Ankle flexor/extensor strength and muscle density are complementary determinants of balance during dual‐task engagement: The ankle quality study

Abstract

Background This study investigated relative contributions of ankle flexor torque, muscle size, and density on balance and falls. Methods Men and women ≥50 years of age completed a peripheral quantitative computed tomography scan of the mid‐leg to quantify muscle density (MD) and cross‐sectional area; Biodex dynamometry to evaluate maximal isometric ankle flexor torque; and a single‐leg balance test on a force platform with/without eyes closed and cognitive task. Ankle flexor torque, muscle size, and density individually, together, or as interactions were examined for associations with balance (mean step duration, steps/trial) in general linear models, or with falls in Poisson regression, adjusting for age, sex, BMI, glucocorticoid use, osteoarthritis, and physical activity. Visuo‐cognitive conditions were compared. Results Among 105 participants (age: 63.3 ± 9.9 years, BMI: 25.8 ± 5.4 kg/m2, 77.1% female), 41.8% experienced ≥1 fall in the last year. Balance on one leg was dependent on ankle flexor torque when eyes were open (r = −0.220 to −0.284) and on having leaner mid‐leg muscles when eyes were closed (r = −0.123 to −0.142); cognitive challenge blunted these correlations. Individuals with leaner muscles tended to rely more on plantarflexors than dorsiflexors. A 2% lower step‐free fraction in the eyes‐closed paradigm associated with having 1 additional fall [−0.701(−1.235, −0.167)], but neither torque, muscle density, nor size related to number of falls. Conclusions Among ambulatory adults, ankle flexor torque and muscle density showed an interactive influence on balance that depended on visuo‐cognitive input. The complementary roles of torque and muscle density on balance suggest redundancy is important under dual‐tasking conditions.

The Influence of Knee Extensor and Ankle Plantar Flexor Strength on Single-Leg Standing Balance in Older Women

“…Knee extensor (KE) and ankle plantar flexor (AP) muscle strengths are important for standing balance as they are responsible for maintaining upright posture and pushing the body forward and upward [ 17 , 18 , 19 , 20 ]. In contrast, knee flexor and ankle dorsiflexor muscles play a secondary role in maintaining balance, with their contribution being relatively small [ 19 , 21 ]. The KE muscles, including the quadriceps, work to extend the knee joint and prevent it from collapsing [ 22 ], while the AP muscles, including the gastrocnemius and soleus, work to maintain ankle stability and prevent the foot from rolling inward or outward [ 17 ].…”