Lactate transport studied in sarcolemmal giant vesicles from human muscle biopsies: relation to training status

1994 ◽  
Vol 77 (4) ◽  
pp. 1858-1862 ◽  
Author(s):  
H. Pilegaard ◽  
J. Bangsbo ◽  
E. A. Richter ◽  
C. Juel
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
High Volume ◽  
Type I ◽  
Training Status ◽  
Transport Capacity ◽  
Lactate Transport ◽  
Giant Vesicles ◽  
Trained Subjects ◽  
Muscle Biopsies

The present study examined sarcolemmal lactate transport capacity in humans of widely different training status. Muscle biopsies were obtained from m. vastus lateralis in 39 subjects divided into untrained (n = 13), trained (n = 7), and athlete [sprint runners (n = 2), endurance runners (n = 5), triathletes (n = 3), and road (n = 6) and track (n = 3) bicyclists] groups. From the biopsy sample giant vesicles were produced with collagenase treatment to determine the sarcolemmal lactate transport capacity, and histochemical analyses were made. The athletes had a higher capacity to transport lactate than the untrained and trained subjects (P < 0.01). Within the group of athletes, the bicyclists had a higher lactate transport capacity than the runners (P < 0.05), whereas there was no difference among trained subjects, runners, and triathletes. The lactate transport capacity was related to the occurrence of type I muscle fibers (r = 0.48, P < 0.01). The present results suggest that the capacity to transport lactate is higher in athletes than in untrained and less trained subjects. It might indicate that lactate transport capacity in human skeletal muscle can be changed by a high volume of training including frequent high-intensity sessions. In addition, sarcolemmal lactate transport capacity appears to be related to the fiber type distribution of a muscle.

scholarly journals Effects of fatigue and training on sarcoplasmic reticulum Ca2+ regulation in human skeletal muscle

2002 ◽  
Vol 92 (3) ◽  
pp. 912-922 ◽  
Author(s):  
Jia L. Li ◽  
Xiao N. Wang ◽  
Steve F. Fraser ◽  
Michael F. Carey ◽  
Tim V. Wrigley ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Human Muscle ◽  
Training Status ◽  
Type Ii ◽  
Muscle Biopsies ◽  
And Training

Little is known about fatigue and training effects on sarcoplasmic reticulum (SR) function in human muscle, and we therefore investigated this in eight untrained controls (UT), eight endurance-trained (ET), and eight resistance-trained athletes (RT). Muscle biopsies (vastus lateralis) taken at rest and after 50 maximal quadriceps contractions (180°/s, 0.5 Hz) were analyzed for fiber composition, metabolites and maximal SR Ca2+ release, Ca2+ uptake, and Ca2+-ATPase activity. Fatigue reduced ( P < 0.05) Ca2+ release (42.1 ± 3.8%, 43.4 ± 3.9%, 31.3 ± 6.1%), Ca2+ uptake (43.0 ± 5.2%, 34.1 ± 4.6%, 28.4 ± 2.8%), and Ca2+-ATPase activity (38.6 ± 4.2%, 48.5 ± 5.7%, 29.6 ± 5.0%), in UT, RT, and ET, respectively. These decreases were correlated with fatigability and with type II fiber proportion ( P < 0.05). Resting SR measures were correlated with type II proportion ( r ≥ 0.51, P < 0.05). ET had lower resting Ca2+ release, Ca2+ uptake, and Ca2+-ATPase ( P < 0.05) than UT and RT ( P < 0.05), probably because of their lower type II proportion; only minor effects were found in RT. Thus SR function is markedly depressed with fatigue in controls and in athletes, is dependent on fiber type, and appears to be minimally affected by chronic training status.

Genetic and other determinants of AMP deaminase activity in healthy adult skeletal muscle

1998 ◽  
Vol 85 (4) ◽  
pp. 1273-1278 ◽  
Author(s):  
Barbara Norman ◽  
Donna K. Mahnke-Zizelman ◽  
Amy Vallis ◽  
Richard L. Sabina
Keyword(s):  
Skeletal Muscle ◽  
Enzyme Activity ◽  
Mutant Allele ◽  
Fiber Type ◽  
Type I ◽  
Training Status ◽  
Amp Deaminase ◽  
Normal Allele ◽  
Relative Percentage ◽  
Type I Fibers

AMPD1 genotype, relative fiber type composition, training status, and gender were evaluated as contributing factors to the reported variation in AMP deaminase enzyme activity in healthy skeletal muscle. Multifactorial correlative analyses demonstrate that AMPD1 genotype has the greatest effect on enzyme activity. An AMPD1 mutant allele frequency of 13.7 and a 1.7% incidence of enzyme deficiency was found across 175 healthy subjects. Homozygotes for the AMPD1 normal allele have high enzyme activities, and heterozygotes display intermediate activities. When examined according to genotype, other factors were found to affect variability as follows: AMP deaminase activity in homozygotes for the normal allele exhibits a negative correlation with the relative percentage of type I fibers and training status. Conversely, residual AMP deaminase activity in homozygotes for the mutant allele displays a positive correlation with the relative percentage of type I fibers. Opposing correlations in different homozygous AMPD1 genotypes are likely due to relative fiber-type differences in the expression of AMPD1 and AMPD3 isoforms. Gender also contributes to variation in total skeletal muscle AMP deaminase activity, with normal homozygous and heterozygous women showing only 85–88% of the levels observed in genotype-matched men.

In vitro human masseter muscle hypersensitivity: a possible explanation for increase in masseter tone

1996 ◽  
Vol 80 (5) ◽  
pp. 1547-1553 ◽  
Author(s):  
P. J. Adnet ◽  
H. Reyford ◽  
B. M. Tavernier ◽  
T. Etchrivi ◽  
I. Krivosic ◽  
...  
Keyword(s):  
Masseter Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Threshold Concentration ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Cross Sectional ◽  
Significant Difference ◽  
Maximal Tension

To determine whether a difference in fiber-type caffeine and Ca2+ sensitivities exists between human masseter and vastus lateralis skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers from 13 masseter and 18 vastus lateralis muscles. Caffeine sensitivity was defined as the threshold concentration inducing > 10% of the maximal tension obtained after the fiber was loaded with a 1.6 x 10(-2) mM Ca2+ solution for 30 s. Significant difference in the mean caffeine sensitivity was found between type I masseter fibers [2.57 +/- 1.32 (SD) mM] vs. type I (6.02 +/- 1.74 mM) and type II vastus lateralis fibers (11.25 +/- 3.13 mM). Maximal Ca(2+)-activated force per cross-sectional area was significantly different between masseter and vastus lateralis fibers. However, the Ca2+ concentration corresponding to half-maximal tension (pCa50) was not significantly different between type I masseter (pCa50 5.9 +/- 0.02) and type I vastus lateralis muscle (pCa50 6.01 +/- 0.08). These results suggest that the increase in caffeine sensitivity of masseter muscle reflects the presence of a low reactivity threshold of the sarcoplasmic reticulum.

Carnitine metabolism in human muscle fiber types during submaximal dynamic exercise

1996 ◽  
Vol 80 (3) ◽  
pp. 1061-1064 ◽  
Author(s):  
D. Constantin-Teodosiu ◽  
S. Howell ◽  
P. L. Greenhaff
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Group Formation ◽  
Free Carnitine ◽  
Muscle Fiber Types ◽  
Type I ◽  
Fiber Types ◽  
Carnitine Metabolism ◽  
Type I Fibers

The effect of prolonged exhaustive exercise on free carnitine and acetylcarnitine concentrations in mixed-fiber skeletal muscle and in type I and II muscle fibers was investigated in humans. Needle biopsy samples were obtained from the vastus lateralis of six subjects immediately after exhaustive one-legged cycling at approximately 75% of maximal O2 uptake from both the exercised and nonexercised (control) legs. In the resting (control) leg, there was no difference in the free carnitine concentration between type I and II fibers (20.36 +/- 1.25 and 20.51 +/- 1.16 mmol/kg dry muscle, respectively) despite the greater potential for fat oxidation in type I fibers. However, the acetylcarnitine concentration was slightly greater in type I fibers (P < 0.01). During exercise, acetylcarnitine accumulation occurred in both muscle fiber types, but accumulation was greatest in type I fibers (P < 0.005). Correspondingly, the concentration of free carnitine was significantly lower in type I fibers at the end of exercise (P < 0.001). The sum of free carnitine and acetylcarnitine concentrations in type I and II fibers at rest was similar and was unchanged by exercise. In conclusion, the findings of the present study support the suggestion that carnitine buffers excess acetyl group formation during exercise and that this occurs in both type I and II fibers. However, the greater accumulation of acetylcarnitine in type I fibers during prolonged exercise probably reflects the greater mitochondrial content of this fiber type.

Human and Rat Skeletal Muscle Adaptations to Spinal Cord Injury

2003 ◽  
Vol 28 (3) ◽  
pp. 491-500 ◽  
Author(s):  
Chris M. Gregory ◽  
Krista Vandenborne ◽  
Michael J. Castro ◽  
G. Alton Dudley
Keyword(s):  
Skeletal Muscle ◽  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Type I ◽  
Glycerol Phosphate ◽  
Cross Sectional ◽  
Muscle Plasticity ◽  
Cord Injury

Results of studies of rodent skeletal muscle plasticity are often extrapolated to humans. However, responses to "disuse" may be species specific, in part because of different inherent properties of anatomically similar muscles. Thus, this study quantified human and rat m. vastus lateralis (VL) fiber adaptations to 11 weeks of spinal cord injury (SCI). The m. VL was taken from 8 young (54 d) male Charles River rats after T-9 laminectomy (n = 4) or sham surgery (n = 4). In addition, the m. VL was biopsied in 7 able-bodied and in 7 SCI humans (31.3 ± 4.7 years, mean ± SE). Samples were sectioned and fibers were analyzed for type (I, IIa, IIb/x), cross-sectional area (CSA), succinate dehydrogenase (SDH), α-glycerol-phosphate dehydrogenase (GPDH), and actomyosin adenosine triphosphatase (qATPase) activities. Rat fibers had 1.5- to 2-fold greater SDH and GPDH activities while their fibers were 60% the size of those in humans. The most striking differences, however, were the absence of slow fibers in the rat and its four-fold greater proportion of IIb/x fibers (80% vs. 16% of the CSA) compared to humans. SCI decreased SDH activity more in rats whereas atrophy and IIa to IIb/x fiber shift occurred to a greater extent in humans. It is suggested that the rat is a reasonable model for studying the predominant response to SCI, atrophy. However, its high proportion of IIb/x fibers limits evaluation of the mechanical consequences of shifting to "faster" contractile machinery after SCI. Key words: enzyme, fiber type, disuse, biopsy

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.

Calcium-activated force of human muscle fibers following a standardized eccentric contraction

2010 ◽  
Vol 299 (6) ◽  
pp. C1409-C1417 ◽  
Author(s):  
Seung Jun Choi ◽  
Jeffrey J. Widrick
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Mechanical Strain ◽  
Eccentric Contraction ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Specific Force ◽  
Shortening Velocity ◽  
Hybrid Fibers ◽  
Fixed End

Peak Ca2+-activated specific force (force/fiber cross-sectional area) of human chemically skinned vastus lateralis muscle fiber segments was determined before and after a fixed-end contraction or an eccentric contraction of standardized magnitude (+0.25 optimal fiber length) and velocity (0.50 unloaded shortening velocity). Fiber myosin heavy chain (MHC) isoform content was assayed by SDS-PAGE. Posteccentric force deficit, a marker of damage, was similar for type I and IIa fibers but threefold greater for type IIa/IIx hybrid fibers. A fixed-end contraction had no significant effect on force. Multiple linear regression revealed that posteccentric force was explained by a model consisting of a fiber type-independent and a fiber type-specific component ( r2 = 0.91). Preeccentric specific force was directly associated with a greater posteccentric force deficit. When preeccentric force was held constant, type I and IIa fibers showed identical susceptibility to damage, while type IIa/IIx fibers showed a significantly greater force loss. This heightened sensitivity to damage was directly related to the amount of type IIx MHC in the hybrid fiber. Our model reveals a fiber-type sensitivity of the myofilament lattice or cytoskeleton to mechanical strain that can be described as follows: type IIa/IIx > type IIa = type I. If these properties extend to fibers in vivo, then alterations in the number of type IIa/IIx fibers may modify a muscle's susceptibility to eccentric damage.

scholarly journals The influence of training status, age, and muscle fiber type on cycling efficiency and endurance performance

2013 ◽  
Vol 115 (5) ◽  
pp. 723-729 ◽  
Author(s):  
James G. Hopker ◽  
Damian A. Coleman ◽  
Hannah C. Gregson ◽  
Simon A. Jobson ◽  
Tobias Von der Haar ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Power Output ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Cycling Performance ◽  
Muscle Fiber Type ◽  
Type I ◽  
Maximal Heart Rate ◽  
Training Status ◽  
Cycling Efficiency

The purpose of this study was to assess the influence of age, training status, and muscle fiber-type distribution on cycling efficiency. Forty men were recruited into one of four groups: young and old trained cyclists, and young and old untrained individuals. All participants completed an incremental ramp test to measure their peak O2 uptake, maximal heart rate, and maximal minute power output; a submaximal test of cycling gross efficiency (GE) at a series of absolute and relative work rates; and, in trained participants only, a 1-h cycling time trial. Finally, all participants underwent a muscle biopsy of their right vastus lateralis muscle. At relative work rates, a general linear model found significant main effects of age and training status on GE ( P < 0.01). The percentage of type I muscle fibers was higher in the trained groups ( P < 0.01), with no difference between age groups. There was no relationship between fiber type and cycling efficiency at any work rate or cadence combination. Stepwise multiple regression indicated that muscle fiber type did not influence cycling performance ( P > 0.05). Power output in the 1-h performance trial was predicted by average O2 uptake and GE, with standardized β-coefficients of 0.94 and 0.34, respectively, although some mathematical coupling is evident. These data demonstrate that muscle fiber type does not affect cycling efficiency and was not influenced by the aging process. Cycling efficiency and the percentage of type I muscle fibers were influenced by training status, but only GE at 120 revolutions/min was seen to predict cycling performance.

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 Skeletal muscle lipid droplets are resynthesized before being coated with perilipin proteins following prolonged exercise in elite male triathletes

2020 ◽  
Vol 318 (3) ◽  
pp. E357-E370 ◽  
Author(s):  
Emily F. P. Jevons ◽  
Kasper D. Gejl ◽  
Juliette A. Strauss ◽  
Niels Ørtenblad ◽  
Sam O. Shepherd
Keyword(s):  
Prolonged Exercise ◽  
Fiber Type ◽  
Moderate Intensity ◽  
Type I ◽  
Muscle Lipid ◽  
Confocal Immunofluorescence Microscopy ◽  
Confocal Immunofluorescence ◽  
Skeletal Muscle Lipid ◽  
Type I Fibers ◽  
Muscle Biopsies

Intramuscular triglycerides (IMTG) are a key substrate during prolonged exercise, but little is known about the rate of IMTG resynthesis in the postexercise period. We investigated the hypothesis that the distribution of the lipid droplet (LD)-associated perilipin (PLIN) proteins is linked to IMTG storage following exercise. Fourteen elite male triathletes (27 ± 1 yr, 66.5 ± 1.3 mL·kg−1·min−1) completed 4 h of moderate-intensity cycling. During the first 4 h of recovery, subjects received either carbohydrate or H2O, after which both groups received carbohydrate. Muscle biopsies collected pre- and postexercise and 4 and 24 h postexercise were analyzed using confocal immunofluorescence microscopy for fiber type-specific IMTG content and PLIN distribution with LDs. Exercise reduced IMTG content in type I fibers (−53%, P = 0.002), with no change in type IIa fibers. During the first 4 h of recovery, IMTG content increased in type I fibers ( P = 0.014), but was not increased more after 24 h, where it was similar to baseline levels in both conditions. During recovery the number of LDs labeled with PLIN2 (70%), PLIN3 (63%), and PLIN5 (62%; all P < 0.05) all increased in type I fibers. Importantly, the increase in LDs labeled with PLIN proteins only occurred at 24 h postexercise. In conclusion, IMTG resynthesis occurs rapidly in type I fibers following prolonged exercise in highly trained individuals. Furthermore, increases in IMTG content following exercise preceded an increase in the number of LDs labeled with PLIN proteins. These data, therefore, suggest that the PLIN proteins do not play a key role in postexercise IMTG resynthesis.

Sign in / Sign up

Export Citation Format

Share Document