‍Background/Purpose 

Patellar tendinopathy is common amongst athletes and is often associated with reduced eccentric strength and power during various movements and tests. Isokinetic dynamometers are often used for eccentric testing, but it is usually not feasible to test sport-relevant actions in this manner. Flywheel devices can allow for neuromuscular testing within movements that are similar to sporting actions. The purpose of this study was to determine if flywheel testing could be a feasible way to assess neuromuscular performance in athletes for the purposes of guiding treatment and diagnosis of patellar tendinopathy. 

Methods 

40 male and female Olympic athletes across various jumping sports were divided into four subgroups: 1) female athletes with patellar tendinopathy (Female PT), 2) female athletes without patellar tendinopathy (Female non-PT), 3) Male athletes with patellar tendinopathy (Male PT), and 4) male athletes without patellar tendinopathy (Male non-PT). Participants performed 3 sets of 10 reps (plus 2 warm-up reps) of flywheel half-squats, each with a different inertial load (0.050, 0.075, and 0.100 kgm²). Measures of concentric and eccentric peak power, the ECC/CON power ratio, and peak movement speed were recorded and compared between 1) Female PT vs Female non-PT and 2) Male PT vs Male non-PT groups.  

Results 

Here is a summary of key results: 

• Both female and male PT groups had lower eccentric power than their non-PT counterparts across all 3 inertial loads (differences ranged from 17.9 – 57%). 

• The non-PT groups produced greater eccentric power as inertial load increased, while the PT groups had similar eccentric power across loads.  

• Despite differences in eccentric power, concentric power was statistically similar between the PT and non-PT groups.  

• The non-PT groups achieved eccentric-to-concentric power ratios >1.0 for all inertial loads, while the PT groups did not. This resulted in statistically significant differences between the non-PT and PT groups for the ratio values.  

• The PT groups had significantly slower movement speeds than the non-PT groups, particularly at the lowest inertial load.  

Key Takeaways 

The main finding of this study was that athletes with patellar tendinopathy produced similar concentric power, significantly lower eccentric power outputs and movement speeds than their healthy counterparts. This aligns with prior isokinetic testing studies, which has found reduced eccentric strength and power in athletes with patellar tendinopathy and may be due to compromised eccentric capabilities and motor control which requires them to manage eccentric loading differently than healthy athletes. Testing eccentric power and speed during flywheel half-squats may be a realistic and feasible way to benchmark healthy athletes, and to inform rehabilitation and return to play in athletes with patellar tendinopathy.