Int J Sports Med 2004; 25(4): 247-251
DOI: 10.1055/s-2004-819933
Physiology & Biochemistry

© Georg Thieme Verlag KG Stuttgart · New York

Sperm Characteristics of Endurance Trained Cyclists

Y. Gebreegziabher1 , E. Marcos1 , W. McKinon1 , G. Rogers1
  • 1School of Physiology, University of the Witwatersrand Medical School, 7 York Road, Parktown, South Africa
Further Information

Publication History

Accepted after revision: June 25, 2003

Publication Date:
26 May 2004 (online)


The purpose of this study was to investigate the influence of cycling on sperm characteristics. Twenty subjects volunteered for the study, comprising 10 long distance competitive cyclists (median 25.5 y) and 10 sedentary controls (median 24.5 y). A questionnaire was used to obtain a history of training, health, nutrition and life style. Semen analysis consisted of a detailed evaluation of sperm characteristics that included semen volume, sperm count, viability, motility and morphology. Compared to controls, the cyclists had a significantly lower proportion of spermatozoa with normal morphology (medians: 41.5 % versus 19.5 %; p < 0.01) and a significantly higher proportion of morphologically abnormal tapered forms (medians: 4.5 % versus 22.5 %; p < 0.01). No significant difference in semen volume and sperm motility, viability and count was observed between the two groups. We concluded that endurance cycling appears to be associated with a significant alteration in sperm morphology.


G. Rogers

School of Physiology · University of the Witwatersrand

Private Bag 3 · 2050 WITS · Johannesburg · South Africa

Email: [email protected]