Plyometrics

Plyometrics Basics

     Plyometric training incorporates rapid, fast-twitch type exercises [14]. A plyometric exercise is an activity that enables a muscle to reach maximal force in the shortest amount of time [5]. Increasing muscles’ ability to accept, absorb, and return force efficiently is the primary goal of plyometric training [14]. Plyometrics are quick, powerful movements using pre-stretch or countermovements to activate the stretch-shortening cycle (SSC). These exercises encompass an athlete’s reactive strength and aim to increase subsequent movements’ power by using a combination of the natural elastic properties of muscles, tendons, and the stretch reflex [5]. Reactive strength refers to an athlete’s ability to engage the stretch-shortening cycle--if an athlete can engage the SSC in response to eccentric loading, higher forces can be generated during the concentric phase of a movement  [2]. When used correctly, plyometric training improves muscle force and power [5]. It is important to remember that if a concentric action doesn’t occur immediately after that eccentric action or the eccentric phase is too long (or requires too great a range of motion), the stored elastic energy is lost [5]. It is imperative to keep this in mind when selecting plyometric exercises for training. Much like strength training, the effects of plyometric training can be categorized as either neural or architectural. 

     Architectural effects of plyometric training include increased tendon elastic energy storage and increased tendon stiffness [14]. When plyometric training is adequately dosed, elastic tissues (like tendons) adapt to tolerate more force and increased efficiency in storing and releasing energy [14]. Optimal tendon stiffness combined with the ability to quickly couple forces may be the primary mechanism in increasing the energy storage of tendons working with muscles. It is important to note that some degree of tendon stiffness is essential for energy transfer and gymnastics skill power [14]. 

     Plyometric training’s neurological effects include increased neural firing rate, increased motor unit recruitment, increased stretch reflex excitability, increased intramuscular and kinetic chain coordination, and increased disinhibition leading to increased CNS contribution [14]. These effects are outlined in the table below. 

     Plyometrics, often referred to as plyos for short, can be categorized as low, medium, and high impact/intensity [14]. These categories are based on the speed of repetition and force produced or absorbed by the body [14]. During single-leg plyometric drills, ground reaction forces are higher than double-leg plyometric exercises and place more stress on muscles, connective tissues, and joints of the working leg [5]. The higher speed of movement increases the intensity of the plyometric drill [5]. The higher the body’s center of gravity (i.e., the box height, etc.), the higher the force upon landing [5]. Lastly, the greater an athlete’s body weight, the more stress is placed on the muscles, connective tissue, and joints. External load in the form of weight vests, ankle weights, and wrist weights can be added to advanced athlete’s bodies to increase intensity [5]. Please save these high-intensity drills for gymnasts who are physically mature and possess sufficient base strength. 

     Plyometric dosing is most often measured in ground contacts, loading per rep, and the intensity as mentioned above (prescribed based on training and developmental age) [14]. When used in the proper dosage and adequate understanding of the training effects, plyometric training serves an enormous benefit to gymnastics training [14]. This is especially true when built into the formal strength program structure with proper periodization [14]. Plyometrics are currently widely used in gymnastics; however, coaches generally lack an understanding of plyometric training at the physiological level. Often this results in overdosing the athletes or implementing sudden spikes of plyometric work, whether that is by suddenly increasing the intensity of the exercises, not considering the total volume. 

     The sport of gymnastics is almost entirely plyometric--meaning that regular practices involve high amounts of impacts to both the upper and lower body. It has been determined that gymnasts take impacts of up to 3-8x their bodyweight while landing skills, depending on the type of skill and landing (“stick” type landings versus reactive landings between the elements in a series of skills). Gymnastics is also a unique sport in that it requires the athletes to take a high number of hard impacts directly to the upper body. Unfortunately, in the gymnastics world, plyometrics are quite misunderstood. They are often implemented as warm-ups or conditioning strategies rather than strategically implemented as part of a balanced strength training program. This misuse, combined with the fact that this type of training rarely includes building a strength base (or using any kind of resistance training for that matter), or first focusing on proper landing mechanics, can lead to high rates of overuse injuries. Without landing mechanics training and building a base of strength, landings during conditioning and skills training are not dispersed throughout the involved musculature. Instead, they are absorbed repeatedly through the ankle, knee, and lower back, leading to problems down the line. 

     It is common for athletes to walk into the gym and perform a plyometric warmup beginning as young as 5 or 6 years of age. The warmup will often include hopping onto and off of low objects in quick succession and with the addition of various gymnastics specific actions in the air (tuck jumps, split jumps, etc.). There is very little rest, if any, between rounds, so by the end of the 5-10 minute warmup period, the gymnasts may have already racked up well over 100 foot contacts, and this is just the warm-up. Later, those same athletes will likely perform “leg conditioning,” which typically consists of a high number of jumping type exercises (alternating split squat jumps, tuck jumps, rolling candlestick jumps, squat jumps, etc.). Unfortunately, most of the gymnasts participating in those activities have never been taught the correct form for the base exercise (non-plyometric split squat, squat, etc.), much less trained these movements with any resistance. I have even seen the extreme at which a gymnast who cannot perform a bodyweight lunge correctly is asked to complete a high volume of alternating split squat jumps (often called jumping lunges or mountain climbers). Again, these exercises are typically performed in a circuit format with very little rest or none at all between exercises and sets of 10-15 repetitions. After this conditioning session, the gymnasts are expected to complete several more hours of skills practice, which by nature, includes many more plyometric actions. To top it off, when gymnasts are struggling to perform certain activities due to fatigue, most coaches take that as a sign that they need more conditioning and double down on increasing numbers. Coaches must remember that they are working with children and adolescents who are not fully developed. Plyometrics can be used to prepare gymnasts for the high levels of force and the immense volume of impacts that come with competing high-level gymnastics. However, coaches must implement proper progression, dosage, and gradual increases in intensity [6]. 

 

     Plyometrics are just like any other gymnastics skill: there are proper progressions and physical preparation guidelines to follow when teaching a skill, and the same concepts apply to plyometrics! 

Practical Application and Recommendations

 

     Contrary to the previous description, plyometrics used strategically are highly beneficial for training gymnasts. Plyometrics right out of the gate with no warm-up are never recommended, instead, try to schedule plyometric work close to the beginning of the day. Young gymnasts who are in the process of building up their strength base should spend the majority of their plyometric work focusing on reinforcing proper landing mechanics with activities like snap-downs and low drop landings. Small low-impact plyometrics such as various ankle hops, broad jumps, skips, push-offs, and low box jumps may also be appropriate in this training stage. After gaining sufficient strength and consistently demonstrating correct landing mechanics, the gymnasts can progress to medium and high-intensity plyometrics. For the upper body and core, med ball work serves as an extremely effective plyometric training method. Reverse med ball throws (seated for beginners, “granny” style or with an added jump for advanced), various chest passes, various slams (kneeling, ½ kneeling, isometric split squat, standing, with a jump) are all excellent choices. More advanced athletes (who have also reached physical maturity) may progress into loaded jumping exercises. In general, exercises are progressed from low intensity to higher intensity as the athlete demonstrates readiness and sufficient physical maturation to handle higher intensity plyometric strategies. Keep in mind that the most advanced high impact plyometric activities should be reserved for those who have reached physical maturity--those with open growth plates should be carefully progressed and monitored during plyometric training and high impact gymnastics skills [5]. When in doubt, coaches should err on the side of under-prescribing rather than over-prescribing in an effort to prevent injury in young athletes [6].

 

     It is wise not to have gymnasts perform high volumes of plyometrics without sufficient rest at any point. Still, the volume is decreased in an inverted relationship with the intensity of the exercises performed across the training year. Coaches can implement 1-3 days of direct plyometric training per week (depending on gymnast level and total training hours). Plan these days with skills practices in mind to avoid performing high-intensity plyometrics on top of high-intensity training days. High-intensity training days must be separated by sufficient recovery time. Within a single workout, rest intervals should be closely monitored to ensure that a work to rest ratio of 1:5 to 1:10 is observed, depending on the type of activity being performed. Measure foot contacts/impacts to control volume, and keep these numbers in line with the recommendations presented below. Remember that plyometric training exercises are power training, not conditioning or energy systems development! 

Review of the Relevant Plyometric Literature

     Plyometrics are an essential part of gymnastics training and performance and are commonly used to increase explosive power by way of the stretch-shortening cycle [1,11]. Preceding a concentric contraction with eccentric loading increases the force produced in the concentric phase. The pre-activation of the muscles receiving the stretch is directly related to the eccentric load applied [1,9]. Pre-activating the involved musculature to optimal stiffness before eccentric loading occurs facilitates energy storage in the muscles’ elastic components [9]. This pre-activation is a learned response [9],  further indicating the importance of including plyometric training in gymnastics conditioning programs.  

     Plyometric training (PT) facilitates beneficial adaptations in the sensorimotor system that are necessary for the development of strength and speed, thus enhancing athletic performance by improving neuromuscular function [1]. Plyometric training programs focused on the rate of force development improve vertical jumping and arm-leg coordination, peak power output, force development rate, and reduce ground reaction times [1,8,11]. PT and loaded jump training have also been shown to reduce the rate of severe knee injuries due to enhanced dynamic knee stability and increased mechanical efficiency of jumping through improved muscle activation patterning [1,11].

     In addition to accounting for lower extremity directionality, gymnastics plyometric training programs must include upper body plyometric training to account for the significant demands placed on the upper extremities in the sport [3,4]. It is ideal to include bodyweight based, gymnastics specific plyometric exercises for the upper body and standard upper body plyometric work such as medicine ball throws [3,14]. For the lower body, bodyweight jumping type exercises such as drop jumps, countermovement jumps, alternate leg bounding, and hopping are recommended [1,11]. Exercise selection should be specific to the movements in which increased force production is desired [1,11]. Training studies agreed that including PT 2 to 3 days per week with at least 48 hours between sessions led to significant jump performance increases [1,11]. Agostini et al. (2017) recommend beginning with low to moderate intensity with a focus on technical proficiency before gradually building up overload [1].

 

Landing Mechanics. Landing forces during gymnastics skills are estimated to be as high as 13-15x bodyweight [14]. Peak ground reaction forces during gymnastics landings were found to be 8.8-14.4 x bodyweight (vertical) [5], 5.3-8.8 x bodyweight (anterior-posterior), and 0.9-2.1 x bodyweight (medial-lateral) for each foot upon landing elite level gymnastics skills [10].  High landing forces paired with the shallow landings preferred by gymnastics scoring systems lead to an increased risk of ACL injuries [14] These shallow landings, combined with the lack of strength training standard in gymnastics, can result in the ligaments and joints absorbing these high forces rather than the active muscles [14]. In addition to the landing mechanics described here, it is common for gymnasts to possess knee strength imbalances in the form of relatively weak hamstrings compared to quadriceps muscle groups, leading to a higher incidence of ACL and knee injuries [7,12].  A large number of gymnastics knee and ankle injuries are sustained on twisting skills and dismounts from events, indicating that gymnasts struggle to satisfy both performance and safety objectives when attempting to land difficult skills without scoring deductions on landing [7]. Of note concerning injury risk in gymnastics: both the upper and lower extremities of gymnasts are subjected to frequent high impact, weight-bearing activities [7]. 

     Due to the high impact nature of gymnastics, athletes must learn to effectively and efficiently dissipate the massive amounts of force and moments the body is subjected to during landings and impacts [7]. When compared with recreational athletes, elite gymnasts changed their landing strategies to dissipate impact forces over a longer period as impact velocity increased [7]. Some researchers even suggest that changes to the gymnastics scoring system need to be made--de-emphasizing sticking landings--to reduce the impact forces imparted to the musculoskeletal system and reduce the number of ACL injuries [7].   To reduce injury rates, drop landings should be trained by gymnasts. This training can easily be included in regular plyometric training, and all plyometric training should be performed with an emphasis on proper landing mechanics. 

Combined Strength & Plyometric Training

     

     Implementing a combination of plyometric and strength training demonstrated many performance benefits in young female gymnasts [7]. The integration of heavy resistance training and high-velocity exercises was proven to be the optimal solution to elicit neuromuscular adaptation in both the stretch reflex and the rate of force development, demonstrating a strong synergistic effect [8,11]. The superior results of this combination training are theorized to be due to improved muscle tissue activation and synchronization of fiber recruitment [5,11]. The synchronized recruitment of more motor units would result in greater force development rapidly, increasing power output [5,11]. Training programs for these athletes should incorporate free-weight resistance training with compound exercises such as back squats, deadlifts, and power cleans in conjunction with plyometric drills like sprints, split squat jumps, variable height depth jumps and resisted jumping training [11]. The core of the resistance training program should include a unilateral and bilateral variety of squatting, horizontal and vertical pulling, horizontal and vertical pressing, hip hinging, plantar flexion and triple extension, and a variety of positional and dynamic exercises for the core. Exercise selection should encompass movements through all planes of motion. This training type should be incorporated 2 to 3 times per week, with 48 to 72 hours between sessions [8,11]. Training interventions with loading of 80 to 90% of 1RM and the maximal weight the gymnast could move for 8 to 12 repetitions both demonstrated significant improvements in strength, power, and jumping performance [8,11]. As athletes become more highly trained, the stimulus applied during conditioning must progressively increase to continue to overload the neuromuscular system and continue to generate adaptations to training [11].

References

  1. Agostini, B. R., Palomares, E. M. D. G., Andrade, R. D. A., Uchôa, F. N. M., & Alves, N. (2017). Analysis of the influence of plyometric training in improving the performance of athletes in rhythmic gymnastics. Motricidade, 13(2), 71-80.

  2. Bompa, T & Buzichelli, C. (2019). Periodization: Theory and Methodology of Training. Champaign, IL: Human Kinetics. 

  3. Chu, D. A. (1994). Strength exercises specific to gymnastics: a case study. The Journal of Strength and Conditioning Research, 8(2), 95-102. 

  4. Daly, R. M., Bass, S. L., & Finch, C. F. (2001). Balancing the risk of injury to gymnasts: how effective are the countermeasures?. British Journal of Sports Medicine, 35(1), 8-19. 

  5. Haff, G. G., & Triplett, N. T. (Eds.). (2015). Essentials of strength training and conditioning 4th edition. Human kinetics. 

  6. Lloyd, R. S., & Oliver, J. L. (Eds.). (2019). Strength and conditioning for young athletes: science and application. Routledge. 

  7. Marina, M., & Jemni, M. (2014). Plyometric training performance in elite-oriented prepubertal female gymnasts. The Journal of Strength and Conditioning Research, 28(4), 1015-1025. 

  8. Michel, M., Monèm, J., & Ferran, R. (2014). A two-season longitudinal follow-up study of jumps with added weights and countermovement jumps in well-trained pre-pubertal female gymnasts. Journal of Sports Medicine and Physical Fitness, 54(6), 730-741. 

  9. Mcneal, J. R., Sands, W. A., & Shultz, B. B. (2007). Muscle activation characteristics of tumbling take-offs. Sports Biomechanics, 6(3), 375-390.

  10. Panzer, Victoria & G.A.Wood, & Bates, Barry & Mason, Bruce. (1987). Lower Extremity Loads in Landings of Elite Gymnasts. 

  11. Ramírez-Campillo, R., Andrade, D. C., & Izquierdo, M. (2013). Effects of plyometric training volume and training surface on explosive strength. The Journal of Strength and Conditioning Research, 27(10), 2714-2722. 

  12. Rhea, M. R., Peterson, M. D., Oliverson, J. R., Ayllón, F. N., & Potenziano, B. J. (2008). An examination of training on the VertiMax resisted jumping device for improvements in lower body power in highly trained college athletes. The Journal of Strength and Conditioning Research, 22(3), 735-740. 

  13. Shinkle, J., Nesser, T. W., Demchak, T. J., & McMannus, D. M. (2012). Effect of core strength on the measure of power in the extremities. The Journal of Strength and Conditioning Research, 26(2), 373-380. 

  14. Tilley, D. (2018). Changing Gymnastics Culture: Reflections, Lessons, and Visions for the Future (1st ed.). Retrieved from https://shiftmovementscience.com/freeresourcelibrary/