Reduced arterial stiffness in very fit boys and girls

Arterial Stiffness and Carotid Intima-Media Thickness in Children Exposed to Smokeless Tobacco in Fetal Life

BACKGROUND

Arterial stiffening and increased intima-media thickness can be seen as early as childhood and are associated with increased risk of cardiovascular events in adult life. The authors hypothesized that exposure to prenatal smokeless tobacco (Swedish snus) without additional nicotine exposure after the breastfeeding period would be associated with increased arterial stiffness and intima-media thickening in preschool children.

METHODS AND RESULTS

This was a longitudinal follow-up cohort study of children aged 5 to 6 years exposed to high doses of nicotine in utero. Women exclusively using snus and unexposed controls were enrolled in early pregnancy (gestational age range, 6-12 weeks). Exposure data were collected during and after pregnancy with questionnaires from both groups. For this study, only children of women using >48 mg nicotine per day during their entire pregnancy were included in the exposure group. Outcomes were determined in 40 healthy children (21 exposed to snus in utero). Ultrasonography of the common carotid artery was used to determine carotid intima-media thickness and calculate arterial stiffness index from the relationship between pulsatile changes in arterial diameter and arterial pressure. Children exposed to snus in fetal life had higher carotid stiffness (median 4.1 [interquartile range (IQR), 2.4-5] versus 2.9 [IQR, 2.1-3.5]; P=0.014) than tobacco-free controls. Carotid strain (relative diameter change) was lower in children exposed to snus (mean 16% [SD, 5.7%] versus 21% [SD, 6.6%]) than in controls (P=0.015). Carotid intima-media thickness did not differ significantly between children exposed to snus and controls.

CONCLUSIONS

Exposure to snus during fetal life was associated with a stiffer carotid artery in preschool children.

Arterial Structure in 18-Year-Old Males Is Dependent on Physical Activity at 12 Years and Cumulative Cardiorespiratory Fitness From Puberty to Late Adolescence

PURPOSE

To evaluate the long-term effect of body composition, physical activity, and cardiorespiratory fitness (CRF) from puberty on arterial health in late adolescent males.

METHODS

The cumulative burden of physical activity (measured with accelerometer), CRF (VO2peak0.82), and body composition (body mass index, fat mass, and fat percentage) from puberty to late adolescence (sum of 4 time points from 12 to 18 y) was assessed in 102 males. Additional analysis on the first (T1) and last (T4) time points was performed. Intima-media thickness (IMT), carotid-femoral pulse wave velocity, and augmentation index adjusted to heart rate of 75 beats per minute (bpm) as dependent variables were measured at T4 and analyzed in multivariable regression models adjusted for known risk factors including maturation, blood pressure, and smoking habits.

RESULTS

T1 and cumulative body composition measures were independently associated with IMT, while cumulative (β = -0.011, P = .036) and T4 (β = -0.0.031, P = .001) CRF revealed independent associations with IMT. Individuals with moderate to vigorous physical activity >60 minutes per day at T1 showed relationship (β = -1.091, P = .026) with IMT independently of late adolescent physical activity. No significant relationship was present for arterial function.

CONCLUSION

Arterial structure in adolescent males is associated with physical activity at 12 years while relationship with CRF can be seen in late adolescence and cumulatively from puberty to late adolescence.

A Systematic Review of the Associations of Adiposity and Cardiorespiratory Fitness With Arterial Structure and Function in Nonclinical Children and Adolescents

PURPOSE

To summarize the evidence on associations of adiposity and cardiorespiratory fitness (CRF) with arterial structure and function in nonclinical children and adolescents.

METHODS

Two researchers conducted a search in 5 electronic databases in April 2022 to find studies in nonclinical youth (age 5-17.9 y) reporting multivariable associations. Studies were eligible if adiposity and/or CRF were used as the predictor and arterial structure and/or function was the outcome. The Quality Assessment Tool for Quantitative Studies was used to assess methodological quality for experimental studies, and a modified version was used for observational studies.

RESULTS

Ninety-nine studies (72.7% cross-sectional) were included. Ninety-four assessed associations between adiposity and arterial outcomes, most using overall body proportion (n = 71), abdominal (n = 52), or whole-body adiposity (n = 40). Most evidence was inconsistent or nonsignificant, but 59 studies suggested higher abdominal adiposity and worse body proportion were associated with adverse arterial outcomes. Twenty-one assessed associations between CRF and arterial outcomes, with findings inconsistent. Most evidence was rated weak in quality.

CONCLUSION

While high adiposity may contribute to poor arterial outcomes, evidence is limited regarding CRF. Future studies should disentangle these associations by studying youth with healthy adiposity but poor CRF, or vice versa, using longitudinal or experimental study designs.

Exercise and Carotid Properties in the Young-The KiGGS-2 Study

Background: Carotid intima-media thickness (cIMT) and stiffness (cS) are predictive markers of early vascular aging and atherosclerotic risk. This study assessed, whether exercise has protective effects on carotid structure and function or on vascular risk in the young. Methods: Volume and change of exercise (recreational and organized sports participation) of German adolescents and young adults was assessed within the prospective population-study KiGGS at KiGGS-Wave-1 (2009-2012) and KiGGS-Wave-2 (2014-2017) using standardized self-reporting questionnaires. CIMT and cS were measured by real-time B-mode ultrasound sequences with semi-automated edge-detection and automatic electrocardiogram-gated quality control in 2,893 participants (14-28 years, 49.6% female). A cumulative index for atherosclerotic risk (CV-R) included z-scores of mean arterial pressure, triglycerides, total/HDL-cholesterol-ratio, body mass index, and HbA1c. Results: At KiGGS-Wave-2 cross-sectional CV-R but not cS and cIMT was lower in all exercise-groups compared to "no exercise" (B = -0.73, 95%-CI = -1.26 to 0.19, p = 0.008). Longitudinal volume of exercise was negatively associated with CV-R (B = -0.37, 95%-CI = -0.74 to 0.00, p = 0.048) but not with cS and cIMT. Cross-sectional relative risk of elevated CV-R but not cS and cIMT was lower in all exercise-groups compared to "no exercise" (RR = 0.80, 95%-CI = 0.66 to 0.98, p = 0.033). High exercise volumes were associated with lower relative risk of elevated CV-R (RR = 0.80, 95%-CI = 0.65-0.97, p = 0.021) and cS in tendency but not with cIMT. Conclusions: Increased levels of exercise are associated with a better cardiovascular risk profile in young individuals, but not with cS and cIMT. Our study confirms previous recommendations on exercise in this age group without demonstrating a clear benefit on surrogate markers of vascular health.

Exercise Training Duration and Intensity Are Associated With Thicker Carotid Intima-Media Thickness but Improved Arterial Elasticity in Active Children and Adolescents

Even though exercise generally has a positive effect on health, intensive exercise can have adverse effects on the vascular system of adults. This study aimed to investigate the association between training duration and intensity and vascular structure and function in 427 physically active children and adolescents (14.0 ± 1.94 years). In this study, we examined carotid intima-media thickness (cIMT), carotid diameter, and cIMT:diameter-ratio as parameters of carotid arterial structure and arterial compliance (AC), stiffness index β (β), elastic modulus (Ep), and carotid pulse wave velocity (PWVβ) as parameters of carotid arterial function with high-resolution ultrasound. We collected central systolic blood pressure (cSBP) and aortic pulse wave velocity (aPWV) as parameters of central arterial stiffness with an oscillometric device. We used the MoMo Physical Activity Questionnaire to record training duration and intensity. Training duration (p = 0.022) and intensity (p = 0.024) were associated with higher cIMT. Further, training duration was associated with lower central arterial stiffness (cSBP: p = 0.001; aPWV: p = 0.033) and improved AC (p < 0.001). Higher training intensity was related to improved AC (p < 0.001) and larger carotid diameter (p = 0.040). Boys presented thicker cIMT (p = 0.010), improved AC (p = 0.006), and lower central arterial stiffness (cSBP: p < 0.001; aPWV: p = 0.016) associated with higher training duration. Girls presented improved AC (p = 0.023) and lower Ep (p = 0.038) but higher β (p = 0.036) associated with higher training duration. Only boys demonstrated thicker cIMT (p = 0.016) and improved AC (p = 0.002) associated with higher training intensity. A quintile analyses of the training duration revealed thicker cIMT of children and adolescents in Q1 and Q5 than that in Q4 and Q5. Besides, Q1 showed lower cSBP compared to Q4 and Q5. Regarding training intensity, Q5 had thicker cIMT than Q2 and Q3. Although a higher training load is associated with thicker cIMT, the common carotid artery is also more elastic. This suggests that a higher training load leads to a functional adaptation of the carotid artery in youth.

Vascular diameter and intima-media thickness to diameter ratio values of the carotid artery in 642 healthy children

In children, arterial alterations occur with increased intima-media thickness as well as vascular diameter enlargement. Both conditions correlate with higher cardiovascular risk in adults, and both the array and proportion of these alterations are important hemodynamic parameters. In terms of functional adaptation processes, they influence several arterial wall properties as for example the shear and tensile stress of the vessel. There are no reference values for the vascular diameter and intima-media thickness/diameter ratio of the carotid artery in children. Therefore, this study aimed to assess vascular diameter, intima-media thickness/diameter ratio and related tensile stress values in children and to further investigate the influence of sex, age, body mass index, and blood pressure. The parameters were measured with high-resolution semi-automated ultrasound. Sex- and age-dependent values were calculated with the LMS method for a cross-sectional sample of 642 healthy, non-obese children aged 8-17 years. The mean vascular diameter was 5.45 ± 0.46 mm; the median intima-media thickness/diameter ratio was 0.085 (0.079-0.092); the median tensile stress was 105.4 (95.2-116.4) kPa. The vascular diameter and the tensile stress were higher, and the intima-media thickness/diameter ratio was lower in boys than in girls. In comparison to the normal weight study population the excludedobese children had a significantly higher diameter, a lower intima-media thickness/diameter ratio, and a higher tensile stress. In multiple regression analyses of diameter, intima-media thickness/diameter ratio, and tensile stress, all parameters were influenced by sex and body mass index. Furthermore, systolic and diastolic blood pressure significantly influenced the vascular diameter, and systolic blood pressure significantly influenced the intima-media thickness/diameter ratio. Conclusion: This study is the first to report values for the diameter, the intima-media thickness/diameter ratio of the carotid artery, and the related tensile stress allowing a more differentiated view of cardiovascular adaptations as it combines structural and functional vascular parameters. What is known: • Intima-media thickness and vascular diameter are related to a higher cardiovascular risk in adults • The intima-media thickness/diameter ratio gives information about hemodynamic and functional vessel adaptation What is new: • Values for vascular diameter, intima-media thickness/diameter ratio, and tensile stress of the carotid artery in children are presented in this study • Intima-media thickness as a surrogate marker for arterial health in children should be complemented by intima-media thickness/diameter ratio measurement.

Carotid IMT and Stiffness in the KiGGS 2 National Survey: Third-Generation Measurement, Quality Algorithms and Determinants of Completeness

Carotid intima-media thickness (cIMT) and carotid stiffness (CS) are important markers of atherosclerotic risk in the young. We assessed a novel third-generation method for its applicability in large population-based epidemiologic studies to determine strengths, limitations, completeness and predictors of unsuccessful measurement. Four thousand seven hundred ninety-eight 14- to 31-y-old participants of the German KiGGS cohort, which is based on a nationally representative sample with 11-y follow-up, underwent B-mode ultrasound examinations of the left and right common carotid artery with semi-automatic edge detection and automatic electrocardiogram-gated real-time quality control based on a sophisticated snake algorithm and subpixel interpolation. Overall completeness was 98% for far wall cIMT and 89% for CS parameters. Plane-specific completeness varied from 92%-96% for far wall and from 64%-69% for near-wall cIMT. Obesity independently predicted unsuccessful cIMT and CS measurements with odds ratios of 12.67 (95% confidence interval: 5.50-29.19) and 7.30 (4.87-10.94) compared with non-overweight after adjustment for blood pressure, cholesterol, smoking, hazardous drinking, age, sex and sonographer. Inter- and intra-rater reliabilities of cIMT and CS parameters in a sample of 15 young adults were good or excellent. Third-generation cIMT and CS measurements in the young with semi-automatic edge-detection and automatic real-time quality control has been successfully standardized with high reliability and very high completeness in a national survey setting. This provides a strong methodological foundation for further validation of the predictive value of cIMT and CS for atherosclerotic risk in the young.

Vascular Structure and Function in Children and Adolescents: What Impact Do Physical Activity, Health-Related Physical Fitness, and Exercise Have?

A physically active lifestyle can prevent cardiovascular disease. Exercise intervention studies in children and adolescents that aim to increase physical activity have resulted in reduced vascular wall thickening and improve cardiovascular function. Here we review the literature that explores the correlations between physical activity, health-related physical fitness, and exercise interventions with various measures of vascular structure and function in children and adolescents. While several of these studies identified improvements in vascular structure in response to physical activity, these associations were limited to studies that relied on questionnaires. Of concern, these findings were not replicated in studies featuring quantitative assessment of physical activity with accelerometers. Half of the studies reviewed reported improved vascular function with increased physical activity, with the type of vascular measurement and the way physical activity was assessed having an influence on the reported relationships. Similary, most of the studies identified in the literature report a beneficial association of health-related physical fitness with vascular structure and function. Overall, it was difficult to compare the results of these studies to one another as different methodologies were used to measure both, health-related physical fitness and vascular function. Likewise, exercise interventions may reduce both arterial wall thickness and increased vascular stiffness in pediatric populations at risk, but the impact clearly depends on the duration of the intervention and varies depending on the target groups. We identified only one study that examined vascular structure and function in young athletes, a group of particular interest with respect to understanding of cardiovascular adaptation to exercise. In conclusion, future studies will be needed that address the use of wall:diameter or wall:lumen-ratio as part of the evaluation of arterial wall thickness. Furthermore, it will be critical to introduce specific and quantitative measurements of physical activity, as intensity and duration of participation likely influence the effectiveness of exercise interventions.

Primary Prevention: No Associations of Strength and Cardiorespiratory Fitness Status With Arterial Stiffness in Young School Children

Pulse wave velocity (PWV) and central systolic blood pressure (CSBP) are well-established biomarkers of arterial stiffness. Further, fitness is known to be an important protective factor in adults in respect of vascular stiffening. However, the association of both muscular and cardiorespiratory fitness (CRF) with arterial properties in younger individuals has been inconsistent. The aim of the present study was to investigate the relationship between anthropometric data, CRF, strength status, and arterial stiffness parameters in German primary school children. A total of 76 children, age 6-11 years (63.2% males) were examined. Peripheral systolic blood pressure (PSBP) [mmHg] and peripheral diastolic blood pressure (PDBP) [mmHg] and PWV [m/s] were measured non-invasively after 10 min of rest with the oscillometric cuff-based Mobil-O-Graph (IEM, Healthcare, Stolberg, Germany). CSBP [mmHg] was calculated using the ARCSolver Algorithm (Austrian Institute of Technology, Vienna, Austria) based on the recorded brachial pulse waves. CRF was measured using the validated Progressive Aerobic Cardiovascular Endurance run (PACER), also called shuttle-run test, for estimating maximal aerobic capacity (VO_2max). Hand-grip strength as an indicator of overall muscle strength was determined with the Jamar Analog Hand Dynamometer. The results were recorded in kilograms [kg]. For more detailed analyses, the study group was divided into subcohorts, namely a risk group including children with abnormal blood pressure or high body weight, and a healthy subgroup. Healthy children showed a positive association between PWV and body mass index (BMI) (p = 0.016) and CSBP and BMI (p = 0.033), respectively. Hand-grip strength was positively associated with CSBP (left: p = 0.013, right: p = 0.015) and PWV (left: p = 0.008, right: p = 0.002), as well as the number of shuttle run rounds were positively correlated to PWV (p = 0.038) in the whole cohort. No significant association of converted VO2max with arterial PWV was found. The multivariate regression analysis explained 38.8% (R ² = 0.388) of the variance and the model was a significant predictor of PWV [F _{(6, 29)} = 3.060, p = 0.019], however, none of the integrated covariates (BMI, number of shuttle run rounds, VO_2max, dominant hand-grip strength) contributed significantly to the model. The lack of associations between fitness, strength and arterial stiffness might be explained by the few harmful lifestyle factors influencing vascular changes in the first decade of life.

Exercise-associated prevention of adult cardiovascular disease in children and adolescents: monocytes, molecular mechanisms, and a call for discovery

Atherosclerosis originates in childhood and adolescence. The goal of this review is to highlight how exercise and physical activity during childhood and adolescence, critical periods of growth and development, can prevent adult cardiovascular disease (CVD), particularly through molecular mechanisms of monocytes, a key cell of the innate immune system. Monocytes are heterogeneous and pluripotential cells that can, paradoxically, play a role in both the instigation and prevention of atherosclerosis. Recent discoveries in young adults reveal that brief exercise affects monocyte gene pathways promoting a cell phenotype that patrols the vascular system and repairs injuries. Concurrently, exercise inhibits pro-inflammatory monocytes, cells that contribute to vascular damage and plaque formation. Because CVD is typically asymptomatic in youth, minimally invasive techniques must be honed to study the subtle anatomic and physiologic evidence of vascular dysfunction. Exercise gas exchange and heart rate measures can be combined with ultrasound assessments of vascular anatomy and reactivity, and near-infrared spectroscopy to quantify impaired O2 transport that is often hidden at rest. Combined with functional, transcriptomic, and epigenetic monocyte expression and measures of monocyte-endothelium interaction, molecular mechanisms of early CVD can be formulated, and then translated into effective physical activity-based strategies in youth to prevent adult-onset CVD.

Influence of Vigorous Physical Activity on Structure and Function of the Cardiovascular System in Young Athletes-The MuCAYA-Study

Objective: Moderate physical activity (PA) is associated with a reduced risk to develop cardiovascular disease. However, junior athletes exercise between 10 and 20 h a week with intensities exceeding moderate levels by far. In this regard, the cardiovascular system has to increase its work five to six times compared to moderate intensities. This may result in potentially pathological adaptations of the cardiovascular system. The underlying process of vascular adaptations to exercise is yet not fully understood and hardly investigated in junior athletes. An increased blood pressure and pulse wave velocity, ventricular hypertrophy, arrhythmia, and even sudden cardiac death (SCD) has been reported in adult athletes. Studies, examining the cardiovascular system in children, its association to intensity and type of exercise, are rare. Therefore, we present the study protocol of a prospective cross-sectional study that investigates the influence of PA on the cardiovascular system in young athletes.

Methods and Design: Children and adolescents, 7–18 years, presenting for their annual pre-participation screening at the Institute of Preventive Pediatrics, Faculty of Sports and Health Sciences, Technical University of Munich (TUM), are examined in this prospective cross-sectional study. Vascular parameters measured by ultrasound are carotid intima-media thickness (cIMT), vascular stiffness (AC, Ep, β, PWV β), and the vascular diameter (D) to calculate the IMT:Diameter-Ratio (IDR). Cardiac function is evaluated by a 12-lead ECG, and echocardiographic parameters (end-diastolic left ventricular diameter, left ventricular diastolic posterior wall thickness, diastolic septal thickness, left ventricular mass and relative wall thickness, ejection fraction, and shortening fraction). A cardiopulmonary exercise test is performed on a bicycle ergometer, muscular strength is assessed with the handgrip test, and physical activity with the MoMo questionnaire.

Discussion: It is essential to follow young athletes over the course of their career in order to detect pathophysiological changes in the myocardium as soon as possible. If these changes are preceded or followed by changes in vascular structure and function is not known yet. Therefore, we present the study protocol of the Munich Cardiovascular adaptations in young athletes study (MuCAYA-Study) which investigates the association between vascular and cardiac adaptation to intensive exercise in junior athletes.

Functional outcomes in children with anatomically repaired transposition of the great arteries with regard to congenital ventricular septal defect and coronary pattern

OBJECTIVE

Despite decreasing mortality, functional impairments in children with transposition of the great arteries (TGA) are still a concern. This study analyses health-related physical fitness (HRPF), arterial stiffness and health-related quality of life (HRQoL) in children with anatomically repaired TGA regarding congenital ventricular septal defect (VSD) and coronary patterns.

PATIENTS AND METHODS

68 children with anatomically repaired TGA with or without VSD (12.9±3.7 years, 19.1% female) were investigated between August 2014 and October 2017. HRPF was assessed by five tests of the FITNESSGRAM, arterial stiffness was measured by oscillometric measurement using Mobil-O-Graph and HRQoL was analysed with a self-report questionnaire (KINDL-R). All test results were compared with a healthy reference cohort (n=2116, 49.1% female) adjusted for sex and age.

RESULTS

Children with anatomically repaired TGA had significantly worse HRPF (z-score: -0.58±0.81, p<0.001), increased pulse wave velocity (TGA: 4.9±0.3 m/s vs healthy: 4.8±0.3 m/s, p=0.028) and central systolic blood pressure (TGA: 105.9±5.8 mm Hg vs healthy: 103.3±5.7 mm Hg, p=0.001). No difference was found for HRQoL between the two groups (total HRQoL score: TGA: 76.5±10.2 vs healthy: 75.2±10.1, p=0.315). Neither the coronary pattern nor a congenital VSD resulted in significant differences in all functional outcomes.

CONCLUSION

Children with anatomically repaired TGA exhibit impaired HRPF and increased arterial stiffness whereas their HRQoL is normal. The underlying coronary pattern seems to have no influence on the functional outcome, nor does an accompanied congenital VSD.

Functional outcome in contemporary children and young adults with tetralogy of Fallot after repair

OBJECTIVE

Functional outcome measures are of growing importance in the aftercare of patients with congenital heart disease. This study addresses the functional status with regard to exercise capacity, health-related physical fitness (HRPF) and arterial stiffness in a recent cohort of children, adolescents and young adults with tetralogy of Fallot (ToF) after repair.

DESIGN

Single-centre, uncontrolled and prospective cohort study.

SETTING

Outpatient department of the German Heart Centre Munich; July 2014-January 2018.

PATIENTS

One hundred and six patients with ToF after repair (13.5±3.7 years, 40 females) were included. Data were compared with a recent cohort of healthy controls (HCs) (n=1700, 12.8±2.6 years, 833 females).

MAIN OUTCOME MEASURES

Patients underwent a symptom-limited cardiopulmonary exercise test, performed an HRPF test (FitnessGram) and had an assessment of their arterial stiffness (Mobil-O-Graph).

RESULTS

Compared with HC, patients with ToF showed lower predicted [Formula: see text]O₂ peak (ToF: 80.4% ± 16.8% vs HC: 102.6% ± 18.1%, p<0.001), impaired ventilatory efficiency (ToF: 29.6 ± 3.6 vs HC: 27.4 ± 2.9, p<0.001), chronotropic incompetence (ToF: 167 ± 17 bpm vs HC: 190 ± 17 bpm, p<0.001) and reduced HRPF (ToF z-score: -0.65 ± 0.87 vs HC z-score: 0.03 ± 0.65, p<0.001). Surrogates of arterial stiffness, central and peripheral systolic blood pressure, did not differ between the two groups.

CONCLUSIONS

Contemporary children, adolescents and young adults with ToF still have functional limitations. How impaired HRPF and limited exercise capacity interact and how they can be modified needs to be evaluated in further intervention studies.

Health-Related Physical Fitness and Quality of Life in Children and Adolescents With Isolated Left-to-Right Shunt

Objective: Atrial (ASD) and ventricular septal defects (VSD) represent the most common congenital heart defects (CHD) and are considered simple and curable. This study investigates long-term functional outcomes in children with such defects. Patients and Methods : We examined 147 patients (74 girls, 12.1 ± 3.5 years) with isolated shunts (ASD: 54%, VSD: 46%) for their Health-Related Physical Fitness (HRPF) and Health-Related Quality of Life (HRQoL). Native condition was present in 58 patients, interventional closure of the defect was performed in 42 and surgical closure in 47. For comparison, a healthy control group (CG) of 1,724 children (48.9% girls, 12.8 ± 2.8 years) was recruited within two recent school projects. Results: After adjustment for age and sex, children with ASD and VSD presented lower HRPF (z-score healthy peers: 0.02 ± 0.73, ASD: -0.41 ± 0.73, p < 0.001; VSD: -0.61 ± 0.73, p < 0.001) then healthy peers. Transferred into percentiles, VSD were on the 26th and ASD on the 34th percentile of the healthy peers. HRQoL did not differ between peers and CHD with isolated shunts (healthy peers: 76.1 ± 9.7, ASD: 76.2 ± 9.9, p = 0.999; VSD: 78.7 ± 9.7, p = 0.316). Regarding the surgical history of the shunts (native, percutaneously treated, surgically treated), there were also no difference in-between these three states, nor differed HRPF and HRQoL in-between gender. Conclusions: Children with ASD or VSD have impaired HRPF but normal HRQoL. Early childhood sports promotion could be a good measure to counteract these restrictions in HRPF at an early stage.