title: Effects of marathon running on running economy and kinematics.
abstract: The present study was designed to investigate interactions between running economy and mechanics before, during, and after an individually run marathon. Seven experienced triathletes performed a 5-min submaximal running test on a treadmill at an individual constant marathon speed. Heart rate was monitored and the expired respiratory gas was analyzed. Blood samples were drawn to analyze serum creatine kinase activity (S-CK), skeletal troponin I (sTnI), and blood lactate (B-La). A video analysis was performed (200 frames x s(-1)) to investigate running mechanics. A kinematic arm was used to determine the external work of each subject. The results of the present study demonstrate that after the marathon, a standardized 5-min submaximal running test resulted in an increase in oxygen consumption, ventilation, and heart rate (P < 0.05), with a simultaneous decrease in the oxygen difference (%) between inspired and expired air, and respiratory exchange ratio (P < 0.05). B-La did not change during the marathon, while sTnI and S-CK values increased (P < 0.05), peaking 2 h and 2 days after the marathon, respectively. With regard to the running kinematics, a minor increase in stride frequency and a similar decrease in stride length were observed (P < 0.01). These results demonstrate clearly that weakened running economy cannot be explained by changes in running mechanics. Therefore, it is suggested that the increased physiological loading is due to several mechanisms: increased utilization of fat as an energy substrate, increased demands of body temperature regulation, and possible muscle damage.
authors.affiliation: Department of Biology of Physical Activity, University of Jyväskylä, Finland. heikki@maila.jyu.fi
authors.forename: H
authors.initials: H
authors.lastname: Kyröläinen
authors.forename: T
authors.initials: T
authors.lastname: Pullinen
authors.forename: R
authors.initials: R
authors.lastname: Candau
authors.forename: J
authors.initials: J
authors.lastname: Avela
authors.forename: P
authors.initials: P
authors.lastname: Huttunen
authors.forename: P V
authors.initials: PV
authors.lastname: Komi
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003402:Creatine Kinase / Q000097:blood; D004734:Energy Metabolism; D005260:Female; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption; D010953:Plasma Volume; D012420:Running / Q000502:physiology*; D019210:Troponin I / Q000097:blood
chemical_list: D019210:Troponin I; D019344:Lactic Acid; D003402:Creatine Kinase; D009638:Norepinephrine