Plyometrics for Runners

Ky Wynne is a Physiotherapist & Exercise Scientist with a professional interest in running injuries and exercise rehabilitation. Ky currently consults out of a large multidisciplinary sports medicine private practice in Melbourne, and has experience working with a range of sports including soccer & football. He has a strong passion for continued learning, and also enjoys giving back, presenting sessional lectures at Swinburne University, delivering personal development in services, and presentations at other organizations including the APA. Ky runs an evidence-based physiotherapy and S&C blog through his website, along with a social media channel on Instagram.
Website: www.kywynne.com/blog
Instagram: www.instagram.com/kywynnephysio

WHAT ARE PLYOMETRICS?
 

Plyometrics are rapid, powerful and dynamic movements. These exercises involve a rapid stretching and subsequent contraction of the muscles, with the purpose of developing a forceful or powerful movement in a short window of time. These movements work via neural and musculoskeletal pathways (1, 2, 3, 4, 5, 6).

Plyometrics are often used by trainers, coaches, health professionals and athletes for development of power (3, 7, 8). It is recommended that plyometrics should form a crucial component of performance and rehabilitation programs. Furthermore, this form of training is often considered the vital link between rehab and return to performance (7). Plyometrics have also been considered a bridge between strength and speed (5). Examples of plyometric activities in the lower extremities include running, sprinting, jumping, hopping, bounding, kicking and other powerful movements (1, 2, 5, 6, 7, 8).

The use of plyometrics and maximal power training allows the athlete to stimulate high velocity movements without a deceleration phase associated with heavier/strength-style training (9). The figure (see figure 2) shows the components of force and velocity trained during differing methods. Plyometrics aim to increase the amount of force that can be exerted at high movement speeds (9). Figure-3 shows an example of a force-velocity curve. Plyometric and power training work at the upper end of the velocity component, whilst strength training often works much closer the higher ends of the force component of the cure.

 
Figure-2, sourced from Ebben, 2001.

Figure-3 from ref 10.

Plyometrics: Mechanism
Plyometric training exaggerates the stretch-shortening cycle (SSC), utilizing a lengthening movement (eccentric) which is quickly followed by a shortening movement (concentric) (1, 4, 5, 7). The SSC is the successive combination of eccentric (ECC) and concentric (CON) muscle actions, with the combined CON and ECC actions generating forces that are greater than a CON contraction in isolation (11, 12). The combined ECC and CON actions are common in most sporting and athletic activities (11). The plyometric movements utilize both the natural elastic components of muscles, along with the tendon stretch reflex (5). The SSC during running significantly aids movement economy. Without the elastic energy storage contribution, runners would experience a significant increase (30-40%) in oxygen consumption (13).

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Eccentric pre-stretch phase:
•    Pre-stretch phase will enhance resultant concentric muscle contraction
•    This “stretch” phase allows storage of tension/elastic energy
•    Important variables: can manipulate to effect the exercise outcomes. These variables impact on the amount of energy stored during the pre-stretch phase. - Magnitude of stretch - Rate of the stretch - Duration of the stretch

Amortization: 
•    This is the time from cessation of eccentric pre-stretch to the onset of concentric muscle action.
•    Also known as the “time to rebound”, where there is a delay between overcoming the negative work of eccentric pre-stretch and generating force production, acceleration and elastic recoil.
•    Key: - A shorter amortization phase leads to a more effective and plyometric movement. This is due to stord energy being used more efficiently in transition. - A slow, or delayed amortization phase means stored energy is wasted.
•    One of the primary goals of plyometric training is to decrease the amortization phase. Important: Want quick/short ground contact times during plyometric movements.

Concentric Phase:
•    The resultant power production performance phase.
•    Results from many interactions, including the biomechanical response that utilizes the elastic properties of the pre-stretched muscles.
(3, 7).

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Figure-4. Benefits of plyometric training.

•    Plyometric training improves power generation (4, 7)
•    Plyometrics also increases the stiffness of the muscle-tendon system (1, 4). - This allows greater and more effective storage and utilization of elastic energy, with this leading to decreased energy expenditure and ground contact time (1, 4)
•    Improved endurance running performance (14, 15, 16, 17)
•    Improved running economy (oxygen cost of running) (1, 2, 4, 14, 15, 17) - Muscles are able to generate more force without a proportionate increase in metabolic energy requirement (4)
•    Increased sprinting speed (5, 6, 7, 8, 16, 17)
•    Improved acceleration (8)
•    Improved jump power and ability (5, 15, 16, 17)
•    Improved agility performance (5)
•    Increased bone mass and remodelling (5, 9)
•    Improved connective tissue strength (9)
•    Increased eccentric muscle strength (9)
•    Beneficial in youth athletes (5)
•    Possible reduced injury risk in sports (5)

Plyometrics for Running: Overview
Running is a dynamic, high speed activity involving single leg bounding/hopping-type movements (9). It is recommended to attempt to replicate the strength, movement and speed demands of your sport in training (9). Plyometric training more closely mimics the specificity of running than slow speed strength training, with short ground contact times. Resistance training is also a crucial part of a running training program, however is not the focus of this article. 

One of the major benefits of plyometrics on running performance is through the be the improvement it elicits in running economy. Running economy is defined as the steady-state oxygen requirement for a given submaximal running speed, or simple, the oxygen cost of running (15, 18, 19). The improvements in running economy lead to a runner expending less energy or oxygen consumption at a given running speed (14). Running economy has been shown to relate strongly to running performance (14, 15, 17, 18).

It has been speculated that runners with poor economy may have a reduced ability for their musculotendinous system to store and utilized the energy produced during the eccentric components of running (15, 20, 21). The exact mechanisms that plyometric improve running economy are unknown, it is thought that increased musculotendinous stiffness allows the body to store and utilize elastic energy more effectively (4, 13, 14). It is also thought that improvements in movement and running technique, muscle strength & power, and neural mechanisms contribute to improved running economy following plyometrics (1, 4).

Assessment/Minimum Competencies:

Figure-5. Sourced from (7).

Prior to undertaking a plyometrics program it is recommended to have an assessment with a trained medical professional. You need to possess minimum levels of strength and movement control to allow a safe completion of the program without significant injury risk (7). If you or your athlete doesn’t regularly train strength or plyometrics movements, it is recommended to perform a strength cycle prior to commencing plyometrics (e.g. 6-12 weeks) (9). There are some general considerations to evaluate prior to commencement (see figure-5). Furthermore, assessment of the athlete’s age, injury history, types of injuries, warm ups, foundation strength and resistance training experience are critical (7). Consider planning and preparing the plyometric sessions, along with adequate progressions to allow load management (5). Finally, it is always important to master technique prior to adding speed, complexity or load (5). Athletes may need familiarization sessions prior to commencing the program.

FITT:
Below is an evidence-based summary of FITT principles for lower limb plyometrics (1, 3, 5, 7, 9).

Frequency: Every 2-3 days
•    Per week: 2 x week recommended
•    Recovery: 48-72 hours recovery needed between sessions
•    Duration: Continue for between 3-12 weeks (6-12 weeks recommended)
Intensity: Between 80-300 foot contacts, depending on the athlete’s ability and exercise difficulty. Figure-6 shows an example of beginner, intermediate and advanced foot contact per session.
•    3-4 exercises
•    2-6 sets
•    5-20 jumps per exercise
 

Figure-6. Examples of intensities for plyometric exercises (7).

Note: gradual progression of exercise intensity is recommended
Time: 10-25minutes
•    Ideally completed at the start or pre-session (e.g. pre running, pre sports training, pre weights training but after a warm up).
Type: Variety of jumping, skipping, bounding movements. These include running drills, along with box jumps. Recommended to combine vertical and horizontal jumps. See the figure (figure-7) below for more examples of easy, moderate and hard levels. Recommended to consider running movements to make the exercises specific. Furthermore, incorporate single leg exercises (when physical capacity allows) where possible due to the unilateral nature of running. Remember, technique must be mastered before progression.

Note: gradual progression of exercise difficulty is recommended.
 

Figure-7. Examples of lower limb plyometric exercises (7).

RESEARCH STUDIES
Plyometric training has been shown elicit significant improvements in running performance (2.6-3.9%), running economy (up to 8.1%) and sprint times (2.3-3.4%). Whilst these numbers may seem small, an ~3% improvement in your 3km running time could be significant. E.g. 3kms @ 5:00min/km pace = 15minutes. A 3% improvement = 45seconds (pace of 4:45min/km). The following examples highlight some of the research papers looking at plyometrics and running.
Example 1: (Pellegrino et al., 2016)
•    Subjects: recreational runners.
•    Program: Progressive 6 week program, completing 15 sessions, with foot contacts increasing from 60-228.
•    Result: The program provided a 2.6% increase in 3km time trial and improved running economy compared to controls.
Example 2: (Spurrs et al., 2003)
•    Subjects: recreational runners.
•    Program: Progressive 6 week program, completing 2-3 sessions per week, with foot contacts increasing from 60-180.
•    Result: The program provided a 2.7% increase in 3km time trial and improved running economy compared to controls.
Example 3: (Paavolainen et al., 1999)
•    Subjects: elite cross country runners.
•    Program: Progressive 9 week program, completing 15 sessions, with foot contacts ranging between 30-200.
•    Result: The program provided a 3.1% increase in 5km time trial and 8.1% increase in running economy compared to controls. Improved 20m sprint time (3.4%) and jump power (4.6%).
Example 4: (Rimmer & Sleivert, 2000)
•    Subjects: recreational rugby players.
•    Program: Progressive 8 week program, completing 15 sessions, with foot contacts increasing from 80-160.
•    Result: Improved 10m and 40m sprint time. Increase was greatest during the initial 10m (acceleration phase). Improvements were similar to a sprint training program, thus recommended to include both.
Example 5: (Singh & Singh, 2013)
•    Subjects: male students.
•    Program: Progressive 10 week program, completing 20 sessions, with foot contacts approximately 60 per session. Compared between vertical jumps, horizontal jumps, combined vertical and horizontal.
•    Result: Improved 40 metre sprint time for all groups (vertical, horizontal and combined). Horizontal and combined groups produced superior results comparted to vertical.
Example 6: (Ramírez-Campillo et al., 2014)
•    Subjects: moderately trained male runners
•    Program: 6 week program, completing 12 sessions, with foot contacts consisting of 60 per session.
•    Result: Improved 2.4km time trial (3.9%) and 20m sprint time (2.3%). Also improvements in jump power.

PLYOMETRIC EXAMPLES FOR RUNNERS
51%
 

Video here: Link = https://www.youtube.com/watch?v=de4xHxfohu8&

CONSIDER
Thank you for reading. Hopefully you have learned something that you can implement yourself, or with your patients/athletes/runners. If you have any questions, please don't hesitate to get in contact. Furthermore, if you're a runner looking for an assessment, or a plyometric program put together specific for you and your current level, send me an email or message.

RESOURCES
•    Davies et al., 2015: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4637913/
•    The Ultimate Guide To Plyometrics (Trust Me-Ed) by Mitchell Casey: https://www.trustme-ed.com/blog/the-ultimate-guide-to-plyometrics
•    Bedoya, A. A., Miltenberger, M. R., & Lopez, R. M. (2015). Plyometric training effects on athletic performance in youth soccer athletes: a systematic review. The Journal of Strength & Conditioning Research, 29(8), 2351-2360.

REFERENCES
1. Barnes, K. R., & Kilding, A. E. (2015). Strategies to improve running economy. Sports medicine, 45(1), 37-56.
2. Turner, A. M., Owings, M., & Schwane, J. A. (2003). Improvement in running economy after 6 weeks of plyometric training. The Journal of Strength & Conditioning Research, 17(1), 60-67.
3. Singh, D., & Singh, S. (2013). Effects of vertical and horizontal plyometric exercises on running speed. Human movement, 14(2), 144-147.
4. Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004). Factors affecting running economy in trained distance runners. Sports medicine, 34(7), 465-485.
5. Bedoya, A. A., Miltenberger, M. R., & Lopez, R. M. (2015). Plyometric training effects on athletic performance in youth soccer athletes: a systematic review. The Journal of Strength & Conditioning Research, 29(8), 2351-2360.
6. Young, W. B. (2006). Transfer of strength and power training to sports performance. International journal of sports physiology and performance, 1(2), 74-83.
7. Davies, G., Riemann, B. L., & Manske, R. (2015). Current concepts of plyometric exercise. International journal of sports physical therapy, 10(6), 760.
8. Rimmer, E., & Sleivert, G. (2000). Effects of a plyometrics intervention program on sprint performance. The Journal of Strength & Conditioning Research, 14(3), 295-301.
9. Ebben, W. P. (2001). Maximum power training and plyometrics for cross-country running. Strength & Conditioning Journal, 23(5), 47.
10. Figure sourced from: https://www.trainwithpush.com/blog/want-to-get-the-most-out-of-your-training-get-ahead-of-the-curve-the-force-velocity-curve-that-is.
11. Cormie, P., McGUIGAN, M. R., & Newton, R. U. (2010). Changes in the eccentric phase contribute to improved stretch-shorten cycle performance after training. Medicine & Science in Sports & Exercise, 42(9), 1731-1744.
12. Walshe, A. D., Wilson, G. J., & Ettema, G. J. (1998). Stretch-shorten cycle compared with isometric preload: contributions to enhanced muscular performance. Journal of Applied Physiology, 84(1), 97-106.
13. Lum, D., Tan, F., Pang, J., & Barbosa, T. M. (2019). Effects of intermittent sprint and plyometric training on endurance running performance. Journal of sport and health science, 8(5), 471-477.
14. Pellegrino, J., Ruby, B. C., & Dumke, C. L. (2016). Effect of plyometrics on the energy cost of running and MHC and titin isoforms. Medicine & Science in Sports & Exercise, 48(1), 49-56.
15. Spurrs, R. W., Murphy, A. J., & Watsford, M. L. (2003). The effect of plyometric training on distance running performance. European journal of applied physiology, 89(1), 1-7.
16. Ramírez-Campillo, R., Álvarez, C., Henríquez-Olguín, C., Baez, E. B., Martínez, C., Andrade, D. C., & Izquierdo, M. (2014). Effects of plyometric training on endurance and explosive strength performance in competitive middle-and long-distance runners. The Journal of Strength & Conditioning Research, 28(1), 97-104.
17. Paavolainen, L., Hakkinen, K., Hamalainen, I., Nummela, A., & Rusko, H. (1999). Explosive-strength training improves 5-km running time by improving running economy and muscle power. Journal of applied physiology, 86(5), 1527-1533.
18. Morgan, D. W., Martin, P. E., & Krahenbuhl, G. S. (1989). Factors affecting running economy. Sports Med, 7(5), 310-330.
19. Conley, D. L., Krahenbuhl, G. S., & Burkett, L. N. (1981). Training for aerobic capacity and running economy. The Physician and sportsmedicine, 9(4), 107-146.
20. Noakes T (1991) Lore of running. Leisure Press, Champaign, Ill.
21. Wilson, G. J., Wood, G. A., & Elliott, B. C. (1991). Optimal stiffness of series elastic component in a stretch-shorten cycle activity. Journal of applied physiology, 70(2), 825-833.

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