Controlled Research Study on Isometric(s) & Tendon Pain In-Season
Summary
The 2016 study by Martine van Ark, Jill Cook, and colleagues, published in the *Journal of Science and Medicine in Sport*, investigated whether isometric or isotonic exercises could reduce pain and improve function in jumping athletes with patellar tendinopathy without requiring them to reduce training or competition during the season. This randomized controlled trial included 29 volleyball and basketball players with an average of three years of tendon pain, of whom 20 completed the four-week program. Participants were divided into two groups: one performing isometric knee extension or leg press exercises (5 sets of 45-second holds at 80% of maximum voluntary contraction) and the other performing isotonic exercises (4 sets of 8 repetitions at 80% of 8-repetition maximum with a 3-second eccentric phase), both four times per week.
Both interventions led to significant and clinically meaningful reductions in pain, with the isometric group reporting a median decrease of 2.5 points on the Numeric Rating Scale (NRS) and the isotonic group a 3.0-point drop—both exceeding the minimum clinically important difference of 2 points. Function, measured by the Victorian Institute of Sport Assessment-Patella (VISA-P) score, improved by approximately 8.5 points in the isometric group and 9.5 points in the isotonic group, approaching but not fully reaching the 13-point threshold for clinical significance. Importantly, there were no significant differences between the two exercise types, and no changes to sport-specific training were required.
This was the first randomized trial to demonstrate that structured tendon loading—whether isometric or isotonic—can effectively manage patellar tendinopathy symptoms in-season. Co-authored by tendinopathy expert Jill Cook, the study reinforces the role of isometrics in immediate pain relief (consistent with prior work) while showing that isotonic loading is equally effective over a short-term program. The key clinical message is clear: athletes with tendon pain do not need to stop playing—consistent, progressive loading of the tendon, using either approach, can reduce pain and support function during competition.
Concern(s)
The 4-week trial shows meaningful short-term pain relief and functional gains, but lacks long-term follow-up and structural imaging—leaving uncertainty about sustained benefits, tendon adaptation, or risk of symptom recurrence once sport loads resume fully.
Application
For athletes with in-season patellar tendinopathy, insert 3–4 weekly sessions of isometric knee extension (5×45s @ 80% MVC) or isotonic leg press (4×8 @ 80% 8RM, 3s eccentric) after practice—no volume reduction needed. This rapidly lowers pain (within 1–2 weeks), preserves VISA-P function, and supports continued jumping load, making it ideal for maintaining performance while managing tendon symptoms.
