Effects of an exercise program on calf muscle characteristics in patients with Achilles tendinopathy.

UNLABELLED: Objective in participants with Achilles tendinopathy. Additionally, it explored the relationships between muscle adaptations and functional outcomes.

DESIGN

Prospective observational study.

SETTING

Laboratory-based assessment.

PARTICIPANTS

Thirty-five participants with Achilles tendinopathy completed a 16-week exercise program.

MAIN OUTCOME MEASURES: Muscle EI of the medial (MG) and lateral gastrocnemius (LG) and soleus (SOL) was assessed using ImageJ. B-mode ultrasound was used to measure MGCSA, LGCSA, and SOL thickness at baseline and post-intervention. Functional outcomes included single-leg countermovement jump (CMJ), drop CMJ, and heel-rise (HR) endurance tests.

RESULTS

MGEI and LGEI significantly decreased on both symptomatic sides (p < 0.05, d = 0.5-0.8). MGCSA and LGCSA increased (p < 0.05, d = 0.3), while SOLEI and SOL thickness did not change (p > 0.05). Heel-rise work improved (p < 0.05, d = 0.4), but jump heights did not. Regression analysis showed that age, BMI, and muscle changes did not predict improvements in HR work (Adjusted R2 = 0.11, p > 0.05).

CONCLUSIONS

The exercise program reduced muscle EI and increased hypertrophy but did not significantly improve calf endurance. Further research should explore how muscle adaptations affect function in Achilles tendinopathy rehabilitation.