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Despite previous support for plyometric training, optimal dosing strategies remain unclear. Purpose: To investigate vertical and horizontal jump kinetic performance following a low-volume plyometric stimulus with progressively increased session jump volume. Methods: Sixteen academy rugby players (20.0 [2.0] y; 103.0 [17.6] kg; 184.3 [5.5] cm) volunteered for this study. Vertical and horizontal jump sessions were conducted 1 week apart and consisted of a 40-jump low-volume plyometric stimulus using 4 exercises, after which volume was progressively increased to 200 jumps, using countermovement jump (CMJ) for vertical sessions and horizontal broad jump (HBJ) for horizontal sessions. Jump performance was assessed via force-plate analysis at baseline (PRE-0), following the low-volume plyometric stimulus (P-40), and every subsequent 10 jumps until the end of the session (P-50, P-60, P-70,... P-200). Results: The low-volume stimulus was effective in potentiating HBJ (2% to 5%) but not CMJ (0% to −7%) performance (P <.001). The HBJ performance enhancements were maintained throughout the entire high-volume session, while CMJ realized small but significant decrements (−5% to −7%) in jump height P-50 to P-80 before recovering to presession values. Moreover, increases in eccentric impulse (5% to 24%; P <.001) in both sessions were associated with decreased or maintained concentric impulse, indicating a breakdown in performance-augmenting mechanisms and less effective power transfer concentrically after moderate volumes. Conclusion: Practitioners should consider kinetic differences between HBJ and CMJ with increasing volume to better inform and understand session dosing strategies. [ABSTRACT FROM AUTHOR]

This study determined the acute changes in rotational work with thigh attached wearable resistance (WR) of 2% body mass during 50-m sprint-running. Fourteen athletes completed sprints with, and without, WR in a randomised order. Sprint times were measured via timing gates at 10-m and 50-m. Rotational kinematics were obtained over three phases (steps 1–2, 3–6 and 7–10) via inertial measurement unit attached to the left thigh. Quantification of thigh angular displacement and peak thigh angular velocity was subsequently derived to measure rotational work. The WR condition was found to increase sprint times at 10-m (1.4%, effect size [ES] 0.38, p 0.06) and 50-m (1.9%, ES 0.55, p 0.04). The WR condition resulted in trivial to small increases in angular displacement of the thigh during all phases (0.6–3.4%, ES 0.04–0.26, p 0.09–0.91). A significant decrease in angular velocity of the thigh was found in all step phases (−2.5% to −8.0%, ES 0.17–0.51, p < 0.001–0.04), except extension in step phase 1 with the WR. Rotational work was increased (9.8–18.8%, ES 0.35–0.53, p < 0.001) with WR in all phases of the sprint. Thigh attached WR provides a means to significantly increase rotational work specific to sprinting. [ABSTRACT FROM AUTHOR]

This study determined the acute changes in spatio-temporal and impulse variables when wearable resistance (WR) of 2% body mass was attached distally to the thighs during 50 m maximal sprint-running. Fifteen sub-elite male sprinters performed sprints with and without WR over 50 m of in-ground force platforms in a randomised order. A paired t-test was used to determine statistical differences (p <.05), with effect sizes (ES) calculated between conditions over steps: 1–4, 5–14, and 15–23. WR resulted in small increased 10 and 50 m sprint times (1.0%, ES = 0.31, 0.9%, ES = 0.44, respectively, p >.05) compared to the unloaded sprint condition. For spatio-temporal variables, the WR condition resulted in moderate ES changes in step frequency (−2.8%, ES = −0.53, steps 5–14, p >.05), and contact time (2.5%, ES = 0.57, steps 5–14, and 3.2%, ES = 0.51, average of 23 steps, p >.05), while step length was unaffected during all step phases of the sprint (ES = 0.02–0.07, p >.05). Regarding kinetics, during steps 5–14, WR resulted in a moderate decrease (−4.8%, ES = −0.73, p <.05) in net anterior-posterior impulses and a moderate decrease in vertical stiffness (−5.7%, ES = −0.57, p >.05). For athletes seeking to overload step frequency and develop anterior-posterior impulse during mid to late accelerated sprinting, WR enables the application of a sprint-specific form of resistance training to be completed without decreasing step length. [ABSTRACT FROM AUTHOR]