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

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.

1989 ◽  
Vol 66 (2) ◽  
pp. 771-781 ◽  
Author(s):  
S. E. Alway ◽  
P. K. Winchester ◽  
M. E. Davis ◽  
W. J. Gonyea

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.


1993 ◽  
Vol 25 (Supplement) ◽  
pp. S33
Author(s):  
M. Esbj??rnsson ◽  
Y. H-Westing ◽  
P. Balsom ◽  
B. Sj??din ◽  
E. Jansson

1992 ◽  
Vol 263 (5) ◽  
pp. R1093-R1098 ◽  
Author(s):  
S. K. Powers ◽  
D. Criswell ◽  
F. K. Lieu ◽  
S. Dodd ◽  
H. Silverman

Limited data exist concerning the effects of exercise training on cellular oxidative capacity in the diaphragm of senescent animals. In this study we examined the changes in cellular oxidative capacity, muscle cell cross-sectional area (CSA), and capillarity within the costal diaphragm of senescent animals after a 10-wk endurance-training program. Twelve 24-mo-old female Fischer 344 rats were divided into either a sedentary control group (n = 6) or exercise training group (n = 6). The trained animals exercised on a motor-driven treadmill (60 min/day, 5 days/wk) at a work rate equal to approximately 55-65% VO2max. Capillaries were identified histologically and fiber types determined using adenosinetriphosphatase (ATPase) histochemistry. Succinate dehydrogenase (SDH) activity and CSA in individual fibers were measured using a computerized image analysis system. Exercise training did not increase (P > 0.05) the capillary-to-fiber ratio for any fiber type. However, training significantly decreased CSA (P < 0.05) and increased capillary density (capillary number/CSA) (P < 0.05) in type I, type IIa, and type IIb fibers. Furthermore, exercise training resulted in small but significant increase in SDH activity (P < 0.05) in type I and IIa fibers, whereas training did not alter SDH activity (P > 0.05) in type IIb fibers. These data demonstrate that endurance training in senescent animals results in small relative improvements in both oxidative capacity and capillary density in costal diaphragmatic type I and IIa muscle fibers. The increase in both capillary density and fiber SDH activity was largely due to a reduction in fiber CSA.


1998 ◽  
Vol 84 (3) ◽  
pp. 902-907 ◽  
Author(s):  
Michael J. Plyley ◽  
Barbara J. Olmstead ◽  
Earl G. Noble

The time course of angiogenesis during hypertrophy of the rat plantaris muscle was studied by using a unilateral, synergistic ablation model. Animals ( n = 6/group) were euthanized 2, 5, 7, 15, 21, and 30 days postmyectomy. Sections from both the hypertrophied and contralateral muscles were simultaneously stained for capillaries and muscle fiber type. Mean fiber cross-sectional area (FA) and various indexes of capillarity were determined by using a video analysis system. The capillary supply to individual fibers, assessed as the FA supplied per capillary contact, remained unchanged until day 21 (compared with day 2) and exhibited a significant increase at day 30. Analysis of the time course of capillary development on the basis of the number of capillary contacts per fiber, and of hypertrophy on the basis of FA, yielded half-lives of 10.1 and 11.2 days, respectively. It was concluded that angiogenesis during muscle overload is tightly coupled to the changes in FA, which could suggest that the two processes are initiated and/or driven by some common factor(s).


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