News & Views from the Editor-in-Chief - L. Bruce Gladden
I am excited to once again call out three articles in this month's issue of MSSE® (July 2018). In the first highlight, Elsangedy et al. evaluated the feasibility and reliability of self-regulated resistance training using the Feeling Scale (FS). They found the FS to be a valid, useful, and reliable tool to self-regulate exercise intensity during resistance training. There was an inverse linear relationship between the feeling of pleasure/displeasure and exercise intensity during resistance training over a wide range of FS descriptors (+5 to -1). Accordingly, using the FS for resistance training prescription will correspond well with the ACSM intensity zones. Another advantage of using the FS as a complementary method to prescribe exercise intensity is that it may facilitate the experience of a positive affective response from the exercise, perhaps providing extra motivation to maintain exercise training.
Flat feet have been commonly implicated in numerous clinical disorders, including posterior tibial tendon dysfunction (PTTD). This motivated Maharaj et al. to explore the immediate influence of custom-made foot orthoses in asymptomatic individuals with a flat foot. At comfortable walking speeds, both footwear alone and footwear with orthotics reduced loads and energy absorbed by structures around the subtalar joint (STJ) when the foot impacted with the ground. This subsequently required less activation of the tibialis posterior (TP) muscle, the main structure that stretches and absorbs energy across the STJ. Therefore, footwear acts to reduce stresses and strains on the TP muscle and tendon during walking, and in the context of this study, there appeared to be no added benefits of orthotics. This result questions the immediate role of orthotics in treating disorders like PTTD, although orthotics may have longer term benefits that were not explored.
Myonuclear domain theory postulates that myonuclei are added to muscle fibers when increases in fiber cross-sectional area (i.e., hypertrophy) are greater than about 25%. Many but not all studies have supported this theory. One of the causes of the discrepancies is the low statistical power. To mitigate this problem, Conceição et al. performed a meta-analysis that included 903 participants. In contrast to current opinion, the meta-analysis showed that myonuclei addition may occur with increases in muscle fiber cross-sectional area of as little as ~10%, although a more robust myonuclei addition is observed when muscle fiber hypertrophy exceeds ~22%. Although endurance training induces muscle fiber hypertrophy and increases myonuclear content, it does so to a lesser extent than resistance training. Age, sex, and fiber type did not appear to differentially affect myonuclear addition.
L. Bruce Gladden
School of Kinesiology