Kinetic comparison of the power development between power clean variations

Portions of the force-velocity relationship targeted by weightlifting exercises

We compared the force-velocity (F-V) characteristics between jump squat (JS) and weightlifting (hang clean [HC] and HC pull [HCP]) to determine lower limb F-V portions targeted by weightlifting exercises. Ten weightlifters performed JS at 0% (body weight only) to 70% of their one-repetition maximum (1RM) for back squat, and HC and HCP at 30‒90% and 30‒110% of their 1RM for HC, respectively. Force and velocity values at each relative load were plotted to determine the F-V features of JS, HC, and HCP. Linear regression was used to evaluate each participant's JS F-V results to obtain individual F-V relationships. Regression equations evaluated the JS force at a given velocity for each relative load of HC and HCP. HC produced significantly less force than JS at given velocities for 30%, 40%, and 50% 1RM. Furthermore, HCP produced significantly less force than JS at a given velocity for 30% 1RM and exhibited less force than JS at a given velocity for 40% 1RM with moderate effect size. HC and HCP produce comparable forces to JS within the velocity ranges of 60‒90% and 50‒110% 1RM, respectively. Thus, weightlifting exercises target low‒moderate-velocity portion of the lower limb F-V relationship.

No differences in weightlifting overhead pressing exercises kinetics

This study aimed to compare the kinetics between the push press (PP), push jerk (PJ), and split jerk (SJ). Sixteen resistance-trained participants (12 men and 4 women; age: 23.8 ± 4.4 years; height: 1.7 ± 0.1 m; body mass: 75.7 ± 13.0 kg; weightlifting experience: 2.2 ± 1.3 years; one repetition maximum [1RM] PP: 76.5 ± 19.5 kg) performed 3 repetitions each of the PP, PJ, and SJ at a relative load of 80% 1RM PP on a force platform. The kinetics (peak and mean force, peak and mean power, and impulse) of the PP, PJ, and SJ were determined during the dip and thrust phases. Dip and thrust displacement and duration were also calculated for the three lifts. In addition, the inter-repetition reliability of each variable across the three exercises was analysed. Moderate to excellent reliability was evident for the PP (Intraclass correlation coefficient [ICC] = 0.91-1.00), PJ (ICC = 0.86-1.00), and SJ (ICC = 0.55-0.99) kinetics. A one-way analysis of variance revealed no significant or meaningful differences (p > 0.05, η2 ≤ 0.010) for any kinetic measure between the PP, PJ, and SJ. In conclusion, there were no differences in kinetics between the PP, PJ, and SJ when performed at the same standardised load of 80% 1RM PP.

Using Barbell Acceleration to Determine the 1 Repetition Maximum of the Jump Shrug

ABSTRACT

Techmanski, BS, Kissick, CR, Loturco, I, and Suchomel, TJ. Using barbell acceleration to determine the 1 repetition maximum of the jump shrug. J Strength Cond Res 38(8): 1486-1493, 2024-The purpose of this study was to determine the 1 repetition maximum (1RM) of the jump shrug (JS) using the barbell acceleration characteristics of repetitions performed with relative percentages of the hang power clean (HPC). Fifteen resistance-trained men (age = 25.5 ± 4.5 years, body mass = 88.5 ± 15.7 kg, height = 176.1 ± 8.5 cm, relative 1RM HPC = 1.3 ± 0.2 kg·kg-1) completed 2 testing sessions that included performing a 1RM HPC and JS repetitions with 20, 40, 60, 80, and 100% of their 1RM HPC. A linear position transducer was used to determine concentric duration and the percentage of the propulsive phase (P%) where barbell acceleration was greater than gravitational acceleration (i.e., a>-9.81 m·s-2). Two 1 way repeated measures ANOVA were used to compare each variable across loads, whereas Hedge's g effect sizes were used to examine the magnitude of the differences. Concentric duration ranged from 449.7 to 469.8 milliseconds and did not vary significantly between loads (p = 0.253; g = 0.20-0.39). The P% was 57.4 ± 7.2%, 64.8 ± 5.9%, 73.2 ± 4.3%, 78.7 ± 4.0%, and 80.3 ± 3.5% when using 20, 40, 60, 80, and 100% 1RM HPC, respectively. P% produced during the 80 and 100% 1RM loads were significantly greater than those at 20, 40, and 60% 1RM (p < 0.01, g = 1.30-3.90). In addition, P% was significantly greater during 60% 1RM compared with both 20 and 40% 1RM (p < 0.01, g = 1.58-2.58) and 40% was greater than 20% 1RM (p = 0.003, g = 1.09). A braking phase was present during each load and, thus, a 1RM JS load was not established. Heavier loads may be needed to achieve a 100% propulsive phase when using this method.

Can the Velocity of a 1RM Hang Power Clean Be Used to Estimate a 1RM Hang High Pull?

ABSTRACT

Suchomel, TJ, Techmanski, BS, Kissick, CR, and Comfort, P. Can the velocity of a 1RM hang power clean be used to estimate a 1RM hang high pull? J Strength Cond Res 38(7): 1321-1325, 2024-The purpose of this study was to estimate the 1-repetition maximum hang high pull (1RM HHP) using the peak barbell velocity of a 1RM hang power clean (HPC). Fifteen resistance-trained men (age = 25.5 ± 4.5 years, body mass = 88.3 ± 15.4 kg, height = 176.1 ± 8.5 cm, relative 1RM HPC = 1.3 ± 0.2 kg·kg-1) with previous HPC experience participated in 2 testing sessions that included performing a 1RM HPC and HHP repetitions with 20, 40, 60, and 80% of their 1RM HPC. Peak barbell velocity was measured using a linear position transducer during the 1RM HPC and HHP repetitions performed at each load. The peak barbell velocity achieved during the 1RM HPC was determined as the criterion value for a 1RM performance. Subject-specific linear regression analyses were completed using slope-intercept equations created from the peak velocity of the 1RM HPC and the peak barbell velocities produced at each load during the HHP repetitions. The peak barbell velocity during the 1RM HPC was 1.74 ± 0.30 m·s-1. The average load-velocity profile showed that the estimated 1RM HHP of the subjects was 98.0 ± 19.3% of the 1RM HPC. Although a 1RM HHP value may be estimated using the peak barbell velocity during the HPC, strength and conditioning practitioners should avoid this method because of the considerable variation within the measurement. Additional research examining different methods of load prescription for weightlifting pulling derivatives is needed.

National Strength and Conditioning Association Position Statement on Weightlifting for Sports Performance

ABSTRACT

Comfort, P, Haff, GG, Suchomel, TJ, Soriano, MA, Pierce, KC, Hornsby, WG, Haff, EE, Sommerfield, LM, Chavda, S, Morris, SJ, Fry, AC, and Stone, MH. National Strength and Conditioning Association position statement on weightlifting for sports performance. J Strength Cond Res XX(X): 000-000, 2022-The origins of weightlifting and feats of strength span back to ancient Egypt, China, and Greece, with the introduction of weightlifting into the Olympic Games in 1896. However, it was not until the 1950s that training based on weightlifting was adopted by strength coaches working with team sports and athletics, with weightlifting research in peer-reviewed journals becoming prominent since the 1970s. Over the past few decades, researchers have focused on the use of weightlifting-based training to enhance performance in nonweightlifters because of the biomechanical similarities (e.g., rapid forceful extension of the hips, knees, and ankles) associated with the second pull phase of the clean and snatch, the drive/thrust phase of the jerk and athletic tasks such as jumping and sprinting. The highest force, rate of force development, and power outputs have been reported during such movements, highlighting the potential for such tasks to enhance these key physical qualities in athletes. In addition, the ability to manipulate barbell load across the extensive range of weightlifting exercises and their derivatives permits the strength and conditioning coach the opportunity to emphasize the development of strength-speed and speed-strength, as required for the individual athlete. As such, the results of numerous longitudinal studies and subsequent meta-analyses demonstrate the inclusion of weightlifting exercises into strength and conditioning programs results in greater improvements in force-production characteristics and performance in athletic tasks than general resistance training or plyometric training alone. However, it is essential that such exercises are appropriately programmed adopting a sequential approach across training blocks (including exercise variation, loads, and volumes) to ensure the desired adaptations, whereas strength and conditioning coaches emphasize appropriate technique and skill development of athletes performing such exercises.

Reliability, Validity, and Comparison of Barbell Velocity Measurement Devices during the Jump Shrug and Hang High Pull

This study examined the reliability, potential bias, and practical differences between the GymAware Powertool (GA), Tendo Power Analyzer (TENDO), and Push Band 2.0 (PUSH) during the jump shrug (JS) and hang high pull (HHP) performed across a spectrum of loads. Fifteen resistance-trained men performed JS and HHP repetitions with 20, 40, 60, 80, and 100% of their 1RM hang power clean, and mean (MBV) and peak barbell velocity (PBV) were determined by each velocity measurement device. Least-products regression and Bland-Altman plots were used to examine instances of proportional, fixed, and systematic bias between the TENDO and PUSH compared to the GA. Hedge's g effect sizes were also calculated to determine any meaningful differences between devices. The GA and TENDO displayed excellent reliability and acceptable variability during the JS and HHP while the PUSH showed instances of poor-moderate reliability and unacceptable variability at various loads. While the TENDO and PUSH showed instances of various bias, the TENDO device demonstrated greater validity when compared to the GA. Trivial-small differences were shown between the GA and TENDO during the JS and HHP exercises while trivial-moderate differences existed between GA and PUSH during the JS. However, despite trivial-small effects between the GA and PUSH devices at 20 and 40% 1RM during the HHP, practically meaningful differences existed at 60, 80, and 100%, indicating that the PUSH velocity outputs were not accurate. The TENDO appears to be more reliable and valid than the PUSH when measuring MBV and PBV during the JS and HHP.

Propulsion Phase Characteristics of Loaded Jump Variations in Resistance-Trained Women

The purpose of this study was to compare the propulsion phase characteristics of the jump squat (JS), hexagonal barbell jump (HEXJ), and jump shrug (JShrug) performed across a spectrum of relative loads. Thirteen resistance-trained women (18-23 years old) performed JS, HEXJ, and JShrug repetitions at body mass (BM) or with 20, 40, 60, 80, or 100% BM during three separate testing sessions. Propulsion mean force (MF), duration (Dur), peak power output (PP), force at PP (F_PP), and velocity at PP (V_PP) were compared between exercises and loads using a series of 3 × 6 repeated measures ANOVA and Hedge's g effect sizes. There were no significant differences in MF or Dur between exercises. While load-averaged HEXJ and JShrug PP were significantly greater than the JS, there were no significant differences between exercises at any individual load. The JShrug produced significantly greater F_PP than the JS and HEXJ at loads ranging from BM-60% BM, but not at 80 or 100% BM. Load-averaged V_PP produced during the JS and HEXJ was significantly greater than the JShrug; however, there were no significant differences between exercises at any individual load. Practically meaningful differences between exercises indicated that the JShrug produced greater magnitudes of force during shorter durations compared to the JS and HEXJ at light loads (BM-40%). The JS and HEXJ may be classified as more velocity-dominant exercises while the JShrug may be more force-dominant. Thus, it is important to consider the context in which each exercise is prescribed for resistance-trained women to provide an effective training stimulus.

Muscle Architectural and Force-Velocity Curve Adaptations following 10 Weeks of Training with Weightlifting Catching and Pulling Derivatives

The aims of this study were to examine the muscle architectural, rapid force production, and force-velocity curve adaptations following 10 weeks of resistance training with either submaximal weightlifting catching (CATCH) or pulling (PULL) derivatives or pulling derivatives with phase-specific loading (OL). 27 resistance-trained men were randomly assigned to the CATCH, PULL, or OL groups and completed pre- and post-intervention ultrasound, countermovement jump (CMJ), and isometric mid-thigh pull (IMTP). Vastus lateralis and biceps femoris muscle thickness, pennation angle, and fascicle length, CMJ force at peak power, velocity at peak power, and peak power, and IMTP peak force and force at 100-, 150-, 200-, and 250 ms were assessed. There were no significant or meaningful differences in muscle architecture measures for any group (p > 0.05). The PULL group displayed small-moderate (g = 0.25-0.81) improvements in all CMJ variables while the CATCH group displayed trivial effects (g = 0.00-0.21). In addition, the OL group displayed trivial and small effects for CMJ force (g = -0.12-0.04) and velocity variables (g = 0.32-0.46), respectively. The OL group displayed moderate (g = 0.48-0.73) improvements in all IMTP variables while to PULL group displayed small-moderate (g = 0.47-0.55) improvements. The CATCH group displayed trivial-small (g = -0.39-0.15) decreases in IMTP performance. The PULL and OL groups displayed visible shifts in their force-velocity curves; however, these changes were not significant (p > 0.05). Performing weightlifting pulling derivatives with either submaximal or phase-specific loading may enhance rapid and peak force production characteristics. Strength and conditioning practitioners should load pulling derivatives based on the goals of each specific phase, but also allow their athletes ample exposure to achieve each goal.

Comparing biomechanical time series data across countermovement shrug loads

The effect of load on time-series data has yet to be investigated during weightlifting derivatives. This study compared the effect of load on the force-time and velocity-time curves during the countermovement shrug (CMS). Twenty-nine males performed the CMS at relative loads of 40%, 60%, 80%, 100%, 120%, and 140% one repetition maximum (1RM) power clean (PC). A force plate measured the vertical ground reaction force (VGRF), which was used to calculate the barbell-lifter system velocity. Time-series data were normalized to 100% of the movement duration and assessed via statistical parametric mapping (SPM). SPM analysis showed greater negative velocity at heavier loads early in the unweighting phase (12-38% of the movement), and greater positive velocity at lower loads during the last 16% of the movement. Relative loads of 40% 1RM PC maximised propulsion velocity, whilst 140% 1RM maximized force. At higher loads, the braking and propulsive phases commence at an earlier percentage of the time-normalized movement, and the total absolute durations increase with load. It may be more appropriate to prescribe the CMS during a maximal strength mesocycle given the ability to use supramaximal loads. Future research should assess training at different loads on the effects of performance.

Comparing Biomechanical Time Series Data During the Hang-Power Clean and Jump Shrug

ABSTRACT

Kipp, K, Comfort, P, and Suchomel, TJ. Comparing biomechanical time series data during the hang-power clean and jump shrug. J Strength Cond Res 35(9): 2389-2396, 2021-The purpose of this study was to investigate differences in the force-, velocity-, displacement-, and power-time curves during the hang-power clean (HPC) and the jump shrug (JS). To this end, 15 male lacrosse players were recruited from a National Collegiate Athletic Association Division-I team, and performed one set of 3 repetitions of the HPC and JS at 70% of their HPC 1 repetition maximum (1RM HPC). Two in-ground force plates were used to measure the vertical ground reaction force (GRF) and calculate the barbell-lifter system mechanics during each exercise. The time series data were normalized to 100% of the movement phase, which included the initial countermovement and extension phases, and analyzed with curve analysis and statistical parametric mapping (SPM). The SPM procedure highlighted significant differences in the force-time curves of the HPC and JS between 85 and 100% of the movement phase. Likewise, the SPM procedure highlighted significant differences in the velocity- and power-time curve of the HPC and JS between 90 and 100% of the movement phase. For all comparisons, performance of the JS was associated with greater magnitudes of the mechanical outputs. Although results from the curve analysis showed significant differences during other periods of the movement phase, these differences likely reflect statistical issues related to the inappropriate analysis of time series data. Nonetheless, these results collectively indicate that when compared with the HPC, execution of the JS is characterized by greater GRF and barbell-lifter system velocity and power outputs during the final 10% of the movement phase.

The effect of load based on body mass percentage on peak power output in the hang power clean, hang high pull, and mid-thigh clean pull

BACKGROUND

Prescribing load at the peak power output (PPO) is one of the strategies utilized to enhance lower-body muscle power. PPO of an exercise is determined based on a relative percentage of the one-repetition maximum test (1RM). However, 1RM tests may be impractical in some weightlifting derivatives. This study aimed to identify the PPO of the hang power clean (HPC), hang high pull (HHP), and mid-thigh clean pull (MTCP) based on a relative percentage of body mass (BM).

METHODS

Fifteen males with weightlifting experience performed HPC, HHP, and MTCP at loads ranging from 30-90% BM. Kinematic data were collected through a 16-camera infrared motion capture system and processed based on a 3-dimensional lower-extremity model. Ground reaction force (GRF) data were collected from two force plates. PPO was calculated as the product of model center of mass velocity and combined vertical GRF during the concentric phase.

RESULTS

PPO occurred at 90% BM for the HPC. In addition, the PPO occurred at 90% BM for the HHP and it was not different than 70 and 80% BM. At last, the PPO for MTCP occurred at 80% BM and it was not different than 60 and 70% BM.

CONCLUSIONS

Relative percentages of BM can be used to determine PPO in the HPC, HHP, and MTCP. PPO during HPC is achieved at 90% BM, while the PPO for HHP and MTCP is achieved between 70 to 90% BM and 60 to 80% BM, respectively.

Optimal Loading for Force Production in the Straight Bar Deadlift: Force-Time Characteristics in Strength-Trained Adults

ABSTRACT

Lawson, C, Mundy, P, Lyons, M, and Duncan, MJ. Optimal loading for force production in the straight bar deadlift: Force-time characteristics in strength-trained adults. J Strength Cond Res 35(6): 1636-1641, 2021-This study sought to identify whether there is an optimum load in relation to peak force development and rate of force development (RFD) in the straight bar deadlift and to examine whether baseline strength levels influence this optimum load. Twelve strength-trained men (mean age ± SD; 25.1 ± 5.4 years) performed 3 deadlift repetitions at loads of 10% intervals of 20-90% of their predetermined individual 1 repetition maximum (1RM). Peak vertical force (PFz) and RFD were determined from each repetition. The repetition at each percentage of 1RM that produced the greatest PFz was used for analysis. All data were collected on an AMTI force platform. Repeated-measures analysis of variance indicated significant differences in PFz across loads of 20-90% 1RM (p = 0.001) with a linear increase in PFz with increasing % of 1RM. The highest PFz occurred at 90% of 1RM. For RFD, there was a significant main effect for load (p = 0.018) where instantaneous RFD was significantly higher at 80 and 90% 1RM compared with 20% 1RM. When analyses were re-run using baseline strength as a covariate, the results did not change, indicating that baseline strength did not influence the PFz or RFD output. These results suggest that there is no significant difference in RFD between adjacent loads, but that peak force production was greatest at 90% 1RM in the straight bar deadlift.

Comparison of Joint Work During Load Absorption Between Weightlifting Derivatives

ABSTRACT

Suchomel, TJ, Giordanelli, MD, Geiser, CF, and Kipp, K. Comparison of joint work during load absorption between weightlifting derivatives. J Strength Cond Res 35(2S): S127-S135, 2021-This study examined the lower-extremity joint-level load absorption characteristics of the hang power clean (HPC) and jump shrug (JS). Eleven Division I male lacrosse players were fitted with 3-dimensional reflective markers and performed 3 repetitions each of the HPC and JS at 30, 50, and 70% of their 1 repetition maximum (1RM) HPC while standing on force plates. Load absorption joint work and duration at the hip, knee, and ankle joints were compared using 3-way repeated-measures mixed analyses of variance. Cohen's d effect sizes were used to provide a measure of practical significance. The JS was characterized by greater load absorption joint work compared with the HPC performed at the hip (p < 0.001, d = 0.84), knee (p < 0.001, d = 1.85), and ankle joints (p < 0.001, d = 1.49). In addition, greater joint work was performed during the JS compared with the HPC performed at 30% (p < 0.001, d = 0.89), 50% (p < 0.001, d = 0.74), and 70% 1RM HPC (p < 0.001, d = 0.66). The JS had a longer loading duration compared with the HPC at the hip (p < 0.001, d = 0.94), knee (p = 0.001, d = 0.89), and ankle joints (p < 0.001, d = 0.99). In addition, the JS had a longer loading duration compared with the HPC performed at 30% (p < 0.001, d = 0.83), 50% (p < 0.001, d = 0.79), and 70% 1RM HPC (p < 0.001, d = 0.85). The JS required greater hip, knee, and ankle joint work on landing compared with the load absorption phase of the HPC, regardless of load. The HPC and JS possess unique load absorption characteristics; however, both exercises should be implemented based on the goals of each training phase.

Peak Power Output and Onset of Muscle Activation During High Pull Exercise

ABSTRACT

Barnes, MJ, Petterson, A, and Cochrane, DJ. Peak power output and onset of muscle activation during high pull exercise. J Strength Cond Res 35(3): 675-679, 2021-The aim of this study was to determine the percentage of 1 repetition maximum (1RM) at which peak power output occurred during the high pull (HP) exercise. In addition, the onset time of the biceps femoris (BF) and gluteus maximus (GM), across a range of loads, was investigated. Twelve resistance-trained men performed 1RM testing for the HP followed by lifts at 10% increments from 30 to 80% 1RM. During each load of power, output was measured using a linear potentiometer, whereas surface electromyography was recorded from the BF and GM. Peak power output occurred at 70% (1881.9 ± 296.1 W); however, there was no significant difference between loads at 60-80% (all p > 0.05). Loads between 40 and 80% 1RM produced significantly higher power outputs than 30% while 80% generated greater power than 100% 1RM (all p < 0.05). There was no significant (p > 0.05) main effect of muscle or load in the onset of BF (156.5-212.1 ms) or GM (112.1-158.1 ms). Therefore, these results suggest that training at a load between 60 and 80% 1RM may be useful in increasing power in the HP. In addition, activation of 2 of the hip extensors occurs in a relatively synchronous order irrespective of load.

Comparison of the Power Output Between the Hang Power Clean and Hang High Pull Across a Wide Range of Loads in Weightlifters

ABSTRACT

Takei, S, Hirayama, K, and Okada, J. Comparison of the power output between the hang power clean and hang high pull across a wide range of loads in weightlifters. J Strength Cond Res 35(2S): S84-S88, 2021-The current study compared the peak power output during the hang power clean (HPC) and hang high pull (HHP) across a wide range of external loads in weightlifters. Eight weightlifters completed 1 repetition maximum (1RM) assessment for the HPC (1.59 ± 0.17 kg/body mass) and a power test for the HPC and HHP at relative loads of 40, 60, 70, 80, 90, 95, and 100% 1RM of the HPC. The ground reaction force and 2-dimensional bar position data were recorded to determine the system (barbell + body mass) kinetics and bar height, respectively. System power was calculated as force multiplied by system velocity. The HHP produced significantly greater peak power than the HPC at 40, 60, and 70% 1RM. Conversely, there was no statistical or practical difference in peak power between the exercises at 80, 90, 95, and 100% 1RM. No significant interaction was found in force at peak power, whereas velocity at peak power was significantly greater during the HHP than during the HPC at 40, 60, and 70% 1RM. In addition, significantly greater peak bar height was observed for the HHP than the HPC at 40, 60, and 70% 1RM. From the power output comparisons across loads, the HHP should be used over the HPC at loads of 40-70% 1RM, whereas the HPC and HHP can be interchangeably used at loads of 80-100% 1RM.

A Comparison of Kinetic and Kinematic Variables During the Midthigh Pull and Countermovement Shrug, Across Loads

Meechan, D, Suchomel, TJ, McMahon, JJ, and Comfort, P. A comparison of kinetic and kinematic variables during the midthigh pull and countermovement shrug, across loads. J Strength Cond Res 34(7): 1830-1841, 2020-This study compared kinetic and kinematic variables during the midthigh pull (MTP) and countermovement shrug (CMS). Eighteen men (age: 29.43 ± 3.95 years, height: 1.77 ± 0.08 m, body mass: 84.65 ± 18.79 kg, and 1 repetition maximum [1RM] power clean: 1.02 ± 0.18 kg·kg) performed the MTP and CMS at intensities of 40, 60, 80, 100, 120, and 140% 1RM, in a progressive manner. Peak force (PF), mean force (MF), peak velocity, peak barbell velocity (BV), peak power, (PP), mean power (MP), and net impulse were calculated from force-time data during the propulsion phase. During the CMS, PF and MF were maximized at 140% 1RM and was significantly greater than the MTP at all loads (p ≤ 0.001, Hedges g = 0.66-0.90); p < 0.001, g = 0.74-0.99, respectively). Peak velocity and BV were significantly and meaningfully greater during the CMS compared with the MTP across all loads (p < 0.001, g = 1.83-2.85; p < 0.001, g = 1.73-2.30, respectively). Similarly, there was a significantly and meaningfully greater PP and MP during the CMS, across all loads, compared with the MTP (p < 0.001, g = 1.45-2.22; p < 0.001, g = 1.52-1.92). Impulse during the CMS was also significantly greater across all loads (p < 0.001, g = 1.20-1.66) compared with the MTP. Results of this study demonstrate that the CMS may be a more advantageous exercise to perform to enhance force-time characteristics when compared with the MTP, due to the greater kinetics and kinematic values observed.

A Comparison of Kinetic and Kinematic Variables During the Pull From the Knee and Hang Pull, Across Loads

Meechan, D, McMahon, JJ, Suchomel, TJ, and Comfort, P. A comparison of kinetic and kinematic variables during the pull from the knee and hang pull, across loads. J Strength Cond Res 34(7): 1819-1829, 2020-Kinetic and kinematic variables during the pull from the knee (PFK) and hang pull (HP) were compared in this study. Eighteen men (age = 29.43 ± 3.95 years; height 1.77 ± 0.08 m; body mass 84.65 ± 18.79 kg) performed the PFK and HP with 40, 60, 80, 100, 120, and 140% of 1-repetition maximum (1RM) power clean, in a progressive manner. Peak force (PF), mean force (MF), peak system velocity (PSV), mean system velocity (MSV), peak power (PP), mean power (MP), and net impulse were calculated from force-time data during the propulsion phase. During the HP, small-to-moderate yet significantly greater MF was observed compared with the PFK, across all loads (p ≤ 0.001; Hedges g = 0.47-0.73). Hang pull PSV was moderately and significantly greater at 100-140% 1RM (p = 0.001; g = 0.64-0.94), whereas MSV was significantly greater and of a large-to-very large magnitude compared with PFK, across all loads (p < 0.001; g = 1.36-2.18). Hang pull exhibited small to moderate and significantly greater (p ≤ 0.011, g = 0.44-0.78) PP at 100-140%, with moderately and significantly greater (p ≤ 0.001, g = 0.64-0.98) MP across all loads, compared with the PFK. Hang pull resulted in a small to moderate and significantly greater net impulse between 100 and 140% 1RM (p = 0.001, g = 0.36-0.66), compared with PFK. The results of this study demonstrate that compared with the PFK, the HP may be a more beneficial exercise to enhance force-time characteristics, especially at loads of ≥1RM.

Training With Weightlifting Derivatives: The Effects of Force and Velocity Overload Stimuli

Suchomel, TJ, McKeever, SM, and Comfort, P. Training with weightlifting derivatives: The effects of force and velocity overload stimuli. J Strength Cond Res 34(7): 1808-1818, 2020-The purposes of this study were to compare the training effects of weightlifting movements performed with (CATCH) or without (PULL) the catch phase of clean derivatives performed at the same relative loads or training without the catch phase using a force- and velocity-specific overload stimulus (OL) on isometric and dynamic performance tasks. Twenty-seven resistance-trained men completed 10 weeks of training as part of the CATCH, PULL, or OL group. The CATCH group trained using weightlifting catching derivatives, while the PULL and OL groups used biomechanically similar pulling derivatives. The CATCH and PULL groups were prescribed the same relative loads, while the OL group was prescribed force- and velocity-specific loading that was exercise and phase specific. Preintervention and postintervention isometric midthigh pull (IMTP), relative one repetition maximum power clean (1RM PC), 10-, 20-, and 30-m sprint, and 505 change of direction on the right (505R) and left (505L) leg were examined. Statistically significant differences in preintervention to postintervention percent change were present for relative IMTP peak force, 10-, 20-, and 30-m sprints, and 505L (all p < 0.03), but not for relative 1RM PC or 505R (p > 0.05). The OL group produced the greatest improvements in each of the examined characteristics compared with the CATCH and PULL groups with generally moderate to large practical effects being present. Using a force- and velocity-specific overload stimulus with weightlifting pulling derivatives may produce superior adaptations in relative strength, sprint speed, and change of direction compared with submaximally loaded weightlifting catching and pulling derivatives.

The Effect of Training with Weightlifting Catching or Pulling Derivatives on Squat Jump and Countermovement Jump Force-Time Adaptations

The purpose of this study was to examine the changes in squat jump (SJ) and countermovement jump (CMJ) force-time curve characteristics following 10 weeks of training with either load-matched weightlifting catching (CATCH) or pulling derivatives (PULL) or pulling derivatives that included force- and velocity-specific loading (OL). Twenty-five resistance-trained men were randomly assigned to the CATCH, PULL, or OL groups. Participants completed a 10 week, group-specific training program. SJ and CMJ height, propulsion mean force, and propulsion time were compared at baseline and after 3, 7, and 10 weeks. In addition, time-normalized SJ and CMJ force-time curves were compared between baseline and after 10 weeks. No between-group differences were present for any of the examined variables, and only trivial to small changes existed within each group. The greatest improvements in SJ and CMJ height were produced by the OL and PULL groups, respectively, while only trivial changes were present for the CATCH group. These changes were underpinned by greater propulsion forces and reduced propulsion times. The OL group displayed significantly greater relative force during the SJ and CMJ compared to the PULL and CATCH groups, respectively. Training with weightlifting pulling derivatives may produce greater vertical jump adaptations compared to training with catching derivatives.

Mechanical power production assessment during weightlifting exercises. A systematic review

The assessment of the mechanical power production is of great importance for researchers and practitioners. The purpose of this review was to compare the differences in ground reaction force (GRF), kinematic, and combined (bar velocity x GRF) methods to assess mechanical power production during weightlifting exercises. A search of electronic databases was conducted to identify all publications up to 31 May 2019. The peak power output (PPO) was selected as the key variable. The exercises included in this review were clean variations, which includes the hang power clean (HPC), power clean (PC) and clean. A total of 26 articles met the inclusion criteria with 53.9% using the GRF, 38.5% combined, and 30.8% the kinematic method. Articles were evaluated and descriptively analysed to enable comparison between methods. The three methods have inherent methodological differences in the data analysis and measurement systems, which suggests that these methods should not be used interchangeably to assess PPO in Watts during weightlifting exercises. In addition, this review provides evidence and rationale for the use of the GRF to assess power production applied to the system mass while the kinematic method may be more appropriate when looking to assess only the power applied to the barbell.

Weightlifting Overhead Pressing Derivatives: A Review of the Literature

This review examines the literature on weightlifting overhead pressing derivatives (WOPDs) and provides information regarding historical, technical, kinetic and kinematic mechanisms as well as potential benefits and guidelines to implement the use of WOPDs as training tools for sports populations. Only 13 articles were found in a search of electronic databases, which was employed to gather empirical evidence to provide an insight into the kinetic and kinematic mechanisms underpinning WOPDs. Practitioners may implement WOPDs such as push press, push jerk or split jerk from the back as well as the front rack position to provide an adequate stimulus to improve not only weightlifting performance but also sports performance as: (1) the use of WOPDs is an additional strategy to improve weightlifting performance; (2) WOPDs require the ability to develop high forces rapidly by an impulsive triple extension of the hips, knees and ankles, which is mechanically similar to many sporting tasks; (3) WOPDs may be beneficial for enhancing power development and maximal strength in the sport population; and, finally, (4) WOPDs may provide a variation in training stimulus for the sports population due to the technical demands, need for balance and coordination. The potential benefits highlighted in the literature provide a justification for the implementation of WOPDs in sports training. However, there is a lack of information regarding the longitudinal training effects that may result from implementing WOPDs.

Is the Optimal Load for Maximal Power Output During Hang Power Cleans Submaximal?

PURPOSE

The optimal load for maximal power output during hang power cleans (HPCs) from a mechanical perspective is the 1-repetition-maximum (1RM) load; however, previous research has reported otherwise. The present study thus aimed to investigate the underlying factors that determine optimal load during HPCs.

METHODS

Eight competitive Olympic weight lifters performed HPCs at 40%, 60%, 70%, 80%, 90%, 95%, and 100% of their 1RM while the ground-reaction force and bar/body kinematics were simultaneously recorded. The success criterion during HPC was set above parallel squat at the receiving position.

RESULTS

Both peak power and relative peak power were maximized at 80% 1RM (3975.7 [439.1] W, 50.4 [6.6] W/kg, respectively). Peak force, force at peak power, and relative values tended to increase with heavier loads (P < .001), while peak system velocity and system velocity at peak power decreased significantly above 80% 1RM (P = .005 and .011, respectively). There were also significant decreases in peak bar velocity (P < .001) and bar displacement (P < .001) toward heavier loads. There was a strong positive correlation between peak bar velocity and bar displacement in 7 of 8 subjects (r > .90, P < .01). The knee joint angle at the receiving position fell below the quarter-squat position above 70% 1RM.

CONCLUSIONS

Submaximal loads were indeed optimal for maximal power output for HPC when the success criterion was set above the parallel-squat position. However, when the success criterion was defined as the quarter-squat position, the optimal load became the 1RM load.

Effect of Onset Threshold on Kinetic and Kinematic Variables of a Weightlifting Derivative Containing a First and Second Pull

James, LP, Suchomel, TJ, McMahon, JJ, Chavda, S, and Comfort, P. Effect of onset threshold on kinetic and kinematic variables of a weightlifting derivative containing a first and second pull. J Strength Cond Res 34(2): 298-307, 2020-This study sought to determine the effect of different movement onset thresholds on both the reliability and absolute values of performance variables during a weightlifting derivative containing both a first and second pull. Fourteen men (age: 25.21 ± 4.14 years; body mass: 81.1 ± 11.4 kg; and 1 repetition maximum [1RM] power clean: 1.0 ± 0.2 kg·kg) participated in this study. Subjects performed the snatch-grip pull with 70% of their power clean 1RM, commencing from the mid-shank, while isolated on a force platform. Two trials were performed enabling within-session reliability of dependent variables to be determined. Three onset methods were used to identify the initiation of the lift (5% above system weight [SW], the first sample above SW, or 10 N above SW), from which a series of variables were extracted. The first peak phase peak force and all second peak phase kinetic variables were unaffected by the method of determining movement onset; however, several remaining second peak phase variables were significantly different between methods. First peak phase peak force and average force achieved excellent reliability regardless of the onset method used (coefficient of variation [CV] < 5%; intraclass correlation coefficient [ICC] > 0.90). Similarly, during the second peak phase, peak force, average force, and peak velocity achieved either excellent or acceptable reliability (CV < 10%; ICC > 0.80) in all 3 onset conditions. The reliability was generally reduced to unacceptable levels at the first sample and 10 N method across all first peak measures except peak force. When analyzing a weightlifting derivative containing both a first and second pull, the 5% method is recommended as the preferred option of those investigated.

The Effect of Load Placement on the Power Production Characteristics of Three Lower Extremity Jumping Exercises

The purpose of this study was to compare the power production characteristics of the jump squat (JS), hexagonal barbell jump (HEXJ), and jump shrug (JShrug) across a spectrum of relative loads. Fifteen resistance-trained men completed three testing sessions where they performed repetitions of either the JS, HEXJ, or JShrug at body mass (BM) or with 20, 40, 60, 80, or 100% of their BM. Relative peak power (PPRel), relative force at PP (FPP), and velocity at PP (VPP) were compared between exercises and loads. In addition, power-time curves at each load were compared between exercises. Load-averaged HEXJ and JShrug PPRel were statistically greater than the JS (both p < 0.01), while no difference existed between the HEXJ and the JShrug (p = 1.000). Load-averaged JShrug FPP was statistically greater than both the JS and the HEXJ (both p < 0.001), while no statistical difference existed between the JS and the HEXJ (p = 0.111). Load-averaged JS and HEXJ VPP were statistically greater than the JShrug (both p < 0.01). In addition, HEXJ VPP was statistically greater than the JS (p = 0.009). PPRel was maximized at 40, 40, and 20% BM for the JS, HEXJ, and JShrug, respectively. The JShrug possessed statistically different power-time characteristics compared to both the JS and the HEXJ during the countermovement and propulsion phases. The HEXJ and the JShrug appear to be superior exercises for PPRel compared to the JS. The HEXJ may be considered a more velocity-dominant exercise, while the JShrug may be a more force-dominant one.

Effect of Accommodating Elastic Bands on Mechanical Power Output during Back Squats

The aim of this study was to investigate whether accommodating elastic bands with barbell back squats (BSQ) increase muscular force during the deceleration subphase. Ten healthy men (mean ± standard deviation: Age: 23 ± 2 years; height: 170.5 ± 3.7 cm; mass: 66.7 ± 5.4 kg; and BSQ one repetition maximum (RM): 105 ± 23.1 kg; BSQ 1RM/body mass: 1.6 ± 0.3) were recruited for this study. The subjects performed band-resisted parallel BSQ (accommodating elastic bands each sides of barbell) with five band conditions in random order. The duration of the deceleration subphase, mean mechanical power, and the force and velocity during the acceleration and deceleration subphases were calculated. BSQ with elastic bands elicited greater mechanical power output, velocity, and force during the deceleration subphase, in contrast to that elicited with traditional free weight (p < 0.05). BSQ with elastic bands also elicited greater mechanical power output and velocity during the acceleration subphase. However, the force output during the acceleration subphase using an elastic band was lesser than that using a traditional free weight (p < 0.05). This study suggests that BSQ with elastic band elicit greater power output during the acceleration and deceleration subphases.

The Importance of Muscular Strength: Training Considerations

This review covers underlying physiological characteristics and training considerations that may affect muscular strength including improving maximal force expression and time-limited force expression. Strength is underpinned by a combination of morphological and neural factors including muscle cross-sectional area and architecture, musculotendinous stiffness, motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition. Although single- and multi-targeted block periodization models may produce the greatest strength-power benefits, concepts within each model must be considered within the limitations of the sport, athletes, and schedules. Bilateral training, eccentric training and accentuated eccentric loading, and variable resistance training may produce the greatest comprehensive strength adaptations. Bodyweight exercise, isolation exercises, plyometric exercise, unilateral exercise, and kettlebell training may be limited in their potential to improve maximal strength but are still relevant to strength development by challenging time-limited force expression and differentially challenging motor demands. Training to failure may not be necessary to improve maximum muscular strength and is likely not necessary for maximum gains in strength. Indeed, programming that combines heavy and light loads may improve strength and underpin other strength-power characteristics. Multiple sets appear to produce superior training benefits compared to single sets; however, an athlete's training status and the dose-response relationship must be considered. While 2- to 5-min interset rest intervals may produce the greatest strength-power benefits, rest interval length may vary based an athlete's training age, fiber type, and genetics. Weaker athletes should focus on developing strength before emphasizing power-type training. Stronger athletes may begin to emphasize power-type training while maintaining/improving their strength. Future research should investigate how best to implement accentuated eccentric loading and variable resistance training and examine how initial strength affects an athlete's ability to improve their performance following various training methods.

An Investigation Into the Effects of Excluding the Catch Phase of the Power Clean on Force-Time Characteristics During Isometric and Dynamic Tasks: An Intervention Study

Comfort, P, Dos'Santos, T, Thomas, C, McMahon, JJ, and Suchomel, TJ. An investigation into the effects of excluding the catch phase of the power clean on force-time characteristics during isometric and dynamic tasks: an intervention study. J Strength Cond Res 32(8): 2116-2129, 2018-The aims of this study were to compare the effects of the exclusion or inclusion of the catch phase during power clean (PC) derivatives on force-time characteristics during isometric and dynamic tasks, after two 4-week mesocycles of resistance training. Two strength matched groups completed the twice-weekly training sessions either including the catch phase of the PC derivatives (Catch group: n = 16; age 19.3 ± 2.1 years; height 1.79 ± 0.08 m; body mass 71.14 ± 11.79 kg; PC 1 repetition maximum [1RM] 0.93 ± 0.15 kg·kg) or excluding the catch phase (Pull group: n = 18; age 19.8 ± 2.5 years; height 1.73 ± 0.10 m; body mass 66.43 ± 10.13 kg; PC 1RM 0.91 ± 0.18 kg·kg). The Catch and Pull groups both demonstrated significant (p ≤ 0.007, power ≥0.834) and meaningful improvements in countermovement jump height (10.8 ± 12.3%, 5.2 ± 9.2%), isometric mid-thigh pull performance (force [F]100: 14.9 ± 17.2%, 15.5 ± 16.0%, F150: 16.0 ± 17.6%, 16.2 ± 18.4%, F200: 15.8 ± 17.6%, 17.9 ± 18.3%, F250: 10.0 ± 16.1%,10.9 ± 14.4%, peak force: 13.7 ± 18.7%, 9.7 ± 16.3%), and PC 1RM (9.5 ± 6.2%, 8.4 ± 6.1%), before and after intervention, respectively. In contrast to the hypotheses, there were no meaningful or significant differences in the percentage change for any variables between groups. This study clearly demonstrates that neither the inclusion nor exclusion of the catch phase of the PC derivatives results in any preferential adaptations over two 4-week, in-season strength and power, mesocycles.

Force-Time Differences between Ballistic and Non-Ballistic Half-Squats

The purpose of this study was to examine the force-time differences between concentric-only half-squats (COHS) performed with ballistic (BAL) or non-ballistic (NBAL) intent across a range of loads. Eighteen resistance-trained men performed either BAL or NBAL COHS at 30%, 50%, 70%, and 90% of their one repetition maximum (1RM) COHS. Relative peak force (PF) and relative impulse from 0–50 ms (Imp50), 0–90 ms (Imp90), 0–200 ms (Imp200), and 0–250 ms (Imp250) were compared using a series of 2 × 4 (intent × load) repeated measures ANOVAs with Bonferroni post hoc tests. Cohen’s d effect sizes were calculated to provide measures of practical significance between the BAL and NBAL COHS and each load. BAL COHS produced statistically greater PF than NBAL COHS at 30% (d = 3.37), 50% (d = 2.88), 70% (d = 2.29), and 90% 1RM (d = 1.19) (all p < 0.001). Statistically significant main effect differences were found between load-averaged BAL and NBAL COHS for Imp90 (p = 0.006, d = 0.25), Imp200 (p = 0.001, d = 0.36), and Imp250 (p < 0.001, d = 0.41), but not for Imp50 (p = 0.018, d = 0.21). Considering the greater PF and impulse observed during the BAL condition, performing COHS with BAL intent may provide a favorable training stimulus compared to COHS performed with NBAL intent.

Mechanical Demands of the Hang Power Clean and Jump Shrug: A Joint-Level Perspective

Kipp, K, Malloy, PJ, Smith, J, Giordanelli, MD, Kiely, MT, Geiser, CF, and Suchomel, TJ. Mechanical demands of the hang power clean and jump shrug: a joint-level perspective. J Strength Cond Res 32(2): 466-474, 2018-The purpose of this study was to investigate the joint- and load-dependent changes in the mechanical demands of the lower extremity joints during the hang power clean (HPC) and the jump shrug (JS). Fifteen male lacrosse players were recruited from a National Collegiate Athletic Association DI team, and completed 3 sets of the HPC and JS at 30, 50, and 70% of their HPC 1 repetition maximum (1RM HPC) in a counterbalanced and randomized order. Motion analysis and force plate technology were used to calculate the positive work, propulsive phase duration, and peak concentric power at the hip, knee, and ankle joints. Separate 3-way analysis of variances were used to determine the interaction and main effects of joint, load, and lift type on the 3 dependent variables. The results indicated that the mechanics during the HPC and JS exhibit joint-, load-, and lift-dependent behavior. When averaged across joints, the positive work during both lifts increased progressively with external load, but was greater during the JS at 30 and 50% of 1RM HPC than during the HPC. The JS was also characterized by greater hip and knee work when averaged across loads. The joint-averaged propulsive phase duration was lower at 30% than at 50 and 70% of 1RM HPC for both lifts. Furthermore, the load-averaged propulsive phase duration was greater for the hip than the knee and ankle joint. The joint-averaged peak concentric power was the greatest at 70% of 1RM for the HPC and at 30%-50% of 1RM for the JS. In addition, the joint-averaged peak concentric power of the JS was greater than that of the HPC. Furthermore, the load-averaged peak knee and ankle concentric joint powers were greater during the execution of the JS than the HPC. However, the load-averaged power of all joints differed only during the HPC, but was similar between the hip and knee joints for the JS. Collectively, these results indicate that compared with the HPC the JS is characterized by greater hip and knee positive joint work, and greater knee and ankle peak concentric joint power, especially if performed at 30 and 50% of 1RM HPC. This study provides important novel information about the mechanical demands of 2 commonly used exercises and should be considered in the design of resistance training programs that aim to improve the explosiveness of the lower extremity joints.

Effects of weightlifting exercise, traditional resistance and plyometric training on countermovement jump performance: a meta-analysis

Jump performance is considered an important factor in many sports. Thus, strategies such as weightlifting (WL) exercises, traditional resistance training (TRT) and plyometric training (PT) are effective at improving jump performance. However, it is not entirely clear which of these strategies can enable greater improvements on jump height. Thus, the purpose of the meta-analysis was to compare the improvements on countermovement jump (CMJ) performance between training methods which focus on WL exercises, TRT, and PT. Seven studies were included, of which one study performed both comparison. Therefore, four studies comparing WL exercises vs. TRT (total n = 78) and four studies comparing WL exercises vs. PT (total n = 76). The results showed greater improvements on CMJ performance for WL exercises compared to TRT (ES_diff: 0.72 ± 0.23; _95%CI: 0.26, 1.19; P = 0.002; Δ % = 7.5 and 2.1, respectively). The comparison between WL exercises vs. PT revealed no significant difference between protocols (ES_diff: 0.15 ± 0.23; _95%CI: -0.30, 0.60; P = 0.518; Δ % = 8.8 and 8.1, respectively). In conclusion, WL exercises are superior to promote positive changes on CMJ performance compared to TRT; however, WL exercises and PT are equally effective at improving CMJ performance.

Effects of Load on Peak Power Output Fatigue During the Bench Throw

Boffey, D, Sokmen, B, Sollanek, K, Boda, W, and Winter, S. Effects of load on peak power output fatigue during the bench throw. J Strength Cond Res 33(2): 355-359, 2019-The ability to create power is an important variable for athletic success. No study to date has compared peak power output (PPO) fatigue across multiple sets and with different loads with the bench throw. This study aimed to begin the process of establishing empirical upper-body power training guidelines for moderately strong athletes by determining how load (30, 45, and 60% 1 repetition maximum [1RM]) affects PPO (Watts) dropoff during 3 sets of 10 repetitions of the bench throw. Ten resistance-trained male volunteers ([mean ± SD]: age 20.58 ± 1.36 years, height 176.05 ± 9.09 cm, body mass 78.65 ± 9.93 kg, bench press 1RM 99.79 ± 18.52 kg) performed 3 sets of 10 repetitions of the bench throw with one of the 3 loads during 3 weekly sessions. A Humac 360 device collected concentric phase PPO data during each repetition. The data were analyzed using one-way (treatment) and 2-way (treatment × time) repeated-measures analysis of variance. A significant decrease in PPO was observed during repetitions 5-7 at 30%, 3-4 at 45%, and 2-3 at 60% 1RM. Based on the results of this study, coaches who want to maximize power should potentially keep sets of upper-body plyometrics within these repetition ranges. The authors recommend that moderately strong athletes perform the bench throw on a Smith machine at 45% or 60% 1RM to produce high PPO over multiple sets.

Kinetic and kinematic patterns during high intensity clean movement: searching for optimal load

The aim of the present study was to investigate loading effects on kinematic and kinetic variables among elite-weightlifters in order to identify an optimal training load to maximize power production for clean-movement. Nine elite-weightlifter (age: 24 ± 4years, body-mass: 77 ± 6.5kg, height: 176 ± 6.1cm and 1RM clean: 170 ± 5kg) performed 2 separate repetitions of the clean using 85, 90, 95% and 100%, in a randomized order, while standing on a force platform and being recorded using 3D-capture-system. Differences in kinematics (barbell displacement, velocity and acceleration) and kinetics (power, vertical ground reaction force (vGRF), rate of force development (RFD), and work) across the loads were statistically assessed. Results revealed significant load effects for the majority of the studied parameters (p < 0.01) and showed that typical bar-displacement, greatest bar-velocity and peak-power were achieved at 85 and 90% 1RM (p < 0.001). Additionally greater average power was shown for 90 and 95% (p < 0.01) and greater work and vGRF were shown for 90, 95 and 100% than 85% 1RM (p < 0.05). Load had no significant effect on peak-vGRF and peak-RFD (p > 0.05). The results of this study, suggest 90% 1RM to be the most advantageous load to train explosive-force and to enhance power-outputs while maintaining technical efficiency in elite-weightlifters.

The Importance of Muscular Strength in Athletic Performance

This review discusses previous literature that has examined the influence of muscular strength on various factors associated with athletic performance and the benefits of achieving greater muscular strength. Greater muscular strength is strongly associated with improved force-time characteristics that contribute to an athlete's overall performance. Much research supports the notion that greater muscular strength can enhance the ability to perform general sport skills such as jumping, sprinting, and change of direction tasks. Further research indicates that stronger athletes produce superior performances during sport specific tasks. Greater muscular strength allows an individual to potentiate earlier and to a greater extent, but also decreases the risk of injury. Sport scientists and practitioners may monitor an individual's strength characteristics using isometric, dynamic, and reactive strength tests and variables. Relative strength may be classified into strength deficit, strength association, or strength reserve phases. The phase an individual falls into may directly affect their level of performance or training emphasis. Based on the extant literature, it appears that there may be no substitute for greater muscular strength when it comes to improving an individual's performance across a wide range of both general and sport specific skills while simultaneously reducing their risk of injury when performing these skills. Therefore, sport scientists and practitioners should implement long-term training strategies that promote the greatest muscular strength within the required context of each sport/event. Future research should examine how force-time characteristics, general and specific sport skills, potentiation ability, and injury rates change as individuals transition from certain standards or the suggested phases of strength to another.

The Optimal Load for Maximal Power Production During Lower-Body Resistance Exercises: A Meta-Analysis

BACKGROUND

The development of muscular power is often a key focus of sports performance enhancement programs.

OBJECTIVE

The purpose of this meta-analysis was to examine the effect of load on peak power during the squat, jump squat, power clean, and hang power clean, thus integrating the findings of various studies to provide the strength and conditioning professional with more reliable evidence upon which to base their program design.

METHODS

A search of electronic databases [MEDLINE (SPORTDiscus), PubMed, Google Scholar, and Web of Science] was conducted to identify all publications up to 30 June 2014. Hedges' g (95% confidence interval) was estimated using a weighted random-effect model. A total of 27 studies with 468 subjects and 5766 effect sizes met the inclusion criterion and were included in the statistical analyses. Load in each study was labeled as one of three intensity zones: Zone 1 represented an average intensity ranging from 0 to 30% of one repetition maximum (1RM); Zone 2 between 30 and 70% of 1RM; and Zone 3 ≥70% of 1RM.

RESULTS

These results showed different optimal loads for each exercise examined. Moderate loads (from >30 to <70% of 1RM) appear to provide the optimal load for power production in the squat exercise. Lighter loads (≤30% of 1RM) showed the highest peak power production in the jump squat. Heavier loads (≥70% of 1RM) resulted in greater peak power production in the power clean and hang power clean.

CONCLUSION

Our meta-analysis of results from the published literature provides evidence for exercise-specific optimal loads for power production.

Weightlifting pulling derivatives: rationale for implementation and application

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.

Effect of various loads on the force-time characteristics of the hang high pull

The purpose of this study was to investigate the effect of various loads on the force-time characteristics associated with peak power during the hang high pull (HHP). Fourteen athletic men (age: 21.6 ± 1.3 years; height: 179.3 ± 5.6 cm; body mass: 81.5 ± 8.7 kg; 1 repetition maximum [1RM] hang power clean [HPC]: 104.9 ± 15.1 kg) performed sets of the HHP at 30, 45, 65, and 80% of their 1RM HPC. Peak force, peak velocity, peak power, force at peak power, and velocity at peak power were compared between loads. Statistical differences in peak force (p = 0.001), peak velocity (p < 0.001), peak power (p = 0.015), force at peak power (p < 0.001), and velocity at peak power (p < 0.001) existed, with the greatest values for each variable occurring at 80, 30, 45, 80, and 30% 1RM HPC, respectively. Effect sizes between loads indicated that larger differences in velocity at peak power existed as compared with those displayed by force at peak power. It seems that differences in velocity may contribute to a greater extent to differences in peak power production as compared with force during the HHP. Further investigation of both force and velocity at peak power during weightlifting variations is necessary to provide insight on the contributing factors of power production. Specific load ranges should be prescribed to optimally train the variables associated with power development during the HHP.

Examination of a lumbar spine biomechanical model for assessing axial compression, shear, and bending moment using selected Olympic lifts

BACKGROUND/AIMS

Loading during concurrent bending and compression associated with deadlift, hang clean and hang snatch lifts carries the potential for injury to the intervertebral discs, muscles and ligaments. This study examined the capacity of a newly developed spinal model to compute shear and compressive forces, and bending moments in lumbar spine for each lift.

METHODS

Five male subjects participated in the study. The spine was modeled as a chain of rigid bodies (vertebrae) connected via the intervertebral discs. Each vertebral reference frame was centered in the center of mass of the vertebral body, and its principal directions were axial, anterior-posterior, and medial-lateral.

RESULTS

The results demonstrated the capacity of this spinal model to assess forces and bending moments at and about the lumbar vertebrae by showing the variations among these variables with different lifting techniques.

CONCLUSION

These results show the model's potential as a diagnostic tool.