Current thoughts on Plyometric Training
Fleck and Kraemer (2004:142) plyometric exercise is becoming a staple in the training regimens of all levels of athletes and coaches. Donatelli, (2006) defines plyometric as a quick, powerful movement involving pre-stretching or countermovement that activates the stretch
shortening cycle (SSC) of muscle. (Rimmer and Sleivert, 2000:294) plyometric exercises are characterized by an eccentric contraction immediately followed by a strong powerful concentric contraction of the muscle. (Donatelli, 2006) the purpose of plyometric conditioning is to heighten the excitability of the nervous system for improved reactive ability of neuromuscular system as a whole.
(Brewer C, 2005) plyometrics are a form of progressive resistance exercise (PRE) and thus, must follow the principles of progressive overload. Progressive overload is a systematic increase in frequency, volume, and intensity by various combinations of exercises. The method of progressive overload is dependent upon the sport and training phase. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels.
Chu and Myer, (2013) plyometric exercise has been recommended to bridge the gap between traditional rehabilitation exercises and sport-specific activities.
Contraindications for initiating plyometric exercise are acute inflammation or pain, immediate postoperative status, and joint instability. Paul et al, (2003) As
part of a comprehensive training program, plyometric exercise corrects neuromuscular imbalances that may predispose female athletes to injury, and several prospective studies have found that training programs that include plyometric exercise result in decreased lower extremity injury risk in female athletes. As effective as plyometrics can be for improving muscle springs, running economy, and speed, they can also derail training by making athletes more prone to injury. Injuries are likely caused by loss of tendon function near the muscle. Athletes should be aware that there is a risk of aggravating injury with plyometric exercises during rehabilitation. (Horrigan & Shaw,1989) are concerned that there are genuine factors for both athletes and coaches to consider before embarking on a plyometric training program. Spurrs, et al (2003) believes that as effective as plyometrics can be for improving muscle springs, running economy, and speed, they can also derail training by making athletes more prone to injury. Adams, et al (1992) implies that plyometric training does carry a high injury risk due to its explosive nature; this however is dated statement with current research contradicting this.
Plyometric training can vary in intensity (low, medium, or high) dependant on the athlete’s ability and the specific exercises being performed, (Ebben, 2003). Low intensity plyometric drills would be jump drills. Moderate intensity would include drills such as short-response hops, long-response hops, or combination jumps. Combination jumps are low-intensity jumps combined in a continuous pattern. High-intensity plyometrics are very advanced and should not be considered until
after 6 weeks of low and moderate intensity drills have been accomplished, (Baechle and Earle, 2000). Examples of high-intensity drills are shocks, power jumps, and single leg hops. Shock jumps include in-depth jumps, box jumps, and drop-and-catch push-ups.
Strength and conditioning professionals have documented that plyometrics have been fundamental in the development of power for athletes at all levels. (Ebben W, 2002) the combination of plyometric training and weight training are thought to be useful for developing athletic power. An independent study by (Adams et
al,1992) demonstrates an enhancement of motor performance associated with plyometric training combined with weight training or the superiority of
plyometrics, compared to other methods of training (Wilson G, et al., 1996) Athletes who perform both heavy weight training and plyometric exercises maenhance the use of elastic strain energy and facilitate the stretch reflex to a greater extent than does maximal power training. Research from strength and conditioning professionals relating to plyometric training, emphasizes the benefits for developing power mainly in the lower body. Chu and Myer, (2013) suggests that plyometric training improves neuromuscular function, including joint position sense (proprioception) and postural control. In a series of studies conducted from 2004 to 2006, Myer et al showed that plyometric work improved postural stability in single leg stance: trunk stability when landing from a jump; and biomechanical measures relevant to lower limb injury risk. Swanik et al (2002) found that upper limb plyometric training improved joint position sense. The key training principle of specificity dictates that training for a sport should replicate the movement patterns and energy systems required for that sport. The crucial judgement for therapists lies in what level of activity to introduce at what point in the rehab process. Low intensity plyometrics is useful tool to retain dynamic balance and proprioception after injury and once functional stability is regained, such exercises can be gradually introduced. In late stage of rehabilitation, when the injury site is strong and close to fully repaired, higher level plyometric drills that mimic the sporting environment may be included. It is essential that recovering athletes perform explosive type movements in a closed environment before returning to any field or court sport.
(Chmielewski, et al., 2006) The majority of the literature related to muscle-tendon unit physiology during stretch-shortening exercise, and documenting performance gains and positive adaptations in neuromuscular function after plyometric training, applies to the lower extremity. One of the most glaring disparities in the research on plyometric exercise is the scarcity of studies pertaining to the upper extremity and trunk. (Swanik K. et al., 2002) with regard to the effect of plyometric training on upper extremity muscle performance, there is substantially less literature. This may be due to plyometric exercises showing great results for the lower extremities as all sports requires movement from the lower body. However there is some research on the benefits of plyometric training for the upper body with new exercises coming to light however the majority of research suggests that plyometric training is mostly used for improving athletes power in lower extremities.
Because plyometric exercises mimic the motions used in sports such as skiing, tennis, football, basketball, volleyball, rugby and boxing, plyometric training is often used to condition professionals and amateur adult athletes Donald, (2013). Recent research by Donald, (2013) suggests that children and adolescents can also benefit from a properly designed and supervised plyometric routine, according to the American College of Sports Medicine. Moderate jumps (low intensity) can be included in the athletic training of very young children Avery (2006). However, great care needs to undertake when prescribing any training procedures for preadolescent children. Because of the relatively immature bone structure in preadolescent and adolescent children the very great forces exerted during intensive depth jumps (high intensity) should be avoided (Ebben, 2003).
CONCLUSION
Current literature emphasizes the benefits of plyometric training for improving power. Majority of the literature refers to the benefits of plyometric for athletes however there has also been evidence of low intensity plyometric training being performed by young adolescents. Plyometric training has been found to be beneficial for the lower extremity of the body, however little research seems to be available on plyometrics benefits on the upper extremity. This is an area where there is potential for further research to be undertaken.
In the past, plyometrics, particularly high intensity exercises, have not been seen as an important part of rehabilitation, probably because of the associated risk an decreased emphasis on exercise based therapy. However, modality is sound in principal and essential in practice to the success of late stage rehabilitation. As long as the exercise is mimicking the sporting activity and are confident that the athletes injury can withstand it physiologically, embrace it.
Refernce List
Adams K, O’Shea, et al. (1992). ‘The effect of six weeks of squat, plyometric and squat plyometric training on power production’. Journal of Applied Sport Science Res. No.6: 36-41
Baechle, T. and Earle, R. (200) Essentials of Strength Training and Conditioning. (3rd ed.) Leeds: Human Kinetics.
Brewer, C. (2005) A perspective on…Plyometrics. [Online] Available from: http://www.uksca.org.uk/uksca/RelatedFiles/Plyometrics.pdf [accessed 31 March
2014]
Chmielewski, T., Myer, G., Kauffman, D. and Tillman, S. (2006) Plyometric Exercise in the Rehabilitation of Athletes: Physiological Responses and Clinical Application. Journal of Orthopaedic & Sports Physical Therapy. Vol. 36, No. 5: 308-319.
Chu, D. and Myer, G. (2013) Plyometrics. (1st ed.) Leeds: Human Kinetics.
Donatelli, R. (2006) Sports-specific Rehabilitation. (1st ed.) MIssouri: Elsevier Health Sciences.
Ebben, W. (2002) COMPLEX TRAINING: A BRIEF REVIEW. Journal of Sports Science and Medicine. Vol. 1, No. 1: 46.
Ebben, W. (2003) Practical Guidelines for Plyometric Intensity. NSCA’s Performance Training Journal. Vol. 6, No. 5: 38.
Fleck, S. and Kraemer, W. (2004) Designing Resistance Training Programmes. (3rd ed.) Leeds: Human Kinetics.
Rimmer E, Sleivert G.(2000) ‘Effects of plyometric intervention program on sprint performance’. Journal of Strength Conditioning Res. No. 14: 295-301
Wilson, G., Murphy, A. and Giorgi , A. (1996) Weight and Plyometric Training: Effects on Eccentric and Concentric Force Production. Canadian Journal of Applied Physiology. Vol. 21, No. 4: 301-315.
Spurrs R, Murphy A, Watsford M. (2003) ‘The effect of plyometric training on distance running performance’. European Journal of Applied Physiology. No. 89: 1-7
Swanik, K., Lephart, S., Swanik, B. and Lephart, S. (2002) The effects of shoulder plyometric training on proprioception.. J Shoulder Elbow Surg. Vol. 11, No. 6: 579-586.
shortening cycle (SSC) of muscle. (Rimmer and Sleivert, 2000:294) plyometric exercises are characterized by an eccentric contraction immediately followed by a strong powerful concentric contraction of the muscle. (Donatelli, 2006) the purpose of plyometric conditioning is to heighten the excitability of the nervous system for improved reactive ability of neuromuscular system as a whole.
(Brewer C, 2005) plyometrics are a form of progressive resistance exercise (PRE) and thus, must follow the principles of progressive overload. Progressive overload is a systematic increase in frequency, volume, and intensity by various combinations of exercises. The method of progressive overload is dependent upon the sport and training phase. Plyometric exercises are initiated at a lower intensity and progressed to more difficult, higher intensity levels.
Chu and Myer, (2013) plyometric exercise has been recommended to bridge the gap between traditional rehabilitation exercises and sport-specific activities.
Contraindications for initiating plyometric exercise are acute inflammation or pain, immediate postoperative status, and joint instability. Paul et al, (2003) As
part of a comprehensive training program, plyometric exercise corrects neuromuscular imbalances that may predispose female athletes to injury, and several prospective studies have found that training programs that include plyometric exercise result in decreased lower extremity injury risk in female athletes. As effective as plyometrics can be for improving muscle springs, running economy, and speed, they can also derail training by making athletes more prone to injury. Injuries are likely caused by loss of tendon function near the muscle. Athletes should be aware that there is a risk of aggravating injury with plyometric exercises during rehabilitation. (Horrigan & Shaw,1989) are concerned that there are genuine factors for both athletes and coaches to consider before embarking on a plyometric training program. Spurrs, et al (2003) believes that as effective as plyometrics can be for improving muscle springs, running economy, and speed, they can also derail training by making athletes more prone to injury. Adams, et al (1992) implies that plyometric training does carry a high injury risk due to its explosive nature; this however is dated statement with current research contradicting this.
Plyometric training can vary in intensity (low, medium, or high) dependant on the athlete’s ability and the specific exercises being performed, (Ebben, 2003). Low intensity plyometric drills would be jump drills. Moderate intensity would include drills such as short-response hops, long-response hops, or combination jumps. Combination jumps are low-intensity jumps combined in a continuous pattern. High-intensity plyometrics are very advanced and should not be considered until
after 6 weeks of low and moderate intensity drills have been accomplished, (Baechle and Earle, 2000). Examples of high-intensity drills are shocks, power jumps, and single leg hops. Shock jumps include in-depth jumps, box jumps, and drop-and-catch push-ups.
Strength and conditioning professionals have documented that plyometrics have been fundamental in the development of power for athletes at all levels. (Ebben W, 2002) the combination of plyometric training and weight training are thought to be useful for developing athletic power. An independent study by (Adams et
al,1992) demonstrates an enhancement of motor performance associated with plyometric training combined with weight training or the superiority of
plyometrics, compared to other methods of training (Wilson G, et al., 1996) Athletes who perform both heavy weight training and plyometric exercises maenhance the use of elastic strain energy and facilitate the stretch reflex to a greater extent than does maximal power training. Research from strength and conditioning professionals relating to plyometric training, emphasizes the benefits for developing power mainly in the lower body. Chu and Myer, (2013) suggests that plyometric training improves neuromuscular function, including joint position sense (proprioception) and postural control. In a series of studies conducted from 2004 to 2006, Myer et al showed that plyometric work improved postural stability in single leg stance: trunk stability when landing from a jump; and biomechanical measures relevant to lower limb injury risk. Swanik et al (2002) found that upper limb plyometric training improved joint position sense. The key training principle of specificity dictates that training for a sport should replicate the movement patterns and energy systems required for that sport. The crucial judgement for therapists lies in what level of activity to introduce at what point in the rehab process. Low intensity plyometrics is useful tool to retain dynamic balance and proprioception after injury and once functional stability is regained, such exercises can be gradually introduced. In late stage of rehabilitation, when the injury site is strong and close to fully repaired, higher level plyometric drills that mimic the sporting environment may be included. It is essential that recovering athletes perform explosive type movements in a closed environment before returning to any field or court sport.
(Chmielewski, et al., 2006) The majority of the literature related to muscle-tendon unit physiology during stretch-shortening exercise, and documenting performance gains and positive adaptations in neuromuscular function after plyometric training, applies to the lower extremity. One of the most glaring disparities in the research on plyometric exercise is the scarcity of studies pertaining to the upper extremity and trunk. (Swanik K. et al., 2002) with regard to the effect of plyometric training on upper extremity muscle performance, there is substantially less literature. This may be due to plyometric exercises showing great results for the lower extremities as all sports requires movement from the lower body. However there is some research on the benefits of plyometric training for the upper body with new exercises coming to light however the majority of research suggests that plyometric training is mostly used for improving athletes power in lower extremities.
Because plyometric exercises mimic the motions used in sports such as skiing, tennis, football, basketball, volleyball, rugby and boxing, plyometric training is often used to condition professionals and amateur adult athletes Donald, (2013). Recent research by Donald, (2013) suggests that children and adolescents can also benefit from a properly designed and supervised plyometric routine, according to the American College of Sports Medicine. Moderate jumps (low intensity) can be included in the athletic training of very young children Avery (2006). However, great care needs to undertake when prescribing any training procedures for preadolescent children. Because of the relatively immature bone structure in preadolescent and adolescent children the very great forces exerted during intensive depth jumps (high intensity) should be avoided (Ebben, 2003).
CONCLUSION
Current literature emphasizes the benefits of plyometric training for improving power. Majority of the literature refers to the benefits of plyometric for athletes however there has also been evidence of low intensity plyometric training being performed by young adolescents. Plyometric training has been found to be beneficial for the lower extremity of the body, however little research seems to be available on plyometrics benefits on the upper extremity. This is an area where there is potential for further research to be undertaken.
In the past, plyometrics, particularly high intensity exercises, have not been seen as an important part of rehabilitation, probably because of the associated risk an decreased emphasis on exercise based therapy. However, modality is sound in principal and essential in practice to the success of late stage rehabilitation. As long as the exercise is mimicking the sporting activity and are confident that the athletes injury can withstand it physiologically, embrace it.
Refernce List
Adams K, O’Shea, et al. (1992). ‘The effect of six weeks of squat, plyometric and squat plyometric training on power production’. Journal of Applied Sport Science Res. No.6: 36-41
Baechle, T. and Earle, R. (200) Essentials of Strength Training and Conditioning. (3rd ed.) Leeds: Human Kinetics.
Brewer, C. (2005) A perspective on…Plyometrics. [Online] Available from: http://www.uksca.org.uk/uksca/RelatedFiles/Plyometrics.pdf [accessed 31 March
2014]
Chmielewski, T., Myer, G., Kauffman, D. and Tillman, S. (2006) Plyometric Exercise in the Rehabilitation of Athletes: Physiological Responses and Clinical Application. Journal of Orthopaedic & Sports Physical Therapy. Vol. 36, No. 5: 308-319.
Chu, D. and Myer, G. (2013) Plyometrics. (1st ed.) Leeds: Human Kinetics.
Donatelli, R. (2006) Sports-specific Rehabilitation. (1st ed.) MIssouri: Elsevier Health Sciences.
Ebben, W. (2002) COMPLEX TRAINING: A BRIEF REVIEW. Journal of Sports Science and Medicine. Vol. 1, No. 1: 46.
Ebben, W. (2003) Practical Guidelines for Plyometric Intensity. NSCA’s Performance Training Journal. Vol. 6, No. 5: 38.
Fleck, S. and Kraemer, W. (2004) Designing Resistance Training Programmes. (3rd ed.) Leeds: Human Kinetics.
Rimmer E, Sleivert G.(2000) ‘Effects of plyometric intervention program on sprint performance’. Journal of Strength Conditioning Res. No. 14: 295-301
Wilson, G., Murphy, A. and Giorgi , A. (1996) Weight and Plyometric Training: Effects on Eccentric and Concentric Force Production. Canadian Journal of Applied Physiology. Vol. 21, No. 4: 301-315.
Spurrs R, Murphy A, Watsford M. (2003) ‘The effect of plyometric training on distance running performance’. European Journal of Applied Physiology. No. 89: 1-7
Swanik, K., Lephart, S., Swanik, B. and Lephart, S. (2002) The effects of shoulder plyometric training on proprioception.. J Shoulder Elbow Surg. Vol. 11, No. 6: 579-586.