Voluntary strength and muscle characteristics in untrained men and women and male bodybuilders

1987 ◽  
Vol 62 (5) ◽  
pp. 1786-1793 ◽  
Author(s):  
D. G. Sale ◽  
J. D. MacDougall ◽  
S. E. Alway ◽  
J. R. Sutton
Keyword(s):  
Muscle Fiber ◽  
Biceps Brachii ◽  
Peak Torque ◽  
Volume Density ◽  
Isokinetic Dynamometer ◽  
Cross Sectional ◽  
Fiber Area ◽  
Fiber Composition ◽  
Fiber Number ◽  
Voluntary Strength

Eight untrained women (F), 13 untrained men (M), and 11 male bodybuilders (BB) did maximal elbow flexions on an isokinetic dynamometer at velocities of 30, 120, 180, 240, and 300 degrees/s, from which impact torque (IT), peak torque (PT), and work (W) were measured. Biceps and total flexor cross-sectional area (CSA) were measured by computerized tomographic scanning. Muscle fiber area, fiber composition, and collagen volume density were determined from single needle biopsies of biceps brachii. Biceps fiber number was estimated as the ratio of biceps CSA (corrected for connective tissue) to mean fiber area. PT and W decreased at higher velocities in M and BB but not in F; consequently, the correlation between CSA and PT and W was lower at 300 degrees/s (r = 0.58, 0.60) than 30 degrees/s (r = 0.80, 0.79). The ratio of PT to flexor CSA was similar in all groups at 30 degrees/s, whereas F had greater ratios than M and BB at the remaining velocities. F had greater W/CSA ratios than M and BB at all velocities. IT increased at higher velocities in all groups; the increase was greater in F and M than in BB. In contrast to PT and W, the correlation between IT and CSA was greater at 300 degrees/s (r = 0.67) than 30 degrees/s (r = 0.58), and there were no differences among groups in the IT/CSA ratios. Flexor CSA correlated negatively with the ratio of IT, PT, and W to CSA. Muscle fiber composition failed to correlate with any measure of strength. M and BB had greater biceps area, fiber number, and fiber area than F.(ABSTRACT TRUNCATED AT 250 WORDS)

Regionalized adaptations and muscle fiber proliferation in stretch-induced enlargement

1989 ◽  
Vol 66 (2) ◽  
pp. 771-781 ◽  
Author(s):  
S. E. Alway ◽  
P. K. Winchester ◽  
M. E. Davis ◽  
W. J. Gonyea
Keyword(s):  
Muscle Fiber ◽  
Latissimus Dorsi ◽  
Volume Density ◽  
Cross Sectional ◽  
Adult Skeletal Muscle ◽  
Relative Contribution ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Nitric Acid Digestion ◽  
Alpha Type

The relative contribution of increases in fiber area to stretch-induced muscle enlargement was evaluated in the slow tonic fibers of the anterior latissimus dorsi of adult Japanese quails. A weight corresponding to 10% of the bird's body mass was attached to one wing. Thirty days of stretch in 34 birds averaged 171.8 +/- 13.5% increase in muscle mass and 23.5 +/- 0.8% increase in muscle fiber length. The volume density of noncontractile tissue increased in middle and distal regions of stretch-enlarged muscles. Mean fiber cross-sectional area increased 56.7 +/- 12.3% in the midregion of stretched muscles. Further analysis indicated slow beta-fiber hypertrophy occurred in proximal, middle, and distal regions; however, fast alpha-type fiber hypertrophy was limited to middle regions of stretched muscles. Stretched muscles had a significant increase in the frequency of slow beta-fibers that were less than 500 microns 2 in all regions and fast alpha-type fibers in middle and distal regions. Total fiber number was determined after nitric acid digestion of connective tissue in 10 birds. Fiber number increased 51.8 +/- 19.4% in stretched muscle. These results are the first to clearly show that muscle fiber proliferation contributes substantially to adult skeletal muscle stretch-induced enlargement, although we do not know whether the responses of the slow tonic anterior latissimus dorsi might be similar or different from mammalian twitch muscle.

Muscle fiber number in biceps brachii in bodybuilders and control subjects

1984 ◽  
Vol 57 (5) ◽  
pp. 1399-1403 ◽  
Author(s):  
J. D. MacDougall ◽  
D. G. Sale ◽  
S. E. Alway ◽  
J. R. Sutton
Keyword(s):  
Muscle Fiber ◽  
Biceps Brachii ◽  
Cross Sectional Area ◽  
Muscle Size ◽  
Sectional Area ◽  
Cross Sectional ◽  
Trained Subjects ◽  
Fiber Area ◽  
Muscle Cross Sectional Area

Muscle fiber numbers were estimated in vivo in biceps brachii in 5 elite male bodybuilders, 7 intermediate caliber bodybuilders, and 13 age-matched controls. Mean fiber area and collagen volume density were calculated from needle biopsies and muscle cross-sectional area by computerized tomographic scanning. Contralateral measurements in a subsample of seven subjects indicated the method for estimation of fiber numbers to have adequate reliability. There was a wide interindividual range for fiber numbers in biceps (172,085–418,884), but despite large differences in muscle size both bodybuilder groups possessed the same number of muscle fibers as the group of untrained controls. Although there was a high correlation between average cross-sectional fiber area and total muscle cross-sectional area within each group, many of the subjects with the largest muscles also tended to have a large number of fibers. Since there were equally well-trained subjects with fewer than normal fiber numbers, we interpret this finding to be due to genetic endowment rather than to training-induced hyperplasia. The proportion of muscle comprised of connective and other noncontractile tissue was the same for all subjects (approximately 13%), thus indicating greater absolute amounts of connective tissue in the trained subjects. We conclude that in humans, heavy resistance training directed toward achieving maximum size in skeletal muscle does not result in an increase in fiber numbers.

Fiber number, area, and composition of mouse soleus muscle following enlargement

1985 ◽  
Vol 58 (2) ◽  
pp. 619-624 ◽  
Author(s):  
B. F. Timson ◽  
B. K. Bowlin ◽  
G. A. Dudenhoeffer ◽  
J. B. George
Keyword(s):  
Muscle Fiber ◽  
Soleus Muscle ◽  
Histological Section ◽  
Type I ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Male And Female ◽  
Female Mice ◽  
Fiber Area ◽  
Fiber Number

Muscle fiber number, cross-sectional area, and composition were studied in response to enlargement produced by synergistic ablation in the mouse soleus muscle. The effect of the location of a histological section on the number of fibers that appear in the section was also studied using the mouse soleus muscle. Enlargement was produced in the soleus muscle of 15 male and 15 female mice by ablation of the ipsilateral gastrocnemius muscle. Fiber counts, using the nitric acid digestion method, revealed no difference between control and enlarged muscles in male and female mice. Mean fiber area, determined by planimetry, was 49.1 and 34.5% greater following enlargement in male and female mice, respectively. Increase in muscle weight could be totally accounted for by the increase in fiber area following enlargement. A transformation of type II to type I fibers occurred following enlargement for both sexes. Counts of fibers from histological sections revealed that there was a progressive decrease in the fiber number as the section was moved from the belly to the distal end of the muscle. The results of these studies indicate that muscle enlargement in the mouse soleus muscle is due to hypertrophy of the existing muscle fibers.

Contrasts in muscle and myofibers of elite male and female bodybuilders

1989 ◽  
Vol 67 (1) ◽  
pp. 24-31 ◽  
Author(s):  
S. E. Alway ◽  
W. H. Grumbt ◽  
W. J. Gonyea ◽  
J. Stray-Gundersen
Keyword(s):  
Lean Body Mass ◽  
Body Mass ◽  
Biceps Brachii ◽  
Body Height ◽  
Type I ◽  
Type Ii ◽  
Cross Sectional ◽  
Fiber Area ◽  
Fiber Number ◽  
Muscle Cross Sectional Area

Muscle cross-sectional area (CSA), fiber area, and fiber number were determined from the biceps brachii of eight elite male bodybuilders (MB) and five elite female bodybuilders (FB) who had similar training characteristics. Biceps CSA was obtained from computer tomographic scanning and corrected for noncontractile tissue. Biceps CSA was twofold greater in MB relative to FB and strongly correlated to lean body mass (R = 0.93). Biceps CSA expressed per kilogram lean body mass (LBM) or per centimeter body height (BH) was 35% greater in MB compared with FB. Most of the gender difference in muscle CSA was because of greater absolute mean fiber areas in MB (9,607 microns2) relative to FB (5,386 microns2); however, MB also had a significantly greater population of small type II fibers (less than 2,000 microns2) compared with FB. Type II fiber area/LBM averaged 1.6-fold greater in MB compared with FB; however, type I fiber area/LBM was similar between groups. Biceps CSA was positively correlated to fiber CSA (R = 0.75) and fiber number (R = 0.55). This suggests that adaptations to resistance training may be complex and involve fiber hypertrophy and fiber number (e.g., proliferation). Alternatively, since the muscle characteristics before training are not known, these apparent adaptations might be genetically determined attributes.

Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training

1996 ◽  
Vol 81 (5) ◽  
pp. 2004-2012 ◽  
Author(s):  
G. E. McCall ◽  
W. C. Byrnes ◽  
A. Dickinson ◽  
P. M. Pattany ◽  
S. J. Fleck
Keyword(s):  
Resistance Training ◽  
Muscle Fiber ◽  
Biceps Brachii ◽  
College Men ◽  
Capillary Density ◽  
Type I ◽  
Muscle Area ◽  
Cross Sectional ◽  
Fiber Number ◽  
Muscle Groups

McCall, G. E., W. C. Byrnes, A. Dickinson, P. M. Pattany, and S. J. Fleck. Muscle fiber hypertrophy, hyperplasia, and capillary density in college men after resistance training. J. Appl. Physiol. 81(5): 2004–2012, 1996.—Twelve male subjects with recreational resistance training backgrounds completed 12 wk of intensified resistance training (3 sessions/wk; 8 exercises/session; 3 sets/exercise; 10 repetitions maximum/set). All major muscle groups were trained, with four exercises emphasizing the forearm flexors. After training, strength (1-repetition maximum preacher curl) increased by 25% ( P < 0.05). Magnetic resonance imaging scans revealed an increase in the biceps brachii muscle cross-sectional area (CSA) (from 11.8 ± 2.7 to 13.3 ± 2.6 cm2; n = 8; P < 0.05). Muscle biopsies of the biceps brachii revealed increases ( P < 0.05) in fiber areas for type I (from 4,196 ± 859 to 4,617 ± 1,116 μm2; n = 11) and II fibers (from 6,378 ± 1,552 to 7,474 ± 2,017 μm2; n = 11). Fiber number estimated from the above measurements did not change after training (293.2 ± 61.5 × 103 pretraining; 297.5 ± 69.5 × 103 posttraining; n = 8). However, the magnitude of muscle fiber hypertrophy may influence this response because those subjects with less relative muscle fiber hypertrophy, but similar increases in muscle CSA, showed evidence of an increase in fiber number. Capillaries per fiber increased significantly ( P < 0.05) for both type I (from 4.9 ± 0.6 to 5.5 ± 0.7; n = 10) and II fibers (from 5.1 ± 0.8 to 6.2 ± 0.7; n = 10). No changes occurred in capillaries per fiber area or muscle area. In conclusion, resistance training resulted in hypertrophy of the total muscle CSA and fiber areas with no change in estimated fiber number, whereas capillary changes were proportional to muscle fiber growth.

Effects of resistance training on elbow flexors of highly competitive bodybuilders

1992 ◽  
Vol 72 (4) ◽  
pp. 1512-1521 ◽  
Author(s):  
S. E. Alway ◽  
W. H. Grumbt ◽  
J. Stray-Gundersen ◽  
W. J. Gonyea
Keyword(s):  
Resistance Training ◽  
Training Program ◽  
Muscle Mass ◽  
Biceps Brachii ◽  
Fiber Type ◽  
Volume Density ◽  
Elbow Flexors ◽  
Cross Sectional ◽  
Fiber Number ◽  
Muscle Cross Sectional Area

The influence of gender on muscular adaptation of the elbow flexors to 24 wk of heavy resistance training was studied in five male bodybuilders (MB) and five female bodybuilders (FB) who were highly competitive. Muscle cross-sectional area (CSA), fiber area, and fiber number were determined from the biceps brachii, and voluntary elbow flexor torque was obtained at velocities of contraction between 0 and 300 degrees/s. Biceps and flexor CSA was 75.8 and 81% greater, respectively, in MB than in FB, but muscle CSA was not significantly altered by the training program in either group. Because estimated fiber number and the volume density of nonmuscle tissue were similar in MB and FB, most of the gender difference in muscle CSA appeared to be due to greater absolute mean fiber areas in MB (10.51 and 10.68 x 10(3) microns 2 pre- and posttraining, respectively) than in FB (5.33 and 5.96 x 10(3) microns 2 pre- and posttraining, respectively). In neither MB nor FB did fiber type achieve further hypertrophy during the 24-wk training program. These data suggest that the extent of any change in muscle mass or muscle fiber characteristics is minimal after a bodybuilder of either gender has attained a high degree of muscle mass and a highly competitive status.

Estimation of skeletal muscle fiber number by mean fiber dry weight

1984 ◽  
Vol 56 (1) ◽  
pp. 244-247
Author(s):  
B. F. Timson ◽  
G. A. Dudenhoeffer
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Biceps Brachii ◽  
Estimation Method ◽  
Dry Weight ◽  
Skeletal Muscle Fiber ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Nitric Acid Digestion ◽  
Muscle Fiber Number

The purpose of this study was to determine whether skeletal muscle fiber number could be accurately estimated by the determination of mean fiber dry weight (MFD) and total muscle dry weight. The muscles studied were the soleus, plantaris, gastrocnemius, extensor digitorum longus, tibialis anterior, and biceps brachii of the rat, the anterior latissimus dorsi of the chicken, and the flexor carpi radialis of the cat. Bundles of fibers were carefully separated from the muscle following nitric acid digestion (ND) and placed in groups of similar length. MFD determined from 400 to 800 fibers from each group was used to estimate the number of fibers in the remainder of the group. Estimated fiber number was compared with the fiber number determined in the muscle from the contralateral limb by the ND method. No difference in fiber number was observed between the ND method and the MFD estimation method for any of the muscles used in the study. The results indicate that the MFD estimation method is an accurate and relatively rapid method of fiber number determination in skeletal muscle.

Comparison Of Classic Fatigability And Peak Torque Tests Used To Estimate Fast-Twitch Muscle Fiber Composition

2015 ◽  
Vol 47 ◽  
pp. 549-550
Author(s):  
Jose A. Arevalo ◽  
Kathryn A. McLeland ◽  
Lee E. Brown ◽  
Andrew J. Galpin ◽  
Jared W. Coburn
Keyword(s):  
Muscle Fiber ◽  
Peak Torque ◽  
Fiber Composition ◽  
Fast Twitch Muscle ◽  
Fast Twitch

Sprint-training effects on trout (Oncorhynchus mykiss) white muscle structure

1991 ◽  
Vol 69 (11) ◽  
pp. 2786-2790 ◽  
Author(s):  
A. Kurt Gamperl ◽  
E. Don Stevens
Keyword(s):  
Oncorhynchus Mykiss ◽  
Endurance Training ◽  
Muscle Fiber ◽  
White Muscle ◽  
Fiber Type ◽  
Volume Density ◽  
Sprint Training ◽  
Cross Sectional ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Fast Start

In mammals, sprint-type exercise protocols induce muscular adaptation different from that caused by endurance training. Although there are many published studies on endurance training in fish, few have examined sprint (anaerobic) training. This study is an examination of whether sprint-training changes white muscle morphology in addition to its previously shown ability to improve trout fast-start acceleration performance. Rainbow trout (Oncorhynchus mykiss) white muscle was sampled following 4, 8, and 12 weeks of sprint training (30 s duration, every 2nd day). White muscle fiber cross-sectional area and perimeter were unchanged by the sprint-training regimen. The volume density of terminal cisternae, T-tubules, mitochondria, and lipid droplets were also not significantly different following training. A formula relating muscle fiber perimeter and area, derived from trout white muscle, appears to describe accurately the perimeter–area relationship for muscle fibers, regardless of species or fiber type.

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