Faster Movement Speed Results in Greater Tendon Strain during the Loaded Squat Exercise

Earp, Jacob E.; Newton, Robert U.; Cormie, Prue; Blazevich, Anthony J.

doi:10.3389/fphys.2016.00366

Cited by 21 publications

(31 citation statements)

References 29 publications

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“…As a result, the ground reaction forces and forces acting on the muscletendon unit are higher during the initiation of the upward movement in the CMJ as compared with the forces acting on the muscle-tendon unit in the starting position of the SJ. The tendinous tissues are stretched more during the countermovement as a result of these higher forces (3,4,23,45), resulting in a higher stiffness of the tendinous tissues. This higher stiffness may allow the muscle fibers to shorten at a slower velocity, thereby increasing their force-producing capability and CMJ performance (30).…”

Section: Reduction Of Muscle Slack and Buildup Of Stimulationmentioning

confidence: 99%

The Difference Between Countermovement and Squat Jump Performances: A Review of Underlying Mechanisms With Practical Applications

Hooren¹,

Zolotarjova

2017

Journal of Strength and Conditioning Research

177

127

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Van Hooren, B and Zolotarjova, J. The difference between countermovement and squat jump performances: a review of underlying mechanisms with practical applications. J Strength Cond Res 31(7): 2011-2020, 2017-Two movements that are widely used to monitor athletic performance are the countermovement jump (CMJ) and squat jump (SJ). Countermovement jump performance is almost always better than SJ performance, and the difference in performance is thought to reflect an effective utilization of the stretch-shortening cycle. However, the mechanisms responsible for the performance-enhancing effect of the stretch-shortening cycle are frequently undefined. Uncovering and understanding these mechanisms is essential to make an inference regarding the difference between the jumps. Therefore, we will review the potential mechanisms that explain the better performance in a CMJ as compared with a SJ. It is concluded that the difference in performance may primarily be related to the greater uptake of muscle slack and the buildup of stimulation during the countermovement in a CMJ. Elastic energy may also have a small contribution to an enhanced CMJ performance. Therefore, a larger difference between the jumps is not necessarily a better indicator of high-intensity sports performance. Although a larger difference may reflect the utilization of elastic energy in a small-amplitude CMJ as a result of a well-developed capability to co-activate muscles and quickly build up stimulation, a larger difference may also reflect a poor capability to reduce the degree of muscle slack and build up stimulation in the SJ. Because the capability to reduce the degree of muscle slack and quickly build up stimulation in the SJ may be especially important to high-intensity sports performance, training protocols might concentrate on attaining a smaller difference between the jumps.

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Section: Reduction Of Muscle Slack and Buildup Of Stimulationmentioning

confidence: 99%

The Difference Between Countermovement and Squat Jump Performances: A Review of Underlying Mechanisms With Practical Applications

Hooren¹,

Zolotarjova

2017

Journal of Strength and Conditioning Research

177

127

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“…Seven of them were competitive powerlifters (National Academic Championships) and five of them were preparing for their first competition. They were classified as experienced in resistance training and performing squats (training experience 5.0 ± 1.7 years, 1RM HBBS /BM 1.6 ± 0.3, 1RM LBBS /BM 1.7 ± 0.2) (Earp et al, 2016;Banyard et al, 2017;Shariat et al, 2017;Hammer, Linton & Hammer, 2018). 1RM for HBBS and LBBS were set separately during training sessions (one week apart).…”

Section: Participantsmentioning

confidence: 99%

Muscle activation varies between high-bar and low-bar back squat

Murawa¹,

Fryzowicz²,

Kabaciński³

et al. 2020

PeerJ

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Background Differences in the muscular activity between the high-bar back squat (HBBS) and the low-bar back squat (LBBS) on the same representative group of experienced powerlifters are still scarcely investigated. The main purpose of the study was to compare the normalized bioelectrical activity and maximal angles within single homogeneous group between the HBBS and LBBS for 60% one repetition maximum (1RM), 65% 1RM and 70% 1RM. Methods Twelve healthy men (age 24.3 ± 2.8 years, height 178.8 ± 5.6 cm, body mass 88.3 ± 11.5 kg), experienced in powerlifting performed HBBS and LBBS with comparable external loads equal 60% 1RM, 65% 1RM, and 70% 1RM. Electromyography (EMG) signals of muscle groups were synchronously recorded alongside kinematic data (joints angle) by means of a motion capture system. Results EMG activity during eccentric phase of squat motion were significantly higher during LBBS than in HBBS for all selected muscles (60% 1RM and 65% 1RM) (p < 0.05). All examined muscles were more activated during concentric phase of the squat cycle (p < 0.05). In the concentric phase, significant differences between the loads were generally not observed between just 5% 1RM change in load level for LBBS. Conclusions Our results confirmed significant differences in muscles activation between both squat techniques. Muscle activity during eccentric phase of squat motion were significantly higher during LBBS than HBBS. The differences are crucial for posterior muscle chain during eccentric phase of squat cycle.

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“…Due to the increased movement time, the athlete is not forced to quickly build-up activation and this capability may therefore not be effectively be trained. Additionally, an external load may take up muscle slack by taking slack out of the fascicles and tendinous tissues, by aligning the muscle-tendon unit and stretching the tendinous tissues, hereby allowing a more rapid force development compared to when no external load is used (19,63,64). This may lead to more muscle slack in movements without external load because the athlete's capability to perform co-contractions and hence take up muscle slack may be reduced as a consequence of the supporting effect of external load (63).…”

Section: Mechanisms Of Rapid Force Developmentmentioning

confidence: 99%

Can Resistance Training Enhance the Rapid Force Development in Unloaded Dynamic Isoinertial Multi-Joint Movements? A Systematic Review

Hooren

Bosch

Meijer³

2017

Journal of Strength and Conditioning Research

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Van Hooren, B, Bosch, F, and Meijer, K. Can resistance training enhance the rapid force development in unloaded dynamic isoinertial multi-joint movements? A systematic review. J Strength Cond Res 31(8): 2324-2337, 2017-The objectives of this systematic review were to (a) evaluate whether resistance training can improve the rapid force development in unloaded dynamic isoinertial multi-joint movements and (b) investigate whether these effects differ between untrained/recreationally trained and well-trained individuals. Four electronic databases were screened for studies that measured the effects of resistance training on rapid force development in unloaded dynamic isoinertial multi-joint movements. Twelve studies with a total of 271 participants were included. 10/26 (38%) and 6/14 (43%) of the measures of rapid force development in unloaded dynamic isoinertial multi-joint movements significantly improved following training in the untrained/recreationally trained and well-trained individuals, respectively. Additionally, 7/14 (50%) and 3/12 (25%) of the measures significantly improved during a countermovement and squat jump in the untrained/recreationally trained individuals and 4/6 (67%) and 2/8 (25%) significantly improved during a countermovement and squat jump in the well-trained individuals, respectively. These findings indicate that resistance training has a limited transfer to rapid force development in unloaded dynamic isoinertial multi-joint movements, especially for well-trained individuals and in movements without a countermovement. Furthermore, rapid force development has likely a limited transfer from movements with countermovement to movements without a countermovement and from bilateral movements to unilateral movements. Therefore, it is important to specifically mimic the actual sport movement in order to maximize the transfer of training and testing.

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Faster Movement Speed Results in Greater Tendon Strain during the Loaded Squat Exercise

Cited by 21 publications

References 29 publications

The Difference Between Countermovement and Squat Jump Performances: A Review of Underlying Mechanisms With Practical Applications

The Difference Between Countermovement and Squat Jump Performances: A Review of Underlying Mechanisms With Practical Applications

Muscle activation varies between high-bar and low-bar back squat

Can Resistance Training Enhance the Rapid Force Development in Unloaded Dynamic Isoinertial Multi-Joint Movements? A Systematic Review

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