen] were examined.

METHODS

1,976 children examined in 1985 and re-examined as young adults in 2004-2006 were included. Cardiorespiratory fitness and adiposity were assessed at both waves. CRP and fibrinogen were measured at follow-up.

RESULTS

Higher childhood fitness was associated with lower adult inflammation in both sexes. After adjusting for childhood adiposity, the association with CRP attenuated in males, but remained in females (average reduction of CRP 18.1% (95% CI 11.3-24.4%) per 1-SD increase in childhood fitness). Higher adult fitness, adjusting for childhood fitness (an increase in fitness from childhood to adulthood), was associated with lower adult CRP in females and lower fibrinogen in males. Higher childhood and adulthood adiposity (an increase in adiposity from childhood to adulthood) were associated with higher adult inflammation in both sexes.

CONCLUSIONS

Prevention programs to increase fitness and reduce adiposity in childhood, and maintain a favorable fitness and weight into adulthood, may lead to reduction in adult systemic inflammation.

Cardiorespiratory Fitness is a Strong Predictor of the Cardio-ankle Vascular Index in Hypertensive Middle-aged and Elderly Japanese Men

AIM

This study aimed to examine whether cardiorespiratory fitness (CRF) is associated with arterial stiffening, evaluated using the cardio-ankle vascular index (CAVI), independent of visceral fat (VF) in middle-aged and elderly Japanese men. We also examined whether the relationship between CRF and the CAVI is modified by age and/or hypertension.

METHODS

The CAVI was determined in 157 Japanese men (age range, 30-79 years), including 96 hypertensive subjects (61.1%). CRF was assessed by measuring the peak oxygen uptake (VO2peak). The subjects were divided into low- and high-CRF groups, and the VF area was assessed using magnetic resonance imaging.

RESULTS

The VO2peak correlated with the CAVI following adjustment for age and body mass index in the middle-aged and elderly groups (all the subjects: r=-0.285, p＜0.001; middle-aged: r=-0.240, p=0.040; elderly: r=-0.225, p=0.049). VF also correlated with the CAVI (r=0.230, p=0.004). A multiple linear regression analysis revealed that age (β=0.406, p<0.001) and the VO2peak (β=-0.186, p=0.015) were associated with the CAVI independently of VF and the mean blood pressure. Two way ANCOVA adjusted for age demonstrated that the hypertensive individuals had higher CAVI values than the normotensive individuals in the low-CRF group, whereas no significant differences in the CAVI were observed in the high-CRF group (p for interaction <0.05).

CONCLUSIONS

In the present study, CRF was found to be associated with the CAVI, independent of age and VF, in hypertensive middle-aged and elderly Japanese men.

Physical activity and differential methylation of breast cancer genes assayed from saliva: a preliminary investigation

PURPOSE

Individuals who exercise are at lower risk for breast cancer and have better post-diagnosis outcomes. The biological mechanisms behind this association are unclear, but DNA methylation has been suggested.

METHODS

We developed a composite measure of DNA methylation across 45 CpG sites on genes selected a priori. We examined the association of this measure to self-reported physical activity and objectively measured cardiovascular fitness in a sample of healthy nonsmoking adults (n = 64) in an exercise promotion intervention.

RESULTS

Individuals who were more physically fit and who exercised more minutes per week had lower levels of DNA methylation. Those who increased their minutes of physical activity over 12 months experienced decreases in DNA methylation.

CONCLUSIONS

DNA methylation may be a mechanism linking exercise and cancer incidence and could serve as a biomarker for behavioral intervention trials. Studies with larger samples, objectively measured exercise, and more cancer-related markers are needed.

Colorado stride (COSTRIDE): testing genetic and physiological moderators of response to an intervention to increase physical activity

BACKGROUND

The purpose of this research was to replicate a successful intervention to increase physical activity in a different region of the country, and explore genetic and physiological moderators of intervention efficacy drawn from a transdisciplinary theoretical framework.

METHOD

A randomized controlled trial comparing a print-based physical activity intervention (COSTRIDE) to a print-based health and wellness contact control (HW) intervention was conducted. Sedentary participants (n = 219) completed assessments at baseline and follow-up assessments at 3, 6, 9, and 12 months following the initiation of the intervention.

RESULTS

Participants in both conditions significantly increased exercise behavior in the first six months, and then leveled off or decreased physical activity in the second six months of the study. Those in the COSTRIDE intervention increased significantly more than those in the HW intervention, and were better able to maintain their exercise behavior. Genetic factors (BDNF, rs6265; FTO, rs8044769), but not selected physiological (body temperature, blood lactate, systolic blood pressure, plasma norepinephrine, and heart rate) or subjective (perceived pain, affect) responses to physical activity, moderated response to the intervention.

CONCLUSIONS

There are underlying genetic factors that influence response to behavioral intervention, and a better understanding of these factors has the potential to influence the development, targeting and tailoring of behavioral interventions to increase physical activity.

TRIAL REGISTRATION

Clinicaltrials.gov registration: NCT01091857.

The prevalence of metabolic syndrome and metabolic syndrome risk factors in college-aged students

PURPOSE

Metabolic syndrome (MetS) is characterized by a constellation of metabolic risk factors that consist of the following: atherogenic dyslipidemia, elevated blood pressure, elevated glucose associated with insulin resistance, prothrombotic state, and proinflammatory state. The objective of the study was to quantify the prevalence of MetS among college students and to determine whether fatness (body mass index [BMI] and waist circumference) or physical activity was more strongly associated with individual components of the MetS.

DESIGN

A cross-sectional study.

SETTING

Eau Claire, Wisconsin, United States.

SUBJECTS

Authors collected health history information and performed assessments of individual MetS components for 207 college students aged 18 to 24 years.

MEASURES

Physical activity levels were self-reported, while direct measurements were obtained for MetS components (waist circumference, blood pressure, high-density lipoprotein (HDL)-cholesterol, triglycerides, blood glucose).

ANALYSIS

Descriptive statistics and multiple regression analysis.

RESULTS

The prevalence of MetS was found to be 6.8% according to the National Cholesterol Education Program Adult Treatment Panel III guidelines. The authors also found that 42.5% and 13.0% of our sample had one and two MetS components, respectively. Waist circumference was independently associated (p < .05) with HDL-cholesterol, triglycerides, and systolic blood pressure.

CONCLUSION

Our findings provide evidence for the presence of MetS on college campuses. It also appears, in part, that central adiposity contributes to the high incidence of individual MetS components. Given the elevated lifetime risk for cardiovascular disease and lower survival for those with risk factors in young adulthood, there appears to be a need for primary prevention programs within university and college settings.

Mineralocorticoid receptors modulate vascular endothelial function in human obesity

Obesity increases linearly with age and is associated with impaired vascular endothelial function and increased risk of cardiovascular disease. MRs (mineralocorticoid receptors) contribute to impaired vascular endothelial function in cardiovascular disease; however, their role in uncomplicated human obesity is unknown. Because plasma aldosterone levels are elevated in obesity and adipocytes may be a source of aldosterone, we hypothesized that MRs modulate vascular endothelial function in older adults in an adiposity-dependent manner. To test this hypothesis, we administered MR blockade (eplerenone; 100 mg/day) for 1 month in a balanced randomized double-blind placebo-controlled cross-over study to 22 older adults (ten men, 55-79 years) varying widely in adiposity [BMI (body mass index): 20-45 kg/m²], but who were free from overt cardiovascular disease. We evaluated vascular endothelial function [brachial artery FMD (flow-mediated dilation)] via ultrasonography) and oxidative stress (plasma F2-isoprostanes and vascular endothelial cell protein expression of nitrotyrosine and NADPH oxidase p47phox) during placebo and MR blockade. In the whole group, oxidative stress (P>0.05) and FMD did not change with MR blockade (6.39 ± 0.67 compared with 6.23 ± 0.73%; P=0.7). However, individual improvements in FMD in response to eplerenone were associated with higher total body fat (BMI: r=0.45, P=0.02; and dual-energy X-ray absorptiometry-derived percentage body fat: r=0.50, P=0.009) and abdominal fat (total: r=0.61, P=0.005; visceral: r=0.67, P=0.002; and subcutaneous: r=0.48, P=0.03). In addition, greater improvements in FMD with eplerenone were related to higher baseline fasting glucose (r=0.53, P=0.01). MRs influence vascular endothelial function in an adiposity-dependent manner in healthy older adults.

Cardiorespiratory fitness and adiposity in metabolically healthy overweight and obese youth

OBJECTIVE

Controversy exists surrounding the contribution of fitness and adiposity as determinants of the Metabolically Healthy Overweight(MHO) phenotype in youth. This study investigated the independent contribution of cardiorespiratory fitness and adiposity to the MHO phenotype among overweight and obese youth.

METHODS

This cross-sectional study included 108 overweight and obese youth classified as MHO (no cardiometabolic risk factors) or non-MHO (≥1 cardiometabolic risk factor), based on age- and gender specific cut-points for fasting glucose, triglycerides, high-density lipoprotein cholesterol, systolic and diastolic blood pressure, and hepaticsteatosis.

RESULTS

Twenty-five percent of overweight and obese youth were classified as MHO. This phenotype was associated with lower BMIz-score (BMI z-score: 1.8 ± 0.3 vs 2.1 ± 0.4, P = .02) and waist circumference (99.7 ± 13.2 vs 106.1 ± 13.7 cm, P = .04) compared with non-MHO youth. When matched for fitness level and stratified by BMI z-score (1.6 ± 0.3 vs 2.4 ± 0.2), the prevalence of MHO was four fold higher in the low BMI z-score group (27% vs 7%; P = .03).Multiple logistic regression analyses revealed that the best predictor of MHO was the absence of hepatic steatosis even after adjusting for waist circumference (odds ratio 0.57, 95% confidence interval 0.40–0.80) or BMI z-score (odds ratio 0.59, 95% confidence interval 0.43–0.80).

CONCLUSIONS

The MHO phenotype was present in 25% of overweight and obese youth and is strongly associated with lower levels of adiposity,and the absence of hepatic steatosis, but not with cardiorespiratory fitness.

Role of mineralocorticoid receptors in arterial stiffness in human aging

Arterial stiffness, an independent predictor of cardiovascular disease, is increased in aging, but the underlying mechanisms are not completely understood. Mineralocorticoid receptors (MR) may contribute to oxidative stress and arterial stiffness in healthy older adults. To test the hypothesis that short-term MR blockade may reduce oxidative stress and improve arterial stiffness, we conducted a randomized, double blind, crossover study using the selective MR blocker Eplerenone or placebo in 23 older adults (age, 64±1 years; mean±SE) free from overt cardiovascular and other clinical disease (e.g, diabetes, renal and liver disease). In response to MR blockade, brachial and carotid blood pressure decreased (P≤0.01). However, MR blockade had no effect on oxidative stress (oxidized LDL, 61.2±6.8 vs. 62.4±7.4 U/L, P=0.9; placebo vs. Eplerenone) and arterial stiffness (aortic pulse wave velocity (PWV), 9.17±1.19 vs. 8.92±1.19 m/s, P=0.5; leg PWV, 13.45±0.45 vs. 12.81±0.47 m/s, P=0.3; arm PWV, 11.43±0.62 vs. 11.73±0.68 m/s, P=0.7; carotid artery compliance, 0.150±0.013 vs. 0.149±0.014 mm(2)/mmHg, P=0.8; distensibility, 23.1±1.8 vs. 23.3±1.7 10(-3)/kPa, P=0.8; β stiffness index, 3.5±0.3 vs. 3.6±0.3, P=0.6; and augmentation index, 16.0±2.2 vs. 15.6±2.8%, P=0.8). These results provide the first evidence that MR do not appear to contribute to oxidative stress in human aging and that short-term MR blockade does not result in reduced oxidative stress and improved arterial stiffness.

Impact of fitness versus obesity on routinely measured cardiometabolic risk in young, healthy adults

Obesity demonstrates a direct relation with cardiovascular risk and all-cause mortality, while cardiorespiratory fitness demonstrates an inverse relation. In clinical practice, several cardiometabolic (CM) risk factors are commonly measured to gauge cardiovascular risk, but the interaction between fitness and obesity with regard to CM risk has not been fully explored. In this study, 2,634 Brazilian adults referred for employer-sponsored heath exams were assessed. Obesity was defined as body mass index >30 kg/m(2) or waist circumference >102 cm in men or >88 cm in women when body mass index was 25 to 30 kg/m(2). Fitness was quantified by stage achieved on an Ellestad treadmill stress test, with those completing stage 4 considered fit. Hepatic steatosis was determined by ultrasound. CM risk factors were compared after stratifying patients into 4 groups: fit and normal weight, fit and obese, unfit and normal weight, and unfit and obese. Approximately 22% of patients were obese; 12% were unfit. Fitness and obesity were moderately correlated (ρ = 0.38 to 0.50). The sample included 6.5% unfit and normal-weight subjects and 16% fit and obese subjects. In overweight and obese patients, fitness was negatively associated with CM risk (p <0.01 for all values). In fit patients, increasing body mass index was positively associated with CM risk (p <0.01 for all values). In instances of discordance between fitness and obesity, obesity was the stronger determinant of CM risk. In conclusion, fitness and obesity are independently associated with CM risk. The effects of fitness and obesity are additive, but obesity is more strongly associated with CM risk when fitness and obesity are discordant. These findings underscore the need for weight loss in obese patients and suggest an unmeasured benefit of fitness.

A transdisciplinary approach to the selection of moderators of an exercise promotion intervention: baseline data and rationale for Colorado STRIDE

A transdisciplinary approach incorporating biological, psychological, behavioral, and genetic factors was taken to better identify proposed moderators of the effectiveness of an intervention to increase physical activity. This paper illustrates how theory-based individual difference variables can be integrated into a complex randomized controlled trial. The transdisciplinary framework guiding the selection of moderators, the COSTRIDE intervention study and sample, and the relationships among baseline variables are provided. Participants were non-active individuals randomly assigned to either the STRIDE exercise or health-and-wellness contact control condition. Structural equation modeling was utilized to demonstrate that relationships among baseline variables confirm hypothesized relationships in the transdisciplinary framework. Preliminary data from COSTRIDE suggest that interventions among sedentary individuals may be more effective if a broader range of factors influencing physical activity are considered.

Effects of current physical activity on affective response to exercise: physical and social-cognitive mechanisms

Affective responses during exercise are often important determinants of exercise initiation and maintenance. Current physical activity may be one individual difference that is associated with the degree to which individuals have positive (or negative) affective experiences during exercise. The objective of this study was to explore physical and cognitive explanations of the relationship between current activity status (more versus less active) and affective response during a 30-minute bout of moderate-intensity exercise. Participants reported their current level of physical activity, exercise self-efficacy and affect during a 30-minute bout of moderate-intensity exercise. More active individuals experienced higher levels of positive affect and tranquillity and lower levels of negative affect and fatigue during exercise. Multivariate models for each affective state indicated separate processes through which physical activity may be associated with changes in affect during exercise. These models indicate that affect experienced during physical activity is related to the current activity level and these relationships can be partially explained by the physical and cognitive factors explored in this study. Recommendations for future research to elucidate whether positive affective response to physical activity improves as a function of becoming more active over time are discussed.

Vascular smooth muscle responsiveness to nitric oxide is reduced in healthy adults with increased adiposity

Vascular smooth muscle responsiveness to nitric oxide, as assessed by nitroglycerin-induced dilation (NID), is impaired in clinical cardiovascular disease, but its relation to adiposity is unknown. We determined the relation of NID to total and abdominal adiposity in healthy adults varying widely in adiposity. In 224 men and women [age, 18-79 years; body mass index (BMI), 16.4-42.2 kg/m(2)], we measured NID (brachial artery dilation to 0.4 mg sublingual nitroglycerin), total body adiposity [BMI and percent body fat (percent BF via dual-energy X-ray absorptiometry)], and indexes of abdominal adiposity [waist circumference (WC) and waist-to-hip ratio (WHR)]. In a subgroup (n = 74), we also measured total abdominal fat (TAF), abdominal visceral fat (AVF), and subcutaneous fat (ASF) using computed tomography. Based on multiple linear regression, NID was negatively related to BMI [part correlation coefficient (r(part)) = -0.19, P = 0.004] and abdominal adiposity (WC, r(part) = -0.22; WHR, r(part) = -0.19; TAF, r(part) = -0.36; AVF, r(part) = -0.36; and ASF, r(part) = -0.30; all P ≤ 0.009) independent of sex, but only tended to be related to total percent BF (r(part) = -0.12, P = 0.07). In a subgroup of subjects with the highest compared with the lowest amount of AVF, NID was 35% lower (P = 0.003). Accounting for systolic blood pressure, HDL cholesterol, glucose, insulin resistance, adiponectin, and brachial artery diameter reduced or abolished some of the relations between NID and adiposity. In conclusion, NID is or tends to be negatively associated with measures of total adiposity (BMI and percent BF, respectively) but is consistently and more strongly negatively associated with abdominal adiposity. Adiposity may influence NID in part via other cardiovascular risk factors.

Genetic Influences on Physiological and Subjective Responses to an Aerobic Exercise Session among Sedentary Adults

Objective. To determine whether genetic variants suggested by the literature to be associated with physiology and fitness phenotypes predicted differential physiological and subjective responses to a bout of aerobic exercise among inactive but otherwise healthy adults. Method. Participants completed a 30-minute submaximal aerobic exercise session. Measures of physiological and subjective responding were taken before, during, and after exercise. 14 single nucleotide polymorphisms (SNPs) that have been previously associated with various exercise phenotypes were tested for associations with physiological and subjective response to exercise phenotypes. Results. We found that two SNPs in the FTO gene (rs8044769 and rs3751812) were related to positive affect change during exercise. Two SNPs in the CREB1 gene (rs2253206 and 2360969) were related to change in temperature during exercise and with maximal oxygen capacity (VO(2) max). The SLIT2 SNP rs1379659 and the FAM5C SNP rs1935881 were associated with norepinephrine change during exercise. Finally, the OPRM1 SNP rs1799971 was related to changes in norepinephrine, lactate, and rate of perceived exertion (RPE) during exercise. Conclusion. Genetic factors influence both physiological and subjective responses to exercise. A better understanding of genetic factors underlying physiological and subjective responses to aerobic exercise has implications for development and potential tailoring of exercise interventions.

Cognitive and neural correlates of aerobic fitness in obese older adults

BacKGROUND/STUDY CONTEXT: Aerobic fitness is associated with preserved cognition and brain volume in older adulthood. The current study investigated whether the benefits of aerobic fitness extend to obese older adults, a segment of the population that is rapidly growing and who exhibit compromised cognition and brain structure relative to their nonobese counterparts.

METHODS

Measures of obesity, aerobic fitness, cognition (processing speed, executive function, spatial ability, memory), and regional brain volumes (prefrontal gray, prefrontal white, hippocampus) were obtained from 19 obese older adults aged 65 to 75. Hierarchical linear regression analyses were conducted to examine the proportion of unique variance in cognitive and volumetric measures accounted for by aerobic fitness after controlling for covariates (age, gender, and waist circumference).

RESULTS

Aerobic fitness accounted for a significant amount of unique variance in processing speed (adjusted R (2) = .44), executive function (adjusted R (2) = .34), and hippocampal volume (adjusted R (2) = .27).

CONCLUSION

This novel pattern of results suggests that obesity does not preclude the benefits of fitness for cognition and brain volume in older adults. Fitness appears to be a beneficial factor for maintenance of processing speed, executive function, and hippocampal volume, which are vulnerable to age- and/or obesity-related decline.

Changes in fitness and fatness on the development of cardiovascular disease risk factors hypertension, metabolic syndrome, and hypercholesterolemia

OBJECTIVES

This study sought examine the independent and combined associations of changes in fitness and fatness with the subsequent incidence of the cardiovascular disease (CVD) risk factors of hypertension, metabolic syndrome, and hypercholesterolemia.

BACKGROUND

The relative and combined contributions of fitness and fatness to health are controversial, and few studies are available on the associations of changes in fitness and fatness with the development of CVD risk factors.

METHODS

We followed up 3,148 healthy adults who received at least 3 medical examinations. Fitness was determined by using a maximal treadmill test. Fatness was expressed by percent body fat and body mass index. Changes in fitness and fatness between the first and second examinations were categorized into loss, stable, or gain groups.

RESULTS

During the 6-year follow-up after the second examination, 752, 426, and 597 adults developed hypertension, metabolic syndrome, and hypercholesterolemia, respectively. Maintaining or improving fitness was associated with lower risk of developing each outcome, whereas increasing fatness was associated with higher risk of developing each outcome, after adjusting for possible confounders and fatness or fitness for each other (all p for trend <0.05). In the joint analyses, the increased risks associated with fat gain appeared to be attenuated, although not completely eliminated, when fitness was maintained or improved. In addition, the increased risks associated with fitness loss were also somewhat attenuated when fatness was reduced.

CONCLUSIONS

Both maintaining or improving fitness and preventing fat gain are important to reduce the risk of developing CVD risk factors in healthy adults.

Physical fitness is independently related to blood leptin concentration and insulin sensitivity index in male subjects with central adiposity

AIM

To compare the maximal power output (MPO) of subjects presenting a central adiposity to those of controls and to study the links between plasma leptin or indices of insulin sensitivity (QUICKI) and physical fitness (PF).

METHODS

MPO was determined for 169 middle-aged men divided into two groups according to waist circumference (WC- < 94 cm, WC+ ≥ 94 cm) each subdivided in two subgroups with low and high PF (WC-L, WC-H, WC+L, WC+H) determined from the median MPO relative to fat free mass (3.06 W/kg(FFM)).

RESULTS

MPO (W/kg(FFM)) was lower in WC+ than in WC-. Expressed relative to fat mass, leptin was lower and QUICKI higher in WC- than in WC+. In WC+H, leptin and QUICKI were significantly less disturbed than in WC+L and were independently correlated to MPO (r = -0.36 and r = 0.32 respectively; p < 0.001). In WC+, when visceral perimeter was added to the analysis, the relationships MPO/leptin remained significant but not MPO/QUICKI.

CONCLUSION

The low PF in subjects with abdominal obesity is independently linked to plasma leptin and insulin sensitivity even if leptin and insulin may share common pathways in their peripheral effects. Visceral adiposity participates to the link between MPO and QUICKI, but not between MPO and leptin.

Habitually exercising older men do not demonstrate age-associated vascular endothelial oxidative stress

We tested the hypothesis that older men who perform habitual aerobic exercise do not demonstrate age-associated vascular endothelial oxidative stress compared with their sedentary peers. Older exercising men (n=13, 62±2 years) had higher (P<0.05) physical activity (79±7 vs. 30±6 MET hours per week) and maximal exercise oxygen consumption (42±1 vs. 29±1 mL kg(-1) per minute) vs. sedentary men (n=28, 63±1 years). Brachial artery flow-mediated dilation (FMD), a measure of vascular endothelial function, was greater (P<0.05) in the exercising vs. sedentary older men (6.3±0.5 vs. 4.9±0.4%Δ) and not different than young controls (n=20, 25±1 years, 7.1±0.5%Δ). In vascular endothelial cells sampled from the brachial artery, nitrotyrosine, a marker of oxidative stress, was 51% lower in the exercising vs. sedentary older men (0.38±0.06 vs. 0.77±0.10 AU). This was associated with lower endothelial expression of the oxidant enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (p47(phox) subunit, 0.33±0.05 vs. 0.61±0.09 AU) and the redox-sensitive transcription factor nuclear factor kappa B (NFκB) (p65 subunit, 0.36±0.05 vs. 0.72±0.09 AU). Expression of the antioxidant enzyme manganese superoxide dismutase (SOD) (0.57±0.13 vs. 0.30±0.04 AU) and activity of endothelium-bound extracellular SOD were greater (6.4±0.5 vs. 5.0±0.6 U mL(-1) per minute) in the exercising men (both P<0.05), but differences no longer were significant after correcting for adiposity and circulating metabolic factors. Overall, values for the young controls differed with those for the sedentary, but not the exercising older men. Older men who exercise regularly do not demonstrate vascular endothelial oxidative stress, and this may be a key molecular mechanism underlying their reduced risk of cardiovascular diseases.

Screening for insulin resistance and cardiovascular risk in collegiate football linemen

OBJECTIVE

To investigate the relationship between fitness, obesity, and the risk factors of type 2 diabetes and cardiovascular disease in obese-classified [by body mass index (BMI) > 30 kg/m] collegiate football linemen and male students of similar age and BMI.

DESIGN

Cross-sectional observational study.

SETTING

Institutional university based.

PARTICIPANTS

Two groups of volunteer students. Thirty collegiate football linemen and 10 sedentary age-matched and size-matched peers.

INDEPENDENT VARIABLE

Status as lineman or sedentary student.

MAIN OUTCOME MEASURES

Height, weight, blood pressure, and body fat percent (BF%) were measured for each subject. Fasting blood draw was used to determine glucose, insulin, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides.

RESULTS

The athlete group had lower mean (SD) BF% [21.8 (3.89) vs control 27.1 (7.07); P = 0.01], despite no significant difference in age, weight, height, or BMI. The athlete group had lower systolic blood pressure [135.6 (13.29) mm Hg vs 148.1 (13.77); P = 0.015] and at-risk LDL (10% vs 40%; P = 0.05). The groups did not differ significantly in other measures. Body fat percent (before and after adjusting for BMI) was significantly correlated with every risk factor except glucose, whereas BMI was only significantly correlated with blood pressure and insulin.

CONCLUSIONS

Collegiate football linemen with elevated BMI have select risk factors, particularly blood pressure and LDL cholesterol that improved over sedentary peers. However, concerning risk factor profiles of linemen warrant standard age-appropriate and size-appropriate screening for cardiovascular and metabolic disease. Body fat percent more strongly correlated with risk factors than with BMI and may be the stronger tool for estimating risk in this population.

Menstrual cycle effects on perceived exertion and pain during exercise among sedentary women

BACKGROUND

Increasing cardiovascular fitness through exercise participation among sedentary people is important for decreasing all-cause mortality. From an intervention perspective, identifying modifiable factors that maximize the successful initiation of exercise is of utmost importance. For women, cyclic hormonal variations can influence aspects of health and health behaviors, from smoking cessation efficacy to physiological responses to exercise. The purpose of this study was to examine the influence of menstrual cycle phase and hormonal contraceptive (HC) use on subjective response to an initial bout of moderate intensity exercise among previously sedentary women (n = 117).

METHODS

Women completed a treadmill exercise challenge session at 65% of their previously determined maximum oxygen consumption (Vo(2) max) during the early follicular, late follicular, or luteal phase. Participants reported ratings of perceived exertion and pain using Borg's Rating of Perceived Exertion (RPE) and CR10 scales at 10, 20, and 30 minutes during the exercise session.

RESULTS

There was a significant menstrual phase x birth control interaction on change in RPE [F(2, 111) = 3.75, p < 0.05] and change in perceived pain [F(2, 110) = 3.31, p < 0.05]. Women in the early follicular phase who were not using HCs had significantly greater increases in RPE and increases in pain compared with women in the late follicular and luteal phases.

CONCLUSIONS

Our results indicate that the use of HC and cycle phase influence sedentary women's subjective response to exercise. These results have important implications for the timing of exercise interventions aimed at increasing exercise among sedentary women.

The Big Picture of Individual Differences in Physical Activity Behavior Change: A Transdisciplinary Approach

The goal of this research is to utilize a transdisciplinary framework to guide the selection of putative moderators of the effectiveness of an intervention to promote physical activity behavior adoption and maintenance in the context of a randomized controlled intervention trial. Effective interventions to increase physical activity are sorely needed, and one barrier to the identification and development of such interventions is the lack of research targeted at understanding both the mechanisms of intervention efficacy and for whom particular interventions are effective. The purpose of this paper is to outline our transdisciplinary approach to understanding individual differences in the effectiveness of a previously successful exercise promotion intervention. We explain the rationale for and operationalization of our framework, characteristics of the study to which we apply the framework, and planned analyses. By embracing a transdisciplinary orientation for individual differences important in the prediction of physical activity (spanning molecular approaches, animal models, human laboratory models, and social psychological models), we hope to have a better understanding of characteristics of individuals that are important in the adoption and maintenance of physical activity.

Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism

Over the last decade, investigators have given increased attention to the effects of resistance training (RT) on several metabolic syndrome variables. The metabolic consequences of reduced muscle mass, as a result of normal aging or decreased physical activity, lead to a high prevalence of metabolic disorders. The purpose of this review is: (i) to perform a meta-analysis of randomized controlled trials (RCTs) regarding the effect of RT on obesity-related impaired glucose tolerance and type 2 diabetes mellitus; and (ii) to investigate the existence of a dose-response relationship between intensity, duration and frequency of RT and the metabolic clustering. Thirteen RCTs were identified through a systematic literature search in MEDLINE ranging from January 1990 to September 2007. We included all RCTs comparing RT with a control group in patients with abnormal glucose regulation. For data analysis, we performed random effects meta-analyses to determine weighted mean differences (WMD) with 95% confidence intervals (CIs) for each endpoint. All data were analysed with the software package Review Manager 4.2.10 of the Cochrane Collaboration. In the 13 RCTs included in our analysis, RT reduced glycosylated haemoglobin (HbA(1c)) by 0.48% (95% CI -0.76, -0.21; p = 0.0005), fat mass by 2.33 kg (95% CI -4.71, 0.04; p = 0.05) and systolic blood pressure by 6.19 mmHg (95% CI 1.00, 11.38; p = 0.02). There was no statistically significant effect of RT on total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride and diastolic blood pressure. Based on our meta-analysis, RT has a clinically and statistically significant effect on metabolic syndrome risk factors such as obesity, HbA(1c) levels and systolic blood pressure, and therefore should be recommended in the management of type 2 diabetes and metabolic disorders.

The "fit but fat" concept revisited: population-based estimates using NHANES

Low cardiovascular fitness is an independent risk factor for type 2 diabetes and cardiovascular disease in adults. The "fit but fat" concept suggests that cardiovascular fitness attenuates risk of metabolic and cardiovascular disease independent of body mass index (BMI), even among the obese. However, the proportion of U.S. adults considered both fit and obese is unknown. Thus, the purposes of this short paper were to estimate the proportion of U.S. adults who are obese yet have a high cardiovascular fitness level (fit but fat), and determine the independent effect of obesity on cardiovascular fitness. The study was a secondary data analysis of 4,675 adults (20-49 years) who completed a submaximal exercise test, from the National Health and Nutrition Examination Survey (1999-2002). Cardiovascular fitness and body weight were expressed as continuous (estimated VO_2max [ml.kg^-1.min^-1] and BMI [kg/m²]) and categorical variables (low, moderate, and high cardiovascular fitness level; normal weight, overweight, and obese), the later using sex and age-specific criteria from the Aerobics Center Longitudinal Study and standard BMI cut-points, respectively. Using these methods, the prevalence of meeting the fit but fat definition among U.S. adults was 8.9% (95% C.I. = 6.9 - 10.9%), whereas 17.4% were overweight and high fit, and 30% were normal weight and high fit. Importantly, the proportion of low, moderate, and high cardiovascular fitness differed significantly (p < 0.05) by BMI level. Using multiple regression, being obese was associated with a 9.2% lower estimated VO_2max compared to being normal weight, even after controlling for age, sex, race/ethnicity, and income. These results suggest that a small percentage of U.S. adults can be considered fit but fat, and that obesity is independently associated with reduced cardiovascular fitness. The likely explanation for the low proportion of U.S. adults who can be considered fit but fat is a low level of physical activity, which constributes to both a positive energy balance and low fitness. Thus, engaging obese adults in physical activity that is sufficient to improve cardiovascular fitness may help to reduce not only body weight, but the excess health burden in this population.

Adiposity, physical activity and blood lipid profile in 13-year-old adolescents

The main aim of this study was to determine the extent to which physical activity and adiposity are associated with blood cholesterol levels in male adolescents. Anthropometric and physical fitness values were measured in all children. Body mass index (BMI) and physical activity index (PAI) were used to split participants into active overweight (ACO) and non-active normal-weight (NAN) groups. The cutoffs for the ACO group were BMI > or = 22.6 kg/m2 and PAI > or = 3.5, respectively, whereas the corresponding cutoffs for the NAN groups were BMI < 20.0 kg/m2 and PAI < 2. A total of 65 children (29 in ACO group, 36 in NAN group) were selected according to the above criteria. ACO group showed significantly higher BMI and body fat as compared to their NAN counterparts (p < 0.05). Adolescents from ACO group attained superior scores for PAI and aerobic fitness (p < 0.05). Most blood lipid variables were significantly lower in ACO group as compared to NAN (p < 0.05) while HDL-cholesterol was higher in ACO group (p < 0.05). There was significant positive correlation between HDL-cholesterol and PAI in ACO group (r = 0.38; p < 0.05). The physical activity index explained the majority of variance in HDL-cholesterol for ACO group (beta = 0.513; p < 0.05). It seems that physical activity in adolescents is a more important factor in balancing blood lipid status than adiposity per se, particularly for HDL-cholesterol.