Influence of cardiorespiratory fitness and body composition on resting and post-exercise indices of vascular health in young adults

Poor cardiorespiratory fitness may mediate vascular impairments at rest and following an acute bout of exercise in young healthy individuals. This study aimed to compare flow mediated dilation (FMD) and vascular augmentation index (AIx75) between young adults with low, moderate, and high levels of cardiorespiratory fitness before and after an acute bout of aerobic exercise. Forty-three participants (22 men; 21 women) between 18 and 29 years of age completed the study. Participants were classified into low, moderate, and high health-related cardiorespiratory fitness groups according to age- and sex-based relative maximal oxygen consumption (V ˙ O2 max) percentile rankings. FMD was performed using Doppler ultrasound and AIx75 was performed using pulse wave analysis at baseline and 60-min after a 30-min bout of treadmill running at 70% V ˙ O2 max. A significant interaction (p ​= ​0.047; ηp2 ​= ​0.142) was observed, with the moderate fitness group exhibiting a higher FMD post-exercise compared with baseline ([6.7% ​± ​3.1%] vs. [8.5% ​± ​2.8%], p ​= ​0.028; d ​= ​0.598). We found a significant main effect of group for AIx75 (p ​= ​0.023; ηp2 ​= ​0.168), with the high fitness group exhibiting lower AIx75 compared to low fitness group ([-10% ​± ​10%] vs. [2% ​± ​10%], respectively, p ​= ​0.019; g ​= ​1.07). This was eliminated after covarying for body fat percentage (p ​= ​0.489). Our findings suggest that resting FMD and AIx75 responses are not significantly influenced by cardiorespiratory fitness, but FMD recovery responses to exercise may be enhanced in individuals with moderate cardiorespiratory fitness levels.

The effects of an exercise intervention on executive function among overweight adults with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is associated with poorer executive function. This study examined the effects of a comprehensive exercise intervention on executive function in overweight adults with mild and moderate-to-severe OSA.

METHODS

Participants aged between 30 and 65 years, with a body mass index (BMI) ranging from 27 to 42 kg/m^2, participated in a 6-week exercise program. Standardized polysomnographic recording methods provided total Apnea-Hypopnea Index (AHI) and level of hypoxemia. Executive function was assessed using the NIH Toolbox Flanker Inhibitory Control Test. A submaximal treadmill exercise test evaluated cardiorespiratory fitness. Participants with baseline total AHI between 5 and 14.9 events/h were classified as mild OSA and participants with baseline total AHI 15 ≥ events/h were classified as moderate-to-severe OSA.

RESULTS

Fifteen participants completed 18 exercise sessions. Significant differences between OSA categories at baseline were observed for sleep characteristics, but not for fitness or executive function. Wilcoxon Signed Rank Tests showed significant increases in median values for the Flanker Test in the moderate-to-severe category only, z = 2.429, p < .015, η² = .737.

CONCLUSION

Six weeks of exercise improved executive function in overweight individuals with moderate-to-severe OSA, but not in those with mild OSA.

The Association Between Sleep and Musculoskeletal Injuries in Military Personnel: A Systematic Review

INTRODUCTION

Musculoskeletal injuries (MSKIs) are a significant health problem in the military. Accordingly, identifying risk factors associated with MSKI to develop targeted strategies that attenuate injury risk remains a top priority within the military. Insufficient sleep has garnered increased attention as a potential risk factor for MSKI in both civilians and military personnel. Yet, there are no systematic evaluations of the potential association between sleep and MSKI in the military. The purpose of this review is to examine the relationship between sleep and injury in military personnel.

MATERIALS AND METHODS

Literature searches were performed in multiple electronic databases using keywords relevant to sleep quantity and quality, MSKI, and military populations. Two investigators independently assessed the methodological quality of each study using the Newcastle-Ottawa Scale for cohort studies or an adapted form of this scale for cross-sectional studies.

RESULTS

The search yielded 2402 total citations, with 8 studies (3 cohort and 5 cross-sectional) fitting the inclusion criteria. Overall, the systematic review found 5 of the 8 reviewed studies supporting an association between sleep (quality and duration) and MSKI in military personnel. Specifically, poor sleep was associated with increased injury incidence in 2 cohort and 3 cross-sectional studies.

CONCLUSION

This is the first systematic review to evaluate the published literature on the association between sleep and MSKI risk in military populations. Although there is currently limited research on this topic, findings suggest that sleep is associated with MSKI and should be considered when designing strategies aimed at reducing MSKI risk in military personnel.

The effects of exercise training on vascular function among overweight adults with obstructive sleep apnea

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity due, in part, to impaired vascular function. Exercise confers cardioprotection by improving vascular health. Yet, whether OSA severity affects the vascular improvements conferred with exercise training is not known. Overweight (body mass index (BMI) >27 kg/m²) adults were evaluated for OSA and enrolled in a six-week exercise intervention. Baseline assessments of brachial artery flow-mediated dilation (BAFMD), central augmentation index (AIx) and pulse wave velocity (PWV) were repeated post training. Fifty-one participants (25 men; 26 women) completed the study. Despite improved aerobic capacity (p=0.0005) and total fat mass (p=0.0005), no change in vascular function was observed. Participants were divided into two severity groups according to their baseline total apnea-hypopnea index (AHI) as either 5 to 14.9 events•hr^-1 (n= 21; Age=48 ± 7 yrs; BMI=33.7 ± 4.6kg•m^-2) or 15 ≥events•hr^-1 (n=30; Age=56 ± 13 yrs; BMI = 34.3 ± 4.2 kg•m^-2). No effect of OSA group was observed for BAFMD (p=0.82), AIx (p=0.37) or PWV (p=0.44), suggesting that OSA severity does not influence the effect of exercise on vascular function. The vascular effects of extended exercise programs of greater intensity in overweight OSA patients should be examined.

How can exercise reduce cardiovascular disease risk? A primer for the clinician

Despite advances in drug development and medical treatments, cardiovascular diseases (CVDs) remain a leading cause of mortality across the globe. Fortunately, CVD can be delayed by engaging in appropriate lifestyle behaviors. An abundance of epidemiological evidence supports a direct association between increased levels of physical activity or cardiovascular fitness and reduced premature CVD morbidity and mortality. These data have been used as the basis for many medical organizations to issue physical activity guidelines to citizens to improve physical activity participation and, ultimately, reduce the risk of CVDs and other chronic diseases. Despite these efforts, physical activity participation around the globe remains low. The medical professional is well suited to promote exercise as a preventative treatment for CVD, although promotion efforts may be less effective without a clear understanding of the mechanisms through which exercise confers cardioprotection. Thus, the purpose of this review is to highlight the cardioprotective effects of exercise training and to explore the underlying mechanistic pathways that might explain these benefits. The review will focus on those physiological pathways that are directly involved in atherosclerotic disease development. They include hypercholesterolemia, hypertension, chronic inflammation, and insulin resistance.

Body Composition Values of NCAA Division 1 Female Athletes Derived From Dual-Energy X-Ray Absorptiometry

ABSTRACT

Dobrosielski, DA, Leppert, KM, Knuth, ND, Wilder, JN, Kovacs, L, and Lisman, PJ. Body composition values of NCAA Division 1 female athletes derived from dual-energy x-ray absorptiometry. J Strength Cond Res 35(10): 2886-2893, 2021-This study generated descriptive data for regional and total body composition and bone mineral density (BMD) measures using dual-energy x-ray absorptiometry (DXA) across 12 NCAA Division 1 female competitive sports. Two hundred seventy-eight female collegiate athletes underwent DXA: basketball (BB; n = 28), cross country (CC = 11), field hockey (FH; n = 35), gymnastics (GYM; n = 23), lacrosse (LAX; n = 48), soccer (SOC; CC = 27), softball (SB; n = 24), swimming and diving (SW; n = 35), tennis (TN; n = 11), track and field ([TR-throw; n = 10]; [TR-run; n = 10]), and volleyball (VB; n = 16). Descriptive statistics for all body composition and BMD measures were calculated. Group mean differences in all regional and total body composition (all, p < 0.001; η2 range = 0.177-0.365) and BMD (all, p < 0.001; η2 range = 0.317-0.383) measures were observed between teams. The total BF% for gymnasts (23.5%) was lower than TN, FH, LAX, SB, and TR-throw (mean difference range: -4.6 to -12.9%, all p < 0.01); TR-throw had the highest total BF% (36.4%). Cross country had lower total BMD (1.17 g·cm-2) than FH, TR-throw, LAX, GYM, SOC, SB, VB, and BB (mean difference range: -0.12 to -0.26 g·cm-2, all p < 0.01); BB and TR-throw had the highest total BMD (1.40 and 1.43 g·cm-2, respectively). Our data confirm that regional and total body composition and BMD measures varied across female collegiate sports. These findings may assist sports medicine and strength and conditioning practitioners with identifying sport-specific goal values for BF% and BMD to optimize program design.

The Association Between Poor Sleep and the Incidence of Sport and Physical Training-Related Injuries in Adult Athletic Populations: A Systematic Review

BACKGROUND

The importance of achieving an adequate amount of sleep to optimize health and athletic performance is well recognized. Yet, a systematic evidence compilation of the risk for sport-related injury in adult athletic populations due to poor sleep does not exist.

OBJECTIVE

To examine the association between poor sleep and sport and physical training-related injuries in adult athletic populations.

DATA SOURCES

Electronic databases were searched using keywords relevant to sleep quantity and quality, and musculoskeletal injury and sport-related concussion (SRC).

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies were included in this systematic review if they were comprised of adult athletic populations, reported measures of sleep quantity or quality, followed participants prospectively for injury, and reported an association between sleep and incidence of sport or physical training-related injury.

STUDY APPRAISAL

The methodological quality of each study was assessed using the Newcastle-Ottawa Scale for Cohort Studies.

RESULTS

From our review of 12 prospective cohort studies, we found limited evidence supporting an association between poor sleep and injury in adult athletic populations. Specifically, there is (a) insufficient evidence supporting the associations between poor sleep and increased risk of injury in specific groups of athletic adults, including professional or elite athletes, collegiate athletes, elite or collegiate dancers, and endurance sport athletes; and (b) limited evidence of an association between poor sleep and increased risk of SRC in collegiate athletes.

CONCLUSIONS

The current evidence does not support poor sleep as an independent risk factor for increased risk of sport or physical training-related injuries in adult athletic populations. Given the methodological heterogeneity and limitations across previous studies, more prospective studies are required to determine the association between sleep and injury in this population.

Positional Analysis of Body Composition Using Dual-Energy X-Ray Absorptiometry in National Collegiate Athletic Association Division I Football and Men's Lacrosse

Zabriskie, HA, Dobrosielski, DA, Leppert, KM, Droege, AJ, Knuth, ND, and Lisman, PJ. Positional analysis of body composition using dual-energy X-ray absorptiometry in National Collegiate Athletic Association Division I football and men's lacrosse. J Strength Cond Res XX(X): 000-000, 2020-Despite the widespread use of dual-energy X-ray absorptiometry (DXA), few studies have examined differences in body composition between positions within sports and none have reported DXA-derived body composition reference values for men's lacrosse. The purpose of this study was to examine differences in measures of total and regional body composition and bone mineral density (BMD) using DXA across sport positions in a large cohort of National Collegiate Athletic Association Division I male lacrosse and football players. A total of 294 male athletes (football, n = 196; lacrosse, n = 98) underwent DXA. One-way analysis of variance or Kruskal-Wallis tests were used to examine whether body composition variables differed by sports position. In football, position was a significant determinant for every compositional variable in football athletes (all, p < 0.05; effect size range = 0.24-0.79). Offensive linemen had the highest total body fat percentage (30.1 ± 2.9%), followed by fullbacks (26.7 ± 3.3%) and defensive linemen (24.6 ± 5.7%); wide receivers had the lowest (14.5 ± 2.1%). For total body BMD, defensive linemen had the highest (1.70 ± 0.09 g·cm), followed by linebackers (1.67 ± 0.09 g·cm) and offensive linemen (1.65 ± 0.09 g·cm); kickers had the lowest (1.45 ± 0.11 g·cm) BMD. In lacrosse, no differences were found between positions for any total or regional body composition and BMD measure (all, p > 0.05). Our data confirm that total and regional measures of body composition and BMD vary across positions in football but not in men's lacrosse. Unlike football, similarities in body composition among lacrosse players may indicate that the uniformity of training demands or preferred player attributes in team selection outweigh the unique positional demands in gameplay.

Diet and exercise in the management of obstructive sleep apnoea and cardiovascular disease risk

Obstructive sleep apnoea (OSA) is associated with increased cardiovascular disease (CVD) morbidity and mortality. It is accepted that OSA and obesity commonly coexist. The American Academy of Sleep Medicine recommends dietary-induced weight loss and exercise as lifestyle treatment options for OSA. However, most clinical trials upon which this recommendation is based have focused on establishing the effectiveness of calorie-restricted, often low-fat diets for improving OSA severity, whereas less attention has been given to the means through which weight loss is achieved (e.g. altered dietary quality) or whether diet or exercise mediates the associations between reduced weight, improved OSA severity and the CVD substrate. The current evidence suggests that the benefits of a low-carbohydrate or Mediterranean diet in overweight and obese individuals go beyond the recognised benefits of weight reduction. In addition, exercise has an independent protective effect on vascular health, which may counter the increased oxidative stress, inflammation and sympathetic activation that occur in OSA patients. This review aims to expand our understanding of the effects of diet and exercise on OSA and associated CVD complications, and sets the stage for continued research designed to explore optimal lifestyle strategies for reducing the CVD burden in OSA patients.

The Association between Regional Fat Distribution and Acute Mountain Sickness in Young Hikers

Acute mountain sickness (AMS) can occur upon rapid ascent from low to high altitude. This study examined the association between central adiposity and the development of AMS in young adults during a high-altitude hike. Total and regional body fat were measured at sea level using dual-energy X-ray absorptiometry. Within 24 h of arriving in Cusco, Peru (3 400 meters) participants embarked on a 14-mile hike across the Andes Mountain range in southern Peru. Symptoms of AMS were assessed using the Lake Louise score at 24 h (3 400 meters), 29 h (4 100 meters), 34 h (3 800 meters) and 53 h (2 900 meters). 14 participants (mean age 21±2 years; women: 11, men: 3) completed the study. The number of participants exhibiting at least mild AMS increased from 6 (54%) at 3 400 meters to 9 (64%) at 3 800 meters. A higher AMS score at 4 100 meters was associated with greater android (r=0.72, p<0.01), trunk (r=0.73, p<0.01) and total body (r=0.71, p<0.01) fat, but not with total body fat % (r=0.39, p=0.16). Our findings suggest that central obesity, but not total body fat per se, may be an important factor in the development of AMS.

Effects of exercise and weight loss in older adults with obstructive sleep apnea

PURPOSE

Obstructive sleep apnea (OSA) is prevalent among older individuals and is linked to increased cardiovascular disease morbidity. This study examined the change in OSA severity after exercise training and dietary-induced weight loss in older adults and the association of the changes in OSA severity, body composition, and aerobic capacity with arterial distensibility.

METHODS

Obese adults (n = 25) with OSA, age 60 yr or older, were instructed to participate in supervised exercise (3 d·wk) and follow a calorie-restricted diet. Baseline assessments of OSA parameters, body weight and composition, aerobic capacity, and arterial distensibility were repeated at 12 wk.

RESULTS

Nineteen participants completed the intervention. At 12 wk, there were reductions in body weight (-9%) and percentage of total body fat (-5%) and trunk fat (-8%) whereas aerobic capacity improved by 20% (all P < 0.01). The apnea-hypopnea index decreased by 10 events per hour (P < 0.01) and nocturnal SaO2 (mean SaO2) improved from 94.9% at baseline to 95.2% after intervention (P = 0.01). Arterial distensibility for the group was not different from that at baseline (P = 0.99), yet individual changes in distensibility were associated with the change in nocturnal desaturations (r = -0.49, P = 0.03) but not with the change in body weight, apnea-hypopnea index, or aerobic capacity.

CONCLUSIONS

The severity of OSA was reduced after an exercise and weight loss program among older adults, suggesting that this lifestyle approach may be an effective first-line nonsurgical and nonpharmacological treatment for older patients with OSA.

Lifestyle Intervention for Sleep Disturbances Among Overweight or Obese Individuals

Little is known about the effect of different lifestyle interventions on sleep disturbances among sedentary obese or overweight persons. We randomized men and women aged 35-65 to 6 months of a weight loss diet (D); or D combined with supervised exercise training D + E. Measurements were self-reported sleep disturbances, the Profile of Mood States questionnaire, BMI, total abdominal subcutaneous and visceral fat by magnetic resonance imaging, and aerobic fitness expressed as VO2peak. The groups did not differ in changes for body weight, abdominal total fat, VO2peak, and sleep disturbances. The novel finding herein is that reduced abdominal subcutaneous fat and depressive symptoms, with either D or D + E were associated with less sleep disturbances.

Associations between vasodilatory capacity, physical activity and sleep among younger and older adults

INTRODUCTION

Exercise promotes cardiovascular health through its direct impact on the vascular endothelium. Conversely, poor sleep quality is associated with endothelial dysfunction, which may explain the increased cardiovascular disease amongst poor sleepers. Yet, the influence of physical activity and poor sleep quality on vascular health is not clear.

PURPOSE

This study examined the relationships between forearm vasodilatory capacity, self-reported sleep quality and free-living, actigraphy-derived energy expenditure in a group of young and older community dwelling adults.

METHODS

Venous occlusion plethysmography determined baseline and peak forearm blood flow following reactive hyperemia. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). Measures of body composition were assessed using dual energy X-ray absorptiometry.

RESULTS

A total of 104 (61 young; 43 old) participants completed the study. In general, younger participants were more active, as determined by steps per day and average daily energy expenditure, but reported poorer sleep quality. In the combined sample, those who reported moderate sleep disturbances (PSQI total score; 11-15) had significantly lower vasodilatory capacity (16.8 ± 7.6 ml/100 ml/min) compared to those who reported no sleep disturbance (PSQI total score; 0-5) (22.3 ± 7.2 ml/100 ml/min) or mild sleep disturbance (PSQI total score; 6-10) (22.3 ± 8.1 ml/100 ml/min) (p < 0.01). After adjustment for physical activity, total body fat and age, moderately poor sleep remained an independent predictor of forearm vasodilatory capacity.

CONCLUSIONS

These findings suggest that any positive vascular benefits accrued through increased physical activity might be offset by the negative consequences of chronically disturbed sleep.

Lean Mass and Fat Mass as Contributors to Physical Fitness in an Overweight and Obese African American Population

OBJECTIVE

To determine the association of lean vs fat mass with fitness in healthy, overweight and obese African Americans from families with early-onset coronary disease.

DESIGN

Cross-sectional study.

SETTING

Baltimore, Maryland.

PARTICIPANTS

191 healthy, overweight, sedentary African Americans (69% women; aged 44.8 ± 11 years; body mass index 34 ± 5 kg/m2).

MAIN OUTCOME MEASURES

Anthropometrics, smoking, blood pressure, lipids, c-reactive protein, and glucose were assessed with standard methods; body composition was determined by dual energy X-ray absorptiometry; cardiorespiratory fitness was expressed as VO(2peak) attained during a maximal treadmill test.

RESULTS

In both men and women, greater lean mass was independently associated with higher VO(2peak) (P < .05) and explained > 21% of the variance in VO(2peak), adjusted for body mass index, fat mass, important covariables, and nonindependence of families.

CONCLUSIONS

In this cross-sectional study, lean mass was the key determinant of cardiorespiratory fitness, independent of sex, age, and magnitude of obesity. These data provide a strong rationale for examining whether interventions that increase lean mass may also improve fitness, even among high-risk overweight and obese African Americans.

Effect of exercise on abdominal fat loss in men and women with and without type 2 diabetes

OBJECTIVE

To examine the effect of exercise on abdominal adipose tissue in adults with and without type 2 diabetes mellitus (T2DM).

DESIGN

Post hoc analysis of two randomised controlled trials.

SETTING

Outpatient secondary prevention programme in Baltimore, Maryland, USA.

PARTICIPANTS

97 men and women with prehypertension, stage 1 or medically controlled hypertension. 49% of the sample was also diagnosed with T2DM.

INTERVENTION

All participants completed a 26-week (6.5 months) supervised aerobic and resistance exercise programme following American College of Sports Medicine guidelines.

PRIMARY AND SECONDARY OUTCOME MEASURES

The main outcomes in this post hoc analysis were total abdominal adipose tissue (TAT), subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) measured by MRI. Secondary outcomes were to determine whether the magnitude of abdominal fat change differed by diabetes status in men and women and to identify the predictors of change in abdominal fat distribution with exercise.

RESULTS

Overall, participants (mean age 61±6 years; 45% women) significantly improved peak oxygen uptake by 15% (p<0.01) and reduced weight by 2% (p<0.01). No change in SAT was observed after training. The reduction in VAT following exercise was attenuated in participants with T2DM (-3%) compared with participants who were non-T2DM (-18%, p<0.001 for the difference in change). The magnitude of VAT loss was associated with a decrease in body weight (r=0.50, p<0.001). After adjustment for weight change using regression analysis, diabetes status remained an independent predictor of the change in VAT.

CONCLUSIONS

Although participants with and without T2DM attained an exercise training effect as evidenced by increased fitness, VAT was unchanged in T2DM compared to those without T2DM, suggesting that these individuals may be resistant to this important benefit of exercise. The strategies for reducing cardiovascular disease risk in T2DM may be most effective when they include a weight loss component.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov Registry NCT00212303.

Glycemic associations with endothelial function and biomarkers among 5 ethnic groups: the Multi-Ethnic Study of Atherosclerosis and the Mediators of Atherosclerosis in South Asians Living in America studies

Background

The association of prediabetic states with endothelial dysfunction measured by flow‐mediated dilation (FMD) or endothelial biomarker levels remains controversial. We examined data from 5 ethnic groups to determine the association between glucose categories and FMD or endothelial biomarkers. We determined whether these associations vary by ethnic group or body mass index.

Methods and Results

We used data from 3516 participants from 5 race/ethnic groups with brachial FMD, endothelial biomarkers, and glucose category (normal, impaired fasting glucose [IFG], and diabetes) measures. There were significant ethnic differences in FMD, biomarker levels, and the prevalence of IFG and diabetes. However, all 5 ethnic groups showed similar patterns of higher FMD for the IFG group compared with the normal glucose and diabetes groups, which was most significant among whites and Asian Indians. Associations between glucose categories and endothelial biomarkers were more uniform, with the IFG and diabetes groups having higher biomarker levels than the normal glucose group. These associations did not change with further adjustment for fasting insulin levels. Whites with normal BMI had higher FMD values with higher glucose levels, but those with BMI in the overweight or obese categories had the inverse association (P for interaction=0.01).

Conclusions

The discordance of IFG being associated with higher FMD but more abnormal endothelial biomarker levels is a novel finding. This higher FMD for the IFG group was most notable in whites of normal BMI. The higher FMD among those with impaired fasting glucose may reflect differences in insulin signaling pathways between the endothelium and skeletal muscle.

Effect of exercise on blood pressure in type 2 diabetes: a randomized controlled trial

BACKGROUND

Increased blood pressure (BP) in type 2 diabetes (T2DM) markedly increases cardiovascular disease morbidity and mortality risk compared to having increased BP alone.

OBJECTIVE

To investigate whether exercise reduces suboptimal levels of untreated suboptimal BP or treated hypertension.

DESIGN

Prospective, randomized controlled trial for 6 months.

SETTING

Single center in Baltimore, MD, USA.

PATIENTS

140 participants with T2DM not requiring insulin and untreated SBP of 120-159 or DBP of 85-99 mmHg, or, if being treated for hypertension, any SBP <159 mmHg or DBP<99 mmHg; 114 completed the study.

INTERVENTION

Supervised exercise, 3 times per week for 6 months compared with general advice about physical activity.

MEASUREMENTS

Resting SBP and DBP (primary outcome); diabetes status, arterial stiffness assessed as carotid-femoral pulse-wave velocity (PWV), body composition and fitness (secondary outcomes).

RESULTS

Overall baseline BP was 126.8 ± 13.5 / 71.7 ± 9.0 mmHg, with no group differences. At 6 months, BP was unchanged from baseline in either group, BP 125.8 ± 13.2 / 70.7 ± 8.8 mmHg in controls; and 126.0 ± 14.2 / 70.3 ± 9.0 mmHg in exercisers, despite attaining a training effects as evidenced by increased aerobic and strength fitness and lean mass and reduced fat mass (all p<0.05), Overall baseline PWV was 959.9 ± 333.1 cm/s, with no group difference. At 6-months, PWV did not change and was not different between group; exercisers, 923.7 ± 319.8 cm/s, 905.5 ± 344.7, controls.

LIMITATIONS

A completion rate of 81 %.

CONCLUSIONS

Though exercisers improve fitness and body composition, there were no reductions in BP. The lack of change in arterial stiffness suggests a resistance to exercise-induced BP reduction in persons with T2DM.

Predictors of exercise intervention dropout in sedentary individuals with type 2 diabetes

PURPOSE

While the benefits of exercise in people with type 2 diabetes mellitus is well-known, knowledge of factors associated with dropouts of exercise intervention trials is limited. Examining clinical and psychosocial factors related to dropout is a necessary first step to developing an effective exercise program. We examined the predictors of a randomized trial of exercise intervention dropout among sedentary individuals with type 2 diabetes mellitus.

METHODS

Participants (n = 140) were randomly allocated to a 6-month, 3 times per week exercise intervention, or to a control group. Psychological well-being was assessed using a 36-item Short Form Health Survey, the Profile of Mood States questionnaire, and an Exercise Self-Efficacy scale. Total percent body fat and abdominal subcutaneous and visceral fat were measured. Insulin resistance was assessed with the quantitative insulin sensitivity check index. Fitness was expressed as VO2 peak during treadmill testing.

RESULTS

There were significantly more dropouts in the exercise group than in the control group (r = 20.220; P < .01). Those who dropped out of the study had less exercise self-efficacy for lifting weight (r = 0.187; P < .05). Physiological parameters associated with dropouts included low fitness (r = 0.255; P < .01), higher insulin resistance (r = 0.167; P < .05), higher total percent body fat (r = 20.213; P < .05), and higher subcutaneous abdominal fat (r = 20.220; P < .05). In the multiple logistic regression model, exercise group assignment, insulin resistance, and fitness remained significant predictors of dropouts.

CONCLUSIONS

Special attention to the sedentary individuals with high insulin resistance and poor fitness should be incorporated into implementing exercise programs to improve diabetes treatment.

A randomized trial of exercise for blood pressure reduction in type 2 diabetes: effect on flow-mediated dilation and circulating biomarkers of endothelial function

OBJECTIVE

To investigate the effect of an exercise intervention on flow-mediated dilation (FMD) and circulating endothelial biomarkers in adults with type 2 diabetes (T2DM).

METHODS

Sedentary adults (n = 140), aged 40-65, with T2DM and untreated pre or Stage I hypertension or treated hypertension were randomized to a 6-month, supervised, exercise program (3× week) or a sedentary control. Assessments included BMI, body and visceral fat, blood pressure, lipids, HbA1c, insulin sensitivity (QUICKI), fitness, FMD, E-selectin, P-selectin, intracellular and vascular cellular adhesion molecules (ICAM, VCAM), and tissue plasminogen activator (tPA). Intervention effects were compared by t-tests. Pearson's correlations were calculated between changes in cardiovascular risk factors and endothelial outcomes.

RESULTS

Exercisers significantly improved BMI (-0.6 kg/m(2)), body fat % (-1.4%), HbA1c (-0.5%), and fitness (2.9 mL/kg min) vs. controls (p < 0.05). However, there were no differences between groups in changes in FMD, E-selectin, P-selectin, ICAM, VCAM, or tPA. Among exercisers, changes in cardiovascular risk factors correlated with several biomarkers. Decreased P-selectin correlated with decreased BMI (r = 0.29, p = 0.04) and increased HDL cholesterol (r = -0.36, p = 0.01). Decreased ICAM correlated with decreased triglycerides and HbA1c (r = 0.30, p = 0.04; r = 0.31, p = 0.03) and increased QUICKI (r = - 0.28, p = 0.05). Decreased tPA correlated with decreased total body and visceral fat (r = 0.28, p = 0.05; r = 0.38, p = 0.008) and increased QUICKI (r = -0.38, p = 0.007).

CONCLUSIONS

While exercise resulted in improved fitness, body composition, and glycemic control, there were no changes in FMD or circulating endothelial biomarkers. The associations of changes in cardiovascular risk factors and endothelial biomarkers suggest that improvement in risk factors could mediate the exercise-induced improvements in endothelial function seen in prior studies.

The association of arterial shear and flow-mediated dilation in diabetes

While adjusting flow-mediated dilation (FMD), a measure of vascular function, for shear rate may be important when evaluating endothelial-dependent vasodilation, the relationship of FMD with shear rate in study populations with cardiovascular risk factors is unclear. We aimed to investigate the association of four measures of shear rate (peak shear rate (SR(peak)) and shear rate area under the curve through 30 seconds (SR(AUC 0-30)), 60 seconds (SR(AUC 0-60)), and time to peak dilation (SR(AUC 0-ttp))) with FMD in 50 study subjects with type 2 diabetes and mild hypertension undergoing baseline FMD testing for an exercise intervention trial. Associations among measures of shear rate and FMD were evaluated using Pearson's correlations and R(2). The four measures of shear rate were highly correlated within subjects, with Pearson's correlations ranging from 0.783 (p < 0.001) to 0.972 (p < 0.001). FMD was associated with each measure of shear rate, having a correlation of 0.576 (p < 0.001) with SR(AUC 0-30), 0.529 (p < 0.001) with SR(AUC 0-60), and 0.512 (p < 0.001) with SR(peak). Nine of 50 subjects (18%) did not dilate following the shear stimulus. Among the 41 responders, FMD had a correlation of 0.517 (p < 0.001) with SR(AUC 0-ttp) and similar correlations to those found in the full sample for SR(AUC 0-30), SR(AUC 0-60), and SR(peak). In conclusion, shear rate appears to explain up to a third of between-person variability in FMD response and our results support the reporting of shear rate and FMD with and without adjustment for shear rate in similar clinical populations with CVD risk factors.

Lean mass predicts hip geometry in men and women with non-insulin-requiring type 2 diabetes mellitus

Persons with type 2 diabetes mellitus (T2DM) are at increased risk for hip fracture despite normal bone mineral density (BMD). The contribution of body composition to hip geometry, a measure of hip strength, has not been studied in T2DM. We hypothesized that lean mass would predict hip geometry. Subjects (n=134) for this cross-sectional analysis were men and women aged 56 ± 6yr with non-insulin-requiring T2DM. Fat and lean mass were measured with dual-energy X-ray absorptiometry (DXA). Abdominal fat was measured with magnetic resonance imaging. Hip geometry parameters including section modulus, cross-sectional area, and buckling ratio were estimated from DXA using validated formulae. Subjects had normal BMD, elevated body mass indices (29-41 kg/m(2)), and controlled T2DM (hemoglobin A1c: 5.1-8.3%). In bivariate analysis, lean mass was positively associated with section modulus and cross-sectional area in both sexes (r=0.36-0.55, p<0.05). In multivariate analyses, lean mass remained a significant predictor of all hip strength estimates in both sexes. In women alone, fat mass predicted parameters of hip strength. These data demonstrate that lean mass is significantly associated with hip strength in subjects with non-insulin-requiring T2DM. Resistance exercises that build lean mass may be an intervention for hip fracture prevention in T2DM, although additional research is needed.

Lean mass and fat mass predict bone mineral density in middle-aged individuals with noninsulin-requiring type 2 diabetes mellitus

OBJECTIVE

Despite high bone mineral density (BMD), persons with type 2 diabetes are at greater risk of fracture. The relationship between body composition and BMD in noninsulin-requiring diabetes is unclear. The aim was to examine how fat and lean mass independently affect the skeleton in this population.

RESEARCH DESIGN AND METHODS

Subjects for this cross-sectional analysis were men (n = 78) and women (n = 56) aged 40-65 years (56 ± 6 years) with uncomplicated, noninsulin-requiring type 2 diabetes. Total body fat and lean mass, total body, hip and lumbar spine BMD were measured with dual energy X-ray absorptiometry. Magnetic resonance imaging measured total abdominal, visceral and subcutaneous (SQ) fat.

RESULTS

Subjects had normal all-site BMD and were obese to overweight (body mass index 29-41 kg/m(2)) with controlled diabetes (HbA1c women 6·6 ± 1·2%, men 6·7 ± 1·6%). Lean mass was positively associated with total body, hip, femoral neck and hip BMD in both sexes. Fat mass, abdominal total and SQ fat were associated with total body and hip BMD in women. In multivariate analyses adjusted for sex, lean mass significantly predicted total, hip and femoral neck BMD in men and women. In unadjusted models, lean mass continued to predict BMD at these sites in men; fat mass also predicted total body, femoral and hip BMD in women.

CONCLUSIONS

In men and women with uncomplicated, noninsulin-requiring diabetes, lean mass significantly predicted BMD at the total body, hip and femoral neck. Further research is needed to determine whether acquisition or maintenance of lean mass in T2DM can prevent hip fracture in this at-risk population.

Maximal heart rate prediction in adults that are overweight or obese

An accurate predictor of maximal heart rate (MHR) is necessary to prescribe safe and effective exercise in those considered overweight and obese when actual measurement of MHR is unavailable or contraindicated. To date, accuracy of MHR prediction equations in individuals that are overweight or obese has not been well established. The purpose of this study was to examine the accuracy of 3 equations for predicting MHR in adults that are overweight or obese. One hundred seventy-three sedentary adults that were overweight or obese enrolled in weight-loss study and performed a VO₂peak treadmill test before the start of the weight loss treatment. A total of 132 of the 173 participants met conditions for achieving maximal exercise testing criteria and were included in this study. Maximal heart rate values determined from VO₂peak treadmill tests were compared across gender, age, and weight status with the following prediction equations: (a) 220 - age, (b) 208 - 0.7 × age, and (c) 200 - 0.48 × age. Among 20- to 40-year-old participants, actual MHR averaged 180 ± 9 b·min⁻¹ and was overestimated (p < 0.001) at 186 ± 5 b·min⁻¹ with the 220 - age equation. Weight status did not affect predictive accuracy of any of the 3 equations. For all participants, the equation, 200-0.48 × age estimated MHR to be 178 ± 4 b·min⁻¹, which was greater than the actual value (175 ± 12, p = 0.005). Prediction equations showed close agreement to actual MHR, with 208 - 0.7 × age being the most accurate.

Modification of vascular function after handgrip exercise training in 73- to 90-yr-old men

PURPOSE

To examine the influence of a unilateral exercise training protocol on brachial artery reactivity (BAR) in 12 men (aged 81 +/- 5 yr).

METHODS

Brachial artery diameters and blood flow parameters were assessed, in both arms, using high-resolution ultrasonography, before and after 5 min of forearm occlusion, before and at the end of each week of a 4-wk training program. Training consisted of a unilateral handgrip training protocol (nondominant arm) at 60% of maximal voluntary handgrip strength, performed for 4 wk, 4 d x wk(-1), 20 min per session, and a cadence of one contraction per 4 s.

RESULTS

After training, handgrip strength increased 6.2% (baseline = 32.4 +/- 7.0 kg vs week 4 = 34.4 +/- 6.7 kg) in the trained arm only but failed to reach statistical significance (P = 0.10). No statistical changes were observed for blood pressure or resting HR. In contrast, BAR increased 45% (Pre = 2.9% vs Post = 4.1%, P = 0.05) in the trained arm only. Improvements in BAR were observed after the second week of training, without significant changes in the main vasodilatory trigger, defined as the relevant shear stimulus after forearm occlusion (P > 0.05).

CONCLUSIONS

These data indicate that a localized short-term exercise program results in significant improvements in vascular function in the trained arm of elderly men compared with the control arm. Furthermore, the findings indicate a statistically significant increase in BAR at the end of the second week of training, despite a similar trigger for dilation versus before training.

Plasma nitrite flux predicts exercise performance in peripheral arterial disease after 3months of exercise training

Plasma nitrite is a major oxidation product of nitric oxide. It has also recently been suggested to perform an endocrine-like function as a nitric oxide donor in hypoxic tissues, allowing vasodilation. Exercise performance is limited in peripheral arterial disease because of an inadequate blood supply to working tissues. We hypothesized that exercise training in peripheral arterial disease subjects will improve "plasma nitrite flux" and endothelial function, to accompany increased exercise performance. Peripheral arterial disease subjects were tested at baseline and after 3 months supervised or home exercise training. Venous blood (arm) was drawn at rest and 10 min after a maximal graded treadmill test. Samples were added to heparin and centrifuged and plasma was snap-frozen for analysis by reductive chemiluminescence. Brachial artery endothelial function was measured in response to a hyperemic stimulus (flow-mediated dilation). At 3 months the peripheral arterial disease-supervised exercise group showed increases in claudication onset pain time (+138 s, p< or =0.05), peak walking time (+260 s, p< or =0.01), VO(2peak) (1.3 ml/kg/min, p< or =0.05), brachial artery flow-mediated dilation (+2%, p< or =0.05), and plasma nitrite flux (+33% p< or =0.05). There were no changes in the peripheral arterial disease-home exercise group. The change in plasma nitrite flux predicted the change in claudication onset pain (r(2)=0.59, p< or =0.01). These findings suggest that changes in plasma nitrite are related to endothelial function and predict exercise performance in peripheral arterial disease.

The association between flow-mediated dilation and physical function in older men

The probability that an individual is able to live independently decreases sharply below the threshold score of 57 units on the physical functional performance (PFP-10) test.

PURPOSE

To examine the relation between brachial artery flow-mediated dilation (BAFMD) on individual and total scores on the PFP-10. We hypothesized that lower scores on the PFP-10 test would be associated with lower BAFMD.

METHODS

Sixty-four men (age, 84 +/- 11 yr) from the Louisiana Healthy Aging Study were studied. Participants were classified by their performance on the PFP-10 test (Class I, score <26; Class II, score between 26 and 57; and Class III, score > 57). BAFMD was assessed after 5 min of forearm occlusion, using high-resolution ultrasonography.

RESULTS

The average total score on the PFP-10 test and BAFMD were 42.9 +/- 22 U and 2.76 +/- 2.13%, respectively. The BAFMD was associated with total PFP-10 score (r = 0.45, P = 0.0001) and age (r = -0.36, P = 0.003). BAFMD was significantly different (P = 0.001) between the PFP-10 classes (Class I, 1.44% [95% CI, 0.49-2.39]; Class II, 2.67% [95% CI, 1.95-3.38]; and Class III, 4.01% [95% CI, 3.16-4.85]).

CONCLUSIONS

This study reports significant relationships between BAFMD and individual and combined measures of physical function in elderly men. More specifically, when individuals were categorized based on their PFP-10 total score, those in the highest functional class, exhibited the highest BAFMD, compared to those in the middle class, who had greater vasoreactivity than those in the lowest functional class.

Assessment of cardiovascular risk in collegiate football players and nonathletes

Collegiate American football players may be at risk for cardiovascular disease.

OBJECTIVE

to compare cardiovascular disease risk factors and cardiovascular structure and function parameters of football players, stratified by position, to a group of sedentary, nonathletes.

PARTICIPANTS

twenty-six collegiate football players and 13 nonathletes participated in this study.

METHODS

blood pressures, anthropometrics, and blood chemistries were obtained and analyzed using standardized procedures. Resting echocardiography was used to evaluate cardiac morphology and function. Brachial artery flow-mediated dilation was assessed using high-resolution ultrasonography.

RESULTS

the prevalence of the metabolic syndrome was significantly higher amongst the linemen compared to the skill-position players (46% versus 0%, p < .05). Mildly abnormal wall thickness was noted in 20% of the football players. No significant differences in vascular function were observed between the groups.

CONCLUSIONS

the increased prevalence of the metabolic syndrome and its components in the collegiate linemen may increase cardiovascular disease risk.

Plasma nitrite response in older women to a physical function test

BACKGROUND AND AIMS

Nitric oxide (NO) may play a critical role in facilitating the delivery of blood to active skeletal muscle, ultimately impacting functional health in older adults. Plasma nitrite is a useful marker of vascular NO bioavailability. The aim of the current investigation was to examine the effect of a widely used physical function test on plasma nitrite concentrations in older adults.

METHODS

Venous blood was drawn before, immediately following, and 10 minutes following the completion of a 400-m walk test. Blood samples were added to heparin and frozen for subsequent analysis of nitrite levels using chemiluminescence.

RESULTS

Twenty six (79±4 yrs) women participated in this study. Plasma nitrite levels decreased approximately 22% from baseline following a 400-m walk. Percent change in plasma nitrite was related to walking speed (r=-0.550, p=0.004).

CONCLUSIONS

These data suggest an alteration in plasma nitrite concentration following a functional test which may impact functional health.