Foot Posture, Strength, Performance, and Postural Control in Isolated Gastrocnemius Tightness

Since the gastrocnemius muscle spans both joints, the kinematics of the ankle joint are influenced by knee flexion. According to Kendall & McCreary's assessment of normal joint motion angles, when the knee joint is in extension, the passive dorsiflexion angle of the ankle is approximately 20°, and with knee flexion, the angle can approach 30° due to the relaxation of the gastrocnemius. During the midstance phase of walking, the ankle joint allows for 8-10° of dorsiflexion movement. The evaluation of gastrocnemius muscle tightness is conducted using the Silfverskiold method. However, there are variations in the definitions proposed for the detection of isolated gastrocnemius tightness. In our investigation, when ankle dorsiflexion rises by at least 10° more in knee flexion than knee extension, isolated gastrocnemius tightness will be taken into account.

Isolated gastrocnemius tightness during walking can result in compensatory effects on the lower extremity and foot, causing biomechanical changes such as pes planus, talus eversion, rearfoot pronation, and various symptoms such as plantar fasciitis, leg pain, metatarsalgia, and Achilles tendinopathy. The association between increased rearfoot pronation and isolated gastrocnemius tightness has been demonstrated in the literature. Regardless of the etiology of rearfoot pronation, adaptive isolated gastrocnemius shortening will occur in conjunction with talar plantar flexion. Isolated gastrocnemius tightness causing plantar flexion at the ankle joint and pronation at the subtalar joint also hinders the normal distribution of load on the plantar surface during weight-bearing. Reviewing the literature, it is observed that the effects of isolated gastrocnemius tightness on foot posture, functional parameters, and gait dynamics, especially rearfoot pronation, are reported.

Studies on gastrocnemius tightness in healthy children are limited, but there is evidence that ankle dorsiflexion decreases with age in children. While it is unknown whether gastrocnemius shortening is a normal finding in children, recurrent leg pain is common in children. Additionally, flexible flatfoot is considered a normal observation in developing children, and it is known that the medial longitudinal arch develops in the first ten years of life. Both foot morphology and ankle dorsiflexion change in developing children, but it is unknown whether there is a relationship between the two.

In the literature, there is no study evaluating foot posture, muscle strength, functional performance, and postural control in children with isolated gastrocnemius muscle shortening. In our study, we plan to assess postural control using computerized dynamic posturography (Biodex Balance System), lower extremity muscle strength using a hand-held dynamometer, foot posture using the Foot Posture Index (FPI-6), and functional performance using single-leg and double-leg hop tests in healthy children with isolated gastrocnemius muscle shortening.

Inclusion criteria

Study group

• Presence of bilateral isolated gastrocnemius tightness (The test is considered positive when ankle dorsal flexion dorsiflexion increases over a minimum of 10 degrees with the knee flexed than the knee extension.
• Being between 7-16 years of age
• Body mass index within normal limits (18.5-24.9 kg/m2) Exclusion criteria
• Presence of high femoral anteversion, internal tibial torsion, and metatarsus adductus
• Presence of hypermobility (Beighton score >4 and above)
• Leg length discrepancy
• Presence of any neurological, rheumatic, musculoskeletal, metabolic, and connective tissue disease
• History of pain, deformity, or surgery associated with the vertebral column and lower extremities
• Presence of cognitive, mental, and/or severe psychiatric illness
• Participation in any exercise program or sportive activity in the last six months

For the control group, the same inclusion/exclusion criteria will be accepted except that the bilateral Silfverskiold test is negative.