Effects of load on ground reaction force and lower limb kinematics during concentric squats

Kellis, Eleftherios; Arambatzi, Fotini; Papadopoulos, Christos

doi:10.1080/02640410400022094

Cited by 52 publications

(34 citation statements)

References 28 publications

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“…Second, in a recent study Nuzzo and co-workers (2010b) unloaded body by a counter-mass hanging onto a cable-pulley system that reduced the weight, but inevitably also increased inertia, which likely confounded the observed outcomes (Leontijevic et al 2012). Third, the application of the external load at the subject's shoulders, as performed by Argus et al (2011), could affect the jumping mechanics (Kellis et al 2005). Furthermore, the former study used short (i.e.…”

Section: Discussionmentioning

confidence: 99%

Power output in vertical jumps: does optimum loading depend on activity profiles?

et al. 2012

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The previously proposed Maximum Dynamic Output hypothesis (MDO; i.e. the optimum load for maximizing the power output during jumping is one's own body) was tested on individuals of various activity profiles. Forty males (10 strength-trained athletes, 10 speed-trained athletes, 10 physically active non-athletes, and 10 sedentary individuals) performed different vertical jumps on a force plate while a pulley system was used to either reduce or increase the subject's body weight by 10–30%. As expected, an increase in external loading resulted in a significant increase (p < 0.001) in force output and a concomitant decrease of peak jumping velocity in all groups of participants. The main finding, however, was that all groups revealed the maximum peak and mean power output at approximately the subjects’ own body weight although their weight represented prominently different percentage of their maximum dynamic strength. While a significant (p < 0.05), albeit moderate, 'group × load' interaction in one jump was observed for the peak power output, the individual optimum load for maximizing the power output number did not differ among the groups. Although apparently further research on various types of movements is needed, the present results provide, so far, the strongest support of the MDO hypothesis.

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Section: Discussionmentioning

confidence: 99%

Power output in vertical jumps: does optimum loading depend on activity profiles?

et al. 2012

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“…Clark, Lambert, and Hunter (2012) emphasised that the sub-maximal load used in Gullet's study might have failed to elicit the possible difference between back and front squat. Furthermore, an increase in trunk forward lean was shown with higher loads by Hay, Andrews, Vaughan, and Ueya (1983) and Kellis, Arambatzi, and Papadopoulos (2005) during squat. Therefore obviously, squat kinematics and EMG signalisation pattern can change with maximal loading.…”

Section: Introductionmentioning

confidence: 89%

Kinematic and EMG activities during front and back squat variations in maximum loads

Yavuz

Erdağ

Amca

et al. 2015

Journal of Sports Sciences

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The aim of this study was to compare the musculature activity and kinematics of knee and hip joints during front and back squat with maximal loading. Two-dimensional kinematical data were collected and electromyographic activities of vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus and erector spinae were measured while participants (n = 12, 21.2 ± 1.9 years old) were completing front and back squat exercises with maximum loading. Paired sample t-test was used for comparisons between two techniques. Results showed that the electromyographic activity of vastus medialis was found to be greater in the front squat compared to the back squat during the ascending phase (P < 0.05, d = 0.62; 95% CI, -15.0/-4.17) and the whole manoeuvre (P < 0.05, d = 0.41; 95% CI, -12.8/-0.43), while semitendinosus (P < 0.05, d = -0.79; 95% CI, 0.62/20.59) electromyographic activity was greater in the back squat during the ascending phase. Compared to the front squat version, back squat exhibited significantly greater trunk lean, with no differences occurring in the knee joint kinematics throughout the movement. Results may suggest that the front squat may be preferred to the back squat for knee extensor development and for preventing possible lumbar injuries during maximum loading.

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“…Knowing how load affects movement kinematics and electromyography (EMG) activity allows the role of load in resistance training to not only control for intensity, but to also improve specificity, as certain loads may better mimic other movements, especially those in sport. Kellis et al (2005) found that as Smith-machine barbell load increased for the concentric squat from 7 to 70% of one repetition maximum (1RM), hip, knee, and ankle angles were significantly affected. In Hay et al (1983), it was revealed that there is a progressive increase in trunk inclination, that is, the trunk being more horizontal, at the start of the barbell squat as external load is increased.…”

Section: Reviewing Manuscriptmentioning

confidence: 99%

Peer Review #2 of "Effects of load on good morning kinematics and EMG activity (v0.1)"

2015

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Many strength and conditioning coaches utilize the good morning (GM) to strengthen the hamstrings and spinal erectors. However, little research exists on its electromyography (EMG) activity and kinematics, and how these variables change as a function of load. The purpose of this investigation was to examine how estimated hamstring length, integrated EMG (IEMG) activity of the hamstrings and spinal erectors, and kinematics of the lumbar spine, hip, knee, and ankle are affected by changes in load. Fifteen trained male participants (age = 24.6 ± 5.3 years; body mass = 84.7 ± 11.3 kg; height = 180.9 ± 6.8 cm) were recruited for this study. Participants performed five sets of the GM, utilizing 50, 60, 70, 80, and 90% of one-repetition maximum (1RM) in a randomized fashion. IEMG activity of hamstrings and spinal erectors tended to increase with load. Knee flexion increased with load on all trials. Estimated hamstring length decreased with load.However, lumbar flexion, hip flexion, and plantar flexion experienced no remarkable changes between trials. These data provide insight as to how changing the load of the GM affects EMG activity, kinematic variables, and estimated hamstring length. Implications for hamstring injury prevention are discussed. More research is needed for further insight as to how load affects EMG activity and kinematics of other exercises.PeerJ reviewing PDF |

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Effects of load on ground reaction force and lower limb kinematics during concentric squats

Cited by 52 publications

References 28 publications

Power output in vertical jumps: does optimum loading depend on activity profiles?

Power output in vertical jumps: does optimum loading depend on activity profiles?

Kinematic and EMG activities during front and back squat variations in maximum loads

Peer Review #2 of "Effects of load on good morning kinematics and EMG activity (v0.1)"

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