An Investigation of the Relationship Between Impact Force Attenuation in Landing and Isokinetic Strength of Knee Muscles in Individuals with Different Training Backgrounds PDF Download
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Book Description
Skeletal muscle is a major active mechanism of impact force attenuation in human movement. During the landing phase impact attenuation is achieved through eccentric contraction of the muscles of the lower extremity. However, few studies have investigated the effects of knee strength, especially eccentric strength, on impact attenuation during landing. Therefore the relationship was assessed in fourteen healthy, male volunteers. Seven NCAA Division I College football players (TRAINED) and seven recreationally active university students with limited sport training or competitive sport background (REC) participated in two testing sessions. Isokinetic testing of the knee extensor and flexor muscles was performed concentrically at 60 and 180 degree·sec−1, and eccentrically at 60 degree·sec−1. 3D kinematic and ground reaction force (GRF) data were collected during drop landings from heights of 40, 60cm and 100% of each individuals maximum jump height. The TRAINED had greater concentric strength, vertical jump height, but no significant differences existed in the eccentric strength (336 vs 340 N.m/kg) between the groups. The TRAINED had marginally greater peak GRFs (2.7 & 3.5 BW vs 2.0 & 2.7 BW for 40 and 60 cm, p=0.051) and significantly less time to the peak (0.048 & 0.043 s vs 0.060 & 0.053) compared to the REC in drop landing. The TRAINED used less but non-significant knee flexion range of motion ( -60.7 & -54.1 degree vs -62.7 & -69.6 degree) during drop landing than the REC. There were high, positive and significant correlations between the peak eccentric knee extensor torque and time to the first and second peak GRF. Despite all their training the results did not find any significant differences in eccentric strength of the TRAINED subjects in comparison to their REC counterparts. The TRAINED subjects adopted a stiffer landing strategy to deal effectively with high impact loading during landing. Future research is warranted in investigating impact attenuation in landing of participants with significantly different eccentric strength.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Book Description
Skeletal muscle is a major active mechanism of impact force attenuation in human movement. During the landing phase impact attenuation is achieved through eccentric contraction of the muscles of the lower extremity. However, few studies have investigated the effects of knee strength, especially eccentric strength, on impact attenuation during landing. Therefore the relationship was assessed in fourteen healthy, male volunteers. Seven NCAA Division I College football players (TRAINED) and seven recreationally active university students with limited sport training or competitive sport background (REC) participated in two testing sessions. Isokinetic testing of the knee extensor and flexor muscles was performed concentrically at 60 and 180 degree·sec−1, and eccentrically at 60 degree·sec−1. 3D kinematic and ground reaction force (GRF) data were collected during drop landings from heights of 40, 60cm and 100% of each individuals maximum jump height. The TRAINED had greater concentric strength, vertical jump height, but no significant differences existed in the eccentric strength (336 vs 340 N.m/kg) between the groups. The TRAINED had marginally greater peak GRFs (2.7 & 3.5 BW vs 2.0 & 2.7 BW for 40 and 60 cm, p=0.051) and significantly less time to the peak (0.048 & 0.043 s vs 0.060 & 0.053) compared to the REC in drop landing. The TRAINED used less but non-significant knee flexion range of motion ( -60.7 & -54.1 degree vs -62.7 & -69.6 degree) during drop landing than the REC. There were high, positive and significant correlations between the peak eccentric knee extensor torque and time to the first and second peak GRF. Despite all their training the results did not find any significant differences in eccentric strength of the TRAINED subjects in comparison to their REC counterparts. The TRAINED subjects adopted a stiffer landing strategy to deal effectively with high impact loading during landing. Future research is warranted in investigating impact attenuation in landing of participants with significantly different eccentric strength.
Author: Harry Fisher
Publisher:
ISBN: 9781321890419
Category : Biomechanics
Languages : en
Pages : 49
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Book Description
The current study quantified the relationship between force production during isometric squats performed at different external knee flexion angles (40, 60, 80, and 100 degrees) and initial and peak knee flexion angles during landing. A total of 18 male and 18 female recreational/collegiate athletes completed a jump-landing-jump task and four maximal isometric squats at different knee flexion angles. Significant correlations were observed between peak force production during isometric squats and initial and peak knee flexion angles during landing for females, but not for males. For females, decreased isometric strength during squats was associated with decreased knee flexion during landing. For males, isometric strength alone may not be sufficient to explain differences in knee flexion during landing. Future studies are warranted to study the effect of postural-specific strength training on landing mechanics in females.
Author: Colin Arthur Duffett
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Fatigue is a complex, multifactorial phenomenon that affects the neuromuscular system from the muscle fibers and neuromuscular junction to the higher planning centers in the brain and reflects interactions along the entire system. 'Neuromuscular fatigue' refers to the decrease in physical performance associated with an increase in the real and/or perceived difficulty of a task, regardless if the force or power can be sustained, and is present and progressing from the onset of the task that is reversible with rest. It consists of central and peripheral components such as decreases in central drive (central fatigue) or contractile responses (peripheral fatigue) and is suggested to occur at any site involved in the muscle contraction. Fatigue also has a mental component that describes an emotion suggested to act as a warning sign for maintaining physical integrity. Neuromuscular fatigue may depend on both the muscles employed and on the type of exercise from which fatigue results and are specific to the task and dependent on the mechanisms which are the most stressed during the task. Fatigue can either be localized or global, meaning it can affect the muscles exercised or the entire body system resulting in fatigue effects in non-exercised muscle groups. A growing body of research revolves around the effects of fatiguing exercise and their impact on the performance of non-exercised muscles, termed non-local muscle fatigue (NLMF). The presence of NLMF effects is conflicting, with effects seemingly dependent on many factors such as contraction intensity, fatiguing exercise volume, muscle group fatigued and tested, muscle action, and the detection method(s) used. NLMF research has many implications for rehabilitation and training purposes, as well as widening our understanding of global fatigue mechanisms. A relatively unexplored aspect of NLMF is whether the testing is velocity specific. The purpose of this study was to investigate the effects of fatigue induced by simultaneous low velocity unilateral isokinetic knee extensions and flexions on contralateral knee slow and fast velocity extensor and flexor isokinetic force and electromyography (EMG). In a randomized, repeated measures, crossover design, peak torque, EMG, and rate of perceived exertion measures were measured from the non-dominant vastus lateralis and biceps femoris before and after unilateral fatiguing protocols of the dominant knee extensors and flexors. The fatiguing protocols consisted of 4 sets of 15 maximal isokinetic knee extension and flexion contractions. In addition, a fatigue resistance test was also completed post-intervention. The current study used 16, university-aged (ages 18-30) participants (10 males and 6 females) who were resistance trained. Peak torque of the dominant (exercised) quadriceps and hamstrings decreased when tested at slow and high velocities. Peak torque of the non-dominant quadriceps and hamstrings during post-test (p=0.6 and p=0.3 respectively), or first or last repetition of repetitive fatigue test (p=0.8, p=0.06, and p=0.8, p=1.0, respectively) tested at slow velocity was not significantly different from control, demonstrating a lack of peak torque or fatigue endurance NLMF effects. In addition, there was no relative (normalized) differences in peak torque for velocity specific or fast test velocities. However, the fast velocity repetitive fatigue test resulted in a greater decrease from first to the last repetition than the slow test, as demonstrated by the fatigue index (FI), but was not significantly different from control. This study highlights that prior unilateral fatigue of the dominant quadriceps and hamstrings by repetitive slow maximal isokinetic actions did not demonstrate decreases in singular maximal peak torque or repetitive fatigue endurance in the contralateral muscles. In addition, velocity specific effects were not demonstrated in relative peak torque or relative fatigue endurance changes. There was also no observable effect on the rating of perceived exertion following control vs fatigue (4.6 vs 6.3, p>0.05), or slow vs. fast testing (5.8 vs 6.8, p>0.05) on post-repetitive test values.
Author: Ashraf G. Veldekens
Publisher:
ISBN: 9780591174885
Category :
Languages : en
Pages : 35
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The purpose of this study was to examine the effect of isokinetic eccentric muscle training activities in comparison with isotonic eccentric muscle training activities of the quadriceps muscle for knee extension (torque, work, and power). Forty-five healthy female volunteer subjects between the ages of 22 and 64 were recruited for this training study. the null hypotheses were that there would be no difference between the control, isotonic and isokenetic groups and no difference in the baseline to post training sessions. All subjects had an orthopaedic screening of their lower extremities. In a test/retest experimental design, the right quadriceps muscle groups of each subject was tested in the isokinetic mode with an eccentric/extension contraction. Subjects were divided into three groups--Eccentric Isotonic (ET), Eccentric Isokinetic (EK), and the Control (C). the EK training included 5 eccentric knee extension and flexion contractions on the BioDex Unit at the speeds of 60, 60, 75 and 75 degrees per second. Five repetitions were done with a 10 second rest. the ET group was exercised in the isotonic mode on the BioDex. the ET performed twenty eccentric exercise repetitions at each training session. the resistance load was adjusted for each subject through the training interval to assure isometric maximal quadriceps loading (in extension) for twenty repetitions. Twenty-four training sessions were performed at the same time of day for both groups. the control group was not trained. Subject performance data on peak torgue (PT) and total work (TW) was collected on the computer system using SYSTAT. A two-way ANOVA was used to determine the effect of group on peak torque and total work. Statistically the results showed that no significant differences existed between the isokinetic eccentric and the isotonic eccentric training for knee extension. Power using a vertical jump test after training was not significant either. An ANCOVA analysis was performed with pretraining measurements of torque as the co-variable. Although there were no significant differences from any of the dependent variables, there was a slight trend for improvement in isokinetic eccentric training, primarily in the variable of total work.
Author: Roger Bartlett
Publisher: Routledge
ISBN: 1135818177
Category : Science
Languages : en
Pages : 304
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Book Description
First published in 1996. Routledge is an imprint of Taylor & Francis, an informa company.
Author: Ola Grimsby
Publisher: Lulu.com
ISBN: 0615254519
Category : Science
Languages : en
Pages : 558
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Book Description
This long awaited textbook from The Ola Grimsby Institute provides decades of clinical experience and reasoning, with both historical and current evidence, with rationale for both passive and active treatments in orthopaedic manual therapy. Practical guidelines for joint mobilization and exercise rehabilitation are presented with this logical and exciting work. Incorporating experience and science, this book provides new approaches and treatment principles to make what you already do more effective. Extensive Content: Over 535 pages and 275 illustrations, photographs and tables Ola Grimsby and his co-authors have compiled a significant resource for the practicing physical therapist, manual therapist or osteopath.
Author: Duane Knudson
Publisher: Springer Science & Business Media
ISBN: 1475752989
Category : Medical
Languages : en
Pages : 332
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Book Description
Fundamentals of Biomechanics introduces the exciting world of how human movement is created and how it can be improved. Teachers, coaches and physical therapists all use biomechanics to help people improve movement and decrease the risk of injury. The book presents a comprehensive review of the major concepts of biomechanics and summarizes them in nine principles of biomechanics. Fundamentals of Biomechanics concludes by showing how these principles can be used by movement professionals to improve human movement. Specific case studies are presented in physical education, coaching, strength and conditioning, and sports medicine.
Author: Lior Laver
Publisher: Springer Nature
ISBN: 3662610701
Category : Medical
Languages : en
Pages : 1018
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Book Description
This book is designed as a comprehensive educational resource not only for basketball medical caregivers and scientists but for all basketball personnel. Written by a multidisciplinary team of leading experts in their fields, it provides information and guidance on injury prevention, injury management, and rehabilitation for physicians, physical therapists, athletic trainers, rehabilitation specialists, conditioning trainers, and coaches. All commonly encountered injuries and a variety of situations and scenarios specific to basketball are covered with the aid of more than 200 color photos and illustrations. Basketball Sports Medicine and Science is published in collaboration with ESSKA and will represent a superb, comprehensive educational resource. It is further hoped that the book will serve as a link between the different disciplines and modalities involved in basketball care, creating a common language and improving communication within the team staff and environment.
Author: Iain K. Crombie
Publisher: John Wiley & Sons
ISBN: 1119835240
Category : Medical
Languages : en
Pages : 164
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Book Description
This second edition of the popular guide to critical appraisal is a fully updated revision of the previous edition. Written in the same easily accessible style, The Pocket Guide to Critical Appraisal now provides annotated checklists of the most common research designs. Consistent with recent developments in evidence-based medicine, these checklists distinguish between the risk of bias in the conduct of published studies and the value of the findings for healthcare delivery. Five new chapters have been added and the original chapters have been rewritten, making the new edition a complete and concise guide for the evaluation of research quality. In addition to the checklists, the book also: describes how to quickly identify the information needed for the critical appraisal provides simple explanations of statistical significance and the interpretation of confidence intervals reviews the major sources of bias and their impact on research findings explains how to summarise the risk of bias outlines the concept of certainty of evidence and how to calculate it identifies the challenges in assessing the value of research findings The Pocket Guide to Critical Appraisal is an essential guide for all health professions and students who read research papers and use their findings.
Author: Greenwood Donald T
Publisher:
ISBN: 9780876925386
Category :
Languages : en
Pages : 552
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Book Description
