Eccentric Training for Tendinopathy Injuries:
Eccentric training is a form of training in which the muscle is worked as it lengthens. In contrast, concentric training involves a muscle working as it shortens. A good example of these can be observed within a bicep curl – as the elbow bends the biceps work concentrically and the muscles shorten as they work. However, as the elbow then straightens the bicep muscles are lengthening, but they continue to contract and work as they control the movement.
It has been found that the faster a muscle contracts concentrically (shortening), the lower the tension it is able to generate (1). Tension in muscle fibres when lengthening (eccentric) is considerably greater than when muscle fibres are shortening (2).
Previous studies have shown that when a muscle is eccentrically lengthened, the energy requirement falls substantially in comparison to concentric contractions because ATP breakdown and heat production are both slowed (2). Furthermore, with increased heat generation during concentric work, there is a concurrent increase in cellular metabolism. Thus, more waste products will be generated with concentric work, potentially leading to chemical irritation of nerves and eventually pain (6).
Tendons are the extremities of a muscle that attaches to bone and injury to tendons can occur from sudden trauma, overuse or repetitive strain. Tendon injuries account for 30-50% of injuries in sports (4). Specifically, chronic problems caused by overuse of tendons result in 30% of all running-related injuries, and elbow tendon injuries can be as high as 40% in tennis players (8). Incidence of patellar tendonopathy is reported to be as high as 32% and 45% in basketball and volleyball players, respectively (5). It is therefore important to quickly diagnose and treat such injuries with physiotherapy.
Eccentric training for tendinopathies
The Alfredson et al (1) protocol has frequently been used since its production in 1998 and appears to be a safe, effective method of implementing the eccentric training program for tendinopathies. However, this protocol was produced for and used in the treatment of achilles tendinopathies and their exact recommendations may not be appropriate for all tendons or regions.
The Alfredson protocol used three sets of 15 repetitions of bent knee and straight knee calf raises, twice a day, seven days per week over 12 weeks. Athletes were told to work through pain, only ceasing exercise if pain became disabling. Training load was increased in 5 kg increments with use of a backpack that allowed for the addition of the weight once training with bodyweight was pain free. The eccentric phase of the exercise should be performed relatively slowly, counting to 3-4 seconds as you complete the movement. The concentric phase should be avoided and the other limb can return you to the starting position of the exercise.
All of the subjects within the initial study (1) who used this protocol, returned to pre-injury activity levels and found a significant decrease in pain with a significant increase in strength.
According to Lorenz & Reiman (6), the physiotherapist may use the Alfredson protocol for an example of volume and frequency of training, but addition of weights and resistance should be dictated by the amount of pain experienced by the individual, and the exercises should be dictated by a physiotherapist to ensure correct technique and suitability of exercises.
Curwin (3) has also proposed a method to determine training load in eccentric training for tendon injuries. One significant difference between Curwin’s and Alfredson’s programs is that the athlete performs both the concentric and eccentric portion of the exercise in Curwin’s program, with the eccentric portion being performed faster. In Curwin’s protocol, they suggest that the athlete should experience pain and fatigue between 20 and 30 repetitions at a given load, when performing three sets of 10 repetitions.
Their rationale for experiencing pain is based on the premise that exercise load should be determined by the tendon tolerance, which is indicated by pain experienced during the exercise. If there is no pain after 30 repetitions, the stimulus is inadequate. Either load or the speed of exercise performance should be increased, but not both simultaneously.
Based on the clinical experience of the authors and others (7), it is recommended that 6-12 repetitions over four sets be completed to emphasize strength in the muscle-tendon complex. The athletes use the load from the six repetition resistance and build up to twelve repetitions prior to increasing load again. This process helps to maintain safe and progressive eccentric training. Additionally, the authors advocate three to four sessions per week instead of every day.
Lorenz & Reiman (6) suggest that the physiotherapist or athlete do not perform the concentric portion of the exercise or perform it with the assistance of the uninvolved limb, followed by having the athlete perform the eccentric portion of the exercise independently. Based on clinical experience, the concentric portion of the exercise can be attempted without assistance once non-sport/day-to-day activities, like walking, stair climbing and washing, are pain free.
As with eccentric exercise, progression of the concentric portion of exercise should involve a gradual increase. Once the concentric portion of exercise is pain free, the athletes can begin jogging or more sport specific activities.
1. Alfredson H, Pietila T, Jonsson P, & Lorentzon R. (1998) Heavy-load eccentric calf muscle training for treatment of chronic Achilles tendinosis. Am J Sports Med. 26: 360-366.
2. Curtin N A & Davies R E. (1970) Chemical and mechanical changes during stretching of activated frog muscle. Cold Spring Harb Symp Quant Biol. 37: 619-626.
3. Curwin S L. (1996) Tendon injuries: Pathophysiology and treatment. In: Athletic Injuries and Rehabilitation. J Zachazewski, DJ Magee, WS Quillen, ed. Philadelphia, PA: WB Saunders Co. 27-54.
4. Khan K M & Scott A. (2009) Mechanotherapy: how physical therapists’ prescription of exercise promotes tissue repair. Br J Sports Med. 43: 247-251.
5. Lian O B, Engebretsen L & Bahr R. (2005) Prevalence of jumper’s knee among elite athletes from different sports: a cross-sectional study. Am J Sports Med. 33: 561-567.
6.Lorenz D & Reiman M. (2011) The role and implementation of eccentric training in athletic rehabilitation: Tendinopathy, hamstring strains, and acl reconstruction. International Journal of Sports Physical Therapy 6(1): 27-44.
7. Ratamess N A, Alvar B A, Evetoch T K, et al. (2009) Progression models in resistance training for healthy adults: ACSM Position Stand. Med Sci Sports Exerc. 41(3): 687-708.
8 Sharma P & Maffulli N. (2006) Biology of tendon injury: healing, modeling, and remodeling. J Musculoskelet Neuronal Interact. 6: 181-190.
Blog produced by www.jbphysio.co.uk and re-produced with permission via twitter