*authors note: this article was originally written to assist a colleague who works in a sport environment and was facing resistance from a management group that did not want to permit Olympic weightlifting or plyometric training due to concerns over injury risk

Introduction

A major concern of implementing the Olympic weightlifting (OL) exercises and plyometrics (plyo) into a sport performance program is the perceived risk of injury erroneously associated with these exercises.  This concern is largely the result of assumptions made by coaches, parents, and program managers regarding the risks associated with moving loads at high rates of speed.  As a result, some are hesitant to program OL and plyos into a performance program. 

Not every program requires OL and plyo prescriptions, and not every coach is capable of implementing these types of activities.  In order to determine whether to implement the OLs or plyos into your training program you must perform a needs analysis.  A needs analysis should consider all of the requirements of your athletic population and how to best meet these needs through strength and conditioning principles.  Part of this needs analysis will include decisions regarding, but not limited to, the following:

1. Which exercises will be superior for meeting the training goals?
2. Which programs are most efficient in reaching athlete goals the fastest and safely?
3. What are the risks associated with the training program?
4. Am I able to effectively implement the program?
5. Is the athlete physically and mentally capable to progress in these lifts?

In this brief review, evidence will be provided that will help in determining whether OLs and plyos will meet your athlete’s needs along with some guidance for understanding the injury risk associated with both activities. 

Trends in the Industry

Evidence-based practice is the cornerstone of rehabilitation and performance training, however, those who work in the industry realize that sometimes there are limitations to relying on research in making treatment and training decisions.  Individual differences, outliers, external validity, and choice of independent variables will frequently limit the availability of quality research that is applicable to many performance training settings.  In short, given there are so many variables at play, and many individual differences, making blanket statements regarding the superiority of one type of training compared to another is not prudent.   As a result, perhaps it is best to weigh experience equally with research as part of the decision making process. 

Thirty years ago in the United States, OL and plyo training was in its infancy.  Very little research existed and few were applying these modalities to athletic conditioning.  In general, the concept of performance training for sport was also in its infancy.  The strength and conditioning industry has since grown with top-ranked university strength and conditioning programs being supported by multi-million dollar budgets and extensive facilities.  The vast majority of these facilities have OL areas and plyo equipment, and implement these techniques as part of their performance training.  Strength training machines have virtually disappeared.  The all-machine, one set to failure HIT programs (not to be confused with HIIT), are in the past and no longer pervade top university and pro sport programs. 

The strength and conditioning industry is largely driven by performance-based outcomes, therefore it can be assumed that this evolution of the past three decades is the result of overall positive training outcomes.  If there were risks that outweighed benefits, surely this would have become apparent, and programs using OL and plyos would have been eliminated by now. 

In Canada, in the past ten years, there has been a transition from the OLs being feared to now being widely accepted as more individuals learn about the lifts and their applications.  Universities in Canada are now employing full-time strength coaches and equipping new training facilities with OL and plyo training areas.   Again, this investment cannot be purely associated with a passing trend and implies that the impetus is moving towards the integration of these movements within athlete development programs.

OL Injury Rates

The research studying injury rates in OL is limited.  One major study by Calhoon and Fry (2) examined elite competitive American OL athletes and determined that the majority of injuries experienced were related to overuse.  Tendonitis and tendinopathies were fairly common (mostly knees), as well as muscle strains (mostly back and shoulders).  It was very rare that any athlete experienced traumatic joint damage and the average time lost for a reported injury was one practice day.

In a study by Junge (12) the injury rates of Olympians at the 2008 Beijing games were compared to other sports and it was found that OL athletes experienced injuries in the higher quartile of injury rates, and again they were related to overuse and were usually muscle strains. 

Judging by this information alone you may conclude that OLs are of high injury risk, despite the injuries being minor in nature, however, you must consider the nature of training for this sport.  An elite level lifter will train 3-6 hours per day, 6-7 days per week.  In a given week they will squat 11-23 times (for multiple sets) with loads generally in excess of 80% of 1RM.  Similar to that experienced in marathon runners, the potential for overuse injuries is tremendous.  In general, training at the elite level of sport is not healthy from a muscuoloskeletal injury standpoint.  Athletes at a top-level often walk a fine line between performance gain and injury risk.  It is therefore not valid to compare elite level injury data to a population that would be applying these lifts at a much smaller volume.

Perhaps a better comparison of OL injuries to be made would be between those who use them more recreationally.  A study by Hamill (9) comparing injury rates among OL, powerlifting and weight training found that the injury rates were similar amongst all of them, and that overall rates of injury were quite low when compared to other sports, including running.  They also concluded that injury rates were lowest when competent coaching was provided.  As a result, to eliminate OL purely on the basis of injury risk seems unwarranted, specifically when you consider the general rates of injuries in other recreational activities.  

Anecdotally, if implementing OL in a performance training environment, the major concern is with inducing Jumper’s Knee, a condition of tendinopathy of the common quadriceps or patellar tendon.  The repeated and forceful knee extension combined with high impact landing, when combined with squatting, sprinting and plyos will often exceed the tissue tolerance of the athlete.  Load and volume should be gradually introduced to avoid this, and alternative training plans created as soon as symptoms are noticed.  In youth under the age of 16, a similar etiology will result in Osgood Schlatter’s disease, a condition of growth plate irritation at the tibial tuberosity that is exacerbated by rapid skeletal growth.

The next most common issue that will be experienced with the introduction of OL will be irritation at the wrist from holding the bar in a shoulder rack position in a clean or front squat.  In extreme cases, this can result in osteochondral lesions (bone bruise).  Generally, this discomfort can be relieved with wrist taping or wrist wraps, combined with aggressive daily stretching of the wrist joint.  Athletes with wrist pathology that restrict range of motion should avoid the front rack position and perform snatches instead.

When snatching or jerking, an unstable overhead position could result in the irritation of the muscle-tendon complex of the rotator cuff, specifically the supraspinatus tendon.  This can be avoided by teaching activation of the trapezius and back musculature to avoid excessive scapular movement with load overhead.  Beyond these injuries, there will be some risk of muscle strains, most commonly in the lower and upper back, and less commonly in the legs. All injuries are greatly reduced through the use of proper technique and gradual load progression. 

Plyo Injury Rates

As plyos are not a sport, it is more difficult to track injury rates, although inferences could be made from any sport that involves high intensity running or jumping movements.  Literature searches including “plyometrics” and “injury” result in some interesting hits.  The majority of these hits examine the role of plyo training in preventing injury in athletic populations.

Several studies have examined how training can influence injury risk through education of complex motor skill.  Myer et al. (16) used a group of female athletes to assess changes in performance and movement mechanics that occur with a multi-dimensional training program that included plyometrics.  They determined that not only did performance measures improve, but movement mechanics also improved.  Measures of knee valgus and varus torques decreased during the landing phase of a vertical jump and they concluded that this change would decrease the risk of ACL rupture in this population.  The same research group then followed up with a second study comparing plyo training alone to dynamic balance training and their effects on the mechanics of landing (15).  They found that plyo training affects sagittal plane kinematics primarily during a drop vertical jump, whereas balance training affects sagittal plane kinematics during single-legged drop landing, and therefore concluded that both types of training would be necessary to best protect the knee joint during landing. 

Similar conclusions were also made by Chappell and Limpisvasti (4), and in a review of best practices for preventing non-contact ACL injuries in female athletes it was concluded that “The successful programs teach athletes to control the upper body, trunk, and lower body position; lower the center of gravity by increasing hip and knee flexion during activities; and develop muscular strength and techniques to land with decreased ground reaction forces. In addition, athletes are taught to preposition the body and lower extremity prior to initial ground contact to obtain the position of greatest knee joint stability and stiffness.” (1, p.49).  The best way by which to teach an athlete how to control their body during dynamic explosive motions appears to be by completing these tasks under controlled conditions.

Anecdotally, injuries in plyos are the result of overuse and poor control of impact surfaces.  Plantar fasciitis and lower leg compartment syndromes (shin splints) will be induced if jumping on a hard surface (ie. concrete) with poor footwear.  This outcome will have a dose-response relationship.  Select surfaces with some impact absorption such as grass, turf, suspended hardwood, or >1/2 inch rubber to avoid these impact injuries. 

Poor jump box design frequently results in shin contusions and abrasions, and there are also risks of falls that can be mitigated by using open jumping areas and implementing spotting protocols.  Similar to OL, introducing plyo at high volume and/or load too quickly will result in Jumper’s Knee, which should be dealt with aggressively by reducing training load or implementing an alternative training plan.

Specificity of Adaptation

Before exploring the specific benefits of OL and plyos in a training program, it is worthwhile to examine principles of training adaptation.  The SAID (Specific Adaptation to Imposed Demands) principle states that the body responds to a stressor by building resistance to the stressor.  Wolff’s Law states that a bone under load will respond by growing thicker and stronger.  This Law apparently applies to many of the structures of a mesodermic origin, including connective tissue and muscle. 

A classic example of Wolff’s law at work is demonstrated by Conroy et al. (6) who assessed bone mineral density in elite junior Olympic weightlifters and compared it to age-matched controls.  They determined that the bone mineral density of the Olympic weightlifters far exceeded that of the control group.  As bone and connective tissue respond most favorably to high rates of strain, as opposed to high magnitudes of strain, movements such as the OLs and plyos would promote the greatest benefit in these areas.  Few would argue against the protective effect that this could have for an athlete participating in high impact sports.

The SAID principle at work was also applied to the discussion of injury above, whereby through training, more efficient and safe techniques were learned for jumping technique.  To demonstrate this you could compare the mechanics of jumping of a five-year-old to a well-trained basketball player.  The child will likely have a choppy, poorly timed movement and a hard, stomping landing while the athlete will be smooth and fluid with a soft landing.  This movement is a well-learned task, and the way it is best learned is by doing it repeatedly with good coaching of mechanics, and progressive overload.  It will not occur spontaneously.

In the weight room you are attempting to transfer specificity of overload to a field setting to enhance the following:

• Speed
• Agility
• Quickness
• Power
• Strength
• Endurance capacity

The two weightroom activities that can meet all of these needs are the OLs and plyos.   General strength training will not optimize these skills.

Performance Improvements with OL

Loren Chiu (5) provides a summary of the physiological changes that occur with OL.  Briefly, the OLs, which include the snatch, clean and jerk, and related exercises, are full-body resistance training exercises that utilize forceful muscle contractions applied at high rates of speed to move a weight rapidly over a vertical distance.  In essence, they are vertical jump exercises with load. 

By all definitions, the OLs are extremely high power output movements.   Garhammer (7) performed measures of power output for the OLs and measured jerk movements that exceeded 4700 watts.  As a comparison, elite Olympic rowers are producing around 1000 watts and sprint cyclists may break 2000 watts.  The power output of the OLs far surpasses all other sporting movements due to the explosive movement performed under load.

Research comparing OL to other forms of training are limited as the studies are hard to do with untrained populations due to the high skill demand.  There are some studies that compare OL to plyo and/or general strength training.  Tricoli et al. (20) compared the OLs to plyo training and concluded that the OLs tended to permit broader improvements in performance as measured using a battery of sprint, jump and power tests.  Hoffman et al. (11)  compared OL and powerlifting training and found that OL significantly improved vertical jump performance when compared to powerlifting, and improvements in sprint speed were twofold greater with OL than powerlifting.  Channell (3) also concluded that OL, as well as powerlifts, provide improvement in vertical jump performance and that OL may provide a modest advantage over powerlifts for vertical jump improvement in high school athletes. Similarly, Hawkins et al. (10) compared OL, plyo and weight trained groups on measures of jumping and lower body power and found OL superior to plyo and weight training.  Much of this data was later summarized in a meta-analysis by Hackett et al. (8) who determined a significant effect of OLs on vertical jump that is not matched by traditional resistance training. 

Performance Improvements with Plyo

Plyometric training is hard to define and therefore it is sometimes difficult to identify when an exercise is a true plyometric or a basic jump activity.  Plyometrics involve a movement with a rapid, high load eccentric component, followed by a maximal explosive concentric movement. The eccentric and concentric movements are separated by a brief amortization period.  The amortization period is the time it takes to transition from eccentric to concentric movement and needs to be minimized for an activity to be defined as a plyometric.  When loosely applied, any sprinting motion could be considered a lower-body plyometric, however, traditionally, a plyometric would include a preload such as is performed during depth jumps.  There are therefore many types of plyometric activities for the upper and lower body, some of which could include load, while others being performed with bodyweight only.

There are several reviews and meta-analyses that examine the use of plyos in improving measures of athletic performance.  Overall the consensus is that plyos are effective for increasing vertical jump performance (lower body power)  and to optimize performance, a combination of jumping should be applied using bodyweight and external loading (14,18). 

Studies examining the role of plyos in developing lower body power are favorable.  Hawkins et al. (10) concluded that high-velocity and high-force training programs, consisting of weightlifting and plyometrics, were superior to weight training for improving lower-body performance, especially in the areas of jump height and power.  Meylan et al. (15) found that plyo training enhanced sprinting performance, change of direction, and vertical jump in soccer players.  Thomas et al. (19) also concluded that depth jumps and plyos are effective for enhancing power and agility in youth soccer players.  Most evidence seems to be in favor of plyos improving athletic performance, however many studies are simplistic in their comparisons of treatment interventions, and broad in their choice of measurement outcomes. 

Studies that used plyos in combination with other training techniques have also demonstrated their effectiveness.  Perez-Gomez et al. (7) concluded that 6 weeks of combined OL and plyo exercises results in significant improvement of kicking performance, as well as other physical capacities related to success in football (ie. soccer).  Kotzmanidis et al. (13) showed that by combining strength training and plyos (sprinting) there were improvements in 30-m sprint, squat jump, and countermovement jump when compared to strength training only and the control group.  Overall, the studies supporting plyos for improving lower body power, are numerous, and demonstrate their superiority to more traditional resistance training.

Conclusions

When determining the appropriate approach to a human performance program, it is necessary to find the most efficient and effective path for enhancing performance without placing the athlete at undue risk.  This requires applying effective coaching to controlled movements that will allow for transfer into the sporting arena.  The OLs and plyos are two approaches to training that have been demonstrated to result in superior performance gains in measures related to sporting performance, with minimal risk.  In fact, performing these activities under proper supervision may actually prevent significant injury on the field. 

It is the responsibility of professionals working with athletes to recognize if appropriate applications of OL and plyo training meet the athlete’s abilities and needs.  Additionally, it is also the responsibility of professionals to be well educated in coaching appropriate technique when required.  If either of these expectations are not being met, then it is possible that OL and plyos will have limited performance outcomes and may actually result in injury.  It is therefore up to the professional to make the determination as to whether they can effectively implement the program or seek out educational programs to provide the skills necessary for their implementation.

References

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5.            Chiu, L and Schilling, B. A primer on weightlifting: From sports to sports training. Strength and Conditioning Journal 27: 42–48, 2005.

6.            Conroy, B, Kraemer, W, and Maresh, C. Bone mineral density in elite junior Olympic weightlifters. Medicine and Science in Sports and Exercise 25: 1103–1109, 1993.

7.            Garhammer, J. Power production by Olympic weightlifters. Medicine and Science in Sports and Exercise 12: 54–60, 1980.

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9.            Hammill, B. Relative safety of weightlifting and weight training. Journal of Strength & Conditioning Research 8: 53–57, 1994.

10.         Hawkins, SB, Doyle, TLA, and McGuigan, MR. The effect of different training programs on eccentric energy utilization in college-aged males. Journal of Strength & Conditioning Research 23: 1996–2002, 2009.

11.         Hoffman, JR, Cooper, J, Wendell, M, and Kang, J. Comparison of Olympic vs traditional power lifting training programs in football players.  Journal of Strength & Conditioning Research 18: 129–135, 2004.

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20.         Tricoli, V, Lamas, L, Carnevale, R, and Ugrinowitsch, C. Short-term effects on lower-body functional power development: Weightlifting vs. vertical jump training programs. Journal of Strength & Conditioning Research. 19(2): 433-437, 2005.

Author:

Trevor Cottrell, PhD

Dr. Cottrell is a professor of Kinesiology and Health Promotion at Sheridan College.  His education includes an undergraduate degree in Kinesiology from the University of Waterloo, a Masters degree in Exercise Science from Northern Arizona University, a doctoral degree in Physiology from the University of Arizona, and postdoctoral work at Queen’s University. He has been a practicing strength and conditioning coach for 28 years and currently coaches an Olympic weightlifting program in Guelph, Ontario.