To assess the effects of regular physical activity on muscle functional characteristics of carriers of sickle cell trait (SCT), 39 untrained (U) and trained (T) HbAA (CON) and SCT subjects (U-CON, n = 12; U-SCT, n = 8; T-CON, n = 10; and T-SCT, n = 9) performed a graded exercise and a time to exhaustion (Tex) test, and were subjected to a muscle biopsy. Maximal power, total work performed during Tex, citrate synthase and cytochrome c oxidase (COx) activities, respiratory chain complexes I and IV content and capillary density (CD), diameter (COD) and surface area (CSA) were up-regulated by the same proportion in T-CON and T-SCT compared to their untrained counterparts. These proportionally similar differences imply that the observed discrepancies between U-SCT and U-CON remained in the trained subjects. Specifically, both CD and COx remained and tended to remain lower, and both COD and CSA remained and tended to remain higher in T-SCT than in T-CON. Besides, carriers of SCT displayed specific adaptations with regular physical activity: creatine kinase activity, complexes II, III and V content, type I fiber surface area and capillary tortuosity were lower or unchanged in T-SCT than in U-SCT. In summary, our results show that i) carriers of SCT adapted almost similarly to CON to regular physical activity for most of the studied muscle characteristics, ii) oxidative potential remains altered in physically active carriers of SCT compared to HbAA counterparts, and iii) the specific remodeling of muscle microvascular network persists in the trained state.
- habitual physical activity
- enzyme activity
- muscle fiber types distribution
- microvascular network
- fiber surface area
- Copyright © 2012, Journal of Applied Physiology