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Abstract: Mitochondrial background has been demonstrated to influence maximal oxygen uptake (VO2max, in mLkg−1 min−1), but this genetic influence can be compensated for by regular exercise. A positive correlation among electron transport chain (ETC) coupling, ATP and reactive oxygen species (ROS) production has been established, and mitochondrial variants have been reported to show differences in their ETC performance. In this study, we examined in detail the VO2max differences found among mitochondrial haplogroups. We recruited 81 healthy male Spanish Caucasian individuals and determined their mitochondrial haplogroup. Their VO2max was determined using incremental cycling exercise (ICE). VO2max was lower in J than in non-J haplogroup individuals (P =0.04). The H haplogroup was responsible for this difference (VO2max; J vs. H; P =0.008) and this group also had significantly higher mitochondrial oxidative damage (mtOD) than the J haplogroup (P =0.04). In agreement with these results, VO2max and mtOD were positively correlated (P =0.01). Given that ROS production is the major contributor to mtOD and consumes four times more oxygen per electron than the ETC, our results strongly suggest that ROS production is responsible for the higher VO2max found in the H variant. These findings not only contribute to a better understanding of the mechanisms underneath VO2max, but also help to explain some reported associations between mitochondrial haplogroups and mtOD with longevity, sperm motility, premature aging and susceptibility to different pathologies. [Copyright &y& Elsevier]

Abstract: It has been clearly established that mitochondrial variants, among other potential factors, influence on VO2max. With this study we sought to determine whether this genetic predisposition could be modified by steady exercise. Mitochondrial genetic variants were determined in 70 healthy controls (CON) and in 77 athletes who trained regularly (50 cyclists, aerobic training (AER), and 27 runners of 400m, anaerobic training (NoAER)). All of them were male Spanish Caucasian individuals. A maximum graded exercise test (GXT) in cycle-ergometer was performed to determine VO2max (mLkg−1 min−1). Our results confirmed that, in CON, VO2max (P =0.007) was higher in Non-J than J individuals. Furthermore, we found that AER and NoAER showed, as it could be expected, higher VO2max than CON, but not differences between mitochondrial variants have been found. According with these findings, the influence of mitochondrial DNA (mtDNA) variants on VO2max has been confirmed, and a new conclusion has arisen: the steady exercise is able to remove this influence. The interest of these promising findings in muscular performance should be further explored, in particular, the understanding of potential applications in sport training and in muscle pathological syndromes. [Copyright &y& Elsevier]