The function of the lower limb tendons is to transmit very large forces exerted by the ground and the attaching muscle or muscle groups to the skeleton. This is an integral component for human locomotion and athletes ability to sprint, change direction and jump. [1,2]. Tendons are made up of collagen fibrils that allow the storage and release of strain energy during locomotion [3,4] and behave very much like a power amplifier by transmitting force from muscular contractions.
Tendinopathy is common in athletes exposed to repeated high tendon loading  with a reported point prevalence of up to 36% for Achilles tendinopathy in running athletes and up to 45% for patella tendinopathy in volleyball players [6,7]. Tendinopathy is characterized by matrix disintegration as a consequence of; unaccustomed high tendon loads, changes in surface or repeated overstraining from high tendon loads, plantaris compression, ageing, degeneration, para-tendinopathy and/or partial ruptures, as well as systemic factors such as high cholesterol or diabetes . Antibiotic medication (fluoroquinolone) is also responsible for onset of tendinopathic symptoms and or rupture.
Economical runners show a higher contractile strength and higher tendon stiffness in the triceps surae . Conversely, tendinopathy is correlated with a reduction in rate of force development in the soleus muscle . Poor tendon stiffness, or the ability to maintain a strong non-yielding tendon, directly impacts the maximum rate of force development . Often athletes will experience morning pain and stiffness with some accompanying warm-up stiffness, which may reduce after a period of time but often leads to a reduction in speed, agility or jump height as a result. Early diagnostics and prevention is the key to minimizing the occurrence and frequency of tendinopathy. A previous study observed one third of asymptomatic players had MRI imaging indicative of patellar tendinopathy two months prior to the start of the season . A very recent systematic review using ultrasound imaging of asymptomatic tendons found that hypo-echoic regions increase the risk of developing symptoms in patellar tendinopathy by 4.2 times and 7.2 times in the Achilles tendon . Although the risk of complete rupture for athletes who do experience tendinopathy is quite low, research in the NBA has found that returning from rupture has the greatest deleterious effect on performance than any other injury in terms of performance and longevity of playing career  .
Prevention is the key to reduce the prevalence of Achilles and patella tendinopathy in elite sporting populations. Injury surveillance research   suggests that maintaining consistent playing loads in and out of season, conditions athletes’ tendons for high tensile load requirements. Heavy prophylactic pre and in-season loading has the benefit of conditioning tendons to high tensile load requirements by changing the mechanical properties of the tendon, mainly stiffness qualities, strain rates and elastic modulus  . Novel imaging modalities like Ultrasound Tissue Characterization (UTC) has been shown to be a sensitive objective method for monitoring intra-tendinous responses to game loads  to prevent the early onset of tendon degradation and subsequent symptoms but also useful in determining the cause of tendinopathy . Differential diagnosis is key in the application of interventions and loading-based strategies, as a “one size fits all” approach is a pathway for ineffective athlete or patient care.
Conservative management of tendinopathy has included many types of therapy from the use of non-steroidal anti-inflammatories in the acute/reactive stages, to massage, stretching, eccentric exercises and shockwave but by far and above the most effective methods has been demonstrated in a recent systematic review . Contraction type was found to be less important, rather a high magnitude of load is the critical determinant in improving athletes’ symptoms.
So what does this mean for your training?
Conditioning your body with progressive strength training whilst gradually increasing your elastic load tolerance (running, jumping and cutting) without doubling your activity, at any level of sport is crucial in preventing injuries. If you begin to experience Achilles or patella tendon soreness, a reduction in your training or playing time (relative rest) with the use of short term NSAID’s, such as over the counter ibuprofen or aspirin. Gradual re-introduction of elastic loading, whilst monitoring your morning pain and stiffness to ensure you don’t begin experiencing increasing tendon pain.
Jarrod is the Co-Founder of Total Performancend a Sports Physiotherapist, consulting to NBA teams in the US, and to English Premiere League teams and Premiership Rugby in the UK.
Jarrod has a Masters in Sports Physiotherapy from La Trobe University, Melbourne Australia as well as a BAppSc in Physiotherapy from University of Sydney and a BHSc from the University of Technology, Sydney.
Jarrod specialises in elite sports, having worked in track and field in the US and the UK, more recently as a consultant for British Athletics. He shares his time between Total Performancehere he assists NBA teams in the management and prevention of tendon injuries, whilst also providing onsite full biomechanics and strength diagnostics with the use of computing learning technology (AI). He also consults at the Fortius Clinic (UK) where he is participating in research looking at novel intervention strategies for Achilles tendinopathy.
 Magnusson SP, Narici MV, Maganaris CN, Kjaer M. Human tendon behaviour and adaptation, in vivo. Journal of Physiology. 2008;586:71–81. 3.
 McNeill AR. Tendon elasticity and muscle function. Comparative biochemistry and physiology. Part A, Molecular & integrative physiology. 2002;133:1001–11.
 Alexander R. Energy-saving mechanisms in walking and running. Journal of Experimental Biology. 1991;160:55–69. 5.
 Fukunaga T, Kubo K, Kawakami Y, Fukashiro S, Kanehisa H, Maganaris CN. In vivo behaviour of human muscle tendon during walking. Proceedings of the Royal Society of London. Series B, Biological Sciences.. 2001;268:229–33.
 Maffulli N, Wong J, Almekinders LC. Types and epidemiology of tendinopathy. Clinical Sports Medicine 2003: 22: 675–692.
 Lian OB, Engebretsen L, Bahr R. Prevalence of jumper’s knee among elite athletes from different sports: a cross-sectional study. American Journal of Sports Medicine 2005
 Hirschmuller A, Frey V, Deibert P, Konstantinidis L, Mayer F, Sudkamp N. Achilles tendon power Doppler sonography in 953 long distance runners – a cross sectional study. Ultraschall Med 2010: 31: 387–393.
 Ranger TA, Wong AMY, Cook, JL, Gaida JE. Is there an Association Between Tendinopathy and Diabetes Mellitus? A Systematic Review with Meta-Analysis. British Journal of Sports Medicine doi:10.1136/bjsports-2015-096288
 Arampatzis, A., Karamanidis, K., & Albracht, K. (2007). Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude. The Journal of Experimental Biology, 210(Pt 15), 2743–2753. doi:10.1242/jeb.003814
 Wang, H. K., Lin, K. H., Su, S. C., Shih, T. T. F., & Huang, Y. C. (2012). Effects of tendon viscoelasticity in Achilles tendinosis on explosive performance and clinical severity in athletes. Scandinavian Journal of Medicine and Science in Sports, 22(6), e147–55. doi:10.1111/j.1600-0838.2012.01511.
 Hansen, P., Bojsen-Moller, J., Aagaard, P., Kjaer, M., & Magnusson, S. P. (2006). Mechanical properties of the human patellar tendon, in vivo. Clinical Biomechanics, 21(1), 54–58. http://doi.org/10.1016/j.clinbiomech.2005.07.008
 Walczak BE, McCulloch PC, Kang RW, Zelazny A, Tedeschi F, C. B. (2008). Abnormal findings on knee magnetic resonance imaging in asymptomatic NBA players. Journal of Knee Surgery, 21(1), 27–33.
 Drew, B. T., Smith, T. O., Littlewood, C., & Sturrock, B. (2012). Do structural changes (eg, collagen/matrix) explain the response to therapeutic exercises in tendinopathy: a systematic review. British Journal of Sports Medicine, 1–8. http://doi.org/10.1136/bjsports-2012-091285
 Minhas, S. V., Kester, B. S., Larkin, K. E., & Hsu, W. K. (2016). The Effect of an Orthopaedic Surgical Procedure in the National Basketball Association. The American Journal of Sports Medicine. http://doi.org/10.1177/0363546515623028
 Amin, N. H., Old, A. B., Tabb, L. P., Garg, R., Toossi, N., & Cerynik, D. L. (2013). Performance outcomes after repair of complete achilles tendon ruptures in national basketball association players. The American Journal of Sports Medicine, 41(8), 1864–8. http://doi.org/10.1177/0363546513490659
 Hulin, B. T., Gabbett, T. J., Caputi, P., Lawson, D. W., & Sampson, J. A. (2016). Low chronic workload and the acute:chronic workload ratio are more predictive of injury than between-match recovery time: a two-season prospective cohort study in elite rugby league players. British Journal of Sports Medicine, bjsports-2015-095364. http://doi.org/10.1136/bjsports-2015-095364
 Gabbett, T. J., Hulin, B. T., Blanch, P., & Whiteley, R. (2016). High training workloads alone do not cause sports injuries: how you get there is the real issue. British Journal of Sports Medicine, 50(8), bjsports-2015-095567. http://doi.org/10.1136/bjsports-2015-095567
 Arampatzis, A., Karamanidis, K., & Albracht, K. (2007). Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitude. The Journal of Experimental Biology, 210(Pt 15), 2743–2753. http://doi.org/10.1242/jeb.003814
 Arampatzis, A., Peper, A., Bierbaum, S., & Albracht, K. (2010). Plasticity of human Achilles tendon mechanical and morphological properties in response to cyclic strain. Journal of Biomechanics, 43(16), 3073–3079. http://doi.org/10.1016/j.jbiomech.2010.08.014
 Rosengarten, S. D., Cook, J. L., Bryant, A. L., Cordy, J. T., Daffy, J., & Docking, S. I. (2014). Australian football players’ Achilles tendons respond to game loads within 2 days: an ultrasound tissue characterisation (UTC) study. British Journal of Sports Medicine. http://doi.org/10.1136/bjsports-2013-092713
 Masci, L., Spang, C., Schie, H. T. M. Van, & Alfredson, H. (2015). Achilles tendinopathy — do plantaris tendon removal and Achilles tendon scraping improve tendon structure ? A prospective study using ultrasound tissue characterisation, 1–6. http://doi.org/10.1136/bmjsem-2015-000005
 Bohm, S., Mersmann, F., & Arampatzis, A. (2015). Human tendon adaptation in response to mechanical loading: a systematic review and meta-analysis of exercise intervention studies on healthy adults. Sports Medicine - Open, 1(1). http://doi.org/10.1186/s40798-015-0009-9
Tim DiFrancesco, PT, DPT, ATC, CSCS served 6 seasons as the Head Strength & Conditioning Coach of the Los Angeles Lakers and is the founder of TD Athletes Edge. He is nationally renowned for his evidence-based and scientific approach to fitness, training, nutrition, and recovery for athletes and fitness enthusiasts.
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Tim DiFrancesco, PT, DPT spent 6 seasons as the Head Strength & Conditioning Coach of the Los Angeles Lakers and is the founder of TD Athletes Edge. He is nationally renowned for his evidence-based and scientific approach to fitness, training, nutrition, and recovery for athletes and fitness enthusiasts.