The effects of load on system and lower-body joint kinetics during jump squats

Moir, Gavin L.; Gollie, Jared M.; Davis, Shala E.; Guers, John J.; Witmer, Chad A.

doi:10.1080/14763141.2012.725426

Cited by 33 publications

(31 citation statements)

References 29 publications

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“…As mentioned above, practitioners should be cautious when prescribing ''optimal loads,'' as previous research indicates that loads for peak power development may be specific for the lifter-plus-bar system [2, 27, 64, 69, 99-103, 117, 119] or barbell [109][110][111], or altered to specific joints [112][113][114][115]. Furthermore, the ''optimal load'' could change with trained state or accumulated fatigue, as determined by relative strength level [47].…”

Section: Loading For Peak Power Developmentmentioning

confidence: 97%

“…Taken collectively, these studies and coaching reviews indicate that the optimal load for peak power production of the lifter-plus-bar system occurs between 70 and 80 % 1RM for the clean, snatch, power clean, and hang power clean exercises, and between 90 and 95 % 1RM for weightlifting pulling derivatives. However, practitioners should be aware that optimal loads beyond the lifter-plusbar system exist, as several studies indicated that the optimal load for peak power production may also be specific to the barbell [109][110][111] or can be altered to specific joints [112][113][114][115]; thus, the optimal load may change based on the biomechanical approach being used to assess power.…”

Section: Previous Weightlifting Literaturementioning

confidence: 97%

“…In addition, high force movements may improve peak power and the load range of power development [52,143]. Finally, during the strength-power phase, the primary goal is the development of peak power, and therefore a range of loads should be prescribed, as previous research indicates that peak power may be specific to the lifter-plus-bar system [2, 27, 64, 69, 99-103, 117, 119] or barbell [109][110][111], or can be altered to specific joints [112][113][114][115]. Within this phase, a practitioner may consider implementing exercises such as the jump shrug because of its highly ballistic nature at loads of B45 % 1RM hang power clean to maximize peak velocity and peak power [64,69].…”

Section: Exercise Selectionmentioning

confidence: 99%

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Weightlifting Pulling Derivatives: Rationale for Implementation and Application

2015

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This review article examines previous weightlifting literature and provides a rationale for the use of weightlifting pulling derivatives that eliminate the catch phase for athletes who are not competitive weightlifters. Practitioners should emphasize the completion of the triple extension movement during the second pull phase that is characteristic of weightlifting movements as this is likely to have the greatest transference to athletic performance that is dependent on hip, knee, and ankle extension. The clean pull, snatch pull, hang high pull, jump shrug, and mid-thigh pull are weightlifting pulling derivatives that can be used in the teaching progression of the full weightlifting movements and are thus less complex with regard to exercise technique. Previous literature suggests that the clean pull, snatch pull, hang high pull, jump shrug, and mid-thigh pull may provide a training stimulus that is as good as, if not better than, weightlifting movements that include the catch phase. Weightlifting pulling derivatives can be implemented throughout the training year, but an emphasis and de-emphasis should be used in order to meet the goals of particular training phases. When implementing weightlifting pulling derivatives, athletes must make a maximum effort, understand that pulling derivatives can be used for both technique work and building strength-power characteristics, and be coached with proper exercise technique. Future research should consider examining the effect of various loads on kinetic and kinematic characteristics of weightlifting pulling derivatives, training with full weightlifting movements as compared to training with weightlifting pulling derivatives, and how kinetic and kinematic variables vary between derivatives of the snatch.

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Section: Loading For Peak Power Developmentmentioning

confidence: 97%

Section: Previous Weightlifting Literaturementioning

confidence: 97%

Section: Exercise Selectionmentioning

confidence: 99%

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Weightlifting Pulling Derivatives: Rationale for Implementation and Application

2015

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“…However, these velocities and forces only represent the overall net effect of all muscles that are acting in a coordinated fashion through multiple joints to effect the movement. Although total system power reflects the sum total of joint powers well for squats (Moir et al., ), maximal power for coordinated multi‐joint dynamic tasks such as leg extension is likely constrained by coordination rather than simultaneously maximizing power output of all contributing muscles and at all lower limb joints (Wakeling et al., ). Therefore, the resistance at which system power is maximized may not reflect the resistance at which each lower limb joint power output or individual muscle power output is maximized.…”

mentioning

confidence: 99%

Deconstructing the power resistance relationship for squats: A joint‐level analysis

Farris

Lichtwark

Brown³

et al. 2015

Scandinavian Med Sci Sports

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Generating high leg power outputs is important for executing rapid movements. Squats are commonly used to increase leg strength and power. Therefore, it is useful to understand factors affecting power output in squatting. We aimed to deconstruct the mechanisms behind why power is maximized at certain resistances in squatting. Ten male rowers (age = 20 ± 2.2 years; height = 1.82 ± 0.03 m; mass = 86 ± 11 kg) performed maximal power squats with resistances ranging from body weight to 80% of their one repetition maximum (1RM). Three-dimensional kinematics was combined with ground reaction force (GRF) data in an inverse dynamics analysis to calculate leg joint moments and powers. System center of mass (COM) velocity and power were computed from GRF data. COM power was maximized across a range of resistances from 40% to 60% 1RM. This range was identified because a trade-off in hip and knee joint powers existed across this range, with maximal knee joint power occurring at 40% 1RM and maximal hip joint power at 60% 1RM. A non-linear system force-velocity relationship was observed that dictated large reductions in COM power below 20% 1RM and above 60% 1RM. These reductions were due to constraints on the control of the movement.

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“…Thus, when considering the internal (joint) kinetics, the PJ is more similar in those athletes who are knee dominant jumpers. Taking into regard, the continuum of general to specific exercises for sports performance, for those athletes who adopted more hip dominant strategies the PJ may be a more general exercise and movements considered to produce more hip moment, such as jump squats (29), could instead be used as a more specific exercise for these athletes. Further research in various movements may add further insight into this matter.…”

Section: Introductionmentioning

confidence: 99%

Relative Intensity Influences the Degree of Correspondence of Jump Squats and Push Jerks to Countermovement Jumps

Cushion

Goodwin

Cleather

2016

Journal of Strength and Conditioning Research

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The aim of this study was to determine the mechanical similarity between push jerk (PJ) and jump squat (JS) to countermovement jump (CMJ) and further understand the effect increasing external load may have on this relationship. Eight physically trained men (age 22 ± 3; height 176 ± 7 kg; weight 83 ± 8 kg) performed an unloaded CMJ followed by JS under a range of loads (10, 25, 35, and 50% 1RM back squat) and PJ (30, 50, 65, and 75% 1RM push jerk). A portable force platform and high-speed camera both collecting at 250 Hz were used to establish joint moments and impulse during the propulsive phase of the movements. A standard inverse dynamics model was used to determine joint moment and impulse at the hip, knee, and ankle. Significant correlations (p ≤ 0.05) were shown between CMJ knee joint moment and JS knee joint moment at 25% load and PJ knee joint moment at 30 and 50% load. Significant correlations were also observed between CMJ knee joint impulse and JS knee joint impulse at 10% load and PJ knee joint moment at 30 and 65% load. Significant correlation was also observed between CMJ hip joint impulse and PJ hip joint impulse at 30% load. No significant joint × load interaction was shown as load increased for either PJ or JS. Results from the study suggest partial correspondence between PJ and JS to CMJ, where a greater mechanical similarity was observed between the PJ and CMJ. This interaction is load and joint dependent where lower relative loads showed greatest mechanical similarity. Therefore using lower relative loads when programming may provide a greater transfer of training effect.

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The effects of load on system and lower-body joint kinetics during jump squats

Cited by 33 publications

References 29 publications

Weightlifting Pulling Derivatives: Rationale for Implementation and Application

Weightlifting Pulling Derivatives: Rationale for Implementation and Application

Deconstructing the power resistance relationship for squats: A joint‐level analysis

Relative Intensity Influences the Degree of Correspondence of Jump Squats and Push Jerks to Countermovement Jumps

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