Open access peer-reviewed chapter - ONLINE FIRST

The Role of Cardiorespiratory Fitness in Children with Cardiovascular Risk

Written By

Mirjam Močnik and Nataša Marčun Varda

Submitted: March 20th, 2022 Reviewed: March 28th, 2022 Published: April 26th, 2022

DOI: 10.5772/intechopen.104701

IntechOpen
Cardiorespiratory Fitness - New Topics Edited by Hasan Sözen

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Cardiorespiratory Fitness - New Topics [Working Title]

Dr. Hasan Sözen

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Abstract

Cardiorespiratory fitness is an outcome of physical activity, enabling the transport of oxygen from the atmosphere to the mitochondria to perform physical work and therefore reflects the overall capacity of the cardiovascular and respiratory systems to perform the prolonged exercise. In recent decades, it has declined in the paediatric population. Cardiovascular fitness measurement has yet to be standardised in children but is a powerful marker of health in youth and is strongly associated with inflammation and inversely associated with cardiovascular risk factors, especially obesity. Notably, youth with low cardiorespiratory fitness levels have a higher risk of developing cardiovascular diseases during adulthood. Lowered cardiorespiratory fitness has been demonstrated most often in children with obesity and associated cardiovascular comorbidities, however, these can be associated with cardiorespiratory fitness independently to body mass index. The benefits of physical activity on health have been well demonstrated during growth and it should be encouraged in children with cardiovascular risk to prevent further reduction of cardiorespiratory fitness and the development of other comorbidities. Along with appropriate physical exercise and diet in childhood, breastfeeding in the first year of life is recommended.

Keywords

  • cardiorespiratory fitness
  • children
  • obesity
  • traditional cardiovascular risk
  • novel cardiovascular risk

1. Introduction

Cardiorespiratory fitness presents individuals’ ability to transport oxygen from the atmosphere to the mitochondria to perform physical work and therefore reflects the overall capacity of the cardiovascular and respiratory systems to perform prolonged exercise [1]. Cardiovascular fitness is therefore reflected in the ability of physical activity, which is critical in childhood as it lays the foundations for later physical activity – the base on which children can build more specific motor skills or develop movement patterns [2].

Epidemiologically, physical activity has been decreasing in the last decades [2], even more before the year of 2000, after which the trend stabilised with negligible changes [3] apart from COVID-19 epidemics, where cardiorespiratory fitness declined significantly [4, 5]. The decline in the last decades was more pronounced in children over the school-age years. Boys were usually more fit than girls [6]. Cardiorespiratory fitness was found to be higher in socially advantaged children [7].

Lower cardiorespiratory fitness is associated with low physical activity and increased fat mass. Increasing obesity in children is therefore strongly inversely associated with cardiorespiratory fitness and indicates reduced physical activity in the paediatric population in recent decades. Interestingly, fitness scores also decreased among lean children [8]. Association between low cardiorespiratory fitness and metabolic risk factors might therefore be only partially mediated through obesity [9]. Sedentary time also negatively affects cardiorespiratory fitness [10], which is independently linked to poor metabolic health [10]. Physical activity and sedentary time are clearly interrelated but a reciprocal relationship between them cannot be assumed [11]. Physical activity and training undoubtedly improve cardiovascular fitness with high-intensity interval training being more successful in enhancing cardiovascular fitness compared to moderate-intensity continuous training [12].

Cardiorespiratory fitness has been also associated with inflammatory biomarkers in children with a positive association with body fat. Similarly, the association between lifestyle behaviours, such as diet, physical activity and sedentary behaviour, and inflammation were found in the paediatric population [13].

Improved cardiorespiratory fitness was associated with the reduced inflammatory profile, independently of body composition and lifestyle behaviours [13]. Cardiorespiratory fitness and sports-related physical activity were also inversely associated with arterial stiffness in young adults [14].

Low cardiorespiratory fitness is strongly associated with the clustering of cardiovascular risk factors in children [15]. Evaluation and improvement of cardiorespiratory fitness in children with cardiovascular risk factors might be associated with improved health parameters in later life [1]. In this review, we present methods on how to evaluate cardiovascular fitness in children along with available data on cardiovascular fitness in children with some traditional and novel cardiovascular risk factors. Some specific strategies to improve cardiovascular fitness in children are also added.

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2. Cardiorespiratory fitness in children: how to measure it?

Cardiorespiratory fitness was clearly associated with body mass index, fat mass, and metabolic syndrome development, however, other cardiovascular risk factors are not always convincing in the literature. Partly, this might be the result of the different evaluation of cardiovascular fitness in different studies [16]. The barriers to cardiovascular fitness assessment include the lack of standardisation in the test protocols, the health outcome being evaluated as well as the absence of evidence-based clinical cut points at these ages [17].

The most widely used indicator of cardiorespiratory fitness is the volume of oxygen that is consumed at maximal physical exertion (VO2max), measured from the respiratory gas exchange by indirect calorimetry [18]. It can be objectively and accurately measured through laboratory tests such as progressive run or cycle, however, these protocols require sophisticated equipment (run/cycle ergometer tests with respiratory gas analysis), the availability of trained technicians, making these tests expensive and time-consuming. Alternatively, field tests are more appropriate for universal screening and include a 550-m timed run/walk or “Maximal Multistage 20-m Shuttle Run Test” [18]. The latter was identified as the most scalable and reliable field test, where VO2max can be predicted by special equations [19, 20]. For a field test to be valid it is required to accurately and reliably measure what it claims to measure, however, field-based tests usually suffer from low relative validity when compared to VO2max measurement and are producing conflicting results [18, 21]. Other similar screening tests are being developed, such as the 3-minute Kasch Pulse Recovery Test, where a reference range for the classification of cardiorespiratory fitness was developed on the basis of the age-specific percentile distribution of heart rate after exercise in 6- to 9- and 10- to 12-year-old children. The value of heart rate after exercise is considered an indicator of cardiorespiratory fitness [22].

Another obstacle in the cardiorespiratory fitness evaluation is the lack of age-specific cut-off points for increased cardiovascular risk. They were attempted to be set by a systematic review in children aged 8–19 years that determined that fitness levels below 42 and 35 mL/kg/min (VO2max measurement) for boys and girls, respectively, should raise a red flag. These cut-points identify children and adolescents who may benefit from primary and secondary cardiovascular prevention programming [17]. Similarly, a study using a 20-m Shuttle Run Test with VO2max prediction by estimation revealed cut-off points in 8- to 12-year-olds for obesity identified as 39 mL/kg/min and 41 mL/kg/min for girls and boys, respectively [23].

Recommendations for future research must include standardised measurements with standardised outcome assessments of cardiorespiratory fitness. For universal screening, a field test approach might be more appropriate, however, in children with cardiovascular risk, or suboptimal results in the field test, a more accurate approach might be more appropriate with cut-off points determined for gender and age.

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3. Cardiorespiratory fitness in children with obesity

Children with obesity have lower cardiorespiratory fitness than normal-weight children [24], which is more pronounced in girls [25] and is commonly associated with reduced physical activity [26]. Body mass index also mediates the association between cardiorespiratory fitness and metabolic syndrome in schoolchildren. Higher levels of cardiorespiratory fitness are associated with lower cardiometabolic risk, particularly, when accompanied by weight reduction [27]. Lower cardiorespiratory fitness in children with obesity was associated with overall and abdominal fat mass, whereas both central and total obesity were lower in overweight and obese children with high cardiorespiratory fitness [28, 29, 30]. There is extensive evidence to support the fat-but-fit paradigm, which shows that cardiorespiratory fitness can counteract the adverse effects of obesity on cardiovascular risk factors. Unfit children with obesity had exaggerated systolic blood pressure at rest and during sympathetic activation, presumably coupled with higher cardiac output and cardiac oxygen demand [31]. Even from the molecular point of view, fit children with obesity or overweight had a distinct pattern of whole-blood gene expression [32]. Concerning the autonomic nervous system’s role, greater parasympathetic cardiac activity was associated with higher levels of cardiorespiratory fitness in both girls and boys, while the sympathetic-vagal balance was negatively related to maximal oxygen uptake in girls [33].

Additionally, in obesity, low-grade chronic inflammation and homeostatic stress produced mainly in adipocytes can result in abnormal adipokine secretion, which could be involved in the pathogenesis of lowered cardiorespiratory fitness. The secretion of adipokines is also influenced by physical fitness. It has been demonstrated that in children with obesity, VO2max can be predicted from haematological parameters, such as leptin and fibrinogen [34].

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4. Cardiorespiratory fitness in children with other traditional cardiovascular risk

4.1 Cardiorespiratory fitness in children with hypertension

Obesity-related hypertension is a problem on the rise with obesity epidemics. Cardiorespiratory fitness was associated with total and central obesity as well as hypertension [35, 36]. Systolic and diastolic blood pressure showed curvilinear relation with cardiorespiratory fitness along with waist circumference and the sum of skinfolds [37]. However, regardless of obesity, cardiorespiratory fitness in children has been associated with other metabolic risk factors and future health. Teenagers with low cardiorespiratory fitness were more likely to develop hypertension in adulthood, even among participants with a normal body mass index [24]. Children who are fit and participate regularly in sports outside school hours are less likely to be hypertensive [38]. Long-term low levels of cardiorespiratory fitness exhibited the highest levels of systolic blood pressure [39]. The combination of a family history of hypertension and cardiorespiratory fitness also showed a clear association with the increased risk of hypertension [40]. Interestingly, some studies set a different perspective on cardiorespiratory fitness and hypertension, somehow contradicting the above-mentioned associations. In one of them, physical activity was not associated with systolic blood pressure independently of adiposity, but there was a small independent association only with diastolic blood pressure [41]. Another study demonstrated that adolescents with overweight or obesity have a higher prevalence of higher blood pressure, regardless of cardiorespiratory fitness, suggesting that maintaining a normal body mass index protects against less favourable blood pressure [42]. Anyway, a study published two decades ago demonstrated that the level of cardiorespiratory fitness did not seem to be an important correlate of blood pressure variation across age groups and gender in schoolchildren [43].

4.2 Cardiorespiratory fitness in children with dyslipidaemia

Abnormal lipid profile is commonly known as a cardiovascular risk factor, sometimes associated with obesity, but in children, it can be the consequence of genetic defect leading to familial hypercholesterolemia also in lean children [44]. However, specific studies regarding familial hypercholesterolemia and cardiorespiratory fitness are lacking in the paediatric population. Overall, evidence supports an inverse association between cardiorespiratory fitness and dyslipidaemia with expected improvements in high-density lipoprotein cholesterol with exercise, which is the most consistent finding. The findings regarding the effects of exercise training on other lipid components have been variable, with both positive and null results, but in general demonstrate a reduction of total cholesterol and triglycerides with exercise training [45, 46]. Future studies in the paediatric population are needed to clarify the association between cardiorespiratory fitness change and dyslipidaemia [45].

4.3 Cardiorespiratory fitness in children with diabetes mellitus type 1 or type 2

Lower cardiorespiratory fitness, strength, and higher central adiposity were also highly predictive of higher levels of insulin resistance in children and adolescents without diabetes mellitus [47], however, at least in part, are mediated through obesity [48]. Nevertheless, increased muscle strength and cardiorespiratory fitness were associated with decreased insulin resistance and improved 𝛽-cell function among young in population studies [49, 50]. Cardiorespiratory fitness and muscular fitness in children are not only important in childhood but it was proven that they were inversely associated with measures of fasting insulin, insulin resistance, and 𝛽-cell function in adulthood [51].

In children with already developed diabetes mellitus, cardiorespiratory fitness might play an even more pivotal role. Independently of obesity, there was a significant inverse relationship between cardiorespiratory fitness and lipid profile components and systolic blood pressure in children with poorly controlled type 1 diabetes mellitus, indicating a favourable effect of increased cardiorespiratory fitness [52]. Additionally, youth with diabetes mellitus type 1 who are physically active, tend to have lower glycated haemoglobin and reduced insulin needs. Also, activity in adolescents at-risk for diabetes mellitus type 2 improves various measures of metabolism and body composition [53]. In children with diabetes mellitus type 2, lower levels of cardiorespiratory fitness were observed mostly due to physical inactivity [54]. People with diabetes mellitus type 2 have reduced cardiorespiratory fitness compared to healthy controls, with an association to increased cardiovascular morbidity and mortality. The mechanisms of lower cardiorespiratory fitness in children with diabetes mellitus type 2 are multifaceted and involve interrelated defects in insulin action, mitochondrial dysfunction, skeletal muscle microvasculature, and cardiac dysfunction [55]. In youth with diabetes mellitus type 2, left ventricular size is clearly related to physical fitness, which might counteract adverse effects of poor glycaemic control and, at least according to the study, right ventricular function [56]. Regular physical activity is an important component in the management of both diabetes mellitus type 1 and type 2, as it has the potential to improve glycaemic control, delay cardiovascular complications, and increase overall well-being [57].

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5. Cardiorespiratory fitness in children with novel cardiovascular risk

5.1 Cardiorespiratory fitness in children with chronic kidney disease

Children with chronic kidney disease have lower cardiorespiratory fitness due to various reasons, one of the most important is reduced physical activity and increased sedentary lifestyle mainly due to the renal replacement therapy requirements (e.g. haemodialysis) [58]. Additionally, chronic kidney disease is associated with anaemia, effects of chronic uraemia, and metabolic acidosis on the heart and skeletal muscle, all contributing significantly to reduce physical activity [59]. Paediatric patients with chronic kidney disease are therefore significantly physically inactive, with less than 10% of the non-school time being physically active [60]. Additionally, children after kidney transplantation significantly gained fat weight [60, 61]. One of the reasons after transplantation might also be related to sirolimus effects on skeletal muscle [61]. Reduced cardiorespiratory fitness was strongly associated with the clustering of cardiovascular risk factors in these children [62].

Studies suggest that regular and early implementation of both aerobic and resistance exercise programs in persons with chronic kidney disease have positive effects on muscle function, exercise tolerance, and quality of life [59]. In children with a successful renal transplant, a weekly physical exercise of 3−5 hours significantly improved cardiorespiratory fitness and left ventricular mass [63].

In children with a congenital single kidney, physical activity improved aerobic capacity and exercise tolerance without increasing the risks of cardiovascular accidents [64], however, in the patients contact sports might be discouraged due to the increased risk of sport-related injury.

5.2 Cardiorespiratory fitness in children born prematurely

Children and also later adults, born prematurely, are likely to have poorer cardiorespiratory fitness, however, according to some studies, the poor cardiorespiratory outcome of a child born prematurely is not firmly established [65, 66]. In adults, exercise capacity was only modestly reduced and frequently with values within a normal range and was consistent with self-reported exercise capacity [67]. In addition, in children with abnormal lung function and structure, this did not impact the aerobic exercise capacity of preterm children at school age [68]. On the contrary, Welsh et al. demonstrated a significant reduction in peak oxygen consumption among prematurely born children but with no difference in physical activity [69]. Some subgroups of premature-born individuals might be at increased risk for reduced cardiorespiratory fitness, especially those with lower muscular fitness, which was more common among premature-born young adults [70]. Lowered muscle strength is associated also with neuromotor sequelae of premature birth [71]. Another risk factor for reduced exercise capacity is also a decreased ventricular size and mass that might be a consequence of prematurity [72]. Impaired heart rate recovery after maximal exercise might also play a role in poor cardiorespiratory fitness in some suggesting an impaired development of autonomic nervous function after preterm labour [73].

Babies, born prematurely, are a diverse group of patients with complications that depend on several factors, such as gestational age, associated comorbidities, prenatal factors, postnatal care, etc. Therefore, the studies are diverse and might contradict each other because the effect of premature birth depends on so many other factors. Anyway, children born prematurely do have a risk for lowered cardiorespiratory fitness and regular physical intervention is believed to produce better outcomes [65, 71].

5.3 Cardiorespiratory fitness in children with congenital heart disease

Congenital heart disease may in a variety of ways adversely affect hemodynamic responses, usually produced during exercises, such as increased heart rate, preload, and heart contractility with decreased systemic vascular resistance and pulmonary vascular resistance [74]. Therefore, the consequences of cardiorespiratory fitness depend on the congenital defect itself and a proper evaluation is of pivotal importance to evaluate cardiac rehabilitation. Historically, children with congenital heart disease have been restricted from exercise, contributing to a sedentary lifestyle as well as increased cardiovascular risk factors. Given the large benefits and small risks of exercise in this population, guidelines have recently shifted towards exercise promotion [75]. In children, several tests to evaluate cardiorespiratory fitness might be used [74], however, the 6-minute walk test is quite common and was found to be a useful and reliable tool in the assessment and follow-up of functional capacity during rehabilitation programs [76]. Furthermore, exercise training is safe and beneficial for the vast majority of adults with congenital heart disease following appropriate screening [77, 78].

Exercise recommendations should be individualised based on functional parameters using a structured methodology to approach the evaluation, risk classification, and prescriptions of exercise and physical activity [75]. Participation in aerobic exercise significantly increased the quality of life in children with congenital heart disease [79].

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6. Cardiorespiratory fitness, sleep and psychosocial well-being

Sleeping quality was also associated with cardiorespiratory fitness, not necessarily in children with high body mass index, as might be expected. Girls who were classified as fit were more likely to report better sleep quality compared to their unfit peers. Poor sleep quality was associated with lower cardiorespiratory fitness with no significant association with body mass index [80].

Not only obesity reduction, but improved cardiorespiratory fitness also positively affects psychosocial well-being, leading to improved self-esteem and reduced stress, further reducing cardiovascular risk. Cognitive function and cardiorespiratory fitness correlate significantly and are predictors of psychological well-being among school-aged children. In addition, students with a higher level of psychological well-being showed a higher cardiorespiratory fitness, concentration performance, and attention accuracy [81]. Cardiorespiratory fitness also had a small protective effect against developing depression [82]. Similarly, it was found that stress and depression can affect an individual’s level of physical activity and fitness, which may place them at risk of developing cardiovascular disease, confirming the role of increased physical activity in improving depression and reducing depression-related stress to improve cardiovascular risk [83].

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7. Strategies to improve cardiorespiratory fitness in children

Addressing cardiovascular fitness in children and adolescents could reduce future adiposity, improve other cardiovascular risk factors and thus be an important factor in improving health [16]. The main strategies for reducing cardiovascular risk and obesity remain physical exercise with a reduced sedentary lifestyle and an appropriate diet. Promoting health-related cardiorespiratory fitness in physical education proved to be an important contributor to improving cardiorespiratory fitness in children. Intensity, age, and weight status importantly affect cardiorespiratory fitness [84]. In children with obesity, regular exercise is even more important, and may not need to be vigorous; recreational programs are also effective and may encourage children to participate in physical activity and limit initial dropout. Three-month training programs in children with obesity led to decreased body mass index, waist circumference, decreased fat mass, blood glucose, homeostasis model assessment for insulin resistance, triglycerides, and systolic pressure before and after exercise [85].

A healthier diet in preschool and schoolchildren also led to lower adiposity levels, lower waist circumference, and increased cardiorespiratory fitness, making it a relevant modifiable factor in obesity management [86, 87].

The management of the whole family is of utmost importance because a parent's effect can have a significant impact on children's willingness and motivation to change their lifestyle [88]. Breastfeeding has also been positively associated with cardiorespiratory fitness, where breastfeeding for more than 6 months proved to have positive effects on cardiorespiratory fitness. Therefore, early nutrition may be a predictor for adolescence physical health and is of special importance to promoting healthier lifestyle in children as it is associated with higher cardiorespiratory fitness [89].

Intervention strategies aiming to reduce obesity and improve cardiorespiratory fitness in childhood might contribute to the prevention of metabolic syndrome in adulthood [90]. The process is schematically presented in Figure 1.

Figure 1.

From regular physical activity and diet to decreased morbidity and mortality due to the cardiovascular diseases.

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8. Conclusions

Cardiorespiratory fitness is declining in the paediatric population and is closely associated with increased cardiovascular risk. In children already having a cardiovascular risk factor present, it is important to determine cardiorespiratory fitness and if it is decreased, prompt physical intervention is warranted. Further research is needed to establish a standardised protocol of its measurement. Interventions include increased and customized physical activity along with a healthy diet. In children, breastfeeding could present an additional preventive factor.

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Conflict of interest

The authors declare no conflict of interest.

References

  1. 1. García-Hermoso A, Ramírez-Vélez R, García-Alonso Y, Alonso-Martínez AM, Izquierdo M. Association of cardiorespiratory fitness levels during youth with health risk later in life: A systematic review and meta-analysis. JAMA Pediatrics. 2020;174:952-960. DOI: 10.1001/jamapediatrics.2020.2400
  2. 2. Eberhardt T, Niessner C, Oriwol D, Buchal L, Worth A, Bös K. Secular trends in physical fitness of children and adolescents: A review of large-scale epidemiological studies published after 2006. International Journal of Environmental Research and Public Health. 2020;17:5671. DOI: 10.3390/ijerph17165671
  3. 3. Tomkinson GR, Lang JJ, Tremblay MS. Temporal trends in the cardiorespiratory fitness of children and adolescents representing 19 high-income and upper middle-income countries between 1981 and 2014. British Journal of Sports Medicine. 2019;53:478-486. DOI: 10.1136/bjsports-2017-097982
  4. 4. Jarnig G, Jaunig J, van Poppel MNM. Association of COVID-19 mitigation measures with changes in cardiorespiratory fitness and body mass index among children aged 7 to 10 years in Austria. JAMA Network Open. 2021;4:e2121675. DOI: 10.1001/jamanetworkopen.2021.21675
  5. 5. López-Bueno R, Calatayud J,Andersen LL, Casaña J, Ezzatvar Y, Casajús JA, et al. Cardiorespiratory fitness in adolescents before and after the COVID-19 confinement: A prospective cohort study. European Journal of Pediatrics. 2021;180:2287-2293. DOI: 10.1007/s00431-021-04029-8
  6. 6. Sallis JF. Epidemiology of physical activity and fitness in children and adolescents. Critical Reviews in Food Science and Nutrition. 1993;33:403-408. DOI: 10.1080/10408399309527639
  7. 7. Okely AD, Hardy LL, Booth ML, Dobbins TA, Denney-Wilson EA, Yang B. Changes in cardiorespiratory fitness among children and adolescents in Australia: 1997 and 2004. Journal of Sports Sciences. 2010;28:851-857. DOI: 10.1080/02640411003716959
  8. 8. Stratton G, Canoy D, Boddy LM, Taylor SR, Hackett AF, Buchan IE. Cardiorespiratory fitness and body mass index of 9-11-year-old English children: A serial cross-sectional study from 1998 to 2004. International Journal of Obesity. 2007;31:1172-1178. DOI: 10.1038/sj.ijo.0803562
  9. 9. Ekelund U, Anderssen SA, Froberg K, Sardinha LB, Andersen LB, Brage S, et al. Independent associations of physical activity and cardiorespiratory fitness with metabolic risk factors in children: The European youth heart study. Diabetologia. 2007;50:1832-1840. DOI: 10.1007/s00125-007-0762-5
  10. 10. Moore JB, Beets MW, Barr-Anderson DJ, Evenson KR. Sedentary time and vigorous physical activity are independently associated with cardiorespiratory fitness in middle school youth. Journal of Sports Sciences. 2013;31:1520-1525. DOI: 10.1080/02640414.2013.793378
  11. 11. Sandercock GR, Ogunleye AA. Independence of physical activity and screen time as predictors of cardiorespiratory fitness in youth. Pediatric Research. 2013;73:692-697. DOI: 10.1038/pr.2013.37
  12. 12. Cao M, Quan M, Zhuang J. Effect of high-intensity interval training versus moderate-intensity continuous training on cardiorespiratory fitness in children and adolescents: A meta-analysis. International Journal of Environmental Research and Public Health. 2019;16:1533. DOI: 10.3390/ijerph16091533
  13. 13. González-Gil EM, Santaliestra-Pasías AM, Buck C, Gracia-Marco L, Lauria F, Pala V, et al. Improving cardiorespiratory fitness protects against inflammation in children: The IDEFICS study. Pediatric Research. 2022;91:681-689. DOI: 10.1038/s41390-021-01471-0
  14. 14. Boreham CA, Ferreira I, Twisk JW, Gallagher AM, Savage MJ, Murray LJ. Cardiorespiratory fitness, physical activity, and arterial stiffness: The Northern Ireland Young Hearts Project. Hypertension. 2004;44:721-726. DOI: 10.1161/01.HYP.0000144293.40699.9a
  15. 15. Anderssen SA, Cooper AR, Riddoch C, Sardinha LB, Harro M, Brage S, et al. Low cardiorespiratory fitness is a strong predictor for clustering of cardiovascular disease risk factors in children independent of country, age and sex. European Journal of Cardiovascular Prevention and Rehabilitation. 2007;14:526-531. DOI: 10.1097/HJR.0b013e328011efc1
  16. 16. Mintjens S, Menting MD, Daams JG, van Poppel MNM, Roseboom TJ, Gemke RJBJ. Cardiorespiratory fitness in childhood and adolescence affects future cardiovascular risk factors: A systematic review of longitudinal studies. Sports Medicine. 2018;48:2577-2605. DOI: 10.1007/s40279-018-0974-5
  17. 17. Ruiz JR, Cavero-Redondo I, Ortega FB, Welk GJ, Andersen LB, Martinez-Vizcaino V. Cardiorespiratory fitness cut points to avoid cardiovascular disease risk in children and adolescents; what level of fitness should raise a red flag? A systematic review and meta-analysis. British Journal of Sports Medicine. 2016;50:1451-1458. DOI: 10.1136/bjsports-2015-095903
  18. 18. Hamlin MJ, Fraser M, Lizamore CA, Draper N, Shearman JP, Kimber NE. Measurement of cardiorespiratory fitness in children from two commonly used field tests after accounting for body fatness and maturity. Journal of Human Kinetics. 2014;40:83-92. DOI: 10.2478/hukin-2014-0010
  19. 19. Domone S, Mann S, Sandercock G, Wade M, Beedie C. A method by which to assess the scalability of field-based fitness tests of cardiorespiratory fitness among schoolchildren. Sports Medicine. 2016;46:1819-1831. DOI: 10.1007/s40279-016-0553-6
  20. 20. Léger LA, Mercier D, Gadoury C, Lambert J. The multistage 20 metre shuttle run test for aerobic fitness. Journal of Sports Sciences. 1988;6:93-101. DOI: 10.1080/02640418808729800
  21. 21. Boreham CA, Paliczka VJ, Nichols AK. A comparison of the PWC170 and 20-MST tests of aerobic fitness in adolescent schoolchildren. The Journal of Sports Medicine and Physical Fitness 1990;30:19-23
  22. 22. Jankowski M, Niedzielska A, Brzezinski M, Drabik J. Cardiorespiratory fitness in children: A simple screening test for population studies. Pediatric Cardiology. 2015;36:27-32. DOI: 10.1007/s00246-014-0960-0
  23. 23. Silva DAS, Lang JJ, Barnes JD, Tomkinson GR, Tremblay MS. Cardiorespiratory fitness in children: Evidence for criterion-referenced cut-points. PLoS One. 2018;13:e0201048. DOI: 10.1371/journal.pone.0201048
  24. 24. Johansson L, Brissman M, Morinder G, Westerståhl M, Marcus C. Reference values and secular trends for cardiorespiratory fitness in children and adolescents with obesity. Acta Paediatrica. 2020;109:1665-1671. DOI: 10.1111/apa.15163
  25. 25. Mota J, Flores L, Flores L, Ribeiro JC, Santos MP. Relationship of single measures of cardiorespiratory fitness and obesity in young schoolchildren. American Journal of Human Biology. 2006;18:335-341. DOI: 10.1002/ajhb.20513
  26. 26. Maggio AB, Hofer MF, Martin XE, Marchand LM, Beghetti M, Farpour-Lambert NJ. Reduced physical activity level and cardiorespiratory fitness in children with chronic diseases. European Journal of Pediatrics. 2010;169:1187-1193. DOI: 10.1007/s00431-010-1199-2
  27. 27. Díez-Fernández A, Sánchez-López M, Mora-Rodríguez R, Notario-Pacheco B, Torrijos-Niño C, Martínez-Vizcaíno V. Obesity as a mediator of the influence of cardiorespiratory fitness on cardiometabolic risk: A mediation analysis. Diabetes Care. 2014;37:855-862. DOI: 10.2337/dc13-0416
  28. 28. Nassis GP, Psarra G, Sidossis LS. Central and total adiposity are lower in overweight and obese children with high cardiorespiratory fitness. European Journal of Clinical Nutrition. 2005;59:137-141. DOI: 10.1038/sj.ejcn.1602061
  29. 29. Stigman S, Rintala P, Kukkonen-Harjula K, Kujala U, Rinne M, Fogelholm M. Eight-year-old children with high cardiorespiratory fitness have lower overall and abdominal fatness. International Journal of Pediatric Obesity. 2009;4:98-105. DOI: 10.1080/17477160802221101
  30. 30. Lee SJ, Arslanian SA. Cardiorespiratory fitness and abdominal adiposity in youth. European Journal of Clinical Nutrition. 2007;61:561-565. DOI: 10.1038/sj.ejcn.1602541
  31. 31. Legantis CD, Nassis GP, Dipla K, Vrabas IS, Sidossis LS, Geladas ND. Role of cardiorespiratory fitness and obesity on hemodynamic responses in children. The Journal of Sports Medicine and Physical Fitness. 2012;52:311-318
  32. 32. Plaza-Florido A, Altmäe S, Esteban FJ, Löf M, Radom-Aizik S, Ortega FB. Cardiorespiratory fitness in children with overweight/obesity: Insights into the molecular mechanisms. Scandinavian Journal of Medicine & Science in Sports. 2021;31:2083-2091. DOI: 10.1111/sms.14028
  33. 33. da Silva DF, Bianchini JA, Antonini VD, Hermoso DA, Lopera CA, Pagan BG, et al. Parasympathetic cardiac activity is associated with cardiorespiratory fitness in overweight and obese adolescents. Pediatric Cardiology. 2014;35:684-690. DOI: 10.1007/s00246-013-0838-6
  34. 34. Tsiroukidou K, Hatziagorou E, Grammatikopoulou MG, Vamvakis A, Kontouli K, Tzimos C, et al. Cardiorespiratory fitness predicted by fibrinogen and leptin concentrations in children with obesity and risk for diabetes: A cross-sectional study and a ROC curve analysis. Nutrients. 2021;13:674. DOI: 10.3390/nu13020674
  35. 35. Burgos MS, Reuter CP, Burgos LT, Pohl HH, Pauli LT, Horta JA, et al. Comparison analysis of blood pressure, obesity, and cardio-respiratory fitness in schoolchildren. Arquivos Brasileiros de Cardiologia. 2010;94:788-793. DOI: 10.1590/s0066-782x2010005000046
  36. 36. Ruiz JR, Ortega FB, Loit HM, Veidebaum T, Sjöström M. Body fat is associated with blood pressure in school-aged girls with low cardiorespiratory fitness: The European Youth Heart Study. Journal of Hypertension. 2007;25:2027-2034. DOI: 10.1097/HJH.0b013e328277597f
  37. 37. Klasson-Heggebø L, Andersen LB, Wennlöf AH, Sardinha LB, Harro M, Froberg K, et al. Graded associations between cardiorespiratory fitness, fatness, and blood pressure in children and adolescents. British Journal of Sports Medicine. 2006;40:25-29. DOI: 10.1136/bjsm.2004.016113
  38. 38. Nqweniso S, Walter C, du Randt R, Aerts A, Adams L, Degen J, et al. Prevention of overweight and hypertension through cardiorespiratory fitness and extracurricular sport participation among South African schoolchildren. Sustainability. 2020;12:6581. DOI: 10.3390/su12166581
  39. 39. Agostinis-Sobrinho C, Ruiz JR, Moreira C, Abreu S, Lopes L, Oliveira-Santos J, et al. Cardiorespiratory fitness and blood pressure: A longitudinal analysis. The Journal of Pediatrics. 2018;192:130-135. DOI: 10.1016/j.jpeds.2017.09.055
  40. 40. Gando Y, Sawada SS, Kawakami R, Momma H, Shimada K, Fukunaka Y, et al. Combined association of cardiorespiratory fitness and family history of hypertension on the incidence of hypertension: A long-term cohort study of Japanese males. Hypertension Research. 2018;41:1063-1069. DOI: 10.1038/s41440-018-0117-2
  41. 41. Hunt LP, Shield JP, Cooper AR, Ness AR, Lawlor DA. Blood pressure in children in relation to relative body fat composition and cardio-respiratory fitness. International Journal of Pediatric Obesity. 2011;6:275-284. DOI: 10.3109/17477166.2011.583655
  42. 42. Bertollo C, Barbian CD, de Borba SL, de Castro Silveira JF, Vogt BD, de Mello ED, et al. Hypertension and different levels of body mass index and cardiorespiratory fitness amongst adolescents. International Journal of Cardiovascular Science. 2021;36(6):610-616. DOI: 10.36660/ijcs.20200038
  43. 43. Guerra S, Ribeiro JC, Costa R, Duarte J, Mota J. Relationship between cardiorespiratory fitness, body composition and blood pressure in school children. The Journal of Sports Medicine and Physical Fitness. 2002;42:207-213
  44. 44. Bogsrud MP, Langslet G, Wium C, Johansen D, Svilaas A, Holven KB. Treatment goal attainment in children with familial hypercholesterolemia: A cohort study of 302 children in Norway. Journal of Clinical Lipidology. 2018;12:375-382. DOI: 10.1016/j.jacl.2017.11.009
  45. 45. Reuter CP, Brand C, Silva PTD, Reuter ÉM, Renner JDP, Franke SIR, Met al. Relationship between dyslipidemia, cultural factors, and cardiorespiratory fitness in schoolchildren. Arquivos Brasileiros de Cardiologia 2019;112:729-736. DOI: 10.5935/abc.20190068.
  46. 46. Sui X, Sarzynski MA, Lee DC, Kokkinos PF. Impact of changes in cardiorespiratory fitness on hypertension, dyslipidemia and survival: An overview of the epidemiological evidence. Progress in Cardiovascular Diseases. 2017;60:56-66. DOI: 10.1016/j.pcad.2017.02.006
  47. 47. Benson AC, Torode ME, Singh MA. Muscular strength and cardiorespiratory fitness is associated with higher insulin sensitivity in children and adolescents. International Journal of Pediatric Obesity. 2006;1:222-231. DOI: 10.1080/17477160600962864
  48. 48. Lee S, Bacha F, Gungor N, Arslanian SA. Cardiorespiratory fitness in youth: Relationship to insulin sensitivity and beta-cell function. Obesity (Silver Spring). 2006;14:1579-1585. DOI: 10.1038/oby.2006.182
  49. 49. Grøntved A, Ried-Larsen M, Ekelund U, Froberg K, Brage S, Andersen LB. Independent and combined association of muscle strength and cardiorespiratory fitness in youth with insulin resistance and β-cell function in young adulthood: The European Youth Heart Study. Diabetes Care. 2013;36:2575-2581. DOI: 10.2337/dc12-2252
  50. 50. Artero EG, Ruiz JR, Ortega FB, España-Romero V, Vicente-Rodríguez G, Molnar D, et al. Muscular and cardiorespiratory fitness are independently associated with metabolic risk in adolescents: The HELENA study. Pediatric Diabetes. 2011;12:704-712. DOI: 10.1111/j.1399-5448.2011.00769.x
  51. 51. Fraser BJ, Blizzard L, Schmidt MD, Juonala M, Dwyer T, Venn AJ, et al. Childhood cardiorespiratory fitness, muscular fitness and adult measures of glucose homeostasis. Journal of Science and Medicine in Sport. 2018;21:935-940. DOI: 10.1016/j.jsams.2018.02.002
  52. 52. Miculis CP, de Campos W, Gasparotto GS, Silva MP, Mascarenhas LP, Boguszewski MC. Correlation of cardiorespiratory fitness with risk factors for cardiovascular disease in children with type 1 diabetes mellitus. Journal of Diabetes and its Complications. 2012;26:419-423. DOI: 10.1016/j.jdiacomp.2012.05.011
  53. 53. Pivovarov JA, Taplin CE, Riddell MC. Current perspectives on physical activity and exercise for youth with diabetes. Pediatric Diabetes. 2015;16:242-255. DOI: 10.1111/pedi.12272
  54. 54. Shaibi GQ , Michaliszyn SB, Fritschi C, Quinn L, Faulkner MS. Type 2 diabetes in youth: A phenotype of poor cardiorespiratory fitness and low physical activity. International Journal of Pediatric Obesity. 2009;4:332-337. DOI: 10.3109/17477160902923341
  55. 55. Abushamat LA, McClatchey PM, Scalzo RL, Schauer I, Huebschmann AG, Nadeau KJ, et al. Mechanistic causes of reduced cardiorespiratory fitness in type 2 diabetes. Journal of Endocrine Society. 2020;4:bvaa063. DOI: 10.1210/jendso/bvaa063
  56. 56. Bacha F, Gidding SS, Pyle L, Levitt Katz L, Kriska A, Nadeau KJ, et al. Relationship of cardiac structure and function to cardiorespiratory fitness and lean body mass in adolescents and young adults with type 2 diabetes. The Journal of Pediatrics. 2016;177:159. DOI: 10.1016/j.jpeds.2016.06.048
  57. 57. Nadella S, Indyk JA, Kamboj MK. Management of diabetes mellitus in children and adolescents: Engaging in physical activity. Translation Pediatrics. 2017;6:215-224. DOI: 10.21037/tp.2017.05.01
  58. 58. Clark SL, Denburg MR, Furth SL. Physical activity and screen time in adolescents in the chronic kidney disease in children (CKiD) cohort. Pediatric Nephrology. 2016;31:801-808. DOI: 10.1007/s00467-015-3287-z
  59. 59. Patel DR, Raj VM, Torres A. Chronic kidney disease, exercise, and sports in children, adolescents, and adults. The Physician and Sportsmedicine. 2009;37:11-19. DOI: 10.3810/psm.2009.10.1724
  60. 60. Painter P, Krasnoff J, Mathias R. Exercise capacity and physical fitness in pediatric dialysis and kidney transplant patients. Pediatric Nephrology. 2007;22:1030-1039. DOI: 10.1007/s00467-007-0458-6
  61. 61. Sethna CB, Salerno AE, McBride MG, Shults J, Paridon SM, Sharma N, et al. Cardiorespiratory fitness in pediatric renal transplant recipients. Transplantation. 2009;88:395-401. DOI: 10.1097/TP.0b013e3181aed7d1
  62. 62. Tangeraas T, Midtvedt K, Fredriksen PM, Cvancarova M, Mørkrid L, Bjerre A. Cardiorespiratory fitness is a marker of cardiovascular health in renal transplanted children. Pediatric Nephrology. 2010;25:2343-2350. DOI: 10.1007/s00467-010-1596-9
  63. 63. Lubrano R, Tancredi G, Bellelli E, Gentile I, Scateni S, Masciangelo R, et al. Influence of physical activity on cardiorespiratory fitness in children after renal transplantation. Nephrology, Dialysis, Transplantation. 2012;27:1677-1681. DOI: 10.1093/ndt/gfr434
  64. 64. Tancredi G, Lambiase C, Favoriti A, Ricupito F, Paoli S, Duse M, et al. Cardiorespiratory fitness and sports activities in children and adolescents with solitary functioning kidney. Italian Journal of Pediatrics. 2016;42:43. DOI: 10.1186/s13052-016-0255-6
  65. 65. Ferreira I, Gbatu PT, Boreham CA. Gestational age and cardiorespiratory fitness in individuals born at term: A life course study. Journal of the American Heart Association. 2017;6:e006467. DOI: 10.1161/JAHA.117.006467
  66. 66. Kosiecz A, Chrościńska-Krawczyk M, Taczała J, Zawadka M. Evaluation of physical and cardiorespiratory fitness in 7-year-old prematurely born children − preliminary study. Annals of Agricultural and Environmental Medicine. 2021;28:502-508. DOI: 10.26444/aaem/127220
  67. 67. Clemm HH, Vollsæter M, Røksund OD, Eide GE, Markestad T, Halvorsen T. Exercise capacity after extremely preterm birth. Development from adolescence to adulthood. Annals of the American Thoracic Society. 2014;11:537-545. DOI: 10.1513/AnnalsATS.201309-311OC
  68. 68. O'Dea CA, Logie K, Wilson AC, Pillow JJ, Murray C, Banton G, et al. Lung abnormalities do not influence aerobic capacity in school children born preterm. European Journal of Applied Physiology. 2021;121:489-498. DOI: 10.1007/s00421-020-04530-2
  69. 69. Welsh L, Kirkby J, Lum S, Odendaal D, Marlow N, Derrick G, et al. The EPICure study: Maximal exercise and physical activity in school children born extremely preterm. Thorax. 2010;65:165-172. DOI: 10.1136/thx.2008.107474
  70. 70. Tikanmäki M, Tammelin T, Sipola-Leppänen M, Kaseva N, Matinolli HM, Miettola S, et al. Physical fitness in young adults born preterm. Pediatrics. 2016;137(1):e20151289. DOI: 10.1542/peds.2015-1289
  71. 71. Lowe J, Cousins M, Kotecha SJ, Kotecha S. Physical activity outcomes following preterm birth. Paediatric Respiratory Reviews. 2017;22:76-82. DOI: 10.1016/j.prrv.2016.08.012
  72. 72. McKay L, Goss KN, Haraldsdottir K, Beshish AG, Barton GP, Palta M, et al. Decreased ventricular size and mass mediate the reduced exercise capacity in adolescents and adults born premature. Early Human Development. 2021;160:105426. DOI: 10.1016/j.earlhumdev.2021.105426
  73. 73. Haraldsdottir K, Watson AM, Beshish AG, Pegelow DF, Palta M, Tetri LH, et al. Heart rate recovery after maximal exercise is impaired in healthy young adults born preterm. European Journal of Applied Physiology. 2019;119:857-866. DOI: 10.1007/s00421-019-04075-z
  74. 74. Rhodes J, Ubeda Tikkanen A, Jenkins KJ. Exercise testing and training in children with congenital heart disease. Circulation. 2010;122:1957-1967. DOI: 10.1161/CIRCULATIONAHA.110.958025
  75. 75. Hansen K, Tierney S. Every child with congenital heart disease should be exercising. Current Opinion in Cardiology. 2022;37:91-98. DOI: 10.1097/HCO.0000000000000931
  76. 76. Moalla W, Gauthier R, Maingourd Y, Ahmaidi S. Six-minute walking test to assess exercise tolerance and cardiorespiratory responses during training program in children with congenital heart disease. International Journal of Sports Medicine. 2005;26:756-762. DOI: 10.1055/s-2004-830558
  77. 77. Tran D, Maiorana A, Ayer J, Lubans DR, Davis GM, Celermajer DS, et al. Recommendations for exercise in adolescents and adults with congenital heart disease. Progress in Cardiovascular Diseases. 2020;63:350-366. DOI: 10.1016/j.pcad.2020.03.002
  78. 78. Thaulow E, Fredriksen PM. Exercise and training in adults with congenital heart disease. International Journal of Cardiology. 2004;97(Suppl. 1):35-38. DOI: 10.1016/j.ijcard.2004.08.007
  79. 79. Dulfer K, Duppen N, Kuipers IM, Schokking M, van Domburg RT, Verhulst FC, et al. Aerobic exercise influences quality of life of children and youngsters with congenital heart disease: A randomized controlled trial. The Journal of Adolescent Health. 2014;55:65-72. DOI: 10.1016/j.jadohealth.2013.12.010
  80. 80. Mota J, Vale S. Associations between sleep quality with cardiorespiratory fitness and BMI among adolescent girls. American Journal of Human Biology. 2010;22:473-475. DOI: 10.1002/ajhb.21019
  81. 81. Chen W, Gu X, Chen J, Wang X. Association of cardiorespiratory fitness and cognitive function with psychological well-being in school-aged children. International Journal of Environmental Research and Public Health. 2022;19:1434. DOI: 10.3390/ijerph19031434
  82. 82. Ruggero CJ, Petrie T, Sheinbein S, Greenleaf C, Martin S. Cardiorespiratory fitness may help in protecting against depression among middle school adolescents. The Journal of Adolescent Health. 2015;57:60-65. DOI: 10.1016/j.jadohealth.2015.03.016
  83. 83. Olive LS, Telford RM, Byrne DG, Abhayaratna WP, Telford RD. Psychological distress leads to reduced physical activity and fitness in children: The Australian longitudinal LOOK study. Journal of Behavioral Medicine. 2016;39:587-598. DOI: 10.1007/s10865-016-9723-0
  84. 84. Peralta M, Henriques-Neto D, Gouveia ÉR, Sardinha LB, Marques A. Promoting health-related cardiorespiratory fitness in physical education: A systematic review. PLoS One. 2020;15:e0237019. DOI: 10.1371/journal.pone.0237019
  85. 85. Calcaterra V, Larizza D, Codrons E, De Silvestri A, Brambilla P, Abela S, et al. Improved metabolic and cardiorespiratory fitness during a recreational training program in obese children. Journal of Pediatric Endocrinology & Metabolism. 2013;26:271-276. DOI: 10.1515/jpem-2012-0157
  86. 86. Labayen Goñi I, Arenaza L, Medrano M, García N, Cadenas-Sanchez C, Ortega FB. Associations between the adherence to the Mediterranean diet and cardiorespiratory fitness with total and central obesity in preschool children: The PREFIT project. European Journal of Nutrition. 2018;57:2975-2983. DOI: 10.1007/s00394-017-1571-3
  87. 87. Tambalis KD, Panagiotakos DB, Psarra G, Sidossis LS. Association of cardiorespiratory fitness levels with dietary habits and lifestyle factors in schoolchildren. Applied Physiology, Nutrition, and Metabolism. 2019;44:539-545. DOI: 10.1139/apnm-2018-0407
  88. 88. Parekh N, Henriksson P, Delisle Nyström C, Silfvernagel K, Ruiz JR, Ortega FB, et al. Associations of parental self-efficacy with diet, physical activity, body composition, and cardiorespiratory fitness in Swedish preschoolers: Results from the MINISTOP Trial. Health Education & Behavior. 2018;45:238-246. DOI: 10.1177/1090198117714019
  89. 89. Vafa M, Heshmati J, Sadeghi H, Shidfar F, Namazi N, Baradaran H, et al. Is exclusive breastfeeding and its duration related to cardiorespiratory fitness in childhood? The Journal of Maternal-Fetal & Neonatal Medicine. 2016;29:461-465. DOI: 10.3109/14767058.2015.1004052
  90. 90. Christodoulos AD, Douda HT, Tokmakidis SP. Cardiorespiratory fitness, metabolic risk, and inflammation in children. International Journal of Pediatrics. 2012;2012:270515. DOI: 10.1155/2012/270515

Written By

Mirjam Močnik and Nataša Marčun Varda

Submitted: March 20th, 2022 Reviewed: March 28th, 2022 Published: April 26th, 2022