Kneecap pain: leg extensions hurt most in the middle of the range
In short
In 100 people with patellofemoral pain (pain at the front of the knee), 94% felt pain in at least one range of a resisted knee extension. The 70°–25° mid-range scored on average 1 point higher on a 0–10 pain scale than the 90°–45° range, and the near-lockout 45°–0° range produced 27.5 to 29.9 less torque than the other two. Instead of dropping quad work, people with kneecap pain can shift to the range that hurts less.
Quad strengthening is the standard prescription for patellofemoral pain, but evidence on which part of a leg extension to train has been mixed. A team at the Federal University of Ceará in Brazil tested 100 patients across three ranges and found that the most painful range and the weakest range were not the same.
How was it measured?
- Participants: 100 people with a clinical diagnosis of patellofemoral pain, tested July to November 2024.
- Method: knee extension strength on an isokinetic dynamometer in three ranges: 90°–45° (deeply bent), 70°–25° (mid-range) and 45°–0° (near lockout), where 0° is fully straight.
- Outcomes: a 0–10 pain rating and torque for each range.
Which range hurt most?
94% of participants reported pain in at least one range. The 70°–25° mid-range scored 1 point higher on average (95% CI 0.4 to 1.6) than the deeply bent 90°–45° range. Pain did not differ between the near-lockout and deeply bent ranges.
So should you just train near lockout?
That range was the weakest. Torque in the 45°–0° range was 27.5 lower than the mid-range and 29.9 lower than the deeply bent range. The authors suggest choosing the range by symptoms, balancing pain against how much force you can produce. In this data set, 90°–45° combined lower pain with higher torque.
What does this mean for your squat?
The study only looked at seated knee extensions, so it does not transfer directly to squats. Use it as a reason to keep training the quads through a less painful range on accessories rather than shutting down leg day. Squat 1RMs logged in fairlift should still meet full depth, so do not record a depth-limited set as a max. More ways to take load off the knees are in knee-friendly leg training.
This was a one-time cross-sectional measurement. It did not test whether training in a specific range reduces pain over time. Persistent knee pain deserves a professional assessment before you settle on a range.
Frequently asked questions
Can I do leg extensions with patellofemoral pain?
Quad strengthening is the standard treatment for patellofemoral pain. In a study of 100 patients, the 70°–25° range hurt most, so adjusting to a less painful range is an option.
Which part of a leg extension hurts most?
In 100 people with patellofemoral pain, the 70°–25° mid-range scored on average 1 point higher on a 0–10 pain scale than the 90°–45° range.
Why not only train the last part near lockout?
The 45°–0° range was not more painful, but torque there was 27.5 to 29.9 lower than in the other two ranges, which limits how hard the quads can work.
Does a squat with reduced depth count as a 1RM?
No. Squat 1RMs used for the Muscle Index are only comparable when they meet the same depth standard.
Source: PubMed