In each debrief, we break down articles related to performance development, sport science, and training theory. Our goal is to bridge the gap between science and practice, empowering coaches to become practitioners who move the profession forward.

By Christopher Taber, PhD, CSCSD, CPSSD, USAW3, EP-C

Inside This Issue

1. Effects of Expertise on Muscle Activity during the Hang Power Clean and Hang Power Snatch Compared to Snatch and Clean Pulls – An Explorative Analysis
2. Dynamics of the Snatch Technique Cinematic Parameters in Qualified Female Weightlifters during Different Periods of Training Macrocycle

Muscle Activation During Clean and Snatch

Study: Effects of Expertise on Muscle Activity during the Hang Power Clean and Hang Power Snatch Compared to Snatch and Clean Pulls -- An Explorative Analysis

Do alterations in muscle activity occur as athletes develop? What if any changes in muscle activity are present during different variations of the lifts? 

Introduction 

Researchers use electromyography (EMG) to examine the activation of various muscles during human movement. In order to examine muscle activation patterns, researchers place surface electrodes on top of key muscles of interest to measure the electrical activity and activation patterns during movement. Analysis of muscle activation patterns in the snatch and clean and jerk have been conducted early in the biathlon era by researchers in the Soviet Union (1). During these studies they examined the time and muscle activation patterns during each phase of the lift to determine which muscles were most active at key moments in order to develop them for competition. In addition, a technical analysis could be determined to help explain what changes in technique may be needed as the athlete develops.

Early studies examined the effect of loading on the muscle activation when intermediate and advanced lifters went from submaximal to maximal loading (2). No differences were observed between groups in either the classic snatch or clean and jerk in all loads examined. This indicates similar muscle activation patterns across the lifts and all loads encountered. Other studies have examined different lift variations and how they change with increasing load. These studies tend to show increases in muscle activity as the load increases with a plateauing effect as loads increase beyond 80% of the athlete’s maximum (3, 4, 5). Therefore, the present study fills a gap in the literature where the authors compare pulling exercises versus power variations and examined muscle activation. The authors highlight the lack of research in this type of analysis. 

Purpose

The primary purpose of this study was to examine muscle activation via EMG during the hang power clean (HPC), hang power snatch (HPS), hang clean pull (HCP), and hang snatch pull (HSP). The secondary purpose was to examine the effects of expertise on the activations patterns by comparing beginners, intermediate, and advanced weightlifters. In this study, the authors posited two hypotheses based on previous research. The first was that muscle activation would be different between the hang lifts with a catch versus the lifting derivatives. Second, that activation patterns would be different with changes in lifting expertise. 

Methods

Subjects

27 weightlifters (15 men and 12 women) participated in this study. Beginners had 0-2 years of training, advanced 2-5 years, and elite >5 years. See table 1 for a breakdown of the categories. All subjects need to have trained consistently for six months and be free of injuries. 

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Table 1. Subject Characteristics. 

Methods

Subjects completed two sessions. The first was a one repetition maximum of the HPS or HPC exercises. They were randomly assigned to max either exercise first then the other exercise test occurred after a brief rest period. The next session was the experimental session where researchers affixed EMG electrodes to the vastus lateralis (VL), gluteus maximus (GM), rectus abdominis (RA), erector spinae (ES), and the trapezius (TZ). Following this, subjects performed a maximal voluntary isometric contraction of each muscle group. By doing this, the muscle activation of each exercise can be compared against a known contraction stimulus for comparison. Following the isometric baselines testing began. Subjects were randomly assigned to either the HCP or HSP group to start testing. The subjects would complete the pulling test followed by the exercise matched power version of the pull. After this, the other exercise was completed in the same order for all subjects. See figure 1 for a breakdown of study methods. 

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Figure 1. Schematic of methods used in study. 

Results

Power clean and derivatives outcomes

No difference in primary movers (VL and GM). Stabilizers (RA and ES) responded differently for beginners with greater activation during the power clean. The traps responded to a greater extent to the power variations at lower loads with the elite and advanced group. 

Snatch Outcomes

No difference in the primary movers (VL and GM) alongside the abdominals. However, the erector spinae was activated to a greater extent during pulling movements in the advanced and elite groups. The beginners showed different responses that favored the pulling variations. The traps had little difference in both versions with only a small difference in beginners. 

Effect of training level

No differences were observed between beginners, intermediates, and advanced lifters. 

Discussion

The main outcome of this study was that the large primary muscles of the lower body are trained in a similar manner across loading in the snatch and clean alongside their derivatives. Differences are found in the stabilizing muscle and potentially the trapezius. Interestingly, no effect was found for expertise on muscle activation.

It is unsurprising that muscle activation of the primary movers did not differ between variations. First, the load encountered was the same between full lifts and the derivatives. This likely drives similar amounts of muscle activation unless you radically alter your technique. Additionally, these variations were all done from the hang position which is going to challenge similar muscles in the execution. 

While not statistically different, you can see the elite group produces more activation of the primary movers (% of MVIC) compared to advanced and beginners.  This likely results in their greater strength levels that were measured before the study. As you look at the stabilizers, you can see differential activation between the levels where advanced but not elite athletes have more activation. There may be changes in technical adaptation over time where the better trained and stronger your muscle groups are you can use them more favorably across loads and allow you to express force more effectively. 

Finally, there are differences in muscle activation between the snatch and clean and jerk. You can see the %MVIC is different between both pulling and catch variations for each specific lift. Due to the principle of specificity it’s likely that if you are trying to improve a specific lift you should perform that lift under similar conditions. Finally, pulls are typically trained heavier than the main lifts so this may increase the muscle activation compared to the full lift but more research is needed to determine if this occurs. 

Practical Applications 

During power and pulling variations muscle activation of major muscle groups is similar across similar loads. However, unlike the primer movers in the lifts the trunk muscle activation was different across loads. Finally, there was no effect of expertise found. Similar muscle activation was found between beginners, advanced, and elite athletes. For these reasons, pulling exercises can be used alongside full lifts to develop key musculature in weightlifters to improve performance. Additional considerations should be given to developing the trunk musculature to help support the major developmental exercises. 

References

1. Vorobyev (1978) A Textbook on Weightlifting

2. Häkkinen, K., Kauhanen, H., & Komi, P. V. (1984). Biomechanical changes in the Olympic weightlifting technique of the snatch and clean & jerk from submaximal to maximal loads. Scand J Sports Sci, 6(2), 57-66.

3. Nagao, H., & Ishii, Y. (2021). Characteristics of the shrug motion and trapezius muscle activity during the power clean. The Journal of Strength & Conditioning Research, 35(12), 3288-3295.

4. Dryburgh, I., & Psycharakis, G. S. (2016). Muscle activation under different loading conditions during the power clean. International Journal of Performance Analysis in Sport, 16(2), 464-474.

5. Barnes, M. J., Petterson, A., & Cochrane, D. J. (2021). Peak power output and onset of muscle activation during high pull exercise. The Journal of Strength & Conditioning Research, 35(3), 675-679.

Changes in Snatch Technique

Study: Dynamics of the Snatch Technique Cinematic Parameters in Qualified Female Weightlifters during Different Periods of Training Macrocycle

How does the snatch develop across a macrocycle? What metrics can we track to understand these changes and evaluate technique? 

Introduction

Some of the earliest analysis of weightlifting performance was the examination of barbell trajectory (1). Researchers were able to quantify the phases of the lifts and how the barbell moved in space by tracking the movement during the snatch, clean and jerk, and clean and press. Since this early study, a multitude of researchers have conducted barbell trajectories over time and across varying levels of athlete performance (2,3). Coaches can use the analysis of barbell trajectories to examine technique during a session, track changes over time, and provide proscriptive exercises to improve technical execution. 

By using video analysis coaches can calculate various aspects of barbell trajectory. Of importance to coaches are the variables of barbell height (Ymax below), horizontal movement (xloop below), and barbell drop (y drop below). Of critical importance is the barbell height because the bar must be pulled high enough for athletes to get underneath and fixate the bar overhead. Indeed, early research determined that in the snatch the bar must be pulled between 62-78% of the athlete’s height and in the clean it must be between 55-65% (4,5). By understanding the trajectory and bar height, coaches can help to determine what exercises may be necessary to help improve this metric over time. 

Figure 1. From Cunanan 2020 (2)

Purpose

To examine the changes in technique over time by measuring barbell trajectory parameters 

Methods

During three phases of training, 21 Ukrainian female weightlifters had their technique of the snatch exercise analyzed during attempts at 90% of one repetition maximum or greater. The researchers grouped the athletes into light weight, middleweight, and heavy weight groups.  In total 189 successful lifts were analyzed by video analysis and customized software that determined trajectory and various other biomechanical metrics. While not well described, it appears they took measurements in the general preparatory phase, specific preparatory phase, and competition phases for these athletes. From the analysis, the metrics calculated were: maximum lift height, lift height at maximum speed, and clean height in squat (in this case means height at time of fixation or y catch above). 

Results

Light weight class (48, 53, 58)

Differences in bar height were observed between preparatory and intermediate phases. Greater bar height was obtained in the competitive phase compared to the preparatory phase. Height at vmax followed a similar trend where height was depressed during the preparatory phase and was higher in the intermediate and competitive phases. Finally, the height of the barbell at fixation was lower during the preparatory phase. 

Middle weight class (63, 69, 75)

Decreases in catch height were observed but only different between intermediate and competitive phases. Bar height at max velocity and fixation was lower in the competitive phase compared to preparatory and intermediate phases. 

Heavy weight class (-90, 90+)

No statistically significant differences between lift height in this group. Bar height at max velocity was different in the competitive phase compared to the intermediate and preparatory. Differences were observed across phases for fixation in this group with lower values being obtained in the competitive phase.  

Discussion

The primary outcomes from this study were that barbell trajectory changes across the training period (macrocycle level) and that different weight classes demonstrate diverging changes over time. Specifically, each athlete should be considered individually, and their weight class, and body proportions should be considered. Coaches should expect alterations during the phases of training and have quantifiable measurements to compare against over time. 

The first variable examined was maximum lift height. Unsurprisingly, bar height increased as the weight classes increased. In general, taller athletes are found in heavier weight classes and therefore the barbell must be pulled higher in order to be successful. This aligns with previous literature, however, the bar heights in this study are higher than previously reported early research but more in line with modern competition (2,4). This could be due to the fact that all earlier literature was conducted on males in one particular training system and later studies included women from various programs across the world. During the preparatory phase the lighter weight classes demonstrated greater decreases in bar height during successful lifts. interestingly in all classes this metric shows wide variability in the athletes which could be indicative of individual responses to the imposed training programs. 

Next, height at maximal bar speed was analyzed. It appears for lightweight lifters during the preparatory phase this variable decreases more than other weight classes. An explanation is not provided but this could be due to fatigue. In middle weights and heavy weights this parameter drops in the competitive phase. This also follows the bar height in the competitive phase so some speculation could be given that heavier weights are being attempted during this time which may reduce the speed and bar height during these successful attempts. Just like the max bar height metric, substantial variation (standard deviation) of max velocity bar height is observed during the preparatory phase. This is likely due to the inter-athlete variability in fatigue. Interestingly both these parameters show little variation during the competitive phase which may be due to the stabilization of technique. 

The final aspect analyzed in this study is the height of fixation of the barbell. This determines how far the barbell drops from max height to stabilization. Small changes are observed in these weight categories with less of a clear trend across phases. Ideally, the bar max height and bar drop is minimized so that the bar does not crash down on the athlete resulting in press outs or missed attempts. Because the catch height is relatively similar but the max bar height changes quite frequently, this indicates that athletes are meeting the bar in a similar catch position each time and may be due to flexibility and anthropometrics. This was a well trained to elite group of lifters so we can assume they likely have optimal mobility. Therefore, focus should be on the timing of the turnover and maximal bar height not attempting to catch lower. 

There are some limitations with this study. First, we do not know the volumes lifted by each athlete in each category which could reflect the amount of fatigue present. Next, the authors grouped athletes together into broad categories. This may help with analysis, but heights will be different between even these classes. Finally, only successful lifts were used for analysis. It is unknown what occurred in the unsuccessful lift and how many attempts they took in training. Without this knowledge it’s unclear what exercises could have been used to improve the performance and technical execution in these athletes. 

Practical Applications 

Bar height is critical for successful attempts in the snatch lift. Training should be dedicated to displacing the barbell to the optimal height as absolute loading increases. Fixation height is less important from this analysis, so when athletes are mobile enough to meet the bar properly the focus should be on pulling the bar to an adequate level and meeting it in the same catch position each repetition. Each athlete should be considered separately from a technical analysis standpoint. Significant variations occur during preparatory phases likely due to fatigue and technique tends to reverse course and stabilize during competitive phases. Finally, quantification of barbell trajectory provides coaches with measurable and actionable information to base decisions on in training. 

References

1. Ono, M., Kubota, M., & Kato, K. (1969). The analysis of weight-lifting movement at three kinds of events for weight-lifting participants of the Tokyo Olympic Games. The Journal of sports medicine and physical fitness, 9(4), 263-281.

2. Cunanan, A. J., Hornsby, W. G., South, M. A., Ushakova, K. P., Mizuguchi, S., Sato, K., ... & Stone, M. H. (2020). Survey of barbell trajectory and kinematics of the snatch lift from the 2015 world and 2017 Pan-American weightlifting championships. Sports, 8(9), 118.

3. Cunanan, A. J. (2019). Barbell Trajectory and Kinematics during Two International Weightlifting Championships (Doctoral dissertation, East Tennessee State University).

4. Roman RA. The Training of the Weightlifter. Moscow, ID: Sportivny Press, 1986. pp. 40–74.

5. Ai, K., Bi, Z., & Liu, G. (2018). Bar heights needed for successful lifts in men’s weightlifters. ISBS Proceedings Archive, 36(1), 899.