News & Views from the Editor-in-Chief - L. Bruce Gladden
As usual, I am highlighting three papers in this month's journal. First, based on recent results in normal-weight subjects, Zuccarelli and colleagues investigated how obese patients might respond in maintaining a fixed heart rate during submaximal exercise. During a 15-min exercise set at a fixed heart rate (HR), slightly above that corresponding to the gas exchange threshold, obese patients had to decrease their work rate by about 20% resulting in a 10% decrease in oxygen uptake. Thus, in obese patients exercise prescription at a fixed HR is not associated with a specific work rate or exercise domain. Also, exercise evaluation is affected, for example in terms of the quantification of the metabolic cost. After a 3-wk multidisciplinary (including exercise training) body mass reduction intervention, the work rate decrease at the fixed HR was significantly less pronounced. This work rate decrease can be considered a biomarker of impaired exercise tolerance.
Second, Gliemann et al. evaluated the association between the level of 20 years of habitual physical activity (from inactive to moderate to very active lifestyle), on skeletal muscle exercise hemodynamics and oxygen extraction in postmenopausal women. While there was no difference between the moderately active and sedentary women, these authors found that very active women presented with more optimal skeletal muscle hemodynamics and a greater potential for oxygen extraction. Some of the underlying factors appeared to be greater muscle capillarization, greater muscle mitochondrial complex content, and greater muscle VEGF content in the very active group compared to the moderately active and sedentary women. These findings suggest that a high degree of regular physical activity throughout life is required for improved oxygen extraction in aged women.
Finally, Viellehner and Potthast investigated the effect of vibration on short-term neuromuscular performance in cycling. For this purpose, the vibration stimulus acting on the musculoskeletal system, the neuromuscular response and the resulting metabolic demands were analyzed. Their key findings were that vibration is transmitted to the entire musculoskeletal system. Since the main propulsive muscles such as the vastus lateralis or rectus femoris did not systematically increase activation during vibration, the effect on propulsion was considered to be limited. High vibration loads and increased muscular activation of the hand–arm system suggest that the vibration related additional oxygen uptake of 2.7% is also the result of non-propulsive, stabilizing tasks on the bike. These results suggest potential areas of focus for training interventions and equipment development.
L. Bruce Gladden
School of Kinesiology