Strength conditioning in older men: skeletal muscle hypertrophy and improved function

1988 ◽  
Vol 64 (3) ◽  
pp. 1038-1044 ◽  
Author(s):  
W. R. Frontera ◽  
C. N. Meredith ◽  
K. P. O'Reilly ◽  
H. G. Knuttgen ◽  
W. J. Evans
Keyword(s):  
Skeletal Muscle ◽  
Muscle Hypertrophy ◽  
Vastus Lateralis ◽  
Peak Torque ◽  
Older Men ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Skeletal Muscle Function ◽  
Muscle Area ◽  
Fiber Area

The effects of strength conditioning on skeletal muscle function and mass were determined in older men. Twelve healthy untrained volunteers (age range 60-72 yr) participated in a 12-wk strength training program (8 repetitions/set; 3 sets/day; 3 days/wk) at 80% of the one repetition maximum (1 RM) for extensors and flexors of both knee joints. They were evaluated before the program and after 6 and 12 wk of training. Weekly measurements of 1 RM showed a progressive increase in strength in extensors and flexors. By 12 wk extensor and flexor strength had increased 107.4 (P less than 0.0001) and 226.7% (P less than 0.0001), respectively. Isokinetic peak torque of extensors and flexors measured on a Cybex II dynamometer increased 10.0 and 18.5% (P less than 0.05) at 60 degrees/s and 16.7 and 14.7% (P less than 0.05) at 240 degrees/s. The torque-velocity relationship showed an upward displacement of the curve at the end of training, mainly in the slow-velocity high-torque region. Midthigh composition from computerized tomographic scans showed an increase (P less than 0.01) in total thigh area (4.8%), total muscle area (11.4%), and quadriceps area (9.3%). Biopsies of the vastus lateralis muscle revealed similar increases (P less than 0.001) in type I fiber area (33.5%) and type II fiber area (27.6%). Daily excretion of urinary 3-methyl-L-histidine increased with training (P less than 0.05) by an average 40.8%. Strength gains in older men were associated with significant muscle hypertrophy and an increase in myofibrillar protein turnover.

Thermogenesis in human skeletal muscle as measured by direct microcalorimetry and muscle contractile performance during β-adrenoceptor blockade

1986 ◽  
Vol 70 (5) ◽  
pp. 435-441 ◽  
Author(s):  
Birger Fagher ◽  
Hans Liedholm ◽  
Mario Monti ◽  
Ulrich Moritz
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Dynamic Strength ◽  
Peak Torque ◽  
Vastus Lateralis Muscle ◽  
Low Grade ◽  
Double Blind ◽  
Blind Test ◽  
Direct Calorimetry

1. The influence of β-adrenoceptor-blockade on skeletal muscle was studied in ten healthy males with propranolol, atenolol and pindolol randomly given for 8 days each in a cross-over double blind test. After 7 days on each drug, muscle function was tested by an isokinetic dynamometer. Thermogenesis in biopsy samples taken from vastus lateralis muscle after a low grade exercise was studied after 8 days on each drug by direct calorimetry with a perfusion microcalorimeter. 2. Before drug administration, a median heat production rate of 0.67 mW/g of muscle was measured. This value was significantly reduced by 25% during propranolol, but no significant change was found during atenolol or pindolol administration. 3. Peak torque decline during isokinetic endurance test changed significantly in knee flexor but not in extensor muscles, from 15% to 27% after propranolol and from 15% to 23% after pindolol. Maximum dynamic strength was unaltered. 4. Our data suggest that blockade of sympathetic β2-receptors decreases thermogenesis in human skeletal muscle and impairs isokinetic endurance.

scholarly journals Calcium and strontium contractile activation properties of single skinned skeletal muscle fibres from elderly women 66-90 years of age

2021 ◽  
Author(s):  
Sue M Ronaldson ◽  
George D Stephenson ◽  
Stewart I Head
Keyword(s):  
Skeletal Muscle ◽  
Elderly Women ◽  
Vastus Lateralis ◽  
Muscle Fibres ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Lateralis Muscle ◽  
Slow Twitch ◽  
Skeletal Muscle Fibres ◽  
Muscle Biopsies

The single skinned muscle fibre technique was used to investigate Ca2+- and Sr2+- activation properties of skeletal muscle fibres from elderly women (66-90 years). Muscle biopsies were obtained from the vastus lateralis muscle. Three populations of muscle fibres were identified according to their specific Sr2+- activation properties: slow-twitch (type I) fast-twitch (type II) and hybrid (type I/II) fibres. All three fibre types were sampled from the biopsies of 66 to 72 years old women, but the muscle biopsies of women older than 80 years yielded only slow-twitch (type I) fibres. The proportion of hybrid fibres in the vastus lateralis muscle of women of circa 70 years of age (24%) was several-fold greater than in the same muscle of adults (<10%), suggesting that muscle remodelling occurs around this age. There were no differences between the Ca2+- and Sr2+- activation properties of slow-twitch fibres from the two groups of elderly women, but there were differences compared with muscle fibres from adults with respect to sensitivity to Ca2+, steepness of the activation curves, and characteristics of the fibre-type dependent phenomenon of spontaneous force oscillations (SOMO) occurring at sub-maximal levels of activation. The maximal Ca2+ activated specific force from all the fibres collected from the seven old women use in the present study was significantly lower by 20% than in the same muscle of adults. Taken together these results show there are qualitative and quantitative changes in the activation properties of the contractile apparatus of muscle fibres from the vastus lateralis muscle of women with advancing age, and that these changes need to be considered when explaining observed changes in womens mobility with aging.

Do skeletal muscle phenotypic characteristics of Xhosa and Caucasian endurance runners differ when matched for training and racing distances?

2007 ◽  
Vol 103 (3) ◽  
pp. 932-940 ◽  
Author(s):  
Tertius A. Kohn ◽  
Birgitta Essén-Gustavsson ◽  
Kathryn H. Myburgh
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Dry Weight ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Endurance Running ◽  
Exercise Tests ◽  
Black And White ◽  
Endurance Runners

Although East African black athletes dominate endurance running events, it is unknown whether black and white endurance runners with similar racing ability, matched for training, may differ in their skeletal muscle biochemical phenotype. Thirteen Xhosa (XR) and 13 Caucasian (CR) endurance runners were recruited and matched for 10-km performance, average preferred racing distance (PRDA), and training volume. Submaximal and maximal exercise tests were done, and vastus lateralis muscle biopsies were taken. XR were significantly lighter and shorter than CR athletes but had similar maximum oxygen consumption corrected for body weight and peak treadmill speed (PTS). XR had lower plasma lactate concentrations at 80% PTS ( P < 0.05) compared with CR. Also, XR had more type IIA (42.4 ± 9.2 vs. 31.3 ± 11.5%, P < 0.05) and less type I fibers (47.8 ± 10.9 vs. 63.1 ± 13.2%, P < 0.05), although oxidative enzyme activities did not differ. Furthermore, XR compared with CR had higher lactate dehydrogenase (LDH) activity in homogenate muscle samples (383 ± 99 vs. 229 ± 85 μmol·min−1·g dry weight−1, P < 0.05) and in both type IIa ( P < 0.05) and type I ( P = 0.05) single-fiber pools. A marked difference ( P < 0.05) in the composition of LDH isoform content was found between the two groups with XR having higher levels of LDH5-4 isoforms (skeletal muscle isozymes; LDH-M) than CR, which was not accounted for by fiber-type differences alone. These results confirm differences in muscle phenotype and physiological characteristics, particularly associated with high-intensity running.

scholarly journals Microbiopsy Sampling for Examining Age-Related Differences in Skeletal Muscle Fiber Morphology and Composition

2022 ◽  
Vol 12 ◽  
Author(s):  
Garrett M. Hester ◽  
Trisha A. VanDusseldorp ◽  
Phuong L. Ha ◽  
Kaveh Kiani ◽  
Alex A. Olmos ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Vastus Lateralis ◽  
Peak Torque ◽  
Type I ◽  
Type Ii ◽  
Fiber Morphology ◽  
Specific Strength ◽  
Age Related ◽  
Whole Muscle

Introduction: The increasingly popular microbiopsy is an appealing alternative to the more invasive Bergström biopsy given the challenges associated with harvesting skeletal muscle in older populations. Parameters of muscle fiber morphology and composition derived from the microbiopsy have not been compared between young and older adults.Purpose: The purpose of this study was to examine muscle fiber morphology and composition in young (YM) and older (OM) males using the microbiopsy sampling technique. A secondary aim was to determine if specific strength is associated with serum levels of C-terminal agrin fragment [CAF; an indicator of neuromuscular junction (NMJ) degradation].Methods: Thirty healthy, YM (n = 15, age = 20.7 ± 2.2 years) and OM (n = 15, age = 71.6 ± 3.9 years) underwent ultrasound imaging to determine whole-muscle cross-sectional area (CSA) of the vastus lateralis and rectus femoris as well as isometric and isokinetic (60°⋅s–1 and 180°⋅s–1) peak torque testing of the knee extensors. Microbiopsy samples of the vastus lateralis were collected from 13 YM and 11 OM, and immunofluorescence was used to calculate CSA and proportion of type I and type II fibers.Results: Peak torque was lower in OM at all velocities (p ≤ 0.001; d = 1.39–1.86) but only lower at 180°⋅s–1 (p = 0.003; d = 1.23) when normalized to whole-muscle CSA. Whole-muscle CSA was smaller in OM (p = 0.001; d = 1.34), but atrophy was not present at the single fiber level (p &gt; 0.05). Per individual, ∼900 fibers were analyzed, and type I fiber CSA was larger (p = 0.05; d = 0.94) in OM which resulted in a smaller type II/I fiber CSA ratio (p = 0.015; d = 0.95). CAF levels were not sensitive to age (p = 0.159; d = 0.53) nor associated with specific strength or whole-muscle CSA in OM.Conclusion: The microbiopsy appears to be a viable alternative to the Bergström biopsy for histological analyses of skeletal muscle in older adults. NMJ integrity was not influential for age-related differences in specific strength in our healthy, non-sarcopenic older sample.

scholarly journals Cytoskeletal structure of skeletal muscle: identification of an intricate exosarcomeric microtubule lattice in slow- and fast-twitch muscle fibers.

1993 ◽  
Vol 41 (7) ◽  
pp. 1013-1021 ◽  
Author(s):  
S Boudriau ◽  
M Vincent ◽  
C H Côté ◽  
P A Rogers
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Vastus Lateralis ◽  
Muscle Fiber Types ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Mammalian Skeletal Muscle ◽  
Microtubule Network ◽  
Fast Twitch

We used immunochemical quantification and indirect immunofluorescence to investigate the cell content, distribution, and organization of microtubules in adult rat slow-twitch soleus and fast-twitch vastus lateralis muscles. An immunoblotting assay demonstrated that the soleus muscle (primarily Type I fibers) was found to have a 1.7-fold higher relative content of alpha-tubulin compared with the superficial portion of the vastus lateralis muscle (primarily Type IIb fibers). Both physiological muscle types revealed a complex arrangement of microtubules which displayed oblique, longitudinal, and transverse orientations within the sarcoplasmic space. The predominance of any one particular orientation varied significantly from one muscle tissue section to another. Nuclei were completely surrounded by a dense net-like structure of microtubules. Both muscle fiber types were found to possess a higher density of microtubules in the subsarcolemmal region. These microtubules followed the contour of the sarcolemma in slightly contracted fibers and showed a fine punctate appearance indicative of a restricted distribution. The immunofluorescence results indicate that microtubules are associated with the sarcolemma and therefore may form a part of the membrane cytoskeletal domain of the muscle fiber. We conclude that the microtubule network of the adult mammalian skeletal muscle fiber constitutes a bone fide component of the exosarcomeric cytoskeletal lattice domain along with the intermediate filaments, and as such could therefore participate in the mechanical integration of the various organelles of the myofibers during the contraction-relaxation cycle.

Subcellular fractionation reveals HSP72 does not associate with SERCA in human skeletal muscle following damaging eccentric and concentric exercise

2014 ◽  
Vol 116 (11) ◽  
pp. 1503-1511 ◽  
Author(s):  
Noni T. Frankenberg ◽  
Graham D. Lamb ◽  
Kristian Vissing ◽  
Robyn M. Murphy
Keyword(s):  
Skeletal Muscle ◽  
Protein Content ◽  
Human Skeletal Muscle ◽  
Physiological Stress ◽  
Vastus Lateralis ◽  
Tight Binding ◽  
Fold Increase ◽  
Subcellular Fractionation ◽  
Vastus Lateralis Muscle ◽  
Type I

Through its upregulation and/or translocation, heat shock protein 72 (HSP72) is involved in protection and repair of key proteins after physiological stress. In human skeletal muscle we investigated HSP72 protein after eccentric (ECC1) and concentric (CONC) exercise and repeated eccentric exercise (ECC2; 8 wk later) and whether it translocated from its normal cytosolic location to membranes/myofibrils. HSP72 protein increased ∼2-fold 24 h after ECC1, with no apparent change after CONC or ECC2. In resting (nonstressed) human skeletal muscle the total pool of HSP72 protein was present almost exclusively in the cytosolic fraction, and after each exercise protocol the distribution of HSP72 protein remained unaltered. Overall, the amount of HSP72 protein in the cytosol increased 24 h after ECC1, matching the fold increase that was measured in total HSP72 protein. To better ascertain the capabilities and limitations of HSP72, using quantitative Western blotting we determined the HSP72 protein content to be 11.4 μmol/kg wet weight in resting human vastus lateralis muscle, which is comprised of Type I (slow-twitch) and Type II (fast-twitch) fibers. HSP72 protein content was similar in individual Type I or II fiber segments. After physiological stress, HSP72 content can increase and, although the functional consequences of increased amounts of HSP72 protein are poorly understood, it has been shown to bind to and protect protein pumps like SERCA and Na+-K+-ATPase. Given no translocation of cytosolic HSP72, these findings suggest eccentric contractions, unlike other forms of stress such as heat, do not trigger tight binding of HSP72 to its primary membrane-bound target proteins, in particular SERCA.

Operation Everest II: adaptations in human skeletal muscle

1989 ◽  
Vol 66 (5) ◽  
pp. 2454-2461 ◽  
Author(s):  
H. J. Green ◽  
J. R. Sutton ◽  
A. Cymerman ◽  
P. M. Young ◽  
C. S. Houston
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Succinic Dehydrogenase ◽  
High Energy ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Type Ii ◽  
Cross Sectional ◽  
Distribution Type

Adaptations in skeletal muscle in response to progressive hypobaria were investigated in eight male subjects [maximal O2 uptake = 51.2 +/- 3.0 (SE) ml.kg-1.min-1] over 40 days of progressive decompression to the stimulated altitude of the summit of Mt. Everest. Samples of the vastus lateralis muscle extracted before decompression (SL-1), at 380 and 282 Torr, and on return to sea level (SL-2) indicated that maximal activities of enzymes representative of the citric acid cycle, beta-oxidation, glycogenolysis, glycolysis, glucose phosphorylation, and high-energy phosphate transfer were unchanged (P greater than 0.05) at 380 and 282 Torr over initial SL-1 values. After exposure to 282 Torr, however, representing an additional period of approximately 7 days, reductions (P less than 0.05) were noted in succinic dehydrogenase (21%), citrate synthetase (37%), and hexokinase (53%) between SL-2 and 380 Torr. No changes were found in the other enzymes. Capillarization as measured by the number of capillaries per cross-sectional area (CC/FA) was increased (P less than 0.05) in both type I (0.94 +/- 0.8 vs. 1.16 +/- 0.05) and type II (0.84 +/- 0.07 vs. 1.05 +/- 0.08) fibers between SL-1 and SL-2. This increase was mediated by a reduction in fiber area. No changes were found in fiber-type distribution (type I vs. type II). These findings do not support the hypothesis, at least in humans, that, at the level of the muscle cell, extreme hypobaric hypoxia elicits adaptations directed toward maximizing oxidative function.

Single-fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+-K+-ATPase α- and β-isoforms in human skeletal muscle

2015 ◽  
Vol 118 (6) ◽  
pp. 699-706 ◽  
Author(s):  
V. L. Wyckelsma ◽  
M. J. McKenna ◽  
F. R. Serpiello ◽  
C. R. Lamboley ◽  
R. J. Aughey ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Western Blotting ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Single Fiber ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Functional Roles

The Na+-K+-ATPase (NKA) plays a key role in muscle excitability, but little is known in human skeletal muscle about fiber-type-specific differences in NKA isoform expression or adaptability. A vastus lateralis muscle biopsy was taken in 17 healthy young adults to contrast NKA isoform protein relative abundance between type I and IIa fibers. We further investigated muscle fiber-type-specific NKA adaptability in eight of these adults following 4-wk repeated-sprint exercise (RSE) training, comprising three sets of 5 × 4-s sprints, 3 days/wk. Single fibers were separated, and myosin heavy chain (I and IIa) and NKA (α1–3 and β1–3) isoform abundance were determined via Western blotting. All six NKA isoforms were expressed in both type I and IIa fibers. No differences between fiber types were found for α1-, α2-, α3-, β1-, or β3-isoform abundances. The NKA β2-isoform was 27% more abundant in type IIa than type I fibers ( P < 0.05), with no other fiber-type-specific trends evident. RSE training increased β1 in type IIa fibers (pretraining 0.70 ± 0.25, posttraining 0.84 ± 0.24 arbitrary units, 42%, P < 0.05). No training effects were found for other NKA isoforms. Thus human skeletal muscle expresses all six NKA isoforms and not in a fiber-type-specific manner; this points to their different functional roles in skeletal muscle cells. Detection of elevated NKA β1 after RSE training demonstrates the sensitivity of the single-fiber Western blotting technique for fiber-type-specific intervention effects.

Lower limb skeletal muscle function after 6 wk of bed rest

1997 ◽  
Vol 82 (1) ◽  
pp. 182-188 ◽  
Author(s):  
H. E. Berg ◽  
L. Larsson ◽  
P. A. Tesch
Keyword(s):  
Skeletal Muscle ◽  
Lower Limb ◽  
Muscle Function ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Bed Rest ◽  
Emg Activity ◽  
Type I ◽  
Skeletal Muscle Function

Berg, H. E., L. Larsson, and P. A. Tesch. Lower limb skeletal muscle function after 6 wk of bed rest. J. Appl. Physiol. 82(1): 182–188, 1997.—Force, electromyographic (EMG) activity, muscle mass, and fiber characteristics were studied in seven healthy men before and after 6 wk of bed rest. Maximum voluntary isometric and concentric knee extensor torque decreased ( P < 0.05) uniformly across angular velocities by 25–30% after bed rest. Maximum quadricep rectified EMG decreased by 19 ± 23%, whereas submaximum (100-Nm isometric action) EMG increased by 44 ± 28%. Knee extensor muscle cross-sectional area (CSA), assessed by using magnetic resonance imaging, decreased by 14 ± 4%. Maximum torque per knee extensor CSA decreased by 13 ± 9%. Vastus lateralis fiber CSA decreased 18 ± 14%. Neither type I, IIA, and IIB fiber percentages nor their relative proportions of myosin heavy chain (MHC) isoforms were altered after bed rest. Because the decline in strength could not be entirely accounted for by decreased muscle CSA, it is suggested that the strength loss is also due to factors resulting in decreased neural input to muscle and/or reduced specific tension of muscle, as evidenced by a decreased torque/EMG ratio. Additionally, it is concluded that muscle unloading in humans does not induce important changes in fiber type or MHC composition or in vivo muscle contractile properties.

scholarly journals Associations of Serum Adiponectin with Skeletal Muscle Morphology and Insulin Sensitivity

2009 ◽  
Vol 94 (3) ◽  
pp. 953-957 ◽  
Author(s):  
Erik Ingelsson ◽  
Johan Ärnlöv ◽  
Björn Zethelius ◽  
Ramachandran S. Vasan ◽  
Allan Flyvbjerg ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Confidence Interval ◽  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Capillary Density ◽  
Serum Adiponectin ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Muscle Morphology

Abstract Context: Skeletal muscle morphology and function are strongly associated with insulin sensitivity. Objective: The objective of the study was to test the hypothesis that circulating adiponectin is associated with skeletal muscle morphology and that adiponectin mediates the relation of muscle morphology to insulin sensitivity. Design, Settings, and Participants: This was a cross-sectional investigation of 461 men aged 71 yr, participants of the community-based Uppsala Longitudinal Study of Adult Men study. Main Outcome Measures: Measures included serum adiponectin, insulin sensitivity measured with euglycemic insulin clamp technique, and capillary density and muscle fiber composition determined from vastus lateralis muscle biopsies. Results: In multivariable linear regression models (adjusting for age, physical activity, fasting glucose, and pharmacological treatment for diabetes), serum adiponectin levels rose with increasing capillary density (β, 0.30 per 50 capillaries per square millimeter increase; P = 0.041) and higher proportion of type I muscle fibers (β, 0.27 per 10% increase; P = 0.036) but declined with a higher proportion of type IIb fibers (β, −0.39 per 10% increase; P = 0.014). Using bootstrap methods to examine the potential role of adiponectin in associations between muscle morphology and insulin sensitivity and the associations of capillary density (β difference, 0.041; 95% confidence interval 0.001, 0.085) and proportion of type IIb muscle fibers (β difference, −0.053; 95% confidence interval −0.107, −0.002) with insulin sensitivity were significantly attenuated when adiponectin was included in the models. Conclusions: Circulating adiponectin concentrations were higher with increasing skeletal muscle capillary density and in individuals with higher proportion of slow oxidative muscle fibers. Furthermore, our results indicate that adiponectin could be a partial mediator of the relations between skeletal muscle morphology and insulin sensitivity.

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