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Age- and gender-related changes in contractile properties of non-atrophied EDL muscle.

Chan S, Head SI - PLoS ONE (2010)

Bottom Line: However, it is not entirely clear whether these changes in contractile properties can occur before there is significant atrophy, and whether males and females are affected differently.In the properties of absolute force and muscle relaxation times, females were affected by ageing to a greater extent than males.Our findings provide further insight into the muscle atrophy, weakness and fatiguability experienced by the elderly.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia.

ABSTRACT

Background: In humans, ageing causes skeletal muscles to become atrophied, weak, and easily fatigued. In rodent studies, ageing has been associated with significant muscle atrophy and changes in the contractile properties of the muscles. However, it is not entirely clear whether these changes in contractile properties can occur before there is significant atrophy, and whether males and females are affected differently.

Methods and results: We investigated various contractile properties of whole isolated fast-twitch EDL muscles from adult (2-6 months-old) and aged (12-22 months-old) male and female mice. Atrophy was not present in the aged mice. Compared with adult mice, EDL muscles of aged mice had significantly lower specific force, longer tetanus relaxation times, and lower fatiguability. In the properties of absolute force and muscle relaxation times, females were affected by ageing to a greater extent than males. Additionally, EDL muscles from a separate group of male mice were subjected to eccentric contractions of 15% strain, and larger force deficits were found in aged than in adult mice.

Conclusion: Our findings provide further insight into the muscle atrophy, weakness and fatiguability experienced by the elderly. We have shown that even in the absence of muscle atrophy, there are definite alterations in the physiological properties of whole fast-twitch muscle from ageing mice, and for some of these properties the alterations are more pronounced in female mice than in male mice.

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Fatigue.The time course of force decline during 30 seconds of fatiguing stimulation is shown in (A) for males and (B) for females. It can be seen that in both males and females, EDL muscles from aged animals fatigued less rapidly than muscles from adult animals. At the end of the 30-second fatigue protocol, muscles from aged animals were able to generate a significantly higher percentage of their pre-fatigue force than muscles from adult animals. (Error bars are within thickness of symbols.)
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pone-0012345-g006: Fatigue.The time course of force decline during 30 seconds of fatiguing stimulation is shown in (A) for males and (B) for females. It can be seen that in both males and females, EDL muscles from aged animals fatigued less rapidly than muscles from adult animals. At the end of the 30-second fatigue protocol, muscles from aged animals were able to generate a significantly higher percentage of their pre-fatigue force than muscles from adult animals. (Error bars are within thickness of symbols.)

Mentions: Figure 6 shows the decline in 100-Hz force in EDL muscles during a stimulation protocol consisting of a 1-second, 100-Hz tetanus given every 2 seconds over a period of 30 seconds. In both males (A) and females (B), force declines less rapidly in muscles from aged animals than in muscles from adult animals, indicating a greater fatigue resistance in muscles from aged animals. At the end of the 30-second protocol, muscles of aged animals were able to generate a significantly higher percentage of their pre-fatigue force than muscles of adult animals (males – 54.2±1.3% for aged, 43.8±1.1% for adult, P<0.0001; females – 49.2±1.2% for aged, 43.5±0.7% for adult, P  =  0.0009).


Age- and gender-related changes in contractile properties of non-atrophied EDL muscle.

Chan S, Head SI - PLoS ONE (2010)

Fatigue.The time course of force decline during 30 seconds of fatiguing stimulation is shown in (A) for males and (B) for females. It can be seen that in both males and females, EDL muscles from aged animals fatigued less rapidly than muscles from adult animals. At the end of the 30-second fatigue protocol, muscles from aged animals were able to generate a significantly higher percentage of their pre-fatigue force than muscles from adult animals. (Error bars are within thickness of symbols.)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2925956&req=5

pone-0012345-g006: Fatigue.The time course of force decline during 30 seconds of fatiguing stimulation is shown in (A) for males and (B) for females. It can be seen that in both males and females, EDL muscles from aged animals fatigued less rapidly than muscles from adult animals. At the end of the 30-second fatigue protocol, muscles from aged animals were able to generate a significantly higher percentage of their pre-fatigue force than muscles from adult animals. (Error bars are within thickness of symbols.)
Mentions: Figure 6 shows the decline in 100-Hz force in EDL muscles during a stimulation protocol consisting of a 1-second, 100-Hz tetanus given every 2 seconds over a period of 30 seconds. In both males (A) and females (B), force declines less rapidly in muscles from aged animals than in muscles from adult animals, indicating a greater fatigue resistance in muscles from aged animals. At the end of the 30-second protocol, muscles of aged animals were able to generate a significantly higher percentage of their pre-fatigue force than muscles of adult animals (males – 54.2±1.3% for aged, 43.8±1.1% for adult, P<0.0001; females – 49.2±1.2% for aged, 43.5±0.7% for adult, P  =  0.0009).

Bottom Line: However, it is not entirely clear whether these changes in contractile properties can occur before there is significant atrophy, and whether males and females are affected differently.In the properties of absolute force and muscle relaxation times, females were affected by ageing to a greater extent than males.Our findings provide further insight into the muscle atrophy, weakness and fatiguability experienced by the elderly.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia.

ABSTRACT

Background: In humans, ageing causes skeletal muscles to become atrophied, weak, and easily fatigued. In rodent studies, ageing has been associated with significant muscle atrophy and changes in the contractile properties of the muscles. However, it is not entirely clear whether these changes in contractile properties can occur before there is significant atrophy, and whether males and females are affected differently.

Methods and results: We investigated various contractile properties of whole isolated fast-twitch EDL muscles from adult (2-6 months-old) and aged (12-22 months-old) male and female mice. Atrophy was not present in the aged mice. Compared with adult mice, EDL muscles of aged mice had significantly lower specific force, longer tetanus relaxation times, and lower fatiguability. In the properties of absolute force and muscle relaxation times, females were affected by ageing to a greater extent than males. Additionally, EDL muscles from a separate group of male mice were subjected to eccentric contractions of 15% strain, and larger force deficits were found in aged than in adult mice.

Conclusion: Our findings provide further insight into the muscle atrophy, weakness and fatiguability experienced by the elderly. We have shown that even in the absence of muscle atrophy, there are definite alterations in the physiological properties of whole fast-twitch muscle from ageing mice, and for some of these properties the alterations are more pronounced in female mice than in male mice.

Show MeSH
Related in: MedlinePlus