scholarly journals The biomechanical characteristics of the strongman atlas stone lift

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12066
Author(s):  
Benjamin Hindle ◽  
Anna Lorimer ◽  
Paul Winwood ◽  
Daniel Brimm ◽  
Justin W.L. Keogh
Keyword(s):  
Knee Flexion ◽  
Female Athletes ◽  
Knee Extension ◽  
Ankle Dorsiflexion ◽  
Strength And Conditioning ◽  
Phase Duration ◽  
Male Athletes ◽  
Kinematic Measures ◽  
Temporal Measures ◽  
Hip Flexion

Background The atlas stone lift is a popular strongman exercise where athletes are required to pick up a large, spherical, concrete stone and pass it over a bar or place it on to a ledge. The aim of this study was to use ecologically realistic training loads and set formats to (1) establish the preliminary biomechanical characteristics of athletes performing the atlas stone lift; (2) identify any biomechanical differences between male and female athletes performing the atlas stone lift; and (3) determine temporal and kinematic differences between repetitions of a set of atlas stones of incremental mass. Methods Kinematic measures of hip, knee and ankle joint angle, and temporal measures of phase and repetition duration were collected whilst 20 experienced strongman athletes (female: n = 8, male: n = 12) performed three sets of four stone lifts of incremental mass (up to 85% one repetition maximum) over a fixed-height bar. Results The atlas stone lift was categorised in to five phases: the recovery, initial grip, first pull, lap and second pull phase. The atlas stone lift could be biomechanically characterised by maximal hip and moderate knee flexion and ankle dorsiflexion at the beginning of the first pull; moderate hip and knee flexion and moderate ankle plantarflexion at the beginning of the lap phase; moderate hip and maximal knee flexion and ankle dorsiflexion at the beginning of the second pull phase; and maximal hip, knee extension and ankle plantarflexion at lift completion. When compared with male athletes, female athletes most notably exhibited: greater hip flexion at the beginning of the first pull, lap and second pull phase and at lift completion; and a shorter second pull phase duration. Independent of sex, first pull and lap phase hip and ankle range of motion (ROM) were generally smaller in repetition one than the final three repetitions, while phase and total repetition duration increased throughout the set. Two-way interactions between sex and repetition were identified. Male athletes displayed smaller hip ROM during the second pull phase of the first three repetitions when compared with the final repetition and smaller hip extension at lift completion during the first two repetitions when compared with the final two repetitions. Female athletes did not display these between-repetition differences. Conclusions Some of the between-sex biomechanical differences observed were suggested to be the result of between-sex anthropometric differences. Between-repetition differences observed may be attributed to the increase in stone mass and acute fatigue. The biomechanical characteristics of the atlas stone lift shared similarities with the previously researched Romanian deadlift and front squat. Strongman athletes, coaches and strength and conditioning coaches are recommended to take advantage of these similarities to achieve greater training adaptations and thus performance in the atlas stone lift and its similar movements.

scholarly journals Gender Differences in Kinematic Analysis of the Lower Limbs during the Chasse Step in Table Tennis Athletes

Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 703
Author(s):  
Xiaoyi Yang ◽  
Yuqi He ◽  
Shirui Shao ◽  
Julien S. Baker ◽  
Bíró István ◽  
...  
Keyword(s):  
Female Athletes ◽  
External Rotation ◽  
Rotational Velocity ◽  
Knee Extension ◽  
Lower Limbs ◽  
Table Tennis ◽  
Male Athletes ◽  
Analysis System ◽  
Hip Flexion ◽  
Hip Internal Rotation

The chasse step is one of the most important footwork maneuvers used in table tennis. The purpose of this study was to investigate the lower limb kinematic differences of table tennis athletes of different genders when using the chasse step. The 3D VICON motion analysis system was used to capture related kinematics data. The main finding of this study was that the step times for male athletes (MA) were shorter in the backward phase (BP) and significantly longer in the forward phase (FP) than for female athletes (FA) during the chasse step. Compared with FA, knee external rotation for MA was larger during the BP. MA showed a smaller knee flexion range of motion (ROM) in the BP and larger knee extension ROM in the FP. Moreover, hip flexion and adduction for MA were significantly greater than for FA. In the FP, the internal rotational velocity of the hip joint was significantly greater. MA showed larger hip internal rotation ROM in the FP but smaller hip external rotation ROM in the BP. The differences between genders can help coaches personalize their training programs and improve the performance of both male and female table tennis athletes.

scholarly journals Development of an on-field injury screening test using wearable sensor technology

2020 ◽  
Vol 8 (9_suppl7) ◽  
pp. 2325967120S0051
Author(s):  
Pinar Melodi Caliskan ◽  
Anne Benjaminse ◽  
Alli Gokeler
Keyword(s):  
Knee Flexion ◽  
Motor Coordination ◽  
Knee Extension ◽  
Ankle Dorsiflexion ◽  
Hip Abduction ◽  
Knee Abduction ◽  
Hip Flexion ◽  
Injury Screening ◽  
Coordination Patterns ◽  
Hip Extension

Introduction: Injuries of the anterior cruciate ligament (ACL) commonly occur during complex game situations when the athlete encounters multiple factors such as ball, opponent, field position, and game strategy (Grooms et al., 2018). Many of the current traditional injury screening programs are performed within a predictable, fixed or ‘closed’ environment which do not represent real game situations that require high neurocognitive demands (Dingenen & Gokeler, 2017; Grooms et al., 2018). A complementary approach to lab-based settings is necessary to incorporate the demands of the complex athletic environments. By using wearable sensor technology, we aim to develop an on-field injury screening test in elite youth male soccer players. Investigating the individual differences in motor coordination patterns of the players during sport-specific tasks might enhance our understanding of how ACL injuries occur. Hypotheses: We hypothesized that the motor coordination patterns of the players would be affected when they perform under different conditions manipulated with constraints (task and environmental). Methods: A football-specific test setup was created to analyse the kinematic and performance measures of a group of 17 male youth elite football players aged 15 years (height = 164 ± 9 cm, mass = 50.9± 7.4 kg). The players were grouped into two and measured on two consecutive days. All the players were instructed to complete the test setup (4 conditions, 5 trials) as fast as possible. Condition 1 includes no constraint, condition 2 includes a task constraint (football dummies), condition 3 includes an environmental constraint (stroboscopic glasses) (SENAPTEC, Beaverton, Oregon) and condition 4 includes both task and environmental constraints. 3-D kinematics of the hip, knee, ankle joints were captured using Xsens wearable full-body sensor suits (Xsens, MVN Link version, Enschede, The Netherlands). MATLAB (MATLAB R2019a, The MathWorks Inc., Massachusetts) was used to process and analyse the kinematic data. Data from condition 1 was determined as reference behavior/condition to be compared to other conditions. Kinematic data are presented in attitude vectors (ATV). Results: In total, 81% of the players demonstrated a significant difference (P < 0.05) in angles of hip, knee and ankle joints when performing under different conditions. The percentage of players with increased comparison-based joint movements as follows; condition 1 to condition 2 comparison; 41% hip flexion, 59% hip extension, 53% hip abduction, 47% hip adduction, 62% knee flexion, 38% knee extension, 59% knee abduction, 41% knee adduction, 47% ankle dorsiflexion, 53% ankle plantarflexion, condition 1 to condition 3 comparison; 35% hip flexion, 65% hip extension, 47% hip abduction, 53% hip adduction, 50% knee flexion, 50% knee extension, 41% knee abduction, 59% knee adduction, 59% ankle dorsiflexion, 41% ankle plantarflexion and condition 1 to condition 4 comparison; 31% hip flexion, 69% hip extension, 38% hip abduction, 62% hip adduction, 60% knee flexion, 40% knee extension, 44% knee abduction, 56% knee adduction, 69% ankle dorsiflexion, 31% ankle plantarflexion. Conclusion: The result of this pilot study demonstrated that manipulating task with different constraints caused significant changes in players’ motor coordination patterns which supported the hypothesis of our study. Our findings suggest to develop ACL injury screening tests in a sport-specific setting.

scholarly journals Midterm outcome and strength assessment after proximal rectus femoris refixation in athletes

2021 ◽  
Author(s):  
Maximilian Hinz ◽  
Stephanie Geyer ◽  
Felix Winden ◽  
Alexander Braunsperger ◽  
Florian Kreuzpointner ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Harris Hip Score ◽  
Postoperative Results ◽  
Postoperative Result ◽  
Strength Assessment ◽  
Competitive Athletes ◽  
Hip Flexion

Abstract Purpose Proximal rectus femoris avulsions (PRFA) are relatively rare injuries that occur predominantly among young soccer players. The aim of this study was to evaluate midterm postoperative results including strength potential via standardized strength measurements after proximal rectus femoris tendon refixation. It was hypothesized that the majority of competitive athletes return to competition (RTC) after refixation of the rectus femoris tendon without significant strength or functional deficits compared to the contralateral side. Methods Patients with an acute (< 6 weeks) PRFA who underwent surgical refixation between 2012 and 2019 with a minimum follow-up of 12 months were evaluated. The outcome measures compiled were the median Tegner Activity Scale (TAS) and mean RTC time frames, Harris Hip Score (HHS), Hip and Groin Outcome Score (HAGOS) subscales, International Hip Outcome Tool-33 (iHOT-33), and Visual Analog Scale (VAS) for pain. In addition, a standardized isometric strength assessment of knee flexion, knee extension, and hip flexion was performed to evaluate the functional result of the injured limb in comparison to the uninjured side. Results Out of 20 patients, 16 (80%) patients were available for final assessment at a mean follow-up of 44.8 ± SD 28.9 months. All patients were male with 87.5% sustaining injuries while playing soccer. The average time interval between trauma and surgery was 18.4 ± 8.5 days. RTC was possible for 14 out of 15 previously competitive athletes (93.3%) at a mean 10.5 ± 3.4 months after trauma. Patients achieved a high level of activity postoperatively with a median (interquartile range) TAS of 9 (7–9) and reported good to excellent outcome scores (HHS: 100 (96–100); HAGOS: symptoms 94.6 (89.3–100), pain 97.5 (92.5–100), function in daily living 100 (95–100), function in sport and recreation 98.4 (87.5–100), participation in physical activities 100 (87.5–100), quality of life 83.1 ± 15.6; iHot-33: 95.1 (81.6–99.8)). No postoperative complications were reported. Range of motion, isometric knee flexion and extension, as well as hip flexion strength levels were not statistically different between the affected and contralateral legs. The majority of patients were “very satisfied” (56.3%) or “satisfied” (37.5%) with the postoperative result and reported little pain (VAS 0 (0–0.5)). Conclusion Surgical treatment of acute PRFA yields excellent postoperative results in a young and highly active cohort. Hip flexion and knee extension strength was restored fully without major surgical complications. Level of evidence Retrospective cohort study; III.

Spinal Curvature and Lower Extremities Kinematics of Simulated Pregnancy during Stair Ascending and Descending

2019 ◽  
Vol 41 ◽  
pp. 11-22
Author(s):  
Ihssan S. Masad ◽  
Sami Almashaqbeh ◽  
Othman Smadi ◽  
Mariam Abu Olaim ◽  
Abeer Obeid
Keyword(s):  
Knee Flexion ◽  
Lower Extremities ◽  
Ankle Dorsiflexion ◽  
Spinal Curvature ◽  
Control Group ◽  
Group Data ◽  
Significant Difference ◽  
Position Data ◽  
Infrared Cameras ◽  
Hip Flexion

The purpose of this work is to investigate the effect of anteriorly-added mass to simulate pregnancy on lower extremities kinematic and lumbar and thoracic angles during stair ascending and descending. 18 healthy females ascended and descended, with and without a pseudo-pregnancy sac of 12 kg (experimental and control groups, respectively), a costume-made wooden staircase while instrumented with 20 reflective markers placed on the lower extremities and the spine. The movements were captured by 12 infrared cameras surrounding the staircase. Tracked position data were exported to MATLAB to calculate the required joints angles. SPSS was used to compare the ascent and descent phases of control group, and to find if there are any significant differences between control and experimental groups in the ascent phase as well as in the descent phase. When comparing the ascent and descent phases of control group, data revealed a higher hip flexion during ascending and greater ankle planter-flexion and dorsiflexion, lumbar, and thoracic angles during descending; however, no significant difference was shown in the knee flexion angle between ascending and descending. Non-pregnant data showed greater maximum hip flexion and ankle dorsiflexion during stair ascending compared to simulated-pregnant group; while ankle planter-flexion, knee flexion, and lumbar angle were greater for simulated-pregnant status. During stair descending, non-pregnant group had greater minimum hip flexion and ankle dorsiflexion compared to simulated pregnant group; while ankle planter-flexion, knee flexion, and maximum hip flexion were greater for simulated-pregnant group. However, the lumbar and thoracic angles were found to be similar for simulated-pregnant and non-pregnant groups during stair descending. In conclusion, the current study revealed important kinematic modifications pregnant women adopt while ascending and descending stairs at their final stage of pregnancy to increase their stability.

Nutrition Knowledge, Opinions, and Practices of Coaches and Athletic Trainers at a Division I University

2001 ◽  
Vol 11 (2) ◽  
pp. 174-185 ◽  
Author(s):  
Michelle Smith Rockwell ◽  
Sharon M. Nickols-Richardson ◽  
Forrest W. Thye
Keyword(s):  
Female Athletes ◽  
Athletic Trainers ◽  
Nutrition Knowledge ◽  
Division I ◽  
Registered Dietitians ◽  
Strength And Conditioning ◽  
Male Athletes ◽  
Nutritional Recommendations ◽  
Better Than ◽  
Analyze Data

The purpose of this investigation was to assess nutrition knowledge, opinions, and practices of coaches and trainers at a Division I university. Participants (n = 53) completed questionnaires regarding nutrition knowledge, opinions, and practices. Descriptive statistics and analysis of variance were used to analyze data. Overall, participants responded correctly to 67% of nutrition knowledge questions. Participants who coached/trained female athletes tended to score better than respondents who coached/trained male athletes. Strength and conditioning coaches and participants with greater than 15 years of experience scored higher than other participants. Nutrition opinions/practices responses revealed that nutritional supplements were provided for all but 6% of participants’ athletes. Participants rated body weight as more important than body composition to athletes’ performances. Over 30% of participants perceived at least one case of disordered eating within the past year. Some participants (53%) felt that athletes may consume more nutritious meals on team-sponsored trips if given larger food allowances. Thirty percent of participants reported dietitians were available to them; the same percentage reported utilizing dietitians. Coaches and trainers are knowledgeable about some appropriate nutritional recommendations, but registered dietitians or qualified sports nutrition professionals may complement the nutrition-related education and counseling of athletes (23).

Effect of Frequency on Human Unipedal Hopping

2002 ◽  
Vol 95 (3) ◽  
pp. 733-740 ◽  
Author(s):  
Gary P. Austin ◽  
David Tiberio ◽  
Gladys E. Garrett
Keyword(s):  
Lower Extremity ◽  
Knee Flexion ◽  
Lower Extremities ◽  
Ankle Dorsiflexion ◽  
Vertical Force ◽  
Two Dimensional ◽  
Vertical Stiffness ◽  
Hip Flexion ◽  
Force Displacement ◽  
Healthy Males

All mature forms of locomotion involve periods of unilateral stance. Unipedal hopping may provide useful information about the neuromuscular and biomechanical capabilities of a single lower extremity in adults. This study investigated whether hopping influenced vertical stiffness and lower extremity angular kinematics during human unipedal hopping. Vertical force and two-dimensional kinematics were measured in 10 healthy males hopping at three frequencies: preferred, +20%, and −20%. At +20%, compared to preferred, vertical stiffness increased 55% as hip flexion, knee flexion, and ankle dorsiflexion decreased, while at −20% vertical stiffness decreased 39.4% as hip flexion, knee flexion, and ankle dorsiflexion increased. As in bipedal hopping, the force-displacement relationship was more springlike at the preferred rate and +20% than at −20%. Given the prevalence of unilateral stance during walking, running, and skipping, findings related to unipedal hopping may be useful in the rehabilitation or conditioning of lower extremities.

scholarly journals Effects of Hip Flexion on Knee Extension and Flexion Isokinetic Angle-Specific Torques and HQ-Ratios

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Christian Baumgart ◽  
Eduard Kurz ◽  
Jürgen Freiwald ◽  
Matthias Wilhelm Hoppe
Keyword(s):  
Hip Joint ◽  
Knee Flexion ◽  
Daily Life ◽  
Knee Extension ◽  
Flexion Angle ◽  
Strength Testing ◽  
Knee Strength ◽  
Sporting Activities ◽  
Torque Values ◽  
Hip Flexion

Abstract Background and Methods During isokinetic knee strength testing, the knee flexion angles that correspond to the measured torque values are rarely considered. Additionally, the hip flexion angle during seated testing diverges from that in the majority of daily life and sporting activities. Limited information concerning the influence of hip angle, muscle contraction mode, and velocity on the isokinetic knee strength over the entire range of motion (ROM) is available. Twenty recreational athletes (10 females, 10 males; 23.3 ± 3.2 years; 72.1 ± 16.5 kg; 1.78 ± 0.07 m) were tested for isokinetic knee flexion and extension at 10° and 90° hip flexion with the following conditions: (i) concentric at 60°/s, (ii) concentric at 180°/s, and (iii) eccentric at 60°/s. The effects of hip angle, contraction mode, and velocity on angle-specific torques and HQ-ratios as well as conventional parameters (peak torques, angles at peak torque, and HQ-ratios) were analyzed using statistical parametric mapping and parametric ANOVAs, respectively. Results Generally, the angle-specific and conventional torques and HQ-ratios were lower in the extended hip compared to a flexed hip joint. Thereby, in comparison to the knee extension, the torque values decreased to a greater extent during knee flexion but not consistent over the entire ROM. The torque values were greater at the lower velocity and eccentric mode, but the influence of the velocity and contraction mode were lower at shorter and greater muscle lengths, respectively. Conclusions Isokinetic knee strength is influenced by the hip flexion angle. Therefore, a seated position during testing and training is questionable, because the hip joint is rarely flexed at 90° during daily life and sporting activities. Maximum knee strength is lower in supine position, which should be considered for training and testing. The angle-specific effects cannot be mirrored by the conventional parameters. Therefore, angle-specific analyses are recommended to obtain supplemental information and consequently to improve knee strength testing.

scholarly journals Influence of prophylactic ankle tapes on lower-extremity kinematics during a stop-jump task in chronic ankle instability

2021 ◽  
Keyword(s):  
Lower Extremity ◽  
Knee Flexion ◽  
Ankle Instability ◽  
Three Dimensional ◽  
Lower Extremities ◽  
Chronic Ankle Instability ◽  
Ankle Dorsiflexion ◽  
Ankle Inversion ◽  
Motion System ◽  
Hip Flexion

Background and objective: Numerous tape applications have been used in patients with chronic ankle instability (CAI). However, the effect of prophylactic ankle taping on lower-extremity kinematics is still not well understood. This study aimed to investigate the effects of traditional taping, fibular repositioning taping, and kinesiology taping on the peak angles of the lower extremities in patients with CAI. Materials and Methods: A total of 14 men (age, 24.07 ± 4.46 years; height, 175.06 ± 5.10 cm; weight, 82.24 ± 10.38 kg (mean ± standard deviation)) with CAI identified using screening questionnaires (Cumberland Ankle Instability Tool, 17.64 ± 4.14; Foot and Ankle Ability Measure (FAAM) Activity of Daily Living, 86.69 ± 6.71; and FAAM Sports Subscale, 75.45 ± 6.70) participated. The peak angles of the hip, knee, and ankle joints during a stop-jump task, with and without tape application, were collected using a three-dimensional motion system. Results: The following peak angles were measured: hip flexion, hip adduction (ADD), hip internal rotation (IR), knee flexion, knee abduction (ABD), knee IR, ankle dorsiflexion, ankle inversion, and ankle ADD. No significant differences were observed in the peak angle of each joint across conditions (hip flexion, F(3,39) = 0.85, p = 0.47; hip ADD, F(1.729,22.478) = 1.90, p = 0.18; hip IR, F(1.632,21.220) = 0.67, p = 0.49; knee flexion, F(3,39) = 1.24, p = 0.15; knee ABD, F(1.691,21.982) = 1.24, p = 0.30; knee IR, F(1.830,23.794) = 0.44, p = 0.63; ankle dorsiflexion, F(3,39) = 0.66, p = 0.58; ankle inversion, F(1.385,18.007) = 0.85, p = 0.40; ankle ADD, F(1.865,24.249) = 2.23, p = 0.13). Conclusion: The application of different taping techniques did not significantly change the peak joint angles of the lower extremities during a stop-jump task. These results contradict those of previous studies, suggesting that ankle taping restricts joint range of motion.

Different squatting positions after total knee arthroplasty: a video-based observational study

2020 ◽  
Author(s):  
Jing-yang Sun ◽  
Guo-qiang Zhang ◽  
Tie-jian Li ◽  
Jun-min Shen ◽  
Yin-qiao Du ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Knee Flexion ◽  
Ankle Dorsiflexion ◽  
Flexion Angle ◽  
Knee Flexion Angle ◽  
Total Knee ◽  
The Mean ◽  
Hip Flexion ◽  
Deep Squat

Abstract Aims There are no methods to assess patient’s squatting ability after TKA (total knee arthroplasty), this study aimed to evaluate the different squatting position of a series of patients who underwent primary TKA.Methods From May 2018 to October 2019, we retrospectively reviewed 154 videos recording the squattin-related motions of patients after TKA. Among the included patients, 119 were women and 35 were men. Their mean age at the index surgery was 61.4 years (range, 30 to 77). The median follow-up was 12 months (range, 6 to 156). We classified those squatting-related motions into three major variations according to squatting depth: half squat, parallel squat, and deep squat. The angle of hip flexion, knee flexion and ankle dorsiflexion were measured in the screenshots captured from the videos at the moment of squatting nadir.Results A total of 26 patients were classified as half squat, 75 as parallel squat, and 53 as deep squat. The angle of hip flexion, knee flexion and ankle dorsiflexion all differed significantly among the three squatting positions (p<0.001). In the parallel squat group, the mean knee flexion angle(°) was 116.5 (SD, 8.1; range, 97 to 137). In the deep squat group, the mean knee flexion angle(°) was 132.5 (SD, 9.3; range, 116 to 158). Among the three squatting positions, deep squat showed the highest hip, knee and ankle flexion angle. And the next was parallel squat.Conclusion Our squatting position classification offers a pragmatic approach to evaluating patient’s squatting ability after TKA. However, the relation between squatting position and daily activity requires further investigation.

scholarly journals Instruction and Jump-Landing Kinematics in College-Aged Female Athletes Over Time

2013 ◽  
Vol 48 (2) ◽  
pp. 161-171 ◽  
Author(s):  
Jena Etnoyer ◽  
Nelson Cortes ◽  
Stacie I. Ringleb ◽  
Bonnie L. Van Lunen ◽  
James A. Onate
Keyword(s):  
Lower Extremity ◽  
Retention Test ◽  
Knee Flexion ◽  
Female Athletes ◽  
Initial Contact ◽  
Knee Valgus ◽  
Drop Jump ◽  
Jump Landing ◽  
Peak Knee ◽  
Hip Flexion

Context: Instruction can be used to alter the biomechanical movement patterns associated with anterior cruciate ligament (ACL) injuries. Objective: To determine the effects of instruction through combination (self and expert) feedback or self-feedback on lower extremity kinematics during the box–drop-jump task, running–stop-jump task, and sidestep-cutting maneuver over time in college-aged female athletes. Design: Randomized controlled clinical trial. Setting: Laboratory. Patients or Other Participants: Forty-three physically active women (age = 21.47 ± 1.55 years, height = 1.65 ± 0.08 m, mass = 63.78 ± 12.00 kg) with no history of ACL or lower extremity injuries or surgery in the 2 months before the study were assigned randomly to 3 groups: self-feedback (SE), combination feedback (CB), or control (CT). Intervention(s): Participants performed a box–drop-jump task for the pretest and then received feedback about their landing mechanics. After the intervention, they performed an immediate posttest of the box–drop-jump task and a running–stop-jump transfer test. Participants returned 1 month later for a retention test of each task and a sidestep-cutting maneuver. Kinematic data were collected with an 8-camera system sampled at 500 Hz. Main Outcome Measure(s): The independent variables were feedback group (3), test time (3), and task (3). The dependent variables were knee- and hip-flexion, knee-valgus, and hip- abduction kinematics at initial contact and at peak knee flexion. Results: For the box–drop-jump task, knee- and hip-flexion angles at initial contact were greater at the posttest than at the retention test (P &lt; .001). At peak knee flexion, hip flexion was greater at the posttest than at the pretest (P = .003) and was greater at the retention test than at the pretest (P = .04); knee valgus was greater at the retention test than at the pretest (P = .03) and posttest (P = .02). Peak knee flexion was greater for the CB than the SE group (P = .03) during the box–drop-jump task at posttest. For the running–stop-jump task at the posttest, the CB group had greater peak knee flexion than the SE and CT (P ≤ .05). Conclusions: Our results suggest that feedback involving a combination of self-feedback and expert video feedback with oral instruction effectively improved lower extremity kinematics during jump-landing tasks.

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