Effects of age and physical activity status on redistribution of joint work during walking

Abstract

During walking older adults rely less on ankle and more on hip work than young adults. Disproportionate declines in plantarflexor strength may be a mechanism underlying this proximal work redistribution. We tested the hypothesis that proximal redistribution is more apparent in older compared to young adults and in sedentary compared to active individuals over multiple walking speeds. We recruited 18 young (18-35 yrs) and 17 older (65-80 yrs) physically active and sedentary adults. Participants completed five trials at four walking speeds as marker positions and ground reaction forces were collected. Sagittal plane net joint moments were computed using inverse dynamics. Instantaneous joint powers for the ankle, knee, and hip were computed as products of net joint moments and joint angular velocities. Positive joint work was computed by integrating hip, knee, and ankle joint powers over time in early, mid, and late stance, respectively. Relative joint work was expressed as a percentage of total work. Isokinetic strength of lower limb flexor and extensor muscles was measured. Older adults had lower relative ankle (p=0.005) and higher relative hip (p=0.007) work than young adults for multiple speeds. Non-significant trends (p<0.10) indicating sedentary participants had lower relative ankle (p=0.068) and higher relative hip work (p=0.087) than active adults were observed. Age-related differences in plantarflexor strength were not disproportionate compared to strength differences in knee and hip musculature. Age influenced proximal work redistribution over multiple walking speeds. Physical activity status showed a similar trend for proximal work redistribution, but failed to reach statistical significance.

Age-related changes to triceps surae muscle-subtendon interaction dynamics during walking

“…Moreover, in response to increased mechanical demand for forward propulsion, older adults walked with significantly smaller peak ankle power than young adults (e.g., − 24% with impeding forces). However, contrary to several prior studies, we did not observe an effect of age on peak ankle moment or positive ankle push-off work during walking, likely as a result of our relatively slow range of walking speeds 33 . Yet, similar to our findings, Knaus et al revealed that older adults who walked with similar ankle moment generation to younger adults presented with deleterious changes in AT structure–function relations that are not measurable using conventional biomechanical analyses alone 34 .…”

Predictive neuromechanical simulations indicate why walking performance declines with ageing

“…A4A). The elderly model uses more actuation of the hip flexors (HFL) and less actuation of the ankle extensors (GAS, gastrocnemius; SOL, soleus), which is in line with what is observed in elderly people (Judge et al 1996;Monaco et al 2009;Schmitz et al 2009;Buddhadev & Martin, 2016). Although the change in muscle properties (M 2 ) does not have much effect on the total COT, it is the main contributor to the change in muscle coordination (Fig.…”

Gait Analysis of Patients After Allogeneic Hematopoietic Cell Transplantation Reveals Impairments of Functional Performance

“…Degeneration processes such as aging can modify this alteration: for example, an age-associated strength decrease may lead to a distal-to-proximal (ankle to hip) shift of joint work 39-41 that can affect locomotor ability. 42,43 Naturally, the neuromuscular system’s aging implies a continuous functional decline caused by time-dependent, accumulated cellular damage 44,45 that results in age-related loss of muscle mass and function. This loss is strongly related to physical disability, 46,47 functional impairments, 48 and even mortality, 49 whereby the loss of strength contributes proportionally more to predicting disability than does muscle mass.…”