ORIGINAL ARTICLE Muscle mechanical characteristics in fatigue and recovery from a marathon race in highly trained runners Kim Petersen Æ Claus Bugge Hansen Æ Per Aagaard Æ Klavs Madsen Accepted: 2 June 2007 / Published online: 28 July 2007 Ó Springer-Verlag 2007 Abstract The aim of the present study was to examine muscle mechanical characteristics before and after a mar- athon race. Eight elite runners underwent a pre-test 1 week before the marathon and post-tests 30 min, two and five- day-post-marathon. Actual marathon race performance was 2:34:40 ± 0:04:13. Energy expenditure at marathon pace (EE Mpace ) was elevated 4% post-marathon (pre: 4,465 ± 91 vs. post 4,638 ± 91 J kg bodyweight –1 km –1 , P < 0.05), but was lowered by 6 and 9.5% two- and five-day-post- marathon compared to EE Mpace pre-marathon. Counter- movement jump (CMJ) power decreased 13% post-mara- thon (pre: 21.5 ± 0.9 vs. post: 18.9 ± 1.2 W kg –1 ; P < 0.05) and remained depressed two- (18%) and five-day (12%) post-marathon. CMJ force was unaltered across all four tests occasions. Knee extensor and plantar flexor maximal voluntary contraction (MVC) decreased from 176.6 ± 9.5 to 136.7 ± 16.8 Nm and 144.9 ± 8.7 to 119.2 ± 15.1 Nm post-marathon corresponding to 22 and 17%, respectively (P < 0.05). No significant changes were detected in evoked contractile parameters, except a 25% increase in force at 5 Hz, and low frequency fatigue was not observed. In conclusion, leg muscle power decreased acutely post-marathon race and recovered very slowly. The post-marathon increase in EE Mpace might be attributed to a reduction in stretch shortening cycle efficiency. Finally, since MVC was reduced after the marathon race without any marked changes in evoked muscle contractile proper- ties, the strength fatigue experienced by the subjects in this study seems to be related to central rather than peripheral mechanisms. Keywords Marathon performance  Neuromuscular fatigue  Running economy  Endurance athletes Introduction For many years exercise physiologists have studied the potential limiting factors for endurance performance in untrained and trained individuals. Many studies have fo- cused on metabolic factors, primarily muscle and liver glycogen depletion, as a cause of fatigue in prolonged exercise such as the marathon event. Low glycogen levels in muscle have been found in fatigued subjects (Tzintzas et al. 1996; Sherman et al. 1983; Callow et al. 1986), and performance was markedly impaired when subjects were given a low-carbohydrate diet before exercise (Bergstrøm et al. 1967). However no studies have been able to establish a direct link between glycogen depletion and fatigue, and substantial quantities of glycogen remain in the muscles at exhaustion in highly trained athletes (Madsen et al. 1990, 1993; Noakes et al. 1988; Noakes 2001). Training status might play an important role since endurance trained ath- letes oxidize less carbohydrate and have substatial higher glycogen stores compared to sedentary subjects for the same absolute work due to a lower rate of glycogenolysis during exercise (Gollnick and Saltin 1988; Coggan and Williams 1995). Therefore other factors seem to play a governing role in fatigue during prolonged exercise in well-trained athletes. More recent research on prolonged exercise has addressed the role of muscle and neuromuscular fatigue in relation to endurance performance. Neuromuscular fatigue can be K. Petersen  C. B. Hansen  P. Aagaard  K. Madsen (&) Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark e-mail: klamadsen@health.sdu.dk 123 Eur J Appl Physiol (2007) 101:385–396 DOI 10.1007/s00421-007-0504-x