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.

Fiber number and size in overloaded chicken anterior latissimus dorsi muscle

1983 ◽  
Vol 54 (5) ◽  
pp. 1292-1297 ◽  
Author(s):  
P. D. Gollnick ◽  
D. Parsons ◽  
M. Riedy ◽  
R. L. Moore
Keyword(s):  
Latissimus Dorsi ◽  
Histochemical Staining ◽  
Type I ◽  
Fiber Volume ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Relative Contribution ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Muscle Fiber Number

The relative contribution of increases in fiber area and number was evaluated in the chicken anterior latissimus dorsi (ALD) muscle in which enlargement was induced by hanging a weight on one wing. ALD muscles from wings to which weights had been attached for periods ranging from 6 to 65 days weighed an average of 105% (range 22–225%) more than control muscles. Total muscle fiber number, determined by direct counts after nitric acid digestion and fiber dissection, and the frequency of branched fibers were unchanged by muscular enlargement. Fiber cross-sectional area was greater (P less than 0.01) in the enlarged muscles. A close relationship existed (r = 0.78) between actual muscle weight and weight calculated as the product of fiber volume, total fiber number, and muscle density for the control and enlarged muscles. Histochemical staining revealed a conversion of type IIa to type I fibers in the stretched muscles. These results support the concept that skeletal muscle enlargement in response to chronic overload is produced by hypertrophy of preexisting fibers and not be a formation of new fibers.

Role of muscle fiber hypertrophy and hyperplasia in intermittently stretched avian muscle

1993 ◽  
Vol 74 (4) ◽  
pp. 1893-1898 ◽  
Author(s):  
J. Antonio ◽  
W. J. Gonyea
Keyword(s):  
Muscle Fiber ◽  
Latissimus Dorsi ◽  
Histological Section ◽  
Volume Density ◽  
Left Wing ◽  
Avian Muscle ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Equivalent Load ◽  
The Right

In the chronic stretch model, muscle fiber hyperplasia precedes fiber hypertrophy [Alway et al. Am. J. Physiol. 259 (Cell Physiol. 28): C92-C102, 1990]. This study was undertaken to determine if an intermittent stretch protocol would induce fiber hypertrophy without fiber hyperplasia. A weight equalt to 10% of the bird's mass was attached to the right wing of seven adult quail while the left wing served as the intra-animal control. The weight was attached to the wing for 24-h periods interspersed with a 48- to 72-hr rest interval. The actual stretch time was 5 days while the length of the treatment period was 15 days. Muscle mass and length increased significantly 53.1 +/- 9.0 and 26.1 +/- 7.3% in the stretched anterior latissimus dorsi. Fiber number, which was determined from a histological section in the midregion of the muscle, did not change (control 1,651.6 +/- 94.8; stretch 1,626.0 +/- 70.9). The slow tonic fiber areas increased significantly an average of 28.6 +/- 5.7%, whereas the fast fibers increased 18.5 +/- 8.4% when compared with control values. Mean fiber area (average of slow and fast fibers) increased significantly by 27.8 +/- 6.0% in the stretched anterior latissimus dorsi. There were no differences in the percentage of slow fibers or volume density of noncontractile tissue. These data indicate that muscle adapts differently to intermittent stretch than it does to chronic stretch despite an equivalent load and stretch duration. In contrast to chronic stretch, 5 days of intermittent stretch produces muscle fiber hypertrophy without fiber hyperplasia.

Muscle fiber formation and fiber hypertrophy during the onset of stretch-overload

1990 ◽  
Vol 259 (1) ◽  
pp. C92-C102 ◽  
Author(s):  
S. E. Alway ◽  
W. J. Gonyea ◽  
M. E. Davis
Keyword(s):  
Muscle Mass ◽  
Cross Sectional Area ◽  
Fiber Formation ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fiber Splitting ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Nitric Acid Digestion ◽  
Animal Control

The contributions of fiber hypertrophy and new fiber formation to the onset of stretch-induced muscle enlargement were evaluated in the anterior latissimus dorsi (ALD) of adult Japanese quails, because it was not known whether the mechanisms which initiate new fiber formation were dependent on first achieving significant fiber hypertrophy. A weight corresponding to 10% of the bird's body mass was attached to one wing, and eight birds were killed after each day during the first week of stretch. Muscle mass was significantly increased after 48 h of stretch; however, the elevation in nonmuscle tissue accounted for this increase. Muscle mass corrected for non-muscle tissue was significantly greater than the intra-animal control by the fourth day of stretch. Mean fiber cross-sectional area did not change during days 0-6, but cross-sectional area was 30.0 +/- 17.2% greater than the intra-animal control areas at day 7. Fiber number determined after nitric acid digestion of connective tissue was 27.1 +/- 5.8% greater than the intra-animal control at days 5-7 of stretch, but the number of fibers in the control muscles at days 5 and 6 were lower than at day 0. Thus new fiber formation was not preceded by significant fiber hypertrophy. These results fail to support a mechanism for new fiber formation which involves fiber splitting from hypertrophied myofibers during the first week of stretch.

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.

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)

Progressive stretch overload of skeletal muscle results in hypertrophy before hyperplasia

1993 ◽  
Vol 75 (3) ◽  
pp. 1263-1271 ◽  
Author(s):  
J. Antonio ◽  
W. J. Gonyea
Keyword(s):  
Latissimus Dorsi ◽  
Critical Size ◽  
Muscle Length ◽  
Progressive Increase ◽  
Right Wing ◽  
Left Wing ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
The Right ◽  
Large Muscle

Intermittent stretch of the anterior latissimus dorsi (ALD) muscle produces fiber hypertrophy without fiber hyperplasia (J. Appl. Physiol. 74: 1893–1898, 1993). This study was undertaken to determine if a progressive increase in load and duration of stretch would induce extremely large muscle fiber areas or if the fibers would reach a critical size before the onset of fiber hyperplasia. Weights ranging from 10 to 35% of the bird's mass were attached to the right wing of 26 adult quail while the left wing served as the intra-animal control. The stretch protocol was as follows: day 1 (10% wt), days 2 and 3 (rest), day 4 (15% wt), days 5–7 (rest), day 8 (20% wt), days 9 and 10 (rest), days 11–14 (25% wt), days 15 and 16 (rest), and days 17–38 (35% wt). Birds were killed after 12, 16, 20, 24, and 28 days of stretch not including rest days. Muscle mass increased 174% (12 days), 196% (16 days), 225% (20 days), 264% (24 days), and 318% (28 days). Muscle length increased 60% (12 days), 34% (16 days), 59% (20 days), 50% (24 days), and 51% (28 days). Mean fiber area increased 111% (12 days), 142% (16 days), 75% (20 days), 90% (24 days), and 39% (28 days). Fiber number, which was measured histologically, increased significantly by 82% only in the 28 days of stretch group. The percentage of slow tonic fibers did not change for any of the time points examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertrophy and proliferation of skeletal muscle fibers from aged quail

1995 ◽  
Vol 78 (1) ◽  
pp. 293-299 ◽  
Author(s):  
J. A. Carson ◽  
M. Yamaguchi ◽  
S. E. Alway
Keyword(s):  
Muscle Mass ◽  
Fiber Type ◽  
Right Wing ◽  
Left Wing ◽  
Cross Sectional ◽  
Anterior Latissimus Dorsi ◽  
Fiber Number ◽  
Fiber Type Distribution ◽  
Distribution Shifts ◽  
The Right

The purpose of this study was to determined whether fibers in the anterior latissimus dorsi (ALD) muscle from aged Japanese quail have decreased hypertrophic or proliferative responses to 30 days of stretch overload compared with fibers from adult birds. Two groups of quail were studied, 12-wk-old quail (adult; n = 16) and 90-wk-old quail (aged; n = 16). The left wing of each bird was overloaded with a weight corresponding to 10% of the bird's body weight, and the right wing served as the intra-animal control. Quails were killed after 30 days of stretch overload. Total fiber number was quantified by counting all the fibers in a transverse section from the midbelly of the ALD muscle. ALD muscles in aged quails retained the capacity to increase their muscle mass (145%), total fiber number (49%), and fiber cross-sectional area (54%) in response to stretch overload. The ALD muscle in aged quail had a significantly lower increase in muscle mass (33%) and mass corrected for nonmuscle tissue (36%) compared with the ALD from young adult birds. Age had no effect on fiber type distribution shifts with stretch. These results suggest that although muscles in old birds have a substantial ability to adapt to enlarge, stretch-induced hypertrophy is attenuated in muscles from old quail.

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.

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.

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