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Effect of Selected Exercise Variables on Ligament Stability and Flexibility of the Knee
Abstract
The purpose of the study was to explore the effects of selected combinations of rate of movement, resistance, and two variations of the deep knee squat on collateral ligament stretch in the knee joint, quadriceps muscle strength measured at two leg extension angles, and knee joint flexibility. Sixty-nine male, volunteer, Caucasian students provided the data, and the total experiment was 10 weeks in duration — one week each for pre- and post-testing and 8 weeks for experimental exercises. The main hypotheses were tested in null form and involved the nesting of selected treatment cells into planned contrasts. Multivariate analysis of covariance failed to reject the null hypotheses at the .05 level. Selected variations of the deep squat and half-squat exercises did not produce significant differences in their effect on collateral ligament stretch, quadriceps muscle strength, or knee joint flexibility.
... No decurso do agachamento; a flexão excêntrica envolve uma rotação interna da tíbia e externa do fêmur; na extensão concêntrica, rotação externa da tíbia e interna do fêmur, esse mecanismo assegura a integridade do joelho. Os ligamentos colaterais e parcialmente os ligamentos cruzados atuam na estabilização mediolateral do joelho (2,32). Meyerset al. (32) recrutaram sessenta e nove voluntários para realizar o agachamento parcial e total durante 10 semanas de experimento. ...
... Os ligamentos colaterais e parcialmente os ligamentos cruzados atuam na estabilização mediolateral do joelho (2,32). Meyerset al. (32) recrutaram sessenta e nove voluntários para realizar o agachamento parcial e total durante 10 semanas de experimento. Todos os grupos tiveram diminuição da flexibilidade de ligamento colateral lateral, porém nenhuma constatação de diminuição de flexibilidade e instabilidade mediolateral do joelho foi evidenciada. ...
The squat exercise is widely used to many rehabilitation and strength programs, due
his functional movement in sports performance such as running and jumping and
daily activities. Therefore several articles measure the load in joints of lower
extremity in many conditions. The aim of this papper was to review a series of
articles published between the year of 1971 to 2013, that analyse joint load in the
squat exercise was measured and discussed. In this manner, several pappers agree
that the squat recommendations, with properly execution will be a safe and well
prescribed exercise in rehabilitation and strength programs; however poor technique,
and excess of load, may cause several problems in soft tissues on individuals such
as osteoarthritis. Understanding the biomechanics of the squat such as joint load will
clarify some of applications for physiotherapists, physical educator and clinicians.
... Studies have been made of the mobilising effects of some of these methods, e.g. stretching exercises (Weber and Kraus, 1949;Fieldman, 1966), weight training exercises (Massey and Chaudet, 1956;Meyers, 1971), Hatha Yoga (de Vries, 1962), the exercise effects of sports participation (Skvartsov and Sermeev, 1964), exercises following the principles of proprioceptive neuromuscular facilitation (Tanigawa, 1972), relaxation exercises (Warden, 1961), vibration (Bierman, 1960), massage (Kos, 1966) and heat treatment (Kos, 1966;Grobacker and Stull, 1975). ...
... It is not easy to support the first three alternatives. Meyers (1971) was unable to produce changes in ligament lengths even with heavy weight-assisted stretching exercises continued over a ten week period so it is unlikely that less strenuous exercises performed on only one occasion would do more. The joint capsule and joint ligaments cannot be held to have been subjected to any real stretch in the exercise programme administered. ...
It has been shown that fifteen minutes of locally applied cycloid vibration of low amplitude and frequency is equally as effective as a fifteen minute programme of flexibility exercises in increasing short term mobility of the hip flexors. It is suggested that this mobility change may occur as a result of improved muscle relaxation.
... This is important because excessive anteroposterior or mediolateral knee translation measurements may indicate knee instability due to damage to the cruciate or collateral ligaments. To date, there are seven known studies that examined how the dynamic squat affects anteroposterior or mediolateral knee stability (5,10,21,28,37,49,57). Klein (28) examined how the "deep" squat exercise affected anteroposterior and mediolateral knee stability. ...
... Meyers (37) reproduced the deep squat study by Klein (28), using the same mediolateral collateral ligament testing instrument to measure collateral ligament stability. Sixtynine male subjects were randomly assigned to eight different treatment groups involving variations of the deep and parallel squat consisting of low and high lifting loads and speeds. ...
Because a strong and stable knee is paramount to an athlete's or patient's success, an understanding of knee biomechanics while performing the squat is helpful to therapists, trainers, sports medicine physicians, researchers, coaches, and athletes who are interested in closed kinetic chain exercises, knee rehabilitation, and training for sport. The purpose of this review was to examine knee biomechanics during the dynamic squat exercise.
Tibiofemoral shear and compressive forces, patellofemoral compressive force, knee muscle activity, and knee stability were reviewed and discussed relative to athletic performance, injury potential, and rehabilitation.
Low to moderate posterior shear forces, restrained primarily by the posterior cruciate ligament (PCL), were generated throughout the squat for all knee flexion angles. Low anterior shear forces, restrained primarily by the anterior cruciate ligament (ACL), were generated between 0 and 60 degrees knee flexion. Patellofemoral compressive forces and tibiofemoral compressive and shear forces progressively increased as the knees flexed and decreased as the knees extended, reaching peak values near maximum knee flexion. Hence, training the squat in the functional range between 0 and 50 degrees knee flexion may be appropriate for many knee rehabilitation patients, because knee forces were minimum in the functional range. Quadriceps, hamstrings, and gastrocnemius activity generally increased as knee flexion increased, which supports athletes with healthy knees performing the parallel squat (thighs parallel to ground at maximum knee flexion) between 0 and 100 degrees knee flexion. Furthermore, it was demonstrated that the parallel squat was not injurious to the healthy knee.
The squat was shown to be an effective exercise to employ during cruciate ligament or patellofemoral rehabilitation. For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat. The squat does not compromise knee stability, and can enhance stability if performed correctly. Finally, the squat can be effective in developing hip, knee, and ankle musculature, because moderate to high quadriceps, hamstrings, and gastrocnemius activity were produced during the squat.
... Entretanto, há quem defenda fielmente a idéia de que ele possa ser tranquilamente aplicado desde que respeitando a especificidade de cada um e ainda sugerem que este exercício seria mais seguro do que a caminhada, considerando a tensão produzida no joelho (ESCAMILLA, 2001). Foi também verificado em outros estudos que a aplicação agachamentos profundos e paralelos não afetaria a estabilidade do joelho devido a ação dos músculos posteriores da coxa (MEYERS, 1971;CHANDLER, 1989). ...
A natação, como atividade motora, tem sido praticada pela população mundial a muito tempo, como forma recreativa, lazer, bem como competitiva. Na literatura a ênfase está relacionada ao domínio da aptidão física quando comparado a aptidão motora. No tocante à aptidão motora, os ajustes relacionados aos movimentos são bem descritos na literatura e, em síntese, pode-se observar que há indicadores que são determinantes no desempenho, como no caso da coordenação motora. Na natação, a coordenação motora pode ser definida pelo aproveitamento das fases propulsivas (dentro da água) quando comprada as fases não propulsivas (fora da água) pelo nadador e compreendida a partir de sus estrutura coordenativa. Sendo assim, o objetivo foi observar e compreender como o papel da restrição na habilidade nadar (Oclusão dos óculos parcial – feedback visual) pode influenciar os aspectos variantes e invariantes do nado crawl.
... Entretanto, há quem defenda fielmente a idéia de que ele possa ser tranquilamente aplicado desde que respeitando a especificidade de cada um e ainda sugerem que este exercício seria mais seguro do que a caminhada, considerando a tensão produzida no joelho (ESCAMILLA, 2001). Foi também verificado em outros estudos que a aplicação agachamentos profundos e paralelos não afetaria a estabilidade do joelho devido a ação dos músculos posteriores da coxa (MEYERS, 1971;CHANDLER, 1989). ...
Esta pesquisa consiste numa revisão sistemática. A revisão sistemática teve como objetivo verificar e compreender as motivações à docência e as necessidades de formação na área da saúde, bem como as implicações da autoeficácia na docência no ensino superior no campo da saúde. Para isso, foi realizado um levantamento de publicações na área nos últimos cinco anos. Os resultados encontrados sugerem uma forte relação da autoeficácia docente com a qualidade do ensino
... Aynı çalışmalar yine aynı konularda (Bukh, 1928;Cureton b, 1945Holt, 1978;Holt, Travis ve Okita 1970;Mayers, 1971) yapılmış ve benzer sonuçlar elde edilmiştir. ...
... Training interventions of 8-to 21-weeks duration confirm that parallel [108] and deep back squats [109,110] do not cause any negative effects on knee ligament stability. Measurements of knee stability followed immediately by the execution of parallel back squats with 1.6-fold bodyweight show no significant changes (powerlifters, n = 24) when compared with 19 % (p B 0.01) after a 6.2-mile road race (distance runners, n = 12) or 19 % (p B 0.01) after basketball training (basketball players, n = 10) [111]. ...
In the science and practice of strength training it is sometimes suggested that the deep squat entails an increased injury risk of the lumbar spine and the knee joint. Avoiding deep flexion is believed to minimize the magnitude of knee joint forces. Because within the first 50° of knee flexion calculated retropatellar compressive stress is lower, execution of quarter or half squats is recommended when overuse injuries and degenerative changes of the patella-tendon-complex exist. This recommendation is based on calculation of knee joint forces that occured during the execution of half- and deep-back squats. These values cannot be extrapolated to quarter squats because the following were not taken into account a) the influence of reversal of motion with minor retropatellar contact-zone and lower or missing tendofemoral support-surface and b) the different weights that can be tolerated with the particular squat. This misconception is particularly important when making recommendations for elite training: Due to the advantageous positions of the lever arms at the knee- and hip joints, quarter (and half) squats necessitate higher weights to induce effective training stimuli of the hip and leg extensors compared with deep squats. Accordingly this results in increased knee joint forces and requires a greater degree of torso stabilization to counteract impairing discal shear forces. These relationships were ignored in recent publications so far that have discussed spinal- and knee-joint forces at different squatting depths. Provided that the movement pattern is learned correctly under supervision of a qualified trainer and weights are gradually increased, the deep squat presents an effective training exercise for protection against injuries, particular in junior athlete development. Contrary to commonly voiced concerns, deep squats do not entail increased risks of injury of the passive tissues.
... Training interventions of 8-to 21-weeks duration confirm that parallel [108] and deep back squats [109,110] do not cause any negative effects on knee ligament stability. Measurements of knee stability followed immediately by the execution of parallel back squats with 1.6-fold bodyweight show no significant changes (powerlifters, n = 24) when compared with 19 % (p B 0.01) after a 6.2-mile road race (distance runners, n = 12) or 19 % (p B 0.01) after basketball training (basketball players, n = 10) [111]. ...
It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between March 2011 and January 2013 using PubMed. Over 164 articles were included in the review. There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces. Additionally, with further flexion of the knee joint a cranial displacement of facet contact areas with continuous enlargement of the retropatellar articulating surface occurs. Both lead to lower retropatellar compressive stresses. Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues.
... Trainingsinterventionen mit einer Dauer von acht bis 21 Wochen belegen, dass die parallele (Meyers, 1971) und tiefe Nackenkniebeuge (Chandler et al., 1989, Panariello et al., 1994 keine negativen Auswirkungen auf die Knieligamentstabilität haben. Steiner et al. (1986) diagnostizierten in Messungen der Kniestabilität im unmittelbaren Anschluss nach Ausführung der parallelen Nackenkniebeuge mit dem 1,6-Fachen des KG keine akute signifikante Veränderung im Vergleich zu Messungen nach einem 90-minütigen Basketballtraining (19%, p < 0,01) sowie nach einem 10-km-Strassenlauf (19%, p < 0,01). ...
In Wissenschaft und Praxis des Krafttrainings wird mitunter angenommen, dass die tiefe Kniebeuge eine erhöhte Verletzungsgefahr der Lendenwirbelsäule und des Kniegelenks aufweist. Ein Verzicht auf tiefe Gelenkpositionen soll das Ausmass der Kniegelenkskräfte minimieren. Entsprechend wird bei Überlastungsbeschwerden und degenerativen Veränderungen des Patella-Sehnen-Komplexes die Durchführung der viertel oder halben Kniebeuge empfohlen, da innerhalb der ersten 50° Kniebeugung die geringsten retropatellaren Druckbeanspruchungen berechnet wurden. Diese Empfehlung basiert auf Kalkulationen von Kniegelenkskräften, die bei Ausführung der tiefen und halben Nackenkniebeuge auftraten. Diese Werte können jedoch nicht auf die viertel Kniebeuge übertragen werden, da hierbei a) der Einfluss der Bewegungsumkehr bei geringerer retropatellarer Kontaktzone und geringerer oder fehlender tendofemoraler Unterstützungsfläche und b) die unterschiedlichen Lasthöhen der jeweiligen Kniebeugevariante unberücksichtigt blieben. Dies ist insbesondere im Leistungssport von trainingspraktischer Relevanz: Aufgrund der günstigeren Hebelverhältnisse in Knie- und Hüftgelenken sind in der viertel (und halben) Kniebeuge höhere Lasten als in der tiefen Kniebeuge erforderlich, um Trainingsreize der Hüft- und Beinextensoren zu applizieren. Dies resultiert in einer entsprechenden Zunahme der Kniegelenkskräfte und erfordert eine grössere Stabilisierungsarbeit im Rumpf, um schädigenden discalen Scherkräften entgegenzuwirken. Diese Zusammenhänge blieben in renommierten Publikationen bisher unberücksichtigt, in denen die Kniegelenk- und Wirbelsäulenbelastung in unterschiedlichen Kniebeugetiefen diskutiert wurde.
Vorausgesetzt, dass unter professioneller Trainerbetreuung die Bewegungstechnik korrekt erlernt und die Belastung allmählich gesteigert wird, stellt die tiefe Kniebeuge eine effektive verletzungsprotektive Trainingsmassnahme auch im Nachwuchsbereich dar und birgt, entgegen der landläufigen Meinung, keine erhöhten Verletzungsrisiken des passiven Bewegungsapparates.
... In deep squats, neither anterior nor posterior shear forces may be expected to reach magnitudes, which can harm an intact anterior or posterior cruciate ligament (28,87). Training studies with a duration of 8-21 weeks confirm that parallel (71) and deep back squats (18,77) do not have any negative effects on knee ligament stability. Measurements of knee stability followed immediately by the execution of parallel back squats with 1.6 times bodyweight demonstrate no acute changes (91). ...
Es existieren keine Vergleichsstudien über die Auswirkungen eines periodisierten Maximalkrafttrainings in unterschiedlichen Kniebeugevarianten auf das Einer-Wiederholungsmaximum und das isometrische Explosiv- und Maximalkraftvermögen im 120 Grad Kniegelenkwinkel. Ziel war es, im Rahmen von zehnwöchigen Längsschnittstudien mit 23 weiblichen und 36 männlichen Sportstudierenden (24,11 ± 2,88 Jahre) herauszufinden, ob durch eine Steigerung der dynamischen Maximalkraft in der Viertel-Nackenkniebeuge (120 Grad Kniegelenkwinkel) größere Zugewinne der isometrischen Explosiv- und Maximalkraft in Form eines winkelspezifischen Transfereffektes zu erzielen sind als durch erworbene Maximalkraftzunahmen in der tiefen Front- und Nackenkniebeuge. Die beiden Forschungsprojekte führten zu folgenden, für die Sportpraxis relevanten Erkenntnissen:
1. Ein Krafttraining in der Viertel-Nackenkniebeuge hat hochsignifikante Übertragungsverluste auf das isometrische Explosiv- und Maximalkraftvermögen im 120-Grad-Kniegelenkwinkel zur Folge, was die in der Trainingspraxis angenommene Grundidee von überlegenen winkelspezifischen Transfereffekten widerlegt.
2. Zur effektiven Steigerung der dynamischen Maximalkraft der unteren Extremität ist die Durchführung der tiefen Front- oder Nackenkniebeuge erforderlich, da die tieferen Beugepositionen intensivere Spannungsreize für die Hüft- und Beinextensoren bieten als die geringe Bewegungsamplitude der Viertel-Kniebeuge.
Gefördert durch das Bundesinstitut für Sportwissenschaft (BISp). Aktenzeichen der Forschungsprojekte des BISp: AZ 070509/2007 und AZ 070510/2008
... In deep squats, neither anterior nor posterior shear forces may be expected to reach magnitudes, which can harm an intact anterior or posterior cruciate ligament (28,87). Training studies with a duration of 8-21 weeks confirm that parallel (71) and deep back squats (18,77) do not have any negative effects on knee ligament stability. Measurements of knee stability followed immediately by the execution of parallel back squats with 1.6 times bodyweight demonstrate no acute changes (91). ...
Es existieren keine Vergleichsstudien über die Entwicklung der Sprungleistung in Squat (SJ) und Countermovement Jump (CMJ) durch unterschiedliche Kniebeugevarianten, die eine Bevorzugung einer bestimmten Beugetiefe rechtfertigen könnten. Aus diesem Grund wurden in zwei Forschungsprojekten an 23 weiblichen und 36 männlichen Sportstudierenden (24,11±2,88 Jahre) die Auswirkungen eines periodisierten Maximalkrafttrainings in der tiefen Frontkniebeuge (Gruppe FKB, n= 20), tiefen Nackenkniebeuge (Gruppe NKB, n= 20) und der viertel Nackenkniebeuge bis 120° Kniegelenkwinkel (Gruppe NKB¼, n= 19) auf die Schnellkraftleistung in SJ und CMJ untersucht. Die Parallelisierung der drei Versuchsgruppen erfolgte auf Basis der Sprunghöhen im CMJ. Zusätzlich wurde eine Kontrollgruppe (K, n= 16) gebildet (Alter: 24,38±0,50 Jahre). Das zehnwöchige periodisierte Krafttraining (2 Tage / Woche) resultierte in signifikanten (p≤0,001) Steigerungen der dynamischen Maximalkraft in der spezifischen Kniebeugevariante der jeweiligen Trainingsgruppe. Gruppe FKB und Gruppe NKB zeigten signifikante und nahezu gleichwertige Zunahmen in den Sprunghöhen von SJ (p≤0,001) und CMJ (p≤0,001), ohne einen Gruppenunterschied zwischen diesen beiden Gruppen aufzuweisen (p= 0.852 und p= 0.626). Für Gruppe NKB¼ und Gruppe K waren keine statistisch signifikanten Veränderungen des Schnellkraftvermögens in SJ und CMJ zu ermitteln. Der Ausgangstest im SJ erbrachte für Gruppe FKB und Gruppe NKB jeweils signifikant höhere Schnellkraftleistungen gegenüber Gruppe K (p= 0,013; p= 0,029). Während in diesem Test für Gruppe NKB kein statistisch bedeutsamer Gruppenunterschied zur Gruppe NKB¼ festzustellen war (p= 0,116), zeigte Gruppe FKB tendenziell höhere Sprungleistungen als Gruppe NKB¼ (p= 0,052). Der Ausgangstest im CMJ war für Gruppe FKB und Gruppe NKB jeweils mit signifikant höheren Sprungleistungen gegenüber Gruppe NKB¼ (p= 0,000) und Gruppe K (p= 0,000) verbunden.
Die Ergebnisse der beiden Forschungsprojekte führten zu folgenden, für die Sportpraxis relevanten, Erkenntnissen:
1) Eine winkelspezifische Zunahme der dynamischen Maximalkraft in der viertel NKB erbringt keine leistungsfördernden Übertragungseffekte auf das Schnellkraftverhalten der Bein- und Hüftextensoren in konzentrischer Arbeitsweise (SJ) und im langen Dehnungsverkürzungs-Zyklus (CMJ).
2) Zur Steigerung des Schnellkraftvermögens in SJ und CMJ sind aus funktioneller Sicht tief durchgeführte Front- und Nackenkniebeugen als effektive Trainingsmaßnahmen zu betrachten, da ausschließlich in tiefen Gelenkpositionen die erforderliche Reizapplikation zur positiven Beeinflussung des Beschleunigungsablaufs gewährleistet wird. Diese Übungen sollten als ein grundlegender Bestandteil des allgemeinen Krafttrainings in Sportarten dienen, in denen ein hohes Schnellkraftvermögen der unteren Extremitäten von entscheidender Bedeutung ist.
Gefördert durch das Bundesinstitut für Sportwissenschaft (BISp). Aktenzeichen der Forschungsprojekte des BISp: AZ 070509/2007 und AZ 070510/2008
... Training interventions of 8-to 21-weeks duration confirm that parallel [108] and deep back squats [109,110] do not cause any negative effects on knee ligament stability. Measurements of knee stability followed immediately by the execution of parallel back squats with 1.6-fold bodyweight show no significant changes (powerlifters, n = 24) when compared with 19 % (p B 0.01) after a 6.2-mile road race (distance runners, n = 12) or 19 % (p B 0.01) after basketball training (basketball players, n = 10) [111]. ...
It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between March 2011 and January 2013 using PubMed. Over 164 articles were included in the review. There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces. Additionally, with further flexion of the knee joint a cranial displacement of facet contact areas with continuous enlargement of the retropatellar articulating surface occurs. Both lead to lower retropatellar compressive stresses. Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues.
... In deep squats, neither anterior nor posterior shear forces may be expected to reach magnitudes, which can harm an intact anterior or posterior cruciate ligament (28,87). Training studies with a duration of 8-21 weeks confirm that parallel (71) and deep back squats (18,77) do not have any negative effects on knee ligament stability. Measurements of knee stability followed immediately by the execution of parallel back squats with 1.6 times bodyweight demonstrate no acute changes (91). ...
It is unclear if increases in one repetition maximum (1-RM) in quarter squats result in higher gains compared to full depth squats in isometric force production and vertical jump performance. The aim of the research projects was to compare the effects of different squat variants on the development of 1-RM and their transfer effects to Countermovement (CMJ) and Squat Jump (SJ) height, maximal voluntary contraction (MVC) and maximal rate of force development (MRFD). Twenty-three women and 36 men (mean age: 24.11±2.88) were parallelized into three groups based on their CMJ height: deep front squats (FSQ, n=20), deep back squats (BSQ, n=20) and quarter back squats (BSQ¼, n=19). In addition a control group (C, n=16) existed (mean age: 24.38±0.50). Experimental groups trained 2 d·wk for 10 weeks following a strength-power periodization, which produced significant (p≤0.05) gains of the specific squat 1-RM. FSQ and BSQ attained significant (p≤0.05) elevations in SJ and CMJ without any interaction effects between both groups (p≥0.05). BSQ¼ and C did not reveal any significant changes of SJ and CMJ. FSQ and BSQ had significantly higher SJ scores over C (p≤0.05). BSQ did not feature any significant group difference to BSQ¼ (p=0.116) in SJ, whereas FSQ showed a trend towards higher SJ heights over BSQ¼ (p=0.052). FSQ and BSQ presented significantly (p≤0.05) higher CMJ heights over BSQ¼ and C. Post-test in MVC and MRFD demonstrated no significant changes for BSQ. Significant declines in MRFD for FSQ in the right leg (p≤0.05) without any interaction effects for MVC and MRFD between both FSQ and BSQ were found. Training of BSQ¼ resulted in significantly (p≤0.05) lower RFD and MVC values in contrast to FSQ and BSQ. Quarter squat training elicited significant (p≤0.05) transfer losses into the isometric maximal and explosive strength behavior. Our findings therefor contest the concept of superior angle specific transfer effects. Deep front and back squats guarantee performance-enhancing transfer effects of dynamic maximal strength to dynamic speed-strength capacity of hip and knee extensors compared to quarter squats.
The development of optimal strength potential in American female athletes has been neglected. This study documents the response of 13 men and 13 women of college age to an intensive power lifting program designed to duplicate a program followed by competitive male lifters. The results identified two significant training concepts: (1) the full squat must be considered the cornerstone exercise, because it quickly stimulates overall strength increases in both men and women, and (2) the women had the same physiological ability as men to tolerate and adapt to the demanding physical stress of power lifting.
THERE IS A GREAT DEAL OF DEBATE AMONG STRENGTH AND CONDITIONING PROFESSIONALS, REHABILITATION SPECIALISTS, AND RESEARCHERS REGARDING THE SAFETY AND EFFICACY OF PERFORMING THE DEEP SQUAT EXERCISE. IN THIS ARTICLE, THE POTENTIAL BENEFITS AND THE POTENTIAL RISKS OF PERFORMING THIS CLOSED-KINETIC CHAIN LOWER EXTREMITY EXERCISE WILL BE DISCUSSED. WE WANT TO HEAR FROM YOU. VISIT NSCA-SCJ.com TO WEIGH IN ON THE POINT/COUNTERPOINT QUICK POLL.
A#$ to the grass. Below parallel. Hamstrings resting on calves. All synonymous with deep squatting. A study performed by Caterisano et al 2002 provides valuable insight into squat depth and muscle activation. In this study, the researchers found glute activation during full squats to be greater than twice that of partial squats (35.4% compared to 16.9%), hamstring activation to be similar, while quadriceps activation dominated during the partial squats only. Understanding that the glutes and hamstrings (and to some extent the adductors) are the primary hip extensors during sprinting/accelerating, the take home message from this and other studies (Robertson et al 2008), could completely change the way athletes prepare for and perform on the field.. From his book Strong Enough, Dr. Mark Rippetoe states the fundamental misunderstanding here is about what were trying to accomplish when we squat. The quadriceps are not the only muscles that are supposed to be involved in the exercise. The hamstring muscles on the back of the thigh attach at the front of the tibia, at the bottom of the knee, wrap around it on both sides and pull back on the knee from below it as they get tight. The adductors connect the groin area of the pelvis to the medial (inside) aspect of the femur, and these muscles also pull back on the knee when they tighten, but from above the knee and toward the inside. Both of these muscle groups tighten from behind the knee as the torso leans forward, the knees travel out to stay parallel to the feet, and the hips reach back of correct depth, balancing the forward pulling stress from the quadriceps and the patellar tendon around the front of the knee. But they only exert this balancing pull when they are stretched, in the full squat position (6).
Abstract The barbell back squat is commonly used by athletes participating in resistance training. The barbell squat is typically performed using standard athletic shoes, or specially designed weightlifting footwear, although there are now a large number of athletes who prefer to squat barefoot or in barefoot-inspired footwear. This study aimed to determine how these footwear influence 3-D kinematics and muscle activation potentials during the barbell back squat. Fourteen experienced male participants completed squats at 70% 1 rep max in each footwear condition. 3-D kinematics from the torso, hip, knee and ankle were measured using an eight-camera motion analysis system. In addition, electromyographical (EMG) measurements were obtained from the rectus femoris, tibialis anterior, gastrocnemius, erector spinae and biceps femoris muscles. EMG parameters and joint kinematics were compared between footwear using repeated-measures analyses of variance. Participants were also asked to subjectively rate which footwear they preferred when performing their squat lifts; this was examined a chi-squared test. The kinematic analysis indicated that, in comparison to barefoot the running shoe was associated with increased squat depth, knee flexion and rectus femoris activation. The chi-squared test was significant and showed that participants preferred to squat barefoot. This study supports anecdotal evidence of athletes who prefer to train barefoot or in barefoot-inspired footwear although no biomechanical evidence was found to support this notion.
ABSTRACT: The purpose of this study was to analyze the differences in tibiofemoral joint mechanics between males and females during squatting using the Trapezoid bar (TB) and Straight bar (SB). Twenty-two subjects were recruited from the University of Florida. Each subject performed two randomly assigned squat tests, one using a straight bar and the other using a trapezoid bar. Each test consisted of two trials with each trial consisting of three repetitions. Video, force platform and EMG were used to collect kinetic, kinematic and muscle activity data. MANOVA results for the EMG data found significant differences for Quadriceps activity between the TB and SB squat conditions with the TB resulting in higher quadriceps muscle activation. Significant differences were also found between the ascending and descending phases of the squat for gluteal and hamstring muscle activity. The ascending phase resulted in higher muscle activation than the descending phase. The MANOVA also revealed significant interactions between phase and gender for gluteal and hamstring muscle activity as well as significant interactions between phase and bar type for quadriceps muscle activity. An ANOVA revealed significant differences between bar types for compressive force, anteriorly directed shear force and extension moment at the tibiofemoral joint with the TB squat resulting in the higher values for compressive force, shear force and extension torque. T-tests were performed to determine differences in normalized hip width, Q-angle, and maximum knee angle during each SB and TB squat trial. There were significant differences detected for all of these measures. Women had a larger Q-angle and normalized hip width as compared to the males of this study. There were no differences between maximum knee angle during the TB and SB squats. This study identified differences between phases and bar types for knee joint mechanics and muscle activity. Despite significant differences between genders for normalized hip width and Q-angle there was no observable difference between males and females of this study for joint kinetics, joint kinematics or muscle activation. This suggests that Q-angle and hip width do not have an effect on tibiofemoral joint kinetics or lower extremity muscle activity during squatting which may be as a result of the non-ballistic nature or the squat. Text (Electronic thesis) in PDF format. System requirements: World Wide Web browser and PDF reader. Mode of access: World Wide Web. Title from title page of source document. Document formatted into pages; contains 90 pages. Thesis (M.S.)--University of Florida, 2005. Includes vita. Includes bibliographical references.
Past studies have produced conflicting results as to the effect of squat exercises on knee stability. One hundred male and female college students were measured using a knee ligament arthrometer on nine tests of knee stability. Over an 8-wk training program, full or half squats did not consistently affect knee stability compared to non-squatting controls. To measure the effect of long-term squat training 27 male powerlifters (14 Elite or Master Class) and 28 male weightlifters (8 Elite or Master Class) were measured on the same tests. Powerlifters were significantly tighter than controls on the anterior drawer at 90 degrees of knee flexion. Both powerlifters and weightlifters were significantly tighter than controls on the quadriceps active drawer at 90 degrees of knee flexion. Data on powerlifters and weightlifters were also analyzed by years of experience and skill level. No effect of squat training on knee stability was demonstrated in any of the groups tested.
Although the squat exercise is considered essential for optimal athletic performance, controversy exists re garding the effect on knee stability. The purpose of this prospective study was to determine the effect of squat exercises on in vivo knee joint stability of professional football players. Thirty-two subjects with normal knees participated in a 21-week off-season training program. Subjects performed power squat exercises with barbell loads of 130% to 200% body weight twice weekly. Both knees of each subject were tested by a single examiner with a knee ligament arthrometer before the training program and at 12 and 21 weeks. Passive displace ments were recorded at 67, 89, and 133 N with the knee at 30° and 90° of flexion. Active testing was performed with the knee in the same positions. Student's paired t-tests were used to compare pre- and postexercise measures. For all subjects, no significant differences were found between pre- and postexercise results for active and passive tests. Of the 2440 measurements taken, only 8 demonstrated increased excursions greater than 2 mm.
This study demonstrates no significant increases in anterior-posterior tibiofemoral translation in athletes using the squat exercise as part of their off-season training program.
To our knowledge, no scientific literature has examined the 3-dimensional forces acting at the knee joint during a power clean. Ten male weightlifting subjects (25.9 years, SD 3.54) performed 1 set of the power clean at 60 and 70% of their maximal collegiate level for 5 repetitions. The subjects displayed a large compressive, moderate anterior, and a small degree of lateral and medial force at the knee during both percentage lifts. The majority of these forces occurred during the second pull phase or the catching phase of the lift. Lifters with decreased weight/system weight percentages displayed a more efficient lift that placed less stress on the knees. This analysis may provide invaluable information in the assessment of weight percentages used for Olympic weightlifters throughout the training year. the power clean.
This study was to determine the relative effects of varying degrees of mobilization on the ligaments of the knee, with particular reference to resistance to tearing under imposed stress. Four groups of female white rats of the Wistar strain of experimental stock were subjected to varying degrees of mobilization. One group was confined in small, individual cubicles that restricted opportunities for movement. One group was allowed to roam at will in a large pen. The third group was exercised for 15 min. a day, 5 times a week, for a 5-week period, in a rotating exercise drum. The fourth group was similarly exercised in a drum with an uneven surface. Results showed that there was a direct relationship between ligament strength, as measured in this experiment, and the degree of mobilization of the knee joint evidenced in the four exercise programs.
Data have been presented relative to the strength and force-elongation relationships of rat ligaments. The findings indicated that the testing methods employed are sufficiently reliable for experimental purposes. Results showed that body weight, sex, and age of the animals are important parameters when evaluating separation force results. Absence of adrenal or thyroid glands had no significant influence on the strength of the medial collateral ligament. It was concluded that the strength of the medial collateral ligament was dependent upon its osseous attachment.
Force-elongation data suggested that ligamentous strength and elongation are independent properties. Ligaments from adrenalectomized and thyroidectomized rats exhibited significantly more elongation than ligaments from normal rats. The responsible mechanisms are unknown and are the focus for current studies.
The purpose of this study was to determine whether a flexibility training program, a weight training program, and the combination of both would affect running speed when used as supplementary training programs to the conventional method of training sprinters. One hundred and forty-five subjects, randomly assigned to one of five training groups, were tested for flexibility, leg strength, and running speed before and after an 8-week training period. Results showed that both weight training and flexibility training, as supplements to sprint training, increased running speed significantly more than an unsupplemented sprint training program.
Sixty male albino rats were divided into four groups. The rats in the first group were exercised; those in the second were subjected to intermittent passive stretching of one hind leg; those in the third group had one hind leg immobilized; those in the fourth group served as controls. At the end of 4 weeks, all animals were sacrificed and the muscle tissue was dissected from the hind legs. The limbs were then torn apart at the knee joint. No significant differences were found in the amount of stress required to tear the knee ligaments in the various groups.
Submitted on September 29, 1959
The effect of early and late physical reconditioning following knee surgery
- William M Brenner
- Karl K Klein
BRENNER, WILLIAM M., and KLEIN, KARL K. The effect of early and late physical reconditioning following knee surgery. Journal of the Association for Physical and Mental Rehabilitation 15: 166-69, November-December 1961.
Does weight training belong in the program
- Counsilman
- James
COUNSILMAN, JAMES E. Does weight training belong in the program? Journal of Health, Physical Education, Recreation 26:17-18, January 1955.
Biophysical values of muscular activity: With implications for research
- Elwood C Davis
- Gene A Logan
DAVIS, ELWOOD c., and LoGAN, GENE A. Biophysical values of muscular activity: With implications for research. Dubuque, Iowa: Wm. C. Brown Co., 1961.
A comparison of bilateral quadriceps muscle strength of individuals in good and poor postural balance
- Karl K Klein
KLEIN, KARL K. A comparison of bilateral quadriceps muscle strength of indi-viduals in good and poor postural balance. Physical Educator 11:42-43, May 1954.
Muscular fitness and health
- Hans Kraus
- Ruth Hirschland
KRAUS, HANS, and HIRSCHLAND, RUTH. Muscular fitness and health. Journal of Health, Physical Education, Recreation 24: 17-19, December 1954.
On the significance of flexibility for physical educators. Jour-nal of Health
- Leighton
- Jack
LEIGHTON, JACK R. On the significance of flexibility for physical educators. Jour-nal of Health. Physical Education, Recreation 31 :27-28, November 1960.
Measurement in physical education
- Carlton R Meyers
- Erwin T Blesh
MEYERS, CARLTON R., and BLESH, T. ERWIN. Measurement in physical educa-tion. New York: Ronald Press Co., 1962.
Effects of physical activity upon knee ligament separation force in experimental animals. Paper read before the Research Section of the American Association for Health, Physical Education, and Recreation
- Jerome Zuckerman
ZUCKERMAN, JEROME. Effects of physical activity upon knee ligament separation force ill experimental animals. Paper read before the Research Section of the American Association for Health, Physical Education, and Recreation, Boston, Mass., April 12, 1969. Downloaded by [University of Sussex Library] at 05:17 09 February 2015
- Klein Karl K.
The deep squat exercise as utilized in weight training for athletics and its effect on the ligaments of the knee
- Karl K Klein
- Counsilman James E.
- Kraus Hans
Journal of Health, Physical Education, Recreation
- James E Counsilman
- Leighton Jack R.
The knee and the ligaments
- Karl K Klein
The knees: Growth-development and activity influences
- Karl K Klein
On the significance of flexibility for physical educators
- Jack R Leighton