No specific inclusion criterion was stated regarding the participants, but studies including participants with any neurological disease that may cause spasticity of the muscle were excluded. The mean age of participants included in the trials was between 23 and 40 years. With the exception of one study in women only, all studies included women and men. None of the included trials included participants with lower limb injuries.
Studies were eligible if they compared the effect of static calf muscle stretching with no stretching. Emphasis was on the techniques used in home programmes. Studies that used the other leg as a control were excluded. Stretching technique could include weight-bearing or non-weight-bearing stretches with the knee flexed or extended. Trials involving devices to assist mechanical stretch (such as splints or pulleys with weights) were included, whereas those involving devices to assist the muscles’ physiological ability to stretch (such as ultrasound or heat packs) were excluded. Of the included studies, four examined weight-bearing static stretch and one non-weight-bearing static stretch assisted by weight. The duration of the stretch was between 30 seconds and 5 minutes (one trial with four times 20 seconds with 10 seconds rest in between). The duration of the training ranged from a single session to 5 days a week for 6 weeks.
Studies were eligible if they assessed ankle joint range of motion on both weight-bearing and non-weight-bearing conditions (goniometers, electronic inclinometers). Measurements during walking or running were also included. The included trials measured ankle dorsiflexion both actively and passively, weight-bearing and non-weight-bearing, and with the knee extended or flexed. Most trials carried out measurements immediately after stretching, with the exception of one trial in which there was an interval of between 60 and 72 hours. More trials provided results for the active measurement of ankle dorsiflexion, so in trials providing with data from active and passive measurement, only data from active measurement were pooled.
Studies were eligible if they were randomised or quasi-randomised controlled trials. Crossover trials were excluded.
One reviewer conducted all the searches and two reviewers were involved in selecting the studies. There was no disagreement on study eligibility.