Research letter High-intensity, high-volume exercise in addition to school exercise classes reduces endothelial progenitor cells, inflammation and catabolism in adolescent boys Magda Henriques 1,2 , Raquel Fernandes 1,2 , Ana Cristina Gonc¸alves 3 , Ilda Patrı ´cia Ribeiro 3 , Rui Santos 4 , Margarida Fardilha 1,2 , Rita Ferreira 5 and Fernando Ribeiro 2,6 Physical exercise seems to increase the number of cir- culating endothelial progenitor cells (EPCs) in healthy people and in patients with cardiovascular disease (CVD). 1 EPCs are circulating precursors of endothelial cells derived from the bone marrow and can enhance endothelial repair, neovascularization and endothelial function. 2 Daily school exercise classes for one year increased the number of EPCs in schoolchildren relative to the standard twice-a-week exercise classes. 3,4 High exercise levels seem to have advantages, but previous studies in swimmers have shown epithelial damage and increased inflammation of the airways as a result of intensive training combined with exposure to the by-products of chlorination. 5 Alterations in systemic immune par- ameters suggestive of suppressed immunity during and immediately after training sessions have also been reported, such as changes in the capacity of immune cells to produce inflammatory cytokines in response to an external stimulus. 6 The effects of the addition of high-intensity, high- volume exercise in addition to school exercise classes on the levels of circulating EPCs is poorly understood in adolescents. We aimed to assess the effect of high- intensity, high-volume swimming in adolescents, in addition to regular school exercise classes, on the levels of circulating EPCs and other inflammatory and catabolic parameters. Sixteen boys, eight elite swimmers from a swimming club and eight age-matched boys from a secondary school located in the same district, were invited to par- ticipate in the study. The inclusion criteria were: (a) age between 13 and 16 years; and (b) participation in 5 training sessions/week in the last year (swimmers’ group), or no regular exercise/sports practice other than school exercise classes (age-matched group), in the 12 months preceding the study. The exclusion cri- teria were: (a) contraindications to exercise; (b) cardiovascular, respiratory or metabolic disease; (c) musculoskeletal injuries compromising regular exercise participation; and (d) any medication. The ethics com- mittee approved the study (ref: 163/AD). Written informed consent was obtained from the parents/ guardians of the participants. Clinical history, exercise participation, height, weight and body composition (Seca mBCA 514, Birmingham, UK) were recorded. Fasting blood samples were col- lected by venipuncture of the antecubital vein into serum separator or EDTA-coated tubes at least 24h after the last training session. EPCs were measured by flow cytometry (FACS-Calibur flow cytometer, Becton Dickinson, San Jose, CA, USA) as described previ- ously. 7 In brief, whole blood samples were labelled with monoclonal antibodies against CD34 (APC, Miltenyi Biotec), CD309 (VEGFR-2/KDR; PE, Miltenyi Biotec) and CD45 (FITC, Miltenyi Biotec) according to the manufacturer’s instructions. After erythrocyte lysis, at least 250,000 CD45 þ events were acquired and a minimum of 100 CD34 þ cells were col- lected in each sample. The data were analysed using Paint-a-Gate software (Becton Dickinson) and the iden- tification of the EPCs was based on morphological 1 Department of Medical Sciences, University of Aveiro, Portugal 2 Institute of Biomedicine – iBiMED, University of Aveiro, Portugal 3 Cytogenetics and Genomics Laboratory, iCBR-CIMAGO – Center of Investigation on Environment Genetics and Oncobiology – Faculty of Medicine, University of Coimbra, Portugal 4 Clube dos Galitos, Portugal 5 QOPNA & LAQV, Department of Chemistry, University of Aveiro, Portugal 6 School of Health Sciences, University of Aveiro, Portugal Corresponding author: Fernando Ribeiro, School of Health Sciences, University of Aveiro – Building 30, Agras do Crasto – Campus Universita´rio de Santiago 3810- 193 Aveiro, Portugal. Email: fernando.ribeiro@ua.pt European Journal of Preventive Cardiology 2020, Vol. 27(19) 2255–2258 ! The European Society of Cardiology 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/2047487319884793 journals.sagepub.com/home/cpr Downloaded from https://academic.oup.com/eurjpc/article/27/19/2255/6125475 by guest on 07 April 2022