News & Views from the Editor-in-Chief - L. Bruce Gladden
I'm calling special attention to three papers in this month's journal. First, Weatherwax et al. studied the effect of steady-state aerobic exercise intensity prescription on overall training responsiveness according to changes in cardiorespiratory fitness (CRF) in previously sedentary adults. Their participants completed exercise training 3 d·wk−1 for 12 wk with exercise intensity prescribed based on either heart rate reserve (standardized group) or ventilatory threshold (individualized group). In the individualized group, the CRF training responsiveness was 100% versus only 60% in the standardized group. They concluded that a threshold model for exercise intensity prescription had a greater effect on the incidence of CRF training responsiveness when compared to a standardized approach. The use of ventilatory threshold as an intensity marker accounts for individual metabolic characteristics and should be considered as a viable and perhaps superior method for prescribing exercise intensity.
Next, Betts et al. addressed an important gap in current understanding by reporting the energy cost of sitting and standing naturally (i.e., without other activities except fidgeting). Previous estimates of this difference come from laboratory-based experiments in which participants remain completely motionless or, at the other extreme, from field-based observations involving perambulation when not seated. Therefore, the 12% increment reported by Betts et al. reveals the fundamental contrast when substituting standing for sitting, which is less than half of the earlier estimates that included other activities. This equates to an additional energy expenditure of a bit over 9 kcal for every hour of standing, which the authors note was almost entirely fueled by the oxidation of lipid (1.0 ± 0.4 g·h−1) rather than carbohydrate (0.002 ± 1.0 g·h−1).
Finally, Bonnaerens et al. investigated grounded running, which is slow running that is characterized by the absence of a flight phase, resulting in a flatter running pattern. In their research, young athletic subjects ran at 7.5 km·h−1, changing their natural running style (i.e., running with a flight phase) to a grounded running pattern upon the simple instruction "run without a flight phase." When adopting the grounded running pattern, several parameters that depict musculoskeletal loading decreased by up to 35%, while the activity remained at a moderate-to-vigorous level. Accordingly, the lower loading on the musculoskeletal system during grounded running could offer a solution for people who have a lower loading capacity, since it has the potential to postpone muscular fatigue and even reduce the risk of running related injuries.
L. Bruce Gladden
School of Kinesiology