title: Postexercise heart rate recovery in children: relationship with power output, blood pH, and lactate.
abstract: The aim of the present study was to determine whether differences in age-related heart rate recovery (HRR) kinetics were associated with differences in power output, blood lactate concentration ([La]b), and acidosis among children, adolescents, and adults. Ten prepubertal boys (aged 9.6 +/- 0.7 years), 6 pubertal boys (aged 15.2 +/- 0.8 years), and 7 men (aged 20.4 +/- 1.0 years) performed 10 repeated 10-s all-out cycling sprints, interspersed with 5-min passive recovery intervals. Mean power output (MPO) was measured during each sprint, and HRR, [La]b, and acidosis (pHb) were determined immediately after each sprint. Children displayed a shorter time constant of the primary component of HRR than adolescents and adults (17.5 +/- 4.1 vs. 38.0 +/- 5.3 and 36.9 +/- 4.9 s, p < 0.001 for both), but no difference was observed between adolescents and adults (p = 1.00). MPO, [La]b, and pHb were also lower in children compared with the other 2 groups (p < 0.001 for both). When data were pooled, HRR was significantly correlated with MPO (r = 0.48, p < 0.001), [La]b (r = 0.58, p < 0.001), and pHb (r = -0.60, p < 0.001). Covarying for MPO, [La]b, or pHb abolished the between-group differences in HRR (p = 0.42, p = 0.19, and p = 0.16, respectively). Anaerobic glycolytic contribution and power output explained a significant portion of the HRR variance following high-intensity intermittent exercise. The faster HRR kinetic observed in children appears to be related, at least in part, to their lower work rate and inherent lack of anaerobic metabolic capacity.
authors.affiliation: Research Laboratory, Exercise physiology and rehabilitation, Faculty of Sport Sciences, University of Picardie Jules Verne, Amiens, France. martin.buchheit@u-picardie.fr
authors.forename: Martin
authors.initials: M
authors.lastname: Buchheit
authors.forename: Pascale
authors.initials: P
authors.lastname: Duché
authors.forename: Paul B
authors.initials: PB
authors.lastname: Laursen
authors.forename: Sébastien
authors.initials: S
authors.lastname: Ratel
mesh_terms: D000140:Acidosis, Lactic / Q000097:blood / Q000503:physiopathology*; D000293:Adolescent; D000367:Age Factors; D000375:Aging; D001642:Bicycling; D015415:Biomarkers / Q000097:blood; D002648:Child; D015444:Exercise; D006019:Glycolysis; D006339:Heart Rate; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism / Q000503:physiopathology*; D000091402:Prohibitins; D020127:Recovery of Function; D055815:Young Adult
chemical_list: D015415:Biomarkers; C000717328:PHB protein, human; D000091402:Prohibitins; D019344:Lactic Acid