Eccentric exercise techniques are now being used by physical therapists to manage a host of conditions, such as tendinopathy, muscle strains and ACL rehabilitation. This is largely because it is well known that eccentric exercise results in less oxygen consumption, greater force production and less energy expenditure than concentric exercise, which constitutes the majority of strength training that takes place in gyms worldwide.
Tendon injuries account for 30-50% of injuries in sports.
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. About 7-9% of professional athletes, for example, suffer from Achilles tendinopathy and 6-18% of all injuries in recreational running relate to the Achilles.
The incidence of patellar tendinopathy is reported to be as high as 32% and 45% in basketball and volleyball players, respectively. Tendon pathologies not only lead to lost time and performance declines in sports but also can result in long-term damage to tendons that can affect daily function.
Studies have shown that the use of eccentric training can reduce pain and improve strength in patients with tendinopathies.
Hamstring strains are among the most common injuries sustained by athletes.
Hamstring muscle strains are currently the most common injury in professional soccer, and they account for around 30% of injuries in track and field sprinters. A number of studies have concluded that the use of eccentric training as part of recovery may lead to both improved outcomes and the decreased risk of further injury.
Physical therapists frequently are unable to replicate eccentric training due to the lack of appropriate equipment and are therefore focusing on assisting manually during concentric exercise to increase eccentric emphasis.
Eccentric exercise has also been shown to reduce hamstring injury rates by 60-70% in various sports.
Injury to the ACL is a very common and significant knee injury, potentially resulting in limitations in range-of-motion, degenerative changes of the knee joint and muscular atrophy. 50% of all ACL injuries require surgery.
There is increasing evidence supporting eccentric exercise for the rehabilitation of anterior cruciate ligament (ACL) injuries. In particular, high-intensity eccentric exercises have long been shown as not only safe but highly effective for patients undergoing ACL reconstruction because it promotes greater changes in neural activation and muscle growth.
Effects of early progressive eccentric exercise on muscle structure after anterior cruciate ligament reconstruction.
Eccentric resistance training implemented three weeks after reconstruction of the anterior cruciate ligament can induce structural changes in the quadriceps and gluteus maximus that greatly exceed those achieved with a standard rehabilitation protocol. The success of this intervention can be attributed to the gradual and progressive exposure to negative work through eccentric exercise, ultimately leading to production of high muscle force. (http://www.jbjs.org/cgi/pmidlook- up?view=long&pmid=17332105)
An Eccentrically Biased Rehabilitation Program Early After TKA Surgery
An eccentrically-biased rehabilitation program early after total knee arthroplasty contributed to changes in physical function to norm-based levels. (http://www.hindawi.com/journals/ar- thritis/2011/353149/)
Effects of Early Progressive Eccentric Exercise on Muscle Structure After Following Anterior Cruciate Ligament Reconstruction
This study shows that eccentric resistance training used after an ACL reconstruction can achieve much greater structural changes to the joint and surrounding muscles in comparison to standard rehabilitation. (http://www.jbjs.org/cgi/pmidlook- up?view=long&pmid=17332105)
The Use of Eccentrically Biased Resistance Exercise to Mitigate Muscle Impairments Following Anterior Cruciate Ligament Reconstruction: A Short Review
A 12-week eccentric resistance training program 3 weeks after ACL reconstruction safely and dramatically improves quadriceps and gluteus maximus volume strength, and hopping ability in comparison to traditional rehabilitation. (http://www.ncbi.nlm.nih.gov/pmc/articles/P- MC3445117/)