Which muscles compromise human locomotor performance with age?

Abstract

Ageing leads to a progressive decline in human locomotor performance. However, it is not known whether this decline results from reduced joint moment and power generation of all lower limb muscle groups or just some of them. To further our understanding of age-related locomotor decline, we compare the amounts of joint moments and powers generated by lower limb muscles during walking (self-selected), running (4 m s 21) and sprinting (maximal speed) among young, middle-aged and old adults. We find that age-related deficit in ankle plantarflexor moment and power generation becomes more severe as locomotion change from walking to running to sprinting. As a result, old adults generate more power at the knee and hip extensors than their younger counterparts when walking and running at the same speed. During maximal sprinting, young adults with faster top speeds demonstrate greater moments and powers from the ankle and hip joints, but interestingly, not from the knee joint when compared with the middle-aged and old adults. These findings indicate that propulsive deficit of ankle contributes most to the age-related locomotor decline. In addition, reduced muscular output from the hip rather than from knee limits the sprinting performance in older age.

Slower Walking Speed in Older Men Improves Triceps Surae Force Generation Ability

“…Reduced ankle plantarflexion peak power in the late push-off phase of walking is a consistent finding in both healthy and mobility limited older compared to young adults (10, 23,30), and it seems that impairments in plantarflexor force and power generation contribute to a reduction in preferred walking speed in older adults (29). Tendinous tissues (tendon and aponeurosis, TT) elasticity greatly affects muscle function of the main plantarflexor, triceps surae, due to a large tendon to muscle fiber length ratio (41).…”

“…Thus, improvement in triceps surae contractile conditions for force generation and consequential decrease in muscle activation to maintain required level of force generation may affect total energy cost of walking and hence drive the selection of slower walking speeds in older adults. In addition, it has been shown that older adults compensate for reduced plantarflexor power and work output during push-off by increasing the use of hip extensors in early stance (10), which may operate with greater reserve capacity (23). However, this distal to proximal shift in muscular strategy, where power generation of plantarflexors that can utilize a catapult action due to a long Achilles tendon (21) is replaced by power generation from an MTU with a short tendon, may increase energy cost of walking due to unfavorable muscle shortening velocities of the muscles providing the positive power (37).…”

Depth-dependent variations in Achilles tendon deformations with age are associated with reduced plantarflexor performance during walking

“…PLANTARFLEXOR PERFORMANCE (i.e., net ankle joint kinetics) during the push-off phase of walking decreases precipitously in old age (6,7,17,21,38). This biomechanical change is often implicated in and may precede the age-related slowing of preferred walking speed, which in turn negatively affects old adults' health and independence (13,31).…”

“…Our findings: 1) demonstrate a potential role for nonuniform AT deformations in governing gastrocnemius and soleus muscle-tendon function and 2) allude to altered tendon behavior that may contribute to the age-related reduction in plantarflexor performance during walking. ultrasound; gait; triceps surae; kinetics; elderly PLANTARFLEXOR PERFORMANCE (i.e., net ankle joint kinetics) during the push-off phase of walking decreases precipitously in old age (6,7,17,21,38). This biomechanical change is often implicated in and may precede the age-related slowing of preferred walking speed, which in turn negatively affects old adults' health and independence (13, 31).…”

Prediction of active peak force using a multilayer perceptron

“…It seems plausi- ble that the accuracy of the current method is sufficient for discriminating between normal and abnormal peak vertical GRF values of recreational runners. As an example, GRF peak values of young, middle-aged, and old athletes were measured and compared in [15]. By calculating the 95th percentiles of the values for each age category, we obtained estimates of the thresholds for abnormal peak forces from these data sets.…”