Landing biomechanics, but not physical activity, differ in young male athletes with and without patellar tendinopathy

Key points

1. 01Symptomatic athletes showed significantly lower patellar tendon force loading impulse during landing than both the asymptomatic tendinopathy and healthy control groups (large effects, d = 0.91-1.40)
2. 02No differences in physical activity (steps per day, MVPA minutes per day) were found between any of the three groups
3. 03Asymptomatic athletes with tendon abnormalities did not show greater biomechanical or physical activity load than controls, contrary to expectations
4. 04Patient-reported function (VISA-P score) was not correlated with objective physical activity measures
5. 05Reduced tendon loading during landing may reflect a load-avoidance pattern that, if chronic, could reduce tissue capacity over time

How it was conducted

Design

Cross-sectional cohort study

Participants

41 male athletes aged 15-28 years, post-pubertal, all participating in organised sport

Groups

Symptomatic patellar tendon abnormality (SYM, n=13), asymptomatic patellar tendon abnormality (ASYM, n=14), healthy controls (CON, n=14)

Biomechanical assessment

3D motion capture and force plates during a box jump-landing task; patellar tendon force estimated via inverse dynamics

Physical activity monitoring

ActiGraph GT9X Link accelerometer worn for 7 days at the anterior-superior iliac spine; outcomes: steps/day, MVPA minutes/day, steps in MVPA/day

Primary outcome

Patellar tendon force loading impulse (FPTI) and physical activity load (steps-in-MVPA/day, MVPA min/day)

What they found

• SYM group had significantly lesser patellar tendon force loading impulse (FPTI) than CON group (p < 0.01, d = 1.40) and ASYM group (p < 0.05, d = 0.91)
• Knee extension moment impulse (KEMI) and negative knee work (KW) were also lesser in SYM compared to both CON (p < 0.01) and ASYM (p < 0.05) groups
• Peak patellar tendon force (FPT) was lesser in SYM compared to CON only (p < 0.05)
• No statistically significant differences in any biomechanical load variable between CON and ASYM groups (p > 0.05)
• No significant differences between any group for primary physical activity variables (steps-in-MVPA/day or MVPA min/day; p > 0.025)
• No significant differences in total steps/day between groups (p > 0.05)
• VISA-P score was significantly lower in SYM compared to both ASYM and CON (p < 0.001); SYM mean VISA-P was 76.1 +/- 13.37 points
• VISA-P score was not correlated with any physical activity measure (p > 0.05)

Limitations

• Cross-sectional design cannot establish whether altered biomechanics preceded or resulted from tendinopathy
• Symptom chronicity was not recorded for the symptomatic group, which may have influenced movement patterns
• General accelerometry metrics (steps/day, MVPA) may not capture sport-specific jump-loading that is most relevant to patellar tendinopathy
• Seven-day monitoring period may not represent habitual load across a full training season, and daily pain was not tracked during the wear period

Why it matters

For patients

If you have patellar tendinopathy, you may already be unconsciously protecting the tendon during landing movements, but this pain-avoidance pattern could weaken the tendon over time if not addressed with guided loading.

For clinicians

Biomechanical landing assessment can detect under-loading of the patellar tendon in symptomatic athletes, information that is not captured by patient-reported outcomes or general activity monitors alone, and should inform progressive loading rehabilitation.

For readers

This study provides the first objective evidence that biomechanical loading differences, not general activity levels, distinguish symptomatic patellar tendinopathy in young male jumping athletes, highlighting the need for tissue-specific load monitoring.