I have selected three studies in the May 2016 MSSE® for special attention. In the first study, Layec et al. simultaneously assessed ATP synthesis with 31P-Magnetic Resonance Spectroscopy and O2 uptake with pulmonary gas exchange measurements to examine in vivo potential differences in mitochondrial efficiency and ATP cost of contraction during exercise in two groups of adults differing in aerobic power (O2max). Despite a greater mitochondrial capacity for ATP synthesis in the quadriceps, endurance-trained subjects exhibited a similar mitochondrial efficiency and ATP cost of contraction during knee-extension exercise in comparison to recreationally active individuals. Together, these cross-sectional findings suggest that endurance training, which is an effective way to improve O2max and muscle phosphorylation capacity, does not appear to influence the main physiological determinants of muscle efficiency; i.e., mitochondrial and contractile efficiency.
In the second highlighted study, Périard and Racinais examined performance and pacing during prolonged time trial exercise in temperate, hyperthermic, and hypoxic conditions to create models with a stable, progressively decreasing, and acutely decreased O2max, respectively. Despite an acutely reduced O2max and average power output during the hypoxic trial, pacing was similar to that of temperate conditions, as was the relative intensity (%O2max) sustained. In contrast, the progressive decrease in power output in the hyperthermic condition resulted in a more pronounced positive pacing pattern, with %O2max decreasing throughout the time trial. These data indicate that performance and pacing during prolonged self-paced exercise are associated with the maintenance of relative exercise intensity within a narrow range, or optimal performance intensity, in conjunction with both acute and progressive reductions in maximal aerobic power.
Finally, Sardinha et al. examined the prospective associations between cardiovascular fitness (CRF) and academic achievement in a sample of 1,286 Portuguese children age 11-14 years. CRF was assessed by the PACER test from Fitnessgram. Children were classified into four groups; fit-fit, unfit-fit, fit-unfit, and unfit-unfit according to PACER test results at baseline and follow up. Being persistently fit (fit-fit), increased the odds of having high levels of academic achievement in Portuguese (OR=3.49, p<0.001), and Foreign Language (OR=2.41, p<0.01), at follow-up. Children who improved their CRF and became fit (unfit-fit) also had higher odds of achieving better marks than those who were persistently unfit-unfit. Overall these results suggested that being consistently highly fit and improving fitness were both prospectively associated with better academic achievement in both native and foreign language.