Static and Dynamic Quadriceps Stretching Exercises in Patients With Patellofemoral Pain: A Randomized Controlled Trial

Abstract

Background: Limited data are available on the effect of stretching exercise in patients with patellofemoral pain (PFP) who have inflexible quadriceps, which is one of the various causes of PFP syndrome. This study compares quadriceps flexibility, strength, muscle activation time, and patient-reported outcomes after static and dynamic quadriceps stretching exercises in patients with PFP who had inflexible quadriceps.

Hypothesis: Quadriceps flexibility and strength, muscle activation time, and patient-reported outcomes would improve with dynamic quadriceps stretching as compared with static quadriceps stretching exercises.

Study design: Randomized controlled trial.

Level of evidence: Level 2.

Methods: Of the 44 patients included in the study, 20 performed static stretching and 24 performed dynamic stretching. Quadriceps flexibility was assessed by measuring the knee flexion angle during knee flexion in the prone position (the Ely test). Muscle strength and muscle activation time were measured using an isokinetic device. The patient-reported outcomes were evaluated using the visual analogue scale for pain and anterior knee pain scale.

Results: No significant differences in quadriceps flexibility and strength, muscle activation time, and patient-reported outcomes in the involved knees were found between the 2 groups (P values > 0.05).

Conclusion: Quadriceps flexibility and strength, muscle activation time, and patient-reported outcomes in patients with PFP who had inflexible quadriceps showed no significant differences between the static and dynamic quadriceps stretching exercise groups.

Clinical relevance: Both static and dynamic stretching exercises may be effective for improving pain and function in patients with PFP who have inflexible quadriceps.

Keywords: dynamic stretching; muscle activation time; muscle strength; quadriceps flexibility; static stretching.

Figure 1.

Study flow diagram.

Figure 2.

Quadriceps flexibility (degrees), strength (N·m·kg⁻ × 100), muscle activation time (ms), and patient-reported outcomes (points) of the involved knees before and after quadriceps stretching in the static (A) and dynamic (B) stretching groups. AKPS, anterior knee pain scale; VAS, visual analog pain scale.