The aim of the present study was to investigate the effect of a seven-week strength training intervention using either the power clean exercise or loaded hex bar jump in enhancing performance in counter movement jump (CMJ), sprint, 505 change of direction (COD), power clean and loaded hex bar jump. Twenty-two U17 elite soccer athletes (height=182.5±5.1 cm, body mass=70±5.2 kg) underwent a seven-week strength training intervention with performance tests before and after. The athletes were randomly divided into a hex bar training group (HX) (N = 11) or a power clean group training (PC) (N = 11). They all completed three familiarization sessions before the pre-test. The first test day consisted of the loaded hex bar jump test, power clean one repetition maximum (1RM) and CMJ, while day two consisted of sprint and COD. From pre-test to post-test, CMJ (p<0.001), power clean 1RM (p<0.01), and power output for loaded hex bar jump (p<0.05) were significantly increased for both the HX and PC group. A decrease in 10-meter sprint time (p=0.02) from pre-test to posttest was found for the PC group. An unpaired t-test revealed no significant differences in any of the physical performance measures between groups at either the pre-test or the post-test. In conclusion, power clean and loaded hex bar jump training were equally effective in enhancing physical performance.

• Jump squat

• Olympic lift exercise

• Soccer players

• Elite athletes

Svane S, Thusholt M, Lerche M, Kristiansen M (2024) The Effect of a Seven-Week Strength Training Intervention Using Either Power Clean or Loaded Hex Bar Jump for Enhancing Physical Performance. Ann Sports Med Res 11(1): 1225

Maximal- and explosive strength are important physical attributes for elite athletes to be successful in their respective sport [1,2]. An increase in maximal and explosive strength of the lower limbs may cause a concomitant increase in key physical performance parameters such as sprint speed, the ability to rapidly change the direction of movement and jumping abilities [3-6]. Recent studies have found that elite soccer players possess higher levels of maximal and explosive strength compared to amateur soccer players [7,8]. And similarly, previous research has found a significantly faster sprint time [9,10], change of direction time (COD) [6] and jumping ability [6,11]. for elite sport athletes when maximal- and explosive strength levels were increased through heavy strength- and plyometric training. In this regard, the Olympic weightlifting exercises and their derivatives such as the power clean, clean pull, hang clean, power snatch, snatch pull and hang snatch are frequently used exercises in strength training for sports used to enhance power output [12,13].

The power clean exercise is often performed with a higher intensity compared to loaded plyometric training exercises such as squat jumps. This will lead to a higher power output for power clean [14]. However, the power clean exercise is often performed using a lower load compared to heavy strength training, but at a higher velocity compared to traditional heavy strength training which will also lead to a higher power output based on the force velocity relationship [14,15]. Strength training sessions including the power clean exercise has previously led to increased physical performance in team sports athletes, due to the enhanced power output [16]. Furthermore, the power clean is training the triple extension of the ankle, knee, and hip joints which transfers to performance in sprint, change of direction and jumping [6,11,17]. Furthermore, the power clean has been revealed to be superior compared to heavy resistance training in enhancing sprinting, change of direction and jumping abilities in athletes [6,11,17].

Despite the many positive things associated with the power clean, it should also be mentioned that this exercise is complex and technically demanding compared to other similar exercises with a similar movement pattern. For instance, the hex bar jump exercise also involves triple extension of the ankle, knee, and hip joint and can be loaded [18,19]. To master the power clean exercise the athlete will need expert advice and a lot of technical guidance [20]. The athlete will also need to have high flexibility in the wrist, elbow, and shoulder to get the barbell in the optimal position during the catch phase. Furthermore, the high movement velocity of the barbell make it very difficult to coordinate the lift and catch it correctly. Lastly, lack of technical skill may lead to a higher force contribution of the upper body muscles instead of the lower body muscles [20]. Within this context, it is anecdotally reported from the strength training environment and the authors of the present study, that it may take up to several years to master this exercise and enable athletes to train with an optimal intensity and volume.

An alternative exercise, which is less technically demanding while still training the same movement pattern as the power clean is the loaded hex bar jump. This exercise is presumably easier to learn, can be loaded to the optimal intensity faster due to the low technical demand, and may generate the same or even higher power output than the power clean exercise [21,19].

The existing literature comparing the Olympic weightlifting exercises to plyometric training with exercises such as loaded hex bar jump and CMJ is scarce and shows conflicting results. A study by Helland et al. [20], found plyometric to be superior in enhancing jumping ability, COD, and linear sprint speed [20], while Kaabi et al. [20], found weightlifting derivatives as the best solution for enhancing these attributes [17]. Other studies found no differences between using loaded jumps or weightlifting for enhancing physical performance in jumping ability, COD, and linear sprint speed [11,19,22]. It seems that the existing literature lacks studies investigating the differences between easier and less technically demanding exercises compared to Olympic lifts derivatives [19]. And to the best of the authors knowledge no previous research has compared strength training interventions using a loaded hex bar jump compared to the power clean exercise in enhancing vertical jump height, sprint speed and change of direction for elite youth soccer players.

Therefore, the aim of the present study was to investigate the effect of a seven-week strength training intervention using either the power clean exercise or loaded hex bar jump in enhancing performance in CMJ, 30 m sprint, 505 change of direction (COD), power clean and loaded hex bar jump. We hypothesized that training using the loaded hex bar jump exercise would not result in significant differences in terms of performance improvement in CMJ, sprint, or COD compared to training using the power clean exercise.

Experimental approach

This study used a randomized intervention design to examine various performance parameters after a seven week exercise intervention using either the power clean or loaded hex bar jumps [Figure 1]. Athletes from Aalborg soccer academy U17 were divided into two groups, of which one group performed power clean at the start of all their strength training sessions, and the other group performed loaded hex bar jumps instead. The study was conducted from the middle to the end of the 2022- 2023 season [Figure 1].

Figure 1: Shows the experimental process of the study.

Subjects

The athletes who took part in this experiment were U17 elite soccer players. Data was collected of 22 soccer athletes (height=182.4±5.0cm, body mass=70±5.1kg). All athletes had completed a minimum of five days of soccer training sessions per week and at least two resistance-training sessions per week in the last year. The athletes were divided into two groups, of which one group performed power clean (PC) (N=11) at the start of their training session, and the other group performed loaded hex bar jumps (HX) (N=11). The groups were stratified on the basis of the results from the pretest to create homogenous groups. All athletes had to have been injury free two months prior to the start of the study. The parental or guardian signed informed consent was obtained for all the athletes. The study conformed to the principles of the World Medical Association’s Declaration of Helsinki.

Procedures

Before the pre-test all athletes completed three familiarization sessions, where the goal was to learn the basic execution of the power clean, and the loaded hex bar jump exercises in order to minimize any learning effect. In the pre- and posttest, athletes performed six different performance tests, carried out on two separate days. On the first test day, body mass and height were recorded for each athlete. After the anthropometric measurements the athletes had to go through a preparatory warm-up consisting of a three-minute run and a three-minute dynamic stretching routine focusing on the ankles, knees and hips and lastly the respective test exercises with the barbell and hex bar without any additional load. Next, the performance tests were carried out in a randomized order with one third of the athletes starting with CMJ, one third starting with loaded hex bar jumps and lastly, one third starting with the 1RM power clean exercise. On the second day the athletes went through a preparatory warm-up starting with a five-minute run, followed by a five-minute dynamic stretching routine of the ankles, knees, hips and shoulders. Lastly, two trial runs with one of them being a submaximal run with 90% of maximal intensity were performed. Athletes performed the sprint and change of direction test in a randomized order with one half starting with the sprint test and the second half starting with the 505 changes of direction test. The tests were carried out in the same way for pre- and posttests. During the intervention the athletes performed strength training twice weekly, soccer practice five times weekly, and played one to two soccer matches per week.

Familiarization

The familiarization protocol consisted of three separate familiarization sessions. These sessions consisted firstly of learning the technique of the power clean, and lastly the hex bar jump. Due to the athlete’s former experience and the high reliability found in recent literature on CMJ, linear sprint and COD no further familiarization was performed in these exercises [10,21]. The familiarization of the power clean exercise was instructed and progressively learned through five exercises. The first exercise was a stretching exercise, where the participant stood in a squat position under an immovable barbell, where the elbows were turned up and inwards. When the elbows were in position, they were asked to push the barbell up, until a stretch in the elbows was felt and then hold this stretch for three seconds. The second exercise was an elbow rotation exercise, where the participant was standing with a barbell in front of them with relaxed arms. The participants were asked to bring up the barbell and rotate the elbows like in a similar hang power clean movement with a focus on the hook grip. The third exercise was a traditional hang power clean where the participants pushed the barbell up, with the use of the hip, while leaning back with a shrug and lastly rotating the elbows as practiced in the second exercise. The focus of the exercise was to learn to generate power with the hips and to avoid performing a horizontal push of the barbell the participants were asked to lean back with a shrug, so the force of the barbell would be generated in a vertical pathway. The fourth exercise was a power clean starting from the knees, where the participant focused on switching foot position. This means that they moved the feet slightly out at the same time as they went from standing on the toes to grabbing the barbell on the whole foot. The fifth and last exercise was a traditional power clean from the floor. This exercise was to practice the power clean from a full range of motion, with focus on overall technique, with multiple repetitions. At the last familiarization session, the participants were instructed in the loaded hex bar jump. Participants were told to focus on landing with a slight bend in their knees and to hold their core tightened throughout the exercise. Furthermore, they were told to not bend their back, and look straight forward throughout the trial.

Tests

The tests were separated into two different days at both pre- and posttest and separated by 48 hours. Furthermore, each test day was performed a minimum of 24 hours after normal soccer practice. All subjects completed all tests at both the pre- and post- test.

For testing the 1RM in power clean, the athletes started with a load consisting of 30 kg. The load was then increased by adding 2.5, 5 or 10 kg depending on the estimated 1RM of each athlete until failure with a rest period between sets of more than 1.5 minutes. Two additional trials were attempted at the failure load.

If the athletes succeeded an additional load of 2.5 kg was then added and repeated until three continuously failed trials were found. After each failed attempt a two-minute rest period was held. The same protocol was used at the posttest.

For testing in the loaded hex bar jump, two submaximal jumps were performed at 60 and 80% of intended maximal force with an unloaded hex bar (approximately 21kg), before the official loaded hex bar jump test began. The test began with participants standing in an upright position holding the hex bar. The jump was then initiated with an eccentric phase, followed by acceleration during the concentric phase. All athletes were told to jump as high as possible, land with a slight bend in their knees, and to stand upright at the end of every trial. They performed one trial with one repetition at each load. The trials were performed with increasing load after every repetition. The first trial was a 21 kg hex bar jump, the second trial consisted of 41 kg, third trial consisted of 61 kg and fourth trial consisted of 81 kg. A linear encoder (ChronoJump, Boscosystems, Spain) was attached to the hex bar for the sets on 61 kg and 81 kg with a rest period between 3 and 5 minutes.

For CMJ testing, two submaximal jumps were performed before the official CMJ test began. Firstly, the athletes were shown the right technique of the CMJ, then they all got the same introduction to the test where athletes were asked to place their hands on their hips and keep them there throughout the test. Then they were asked to kneel as far and as fast as they individually preferred, all the time with a focus on jumping as high as possible. Finally, they were made aware that it was not allowed to bend their knees during the flight time to extend the flight time. The athletes performed two trials of the test with one-minute rest intervals. A contact mat (ChronoJump, Boscosystems, Spain) was used to record take-off and landing times for subsequent computation of the jump height.

For sprint testing, the test was performed in an indoor hall and the athletes started with performing a warmup sprint at 90% of max effort [Figure 2]. Witty Photocells (Microgate, Italy) were set at five- 10-, 25- and 30-meter distances. The athletes performed two test runs and were told not to slow down their run prematurely. All athletes had a rest period between three and five minutes between each run. All photocells stood at a height of approximately 80 cm [Figure 2].

Figure 2: Illustrates the five-, 10-, 25-, and 30-meter (m) linear sprint test using time gates.

The athlete performed the 505 change of direction test at an indoor court (Figure 3). The test consisted of running 15 meters, then turning 180 degrees and running back to the starting point. A handheld camera was placed next to the test setup and recorded the test from start to end. All the athletes performed two trials with three-minute rest intervals between trials. The duration recorded for the distance covering five meters beyond the 10-meter point and returning to the 10-meter mark was utilized for additional analysis [Figure 3].

Figure 3: Illustrates how the 505 change of direction test was performed.

Training intervention

The training intervention consisted of seven weeks of supervised training in either power clean or loaded hex bar jump. The training was conducted twice a week performing either power clean or loaded hex bar jumps followed by their normal strength training routine without any further exercises for the lower body. The only difference between the training performed by the two groups were if they performed the power clean or the loaded hex bar jump. Throughout the intervention the training intensity increased week by week. 5 sets were performed at every session with either three (weeks 1-4) or two repetitions (weeks 5-7) performed in each set [Table 1].

Table 1: An overview of the seven-week training intervention showing number of sets, repetitions, rest time and intensity over the seven-week period. The same training was carried out for both the power clean and the loaded hex bar jump group.

Before each training session began, the athletes did a normal warm-up routine, consisting of running, dynamic stretching, and injury prevention exercises before starting with either the power clean or the loaded hex bar jump. Three warm-up sets were performed at each session with increasing load until the target load was reached with one minute rest period between sets. The target load for the power clean exercise was found based on their 1RM at their pretest. The target load for the loaded hex bar jump was found based on the Epley equation where a 3RM test was performed at the beginning of the first training session to estimate the 1RM (DiStasio 2014). Hereafter the training session started after a rest period of three minutes [Table 1].

Data processing

The CMJ height was calculated using flight time of the highest jump recorded with the contact mat using the following equation:

Jumpheight = Flight time2 * g / 8

g is defined as the gravitational acceleration, with the eight representing a constant factor.

A linear encoder was used in the present study to assess power output in loaded hex bar jumps. The linear encoder was attached to the hex bar and measured position as a function of time with a sampling rate of 1000 Hz. To compute power output, the distance from the lowest position before starting the concentric phase of the jump to the highest to the position just before take-off was calculated. Then, the force was calculated by multiplying the external mass of the loaded hex bar with g ( 9.82m / s2 ). Force and distance were then used to compute the performed work using the following equation:

Work = Force * distance

The work was then divided by the time elapsed in order to compute the power output using the following equation:

Power = Work/Time

This was done for the repetition at 61 kg and 81 kg in the loaded hex bar jump.

Statistical analysis

Normal distribution of all the data was confirmed using the Shapiro wilks test and homogeneity of the data was confirmed through Levene’s test of variance where no outliers were found based on excluding any data point above or below an upper (3rd quartile+(interquartile range times by 1.5)) or lower threshold (1st quartile-(interquartile range times 1.5)). An unpaired samples t-test was then conducted to investigate if a significant difference was found between groups at pretest and posttest, respectively. Furthermore, a paired samples t-test was conducted to investigate if a significant difference was found for each group from pre- to post-test in the performance tests (CMJ, 5-, 10-, 25- and 30-meter sprint time, COD, power clean 1RM and power output in the 61 kg and 81 kg loaded hex bar jump). Cohen’s d was then calculated to find the effect size (ES) of the difference in each condition. For interpretation of the effect sizes the following intervals were used in accordance with Cohen 2013: small (d = 0.2), medium (d = 0.5), and large (d = 0.8) [23]. Data are presented as mean ± standard deviation. Statistical significance was accepted at p≤0.05. All calculations were performed in SPSS version 28.0 (IBM Corp: Armonk, NY, YSA).

All data was normally distributed and not all players participated in each test.

The athletes included in the HX group (N = 10) completed the training intervention with a mean compliance of 83.9±7.1% while the PC group (N = 10) completed the training intervention with a mean compliance of 83.5 ±6.2%. The average training session volume for the HX group was 894.4±111.8 kg and the average training session volume for the PC group is 610.1±90.7 kg, resulting in a significantly higher training session volume being performed in the HX group (p<0.001) (ES=1.841) compared to PC group.

Loaded hex bar jump

No significant differences were found between pre- and posttest power output at 61 kg loaded hex bar jump for either of the PC (N=8) or HX group (N = 9) (Table 2). However, a significantly higher mean power output was observed in the posttest compared to the pretest for the 81 kg loaded hex bar jump in both the HX (N=9) and PC group (N=8) [Table 2].

Table 2: Average power output for 61 and 81 kg loaded hex bar jump in the pre- and posttest for the loaded hex bar jump group (HX) and the power clean group (PC). * Indicates a significant difference between pre- and posttest power output.

An unpaired t-test revealed no significant differences between HX and PC group at any of the loaded hex bar jump tests (p > 0.05).

Power clean

A significantly higher 1RM   in   power   clean   was   found in the posttest compared to the pretest for both HX (N = 9) (pre=53.9±8.6 kg, post=58.9±8.9 kg) (p<0.001) (ES=2.0) and PC (N = 8) (pre=51.9±6.5 kg, post=60.6±7.3 kg) (p=0.006) (ES=1.4) [Figure 4].

Figure 4: (A) Power clean one repetition maximum (1RM) for the loaded hex bar jump group (HX) (N=9). (B) Power clean 1RM for the power clean group (PC) (N=8). Gray lines indicate individual differences from pre- to post test. Black dots indicate individual athletes. Dark grey bar plot indicates group average. * Indicates a significant difference between pre- and post-test p ≤ 0.05.

An unpaired t-test revealed no significant difference in power clean 1RM between HX and PC at the pre- (HX=53.9±8.6 kg, PC=51.9±6.5 kg) (p=0.60) or post-test (HX=58.9±8.9 kg, PC=60.6±7.3kg) (p=0.67).

Countermovement jump

A significantly higher CMJ height was observed in the post- test (41.4±4.8 cm) compared to the pre-test (34.3±3.7 cm) for HX (N = 9) (p<0.001) (ES=2.0). Similarly, a significantly higher post-test CMJ (38.4±3.9 cm) compared to pre-test (33.9±3.7 cm) (p<0.001) (ES=2.0) was observed for PC (N = 7) [Figure 5].

Figure 5: A) Counter movement jump (CMJ) height for the loaded hex bar jump group (HX) (N=10). (B) CMJ height for the power clean group (PC (N=9). Grey lines indicate individual differences from pre- to post test. Black dots indicate individual athletes. Dark grey bar plot indicates group average. * Indicates a significant difference between pre- and post-test p ≤ 0.05.

An unpaired t-test revealed no significant difference in CMJ height between HX and PC in pre- (HX=34±3.7 cm, PC=33.9±3.7 cm) (p=0.68) or post-test (HX=41.4±4.8 cm, PC=38.4±3.9 cm) (p=0.69).

Change of Direction

A paired t-test revealed no significant difference from pre- (2.38±0.04 s) to post-test (2.33±0.12 s) for HX (N = 8)(p=0.34) (ES=0.13) and pre- (2.42±0.12 s) to post-test (2.37±0.12 s) for the PC group (N = 8) (p=0.14) (ES=0.09) in the change of direction test [Figure 6].

Figure 6: (A) Change of direction (COD) time for the loaded hex bar jump group (HX). (B) COD for the power clean group (PC). Gray lines indicate individual differences from pre- to post test. Black dots indicate individual athletes. Dark grey bar plot indicates group average. * Indicates a significant difference between pre- and post-test p ≤ 0.05.

An unpaired t-test revealed no significant difference in COD for HX and PC in pre- (HX=2.38±0.04s, PC=2.42±0.12s) (p=0.38) or post-test (HX=2.33±0.12s, PC=2.37±0.12s) (p=0.57).

Five, 10, 25 and 30-meter sprint

A paired t-test revealed a significantly slower 10-meter sprint time for PC group (N = 8) at the post-test compared to the pre- test (p = 0.02). No significant difference was found between pre- and posttest for 5-, 25- and 30-meter sprints for PC group (N = 8) or for HX group (N = 7) (p > 0.05) [Table 3].

Table 3: Sprint time for five-, 10-, 25- and 30-meter sprint at pretest to posttest for loaded hex bar jump group (HX) and power clean (PC) with effect sizes (ES). * Indicates a significant difference between pre- and posttest sprint time

An unpaired t-test revealed no significant differences in sprint time at pre, or posttest between HX and PC group for either 5-, 10-, 25- or 30-meter sprints (p > 0.05).

The purpose of this study was to investigate the effect of a seven-week strength training intervention using either the power clean or loaded hex bar jump exercise in enhancing performance in CMJ height, 5-, 10-, 25- and 30-meter sprint time, 505 change of direction ability, power clean 1RM and power output in a loaded hex bar jump. The primary finding was that seven-weeks of power clean or loaded hex bar jump training in general were equally effective in enhancing physical performance. As such, both groups significantly increased performance in CMJ height, power clean 1RM, and power output in the 81 kg loaded hex bar jump from pre-test to post-test.

Previous studies found an increase in power output after a training intervention focusing the power clean exercise [24] and the loaded squat jump exercise using a loaded barbell of 80% of 1RM back squat [25,26].

This is similar to the findings of the present study which found the loaded hex bar jump training and the power clean training to induce significant improvements in lower body power output as measured with the 81 kg load in the loaded hex bar jump test. However, no increase in power output was revealed for either the HX or PC group when performing the loaded hex bar power test with 61 kg. For the HX group, this may be explained by the fact that the majority of the athletes in this group performed the training intervention with a load of 80-95 kg in the hex bar jump exercise which is a higher load compared to the 61 kg loaded hex bar jump test. This might suggest that training adaptations only occurred specifically in the higher force portion of the force velocity curve, which have previously been shown to have a low transfer to the lower-force portion of the curve [27]. It is currently unclear why the PC group only showed significant improvements in the 81 kg loaded hex bar jump test as well, and not in the 61 kg test. Especially, considering that the athletes in this group trained with a lighter load than the HX group with a load between 40 and 60 kg, due to the technical constraints of the power clean exercise, which should be more specific to the 61 kg load tested. The results do indicate, though, a tendency for the PC group to improve in the 61 kg hex bar jump test, with a p-value of 0.16 and an effect size of 0.55.

Previous studies found an increase in power clean 1RM following a loaded squat jump focused training intervention [20] and a power clean focused training intervention [28]. These findings were similar to the present study`s result as an increase from pretest to posttest in power clean 1RM were found for both HX and PC group. No difference between groups was seen at the pretest or the posttest. As the PC group focused on the power clean exercise in the seven-week training period, it seems plausible that an increase in technical skill level and lower body power, as evidenced by the increase in CMJ and 81 kg loaded hex bar jump, can explain this progress. The HX group, however, only increased their lower body power as evidenced by the increase in CMJ and 81 kg loaded hex bar jump, but not likely their technical skill in power clean as they did not train this exercise. It therefore seems likely, that in the present sample of youth elite soccer athletes, with limited technical proficiency in the power clean exercise, that simply increasing the lower body power output of the triple extensor musculature can induce positive changes in power clean performance.

The present study hypothesized that a seven-week strength training intervention using the loaded hex bar jump exercise will result in a similar increase in countermovement jump (CMJ) height compared to the power clean intervention group. As expected, this hypothesis was supported by the present study`s result that showed a significant increase in CMJ height for HX and PC group from pre- to post-test. The increase in CMJ height is supported by recent literature which revealed that loaded jump training and power cleans are equally effective in this regard [11,29]. One study, however, suggests that the technical component of the power clean may inhibit the chance to overload the triple extension of the ankle, knee and hip and therefore result in a lower or no increase in CMJ following a power clean training protocol [30]. While another study has dismissed this claim and proposed that both the loaded squat jump and power clean can easily overload the triple extension musculature and increase CMJ height [21]. The latter study is supported by the results of the present study.

In the present study we also found no significant increase in sprinting performance which contradicts multiple other studies [6,8,17,25,31,32], while some studies are consistent with our findings [20,33,34]. The fact that a decrease in linear sprint speed was found in the 10-meter sprint for PC group in the present study might be due to the increasing fatigue generated over a soccer season as documented elsewhere [24]. As such, the pretests in the present study were performed after a recovery winter break, while the posttests were performed close to season end when the athletes had accumulated more fatigue. Furthermore, the decrease in linear sprint speed could be due to a shorter recovery period before the posttest, meaning that this test was carried out 40 hours after the last soccer match compared to the pre- test, which was carried out more than 72 hours after a soccer match. The negative impact of a lack of recovery is supported by the study by Nédélecal et al. [24], that reveals a recovery period below 72 hours may diminish the performance due to fatigue (28). It should be mentioned that a similar tendency was seen for the 25 m sprint test of the HX group, which tended to be slower at the post-test compared to the pre-test as well (p = 0.08). This was supported by recent findings from Mcbride et al. [26], who found a decrease in 20-meter sprint time after a heavy loaded squat jump training intervention [26]. However, as there does not seem to be any differences between HX and PC groups in any of the other linear sprint measures, it is also possible that the result is a simple case of a false-positive find. Based on the majority of the results it is not possible to falsify the hypothesis of the present study.

Lastly, the present study`s findings showed no effect of power clean training on COD performance which is contradicted by previous research [6,35], but supported by Morris et al. [30], However, both groups showed a tendency towards an increase with a 1.93% faster time for HX and a 2.26% faster time for PC in the COD test. However, this was not enough to surpass the significance level. As the COD and sprint measures were tested the same day, the same lack of recovery might be present at the post COD tests compared to the pre COD tests [24]. Again, it should be noted, that no significant changes were observed between groups, further indicating that the training interventions in the PC and HX groups induced similar results.

Due to time restrictions for the testing procedure, we were unable to incorporate extra repetitions in the loaded hex bar jump test using loads higher than 81 kg. This limitation restricted our ability to fully assess the athletes’ strength and power capabilities in the loaded hex bar jump exercise. Secondly, there were instances where the athletes did not have sufficient recovery time before certain testing sessions. This lack of adequate rest may have compromised the reliability of the test results. It should be noted that all athletes were equally affected by this limitation.

In conclusion, a training intervention including the loaded hex bar jump exercise induce similar improvement in CMJ height, 81 kg loaded hex bar power output and power clean 1RM as the power clean exercise. No differences were found between groups in any of the physical performance measures. None of these training interventions increased performance measures from pre to post test in any of the sprint measures or the COD test.

Practical Applications

The present study showed that loaded hex bar jump is equally effective as the power clean exercise for improving CMJ height, power output of a loaded hex bar and power clean 1RM. The loaded hex bar only requires a few familiarization sessions before effective training can be performed, whereas the power clean is more difficult to perform correctly and therefore is a more time-consuming exercise. As strength and conditioning coaches for large teams with many players have limited time with each athlete incorporating loaded hex bar jumps in their resistance training program could be an efficient variation to the power clean exercise. Furthermore, as all coaches do not necessarily have the technical knowledge to teach their athletes the proper technique used in power clean exercise the loaded hex bar jumps may prove easier to implement in the daily training due to the lower technical demands of this exercise, while still producing significant improvements in lower body power output.

The authors would like to thank all of the participants involved in the experiment. Further the authors report no conflict of interest, and no funding was received. The findings of the present study do not endorse any of the equipment mentioned in the paper, by the authors.

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