Association of Physical Activity With Vascular Endothelial Function and Intima-Media Thickness

Impact of exercise and metabolic disorders on heat shock proteins and vascular inflammation

Heat shock proteins (Hsp) play critical roles in the body's self-defense under a variety of stresses, including heat shock, oxidative stress, radiation, and wounds, through the regulation of folding and functions of relevant cellular proteins. Exercise increases the levels of Hsp through elevated temperature, hormones, calcium fluxes, reactive oxygen species (ROS), or mechanical deformation of tissues. Isotonic contractions and endurance- type activities tend to increase Hsp60 and Hsp70. Eccentric muscle contractions lead to phosphorylation and translocation of Hsp25/27. Exercise-induced transient increases of Hsp inhibit the generation of inflammatory mediators and vascular inflammation. Metabolic disorders (hyperglycemia and dyslipidemia) are associated with type 1 diabetes (an autoimmune disease), type 2 diabetes (the common type of diabetes usually associated with obesity), and atherosclerotic cardiovascular disease. Metabolic disorders activate HSF/Hsp pathway, which was associated with oxidative stress, increased generation of inflammatory mediators, vascular inflammation, and cell injury. Knock down of heat shock factor-1 (HSF1) reduced the activation of key inflammatory mediators in vascular cells. Accumulating lines of evidence suggest that the activation of HSF/Hsp induced by exercise or metabolic disorders may play a dual role in inflammation. The benefits of exercise on inflammation and metabolism depend on the type, intensity, and duration of physical activity.

Puberty and microvascular function in healthy children and adolescents

OBJECTIVE

To determine the role of pubertal status on microvascular function in healthy children and adolescents.

STUDY DESIGN

Children and adolescents (n = 112; age 10-16 years) were investigated in 2 separate prospective cross-sectional studies. The main outcome measure was microvascular function, assessed by peripheral arterial tonometry to determine the reactive hyperemic index (RHI). Physical activity was assessed using 7-day recall in one study and accelerometry in the other study. Subjects were grouped based on their self-assessed pubertal status according to Tanner stage: group 1 (prepuberty, Tanner I), group 2 (mid-puberty, Tanner II/III), and group 3 (late puberty, Tanner IV/V). Stepwise multiple regression analysis was performed to identify independent predictors of the RHI.

RESULTS

Complete data were available for 94 subjects (55 females) with a median (IQR) age of 14 (3.0) years and a mean body mass index of 19.0 ± 3.63 kg·m(-2). Significant correlations with RHI were observed for Tanner stage (r = 0.569; P < .001), age (r = 0.567; P < .001), stature (r = 0.553; P < .001), systolic blood pressure (r = 0.494; P < .001), and body mass index (r = 0.309; P = .001), but not for sex and moderate-to-vigorous physical activity. In stepwise regression analysis, pubertal status was the only independent predictor of microvascular function (R(2) = 0.242; β = 0.492; P < .001). Prepubertal children (group 1) had a significantly lower RHI [1.14 (0.24)] compared with group 2 [1.65 (0.57)] and group 3 [1.70 (0.75)] (all P < .001).

CONCLUSION

Pubertal status was the main predictor of microvascular function in healthy children and adolescents. Future studies investigating microvascular function in this age group should assess and control for pubertal maturation.

Impact of acute exercise on brachial artery flow-mediated dilatation in young healthy people

Background

Although chronic effects of exercise on endothelial function are established, the impact of acute exercise on flow-mediated dilatation (FMD) of brachial artery has not been elucidated yet.

Methods

Eighty-six young healthy volunteers were prospectively enrolled from January 2011 to December 2011. The subjects completed FMD tests at rest and immediately after treadmill exercise test. Primary outcome was the impact of acute exercise on FMD, measured by the difference of FMD before and after exercise. Secondary outcomes were the relationship of gender and exercise habit with FMD.

Results

Seventy-four subjects who met the eligibility criteria were included for analysis. Thirty-five (47.3%) were male, and the mean age was 22.7±2.7 years. FMD was reduced after exercise (8.98±4.69 to 7.51±4.03%; P=0.017) and the reduction was found in female group (10.36±5.26 to 7.62±3.71%; P=0.002) but not in male group. Post-exercise FMD was significantly impaired in subjects who did not exercise regularly (6.92±3.13% versus 8.95±5.33%; P=0.003). The decrease of FMD after exercise was greater in female group (−2.75±5.28% versus 0.27±3.24%; P=0.003) and was associated with exercise habit (β=2.532; P=0.027).

Conclusions

In healthy young subjects, FMD was reduced after a bout of acute exercise. The impact of acute exercise showed significant differences according to gender and exercise habit. FMD impairment after acute exercise was observed in females and subjects without regular exercise.

Left ventricular mass and geometry in adolescence: early childhood determinants

It is not known whether birth weight and early childhood growth are associated with the development of cardiac left ventricular mass (LVM) in healthy adolescents. Left ventricular growth and geometric remodeling may have long-term consequences on cardiovascular health later in life. We studied the determinants of LVM and patterns of geometric remodeling in adolescents with specific emphasis on birth size and growth in early childhood. Left ventricular measurements were obtained with echocardiography in 418 adolescents at the age of 15 years in a prospective atherosclerosis prevention study, Special Turku Coronary Risk Factor Intervention Project (STRIP). Birth weight (P=0.0004), current pulse pressure (P=0.013), physical activity level (P=0.0024), weight (P<0.0001), and male sex (P<0.001) had an independent direct association with LVM in adolescents explaining 47% of the variation. Growth in early childhood was not associated with LVM in adolescents. Birth weight (P=0.0066), current weight (P<0.0001), and physical activity level (P=0.0017) were directly associated with left ventricular posterior wall thickness. Current weight was also directly associated with septal thickness (P<0.0001). Boys had a thicker septum than girls (P=0.0092). Normal relative wall thickness and increased left ventricular mass index (eccentric remodeling) (P<0.0001), as well as increase in both variables (concentric, increased LVM) (P=0.0003), were associated with higher body mass index. Our results indicate that birth weight has a long-lasting impact on LVM and normal body weight is beneficial for cardiac structure in adolescents.