Acute Effects of the weight-bearing dorsiflexion lunge stretch on gastrocnemius flexibility assessed using real-time ultrasound

Abstract

Objectives: To examine the acute effects of the weight-bearing dorsiflexion lunge stretch (WDL) on the flexibility of the gastrocnemius muscle-tendon unit using real time ultrasound (RTUS). Participants: Ten healthy males were randomly assigned to one of two groups. Interventions: Group 1 (n=5) completed three WDL stretches on the dominant leg of 30s duration, once daily, for four days. Group 2 (n=5) completed the same programme twice daily. Participant's non-dominant leg acted as control. Outcome measures: Elongation of the stretched gastrocnemius muscle-tendon unit was recorded using RTUS before stretching, after one set of stretches, and 24 hours after the final set of stretches. Range of motion (ROM) was recorded and torque was calculated as an index of stiffness. Results: Wilcoxon Signed Ranks tests were used to test for differences within groups. Mann-Whitney tests were used to test for differences between groups. No significant changes in length, ROM or stiffness occurred after stretching in either group although ankle stiffness appeared to decrease. No significant differences were found between groups. Conclusions: Frequently prescribed parameters, used clinically for stretching the gastrocnemius muscle, were shown to have no short-term effect on the flexibility of this muscle for a healthy sample of participants. RTUS measurements were found to be a reliable means of assessing changes in flexibility and should be considered for further research in this area. A repeat study is required, using a larger sample size and involving participants with decreased dorsiflexion ROM following injury.