80 THE METABOLIC COST OF TWO RANGES OF ARM POSITION HEIGHT WITH AND WITHOUT HAND WEIGHTS DURING LOW IMPACT AEROBIC DANCE

Older adults walk slower and with a higher metabolic energy expenditure than younger adults. In this review, we explore the hypothesis that age-related declines in Achilles tendon stiffness increase the metabolic cost of walking due to less economical calf muscle contractions and increased proximal joint work. This viewpoint may motivate interventions to restore ankle muscle-tendon stiffness, improve walking mechanics, and reduce metabolic cost in older adults.

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Sensory feedback-dependent coding of arm position in local field potentials of the posterior parietal cortex

Scientific Reports ◽

10.1038/s41598-021-88278-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Paul VanGilder ◽

Ying Shi ◽

Gregory Apker ◽

Christopher A. Buneo

Keyword(s):

Local Field ◽

Sensory Feedback ◽

Posterior Parietal Cortex ◽

Spectral Power ◽

Field Potential ◽

Beta Activity ◽

Beta Band ◽

Arm Position ◽

Multisensory Interactions ◽

Spiking Activity

AbstractAlthough multisensory integration is crucial for sensorimotor function, it is unclear how visual and proprioceptive sensory cues are combined in the brain during motor behaviors. Here we characterized the effects of multisensory interactions on local field potential (LFP) activity obtained from the superior parietal lobule (SPL) as non-human primates performed a reaching task with either unimodal (proprioceptive) or bimodal (visual-proprioceptive) sensory feedback. Based on previous analyses of spiking activity, we hypothesized that evoked LFP responses would be tuned to arm location but would be suppressed on bimodal trials, relative to unimodal trials. We also expected to see a substantial number of recording sites with enhanced beta band spectral power for only one set of feedback conditions (e.g. unimodal or bimodal), as was previously observed for spiking activity. We found that evoked activity and beta band power were tuned to arm location at many individual sites, though this tuning often differed between unimodal and bimodal trials. Across the population, both evoked and beta activity were consistent with feedback-dependent tuning to arm location, while beta band activity also showed evidence of response suppression on bimodal trials. The results suggest that multisensory interactions can alter the tuning and gain of arm position-related LFP activity in the SPL.

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Reducing the metabolic energy of walking and running using an unpowered hip exoskeleton

Journal of NeuroEngineering and Rehabilitation ◽

10.1186/s12984-021-00893-5 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Tiancheng Zhou ◽

Caihua Xiong ◽

Juanjuan Zhang ◽

Di Hu ◽

Wenbin Chen ◽

...

Keyword(s):

Energy Consumption ◽

Design Method ◽

Metabolic Cost ◽

Metabolic Energy ◽

Spring Stiffness ◽

Spatiotemporal Parameters ◽

The Common ◽

Hip Flexion ◽

Optimal Stiffness ◽

Insight Into

Abstract Background Walking and running are the most common means of locomotion in human daily life. People have made advances in developing separate exoskeletons to reduce the metabolic rate of walking or running. However, the combined requirements of overcoming the fundamental biomechanical differences between the two gaits and minimizing the metabolic penalty of the exoskeleton mass make it challenging to develop an exoskeleton that can reduce the metabolic energy during both gaits. Here we show that the metabolic energy of both walking and running can be reduced by regulating the metabolic energy of hip flexion during the common energy consumption period of the two gaits using an unpowered hip exoskeleton. Methods We analyzed the metabolic rates, muscle activities and spatiotemporal parameters of 9 healthy subjects (mean ± s.t.d; 24.9 ± 3.7 years, 66.9 ± 8.7 kg, 1.76 ± 0.05 m) walking on a treadmill at a speed of 1.5 m s−1 and running at a speed of 2.5 m s−1 with different spring stiffnesses. After obtaining the optimal spring stiffness, we recruited the participants to walk and run with the assistance from a spring with optimal stiffness at different speeds to demonstrate the generality of the proposed approach. Results We found that the common optimal exoskeleton spring stiffness for walking and running was 83 Nm Rad−1, corresponding to 7.2% ± 1.2% (mean ± s.e.m, paired t-test p < 0.01) and 6.8% ± 1.0% (p < 0.01) metabolic reductions compared to walking and running without exoskeleton. The metabolic energy within the tested speed range can be reduced with the assistance except for low-speed walking (1.0 m s−1). Participants showed different changes in muscle activities with the assistance of the proposed exoskeleton. Conclusions This paper first demonstrates that the metabolic cost of walking and running can be reduced using an unpowered hip exoskeleton to regulate the metabolic energy of hip flexion. The design method based on analyzing the common energy consumption characteristics between gaits may inspire future exoskeletons that assist multiple gaits. The results of different changes in muscle activities provide new insight into human response to the same assistive principle for different gaits (walking and running).

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