Patellofemoral joint forces during ergometric cycling
6 healthy men: peak patellofemoral compressive force was 905 N (1.3 times body weight) at 120 W, 60 rpm, middle saddle height and an anterior foot position; the forces rose with workload and with a lower saddle, while pedalling rate and foot position did not change them significantly; a model-based estimate, no injury or pain data
The study estimated patellofemoral joint forces generated during pedalling on a bicycle ergometer under different workloads, pedalling rates, saddle heights and pedal foot positions. Content from the abstract only.
Participants
n=6 healthy male subjects (abstract: "Six healthy male subjects").
Protocol
Cycling on a bicycle ergometer at different work loads, pedalling rates, saddle heights and pedal foot positions (the specific levels are not given in the abstract, except the condition of the maximum: 120 W, 60 rpm, middle saddle height, anterior foot position).
Inputs to the calculations: a pedal-mounted force transducer, 16-mm cine-film sequences plus biomechanical models of both the patellofemoral joint and the cycling motion.
Key Results
The largest compressive force on the patellofemoral joint, 905 N, or 1.3 times body weight [BW], occurred at 120 W, 60 rpm with an anterior foot position and middle saddle height.
Between quadriceps tendon and intercondylar groove, mean peak compression was 295 N (0.4 BW).
Patellar-tendon and quadriceps-tendon strain forces: 661 N (0.9 BW) and 938 N (1.3 BW).
Patellofemoral joint forces increased with increased work load or decreased saddle height.
Different pedalling rates or foot positions did not significantly change these forces.
Practical Application
"Does a low cadence load my kneecap more?" In 6 healthy men on an ergometer (model-based estimates), patellofemoral joint forces rose with workload and with a lower saddle, but different pedalling rates did not significantly change them; the peak compressive force was 905 N (1.3 times body weight) at 120 W and 60 rpm. In this small sample at modest loads, saddle height and workload moved knee-joint force; cadence did not.
What it does not show: anything about knee pain or injury, people with a patellofemoral problem, or very high-torque efforts (all-out torque work, steep climbs at very low cadence) well above 120 W; with n=6 a cadence effect could be missed.
Inference, not tested here: for a rider with pain at the front of the knee, saddle height and total workload are the levers this study points to; it gives no support for, and no evidence against, avoiding low cadence for that reason.
Not from this paper; the base's own practice: knee pain ends low-cadence and torque work in SYNTH-82; triage and return are in the pain framework.
Limitations
n=6 healthy men; no women, no riders with knee problems.
Joint forces are model estimates from pedal forces and film, not measured inside the joint.
Workloads appear low to moderate (the maximum was at 120 W); the abstract does not give the range of pedalling rates or loads tested, so the null for cadence may not extend to high-torque efforts.
No pain, injury or training outcome; acute measurements only.
Ergometer, 1987 methods (16-mm cine film).
How this entry was checked and changed
Why this level
(mechanistic lab study with no performance or injury outcome; n=6)