Abstract
IntroductionThe insertion/deletion (I/D) polymorphism in the gene for the major regulator of vascular tone, angiotensin-converting enzyme-insertion/deletion (ACE-I/D) affects muscle capillarization and mitochondrial biogenesis with endurance training. We tested whether changes of leg muscle oxygen saturation (SmO2) during exhaustive exercise and recovery would depend on the aerobic fitness status and the ACE I/D polymorphism.MethodsIn total, 34 healthy subjects (age: 31.8 ± 10.2 years, 17 male, 17 female) performed an incremental exercise test to exhaustion. SmO2 in musculus vastus lateralis (VAS) and musculus gastrocnemius (GAS) was recorded with near-IR spectroscopy. Effects of the aerobic fitness status (based on a VO2peak cutoff value of 50 ml O2 min−1 kg−1) and the ACE-I/D genotype (detected by PCR) on kinetic parameters of muscle deoxygenation and reoxygenation were assessed with univariate ANOVA.ResultsDeoxygenation with exercise was comparable in VAS and GAS (p = 0.321). In both leg muscles, deoxygenation and reoxygenation were 1.5-fold higher in the fit than the unfit volunteers. Differences in muscle deoxygenation, but not VO2peak, were associated with gender-independent (p > 0.58) interaction effects between aerobic fitness × ACE-I/D genotype; being reflected in a 2-fold accelerated deoxygenation of VAS for aerobically fit than unfit ACE-II genotypes and a 2-fold higher deoxygenation of GAS for fit ACE-II genotypes than fit D-allele carriers.DiscussionAerobically fit subjects demonstrated increased rates of leg muscle deoxygenation and reoxygenation. Together with the higher muscle deoxygenation in aerobically fit ACE-II genotypes, this suggests that an ACE-I/D genotype-based personalization of training protocols might serve to best improve aerobic performance.
Highlights
The insertion/deletion (I/D) polymorphism in the gene for the major regulator of vascular tone, angiotensin-converting enzyme-insertion/deletion (ACE-I/D) affects muscle capillarization and mitochondrial biogenesis with endurance training
The ACE-I/D genotype was not associated with differences in VO2peak or Peak Power Output (PPO) independent of whether assessed as single effect (p = 1.00, p = 0.26) or interaction effect with the aerobic fitness state (p = 0.85, p = 0.44; Table 1)
The aim of this study was to investigate whether a nearIR spectroscopy (NIRS)-based measure of the balance between supply and use of oxygen during exhaustive pedaling exercise is associated with the ACE-I/D genotype and stands in dependence of the fitness state (Casey and Joyner, 2015; Ross et al, 2019)
Summary
The insertion/deletion (I/D) polymorphism in the gene for the major regulator of vascular tone, angiotensin-converting enzyme-insertion/deletion (ACE-I/D) affects muscle capillarization and mitochondrial biogenesis with endurance training. We tested whether changes of leg muscle oxygen saturation (SmO2) during exhaustive exercise and recovery would depend on the aerobic fitness status and the ACE I/D polymorphism. The implicated enhancement of mitochondrial respiration in contracting skeletal muscle can be readily, and indirectly, detected based on an increased signal for deoxygenated myoglobin/hemoglobin as measurable with nearIR spectroscopy (NIRS) (Nioka et al, 1998; Richardson et al, 2001; Perrey and Ferrari, 2018). The thereby observable decreases in muscle oxygen saturation (SmO2) are graded to the duration and intensity of exercise (Nioka et al, 1998; Chuang et al, 2002) and seem to be faster at the local, compared to the systemic (i.e., cardiopulmonary) level (Nioka et al, 1998; Grassi and Quaresima, 2016). The changes in muscle oxygen saturation during intense prolonged exercise are dependent on the endurance capacity, respectively, aerobic fitness (Hoppeler et al, 1985). An improved regain of oxygen saturation (reoxygenation) with the offset of exercise (Jones et al, 2017; Perrey and Ferrari, 2018)
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