Purpose: To describe the load–velocity relationship and the effects of increasing loads on spatiotemporal and derived kinetic variables of sprinting using weighted vests (WV) in soccer players and determining the load that maximizes power output. Methods: A total of 23 soccer players (age 20.8 [1.5] y) performed 10 maximal 30-m sprints wearing a WV with 5 different loads (0%, 10%, 20%, 30%, and 40% body mass [BM]). Sprint velocity and time were collected using a radar device and wireless photocells. Mechanical outputs were computed using a recently developed valid and reliable field method that estimates the step-averaged ground-reaction forces during overground sprint acceleration from anthropometric and spatiotemporal data. Raw velocity–time data were fitted by an exponential function and used to calculate the net horizontal ground-reaction forces and horizontal power output. Individual linear force–velocity relationships were then extrapolated to calculate the theoretical maximum horizontal force (F 0) and velocity and the ratio of force application (proportion of the total force production that is directed forward at sprint start). Results: Magnitude-based inferences showed an almost certain decrease in F 0 (effect size = 0.78–3.35), maximum power output (effect size = 0.78–3.81), and maximum ratio of force (effect size = 0.82–3.87) as the load increased. The greatest changes occurred with loads heavier than 20% BM, especially in ratio of force. In addition, the maximum power was achieved under unloaded conditions. Conclusions: Increasing load in WV sprinting affects spatiotemporal and kinetic variables. The greatest change in ratio of force happened with loads heavier than 20% BM. Thus, the authors recommend the use of loads ≤20% BM for WV sprinting.
Jorge Carlos-Vivas, Elena Marín-Cascales, Tomás T. Freitas, Jorge Perez-Gomez and Pedro E. Alcaraz
Tiago Peçanha, Marcelle Paula-Ribeiro, Edson Campana-Rezende, Rhenan Bartels, João Carlos Bouzas Marins and Jorge Roberto Perrout de Lima
It has been shown that water intake (WI) improves postexercise parasympathetic recovery after moderateintensity exercise session. However, the potential cardiovascular benefit promoted by WI has not been investigated after high-intensity exercise.
To assess the effects of WI on post high-intensity parasympathetic recovery.
Twelve recreationally active young men participated in the study (22 ± 1.4 years, 24.1 ± 1.6 kg.m−2). The experimental protocol consisted of two visits to the laboratory. Each visit consisted in the completion of a 30-min high-intensity [~80% of maximal heart rate (HR)] cycle ergometer aerobic session performing randomly the WI or control (CON, no water consumption) intervention at the end of the exercise. HR and RR intervals (RRi) were continuously recorded by a heart rate monitor before, during and after the exercise. Differences in HR recovery [e.g., absolute heart rate decrement after 1 min of recovery (HRR60s) and time-constant of the first order exponential fitting curve of the HRR (HRRτ)] and in postexercise vagalrelated heart rate variability (HRV) indexes (rMSSD30s, rMSSD, pNN50, SD1 and HF) were calculated and compared for WI and CON.
A similar HR recovery and an increased postexercise HRV [SD1 = 9.4 ± 5.9 vs. 6.0 ± 3.9 millisecond, HF(ln) = 3.6 ± 1.4 vs. 2.4 ± 1.3 millisecond2, for WI and CON, respectively; p < .05] was observed in WI compared with CON.
The results suggest that WI accelerates the postexercise parasympathetic reactivation after high-intensity exercise. Such outcome reveals an important cardioprotective effect of WI.
Blanca Roman-Viñas, Jorge Marin, Mairena Sánchez-López, Susana Aznar, Rosaura Leis, Raquel Aparicio-Ugarriza, Helmut Schroder, Rocío Ortiz-Moncada, German Vicente, Marcela González-Gross and Lluís Serra-Majem
The first Active Healthy Kids Spanish Report Card aims to gather the most robust information about physical activity (PA) and sedentary behavior of children and adolescents.
A Research Working Group of experts on PA and sport sciences was convened. A comprehensive data search, based on a review of the literature, dissertations, gray literature, and experts’ nonpublished data, was conducted to identify the best sources to grade each indicator following the procedures and methodology outlined by the Active Healthy Kids Canada Report Card model.
Overall PA (based on objective and self-reported methods) was graded as D-, Organized Sports Participation as B, Active Play as C+, Active Transportation as C, Sedentary Behavior as D, School as C, and Family and Peers as Incomplete, Community and the Built Environment as Incomplete, and Government as Incomplete.
Spanish children and adolescents showed low levels of adherence to PA and sedentary behavior guidelines, especially females and adolescents. There is a need to achieve consensus and harmonize methods to evaluate PA and sedentary behavior to monitor changes over time and to evaluate the effectiveness of policies to promote PA.