scholarly journals Lower energy cost of skeletal muscle contractions in older humans

2010 ◽  
Vol 298 (3) ◽  
pp. R729-R739 ◽  
Author(s):  
Michael A. Tevald ◽  
Stephen A. Foulis ◽  
Ian R. Lanza ◽  
Jane A. Kent-Braun
Keyword(s):  
Energy Cost ◽  
Energetic Cost ◽  
Resonance Spectroscopy ◽  
Age Difference ◽  
Force Frequency ◽  
Older Individuals ◽  
Age Related ◽  
Frequency Relationship ◽  
The Cost

Recent studies suggest that the cost of muscle contraction may be reduced in old age, which could be an important mediator of age-related differences in muscle fatigue under some circumstances. We used phosphorus magnetic resonance spectroscopy and electrically elicited contractions to examine the energetic cost of ankle dorsiflexion in 9 young (Y; 26 ± 3.8 yr; mean ± SD) and 9 older healthy men (O; 72 ± 4.6). We hypothesized that the energy cost of twitch and tetanic contractions would be lower in O and that this difference would be greater during tetanic contractions at f50 (frequency at 50% of peak force from force-frequency relationship) than at 25 Hz. The energy costs of a twitch (O = 0.13 ± 0.04 mM ATP/twitch, Y = 0.18 ± 0.06; P = 0.045) and a 60-s tetanus at 25 Hz (O = 1.5 ± 0.4 mM ATP/s, Y = 2.0 ± 0.2; P = 0.01) were 27% and 26% lower in O, respectively, while the respective force·time integrals were not different. In contrast, energy cost during a 90-s tetanus at f50 (O = 10.9 ± 2.0 Hz, Y = 14.8 ± 2.1 Hz; P = 0.002) was 49% lower in O (1.0 ± 0.2 mM ATP/s) compared with Y (1.9 ± 0.2; P < 0.001). Y had greater force potentiation during the f50 protocol, which accounted for the greater age difference in energy cost at f50 compared with 25 Hz. These results provide novel evidence of an age-related difference in human contractile energy cost in vivo and suggest that intramuscular changes contribute to the lower cost of contraction in older muscle. This difference in energetics may provide an important mechanism for the enhanced fatigue resistance often observed in older individuals.

Individual Leg Muscle Contributions to the Cost of Walking: Effects of Age and Walking Speed

2017 ◽  
Vol 25 (2) ◽  
pp. 295-304 ◽  
Author(s):  
Patricio A. Pincheira ◽  
Lauri Stenroth ◽  
Janne Avela ◽  
Neil J. Cronin
Keyword(s):  
Energy Cost ◽  
Young Group ◽  
Energetic Cost ◽  
Elderly Subjects ◽  
Older Individuals ◽  
Cost Of Transport ◽  
Leg Muscles ◽  
Lower Limb Muscles ◽  
Walking Speeds ◽  
The Cost

This study examined the contributions of individual muscles to changes in energetic cost of transport (COT) over seven walking speeds, and compared results between healthy young and elderly subjects. Twenty six participants (13 young aged 18–30; 13 old aged 70–80) were recruited. COT (O2/kg body mass/km) was calculated by standardizing the mean oxygen consumption recorded during steady state walking. Electromyography signals from 10 leg muscles were used to calculate the cumulative activity required to traverse a unit of distance (CMAPD) for each muscle at each speed. In the old group CMAPD was correlated with COT, presented higher and more variable values, and showed greater increases around optimal speed for all studied muscles. Soleus CMAPD was independent of speed in the young group, but this was not evident with aging. Greater energy cost of walking in older individuals seems to be attributable to increased energy cost of all lower limb muscles.

scholarly journals Contribution of Intramyocellular Lipids to Decreased Computed Tomography Muscle Density With Age

2021 ◽  
Vol 12 ◽  
Author(s):  
Nicholas A. Brennan ◽  
Kenneth W. Fishbein ◽  
David A. Reiter ◽  
Luigi Ferrucci ◽  
Richard G. Spencer
Keyword(s):  
Computed Tomography ◽  
Resonance Spectroscopy ◽  
Older Individuals ◽  
Intramyocellular Lipids ◽  
Muscle Density ◽  
Age Related ◽  
Study Population ◽  
Baltimore Longitudinal Study

Skeletal muscle density, as determined by computed tomography (CT), has been shown to decline with age, resulting in increased frailty and morbidity. However, the mechanism underlying this decrease in muscle density remains elusive. We sought to investigate the role of intramyocellular lipid (IMCL) accumulation in the age-related decline in muscle density. Muscle density was measured using computerized tomography (CT), and IMCL content was quantified using in vivo proton magnetic resonance spectroscopy (1H-MRS). The study population consisted of 314 healthy participants (142 men, 32–98 years) of the Baltimore Longitudinal Study of Aging (BLSA). In addition to IMCL quantification, obesity-related covariates were measured, including body mass index (BMI), waist circumference, and circulating triglyceride concentration. Higher IMCL concentrations were significantly correlated with lower muscle density in older individuals, independent of age, sex, race, and the obesity-associated covariates (p &lt; 0.01). Lower muscle density was also significantly associated with greater age-adjusted IMCL, a variable we constructed using LOESS regression (p &lt; 0.05). Our results suggest that the accumulation of IMCL may be associated with a decrease in muscle density. This may serve to define a potential therapeutic target for treatment of age-associated decreased muscle function.

Speed, stride frequency and energy cost per stride: how do they change with body size and gait?

1988 ◽  
Vol 138 (1) ◽  
pp. 301-318 ◽  
Author(s):  
N. C. Heglund ◽  
C. R. Taylor
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Energy Cost ◽  
Reaction Force ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Published Data ◽  
Frequency Change ◽  
Cost Of Locomotion ◽  
The Cost

In this study we investigate how speed and stride frequency change with body size. We use this information to define ‘equivalent speeds’ for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a gallop all change in the same rather dramatic manner with body size, differing by nine-fold between mice and horses (i.e. all three speeds scale with about the 0.2 power of body mass). Although the absolute speeds differ greatly, the maximum sustainable speed was about 2.6-fold greater than the minimum within a trot, and 2.1-fold greater within a gallop. The frequencies used to sustain the equivalent speeds (with the exception of the minimum trotting speed) scale with about the same factor, the −0.15 power of body mass. Combining this speed and frequency data with previously published data on the energetic cost of locomotion, we find that the mass-specific energetic cost of locomotion is almost directly proportional to the stride frequency used to sustain a constant speed at all the equivalent speeds within a trot and a gallop, except for the minimum trotting speed (where it changes by a factor of two over the size range of animals studied). Thus the energy cost per kilogram per stride at five of the six equivalent speeds is about the same for all animals, independent of body size, but increases with speed: 5.0 J kg-1 stride-1 at the preferred trotting speed; 5.3 J kg-1 stride-1 at the trot-gallop transition speed; 7.5 J kg-1 stride-1 at the preferred galloping speed; and 9.4 J kg-1 stride-1 at the maximum sustained galloping speed. The cost of locomotion is determined primarily by the cost of activating muscles and of generating a unit of force for a unit of time. Our data show that both these costs increase directly with the stride frequency used at equivalent speeds by different-sized animals. The increase in cost per stride with muscles (necessitating higher muscle forces for the same ground reaction force) as stride length increases both in the trot and in the gallop.

Dynamics of photoconversion processes: the energetic cost of lifetime gain in photosynthetic and photovoltaic systems

2021 ◽  
Author(s):  
Robert Godin ◽  
James R. Durrant
Keyword(s):  
Kinetic Model ◽  
Solar Energy ◽  
Energy Conversion ◽  
Energy Cost ◽  
Energetic Cost ◽  
Photovoltaic Systems ◽  
Simple Kinetic Model ◽  
Energy Conversion Systems ◽  
Order Of Magnitude ◽  
The Cost

The energy cost of lifetime gain in solar energy conversion systems is determined from a breadth of technologies. The cost of 87 meV per order of magnitude lifetime improvement is strikingly close to the 59 meV determined from a simple kinetic model.

scholarly journals Differential activation of an identified motor neuron and neuromodulation provide Aplysia's retractor muscle an additional function

2014 ◽  
Vol 112 (4) ◽  
pp. 778-791 ◽  
Author(s):  
Jeffrey M. McManus ◽  
Hui Lu ◽  
Miranda J. Cullins ◽  
Hillel J. Chiel
Keyword(s):  
Motor Neuron ◽  
Muscle Activation ◽  
Retractor Muscle ◽  
Force Frequency ◽  
Additional Function ◽  
Jaw Muscle ◽  
Protraction Phase ◽  
Frequency Relationship

To survive, animals must use the same peripheral structures to perform a variety of tasks. How does a nervous system employ one muscle to perform multiple functions? We addressed this question through work on the I3 jaw muscle of the marine mollusk Aplysia californica's feeding system. This muscle mediates retraction of Aplysia's food grasper in multiple feeding responses and is innervated by a pool of identified neurons that activate different muscle regions. One I3 motor neuron, B38, is active in the protraction phase, rather than the retraction phase, suggesting the muscle has an additional function. We used intracellular, extracellular, and muscle force recordings in several in vitro preparations as well as recordings of nerve and muscle activity from intact, behaving animals to characterize B38's activation of the muscle and its activity in different behavior types. We show that B38 specifically activates the anterior region of I3 and is specifically recruited during one behavior, swallowing. The function of this protraction-phase jaw muscle contraction is to hold food; thus the I3 muscle has an additional function beyond mediating retraction. We additionally show that B38's typical activity during in vivo swallowing is insufficient to generate force in an unmodulated muscle and that intrinsic and extrinsic modulation shift the force-frequency relationship to allow contraction. Using methods that traverse levels from individual neuron to muscle to intact animal, we show how regional muscle activation, differential motor neuron recruitment, and neuromodulation are key components in Aplysia's generation of multifunctionality.

scholarly journals Human skeletal muscle metabolic economy in vivo: effects of contraction intensity, age, and mobility impairment

2014 ◽  
Vol 307 (9) ◽  
pp. R1124-R1135 ◽  
Author(s):  
Anita D. Christie ◽  
Anne Tonson ◽  
Ryan G. Larsen ◽  
Jacob P. DeBlois ◽  
Jane A. Kent
Keyword(s):  
Functional Mobility ◽  
Older Individuals ◽  
Mobility Impairment ◽  
Cross Sectional ◽  
Age Related ◽  
Creatine Kinase Reaction ◽  
Voluntary Contractions ◽  
In Vivo Effects ◽  
Muscle Cross Sectional Area

We tested the hypothesis that older muscle has greater metabolic economy (ME) in vivo than young, in a manner dependent, in part, on contraction intensity. Twenty young (Y; 24 ± 1 yr, 10 women), 18 older healthy (O; 73 ± 2, 9 women) and 9 older individuals with mild-to-moderate mobility impairment (OI; 74 ± 1, 7 women) received stimulated twitches (2 Hz, 3 min) and performed nonfatiguing voluntary (20, 50, and 100% maximal; 12 s each) isometric dorsiflexion contractions. Torque-time integrals (TTI; Nm·s) were calculated and expressed relative to maximal fat-free muscle cross-sectional area (cm2), and torque variability during voluntary contractions was calculated as the coefficient of variation. Total ATP cost of contraction (mM) was determined from flux through the creatine kinase reaction, nonoxidative glycolysis and oxidative phosphorylation, and used to calculate ME (Nm·s·cm−2·mM ATP−1). While twitch torque relaxation was slower in O and OI compared with Y ( P ≤ 0.001), twitch TTI, ATP cost, and economy were similar across groups ( P ≥ 0.15), indicating comparable intrinsic muscle economy during electrically induced isometric contractions in vivo. During voluntary contractions, normalized TTI and total ATP cost did not differ significantly across groups ( P ≥ 0.20). However, ME was lower in OI than Y or O at 20% and 50% MVC ( P ≤ 0.02), and torque variability was greater in OI than Y or O at 20% MVC ( P ≤ 0.05). These results refute the hypothesis of greater muscle ME in old age, and provide support for lower ME in impaired older adults as a potential mechanism or consequence of age-related reductions in functional mobility.

Biaxial Mechanical Testing of Single Annulus Fibrosus Layers

2010 ◽  
Author(s):  
J. P. Rys ◽  
A. M. Ellingson ◽  
D. J. Nuckley ◽  
V. H. Barocas
Keyword(s):  
Intervertebral Disc ◽  
Annulus Fibrosus ◽  
Spinal Nerve ◽  
Older Individuals ◽  
Physical Trauma ◽  
Age Related ◽  
Biaxial Mechanical Testing ◽  
Partial Displacement ◽  
Outer Annulus Fibrosus

The intervertebral disc (IVD), consisting of the inner nucleus pulposus and the outer annulus fibrosus, is subjected to multiaxial stress in vivo. The disc undergoes degenerative changes that account for impairment and disability in middle-aged and older individuals.4 In addition to age-related degeneration, the intervertebral disc is subject to the development of lesions due to partial displacement or rupture of the annulus fibrosus. Such occurrences, typically resulting from physical trauma, can yield disabling effects from impingement on spinal nerve structures. A greater understanding of the IVD and how it functions mechanically is crucial in prevention and repair of debilitating spinal disorders.

scholarly journals Bacopa monnierias an Antioxidant Therapy to Reduce Oxidative Stress in the Aging Brain

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Tamara Simpson ◽  
Matthew Pase ◽  
Con Stough
Keyword(s):  
Oxidative Stress ◽  
Cognitive Function ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Bacopa Monnieri ◽  
Aging Brain ◽  
Resonance Spectroscopy ◽  
Age Related

The detrimental effect of neuronal cell death due to oxidative stress and mitochondrial dysfunction has been implicated in age-related cognitive decline and neurodegenerative disorders such as Alzheimer’s disease. The Indian herbBacopa monnieriis a dietary antioxidant, with animal andin vitrostudies indicating several modes of action that may protect the brain against oxidative damage. In parallel, several studies using the CDRI08 extract have shown that extracts ofBacopa monnieriimprove cognitive function in humans. The biological mechanisms of this cognitive enhancement are unknown. In this review we discuss the animal studies andin vivoevidence forBacopa monnierias a potential therapeutic antioxidant to reduce oxidative stress and improve cognitive function. We suggest that future studies incorporate neuroimaging particularly magnetic resonance spectroscopy into their randomized controlled trials to better understand whether changes in antioxidant statusin vivocause improvements in cognitive function.

In Vivo Brain Glutathione is Higher in Older Age and Correlates with Mobility

2020 ◽  
Author(s):  
K. E. Hupfeld ◽  
H. W. Hyatt ◽  
P. Alvarez Jerez ◽  
M. Mikkelsen ◽  
C. J. Hass ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Older Adults ◽  
Motor Performance ◽  
Resonance Spectroscopy ◽  
Younger Adults ◽  
Age Related ◽  
Brain Oxidative Stress ◽  
Brain Antioxidants ◽  
Insight Into

AbstractBrain markers of oxidative damage increase with advancing age. In response, brain antioxidant levels may also increase with age, although this has not been well investigated. Here we used edited magnetic resonance spectroscopy to quantify endogenous levels of glutathione (GSH, one of the most abundant brain antioxidants) in 37 young (mean: 21.8 (2.5) years; 19 F) and 23 older adults (mean: 72.8 (8.9) years; 19 F). Accounting for age-related atrophy, we identified higher frontal and sensorimotor GSH levels for the older compared to the younger adults. For the older adults only, higher sensorimotor (but not frontal) GSH was correlated with poorer balance, gait, and manual dexterity. This suggests a regionally-specific relationship between higher brain oxidative stress levels and motor performance declines with age. We suggest these findings reflect a compensatory upregulation of GSH in response to increasing brain oxidative stress with normal aging. Together, these results provide insight into age differences in brain antioxidant levels and implications for motor function.

scholarly journals Effects of Nitric Oxide Synthase Inhibition on Basal Function and the Force-Frequency Relationship in the Normal and Failing Human Heart In Vivo

Circulation ◽  
2001 ◽  
Vol 104 (19) ◽  
pp. 2318-2323 ◽  
Author(s):  
James M. Cotton ◽  
Mark T. Kearney ◽  
Philip A. MacCarthy ◽  
Richard M. Grocott-Mason ◽  
Dougal R. McClean ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Human Heart ◽  
Force Frequency ◽  
Frequency Relationship ◽  
Oxide Synthase
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