Neuromuscular Control of the Knee during a Resisted Single-Limb Squat Exercise

Shields, Richard K.; Madhavan, Sangeetha; Gregg, Emy; Leitch, Jennifer; Petersen, B.; Salata, Sara; Wallerich, Stacey

doi:10.1177/0363546504274150

Cited by 71 publications

(78 citation statements)

References 25 publications

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“…However, due to the consistently reported low HS activity during unilateral WB exercises, 5,9,17,24,30 which is consistent with our findings, these exercises would have limited strengthening effects in healthy individuals. If HS strengthening is indicated, exercises such as the HS muscle curl exercise should be considered.…”

Section: Biceps Femorissupporting

confidence: 91%

Electromyographical Analysis of selected Lower Extremity Muscles During 5 Unilateral Weight-Bearing Exercises

Ayotte

Stetts²,

Keenan³

et al. 2007

J Orthop Sports Phys Ther

187

138

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Section: Biceps Femorissupporting

confidence: 91%

Electromyographical Analysis of selected Lower Extremity Muscles During 5 Unilateral Weight-Bearing Exercises

Ayotte

Stetts²,

Keenan³

et al. 2007

J Orthop Sports Phys Ther

187

138

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“…The single-limb squat, [26][27][28][29][30] Participants slowly lowered themselves toward the ground using their ankle, knee, and hip joints until they could touch the contralateral middle finger to the outside of the dominant foot without reaching with their shoulders. Next, they returned to the starting position and were instructed to keep their knees over their toes to prevent a knee valgus position (Figure 1).…”

Section: Methodsmentioning

confidence: 99%

“…[26][27][28][29]31,32 The single-limb squat frequently is used in functional movement screenings designed to identify individuals with faulty neuromechanics and in rehabilitation programs. Beutler et al 29 recommended the use of the single-limb squat exercise for quadriceps strengthening after they observed peak quadriceps activity at 201% MVIC and peak hamstrings activity at 81% MVIC during this exercise.…”

Section: Moderate Coactivation Ratiosmentioning

confidence: 99%

“…However, modifications have been identified for the single-limb squat that can facilitate more balanced coactivation by adding resistance to both the flexion and extension phases. 27 Shields et al 27 discovered that adding resistance to the single-limb squat increased hamstrings (BF) activation by 12% MVIC and improved Q:H ratios from 3.0 to 2.32 at the highest resistance. Whereas the exercise remained quadriceps dominant overall and might not facilitate hamstrings strengthening, increasing the resistance did result in slightly more balanced activation.…”

Section: Moderate Coactivation Ratiosmentioning

confidence: 99%

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Quadriceps and Hamstrings Coactivation During Common Therapeutic Exercises

Begalle

DiStefano

Blackburn

et al. 2012

Journal of Athletic Training

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Context: Anterior tibial shear force and knee valgus moment increase anterior cruciate ligament (ACL) loading. Muscle coactivation of the quadriceps and hamstrings influences anterior tibial shear force and knee valgus moment, thus potentially influencing ACL loading and injury risk. Therefore, identifying exercises that facilitate balanced activation of the quadriceps and hamstrings might be beneficial in ACL injury rehabilitation and prevention.Objective: To quantify and compare quadriceps with hamstrings coactivation electromyographic (EMG) ratios during commonly used closed kinetic chain exercises.Design: Cross-sectional study. Setting: Research laboratory.Patients or Other Participants: Twenty-seven healthy, physically active volunteers (12 men, 15 women; age ¼ 22.1 6 3.1 years, height ¼ 171.4 6 10 cm, mass ¼ 72.4 6 16.7 kg).Intervention(s): Participants completed 9 separate closed chain therapeutic exercises in a randomized order.Main Outcome Measure(s): Surface electromyography quantified the activity level of the vastus medialis (VM), vastus lateralis (VL), medial hamstrings (MH), and biceps femoris (BF) muscles. The quadriceps-to-hamstrings (Q:H) coactivation ratio was computed as the sum of average quadriceps (VM, VL) EMG amplitude divided by the sum of average hamstrings (MH, BF) EMG amplitude for each trial. We used repeated-measures analyses of variance to compare Q:H ratios and individual muscle contributions across exercises (a ¼ .05), then used post hoc Tukey analyses.Results: We observed a main effect for exercise (F 3,79 ¼ 22.6, P , .001). The post hoc Tukey analyses revealed smaller Q:H ratios during the single-limb dead lift (2.87 6 1.77) than the single-limb squat (5.52 6 2.89) exercise. The largest Q:H ratios were observed during the transverse-lunge (7.78 6 5.51, P , .001), lateral-lunge (9.30 6 5.53, P , .001), and forward-lunge (9.70 6 5.90, P , .001) exercises.Conclusions: The most balanced (smallest) coactivation ratios were observed during the single-limb dead-lift, lateral-hop, transverse-hop, and lateral band-walk exercises. These exercises potentially could facilitate balanced activation in ACL rehabilitation and injury-prevention programs. They also could be used in postinjury rehabilitation programs in a safe and progressive manner.Key Words: anterior cruciate ligament, closed kinetic chain exercises Key PointsExercises that use a quadriceps-dominant activation might negatively affect the knee by increasing strain on the anterior cruciate ligament. The hamstrings muscles can counteract the deleterious effect of the quadriceps except when activation is minimal. The most balanced quadriceps-to-hamstrings coactivation ratios were produced during the single-limb dead-lift, lateral-hop, transverse-hop, and lateral band-walk exercises. Exercises with a more balanced quadriceps-to-hamstrings coactivation ratio may benefit anterior cruciate ligament rehabilitation and injury-prevention programs.

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“…The 2 tasks appear to challenge the neuromuscular system in different manners, and both should continue to be used in the investigation of injury risk. J Orthop Sports Phys Ther 2007;37 (5) 18,30,35 While there have been several studies examining electromyographic activity 2,14,38,39,42,43 and sagittal plane knee kinematics and kinetics during the step-down or single-leg squat task, 1,2,7 few studies have examined the frontal and transverse plane kinematics of these tasks. 6,43 A number of studies have investigated lower extremity biomechanics of men and women in an effort to explain the disparity in noncontact ACL injury rates between genders.…”

mentioning

confidence: 99%

Differences in Lower Extremity Kinematics Between a Bilateral Drop-Vertical Jump and A Single-Leg Step-down

Earl¹,

Monteiro²,

Snyder³

2007

J Orthop Sports Phys Ther

125

116

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Neuromuscular Control of the Knee during a Resisted Single-Limb Squat Exercise

Abstract: Background-Closed kinetic chain exercises such as single-limb squats are preferred for knee rehabilitation. A complete understanding of the neuromuscular control of the knee during the single-limb squat is essential to increase the efficiency of rehabilitation programs.

Cited by 71 publications

References 25 publications

Electromyographical Analysis of selected Lower Extremity Muscles During 5 Unilateral Weight-Bearing Exercises

Electromyographical Analysis of selected Lower Extremity Muscles During 5 Unilateral Weight-Bearing Exercises

Quadriceps and Hamstrings Coactivation During Common Therapeutic Exercises

Differences in Lower Extremity Kinematics Between a Bilateral Drop-Vertical Jump and A Single-Leg Step-down

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