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Issue 15

Table of Contents

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Exercise for Patella Tendinopathy – More than just eccentrics

Effectiveness of progressive tendon-loading exercise therapy in patients with patellar tendinopathy: a randomized clinical trial

Dr. Cody Misuraca PT, DPT

Key takeaways:
  • Eccentric exercise is a simple and viable option for managing symptoms with patella tendinopathy
  • Isometrics, isotonics, and dynamic exercise may offer slightly better outcomes if dosed appropriately
  • Exercise for patella tendinopathy should be performing for a minimum of 6 months for significant improvements in symptoms
  • Roughly half of athletes can expect to return to sport by 6 months regardless of the exercise routine, but most will not be back to their prior level
  • Setting realistic expectations for time to improve symptoms and return to sport is key


Treating painful tendons in an athletic population can be a challenging task, and is an area that holds special interest for me as a rehab professional. Like many rehab professionals, I have my own pain and injury history which has informed my interests and drives in professional practice. When I was in PT school, I spent a lot of time training the weightlifting movements, snatch and clean and jerk – I never had a coach for that, and based my training largely off of free programs and templates. At that point in my training history, I had not yet become familiarized with the concept of Rating of Perceived Exertion, or RPE, in the context of resistance training.

As a result, a lot of my training was close to, or all the way up to failure. At some point along the way I developed a nasty case of bilateral quadriceps tendinopathy – most days I could barely flex my knees past 90 degrees getting out of bed in the morning due to pain and stiffness, and my training became quite limited by my symptoms.

In PT school I had learned about eccentric exercise for tendinopathy, but was struggling to implement it alongside my other lifting – and to be honest, at the time I wasn’t very good at pulling myself back in my own training either. Thankfully, I was connected with a handful of experienced rehab clinicians who introduced me to the concept of Heavy Slow Resistance (HSR) training ala Kongsgaard et al¹.

For those who aren’t familiar, these researchers conducted an RCT comparing corticosteroid injection, slow eccentric single limb squats on a decline board, and HSR utilizing a 3-0-3 movement tempo (3” down, no pause, and 3” back up) in the treatment of patellar tendinopathy. In summary, this study found that the classic eccentric exercise and HSR resulted in similar symptomatic improvements after 12 weeks of training that persisted until the 6 month follow-up, with higher patient satisfaction in the HSR group compared to the eccentric exercise group.

In this study the HSR group utilized a back squat, leg press, and machine hack squat – I adapted their protocol to a couple variations of barbell squats and found a gym with a knee extension machine. After 12 weeks, my symptoms had almost fully resolved, and I was able to return to heavy squatting without pain.

I quickly started using a similar protocol with my patients with knee tendinopathies, and have continued using similar concepts in clinical practice 7 years down the line. As a rehab professional, I’ve found HSR to be a useful approach when working with people who lift weights regularly, as the tempo constraint can be easily applied to movements that they are already performing in the gym.

However, some athletic populations don’t have the access, time, or interest in gym-based exercise, or have a hard time being consistent with slow-tempo exercises. A simple one-exercise program of eccentric single leg squats on a slant board might be more feasible in these cases, but these are not the only options for using exercise to manage tendinopathy.

A study published in 2021 by Breda et al² provides us with additional data comparing eccentric exercise to an alternative exercise intervention including isometric and dynamic exercise, and is the topic of this month’s research review. Be prepared, this study used a somewhat complex exercise protocol, but I have done my best to lay it out in a simple, understandable fashion.

The researchers started by recruiting athletes participating in sport at least 3 times per week who were experiencing pain about the patella tendon, and randomized 38 participants each into either an Eccentric Exercise Therapy (EET) group, or a Progressive Tendon-Loading Exercise (PTLE) group. The final follow-up was performed at 24 weeks after initiation of exercise. The eccentric exercise group performed single leg eccentric squats on a decline slant board, aiming to elicit pain of ≥5/10, and were advised to add load in a backpack if needed to elicit pain.

This was performed twice daily for a minimum of 3 weeks and up to 24 weeks, until pain with additional load was ≤3/10 – at this point they continued with the eccentric decline squat 2x/week and initiated sport-specific exercises that were based on their primary sport, which could include jumping, cutting, shooting, passing, etc every 2-3 days.

If these exercises did not provoke pain, then the participants initiated 30-minute sessions of low-intensity group training for their sport, and could return to sport competition once they could perform 3 group sessions with ≤3/10 pain 24 hours afterwards. While the EET group performed two primary stages prior to initiation of return to sport activities (eccentric exercises only, and then sport-specific exercises), the PTLE group performed 4 stages of exercise: Isometrics, Isotonics,

Energy-Storage, and Sport-Specific exercise. During the Isometric phase, they performed daily isometrics using either a knee extension or leg press machine, holding at 60 degrees of knee flexion. If the participants didn’t have a leg extension or leg press machine available, they substituted a single leg wall squat with the knee at 90 degrees, with the maximum load they could hold for 45” at a time.


During the Isotonic phase, they added a dynamic single leg press or knee extension exercise, starting with sets of 15 repetitions and progressing to sets of 6 based on tolerance, with a maximum knee flexion angle of 60 degrees, progressing to 90 degrees over time. They performed these exercises every second day, and continued with the Isometric phase exercises on the other days. Additionally, if a leg press or knee extension machine was not available, they were permitted to substitute with a walking lunge or box step up.



During the Energy-Storage phase, they added jump squats, jump split squats, box jumps, straight line running, and zig-zag running. They progressed exercise intensity in this phase by transitioning from double leg landings to single leg landings for the jumping exercises, increasing the number of sets of jumping exercises, and by increasing speed for the running exercises.



The Energy-Storage exercises were performed every third day, with the Isotonic exercises continued on each second day, and the Isometric exercises on each first day. Finally, they transitioned to Sport-Specific exercises that were based on their primary sport, which could include jumping, cutting, shooting, passing, etc. These were performed every 2-3 days with Isometric exercises performed on the other days.

If these exercises did not provoke pain, then the participants initiated 30-minute sessions of low-intensity group training for their sport, and could return to sport competition once they could perform 3 group sessions with ≤3/10 pain 24 hours afterwards. Participants were allowed to progress from one phase to the next when they could perform at least a week of the current phase’s exercises with ≤3/10 pain, and could perform a single leg eccentric squat with ≤3/10 pain. A more thorough explanation of both groups’ exercise protocols is also available in the study appendix.

The final analysis found that both groups improved in terms of self-reported knee symptoms and function via the VISA-P questionnaire, with greater improvement at 24 weeks in the PTLE group. However, there was no significant difference found between groups for rate of return to sport (43% PTLE vs 27% ECC with p=0.13), satisfaction, or exercise adherence.


I think that the design used for the PTLE group was pragmatic in that it allowed faster progression for participants who could tolerate it, and slower progression for those who could not, ultimately doing a good job of matching exercise intensity to their personal capacities.

Both groups saw a fair amount of improvement in knee symptoms and function, so a much simpler exercise program such as the one used in the ECC group in this study may be preferable for some athletes with patella tendinopathy, though a more comprehensive program may offer better outcomes. The main takeaway that I have from this study is that, similar to what was found by Kongsgaard et al, there is more than one path available when it comes to exercise for improving symptoms of patella tendinopathy.

Kongsgaard et al also administered the VISA-P questionnaire to assess self-reported knee symptoms and function; they found that the eccentric exercise group in their study improved by about 23 points on the VISA-P which is roughly the same as the 19-point improvement in VISA-P average for the EET group from the current study by Breda et al.

And while Kongsgaard et al’s HSR group differed in terms of exercise selection and progression from Breda et al’s PTLE group, they found a 30-point improvement of VISA-P average for HSR vs a 29-point improvement for PTLE in the current study. One final consideration to make based on the study by Breda et al is to be realistic with expectations for time to return to sport. While a large majority of both the EET and PTLE group had returned to their desired sport in some capacity at the 24-week mark, less than 50% of participants in each group returned at their prior level.


This lines up with my own experience as a clinician working with people who are athletic and have patella tendinopathy – a ton of headway can be made in the first 6 months or so but I prefer to counsel people that this can be a much longer-term process, often up to a year or more. This can sound discouraging initially but setting that expectation early and often can be helpful to refer back to when progress is slow.

Additionally, focusing time on establishing patient comfort and independence with the exercise routine, and checking for understanding regarding how to adjust exercise intensity to account for fluctuation in symptoms over time can go a long way to encourage longer-term adherence to a routine.




Cody Misuraca is a physical therapist and strength coach in Seattle, WA. He works as a sports physical therapist for a community hospital system and also owns Waypoint Strength and Performance LLC, which offers strength coaching services. The views and opinions expressed in this review are those of the writer and do not necessarily reflect the views or positions of any institutions he is associated with.