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Effects of Gender and Foot-Landing Techniques on Lower Extremity Kinematics during Drop-Jump Landings

research Mar 14, 2019

 3-D kinematics were collected on 50 (25 male and 25 female) college-age recreational athletes selected from a sample of convenience. Separate repeated-measures ANOVAs were used to analyze each variable at three time instants (initial contact, peak vertical ground reaction force, and maximum knee flexion angle). There were no significant differences found between genders at the three instants for each variable. At initial contact, the forefoot technique (35.79° ± 11.78°) resulted in significantly (p = .001) less hip flexion than did the self-preferred (41.25° ± 12.89°) and rear foot (43.15° ± 11.77°) techniques. At peak vertical ground reaction force, the rear foot technique (26.77° ± 9.49°) presented significantly lower (p = .001) knee flexion angles as compared with forefoot (58.77° ± 20.00°) and self-preferred (54.21° ± 23.78°) techniques. A significant difference for knee...

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Fatigue Alters Lower Extremity Kinematics During a Single-Leg Stop-Jump Task

research Mar 13, 2019

Thirty healthy, physically active subjects (15 males and 15 females) Knee and hip joint kinematics were calculated utilizing three-dimensional video analysis. Each subject performed five single-leg stop-jumps before and after an exercise-to-fatigue bout. All subjects underwent a fatigue protocol using the modified Astrand protocol. Fatigue was verified using the Rating of Perceived Exertion along with the subject’s heart rate. All data were analyzed using two factor (test × gender) repeated measures ANOVA (< 0.05). Both males and females demonstrated significantly less maximal knee valgus (P = 0.038) and decreased knee flexion at initial contact (= 0.009) post-fatigue. No significant differences were identified in hip joint angles between sessions or between sexes.

The results show that fatigue developed from exhaustive running alters lower extremity kinematics during a single-leg stop-jump task. The more neutral position in...

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Want to Know How AxIT Will Help You Get Amazing Results with Your Clients?

axit Mar 12, 2019
 

Check out what accredited Exercise Physiologist and Myotherapist - Nathan had to say from his first interactions with the AxIT system.

Don't delay. 

The response to the launch of the AxIT system has been HUGE and places on our next allocations are going fast.

Go to http://www.strengthbynumbers.com/discoverysession to book a time to find out how the AxIT system can bring your assessment into the 21st century!

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How Quick Can You Start Testing with AxIT?

axit Mar 12, 2019
 

How quick can you start testing with AxIT? Let's join Andrew and Steve to find out!

Stop Guessing and Start Measuring. Pull your assessments to the 21st century.

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Normative Data of Vertical Ground Reaction Forces During Landing From a Jump

research Mar 11, 2019

Subjects were 234 adolescents (mean age: 16 years) who were categorised by gender, activity level and type of sport played. Subjects jumped from a box 0.3 metres high to land on a force plate. Results showed that there were no significant differences (p>0.05) across gender, activity levels, and type of sport played. Across all subjects, the mean peak vertical GRF was 4.5 bodyweights (SD: 1.7). In regard to gender, mean peak vertical GRFs were 4.6 (SD:1.7) and 4.2 (SD:1.4) for males and females respectively. The mean peak vertical GRF for subjects involved in recreational sport 1–3 times per week was 4.4 bodyweights (SD:1.7), while the mean for those playing competitive sport 4–7 times per week was 4.5 bodyweights (SD: 1.7). The mean peak vertical GRF for subjects participating in sports involving jumping and landing activities was 4.6 bodyweights (SD: 1.8) as compared to 4.4 bodyweights (SD: 1.5) for subjects in sports that did not involve jumping activities.

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Augmented Feedback Reduces Jump Landing Forces

research Mar 11, 2019

Nonimpaired college students (N = 63) were randomly assigned to 1 of 4 feedback groups. Subjects were instructed to perform maximal vertical jumps onto a force plate for 3 testing sessions (baseline, 2-minute post-test, and 1-week post-test). Three feedback groups (augmented, sensory, and control I) were tested during all 3 testing sessions, while a fourth feedback group (control II) was evaluated at only 2 sessions (baseline and 1-week post-test). Subjects in the augmented feedback condition were provided information via video and verbal analysis of how to land softer. Subjects in the sensory feedback condition were asked to use the experience of their baseline jumps to document how they could land softer. Subjects in each of the control groups were not provided any extraneous feedback. Peak vertical ground reaction force data were collected for analysis.

The subjects in the augmented feedback group significantly reduced their peak vertical ground reaction force in both...

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AxIT will make you, Jump, Jump....into the future of assessment

Uncategorized Mar 10, 2019
 
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Effects of Load on Ground Reaction Force and Lower Limb Kinematics During Concentric Squats

research Mar 10, 2019

The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1±0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67±0.20 to 3.21±0.29 times body weight and increased significantly as external load increased (P<0.05). Bar linear velocity ranged from 0.54±0.11 to 2.50±0.50 m·s−1 and decreased significantly with increasing external load (P<0.05). Hip, knee and ankle angles at maximum ground reaction force were affected by external load (P<0.05). The force–barbell velocity curves were fitted using linear models with coefficients (r...

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The Relationship Between Maximal Jump-Squat Power and Sprint Acceleration in Athletes

research Mar 09, 2019

Thirty male athletes [height: 183.8 (6.8) cm, and mass: 90.6 (9.3) kg; mean (SD)] each completed six 10-m sprints from a standing start. Sprint times were recorded using a tethered running system and the force-time characteristics of the first ground contact were recorded using a recessed force plate. Three to six days later subjects completed three concentric jump squats, using a traditional and split technique, at a range of external loads from 30–70% of one repetition maximum (1RM)

Average power was maximal at all loads between 30% and 60% of 1RM for both squats. Split squat peak power was also maximal between 30% and 60% of 1RM; however, traditional squat peak power was maximal between 50% and 70% of 1RM. Concentric force development is critical to sprint start performance and accordingly maximal concentric jump power is related to sprint acceleration.

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Lower Limb Asymmetry in Mechanical Muscle Function: A Comparison Between Ski Racers With and Without ACL Reconstruction

research Mar 08, 2019

Due to a high incidence of anterior cruciate ligament (ACL) re‐injury in alpine ski racers, this study aims to assess functional asymmetry in the countermovement jump (CMJ), squat jump (SJ), and leg muscle mass in elite ski racers with and without anterior cruciate ligament reconstruction (ACL‐R). Elite alpine skiers with ACL‐R (n = 9; 26.2 ± 11.8 months post‐op) and uninjured skiers (n = 9) participated in neuromuscular screening. Vertical ground reaction force during the CMJ and SJ was assessed using dual force plate methodology to obtain phase‐specific bilateral asymmetry indices (AIs) for kinetic impulse (CMJ and SJ phase‐specific kinetic impulse AI). Dual x‐ray absorptiometry scanning was used to assess asymmetry in lower body muscle mass. Compared with controls, ACL‐R skiers had increased AI in muscle mass (P < 0.001), kinetic impulse AI in the CMJ concentric phase (P < 0.05), and the final...

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