Effect of land- and aquatic-based plyometrics on spike and block reaches in young volleyball players: a pilot study

Abstract Aim: The purpose of this pilot study was to analyze the feasibility of the intervention and measures of a six-week land- and aquatic-based plyometric training on spike and block reaches in young volleyball athletes. Methods: Twelve female players were divided into a land group (LG) (n = 6, 12.4 ± 0.3 years, 1.61 ± 0.04 m, 57.0 ± 9.3 kg) and a water group (WG) (n = 6, 12.5 ± 0.5 years, 1.57 ± 0.06 m, 48.9 ± 8.5 kg). The spike and block (without step, with slide step, and with crossover step) reach and countermovement jump height were evaluated before and after a 6-week plyometric training protocol. Duration (total and of each session), adhesion and adherence, and safeness of the intervention; completion of assessments, within-trial reliability, and variability of the outcome measures and preliminary results were the variables of interest. To analyze the effect of the training on jump performance, the Wilcoxon test was used (p < 0.05), and effect sizes (r) were calculated. Results: All participants concluded the intervention and the assessments as planned. No dropouts or adverse events were registered during the study. The within-trial reliability for all assessment tests was considered excellent (ICC ≥ 0.9). Preliminary results indicate that LG improved the reach of the spike and block with the slide step; and that WG improved the spike, block with the slide step to the left, and block without movement reaches (p < 0.05; large effect size). Conclusion: An intervention of six weeks of plyometric training on land and in water is feasible, and preliminary results indicate that both training protocols may benefit the performance of spike and block in young volleyball athletes.

Comparison between side-lying and standing positions for hip abductor strength assessment.

BACKGROUND: The hip abductor muscles control the pelvis in the frontal plane and allow the maintenance of trunk position and dynamic balance during weight-bearing activities. OBJECTIVE: To compare the side-lying and standing positions for hip abductor strength assessment with regards to torque production and myolectric activity. METHOD: Concentric and eccentric hip abductor peak torque and total work, and myoelectric activity of the tensor fascia lata, gluteus medius, and inferior and superior portions of the gluteus maximus muscles were measured during maximal isokinetic tests for hip abductor strength in the side-lying and standing positions. The Wilcoxon test was used to compare variables between the positions. RESULTS: Peak torque values did not differ between side-lying and standing positions for both concentric and eccentric contraction modes (p > .05). During standing position, greater concentric total work was observed (p = .013). This position resulted in a lower activity of the tensor fascia lata muscle (p = .005) compared to side lying position. Myoelectric activity of gluteus medius, and inferior and superior portions of the gluteus maximus was similar between positions (p > .05). CONCLUSION: Both positions presented similar peak torque values and, during the standing position, a greater concentric total work and lesser activation of the tensor fascia lata was observed. Standing position can be used when emphasis on the superior portion of gluteus maximus over the tensor fascia lata is intended.

Comprehensive spatial distribution of tropical fish assemblages from multifrequency acoustics and video fulfils the island mass effect framework.

Tropical marine ecosystems are highly biodiverse and provide resources for small-scale fisheries and tourism. However, precise information on fish spatial distribution is lacking, which limits our ability to reconcile exploitation and conservation. We combined acoustics to video observations to provide a comprehensive description of fish distribution in a typical tropical environment, the Fernando de Noronha Archipelago (FNA) off Northeast Brazil. We identified and classified all acoustic echoes into ten fish assemblage and two triggerfish species. This opened up the possibility to relate the different spatial patterns to a series of environmental factors and the level of protection. We provide the first biomass estimation of the black triggerfish Melichthys niger, a key tropical player. By comparing the effects of euphotic and mesophotic reefs we show that more than the depth, the most important feature is the topography with the shelf-break as the most important hotspot. We also complete the portrait of the island mass effect revealing a clear spatial dissymmetry regarding fish distribution. Indeed, while primary productivity is higher downstream, fish concentrate upstream. The comprehensive fish distribution provided by our approach is directly usable to implement scientific-grounded Marine Spatial Planning.

Acute Effect of 2 Self-Myofascial Release Protocols on Hip and Ankle Range of Motion.

CONTEXT: Self-myofascial release (SMR) is an intervention popularly used by rehabilitation, fitness, and sports professionals to improve recovery and performance. In SMR, the athlete/patient applies pressure to the muscle and fascia using various tools, such as balls, rods, foam rolls, and massagers. OBJECTIVE: This study aimed to evaluate the acute effect of 2 SMR protocols (short term and long term) of the posterior thigh and calf muscles on hip and ankle range of motion (ROM) in physically active men. PARTICIPANTS: A total of 14 adult males (24.9 [3.2] y, 77.2 [13.2] kg, and 1.75 [0.06] m) who exercise regularly (at least twice a week, 45 min per session) participated in this study. INTERVENTIONS: Participants performed a short-term SMR protocol (2 × 10 repetitions, SSMR) and a long-term SMR protocol (2 × 20 repetitions, LSMR) of the posterior thigh (using a foam roller) and calf (using a massage stick) muscles in counterbalanced order, on 2 different days with a 48-hour interval. MAIN OUTCOME MEASURES: Ankle dorsiflexion and hip-flexion ROM, evaluated at 5 moments: pre- and post-SSMR, pre- and post-LSMR, and in the control condition, which was always performed at the first visit. RESULTS: The SMR promoted significant gains for both dorsiflexion (F1,13 =202.67, P < .001, ηp2=.94 ) and hip flexion (F1,13 = 66.46, P < .001, ηp2=.84 ), regardless of the protocol and limb analyzed. The average increase for both limbs corresponded, approximately, to 11% for ankle dorsiflexion and to 6% for and in hip flexion. CONCLUSIONS: The results suggest that SMR of the posterior thigh and calf muscles acutely increases the ROM of both hip flexion and ankle dorsiflexion and that duplicating the SMR volume from 10 to 20 repetitions per set seems not to promote additional gains.