Relationship Between Gastrocnemius Muscle Stiffness, Physical Performance, and Muscle Strength in Older Adults

Purpose: Age-related declines in muscle function have been associated with reduced mobility and impaired physical performance in older adults.The gastrocnemius muscle contributes to gait propulsion and postural control, but its relationship with the functional performance remains unclear.This study examined the associations of gastrocnemius muscle stiffness with physical performance and muscle strength in older adults.Methods: Twenty healthy older adults (8 men and 12 women; mean age, 73.2± 4.7 years) participated in this cross-sectional study.Gastrocnemius muscle stiffness was measured using a MyotonPRO.Physical performance was assessed using the Short Physical Performance Battery (SPPB) and the Five Times Sit-to-Stand Test (5XSST), while the muscle strength was evaluated using hand grip strength (HS).Spearman's rank correlation analysis was used to assess the relationships between variables.Results: Right gastrocnemius muscle stiffness showed a positive correlation with the SPPB total score (ρ= 0.893, p< 0.001) and a negative correlation with 5XSST performance time (ρ= -0.785, p< 0.001).Left gastrocnemius muscle stiffness was positively correlated with the SPPB total score (ρ= 0.662, p = 0.001) and HS (ρ= 0.480, p = 0.032) and negatively correlated with the 5XSST performance time (ρ= -0.615, p= 0.004).The SPPB total score showed a significant positive correlation with HS (ρ= 0.550, p= 0.009) and a negative correlation with 5XSST performance time (ρ= -0.897, p< 0.001).Conclusion: Gastrocnemius muscle stiffness revealed significant associations with physical performance in older adults, while a significant association with hand grip strength was observed only for the left gastrocnemius muscle.These findings suggest that an assessment of gastrocnemius muscle stiffness may provide supplementary information for understanding physical performance in older adults.