Power Clean: Kinesiological evaluation

ArticleinStrength and conditioning journal 6(3) · June 1984with 338 Reads
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Abstract
The power clean is the current topic for the NSCA Journal feature "Bridging the Gap." Dr. John Garhammer presents the physiological aspects of the power clean. In the companion article, Harvey Newton discusses the practical aspects of instruction in the power clean. (C) 1984 National Strength and Conditioning Association

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  • Article
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    Weightlifting movements (e.g., the snatch, clean and jerk, and their derivatives) are frequently used within resistance training programs as a means of improving strength, power, speed, and coordination (1,16). As these exercises are incorporated into training plans, it is important to establish proper technique to reduce the risk of injury and maximize future training benefits (11,18,19). It is important that athletes obtain and utilize a proper power position (PP) when performing the pulling portion of a snatch or clean (or their derivatives) (12). The PP consists of the athlete standing with an upright torso and 60 – 70, 120 – 130, and 140 – 150 degree angles at the ankles, knees, and hips, respectively (3,12). For a more detailed explanation of the PP, readers should refer to the Hornsby et al. article in NSCA Coach 5.1, titled “The Power Position – Characteristics and Coaching Points” (12). The purpose of this article is to present and discuss the phases of the pull that precede the PP, as well as present some suggestions for how to coach these positions.
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    Study background: The power clean and its variations are prescribed by many collegiate and professional strength and conditioning coaches in order to train lower body muscular power. Lower body muscular power is an essential component to the overall performance of athletes in their respective sports. Although baseball is a sport that requires lower body power to be successful, it has not followed the trend of other sports that use Olympic lifts and their variations to train lower body power. Speculation leads practitioners to believe that baseball players consider Olympic lifts to be harmful to their shoulders and wrists because of the traditional overhead catch position of the snatch and jerk and the catch position of the power clean respectively. There are several power clean variations that produce high amounts of lower body power and may decrease the chance for injury to the shoulders and wrists. The high pull, jump shrug, and mid-thigh pull are three power clean variations that are used in the teaching progression of the power clean. Previous research indicated that the high pull, jump shrug, and mid-thigh pull can produce high amounts of lower body power that may be superior to a power clean variation that includes the catch phase. Because of the simplistic nature of these variations, it is likely the chance of injury to the shoulders and wrists will decrease. Conclusion: If there are power clean variations that can produce high amounts of lower body power and decrease the risk of injury to the shoulders and wrists of athletes, baseball strength and conditioning coaches should not be so quick to exclude all power clean variations from their strength training programs. Baseball strength and conditioning coaches should consider implementing the high pull, jump shrug, and mid-thigh pull into their strength training regimens.
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    The investment in learning required to reach benefit with weightlifting training is currently not well understood in elite athletes. The purpose of this investigation was to quantify changes in vertical jump power production and kinematic variables in hang power clean (HPC) performance during the learning process from a naïve state in a multiple single subject research design. Four elite athletes undertook HPC learning for approximately 20-30 min twice per week over a 169 day period. Changes in parameters of vertical power production during squat jump (SJ) and countermovement jump (CMJ) were monitored from baseline (day 0) and at three additional occasions. HPC movement kinematics and bar path traces were monitored from day 35 and at three additional occasions particular to the individual's periodised training plan. Descriptive statistics were reported within-athlete as mean ± SD. We observed a 14.1 - 35.7% (SJ) and a -14.4 - 20.5% (CMJ) gain in peak power across the four jump testing occasions with improvements over the first four weeks (SJ: 9.2 - 32.6%; CMJ: -2.91 - 20.79%). Changes in HPC movement kinematics and barbell path traces occurred for each athlete indicating a more rearward directed centre of pressure over the concentric phase, greater double knee bend during the transition phase, decreased maximal plantar flexion, and minimal vertical displacement of body mass with HPC learning. Considering the minimal investment of 4 weeks to achieve increases in vertical power production, the benefits of training with HPC justified the associated time costs for these four elite athletes.
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    The clean grip midthigh pull and snatch grip midthigh pull are exercises that focus on reinforcing the double knee bend and triple extension involved in weightlifting movements. As a result, these pulling movements are used with the purpose of making an athlete more efficient at producing force with an overload stimulus in the peak power position. In addition, these exercises can be used as a teaching modality for the progressive development of the full clean or snatch.
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    The jump shrug (JS) is an explosive lower-body exercise that can be used to enhance lower-body muscular power. In addition, this exercise can be used as part of the teaching progression of the clean and snatch, while emphasizing the second pull and complete extension of the hip, knee, and ankle joints. This exercise can be per-formed from a static starting position or with a countermovement, at varying starting positions, from the mid-thigh and above/below the knee.
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    The purpose of this study was to compare the power production of the hang clean (HC), jump shrug (JS), and high pull (HP) when performed at different relative loads. Seventeen men with previous HC training experience, performed 3 repetitions each of the HC, JS, and HP at relative loads of 30%, 45%, 65%, and 80% of their 1 repetition maximum (1RM) HC on a force platform over 3 different testing sessions. Peak power output (PPO), force (PF), and velocity (PV) of the lifter plus bar system during each repetition were compared. The JS produced a greater PPO, PF, and PV than both the HC (p < 0.001) and HP (p < 0.001). The HP also produced a greater PPO (p < 0.01) and PV (p < 0.001) than the HC. PPO, PF, and PV occurred at 45%, 65%, and 30% 1RM respectively. PPO at 45% 1RM was greater than PPO at 65% (p = 0.043) and 80% 1RM (p = 0.004). PF at 30% was less than PF at 45% (p = 0.006), 65% (p < 0.001), and 80% 1RM (p = 0.003). PV at 30% and 45% was greater than PV at 65% (p < 0.001) and 80% 1RM (p < 0.001). PV at 65% 1RM was also greater than PV at 80% 1RM (p < 0.001). When designing resistance training programs, practitioners should consider implementing the JS and HP. To optimize PPO, loads of approximately 30% and 45% 1RM HC are recommended for the JS and HP, respectively.
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    SPORTS REQUIRING EXPLOSIVE MOVEMENTS REQUIRE POWER PRODUCTION. A STRENGTH AND CONDITIONING PROGRAM SHOULD CONSIST OF EXERCISES THAT WILL PROMOTE POWER DEVELOPMENT IN THE ATHLETE. POWER CAN BE DEFINED AS THE PRODUCT OF A FORCE AND VELOCITY, WHICH CAN BE TRAINED AND INCREASED THROUGH RESISTED AND PLYOMETRIC MOVEMENTS. COMPLEX TRAINING CAN BE USED IN FORCE DEVELOPMENT AND YIELDS AN INCREASE IN POWER. THE PUBLISHED LITERATURE ON COMPLEX TRAINING DOES NOT NECESSARILY REFLECT THE PRACTICES OF COMPLEX TRAINING IN THE WEIGHT ROOM. THIS ARTICLE'S PURPOSE IS TO COMPARE THE SUGGESTIONS FROM THE LITERATURE AND STRENGTH AND CONDITIONING COACHES IN A PRACTICAL SETTING.
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    This case study evaluated the importance of peak bar velocity and starting posture adopted by a novice weightlifter to the outcome of a Snatch lift. Multiple observations of both successful and unsuccessful attempts were captured using 3D motion analysis (VICON MX: 500 Hz). The following data analysis was then used to derive feedback. In total, 133 attempts of loads ranging from 75 to 100% of 1 repetition maximum (1RM) were performed by the subject (age = 25 years, stature = 171 cm, mass = 74.8 kg, Snatch 1RM = 80 kg). Variables included peak bar velocity, pelvis, hip, knee and ankle joint angles at the starting position for the right side and the difference between (left minus right) sides. No main effects for load, success, or their interactions were found for peak bar velocity. Starting position kinematics were mostly nonsignificant between the outcome of Snatch attempts. Right ankle joint angle was the only exception, where unsuccessful attempts displayed greater (p = 0.0228) dorsiflexion. A more comprehensive finding was achieved through the partition modeling; this analysis provided valuable insight and coaching feedback for the subject in relation to his lower body kinematics at the starting position. Furthermore, the accuracy of this feedback was verified using a holdback data set. Specifically, anterior pelvic tilt (>17.6°) and hip joint (<89.6°) angle were identified as the key features to increasing the likelihood of success. In conclusion, this case study outlines a method of data collection and analysis to assist coaching feedback for an individual.
  • Article
    The purpose of this study was to determine the effect of load changes on angular accelerations of the ankle, knee and hip joints. Accelerations were measured in the squat (S), power clean (PC) and power hang clean (PHC), and compared to the accelerations in the push-off phase of the sprint start (SS). Methods: Nine female Division I college track athletes performed block sprint-starts, single-leg squat jumps (1S0) with 0% of 1RM, squats (jump) with 0, 25, 40% of 1RM, and PC and PHC with 30, 50, 75, 100% of 1RM. The fastest trial of each exercise was analyzed for minimum and maximum angular accelerations. A one-way, repeated measures ANOVA was used to determine any main effect among the variables between the exercises. Established effects were identified further using Least Square Difference post- hoc analysis. Results: Overall, angular accelerations differed mainly between groups of exercises (S vs. PC vs. PHC), less so within the groups (p < 0.05). Only for minimum angular knee joint acceleration in PHC and for minimum angular hip joint acceleration in S was change in acceleration significantly related to change in load. The ankle, knee and hip joint angular acceleration values in S, particularly the low-load S0, 1S0 and S25, were similar to the values measured in the SS. PC and PHC generally had smaller acceleration peaks, yet maximum angular knee and hip joint accelerations of all PCs and of PHC with 30% of 1RM approached the values of SS and S. Conclusion: Results suggest that light-load squat jumps emulate lower limb angular accelerations of the push-off phase in the sprint start much closer than medium- or heavy-load squats, or power cleans or power hang cleans. The lack of load dependency in PC and PHC should be studied further with athletes skilled in Olympic lifts.
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