Novel Assessment of Isometric Hip Extensor Function: Reliability, Joint Angle Sensitivity, and Concurrent Validity.

Goodwin, JE and Bull, AMJ. Novel assessment of isometric hip extensor function: reliability, joint angle sensitivity, and concurrent validity. J Strength Cond Res 36(10): 2762-2770, 2022-Closed-chain hip extension function has not been well examined.

Speed Demands of Women's Rugby Sevens Match Play.

Misseldine, ND, Blagrove, RC, and Goodwin, JE. Speed demands of women's rugby sevens match play. J Strength Cond Res 35(1): 183-189, 2021-The purpose of this study was to quantify the running speed demands of elite female rugby sevens match play, both absolute and relative to maximal ability, and determine the importance of maximal velocity running to performance.

The effects of acute static and dynamic stretching on spring-mass leg stiffness.

Objective: This study investigated the effect of brief static and dynamic stretching on spring-mass leg stiffness in a vertical bilateral hopping task.

Method: 38 men and 18 women were randomly assigned to either a natural (NAT; n = 27), or maximal (MAX; n = 29) hopping group. NAT bounced at their self-selected stiffness and MAX were instructed to bounce as stiffly as possible.

Effects of an 8-week strength training intervention on tibiofemoral joint loading during landing: a cohort study.

Objectives: To use a musculoskeletal model of the lower limb to evaluate the effect of a strength training intervention on the muscle and joint contact forces experienced by untrained women during landing.

Methods: Sixteen untrained women between 18 and 28 years participated in this cohort study, split equally between intervention and control groups. The intervention group trained for 8 weeks targeting improvements in posterior leg strength.

The effect of weightlifting shoes on the kinetics and kinematics of the back squat.

Weightlifting shoes (WS) are often used by athletes to facilitate their squat technique; however, the nature of these benefits is not well understood. In this study, the effects of footwear and load on the mechanics of squatting were assessed for 32 participants (age: 25.4 ± 4.

Relative Intensity Influences the Degree of Correspondence of Jump Squats and Push Jerks to Countermovement Jumps.

The aim of this study was to determine the mechanical similarity between push jerk (PJ) and jump squat (JS) to countermovement jump (CMJ) and further understand the effect increasing external load may have on this relationship. Eight physically trained men (age 22 ± 3; height 176 ± 7 kg; weight 83 ± 8 kg) performed an unloaded CMJ followed by JS under a range of loads (10, 25, 35, and 50% 1RM back squat) and PJ (30, 50, 65, and 75% 1RM push jerk). A portable force platform and high-speed camera both collecting at 250 Hz were used to establish joint moments and impulse during the propulsive phase of the movements.

Peak Power Output in the Bench Pull Is Maximized After Four Weeks of Specific Power Training.

Maximal power production has been shown to be a differentiating factor between playing levels in many sports and is thus a focus of many strength and conditioning programmes. We sought to evaluate the duration for which a strategy of training with the optimal load (that maximizes power output) will be effective in producing improvements in power output in the bench pull (BP). The optimal load that produced the maximum power output in the BP was determined for 21 male university athletes who were randomly assigned to a group that trained with their optimal load or a load 10% of their 1 repetition maximum below the optimal load.

Hip and knee joint loading during vertical jumping and push jerking.

Background: The internal joint contact forces experienced at the lower limb have been frequently studied in activities of daily living and rehabilitation activities. In contrast, the forces experienced during more dynamic activities are not well understood, and those studies that do exist suggest very high degrees of joint loading.

Methods: In this study a biomechanical model of the right lower limb was used to calculate the internal joint forces experienced by the lower limb during vertical jumping, landing and push jerking (an explosive exercise derived from the sport of Olympic weightlifting), with a particular emphasis on the forces experienced by the knee.

Intersegmental moment analysis characterizes the partial correspondence of jumping and jerking.

The aim of this study was to quantify internal joint moments of the lower limb during vertical jumping and the weightlifting jerk to improve awareness of the control strategies and correspondence between these activities, and to facilitate understanding of the likely transfer of training effects. Athletic men completed maximal unloaded vertical jumps (n = 12) and explosive push jerks at 40 kg (n = 9). Kinematic data were collected using optical motion tracking and kinetic data via a force plate, both at 200 Hz.

An optimization approach to inverse dynamics provides insight as to the function of the biarticular muscles during vertical jumping.

Traditional inverse dynamics approaches to calculating the inter-segmental moments are limited in their ability to accurately reflect the function of the biarticular muscles. In particular they are based on the assumption that the net inter-segmental moment is zero and that total joint moments are independent of muscular activity. Traditional approaches to calculating muscular forces from the inter-segmental moments are based on a consideration of joint moments which do not encapsulate the potential moment asymmetry between segments.

Caffeine supplementation and multiple sprint running performance.

Purpose: The aim of this study was to examine the effects of caffeine supplementation on multiple sprint running performance.

Methods: Using a randomized double-blind research design, 21 physically active men ingested a gelatin capsule containing either caffeine (5 mg x kg(-1) body mass) or placebo (maltodextrin) 1 h before completing an indoor multiple sprint running trial (12 x 30 m; repeated at 35-s intervals). Venous blood samples were drawn to evaluate plasma caffeine and primary metabolite concentrations.

Effect of pre-performance lower-limb massage on thirty-meter sprint running.

Massage is a commonly utilized therapy within sports, frequently intended as an ergogenic aid prior to performance. However, evidence as to the efficacy of massage in this respect is lacking, and massage may in some instances reduce force production. The aim of this study was to investigate the effect of massage on subsequent 30-m sprint running performance.

Familiarization and reliability of multiple sprint running performance indices.

The aims of this study were to evaluate the time-course of the familiarization process associated with a test of multiple sprint running performance and to determine the reliability of various performance indices once familiarization had been established. Eleven physically active men (mean age: 21 +/- 2 years) completed 4 multiple sprint running trials (12 x 30 m; repeated at 35-s intervals) with 7 days between trials. All testing was conducted indoors, and times were recorded by twin-beam photocells.

Creatine supplementation and multiple sprint running performance.

The aim of this study was to examine the effects of short-term creatine monohydrate supplementation on multiple sprint running performance. Using a double-blind research design, 42 physically active men completed a series of 3 indoor multiple sprint running trials (15 x 30 m repeated at 35-second intervals). After the first 2 trials (familiarization and baseline), subjects were matched for fatigue score before being randomly assigned to 5 days of either creatine (4 x d(-1) x 5 g creatine monohydrate + 1 g maltodextrin) or placebo (4 x d(-1) x 6 g maltodextrin) supplementation.