Limits...
C57BL/6 life span study: age-related declines in muscle power production and contractile velocity.

Graber TG, Kim JH, Grange RW, McLoon LK, Thompson LV - Age (Dordr) (2015)

Bottom Line: We hypothesized and found that power decreased with age not only at P max but also over the load range.Importantly, we found greater age-associated deficits in both power and velocity when the muscles were contracting concentrically against heavy loads (>50 % P 0).The results demonstrate that age-associated difficulty in movement during challenging tasks is likely due, in addition to overall reduced force output, to an accelerated deterioration of power production and contractile velocity under heavily loaded conditions.

View Article: PubMed Central - PubMed

Affiliation: Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota Medical School, Rm 366A Children's Rehab Center, 426 Church Street SE, Minneapolis, MN, 55455, USA, grab0170@umn.edu.

ABSTRACT
Quantification of key outcome measures in animal models of aging is an important step preceding intervention testing. One such measurement, skeletal muscle power generation (force * velocity), is critical for dynamic movement. Prior research focused on maximum power (P max), which occurs around 30-40 % of maximum load. However, movement occurs over the entire load range. Thus, the primary purpose of this study was to determine the effect of age on power generation during concentric contractions in the extensor digitorum longus (EDL) and soleus muscles over the load range from 10 to 90 % of peak isometric tetanic force (P 0). Adult, old, and elderly male C57BL/6 mice were examined for contractile function (6-7 months old, 100 % survival; ~24 months, 75 %; and ~28 months, <50 %, respectively). Mice at other ages (5-32 months) were also tested for regression modeling. We hypothesized and found that power decreased with age not only at P max but also over the load range. Importantly, we found greater age-associated deficits in both power and velocity when the muscles were contracting concentrically against heavy loads (>50 % P 0). The shape of the force-velocity curve also changed with age (a/P 0 increased). In addition, there were prolonged contraction times to maximum force and shifts in the distribution of the myosin light and heavy chain isoforms in the EDL. The results demonstrate that age-associated difficulty in movement during challenging tasks is likely due, in addition to overall reduced force output, to an accelerated deterioration of power production and contractile velocity under heavily loaded conditions.

Show MeSH

Related in: MedlinePlus

EDL contraction time to maximum force increases with age. Equation is a simple linear regression of time to maximum force in seconds with respect to age of the mouse in months. Each symbol represents the contraction time of one mouse
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4401475&req=5

Fig6: EDL contraction time to maximum force increases with age. Equation is a simple linear regression of time to maximum force in seconds with respect to age of the mouse in months. Each symbol represents the contraction time of one mouse

Mentions: In the EDL, the time to reach maximum force (contraction time, measured at 150 Hz, average frequency for P0) was 0.159 ± 0.008, 0.178 ± 0.007, and 0.211 ± 0.010 s in adult, old, and elderly, respectively (Figure 6 shows regression in relation to age). There was no difference in the contraction time between the adult and old muscles, but the elderly had a contraction time 16 % longer than the old (p = 0.036) and 33 % longer than the adult (p < 0.001) (one-way ANOVA, Tukey’s HSD post hoc). Across the life span (5–32 months, n = 63), age had a modest correlation with EDL contraction time (R = 0.525, p < 0.001). In the SOL, there was no significant difference in contraction time (measured at 100 Hz).Fig. 6


C57BL/6 life span study: age-related declines in muscle power production and contractile velocity.

Graber TG, Kim JH, Grange RW, McLoon LK, Thompson LV - Age (Dordr) (2015)

EDL contraction time to maximum force increases with age. Equation is a simple linear regression of time to maximum force in seconds with respect to age of the mouse in months. Each symbol represents the contraction time of one mouse
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401475&req=5

Fig6: EDL contraction time to maximum force increases with age. Equation is a simple linear regression of time to maximum force in seconds with respect to age of the mouse in months. Each symbol represents the contraction time of one mouse
Mentions: In the EDL, the time to reach maximum force (contraction time, measured at 150 Hz, average frequency for P0) was 0.159 ± 0.008, 0.178 ± 0.007, and 0.211 ± 0.010 s in adult, old, and elderly, respectively (Figure 6 shows regression in relation to age). There was no difference in the contraction time between the adult and old muscles, but the elderly had a contraction time 16 % longer than the old (p = 0.036) and 33 % longer than the adult (p < 0.001) (one-way ANOVA, Tukey’s HSD post hoc). Across the life span (5–32 months, n = 63), age had a modest correlation with EDL contraction time (R = 0.525, p < 0.001). In the SOL, there was no significant difference in contraction time (measured at 100 Hz).Fig. 6

Bottom Line: We hypothesized and found that power decreased with age not only at P max but also over the load range.Importantly, we found greater age-associated deficits in both power and velocity when the muscles were contracting concentrically against heavy loads (>50 % P 0).The results demonstrate that age-associated difficulty in movement during challenging tasks is likely due, in addition to overall reduced force output, to an accelerated deterioration of power production and contractile velocity under heavily loaded conditions.

View Article: PubMed Central - PubMed

Affiliation: Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota Medical School, Rm 366A Children's Rehab Center, 426 Church Street SE, Minneapolis, MN, 55455, USA, grab0170@umn.edu.

ABSTRACT
Quantification of key outcome measures in animal models of aging is an important step preceding intervention testing. One such measurement, skeletal muscle power generation (force * velocity), is critical for dynamic movement. Prior research focused on maximum power (P max), which occurs around 30-40 % of maximum load. However, movement occurs over the entire load range. Thus, the primary purpose of this study was to determine the effect of age on power generation during concentric contractions in the extensor digitorum longus (EDL) and soleus muscles over the load range from 10 to 90 % of peak isometric tetanic force (P 0). Adult, old, and elderly male C57BL/6 mice were examined for contractile function (6-7 months old, 100 % survival; ~24 months, 75 %; and ~28 months, <50 %, respectively). Mice at other ages (5-32 months) were also tested for regression modeling. We hypothesized and found that power decreased with age not only at P max but also over the load range. Importantly, we found greater age-associated deficits in both power and velocity when the muscles were contracting concentrically against heavy loads (>50 % P 0). The shape of the force-velocity curve also changed with age (a/P 0 increased). In addition, there were prolonged contraction times to maximum force and shifts in the distribution of the myosin light and heavy chain isoforms in the EDL. The results demonstrate that age-associated difficulty in movement during challenging tasks is likely due, in addition to overall reduced force output, to an accelerated deterioration of power production and contractile velocity under heavily loaded conditions.

Show MeSH
Related in: MedlinePlus