scholarly journals Differential effects of mild therapeutic exercise during a period of inactivity on power generation in soleus type I single fibers with age

2012 ◽  
Vol 112 (10) ◽  
pp. 1752-1761 ◽  
Author(s):  
Jong-Hee Kim ◽  
LaDora V. Thompson
Keyword(s):  
Young Adult ◽  
Peak Power ◽  
Fiber Diameter ◽  
Weight Bearing ◽  
Age Groups ◽  
Exercise Program ◽  
Type I ◽  
Therapeutic Exercise ◽  
Middle Aged ◽  
Single Fibers

The purpose of this study was to investigate the effects of mild therapeutic exercise (treadmill) in preventing the inactivity-induced alterations in contractile properties (e.g., power, force, and velocity) of type I soleus single fibers in three different age groups. Young adult (5- to 12-mo-old), middle-aged (24- to 31-mo-old), and old (32- to 40-mo-old) F344BNF1 rats were randomly assigned to three experimental groups: weight-bearing control (CON), non-weight bearing (NWB), and NWB with exercise (NWBX). NWB rats were hindlimb suspended for 2 wk, representing inactivity. The NWBX rats were hindlimb suspended for 2 wk and received therapeutic exercise on a treadmill four times a day for 15 min each. Peak power and isometric maximal force were reduced following hindlimb suspension (HS) in all three age groups. HS decreased fiber diameter in young adult and old rats (−21 and −12%, respectively). Specific tension (isometric maximal force/cross-sectional area) was significantly reduced in both the middle-aged (−36%) and old (−23%) rats. The effects of the mild therapeutic exercise program on fiber diameter and contractile properties were age specific. Mild treadmill therapeutic exercise attenuated the HS-induced reduction in fiber diameter (+17%, 93% level of CON group) and peak power (μN·fiber length·s−1) (+46%, 63% level of CON group) in young adult rats. In the middle-aged animals, this exercise protocol improved peak power (+60%, 100% level of CON group) and normalized power (kN·m−2·fiber length·s−1) (+45%, 108% level of CON group). Interestingly, treadmill exercise resulted in a further reduction in shortening velocity (−42%, 67% level of CON group) and specific tension (−29%, 55% level of CON group) in the old animals. These results suggest that mild treadmill exercise is beneficial in attenuating and preventing inactivity-induced decline in peak power of type I soleus single fibers in young adult and middle-aged animals, respectively. However, this exercise program does not prevent the HS-induced decline in muscle function in the old animals.

scholarly journals Inactivity, age, and exercise: single-muscle fiber power generation

2013 ◽  
Vol 114 (1) ◽  
pp. 90-98 ◽  
Author(s):  
Jong-Hee Kim ◽  
LaDora V. Thompson
Keyword(s):  
Young Adult ◽  
Peak Power ◽  
Weight Bearing ◽  
Type I ◽  
Type Ii ◽  
Middle Aged ◽  
Adult Rats ◽  
Maximal Force ◽  
Old Rats ◽  
Type I Fibers

We examined the effects of mild therapeutic exercise during a period of inactivity on size and contractile functions of myosin heavy chain (MHC) type I ( n = 204) and type II ( n = 419) single fibers from the medial gastrocnemius in three age groups. Young adult (5–12 mo), middle-aged (24–31 mo), and old (32–37 mo) F344BNF1 rats were assigned to one of three groups: weight-bearing control, non-weight bearing (NWB), and NWB plus exercise (NWBX). Fourteen days of hindlimb suspension were applied in NWB rats. The NWBX rats exercised on the treadmill for 15 min, four times a day, during the period of NWB. The NWBX did not improve peak power, but increased normalized power of MHC type I fibers in young adult rats. In MHC type II fibers, NWBX did not change peak power, isometric maximal force, Vmax, and fiber size from young adult and middle-aged rats. NWBX did not improve peak power and isometric maximal force and showed a dramatic decline in Vmax and normalized power in the old rats. Collectively, mild treadmill exercise during a period of inactivity does not improve peak power of MHC type I or type II fiber from the gastrocnemius in young, middle-aged, and old rats. However, NWBX is beneficial in enhancing normalized power of MHC type I fibers in young adult rats, most likely due to the stimulus intensity and the ability of the individual fibers to adapt to the stimulus. In contrast, several factors, such as impaired adaptation potential, inappropriate exercise intensity, or increased susceptibility to muscle damage, may contribute to the lack of improvement in the older rats.

scholarly journals Peak force and maximal shortening velocity of soleus fibers after non-weight-bearing and resistance exercise

1997 ◽  
Vol 82 (1) ◽  
pp. 189-195 ◽  
Author(s):  
Jeffrey J. Widrick ◽  
Robert H. Fitts
Keyword(s):  
Resistance Exercise ◽  
Elevated Level ◽  
Fiber Diameter ◽  
Weight Bearing ◽  
Normal Weight ◽  
Peak Force ◽  
Type I ◽  
Shortening Velocity ◽  
Adult Rats ◽  
Cross Sectional

Widrick, Jeffrey J., and Robert H. Fitts. Peak force and maximal shortening velocity of soleus fibers after non-weight-bearing and resistance exercise. J. Appl. Physiol. 82(1): 189–195, 1997.—This study examined the effectiveness of resistance exercise as a countermeasure to non-weight-bearing-induced alterations in the absolute peak force, normalized peak force (force/fiber cross-sectional area), peak stiffness, and maximal shortening velocity ( V o) of single permeabilized type I soleus muscle fibers. Adult rats were subjected to one of the following treatments: normal weight bearing (WB), non-weight bearing (NWB), or NWB with exercise treatments (NWB+Ex). The hindlimbs of the NWB and NWB+Ex rats were suspended for 14 days via tail harnesses. Four times each day, the NWB+Ex rats were removed from suspension and performed 10 climbs (∼15 cm each) up a steep grid with a 500-g mass (∼1.5 times body mass) attached to their tail harness. NWB was associated with significant reductions in type I fiber diameter, absolute force, normalized force, and stiffness. Exercise treatments during NWB attenuated the decline in fiber diameter and absolute force by almost 60% while maintaining normalized force and stiffness at WB levels. Type I fiber V oincreased by 33% with NWB and remained at this elevated level despite the exercise treatments. We conclude that in comparison to intermittent weight bearing only (J. J. Widrick, J. J. Bangart, M. Karhanek, and R. H. Fitts. J. Appl. Physiol. 80: 981–987, 1996), resistance exercise was more effective in attenuating alterations in type I soleus fiber absolute force, normalized force, and stiffness but was less effective in restoring type I fiber V oto WB levels.

Effect of aging on tracheal mucociliary clearance in beagle dogs

1987 ◽  
Vol 62 (3) ◽  
pp. 1331-1334 ◽  
Author(s):  
S. L. Whaley ◽  
B. A. Muggenburg ◽  
F. A. Seiler ◽  
R. K. Wolff
Keyword(s):  
Young Adult ◽  
Gamma Camera ◽  
Mucociliary Clearance ◽  
Age Groups ◽  
Beagle Dogs ◽  
Velocity Measurements ◽  
Middle Aged ◽  
Age Related ◽  
Age Related Changes ◽  
Made In

Tracheal mucous velocity measurements were made in 24 beagle dogs in five age groups, using a gamma camera to detect movement of instilled 99mTc-macroaggregated albumin. Age groups were defined as immature (9–10 mo), young adult (2.8–3.0 yr), middle aged (6.7–6.9 yr), mature (9.6–9.8 yr), and aged dogs (13.6–16.2 yr). Mean velocities were 3.6 +/- 0.4 (SE) mm/min in the immature dogs, 9.7 +/- 0.6 mm/min in the young adults, 6.9 +/- 0.5 mm/min in the middle-aged dogs, 3.5 +/- 0.8 mm/min in the mature dogs, and 2.9 +/- 0.5 mm/min in the aged dogs. Tracheal mucous velocity was significantly (P less than 0.05) greater in the young adult and middle-aged groups compared with the immature, mature, and aged dogs. This pattern of age-related changes was noted to be similar to age-related changes described for certain pulmonary function measurements.

scholarly journals Force-velocity-power and force-pCa relationships of human soleus fibers after 17 days of bed rest

1998 ◽  
Vol 85 (5) ◽  
pp. 1949-1956 ◽  
Author(s):  
J. J. Widrick ◽  
K. M. Norenberg ◽  
J. G. Romatowski ◽  
C. A. Blaser ◽  
M. Karhanek ◽  
...  
Keyword(s):  
Peak Power ◽  
Weight Bearing ◽  
Bed Rest ◽  
Force Transducer ◽  
Hindlimb Suspension ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Adult Men ◽  
Force Velocity

Soleus muscle fibers from the rat display a reduction in peak power and Ca2+ sensitivity after hindlimb suspension. To examine human responses to non-weight bearing, we obtained soleus biopsies from eight adult men before and immediately after 17 days of bed rest (BR). Single chemically skinned fibers were mounted between a force transducer and a servo-controlled position motor and activated with maximal (isotonic properties) and/or submaximal (Ca2+ sensitivity) levels of free Ca2+. Gel electrophoresis indicated that all pre- and post-BR fibers expressed type I myosin heavy chain. Post-BR fibers obtained from one subject displayed increases in peak power and Ca2+ sensitivity. In contrast, post-BR fibers obtained from the seven remaining subjects showed an average 11% reduction in peak power ( P < 0.05), with each individual displaying a 7–27% reduction in this variable. Post-BR fibers from these subjects were smaller in diameter and produced 21% less force at the shortening velocity associated with peak power. However, the shortening velocity at peak power output was elevated 13% in the post-BR fibers, which partially compensated for their lower force. Post-BR fibers from these same seven subjects also displayed a reduced sensitivity to free Ca2+( P < 0.05). These results indicate that the reduced functional capacity of human lower limb extensor muscles after BR may be in part caused by alterations in the cross-bridge mechanisms of contraction.

scholarly journals Effect of intermittent weight bearing on soleus fiber force-velocity-power and force-pCa relationships

1997 ◽  
Vol 82 (6) ◽  
pp. 1905-1910 ◽  
Author(s):  
J. J. Bangart ◽  
J. J. Widrick ◽  
R. H. Fitts
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Weight Bearing ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Functional Changes ◽  
Maximal Activation ◽  
Force Velocity ◽  
Type I Fibers

Bangart, J. J., J. J. Widrick, and R. H. Fitts. Effect of intermittent weight bearing on soleus fiber force-velocity-power and force-pCa relationships. J. Appl. Physiol. 82(6): 1905–1910, 1997.—Rat permeabilized type I soleus fibers displayed a 33% reduction in peak power output and a 36% increase in the free Ca2+ concentration required for one-half maximal activation after 14 days of hindlimb non-weight bearing (NWB). We examined the effectiveness of intermittent weight bearing (IWB; consisting of four 10-min periods of weight bearing/day) as a countermeasure to these functional changes. At peak power output, type I fibers from NWB animals produced 54% less force and shortened at a 56% greater velocity than did type I fibers from control weight-bearing animals while type I fibers from the IWB rats produced 26% more absolute force than did fibers from the NWB group and shortened at a velocity that was only 80% of the NWB group mean. As a result, no difference was observed in the average peak power of fibers from the IWB and NWB animals. Hill plot analysis of force-pCa relationships indicated that fibers from the IWB group required similar levels of free Ca2+ to reach half-maximal activation in comparison to fibers from the weight-bearing group. However, at forces <50% of peak force, the force-pCa curve for fibers from the IWB animals clearly fell between the relationships observed for the other two groups. In summary, IWB treatments 1) attenuated the NWB-induced reduction in fiber Ca2+sensitivity but 2) failed to prevent the decline in peak power that occurs during NWB because of opposing effects on fiber force (an increase vs. NWB) and shortening velocity (a decrease vs. NWB).

Reduced Efficacy of Volatile Anesthetic Preconditioning with Advanced Age in Isolated Rat Myocardium

2004 ◽  
Vol 100 (3) ◽  
pp. 589-597 ◽  
Author(s):  
Roman Sniecinski ◽  
Hong Liu
Keyword(s):  
Young Adult ◽  
Ischemic Preconditioning ◽  
Age Groups ◽  
Left Ventricular ◽  
Aged Rats ◽  
Middle Aged ◽  
Beneficial Effects ◽  
Anesthetic Preconditioning ◽  
Intracellular Ca ◽  
Developed Pressure

Background Ischemic preconditioning and anesthetic preconditioning (APC) are reported to decrease myocardial infarct size during ischemia-reperfusion injury. However, the beneficial effects of ischemic preconditioning have been shown to decrease with advancing age. Although the mechanisms of ischemic preconditioning and APC are thought to be similar, it is not known whether the beneficial effects of APC are also reduced in the aged myocardium. Methods Male Fischer 344 rats of three age groups (2-4, 10-12, and 20-24 months) were used. Hearts were Langendorff perfused. Six hearts in each age group were pretreated with 10 min of sevoflurane and a 5-min washout before 25 min of ischemia and 60 min of reperfusion. Six control hearts in each age group received no treatment before ischemia. Nuclear magnetic resonance was used to measure intracellular Na, intracellular Ca, and intracellular pH, respectively. Left ventricular developed pressure, creatine kinase, and infarct size were measured. Results Ischemia decreases intracellular pH and increases intracellular Na and intracellular Ca in all age groups. APC blunts the pH decreases in young adult and middle-aged rats, but not in aged rats. APC decreased intracellular Na and intracellular Ca accumulation during ischemia in young adult and middle-aged hearts. APC improved adenosine triphosphate recovery in young rats but not in aged rats. Creatine kinase and infarct sizes were significantly reduced and left ventricular developed pressure was improved with APC in the young adult and middle-aged groups but not the aged group. Conclusions The benefits of APC are significantly reduced with advanced age in an isolated rat heart model.

scholarly journals Factors Associated with Successful Smoking Cessation According to Age Group: Findings of an 11-Year Korea National Survey

2021 ◽  
Vol 18 (4) ◽  
pp. 1576
Author(s):  
Youngmee Kim ◽  
Ji Sung Lee ◽  
Won-Kyung Cho
Keyword(s):  
Smoking Cessation ◽  
Young Adult ◽  
Age Groups ◽  
Middle Aged ◽  
Factors Affecting ◽  
Factors Associated ◽  
Health And Nutrition ◽  
Korean Adult ◽  
Using Data ◽  
Policies And Programs

Previous studies suggest that factors related to smoking cessation may vary with age. This study examined the factors affecting smoking cessation by age among Korean adult male smokers using data from the Korea National Health and Nutrition Examination Survey from 2007 to 2018 (excluding 2013). Logistic regression analyses were used to investigate various factors associated with smoking cessation in three different age groups. Out of a total of 15,492 individuals, 31.5% of the 3523 individuals aged 19–39 years (young adult), 54.7% of the 7390 individuals aged 40–64 years (middle-aged), and 78.6% of the 4589 individuals aged ≥65 years (older adults) succeeded in quitting. In the young adult and middle-aged groups, being married was associated with successful quitting, and lifetime smoking was associated with unsuccessful quitting. Willpower and several comorbidities were related to successful cessation in the middle-aged and older adult groups. Skipping any meal, which suggests unhealthy behavior, was negatively related to quitting in the young adult group. We observed that factors associated with smoking cessation success or failure differed by age, which should be considered when developing smoking cessation policies and programs.

scholarly journals Spaceflight effects on single skeletal muscle fiber function in the rhesus monkey

2000 ◽  
Vol 279 (5) ◽  
pp. R1546-R1557 ◽  
Author(s):  
Robert H. Fitts ◽  
Dominique Desplanches ◽  
Janell G. Romatowski ◽  
Jeffrey J. Widrick
Keyword(s):  
Rhesus Monkey ◽  
Peak Power ◽  
Fiber Diameter ◽  
Fiber Type ◽  
Peak Force ◽  
Medial Gastrocnemius ◽  
Type I ◽  
Type Ii ◽  
Fast Twitch ◽  
Type Ii Fibers

The purpose of this investigation was to understand how 14 days of weightlessness alters the cellular properties of individual slow- and fast-twitch muscle fibers in the rhesus monkey. The diameter of the soleus (Sol) type I, medial gastrocnemius (MG) type I, and MG type II fibers from the vivarium controls averaged 60 ± 1, 46 ± 2, and 59 ± 2 μm, respectively. Both a control 1-G capsule sit (CS) and spaceflight (SF) significantly reduced the Sol type I fiber diameter (20 and 13%, respectively) and peak force, with the latter declining from 0.48 ± 0.01 to 0.31 ± 0.02 (CS group) and 0.32 ± 0.01 mN (SF group). When the peak force was expressed as kiloNewtons per square meter (kN/m2), only the SF group showed a significant decline. This group also showed a significant 15% drop in peak fiber stiffness that suggests that fewer cross bridges were contracting in parallel. In the MG, SF but not CS depressed the type I fiber diameter and force. Additionally, SF significantly depressed absolute (mN) and relative (kN/m2) force in the fast-twitch MG fibers by 30% and 28%, respectively. The Ca2+ sensitivity of the type I fiber (Sol and MG) was significantly reduced by growth but unaltered by SF. Flight had no significant effect on the mean maximal fiber shortening velocity in any fiber type or muscle. The post-SF Sol type I fibers showed a reduced peak power and, at peak power, an elevated velocity and decreased force. In conclusion, CS and SF caused atrophy and a reduced force and power in the Sol type I fiber. However, only SF elicited atrophy and reduced force (mN) in the MG type I fiber and a decline in relative force (kN/m2) in the Sol type I and MG type II fibers.

Consumption of Greek yogurt during 12 weeks of high-impact loading exercise increases bone formation in young, adult males – a secondary analysis from a randomized trial

2020 ◽  
Vol 45 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Aaron D. Bridge ◽  
Joseph Brown ◽  
Hayden Snider ◽  
Wendy E. Ward ◽  
Brian D. Roy ◽  
...  
Keyword(s):  
Young Adult ◽  
Bone Formation ◽  
Bone Turnover ◽  
G Protein ◽  
Exercise Program ◽  
High Impact ◽  
Type I ◽  
Adult Males ◽  
Young Adult Males ◽  
Over Time

Exercise combined with protein and calcium has been shown to benefit bone turnover and bone metabolism. Greek yogurt (GY) contains important nutrients that support bone but has yet to be studied with exercise for this purpose. Thirty untrained, university-aged, males were randomized to 2 groups (n = 15/group): GY (20 g protein, 208 mg calcium/dose) or placebo pudding (PP; 0 g protein, 0 g calcium/dose) consumed 3×/day on training days and 2×/day on nontraining days. Both groups underwent a resistance/plyometric training program for 12 weeks. Blood was obtained at weeks 0, 1, and 12 to measure procollagen-type-I-N-terminal-propeptide (P1NP) and C-terminal-telopeptide (CTX). After outlier treatment, P1NP increased more over time in GY versus PP (p = 0.002; interaction). Both groups decreased CTX over time (p = 0.046; time effect). Following 1 week of training, there was a trend towards a significant increase in CTX in PP with no change in GY (p = 0.062; interaction). P1NP changed more in GY than PP (baseline to week 12; p = 0.029) as did the P1NP/CTX ratio (p = 0.015) indicating a greater increase in formation with GY. Thus, GY added to a high-load, high-impact exercise program positively shifted bone turnover towards increased formation while attenuating resorption. GY could be a plausible postexercise food to support bone health in young adult males. Novelty Greek yogurt, with exercise, increased bone formation in young adult males over 12 weeks. After 1 week of an osteogenic exercise program, Greek yogurt tended to blunt a rise in bone resorption seen with the placebo. Greek yogurt is a plausible postexercise food that supports bone.

scholarly journals Age-dependent pathogenic characteristics of SARS-CoV-2 infection in ferrets

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Young-Il Kim ◽  
Kwang-Min Yu ◽  
June-Young Koh ◽  
Eun-Ha Kim ◽  
Se-Mi Kim ◽  
...  
Keyword(s):  
Young Adult ◽  
Direct Contact ◽  
Clinical Symptoms ◽  
Age Groups ◽  
Type I ◽  
Activated T Cells ◽  
Virus Shedding ◽  
Viral Loads ◽  
Gene Sets ◽  
M1 Macrophage

AbstractWhile the seroprevalence of SARS-CoV-2 in healthy people does not differ significantly among age groups, those aged 65 years or older exhibit strikingly higher COVID-19 mortality compared to younger individuals. To further understand differing COVID-19 manifestations in patients of different ages, three age groups of ferrets are infected with SARS-CoV-2. Although SARS-CoV-2 is isolated from all ferrets regardless of age, aged ferrets (≥3 years old) show higher viral loads, longer nasal virus shedding, and more severe lung inflammatory cell infiltration, and clinical symptoms compared to juvenile (≤6 months) and young adult (1–2 years) groups. Furthermore, direct contact ferrets co-housed with the virus-infected aged group shed more virus than direct-contact ferrets co-housed with virus-infected juvenile or young adult ferrets. Transcriptome analysis of aged ferret lungs reveals strong enrichment of gene sets related to type I interferon, activated T cells, and M1 macrophage responses, mimicking the gene expression profile of severe COVID-19 patients. Thus, SARS-CoV-2-infected aged ferrets highly recapitulate COVID-19 patients with severe symptoms and are useful for understanding age-associated infection, transmission, and pathogenesis of SARS-CoV-2.

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