Abstract 
         
         In this paper, we examine the association between polymorphisms of the angiotensin-converting
            enzyme (ACE) and muscle-specific creatine kinase (CKMM) genes, and the actual performance
            status observed in professional cyclists capable of completing a classic tour stage
            race such as the Giro d'Italia, Tour de France, or Vuelta a España. To accomplish
            this, we compared the frequencies of the ACE and CKMM genotypes/alleles in 50 top-level
            Spanish professional cyclists that have completed at least one of these events to
            119 sedentary controls, and 27 elite (Olympic-class) Spanish runners. The genetic
            polymorphism at the CK-MM locus was detected with the NcoI  restriction endonuclease. The results of our study showed that the proportion of
            the DD genotype was higher in cyclists (50.0 %) than in the other two groups (p <
            0.05), the proportion of the ID genotype was higher in controls (46.2 %) than in the
            other two groups (p < 0.05), and the proportion of the II genotype was higher in runners
            (40.7 %) than in the other two groups (p < 0.05). The proportion of the D allele was
            higher in both cyclists (65.0 %) and controls (57.6 %) than in runners (46.3 %) (p
            < 0.001), whereas the proportion of the I allele was higher in runners than in the
            other two groups (p < 0.001). No statistical differences were found for CKK-MM-NcoI.  We conclude that in top-level professional cyclists capable of completing a classic
            3-wk tour race, the frequency distribution of the D allele and the DD genotype seems
            to be higher than in other endurance athletes such as elite runners (in whom the I
            allele is especially frequent).
         
         
         
            
Key words 
         
         
            Genotype - allele - sports - endurance
          
       
    
   
      
         References 
         
         
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         alejandro.lucia@mrfs.cisa.uem.es