What Forces Act On A Person During A Power Clean

Introduction

The ability to produce concentric vertical power is a operation-determining variable in many sports and plays an of import role in performance event. Although vertical ability production is enhanced through repetition of relevant contest sporting movements (^3–5), virtually elite training programs supplement with resistance-based modalities. Of the resistance training modalities shown to develop concentric vertical power production, the weightlifting movements are criterion within most aristocracy environments. This is evidenced past 88% of National Football League (¹⁶), 100% of National Hockey League (¹⁷), and 95% of National Basketball Association (⁵¹) strength and conditioning coaches surveyed reporting the utilization of the weightlifting movements in the training of their athletes.

The weightlifting movements are used in elite training environments every bit they have been robustly reported to correspond with loftier power production capabilities and to direct increase vertical power production. Garhammer (²²) reported meridian power production in elite weightlifters between 1,853 and iv,807 W for snatch and 2,206 and four,758 W for clean across weight classes, whereas Carlock et al. (^viii) reported correlations between 0.90 and 0.93 associating peak power during vertical jumping and the weightlifting contest movements in national and international quotient male weightlifters. Training investigations by Tricoli et al. (⁵⁴) and Hawkins et al. (³⁰) using subjects of unclear training histories and Hoffman et al. (³¹) using trained sub-aristocracy athletes each reported a direct benefit of weightlifting training on vertical ability product. Although these works provide insight into the relationship between weightlifting training and vertical power production, there is still a paucity of literature systematically detailing these effects on naive aristocracy populations and the associated changes in movement technique.

Although it is acknowledged that weightlifting training develops vertical power production, teaching these lifts may not actually be a worthwhile endeavor in the forcefulness and workout setting because the significant fourth dimension involvement (^14,xv,39) necessary to reach a minimal level of proficiency and initial benefit (^24,47,49,55). This reported limitation may have the largest impact in aristocracy grooming environments where the demands of maximizing sporting functioning exceed the resource of the athlete. Considering there may exist more areas of specific sporting mastery than can be effectively trained, elite-level coaches may be particularly weary of investing the time and athlete resources necessary to finer implement weightlifting preparation.

Even though weightlifting training has been robustly demonstrated to increase vertical power product, it cannot be accounted a worthwhile forcefulness and conditioning preparation modality for elite athlete populations until the initial time investment necessary to attain a power benefit is understood. Thus, the purpose of this investigation was to establish and systematically document the learning investment necessary to benefit vertical power product during the squat bound (SJ) and countermovement leap (CMJ) with weightlifting learning in elite athletes from a naive state. Additionally, this investigation tracked the associated kinematic changes in weightlifting technique over the course of the learning procedure to document technical flaws in naive elite athletes and changes with learning experience. To best empathise the time investment interaction in the elite athlete preparation surroundings, particularly during an Olympic preparation, a unmarried-subject research pattern was employed.

Methods

Experimental Approach to the Problem

This investigation used a unmarried-subject time series design of 4 international quotient athletes naive to weightlifting (³⁴). Over the course of the investigation period (maximum of 169 days), athletes regularly attended two hang ability clean (HPC) learning sessions every 7 days in addition to their regular sport-specific preparation. Monitoring of leap performance occurred approximately every 28 days during the first 110 days of the learning process using measurement of kinetic data from SJ and CMJ. Kinematic monitoring of the learning progression occurred approximately every 28 days commencing after the 34th day of learning and connected through the learning process. Hang power clean learning was performed as the first exercise after the warm-upwardly during twice weekly gym sessions and preceded by classic free-weight exercises for the lower body, including back squat, front squat, lunge, step-up, and Romanian deadlift (RDL). A single low- to medium-level plyometric (e.thou., jump rope, low lateral hops) exercise was introduced to the programme on an individual basis after the 64th solar day from baseline; withal, volumes were kept low and the exercise used was familiar from training history. All other weighted and unweighted jump exercises historically used in the training of these athletes were omitted from the plan during the investigation period. All HPC learning sessions were taught direct via one-to-one instruction by the first author (holding qualifications with NSCA CSCS, USAW level i, and four+ years of experience instructing and programming the weightlifting movements to National Collegiate Athletic Clan Division I and Olympic-level athletes). Didactics progression used a "part-whole" and "top-down" arroyo as suggested in mutual coaching literature (^14,15,33,39). Briefly, each athlete began with a basic group of exercises (e.thousand., shrug, jump shrug) and progressed to greater complication movements only when accounted good; yet, earlier progressions were revisited throughout the learning menstruum based on individual need. Initial teaching sessions for the kickoff fourteen–28 days were time based with xx–30 minutes per gym session allocated to HPC learning. Then, based on individual athlete technical progression, duration-based sessions yielded to formalized training consisting of planned volumes, relative intensities, and residual periods. The number of total repetitions and rest periods per session were determined by the investigator and based primarily on the load and movement design used with earlier progressions involving bar work permitting the highest volume of repetitions and later progressions nether greater loading permitting the fewest repetitions (all in a periodized manner). As athlete movement proficiency progressed with preparation experience, the load used was determined in consultation between athlete and investigator. The master loading emphasis was a relative intensity sufficient to create a grooming stimulus, only non so intense every bit to cause premature fatigue or technical breakdown with subsequent repetitions.

Subjects

Athletes (n = iv) were members of the Australian National Short Rail Speed Skating Squad and were registered members of the Australian Olympic Shadow team with each voluntarily participating in the investigation. Each athlete had previous feel with free-weight resistance grooming consisting predominantly of multi-joint lower-trunk forcefulness exercises, including squat variations, deadlifts, and lunge variations. However, all athletes were naive to the weightlifting movements (i.e., snatch, clean, jerk) and their variations (due east.g., clean pull). Athletes' concrete characteristics, sexual activity, age, weight, height, short rails feel, and resistance training experience, are shown in Table 1. Athletes were betwixt the ages of 17 and 22 years at the get-go of the investigation. No parameters of on-ice functioning were kept during the investigation menstruum as regular time trials were not part of training in this phase of their periodized programme and supplemental testing was not possible during an Olympic flavour. Informed consent was obtained from each participant or from participant and parent or guardian if under the age of xviii years. The Australian Constitute of Sport and the Charles Sturt University Homo Research Ethics Committees both approved this investigation.

Tabular array 1:

Athlete characteristics at baseline before beginning the hang power clean learning process.

Monitoring Parameters

Hang power make clean monitoring commenced on the 35th day equally the athletes were naive and thus incapable of producing an HPC movement pattern at baseline (24-hour interval 0). During HPC monitoring, athletes performed 3 sets of two–3 repetitions filmed from the sagittal aeroplane (GoPro Hero4; GoPro, San Mateo, CA, United states) at 120 Hz with a minimum of 3 minutes balance between sets. Field of study to athlete grooming status, testing sets employed 75–90% loads of an estimated i repetition maximum (1RM). The following HPC kinematic variables were identified from each testing occasion: hip, knee, and ankle articulation angles at get-go concentric phase HPC (Get-go); hip, knee, ankle joint angles, and shin bending vs. vertical at peak genu flexion of double knee joint bend HPC (TRANSITION); hip, knee, and ankle joint angles at completion of second pull (PEAK EXT); torso angle vs. horizon at the last rack position (Take hold of); peak vertical displacement of right ankle as an indicator of vertical torso mass displacement (Ankle PVD); maximal horizontal displacement of barbell anterior to metatarsal-phalangeal joint (BB MAX Hd); and qualitative analysis of the concentric bar path trace.

All joint angle trackings were performed and analyzed with Kinovea version 7.1 (Kinovea.org, open source); bar path tracking was performed with Dartfish TeamPro (Dartfish; Fribourg, Switzerland) and analyzed with Image J software (National Institutes of Health, Bethesda, Medico, USA). For a given frame, a measurement scale was set with a known distance of the weightlifting plate visible in frame. To compare changes in concentric sagittal plane bar path over time, a digital trace of the second repetition'southward bar path from a set using a load between 75 and 85% estimated 1RM HPC set at each time point was determined. To decide BB MAX Hard disk, a vertical reference line was placed at the metatarsal-phalangeal joint from the start position and peak horizontal distance between reference line and barbell trace recorded.

To provide insight into kinetic changes accompanying HPC learning process, vertical SJ and CMJ measurements were recorded via a linear position transducer (GymAware; Kinetic Functioning, Mitchell, Australia). To examine how the HPC learning procedure afflicted CMJ stop range of move (ROM) strategy, forcefulness product at toe off, changes in the timing of elevation velocity, and the decrease in velocity from peak to toe off were determined at each testing occasion via force plate (FT 400; Fettle Technologies, Skye, Australia). Vertical jump testing commenced at baseline (day 0), and on each testing occasion, athletes get-go performed i set up of four SJ and and so a single set of 4 CMJ repetitions with no added resistance (all at torso weight). All jumps were performed with a bar of minimal mass (0.ii kg) placed on the shoulders in a loftier barbell squat position. A minimal pause separated each jump repetition as each athlete returned themselves to the initial starting position and reset to perform the next repetition with each set of SJ and CMJ separated past a minimum of 8 minutes. The variables monitored for both SJ and CMJ were as follows: peak vertical power, pinnacle vertical velocity, peak vertical displacement, difference betwixt peak velocity and velocity at toe off, and elapsed time betwixt peak velocity and toe off. Although the athletes performed no additional resistance-based power training over the class of the investigation, they did perform on-ice dart protocols in conjunction with dryland skating–specific endurance vertical bound protocols approximately i–ii times every 7 days as part of their regular training. All on-ice dart and dry-state jump protocols had been performed in a like manner past each athlete for a minimum of 3 years.

Statistical Analyses

Hang ability make clean data are reported as mean ± SD of all within-testing session repetitions. Vertical jump data are reported every bit mean ± SD of all within-testing session repetitions for either SJ or CMJ. Typical error of measurement for CMJ has been reported as 0.02 1000 (⁵⁷), whereas the typical error of measurement across all joint angles was 1.77° and 0.016 m for distances.

Results

The hateful number of sessions attended past each athlete was 26.00 ± 5.89 resulting in 494 ± 157.89 HPC repetitions completed. Each athlete missed a 20-day menstruum of specific HPC training because of an international on-ice training army camp where HPC training was deemed inconsistent with the periodized program. Nonetheless, HPC 3RM improved lx–lxx% for each athlete over the course of the investigation.

Learning Progression Vertical Leap Kinetic Changes

The Squat Spring Performance

At baseline (24-hour interval 0), the athletes produced 4,452.78 ± 216.83, 2,814.xiii ± 445.75, 3,957.49 ± 271.83, and 5,772.46 ± 644.38 W pinnacle power (athletes A–D, respectively). Past the get-go jump testing occasion (24-hour interval 34), peak power increased 14.ane–35.seven% in all athletes, with similar positive changes observed for peak velocity (3.4–13.4%) and peak vertical displacement (3.vii–20.0%) (Effigy ane). This tendency continued through the third testing occasion (athlete D: day 64; athletes A–C: solar day 83) equally all athletes demonstrated increases in peak power, velocity, and vertical displacement (Figure 1). Beyond all 4 jump testing occasions (athlete D: 84 days; athletes A and B: 109 days; athlete C: 116 days), all athletes demonstrated improved peak ability (xiv.1–35.7%) and peak velocity (3.four–13.4%); however, only 3 of iv athletes exhibited an increment in peak vertical displacement (5.6–xx.0%) with the fourth athlete observed no change (Figure 1).

Figure 1:

Changes in squat leap kinetic variables with hang power make clean learning over the four testing occasions for athletes A (circle), B (square), C (triangle), and D (diamond). Each information bespeak represents the mean ± SD of 4 trials for each athlete.

The Countermovement Spring Operation

Athletes at baseline produced 4,437.57 ± 313.21, 3,363.93 ± 231.eleven, four,589.93 ± 686.25, and five,773.81 ± 363.83 West peak ability (athletes A–D, respectively). By the first jump testing occasion, elevation power increased for three of four athletes; pinnacle velocity and peak displacement increased for 2 of 4 athletes (Effigy 2). By the third testing occasion, ii of iv athletes demonstrated increases in height ability and peak velocity; peak displacement increased for 3 of 4 athletes (Figure two). Across all 4 spring testing occasions, 3 of 4 athletes demonstrated increases in elevation power and peak displacement; two of 4 athletes demonstrated increases in peak velocity (Figure ii).

Figure 2:

Changes in countermovement jump kinetic variables with hang ability make clean learning over the 4 testing occasions for athletes A (circle), B (square), C (triangle), and D (diamond). Each data bespeak represents the hateful ± SD of 4 trials for each athlete.

Difference in Vertical Velocities Between Acme and Toe Off

Two of 4 athletes recorded a reduction in the difference between peak and toe off vertical velocities (athlete A: 38.24%; athlete B: 25.64%; athlete C: −31.03%; athlete D: −38.46%) across all four bound testing occasions (Effigy 3). Of the 2 athletes exhibiting this trend, athlete C decreased on 3 of the 4 testing occasions (24-hour interval 0: 0.58 ± 0.07 k·southward⁻¹; twenty-four hours 34: 0.47 ± 0.12 g·due south⁻¹; twenty-four hours 83: 0.53 ± 0.07 m·south⁻ⁱ; 24-hour interval 115: 0.40 ± 0.04 thousand·south⁻¹) and athlete D decreased on each occasion (day 0: 0.52 ± 0.06 thousand·southward^−ane; day 34: 0.51 ± 0.06 m·south⁻¹; day 64: 0.48 ± 0.11 m·s⁻¹; day 83: 0.32 ± 0.04 m·south⁻¹).

Figure 3:

Changes in end range of motion countermovement jump kinetics: divergence between peak and toe off velocities (filled shape); timing of peak velocity relative to toe off (open shape) with hang power clean learning over the 4 testing occasions for athletes A (circle), B (square), C (triangle), and D (diamond). Each information bespeak represents the mean ± SD of 4 trials for each athlete.

Timing of Peak Velocity

Changes in the elapsed time betwixt peak velocity and toe off (Figure iii) indicate that athletes C and D had substantial fourth dimension reductions across all 4 jump testing occasions (athlete A: 17.lx%; athlete B: viii.47%; athlete C: −17.76%; athlete D: −23.08%). Interestingly, athlete C demonstrated a decrease on 3 testing occasions (24-hour interval 0: 61 ± 4 ms, Mean solar day 34: 53 ± 8 ms; Day 83: 59 ± ix ms; Solar day 115: 50 ± 4 ms), whereas athlete D demonstrated a reduction on each occasion (Day 0: 52 ± v ms, Mean solar day 34: 50 ± 4 ms; Day 64: 48 ± 7 s; Twenty-four hour period 83: xl ± 0 ms).

Learning Progression Kinematic Changes

The changes in kinematic variables during HPC learning for each athlete are summarized in Figures 4–8.

Figure iv:

Changes in kinematic variables and sagittal plane bar path trace over the four testing occasions for athlete A. Vertical reference line is fatigued from right metatarsal-phalangeal joint at commencement position; difference from this line in the finish position indicates the athlete has moved forward or backward during the take hold of stage. Information collection ceased when the bar reached summit vertical displacement afterward the catch. Values correspond mean (SD) of 6–nine trials for the individual athlete.

Figure 5:

Changes in kinematic variables and sagittal airplane bar path trace over the 4 testing occasions for athlete B. Vertical reference line is drawn from right metatarsal-phalangeal joint at get-go position; deviation from this line in the terminate position indicates the athlete has moved forwards or backward during the catch phase. Data collection ceased when the bar reached meridian vertical displacement after the catch. Values represent mean (SD) of 6–ix trials for the individual athlete.

Effigy 6:

Changes in kinematic variables and sagittal plane bar path trace over the 4 testing occasions for athlete C. Vertical reference line is drawn from right metatarsal-phalangeal joint at offset position; departure from this line in the finish position indicates the athlete has moved forward or backward during the catch phase. Data collection ceased when the bar reached peak vertical displacement after the catch. Values represent mean (SD) of 6–9 trials for the individual athlete.

Figure seven:

Changes in kinematic variables and sagittal plane bar path trace over the 4 testing occasions for athlete D. Vertical reference line is drawn from right metatarsal-phalangeal articulation at outset position; deviation from this line in the finish position indicates the athlete has moved forward or backward during the catch phase. Data collection ceased when the bar reached elevation vertical displacement after the catch. Values represent mean (SD) of 6–9 trials for the individual athlete.

Effigy 8:

Changes in (A) ANKLE PVD and (B) BB Hard disk drive MAX for each athlete over the four testing occasions for athletes A (circle), B (square), C (triangle), and D (diamond). Each data point represents the mean ± SD of half-dozen–9 trials for each athlete. X axis short tick marks betoken days from baseline of 62, 124, and 163.

Offset

Across HPC kinematic testing (athlete A: 129 days; athlete B: 90 days; athlete C: 136 days; athlete D: 92 days), 3 of 4 athletes increased their talocrural joint joint angle at the START position (athlete A: 17.30%; athlete B: 6.78%; athlete C: −0.76%; athlete D: vi.45%). This trend was axiomatic by the 2nd testing occasion with all 4 athletes demonstrating increment (twenty-four hour period: 62–77; athlete A: 0.39%; athlete B: half-dozen.fifteen%; athlete C: 2.77%; athlete D: 4.88%).

TRANSITION

All athletes decreased the shin bending vs. perpendicular (athlete A: −34.24%; athlete B: −28.84%; athlete C: −43.90%; athlete D: −21.37%) and increased peak knee flexion (athlete A: 4.86%; athlete B: vii.27%; athlete C: 17.35%; athlete D: 2.60%) across HPC kinematic testing in the TRANSITION position. This trend was axiomatic for both variables by the second testing occasion for all 4 athletes (athletes A and B: day 62; athlete D: day 64; athlete C: solar day 77). The magnitude of reduction in shin angle vs. perpendicular at this fourth dimension ranged betwixt −5.69 and −xiii.80% across the 4 athletes. However, simply three of 4 athletes at the second testing occasion were observed to accept increased peak knee flexion (athlete A: −iii.53%; athlete B: iv.47%; athlete C: four.93%; athlete D: 0.53%).

PEAK EXT

Three of 4 athletes decreased plantar flexion (athlete A: −11.66%; athlete B: 6.43%; athlete C: −5.79%; athlete D: −x.00%) during HPC learning with this tendency observed in ii of iv athletes past the second occasion (athlete A: −one.24%; athlete B: 3.85%; athlete C: −0.01%; athlete D: 3.42%). At peak extension, the decrease in plantar flexion was observed to occur in isolation of changes in other kinematic variables as no visible design of alter was evident at the hip or knee joint for the involved athletes.

Take hold of

All athletes reduced their body angle at Take hold of across HPC kinematic testing; notwithstanding, the decrease in all athletes was not observable by the second testing occasion (athlete A: ane.00%; athlete B: iii.38%; athlete C: 2.34%; athlete D: 9.02%).

Ankle PVD

At the initial HPC kinematic testing occasion (day 34), the athletes exhibited a range of peak ankle vertical deportation with greatest displacement recorded past athlete A (day 34: 16.87 ± 1.09 cm) and the smallest initial displacement past athlete B (day 34: 5.73 ± 0.76 cm). In dissimilarity, past the completion of the formal learning process (athlete B: day 124; athlete D: solar day 126; athlete A: day 163; athlete C: day 170), all athletes exhibited similar peak ankle vertical displacements ranging betwixt half-dozen.51 ± 0.60 cm (athlete B) and 8.49 ± 0.86 cm (athlete D).

BB MAX HD

3 of 4 athletes decreased (athlete A: 4.05%; athlete B: −78.65%; athlete C: −41.04%; athlete D: −37.13%) across all 4 HPC kinematic testing occasions with this tendency emergent past the second testing occasion (athlete A: 1.51%; athlete B: −12.75%; athlete C: −27.50%; athlete D: −20.32%).

Discussion

A key finding of this investigation is weightlifting training–benefited vertical power production in all 4 elite athletes within the first 35 days of learning from a naive state with continued furnishings for 84–116 days. This is evident from increased SJ peak power both at the second jump testing occasion (9.two–32.half-dozen% increase) and across all 4 jump testing occasions (fourteen.1–35.7% increment) for all 4 athletes (Figure i). Accompanying changes in CMJ power product, 2 athletes demonstrated changes in finish ROM force application through clear trends toward amend timing of top velocity and a decreased velocity differential between peak and toe off (Figure 3) across all jump testing occasions. Accompanying increases in power production were changes in technique exhibited across all stages of the HPC for each athlete. Although previous works have demonstrated the benefits of training with weightlifting techniques on vertical jump performance (^30,31,54), this is the first to specifically use an elite group of athletes and the first to report changes in vertical ability production simultaneously with technical skill acquisition. Furthermore, this is the first investigation to track changes in motility kinematics under practical loading atmospheric condition and the showtime longitudinal investigation. In improver to improvements in vertical power product, nosotros observed consequent kinematic (technique) changes in athletes' functioning of the HPC. A learning theme common to the 4 athletes was changes in kinematics suggesting barbell center of mass shifted to a position more over the base of support and a more efficient utilization of hip extension to drive vertical power production. This is apparent from increases in ankle angle at START, smaller shin angles vs. perpendicular at TRANSITION (Figures iv–7), and the minimization of BB MAX HD (Effigy 8B) across all 4 HPC kinematic testing occasions. When considered together, these adjustments provide evidence of a posterior-directed shift in center of pressure (COP) throughout the concentric stage of HPC and the possibility of a corresponding increase in utilization of the hip extensors to bulldoze vertical barbell velocity (^xix). We also demonstrate a shift with increased expertise toward decreased plantar flexion at Summit EXT (Figures 4–vii). A further important finding is the shift toward minimal merely real ANKLE PVD with HPC learning (Figure 8A). Importantly, all these technical changes were observed during HPC operation under loads of 75–90% 1RM (estimated), providing substantiative prove under conditions experienced in practical training environments (^46,53). Nosotros believe that the underpinnings of these shifts are multifactorial with the need to maximize impulse, limit the amount of ground reaction strength directed at moving trunk mass, and perform a ballistic-intentioned move all playing a function.

A major finding of this investigation is HPC learning from a naive country yielded benefits to vertical power production within the initial 4 weeks of learning for 4 elite curt track speed skating athletes. This is the first investigation to our knowledge that systematically documents the time frame to initial power do good with weightlifting learning in aristocracy athletes. These changes are verified through gains by all athletes in all parameters of SJ (pinnacle ability, superlative velocity, peak displacement) and gains in CMJ tiptop ability experienced by three of 4 athletes by twenty-four hour period 34. Although the HPC may be a more technical movement pattern than other power evolution modalities like plyometric and weighted jumps (^11,13,47,55), information technology was capable of producing benefit within like time frames for our athletes (^xi,12). Considering the long-term demonstrated benefit of weightlifting training on vertical power product in combination with the apartment learning bend reported in this investigation, we consider weightlifting training to be a worthwhile power development tool for these aristocracy athletes.

In add-on to the novel curt-term benefits documented, the results of our investigation support continued benefits on vertical ability product with three of 4 athletes demonstrating gains in elevation power and meridian velocity for SJ betwixt the final 2 jump testing occasions. Although information technology is possible that the 125- to 171-day flow was budgeted a performance plateau, the insufficiently technical nature of the weightlifting movements suggests much longer time frames to staleness of stimulus. Although all 4 athletes in this investigation were elite and quickly grasped the HPC movement design, no athlete approached the attainment of technical mastery at study completion. The notion of multiyear time frames to exhibit mastery of the weightlifting movements is supported in the literature (^2,37,55), though we would debate that mastery is not necessary to utilise HPC to better vertical power production every bit observed by the SJ and CMJ performances of these athletes (Figures 1 and 2). Considering HPC technical development can be partially defined as improved ability production efficiency, improvement in technical parameters is likely to be associated with further ability gains.

Although athletes C and D failed to demonstrate substantial changes in CMJ peak vertical displacement with HPC learning, both however demonstrated shifts in force application strategy. This is the offset investigation to report direct changes in stop ROM jump kinetics with weightlifting preparation. Changes were evident from increases in vertical velocity at toe off relative to top vertical velocity and the timing of meridian vertical velocity closer to toe off with HPC learning (Figure iii). This trend is important every bit the performance outcome (i.e., peak displacement) is determined entirely by vertical velocity in combination with elevation of middle of mass at toe off (^9,38). Thus, the minimization of velocity loss between summit and toe off, potentially resulting from the timing of peak closer to toe off, should maximize pinnacle vertical deportation. Nosotros hypothesize that trained weightlifters will tend to produce vertical velocity values at toe off closer to peak velocity than elite jumping athletes naive to the lifts and weightlifters achieve this through deceleration of the hip and knee joints later in the ROM; however, this is however to exist systematically confirmed. This hypothesis is supported past modeling work reported by Pandy et al. (⁴³), who determined that the theoretical maximization of displacement requires the complete absence of articulation deceleration during ground contact as a ways to maximize impulse. Strategies completely void of deceleration may not be practical considering of the need to protect joint integrity (^one); however, weightlifting preparation may function to improve vertical power production by delaying the timing of deceleration.

As suggested in coaching literature (^{14,23,27,36,44,45,47}) and confirmed through kinematic assay performed with aristocracy weightlifters (^28,29,32), proficiency in the above-knee HPC commencement position is characterized past a mid- to rear-directed COP, with the shoulders "covering the bar" as viewed from the sagittal plane. Hip (^42,48,55) and ankle (^42,47,48) angles tend to arroyo a right angle, and knee joint angles tend to exist obtuse and betwixt 145° and 155° (^35,47,55). All athletes in this investigation showed an intuition for the start position at baseline, which we attribute to preexisting familiarity with the RDL. Despite understanding the initial get-go position, athletes even so demonstrated kinematic changes over the grade of the investigation with differences almost the ankle being the most consistent and notable (Figures four–7). Increases in Kickoff ankle angle with learning were observed in athletes A, B, and D, indicating a shift toward a mid to rear-based COP, which is expected when compared with elite weightlifter kinematic analyses (^{20,23,27,47,55}). An appropriate rearward shift keeps the bar in a more than biomechanically efficient position as the knees navigate the bar and may allow for a more efficient utilization of hip extension over the class of the transition and second pull. Hip and knee start kinematics besides showed alter in athletes B, C, and D, but a greater variation in the pattern of change betwixt athletes was observed (Figures 4–7). We propose that this between-athlete variation occurs as each athlete moves from a basic conceptual agreement of the general HPC movement pattern to a more specialized motor pattern specific to their individual genetics. Once a full general movement framework is understood, the kinesthetic feedback provided past the hundreds of HPC repetitions performed affords each athlete an opportunity to understand optimal hip and knee positions for their individual articulation leverages and technical mode. An private outcome every bit optimal is supported by the between-athlete differences reported in hip and articulatio genus joint angles within elite weightlifting populations (^47,48,55), suggesting that a specific value or combination of values is not a criterion.

Similar to Offset, best evidence suggests TRANSITION (position of maximal knee flexion) is characterized past a mid- to ball of foot–directed COP (^27,47,55) and a shoulder position that continues to comprehend the bar, although to a bottom extent (^23,47,48). In comparison with Commencement, proficient TRANSITION is marked by relatively greater hip angles and bottom knee and ankle angles (^47,48,55), which is intuitive considering the repositioning of the knees to a more flexed position (^18,27) and forcefulness developed through hip extension (⁵⁵) every bit the barbell passes the lower thigh. It was observed that over time, all athletes exhibited an increase in knee flexion during TRANSITION (Figures iv–vii). Enoka (¹⁸), and later supported by Garhammer and Taylor (²⁷), reported that the knee extensors play a pivotal role in driving ability production during the second pull of the clean. Thus, knee extension–based power production over a greater ROM is an intuitive progression for novice athletes. Although the results of this investigation lend support, this hypothesis must be considered in context, as the knee does not work in isolation during the transition phase or the second pull. Novice athletes may underuse knee ROM during the 2nd pull (Figures 4–seven) because of an disability to effectively bulldoze vertical barbell velocity through hip extension while simultaneously repositioning the knees to an optimal position. Information technology is this balance betwixt effective hip extension and simultaneous knee joint flexion that deems the transition phase of the HPC the toughest to primary during weightlifting pulls (^fifty,52).

The descriptive results of this study indicate improvements in transition stage mechanics as evidenced past changes in talocrural joint and shin angles at TRANSITION with all athletes demonstrating a more vertical shin angle at TRANSITION and athletes A, B, and C meantime showing greater ankle angles. These changes provide for a more than vertical shank position and corresponding mid- to ball of foot–directed COP (¹⁹). This positioning allows non only a more efficient utilization of hip extension during the transition stage (^7,55) but too the continuous employ of hip extension to drive ability in combination with the knee and ankle extensors during the subsequent second pull (⁴⁷). The purpose of the HPC transition is to produce vertical barbell velocity through hip extension while simultaneously setting the hips and knees in a position to maximize further power contribution during the subsequent second pull. The more mid-directed COP with HPC learning and the increased knee joint flexion at TRANSITION support the concept of transition mechanics moving in a direction of greater efficiency for these iv athletes.

Criterion angles for each articulation at Top EXT accept non been established and are hotly debated in both weightlifting and strength and conditioning circles with some coaches advocating full "triple extension" (^{6,21,33,44,45}) and others preferring more than acute angles across some or all lower-body joints (^{28,29,32,47,48}). Although the benefits of maximizing impulse would support triple extension as the criterion, various analyses with elite weightlifters tend to disbelieve the maximization of plantar flexion (^27,28,47) in adept HPC mechanics. The observations of this investigation clearly dispute the efficacy of triple extension at the ankle articulation with all athletes progressing toward a tendency of submaximal plantar flexion at PEAK EXT despite being instructed to employ maximal talocrural joint extension during HPC execution (Figures 4–7). Although athletes A, C, and D trended toward decreased plantar flexion with HPC learning and the fourth athlete toward increased plantar flexion, all finished the investigation within a similar range of submaximal values (124.78 ± two.33° to 136.l ± ii.88°).

Our reported observation of submaximal plantar flexion with HPC learning in conjunction with aristocracy weightlifter analyses (^29,47,49) suggests submaximal plantar flexion equally necessary to maximize the kinematic links during HPC. Although advocating ankle joint utilization over a fuller ROM is intuitive because the reliance of force production on impulse, this model does non consider lower-body biomechanics as a system. Thus, it is possible that usage of the ankle joint over its cease ROM may come at the expense of effective hip extension. An optimal HPC strategy requires power production through hip extension (^47,49,55), which may just be possible when the COP is more mid-foot directed through the transition and into the second pull. Under this strategy, the COP still shifts toward the tarsals during the 2nd pull; however, it may not permit a consummate distal shift thus limiting plantar flexion.

There is a paucity of literature detailing articulation-specific angles at CATCH; even so, technically skilful weightlifters have been reported to demonstrate more acute angles than do less adept weightlifters (^47,55). Skillful CATCH may be an indicator of right sequencing and utilization of the lower-body musculature over the preceding second pull with aggressive just inefficient utilization of the hip resulting in larger Grab angles. The naive athletes in this investigation demonstrated proficient Catch angles (Figures 4–7). The ability to perform a good Grab in a relatively short learning period may bespeak a more than intuitive understanding of adept hip mechanics and lower-body sequencing over the grade of the second pull. It is possible that this intuition is the same trait that allows elite skaters to efficiently acquire technical short track skills from a naive state. Alternatively, it could exist a learned skill exhibiting directly transfer from the bound training used past these athletes as the clean is known to exist a vertical bound practical to a barbell (²⁵).

Ankle PVD equally a measure of center of mass deportation is a source of contention in weightlifting and forcefulness and conditioning circles with some coaches advocating minimal values and others preferring continuous contact or naught displacement (^47,55). The argument for continuous contact is to ensure true maximal time to apply vertical force and the minimization of vertical body mass displacement; all the same, this coaching theory may not consider the link between maximal power product and ballistic movement patterns. The ANKLE PVD is used as an indicator of athlete vertical center of mass displacement during HPC with technically skilful weightlifters tending to demonstrate smaller vertical ankle deportation values than less proficient weightlifters (^47,49). Minimizing vertical center of mass displacement may be an important factor in HPC efficiency equally it creates longer times of contact between the lifter and the platform potentially aiding impulse (⁴⁹) and because a greater percentage of vertical power production is directed at moving the mass of the bar as opposed to mass of the bar and the lifter (²⁶). Our observational data support minimal, only non absent, Ankle PVD values every bit the criterion measure of HPC efficiency as this movement pattern provides the benefits of extended contact time and approaching minimal body mass vertical deportation assuasive the kinematic links to maximize ability product through the given ROM. Although 3 athletes in this investigation demonstrated a consequent trend with learning toward smaller ANKLE PVD values, the fourth athlete remained relatively the same with all athletes finishing in a similar range of small, but non absent-minded, peak vertical displacements (vi.51 ± 0.60 to 8.24 ± 0.69 cm; Figure 8A). When gravitation toward a minimal ANKLE PVD value with HPC learning is considered in conjunction with gains in vertical spring parameters and HPC training maximums, it appears possible that a minimal, but nowadays, level of Talocrural joint PVD is necessary to maximize HPC efficiency via a ballistic motor pattern. Based on the analyses of bench press and squat motions (^{10,xiii,40,56}), greater vertical ability product is possible when ballistic versions of the movement are used (e.thousand., bench throw vs. bench press). Thus, ballistic movements via changes in neural strategies permit for agonist contribution over a greater ROM and decreased adversary inhibition as compared with the nonballistic analogue (^13,twoscore). Considering, it is probable that maximal vertical power product during HPC must be associated with a pseudoballistic motor pattern. Nosotros propose that during performance of HPC, the lifter aims to redirect the potential large displacements of body mass as ballistic ability production into the bar; yet, for the kinematic links of the body to office ballistically, a minimal level of deportation may still be necessary.

The findings of this investigation point a consistent trend for our elite athletes from novice toward adept weightlifter mechanics as summarized by changes in bar path trace and BB MAX Hard disk drive with HPC learning. Although the athletes in this investigation demonstrated differences in HPC intuition at baseline, all exhibited common initial beginner tendencies and trends in technical improvement with learning. By learning completion, each athlete demonstrated a more posterior sagittal plane barbell starting position, steeper bar path traces during the transition phase, and reduced BB MAX HD compared with baseline (Figures 4–vii, 8B). These changes may exist important as they straight the barbell center of mass more over the base of support thus limiting torque requirements (⁴¹) and because they create biomechanical positions allowing for more efficient utilization of the relevant musculature. In many regards, the sagittal barbell trace may be viewed as an indicator of kinematic movement proficiency. As all our athletes demonstrate, with learning, not merely did the barbell remain closer to the base of support over the grade of HPC, but also the initial concentric movement of the barbell tended to exist more vertically directed (i.east., steeper movement slope initiating concentric phase). This may suggest increased utilization of hip extension to drive vertical power production over the transition stage as opposed to only knee joint extension in accord with the previously discussed variables in this investigation.

In summary, training with the HPC-benefited ability production in these 4 elite short runway speed skaters within the commencement 4 weeks, which despite the greater technical complexity attributed to HPC, is a comparable time frame with other power training modalities. Preparation with the HPC also continued to benefit vertical power production, with these athletes continuing to experience gains between the final 2 leap testing occasions. Considering that none of the athletes exhibited HPC mastery past investigation completion, connected benefits of HPC training on power production are possible. With HPC training, 2 out of 4 athletes demonstrated changes in forcefulness application strategy over the end ROM with both athletes achieving height vertical velocity closer to toe off and exhibiting less decrease in velocity betwixt tiptop and toe off with learning. These changes may demonstrate a mechanism by which HPC improves vertical power production. Despite different levels of intuition pertaining to HPC mechanics, all athletes demonstrated common technical inefficiencies at baseline and trends in HPC kinematics with learning. These inefficiencies were primarily related to execution of the transition phase and probably caused past a lack of innate programming and motility skill for proper double knee curve mechanics, although other potential factors cannot exist discounted. With learning, all athletes trended toward more rearward-directed COPs during the transition phase and summit double knee bend position indicating a more efficient utilization of hip extension to affect vertical barbell power production. The athletes of this investigation did not trend toward triple extension through the ankle with learning as all moved toward submaximal plantar flexion values. This may exist attributed to a potential need to maximize vertical ability production through hip extension, with the hip and talocrural joint extensors potentially incapable of simultaneous efficient power product. Furthermore, the athletes trended toward minimal, but existent, levels of acme vertical ankle displacement with grooming. This may be acquired by the need for vertical displacement to arroyo zero to minimize the percentage of power production directed at moving body mass and to maximize the potential for impulse. Nonetheless, a minimal displacement must exist to benefit from greater impulse and power product associated with ballistic movements. In summary, HPC learning from a naive country was worthwhile for our aristocracy athletes as they experienced benefits in vertical power production within the first four weeks of learning despite previous experience with other power training modalities. Furthermore, although our athletes demonstrated different levels of HPC intuition at baseline, common technical inefficiencies were noted as were movement trends over the course of learning.

Applied Applications

These findings provide substantial supporting show for the use of weightlifting grooming within the elite forcefulness and workout environment. Although previous works have demonstrated the benefits of weightlifting preparation on vertical ability production, the amount of time investment necessary to reach a benefit was previously unknown. Considering these 4 athletes achieved substantial benefit within the start 4 weeks of learning, qualified coaches may consider removing the learning time investment as a deterrent from teaching the lifts. Additionally, coaches may consider recognizing the following beginner technical flaws and teaching the associated technical points to their elite athletes naive to the lifts: (a) a center to more than rearward-directed COP throughout the concentric phase allowing more effective utilization of hip extension; (b) the intention to plantar flex maximally with respective production of submaximal values also potentially indicating more than constructive utilization of hip extension; and (c) minimal, only real, vertical displacement of the athlete heart of mass indicating maximization of ground contact time, effective transfer of vertical power production into the barbell, and a corresponding ballistic intention.

Acknowledgments

We would like to give thanks Coach Julian Jones for his insight on study design and the weightlifting skill acquisition procedure, Dr. Derek Panchuk for his insight on skill acquisition, and Dr. Jeffrey McBride for his insight on kinematic data assay.

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Keywords:

Olympic weightlifting; skill acquisition

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