Clinical outcomes, structure, and function improve with both heavy and moderate loads in the treatment of patellar tendinopathy: a randomized clinical trial

Key points

1. 01Heavy (90% 1RM) and moderate (55% 1RM) loading produced equivalent VISA-P improvements at 12 and 52 weeks
2. 02Patient satisfaction was identical at 95% in both groups at 12 weeks
3. 03Neither group fully returned to pre-injury function or normalized tendon structure by 1 year
4. 04Muscle strength increased significantly in both groups (HSR: ~15%, MSR: ~10%) without a difference between groups
5. 05Doppler vascularization decreased over time in both groups but the change was not statistically significant within each group at 12 weeks

How it was conducted

Design

Prospective, randomized, controlled, single-blinded, superiority trial (Level 1 evidence)

Participants

44 male recreational athletes aged 20-45 with chronic patellar tendinopathy (3-12 months duration), confirmed by ultrasound

Groups

HSR group (n=21): slow resistance training progressed to 90% of 1RM; MSR group (n=21): slow resistance training maintained at 55% of 1RM; total exercise volume matched

Intervention

12-week program, 3 sessions/week (bilateral leg press and unilateral knee extension), with follow-up at 52 weeks

Primary outcome

VISA-P score change from baseline to 12 weeks

Secondary outcomes

NRS pain scores, single-leg decline squat pain, muscle strength, jump height, ultrasound (tendon thickness, power Doppler area), MRI cross-sectional area

What they found

• VISA-P score (HSR): 58.8 +/- 4.3 at baseline, 70.5 +/- 4.4 at 12 weeks, 79.7 +/- 4.6 at 52 weeks; change 0-12 weeks: 11.7 +/- 2.8 (95% CI 4.1 to 19.3), p < 0.01
• VISA-P score (MSR): 59.9 +/- 2.5 at baseline, 72.5 +/- 2.9 at 12 weeks, 82.6 +/- 2.5 at 52 weeks; change 0-12 weeks: 12.6 +/- 2.8 (95% CI 5.0 to 20.2), p < 0.01
• No significant group effect (p = 0.57) or group x time interaction (p = 0.89) for VISA-P; significant time effect (p < 0.0001)
• Patient satisfaction at 12 weeks: 95% (18/19) HSR and 95% (20/21) MSR (p > 0.99); at 52 weeks: 84% HSR and 95% MSR (p = 0.33)
• NRS pain during running, squats, and preferred sport: significant reduction with time (p < 0.0001) with no group or group x time effect
• Single-leg decline squat NRS decreased from 4.3 to 2.0 (HSR) and 3.9 to 1.9 (MSR) at 12 weeks (p < 0.0001); no group x time (p = 0.93) or group effect (p = 0.73)
• Muscle strength increased significantly with time (p < 0.0001) with no group effect (p = 0.75) or group x time interaction (p = 0.25)
• Power Doppler area decreased overall (time p = 0.01) but without group (p = 0.30) or group x time effect (p = 0.22); relative change 0-52 weeks: -41% (HSR) and -36% (MSR)
• Tendon AP thickness: no significant time (p = 0.10), group (p = 0.37), or group x time (p = 0.58) effect
• MRI cross-sectional area (proximal, middle, distal): no significant group effect or change from baseline to 12 weeks in either group
• Jump height (CMJ and SJ): no significant group, time, or group x time effect on height; pain during jumps decreased significantly (p = 0.01)

Limitations

• No non-exercise control group was included, so spontaneous improvement over time cannot be ruled out
• The 2-week washout period from prior treatment was relatively short
• Repetitions and total time under tension differed between groups because only volume was matched, and these parameters may independently influence outcomes
• All participants were male recreational athletes, limiting generalizability to women, elite athletes, or other populations

Why it matters

For patients

Both heavy and moderate resistance training programs produce similar improvements in knee pain and function, so patients can choose the approach that best suits their preferences and ability to comply.

For clinicians

Load magnitude alone (55% vs 90% of 1RM) does not determine the outcome when total exercise volume is matched, suggesting flexibility in prescription; neither regimen fully restored function or normalized tendon structure at 1 year, indicating recovery timelines extend well beyond the acute treatment phase.

For readers

This well-designed RCT challenges the assumption that higher loads are necessary for tendon rehabilitation, showing that moderate loads can be equally effective when volume is controlled.