Cardiovascular disease risk factors and blood pressure response during exercise in healthy children and adolescents: the European Youth Heart Study

Blood pressure response to exercise in children and adolescents

Blood pressure changes during exercise are part of the physiological response to physical activity. Exercise stress testing can detect an exaggerated blood pressure response in children and adolescent. It is applied for certain clinical conditions, but is also commonly used as part of the assessment of athletes. The interpretation of blood pressure values in response to exercise during childhood and adolescence requires appropriate reference data. We discuss the available reference values and their limitations with regard to device, exercise protocol and normalization. While the link between an exaggerated blood pressure response and cardiovascular events and mortality has been demonstrated for adults, the situation is less clear for children and adolescents. We discuss the existing evidence and propose that under certain circumstances it might be reasonable to have children and adolescents undergo exercise stress testing as a rather non-invasive procedure to add additional information with regard to their cardiovascular risk profile. Based on the existing data future studies are needed to extend our current knowledge on possible links between the presence of certain clinical conditions, the detectability of an exaggerated blood pressure response during childhood and adolescence and the risk of developing cardiovascular morbidity and mortality in later life.

The relationships between physical activity, lumbar multifidus muscle morphology, and low back pain from childhood to early adulthood: a 12-year longitudinal study

We investigated the longitudinal associations between physical activity (PA), lumbar multifidus morphology, and impactful low back pain (LBP) in young people. Nine-year-old children were recruited from 25 primary schools and followed up at age 13, 16, and 21 years. We measured PA with accelerometers at age 9, 13, and 16; quantified patterns of lumbar multifidus intramuscular adipose tissue (IMAT) change from 13 to 16 years using magnetic resonance imaging; and recorded LBP and its impact with standardised questionnaires and interviews. Associations were examined with crude and adjusted logistic or multinomial models and reported with odds ratios (OR) or relative risk ratios (RRR). We included data from 364 children (mean[SD] age = 9.7[.4] years). PA behaviour was not associated with LBP. Having persistently high IMAT levels at age 13 and 16 was associated with greater odds of LBP (OR[95% CI] = 2.98[1.17 to 7.58]). Increased time in moderate and vigorous intensity PA was associated with a lower risk of higher IMAT patterns (RRR[95% CI] = .67[.46 to .96] to .74[.55 to 1.00]). All associations became non-significant after adjusting for sex and body mass index (BMI). Future studies investigating the relationships between PA behaviour, lumbar multifidus IMAT, and impactful LBP should account for potential confounding by sex and BMI.

Assessment of diastolic blood pressure with the auscultatory method in children and adolescents under exercise conditions

Controversy surrounds whether to define resting diastolic blood pressure (DBP) as the onset of the fourth or fifth Korotkoff phase (K4, sound muffling, or K5, sound disappearance) in children and adolescents. Although undetectable in some children (due to sounds continuing to zero cuff pressure), K5 is currently recommended for consistency with adult practice and because K4 can be difficult to discern or undetectable. However, to our knowledge, no studies have specifically assessed the reliability of measuring DBP with K4 and K5 in children and adolescents under exercise conditions. We therefore measured DBP before and immediately after a Bruce protocol stress test in 90 children and adolescents aged 12.3 ± 3.5 years (mean ± SD) in a cardiology clinic setting. When detected, K4 and K5 were 63.5 ± 9.2 and 60.2 ± 12.6 mmHg, respectively, at rest and 59.2 ± 14.6 mmHg (p = 0.028 vs rest) and 52.9 ± 18.3 mmHg (p < 0.001), respectively, immediately post-exercise. K4 and K5 were not detected in 41% and 4% of participants at rest or in 29% and 37% post-exercise, respectively, while K5 resulted in unrealistic DBP values (<30 mmHg) in an additional 11%. Better exercise performance was associated with a more frequent absence of K5 post-exercise, and after excluding participants performing at <10th percentile for age, post-exercise K4 was absent in 23%, and plausible K5 values were not obtained in 59% (p < 0.001). Although neither K4 nor K5 alone were reliable measures of DBP immediately post-exercise, a novel hybrid approach using K4, if detected, or K5, if not, produced reasonable DBP measurements in 97% of participants.

Blood Pressure Response to Treadmill Cardiopulmonary Exercise Test in Children with Normal Cardiac Anatomy and Function

OBJECTIVES

To describe blood pressure (BP) responses during cardiopulmonary exercise testing (CPET) and propose criteria for abnormal BP responses in children with normal hearts.

STUDY DESIGN

Treadmill CPET data of children <18 years with normal hearts were retrospectively analyzed to evaluate BP responses to exercise at the Children's Hospital of Michigan over an 8-year period (2011-2018).

RESULTS

Our cohort included 1085 children (boys, 59%) aged 7-17 years. Analysis of variance for systolic BP at peak exercise (peak SBP) and SBP change (Δ) showed significant age and sex effects and age-sex interaction effects (P < .01). In the multiple linear regression model (P < .001, R square 0.298, standard error of the estimate 17.15), peak SBP (mm Hg) was predicted as 132.27 + 1.37 × age (years) + (3.31 × age (years) - 31.88) × sex [boys 1, girls 0]. The following criteria for abnormal BP responses in children were proposed: hypertensive BP response was defined by peak SBP with a 90% CI upper limit of reference values based on age and sex, and blunted BP response as ΔSBP <10 mm Hg for aged 7-11 years, <20 mm Hg for boys aged 12-17 years, and ΔSBP <10 mm Hg in girls.

CONCLUSIONS

BP responses to treadmill CPET depend on age and sex in children with normal hearts. The proposed criteria for abnormal BP responses in children during CPET will need to be verified in a large pediatric cohort.

Exercise Affects Blood Glucose Levels and Tissue Chromium Distribution in High-Fat Diet-Fed C57BL6 Mice

Obesity is commonly associated with hyperglycemia and type 2 diabetes and negatively affects chromium accumulation in tissues. Exercise prevents and controls obesity and type 2 diabetes. However, little information is available regarding chromium changes for regulating glucose homeostasis in high-fat diet (HFD)-fed animals/humans who exercise. Therefore, this study explored the effects of exercise and whether it alters chromium distribution in obese mice. Male C57BL6/J mice aged 4 weeks were randomly divided into two groups and fed either an HFD or standard diet (SD). Each group was subgrouped into two additional groups in which one subgroup was exposed to treadmill exercise for 12 weeks and the other comprised control mice. HFD-fed mice that exercised exhibited significant lower body weight gain, food/energy intake, daily food efficiency, and serum leptin and insulin levels than did HFD-fed control mice. Moreover, exercise reduced fasting glucose and enhanced insulin sensitivity and pancreatic β-cell function, as determined by homeostasis model assessment (HOMA)-insulin resistance and HOMA-β indices, respectively. Exercise also resulted in markedly higher chromium levels within the muscle, liver, fat tissues, and kidney but lower chromium levels in the bone and bloodstream in obese mice than in control mice. However, these changes were not noteworthy in SD-fed mice that exercised. Thus, exercise prevents and controls HFD-induced obesity and may modulate chromium distribution in insulin target tissues.

Submaximal exercise blood pressure and cardiovascular structure in adolescence

PURPOSE

Dynamic exercise results in increased systolic blood pressure (BP). Irrespective of resting BP, some individuals may experience exaggerated rise in systolic BP with exercise, which in adulthood is associated with risk of hypertension, and cardiovascular (CV) disease. It is unknown if exercise BP is associated with markers of CV structure during adolescence. We examined this question in a large adolescent cohort taking account of the possible confounding effect of body composition and BP status.

METHODS

4036 adolescents (mean age 17.8 ± 0.4 years, 45% male), part of a UK population-based birth cohort study completed a sub-maximal step-test with BP immediately post-exercise. Sub-samples underwent comprehensive echocardiography for assessment of cardiac structure; arterial structure including aortic pulse wave velocity (PWV) and carotid intima-media thickness; and assessment of body composition by dual-energy X-ray absorptiometry (DXA).

RESULTS

Each 5 mm Hg higher post-exercise systolic BP was associated with CV structure, including 0.38 g/m2.7 (95% CI: 0.29, 0.47) greater left-ventricular mass index (LVMI), and 0.04 m/s (95% CI: 0.03, 0.04) greater aortic PWV. Adjustment for age, total body fat, lean mass and BP status attenuated, but did not abolish associations with LVMI (0.14 g/m2.7 per 5 mm Hg of post-exercise systolic BP; 95% CI 0.21, 0.39) or aortic PWV (0.03 m/s per 5 mm Hg of post-exercise systolic BP; 95% CI: 0.02, 0.04).

CONCLUSION

Submaximal exercise systolic BP is associated with markers of CV structure in adolescents. Given the clinical relevance of exercise BP in adulthood, such associations may have implications for CV disease screening in young people and risk in later life.

Physical activity for children with chronic disease; a narrative review and practical applications

BACKGROUND

Physical activity (PA) is associated with a diverse range of health benefits. International guidelines suggest that children should be participating in a minimum of 60 min of moderate to vigorous intensity PA per day to achieve these benefits. However, current guidelines are intended for healthy children, and thus may not be applicable to children with a chronic disease. Specifically, the dose of PA and disease specific exercise considerations are not included in these guidelines, leaving such children with few, if any, evidence-based informed suggestions pertaining to PA. Thus, the purpose of this narrative review was to consider current literature in the area of exercise as medicine and provide practical applications for exercise in five prevalent pediatric chronic diseases: respiratory, congenital heart, metabolic, systemic inflammatory/autoimmune, and cancer.

METHODS

For each disease, we present the pathophysiology of exercise intolerance, summarize the pediatric exercise intervention research, and provide PA suggestions.

RESULTS

Overall, exercise intolerance is prevalent in pediatric chronic disease. PA is important and safe for most children with a chronic disease, however exercise prescription should involve the entire health care team to create an individualized program.

CONCLUSIONS

Future research, including a systematic review to create evidence-based guidelines, is needed to better understand the safety and efficacy of exercise among children with chronic disease.

2016 European Society of Hypertension guidelines for the management of high blood pressure in children and adolescents

Increasing prevalence of hypertension (HTN) in children and adolescents has become a significant public health issue driving a considerable amount of research. Aspects discussed in this document include advances in the definition of HTN in 16 year or older, clinical significance of isolated systolic HTN in youth, the importance of out of office and central blood pressure measurement, new risk factors for HTN, methods to assess vascular phenotypes, clustering of cardiovascular risk factors and treatment strategies among others. The recommendations of the present document synthesize a considerable amount of scientific data and clinical experience and represent the best clinical wisdom upon which physicians, nurses and families should base their decisions. In addition, as they call attention to the burden of HTN in children and adolescents, and its contribution to the current epidemic of cardiovascular disease, these guidelines should encourage public policy makers to develop a global effort to improve identification and treatment of high blood pressure among children and adolescents.

Reference Values for Exercise Systolic Blood Pressure in 12- to 17-Year-Old Adolescents

OBJECTIVE

In adults, blood pressure (BP) during exercise has prognostic advantages compared to resting BP, whereas its relevance for children has not been revealed as clearly. Because exercise BP among young subjects might be of clinical importance, we sought to determine reference values in adolescents.

METHODS

BP recordings at rest and during a cycle ergometer test (1.5W/kg) were assessed in 492 teenagers (12-17 years) in the Kiel EX.PRESS. Study (EXercise and PRESSure). The resting systolic BP (SBP) values at the 90th and 95th percentile of the German reference population were applied on our resting SBP distribution. The resulting resting SBP percentiles were then used to propose exercise SBP limits.

RESULTS

Of our group, 12.4% exhibited a resting SBP ≥ 90th reference percentile, with 7.9% ≥ 95th percentile. The corresponding age group- and sex-specific percentiles were assigned to the exercise SBP distribution resulting in reference values for high normal and elevated SBP (upper limit, girls/boys, mm Hg): 172/172 for 12-13 years, 174.7/177.3 for 14-15 years, 178.5/201.3 for 16-17 years). Using these limits, exercise SBP values were elevated in 8.1%, 5.5% were within the high normal range. Normal resting SBP but at least high normal exercise SBP was found in 7.7%. In contrast, 7.4% were high normal or hypertensive at rest but normotensive during exercise.

CONCLUSIONS

Exercise BP is expected to be of additional use for the evaluation of BP in younger age groups. As long as prognostic data for exercise BP in adolescents are not available, the limits proposed might be considered in clinical practice.

Blood pressure response to exercise in young athletes aged 10 to 18 years

The aim of the study was to determine arterial blood pressure response to exercise in young athletes. The study group comprised 711 young athletes (457 boys, 254 girls) aged 10 to 18 years (mean 13.41 ± 3.12 years) who had been training for an average of 7.62 ± 4.2 h per week for an average of 4.01 ± 2.5 years. Participants with elevated arterial blood pressure above the 90th percentile at rest were excluded from investigation. A symptom-limited, multistage exercise test to exhaustion was performed using a Monark cycle ergometer. Arterial blood pressure was measured with an aneroid manometer in the third minute of each stage of the test. Mean systolic arterial blood pressure during peak exercise was significantly higher in boys than in girls: 183.21 ± 27.97 mm Hg and 170.97 ± 21.4 mm Hg, respectively (p = 0.03). Multivariate linear regression analysis showed that age and workload had significant effects on arterial blood pressure during the test. Systolic arterial blood pressure during the exercise can be described with the following equations: boys, SBPex (mm Hg) = -1.92 × age (years) + 0.55 × workload (W) + 120.84; girls, SBPex (mm Hg) = -0.88 × age (years) + 0.48 × workload (W) + 111.22. The study results describe reference values of arterial blood pressure during the exercise test. The presented equations and figures can help to assess whether the arterial blood pressure at each stage of the exercise test exceeds the normal range or not.

Effects of parental smoking on exercise systolic blood pressure in adolescents

Background

In adults, exercise blood pressure seems to be more closely related to cardiovascular risk than resting blood pressure; however, few data are available on the effects of familial risk factors, including smoking habits, on exercise blood pressure in adolescents.

Methods and Results

Blood pressure at rest and during exercise, parental smoking, and other familial risk factors were investigated in 532 adolescents aged 12 to 17 years (14.6±1.5 years) in the Kiel EX.PRESS. (EXercise PRESSure) Study. Exercise blood pressure was determined at 1.5 W/kg body weight using a standardized submaximal cycle ergometer test. Mean resting blood pressure was 113.1±12.8/57.2±7.1 mm Hg, and exercise blood pressure was 149.9±19.8/54.2±8.6 mm Hg. Parental smoking increased exercise systolic blood pressure (+4.0 mm Hg, 3.1 to 4.9; P=0.03) but not resting blood pressure of the subjects (adjusted for age, sex, height, body mass index percentile, fitness). Parental overweight and familial hypertension were related to both higher resting and exercise systolic blood pressure values, whereas associations with an inactive lifestyle and a low educational level of the parents were found only with adolescents’ blood pressure during exercise. The cumulative effect of familial risk factors on exercise systolic blood pressure was more pronounced than on blood pressure at rest.

Conclusions

Parental smoking might be a novel risk factor for higher blood pressure, especially during exercise. In addition, systolic blood pressure during a submaximal exercise test was more closely associated with familial risk factors than was resting blood pressure, even in adolescents.

Polychlorinated biphenyl exposure and glucose metabolism in 9-year-old Danish children

CONTEXT

Human exposure to polychlorinated biphenyls (PCBs) has been associated to type 2 diabetes in adults.

OBJECTIVE

We aimed to determine whether concurrent plasma PCB concentration was associated with markers of glucose metabolism in healthy children.

SETTING AND DESIGN

Cross-sectional study of 771 healthy Danish third grade school children ages 8-10 years in the municipality of Odense were recruited in 1997 through a two-stage cluster sampling from 25 schools stratified according to location and socioeconomic character; 509 (9.7 ± 0.8 y, 53% girls) had adequate amounts available for PCB analyses.

OUTCOME MEASURES

Fasting serum glucose and insulin were measured and a homeostasis assessment model of insulin resistance (HOMA-IR) and β-cell function (HOMA-B) calculated. Plasma PCB congeners and other persistent compounds were measured and ΣPCB calculated.

RESULTS

PCBs were present in plasma at low concentrations, median, 0.19 μg/g lipid (interquartile range, 0.12-0.31). After adjustment for putative confounding factors, the second, third, fourth, and fifth quintiles of total PCB were significantly inversely associated with serum insulin (-14.6%, -21.7%, -18.9%, -23.1%, P trend < .01), compared with the first quintile, but not with serum glucose (P = .45). HOMA-IR and HOMA-B were affected in the same direction due to the declining insulin levels with increasing PCB exposure. Similar results were found for individual PCB congeners, for βHCB (hexachlorobenzen) and pp-DDE (dichlorodiphenyldichloroethylene).

CONCLUSIONS

A strong inverse association between serum insulin and PCB exposure was found while fasting glucose remained within the expected narrow range. Our findings suggest that PCB may not exert effect through decreased peripheral insulin sensitivity, as seen in obese and low-fit children, but rather through a toxicity to β-cells. It remains to be demonstrated whether lower HOMA-B is caused by destruction of β-cell-reducing peripheral insulin resistance and thereby increase fasting glucose as previously found.

Cardiovascular fitness and haemodynamic responses to maximal cycle ergometer exercise test in children 6-8 years of age

We investigated cardiovascular fitness and haemodynamic responses to maximal cycle ergometer exercise test in children. The participants were a population sample of 425 children (204 girls, 221 boys) aged 6-8 years. Heart rate (HR) and systolic blood pressure (SBP) were measured from the beginning of pre-exercise rest to the end of recovery period. We provided reference values for peak workload and changes in HR and SBP during and after maximal exercise test in girls and boys. Girls had a lower cardiovascular fitness, indicated by peak workload per body weight [mean (2 s) 2.7 (0.9) vs. 3.1 (1.0) W · kg(-1), P < 0.001] and lean mass [mean (2 s) 3.5 (0.9) vs. 3.8 (1.0) W · kg(-1), P < 0.001] than boys. Plateau or decline in SBP close to the end of the test was found in about third of children and was considered a normal SBP response. Girls had a slower HR decrease within 2 min after the test than boys [mean (2 s) 53 (18) vs. 59 (22) beats · min(-1), P < 0.001]. The results are useful for physicians and exercise physiologists to evaluate cardiovascular fitness and haemodynamic responses to exercise in children and to detect children with low exercise tolerance or abnormal haemodynamic responses to exercise.

Blood pressure and plasma renin activity responses to different strategies to inhibit the renin-angiotensin-aldosterone system during exercise

OBJECTIVE

The effect of two different strategies for renin-angiotensin-aldosterone system (RAAS) blockade; direct renin inhibition (DRI) versus angiotensin receptor blockade (ARB) on blood pressure (BP) and plasma renin activity (PRA) was compared during exercise.

METHODS

Hypertensive adults were randomised to aliskiren (300 mg once daily, n=33) or valsartan (320 mg once daily, n=35). BP and PRA were measured during treadmill exercise (Bruce protocol), at baseline, end of treatment (eight weeks), and after treatment withdrawal (48 hours after last dose).

RESULTS

After eight weeks treatment, Aliskiren inhibited PRA (>80%) at rest and during exercise, with inhibition remaining undiminished 48 hours after treatment withdrawal. In contrast, valsartan increased PRA at rest, and more-so during exercise (>400%). Angiotensin receptor blockade, as indicated by PRA increase, was reduced, 48 hours after valsartan treatment withdrawal, suggesting more sustained RAAS blockade with aliskiren. Despite divergent effects on PRA, similar exercise-induced changes in BP were seen. The primary outcome, the rise in systolic BP from rest to peak exercise (baseline to after treatment withdrawal) did not differ between treatments (p=0.25).

CONCLUSION

Measurement of PRA is a more sensitive index of RAAS blockade than the BP response during exercise. Furthermore, after treatment withdrawal, aliskiren provides more sustained RAAS inhibition than valsartan at rest and during exercise.

Blood pressure responses during exercise testing-is up best for prognosis?

Exercise testing is not limited to observation of ischemic electrocardiographic findings during exercise, but also abnormal findings in blood pressure, heart rate, and exercise capacity are valuable. Individuals with exaggerated exercise blood pressure tend to develop future hypertension. Extensive elevation in systolic blood pressure during exercise has been found to increase the risk of left ventricular hypertrophy, myocardial infarction, cerebrovascular stroke, and cardiovascular death. Previous studies have revealed that blood pressure response to exercise is dependent on underlying heart disease and peripheral resistance. Therefore, subjects with documented cardiovascular disease may not be capable of generating a work-load to allow the manifestation of exercise-induced systolic hypertension. Systolic hypotension during exercise is associated with left ventricular dysfunction and inadequate cardiac output, and it is a marker of severe heart disease. Exercise testing with the definition of blood pressure can be performed in a logical way with test results used to decide on therapies and treatment strategies in addition to blood pressure at rest. A modest increment in blood pressure rise corresponding to work-load achieved during the exercise testing is the best sign from the prognostic point of view. The normal limits of exercise blood pressure response could be very helpful for clinicians.