Department of Sport, Exercise and Rehabilitation, Northumbria University, United Kingdom.
Published: February 2019
AI Article Synopsis
Article Abstract
Objectives: To determine the effect of performing depth jumps (DJ) pre-exercise on running economy (RE) and time to exhaustion (TTE) at the speed associated with maximal oxygen uptake (sV˙O) in a group of high-performing junior middle-distance runners.
Design: Randomized crossover study.
Methods: Seventeen national- and international-standard male distance runners (17.6±1.2years, 63.4±6.3kg, 1.76±0.06m, 70.7±5.2mLkgmin) completed two trials. Following a 5min warm-up at 60% V˙O, participants performed a 5min run at 20%Δ below oxygen uptake corresponding with lactate turn-point to determine pre-intervention RE. Participants then completed either six DJ from a box equivalent to their best counter-movement jump (CMJ) or a control condition (C) involving body weight quarter squats. After a 10min passive recovery, another 5min sub-maximal run was performed followed by a run to exhaustion at sV˙O.
Results: Compared to the C trial, DJ produced moderate improvements (-3.7%, 95% confidence interval for effect size: 0.25-1.09) in RE, which within the context of minimal detectable change is considered possibly beneficial. Differences in TTE and other physiological variables were most likely trivial (ES: <0.2). Individual responses were small, however a partial correlation revealed a moderate relationship (r=-0.55, p=0.028) between change in RE and CMJ height.
Conclusions: The inclusion of a set of six DJ in the warm-up routine of a well-trained young male middle-distance runner is likely to provide a moderate improvement in RE.
Purpose: The present study aimed to evaluate and compare the management of Jump space (JS) in immediate implants with and without Demineralised freeze-dried bone allograft (DFDBA) with flapless approach.
Materials And Methods: The present study included 40 sites with immediate implant placement in the maxillary anterior region. Group 1 patients were treated without augmentation while Group 2 patients with DFDBA in the JS.
The study examined how changes in braking rate of force development (B-RFD) and amortization force (Amf) during countermovement jumps (CMJs) affect jump height in 19 trained participants.
Results showed significant effects of jump velocity and depth on B-RFD and Amf, but no notable impact on CMJ height.
Furthermore, while improvements in B-RFD and Amf correlated with enhanced early impulse (EI), they did not lead to increased CMJ height, indicating that enhancing these factors alone doesn't guarantee higher jumps.
Movement-Interactions-Performance, MIP, UR 4334, Le Mans Université, Le Mans, France; Laboratoire IRISSE, UFR des Sciences de l'Homme et de l'Environnement, Université de la Réunion, Le Tampon, Ile de la Réunion, France.
The study examined how different push-off distances affect the maximum height of jumps among CrossFit athletes during countermovement jumps.
Results indicated a quadratic relationship between push-off distance and jump height, revealing that each athlete has an optimal push-off distance for maximizing their jump.
Additionally, longer push-off distances increased push-off time and decreased mean vertical external force, affecting overall jump performance by altering joint angles and torque production in the process.
To accurately understand the deformation behavior of surrounding rock in the jiugongshan No.2 high ground stress tunnel and optimize construction parameters for improved efficiency, on-site monitoring was used to gather data on rock deformation and initial support contact pressure. A WOA-LSTM regression prediction model was proposed, and excavation advance depth was optimized using numerical simulation.
