The effect of different decline angles on the biomechanics of double limb squats and the implications to clinical and training practice (original) (raw)
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Horizontal and Declined Squats in Healthy Individuals: A Study of Kinematic and Muscle Patterns
ISRN Rehabilitation, 2013
Squats are frequently incorporated in physiotherapy programmes and performed in different ways. Accordingly, muscle and kinematic patterns also differ. The objective was to compare the kinematics and EMG patterns of the major muscles of knee and ankle joints during different squat exercises on horizontal (HP) and 25 ∘ decline (DP) boards. Seventeen healthy individuals performed squats on HP and DP with bilateral support and restriction of trunk movements in the sagittal plane. The knee and ankle angular displacements in the sagittal plane and the EMG activities of the major muscles of the lower limb in four subphases of movement were recorded and analyzed. For the descending phase of the HP squats, the angular excursion, as well as the initial and final positions, was smaller for the knee ( < 0.05) but larger for the ankle ( = 0.01). For the ascending phase of the HP squats, the initial and final positions were larger for the ankle ( < 0.02) and the final position was smaller for the knee ( = 0.05). All muscles remained activated and showed similarity between the tasks ( > 0.44), except for the tibialis anterior in both squat exercises ( < 0.03). The HP and DP squats produced different kinematics (knee and ankle joints) but did not modify the EMG strategy for both movement phases. of Hindawi Publishing Corporation
Baltic Journal of Health and Physical Activity, 2018
Background: Bipedal leg squat is a common rehabilitation exercise. It is used for evaluation of lower limb function and pelvis and core stability. The aim of this study was a comparison of the lower limb, pelvis and spine ranges of motion in subjects with different declared physical activity level during bipedal squat. Material and methods: Twenty healthy student-volunteers took part in this investigation. Based on the author's questionnaire, they were divided into two groups: "higher" and "lower" physical activity level. Participants performed a two-leg squat with maximal depth, and returned to the standing position. The tridimensional motion of the ankle, knee, hip, pelvis and spine was analysed. Results: During a bipedal squat the more active subjects demonstrate a greater ankle range of motion (42.585 deg) and smaller pelvis (17.293 deg) and spine (40.228 deg) mobility in the sagittal plane than the less active participants (33.819 deg, 29.178 deg and 63.279 deg respectively). The more active group demonstrate a decreased motion of the ankle in the frontal plane (4.173 deg; 10.839 deg, p = 0.006) and an increased motion of the hip in the transverse plane (39.765deg; 27.971 deg, p = 0.035) than less the active one. Conclusions: The level of activity can lead to different movement patterns during multi-joint exercises.
Influence of pistol squat on decline angle and hamstring muscle activity in an healthy population
Journal of Kinesiology and Exercise Sciences, 2021
Background: Modern lifestyle and physically inactive society is one of the most common causes of the reduced knee joint mobility. Underactive and uneven distribution of stresses on the knee joint is one the main causes for decreased joint stability and flexibility. Aim: the purpose of the study is to know the Influence of pistol squat over decline angle and Hamstring muscle activity of healthy population. Methodology: It is a Quasi Experimental Study design, of about 20 subjects aged 18 to 25 years and both male and female healthy population were included in the study. Ordinal scale was used to assess the Decline angle of knee range of motion. Subjects were asked to perform pistol squat and the muscle activity of Hamstring was analyzed through Electromyography and 6 weeks Pistol squat protocol training was given. Then, the pre-test and post-test values were compared by using paired sample t test and Chi square test. Results: shows that there is a significant change in Muscle activit...
Context: Limitations in gastrocnemius/soleus flexibility that restrict ankle dorsiflexion during dynamic tasks have been reported in individuals with patellofemoral pain (PFP) and are theorized to play a role in its development. Objective: To determine the effect of restricted ankle-dorsiflexion range of motion (ROM) on lower extremity kinematics and muscle activity (EMG) during a squat. The authors hypothesized that restricted ankle-dorsiflexion ROM would alter knee kinematics and lower extremity EMG during a squat. Design: Cross-sectional. Participants: 30 healthy, recreationally active individuals without a history of lower extremity injury. Interventions: Each participant performed 7 trials of a double-leg squat under 2 conditions: a no-wedge condition (NW) with the foot flat on the floor and a wedge condition (W) with a 12° forefoot angle to simulate reduced plantar-flexor flexibility. Main Outcome Measures: 3-dimensional hip and knee kinematics, medial knee displacement (MKD), and ankle-dorsiflexion angle. EMG of vastus medialis oblique (VMO), vastus lateralis (VL), lateral gastrocnemius (LG), and soleus (SOL). One-way repeated-measures ANOVAs were performed to determine differences between the W and NW conditions. Results: Compared with the NW condition, the wedge produced decreased peak knee flexion (P < .001, effect size [ES] = 0.81) and knee-flexion excursion (P < .001, ES = 0.82) while producing increased peak ankle dorsiflexion (P = .006, ES = 0.31), ankle-dorsiflexion excursion (P < .001, ES = 0.31), peak knee-valgus angle (P = .02, ES = 0.21), and MKD (P < .001, ES = 2.92). During the W condition, VL (P = 0.002, ES = 0.33) and VMO (P = .049, ES = 0.20) activity decreased while soleus activity increased (P = .03, ES = 0.64) compared with the NW condition. No changes were seen in hip kinematics (P > .05). Conclusions: Altering ankle-dorsiflexion starting position during a double-leg squat resulted in increased knee valgus and MKD, as well as decreased quadriceps activation and increased soleus activation. These changes are similar to those seen in people with PFP.
Knee biomechanics of the dynamic squat exercise
Medicine & Science in Sports & Exercise, 2001
Purpose: 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. Methods: 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. Results: 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°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°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°knee flexion. Furthermore, it was demonstrated that the parallel squat was not injurious to the healthy knee. Conclusions: 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.
Kinesiology Corner: Analysis of the Squat
National Strength Coaches Association Journal, 1981
The aim of this study was to perform an electromyography comparison of three commonly used lower limb injury prevention exercises: a single-leg squat on a bench (SLSB), a double-leg squat (DLS) and a double-leg squat on a BOSU® balance trainer (DLSB). After determining the maximum isometric voluntary contraction of the hamstring and quadriceps, eight female athletes performed 3 repetitions of each exercise, while electromyography activity of the biceps femoris (BF), semitendinosus (ST), vastus lateralis (VL) and vastus medialis (VM) was monitored. Comparisons between exercises revealed higher activation in BF
Kinematic, kinetic and EMG patterns during downward squatting
… of Electromyography and …, 2008
The aim of this study was to investigate the kinematic, kinetic, and electromyographic pattern before, during and after downward squatting when the trunk movement is restricted in the sagittal plane. Eight healthy subjects performed downward squatting at two different positions, semisquatting (40°knee flexion) and half squatting (70°knee flexion). Electromyographic responses of the vastus medialis oblique, vastus medialis longus, rectus femoris, vastus lateralis, biceps femoris, semitendineous, gastrocnemius lateralis, and tibialis anterior were recorded. The kinematics of the major joints were reconstructed using an optoelectronic system. The center of pressure (COP) was obtained using data collected from one force plate, and the ankle and knee joint torques were calculated using inverse dynamics. In the upright position there were small changes in the COP and in the knee and ankle joint torques. The tibialis anterior provoked the disruption of this upright position initiating the squat. During the acceleration phase of the squat the COP moved posteriorly, the knee joint torque remained in flexion and there was no measurable muscle activation. As the body went into the deceleration phase, the knee joint torque increased towards extension with major muscle activities being observed in the four heads of the quadriceps. Understanding these kinematic, kinetic and EMG strategies before, during and after the squat is expected to be beneficial to practitioners for utilizing squatting as a task for improving motor function.
The Effects of Technique Variations on Knee Biomechanics During the Squat and Leg Press 887
Medicine & Science in Sports & Exercise, 1997
Purpose: The specific aim of this project was to quantify knee forces and muscle activity while performing squat and leg press exercises with technique variations. Methods: Ten experienced male lifters performed the squat, a high foot placement leg press (LPH), and a low foot placement leg press (LPL) employing a wide stance (WS), narrow stance (NS), and two foot angle positions (feet straight and feet turned out 30°). Results: No differences were found in muscle activity or knee forces between foot angle variations. The squat generated greater quadriceps and hamstrings activity than the LPH and LPL, the WS-LPH generated greater hamstrings activity than the NS-LPH, whereas the NS squat produced greater gastrocnemius activity than the WS squat. No ACL forces were produced for any exercise variation. Tibiofemoral (TF) compressive forces, PCL tensile forces, and patellofemoral (PF) compressive forces were generally greater in the squat than the LPH and LPL, and there were no differences in knee forces between the LPH and LPL. For all exercises, the WS generated greater PCL tensile forces than the NS, the NS produced greater TF and PF compressive forces than the WS during the LPH and LPL, whereas the WS generated greater TF and PF compressive forces than the NS during the squat. For all exercises, muscle activity and knee forces were generally greater in the knee extending phase than the knee flexing phase. Conclusions: The greater muscle activity and knee forces in the squat compared with the LPL and LPH implies the squat may be more effective in muscle development but should be used cautiously in those with PCL and PF disorders, especially at greater knee flexion angles. Because all forces increased with knee flexion, training within the functional 0-50°range may be efficacious for those whose goal is to minimize knee forces. The lack of ACL forces implies that all exercises may be effective during ACL rehabilitation.
Journal of athletic training, 2015
Poor dynamic limb alignment during loading tasks has links to the development of knee injuries, including patellofemoral pain and anterior cruciate ligament injury. Therefore, modalities to improve limb alignment during loading tasks are thought to reduce loading through these structures and potentially prevent injury. To compare hip-strengthening and skill-acquisition training to examine if they can improve lower limb biomechanics, potentially preventing injury, and to examine whether changes demonstrated can be maintained after 6 weeks of no practice. Controlled laboratory study. Laboratory. A total of 19 recreationally active individuals volunteered, and 17 (9 women: age = 27.9 ± 3.1 years, height = 165.4 ± 8.4 cm, mass = 60.5 ± 9.2 kg; 8 men: age = 30.4 ± 6.4 years, height = 181.4 ± 7.1 cm, mass = 69.8 ± 15.2 kg) completed the study. Nine participants were allocated to a hip-strengthening program; 8, to a skill-acquisition program. Participants performed a 6-week training progra...