Overview and etiology:
The term “tendinitis” or any [insert any body part] with “itis” is tossed around as if it is the only possible cause for musculoskeletal pain. However, the “itis” is not really true. A tendon, specifically the Achilles tendon, is not really inflamed, rather it is deranged (tendiopathic / tendinopathy). In January 2013 the Annals of Human Genetics published an article that demonstrated Achilles Tendinopathy is associated with gene polymorphism (Abrahams, et al., 2013). COL51A is a gene that encodes the development and organization of Type V collagen. This collagen can be found in ligaments, tendons, and connective tissue. COL51A plays an integral role in development and maintenance of connective tissue. Abrahams, et al. (2013) demonstrated that polymorphisms occur in the COL51A gene causing altered structure of collagen resulting in tendinopathy.
The tendon may become fusiform or thickened, but it is due to cellular derangement rather than inflammation. Kannus and Jozsa in a controlled study of 891 patients with Achilles tendon rupture found that 97% of patients had degenerative changes in the ruptured tendon. The study also found that 34% of asymptomatic tendons also had degenerative changes (2)
In tendinopathic tissue the collagen formation becomes deranged through sedentary lifestyle, excessive activity, and poor neuromuscular alignment and coupling. Couppe´, Kongsgaard, et. al, looked at effects of habitual loading in elite badminton and fencers athletes and found that the tendon will undergo hypertrophy and increased stiffness with excessive loading (3). Another study found that immobilization led to decreased mechanical properties of the tendon, while exercise increased mechanical properties (4). If there is movement impairment centralized within the foot and ankle region, such as rearfoot eversion or tibial external rotation it can lead to various symptomatic responses, including plantar fasciitis, medial tibial stress syndrome and Achilles tendinopathy (5).
Appropriate loading and exercise:
Excessive loading and sedentary lifestyle may lead to tendinopathy of the Achilles tendon, so there is a sweet spot – not too much and not too little. A systematic review in 2012 found that removing athletes from competition is not beneficial for treatment of tendinopathy (6).
Eccentric exercise has been recommended in the treatment of tendinopathy for more than 30 years. Evidence supporting the use of eccentric exercise in treatment of tendinopathy is well-documented and strong. A systematic review published in 2012 found eccentric loading to be beneficial for treatment of Achilles tendinopathy (7). Murtaugh and Ihm demonstrated that eccentric exercises can be effective in the treatment of tendinopathies at various locations of the body (8). The authors also found that performing sets of 15 repetitions of each exercise 1-2 times daily has the greatest benefit.
Clark and Lucett demonstrated that corrective lower extremity muscular imbalance training and enhancing neuromuscular coupling can reduce lower extremity injury (9). Inhibiting overactivity of the peroneals, lateral gastrocnemius and biceps femoris, while simultaneously reversing hypotonicity of the medial gastrocnemius, anterior / posterior tibialis, and medial hamstrings can correct foot and ankle malalignment. Correcting these dysfunctional movement patterns can improve Achilles tendinopathy.
Why does exercise work? Physiology of Loading:
Therapeutic exercise has traditionally been used to restore range of motion, increase strength and enhance functional movement. However, it is becoming more apparent that exercise stimulates tissue regeneration. Following the principles of mechanotransduction, the passage of forces generated through movement from cells to cell nuclei plays an important role in tissue repair. Clinical research is advancing understanding of how to best load tendon to facilitate repair. However, the differentiation of stem or progenitor cells and increases in fibroblast is needed to maintain homeostasis and for repair of tendons, cartilage, bone and ligaments. Appropriate load can stimulate progenitor cells and regeneration collagen tissue in the Achilles tendon as well as other tendons.
The issue of tendon and tendinopathy provides unique perspective to this discussion of therapeutic exercise and mechanobiology. The original rehabilitation protocols developed when tendinopathy was viewed as tendinitis – long before mechanobiology emerged – are no longer relevant. Obviously there is not a one-size-fits-all protocol. Clinical judgment and observation lead to the development of exercise programs that induce a mechanical signal at the cellular level. Patient response will determine how much is too much and how little is too little. Clinical research demonstrated, however, that eccentric exercise programs can be quite effective.
Our traditional views of therapeutic exercise and the treatment of Achilles Tendinopathy must be reconsidered. Exercise is a modality of repair and well as a means of restoring function. Exercise that does not exacerbate pain and other symptoms of inflammation may lead to more rapid tissue repair which can lead to earlier recovery. The deleterious effects of rest and immobilization on tissue health must be balanced against benefits of pain relief and comfort. However, when these guidelines are observed, loading through exercise likely provides the stimulus for repair and recovery in the most efficient manner possible. Tissue loading facilitates repair much better than ice and other bioelectrical modalities.
- Abrahams Y, Laguette MJ, Prince S, and Collins M. Polymorphisms within the COL5A1 3′-UTR That Alters mRNA Structure and the MIR608 Gene are Associated with Achilles Tendinopathy. Ann Hum Genet. (Epub – ahead of print) Jan 2013.
- P Kannus and L Jozsa. Histopathological changes preceding spontaneous rupture of a tendon. A controlled study of 891 patients. J Bone Joint Surg Am. 1991 Dec 01;73(10):1507 1507-1525.
- C. Couppe´, M. Kongsgaard, P. Aagaard, P. Hansen, J. Bojsen-Moller, M. Kjaer, and S. P. Magnusson. Habitual loading results in tendon hypertrophy and increased stiffness of the human patellar tendon. J Appl Physiol. 105: 805–810, 2008.
- Adamantios Arampatzis, Kiros Karamanidis, and Kirsten Albracht. Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude. J of Exper. Biology. 2007. 2743-2753.
- Sahrmann SA. Diagnosis and Treatment of Movement Impairment Syndromes. St. Louis, MO: Mosby; 2002.
- Saithna A, Gogna R, Baraza N, Modi C, Spencer S. Eccentric Exercise Protocols for Patella Tendinopathy: Should we Really be Withdrawing Athletes from Sport? A Systematic Review. Open Orthop J. 2012;6:553-7
- Sussmilch-Leitch et al. Physical therapies for Achilles tendinopathy: systematic review and meta-analysis. Journal of Foot and Ankle Research. 2012, 5:15.
- Murtaugh and Ihm. Eccentric Training for the Treatment of Tendinopathies. American College of Sports Medicine –Training, Prevention and Rehabilitation. Volume 12 & Number 3 & May/June 2013.
- Clark, MA, and Lucett, SC. NASM’s Essentials of Corrective Exercise Training. 2010. Philadepha.