Normative Parameters of Gastrocnemius Muscle Stiffness and Associations with Patient Characteristics and Function.
Larisa R Hoffman, Shane L Koppenhaver, Cameron W MacDonald and 5 others
PMID 33604133WHAT IT FOUND
In healthy adults, resting gastrocnemius stiffness was lower than stiffness during a heel raise, and men had higher stiffness than women.
Stiffness was related to plantarflexion force and step length, not to age, BMI, race, exercise, or gait speed.
Key findings
01The study averaged three stiffness measures in each position and analysed 102 adults aged 18 to 50, including 44 men and 58 women with mean age 26.00 years; mean stiffness was 300.1 N/m at rest and 504.6 N/m in the contracted state.
02Men had higher mean stiffness than women in both states: 350.3 versus 261.95 N/m at rest, and 662.6 versus 384.8 N/m in the contracted state.
03Higher stiffness was related to greater plantarflexion force and longer step length, while age, BMI, race, exercise frequency, exercise duration, and gait velocity showed no relation.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
All participants were healthy adults aged 18 to 50, and people with recent injury or inability to heel raise were excluded, so the values may not apply to patients with musculoskeletal impairments or older adults. The sample was mostly Caucasian (72.1%) and included no African American participants, so race-related findings may not generalize. Exercise frequency and duration were grouped into broad categories, so the study may not detect real differences between activity levels. The design was cross-sectional and single-group, so it shows associations at a single time point, not that stiffness causes force or gait differences.
The easy way to misread this
Do not treat these stiffness values as diagnostic cutoffs for injury. The study measured healthy adults aged 18 to 50 and excluded people with lower-extremity injury, and it did not test whether changing stiffness changes function.