Letter to the editor concerning the article “Effects of acoustic feedback training in elite-standard Para-Rowing” by Schaffert and Mattes (2015)

In a case study, Schaffert and Mattes reported the application of acoustic feedback (sonification) to optimise the time course of boat acceleration. The authors attributed an increased boat speed in the feedback condition to an optimised boat acceleration (mainly during the recovery phase). However, in rowing it is biomechanically impossible to increase the boat speed significantly by reducing the fluctuations in boat acceleration during the rowing cycle. To assess such a, potentially small, optimising effect experimentally, the confounding variables must be controlled very accurately (that is especially the propulsive forces must be kept constant between experimental conditions or the differences in propulsive forces between conditions must be much smaller than the effects on boat speed resulting from an optimised movement pattern). However, this was not controlled adequately by the authors. Instead, the presented boat acceleration data show that the increased boat speed under acoustic feedback was due to increased propulsive forces.     

Letter to the editor concerning the article “Bar velocities capable of optimising the muscle power in strength-power exercises” by Loturco,Pereira, Abad,Tabares, Moraes,Kobal, Kitamura & Nakamura (2017)

Loturco and co-workers (2017) recently published data in the Journal of Sports Sciences to present the optimum loading magnitudes regarding the maximization of the “mean propulsive power” of the leg and arm muscles. Among the most important findings were that (1) the recorded power in the squat and squat jump exercises was markedly low, (2) the optimum external load that maximized the power in the same exercises was close to 100% of body weight, while (3) the ballistic bench press throw revealed smaller power than the regular bench press typically performed with relatively low level of muscle activation towards the end of the propulsive lifting phase. The findings are either counter-intuitive, or contradict the literature findings, or both, and we believe that they originate from apparent methodological flaws. The first one is neglecting the force acting against the body segments moved together with the external load that is particularly high in squat exercises. The second one is an erroneous calculation of the propulsive phase that included a part of the bar’s flight time. Both of these methodological flaws are frequent in the literature and could be associated with the improper use and calculation of variables when utilizing linear position transducers.     

Letter to the editor concerning the article “Relationship between school rhythm and physical activity in adolescents: the HELENA study” by Vanhelst et al. (2017)

Recently Vanhelst et al. published a study on the relationship between school rhythm and physical activity patterns in European adolescents in the Journal of Sports Sciences. With this Letter to the Editor we would like to comment on the practical implementation and further perspectives of the study.     

Authors’ response to letter to the editor: “Bar velocities capable of optimising the muscle power in strength-power exercises” by Loturco,Pereira, Abad,Tabares, Moraes,Kobal, Kitamura & Nakamura (2017)

Our study in the Journal of Sports Sciences was originally designed to test whether the bar-velocity is a precise indicator of the power training intensity (i.e., optimum loads) in different exercises commonly included in athletes’ training programs. Furthermore, we presented secondary findings, related to the actual results obtained in our assessments. As a cross-sectional study with clear objectives, we focused on discussing issues and applications pertaining to neuromuscular training interventions, such as: (1) describing the advantages of using bar-velocities to control the power training intensity, (2) defining a range of loads capable of maximizing the power production in certain ballistic and traditional exercises, and (3) revealing the differences between these exercises and the respective implications for training. Fundamentally, we did not produce a mechanistic investigation and were very accurate and consistent in reporting our data, collected under rigorous and well-established experimental conditions. Here we provide our point-by-point comments to the concerns raised in the “Letter to the Editor”, along with some theoretical explanations about the secondary findings reported by the authors of the Letter. To better understand the nature and purposes of our experiment, we also present a series of practical examples and review previous investigations involving the “bar-power” approach.