News & Views from the Editor-in-Chief - L. Bruce Gladden
As usual, I chose three stand-out papers this month. First, Warden and colleagues used state-of-the-art high-resolution peripheral quantitative computed tomography (HR-pQCT) to study tennis players in a within-subject controlled model to demonstrate the benefits of physical activity on bone microarchitecture and estimated strength. They found more trabeculae that were thicker and more connected in the distal radius in the racquet arms of tennis players than in their contralateral non-racquet arms. These attributes contributed to an 18.7% greater estimated strength to loading in a fall-related direction. Interestingly, the tibia in the leg opposite the racquet arm also had enhanced properties. These findings extend previous data to demonstrate the importance of physical activity on novel measures of bone microarchitecture and strength and reveal that tennis players exhibit crossed symmetry.
Second, prenatal exercise is associated with a 40% reduction in the development of high blood pressure during pregnancy, yet the underlying reasons for this are unknown. In this context, Skow and colleagues performed a randomized controlled trial to determine the effects of an aerobic exercise training program between 20 and 34 weeks gestation on the sympathetic nervous system's control of blood pressure. They found that walking for 40 minutes 3-4 times per week resulted in a lesser increase in muscle sympathetic nerve activity with gestation. This may provide one mechanism by which aerobic exercise reduces the odds of developing gestational hypertension and preeclampsia and further promotes the notion of physical activity during pregnancy.
Finally, Kugler et al. compared the effects of electrical pulse stimulation (EPS) on the mitochondrial network structure and regulatory proteins in cultured myotubes from lean versus severely obese humans. Their purpose was to use a reductionist approach to investigate mitochondrial adaptations in response to “exercise" training in healthy versus insulin-resistant individuals. Their results provided evidence that 24 hours of EPS, a model of muscle contraction, induced a more interconnected mitochondrial network in primary myotubes from both lean and severely obese humans. However, there were also distinct adaptations in myotubes from lean and severely obese humans. Specifically, EPS promoted a profusion environment by increasing mitochondrial fusion protein Mfn2 in myotubes from lean humans, whereas EPS reduced mitochondrial fission protein Drp1 Ser616 phosphorylation in severely obese humans. Further integrative studies are needed to extend these results to intact humans and to clarify their precise relevance to insulin resistance.
L. Bruce Gladden
School of Kinesiology