Increased supraspinatus tendon thickness following fatigue loading in rotator cuff tendinopathy: potential implications for exercise therapy.

Background/aim Exercise imparts a load on tendon
tissue that leads to changes in tendon properties. Studies
suggest that loading immediately reduces tendon
thickness, with a loss of this response in symptomatic
tendinopathy. No studies investigating the response of
tendon dimensions to load for the rotator cuff tendons
exist. This study aimed to examine the short-term effect of
loading on the thickness of the supraspinatus tendon and
acromiohumeral distance those with and without rotator
cuff tendinopathy.
Methods: Participants were 20 pain free controls,
and 23 people with painful rotator cuff tendinopathy.
Supraspinatus tendon thickness and acromiohumeral
distance were measured using ultrasound scans before,
and at three time points after loading (1, 6 and 24 hours).
Loading involved isokinetic eccentric and concentric
external rotation and abduction.
Result: There was a significant increase in
supraspinatus tendon thickness in the pain group at 1 (7%,
Δ=0.38, 95% CI 0.19 to 0.57) and 6 hours (11%, Δ=0.53,
95% CI 0.34 to 0.71), although only the 6 hours difference
exceeded minimal detectable difference. In contrast,
there was a small non-significant reduction in thickness
in controls. The acromiohumeral distance reduced
significantly in both groups at 1 hour (controls: Δ=0.64,
95% CI 0.38 to 0.90; pain: Δ=1.1, 95% CI 0.85 to 1.33),
with a larger change from baseline in the pain group.
Conclusion Those diagnosed with painful supraspinatus
tendinopathy demonstrated increased thickening with
delayed return to baseline following loading. Rehabilitation
professionals may need to take into account the impact
of loading to fatigue when planning rehabilitation
programmes.