The Acute Effect of Isometric Versus Isotonic Resistance Exercise in Patients With Patellar Tendinopathy

Participants will complete dynamic leg extension in a leg extension machine with a range of motion from approximately 90 degrees flexion to full extension. Each repetition will be completed with a 3s concentric contraction, 0s isometric and 4s eccentric contraction.This will be repeated for 8 repetitions and for 5 sets with 2 minutes rest between each set, as per Rio and colleagues. The load used during the isotonic exercise will be equivalent to participants 8 repetition maximum, which will be determined by an experienced tester in a standardised manner according to NSCA guidelines.

Participants will complete isometric quadriceps exercise, where they must hold a load statically for 45s with their knee in 60° flexion. This will be repeated for 5 sets with 2 minutes rest between each set. A load of 70% of the maximal voluntary isometric contraction (MVIC) will be used. MVIC will be assessed in an isokinetic dynamometer as per Rio and colleagues. Participants will be seated in a stable position in the dynamometer with the knee at 60° of knee flexion. First they will be familiarised with the procedure. Standardised instructions will be issued for participants to perform a maximal effort knee extension against the dynamometer for 3seconds. After a short break, the test will be repeated three times and the MVIC will be peak torque recorded during these three efforts.