Progressive metabolite changes in individual human muscle fibers with increasing work rates

1987 ◽  
Vol 252 (6) ◽  
pp. C630-C639 ◽  
Author(s):  
J. L. Ivy ◽  
M. M. Chi ◽  
C. S. Hintz ◽  
W. M. Sherman ◽  
R. P. Hellendall ◽  
...  
Keyword(s):  
Blood Lactate ◽  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Lactate Concentration ◽  
Work Load ◽  
Bicycle Ergometer ◽  
Almost All ◽  
Fast Twitch

Muscle biopsies were obtained from vastus lateralis muscles of four volunteers exercising at increasing work rates on a bicycle ergometer. Samples were taken at rest (t1), after a work load 23% below the blood lactate threshold (t2), 23% above this threshold (t3), and at exhaustion (t4). Individual muscle fibers were typed by their lactate dehydrogenase and adenylokinase levels and assayed for lactate, glucose-6-phosphate, and malate, (which preliminary data indicated to be the most responsive to increased activity) as well as ATP and phosphocreatine. The results in three of the four cases indicated that by the time of the t2 sample, almost all fibers, regardless of type, had been recruited. Additionally, there were no major differences in lactate concentration between type 1 and 2 fibers from muscle samples taken at t1, t2, and t3. It is concluded that in a muscle with fast-twitch glycolytic and slow-twitch oxidative fibers, all fibers share in the contraction to a substantial degree, even at moderate work loads, and that both the type 1 and 2 fibers contribute significantly to the initial rise in blood lactate during a graded exercise task. Metabolite responses in type 2 fibers differed in certain respects among the four participants. This is attributed to differences in their training backgrounds and consequent differences in type 2 fiber oxidative enzyme levels.

scholarly journals Expression of type-specific MHC isoforms in rat intrafusal muscle fibers.

1992 ◽  
Vol 40 (2) ◽  
pp. 293-307 ◽  
Author(s):  
J Kucera ◽  
J M Walro ◽  
L Gorza
Keyword(s):  
Muscle Fibers ◽  
Fiber Types ◽  
Hindlimb Muscles ◽  
Intrafusal Fibers ◽  
Intrafusal Muscle Fibers ◽  
Intrafusal Fiber Types ◽  
Fast Twitch ◽  
Developing Muscle

Myosin heavy chain (MHC) expression by intrafusal fibers was studied by immunocytochemistry to determine how closely it parallels MHC expression by extrafusal fibers in the soleus and tibialis anterior muscles of the rat. Among the MHC isoforms expressed in extrafusal fibers, only the slow-twitch MHC of Type 1 extrafusal fibers was expressed along much of the fibers. Monoclonal antibodies (MAb) specific for this MHC bound to the entire length of bag2 fibers and the extracapsular region of bag1 fibers. The fast-twitch MHC isoform strongly expressed by bag2 and chain fibers had an epitope not recognized by MAb to the MHC isoforms characteristic of developing muscle fibers or the three subtypes (2A, 2B, 2X) of Type 2 extrafusal fibers. Therefore, intrafusal fibers may express a fast-twitch MHC that is not expressed by extrafusal fibers. Unlike extrafusal fibers, all three intrafusal fiber types bound MAb generated against mammalian heart and chicken limb muscles. The similarity of the fast-twitch MHC of bag2 and chain fibers and the slow-tonic MHC of bag1 and bag2 fibers to the MHC isoforms expressed in avian extrafusal fibers suggests that phylogenetically primitive MHCs might persist in intrafusal fibers. Data are discussed relative to the origin and regional regulation of MHC isoforms in intrafusal and extrafusal fibers of rat hindlimb muscles.

and EMG Activity Kinetics During Moderate and Severe Constant Work Rate Exercise in Trained Cyclists

2004 ◽  
Vol 29 (6) ◽  
pp. 758-772 ◽  
Author(s):  
Christophe Cleuziou ◽  
Stéphane Perrey ◽  
Fabio Borrani ◽  
Anne Marie Lecoq ◽  
Daniel Courteix ◽  
...  
Keyword(s):  
Slow Component ◽  
Vastus Lateralis ◽  
Bicycle Ergometer ◽  
Lower Limbs ◽  
Emg Activity ◽  
Power Frequency ◽  
Severe Exercise ◽  
Median Power Frequency ◽  
Almost All ◽  
Fast Twitch

The purpose of this study was to compare O2 uptake [Formula: see text] and muscle electromyography activity kinetics during moderate and severe exercise to test the hypothesis of progressive recruitment of fast-twitch fibers in the explanation of the [Formula: see text] slow component. After an incremental test to exhaustion, 7 trained cyclists (mean ± SD, 61.4 ± 4.2 ml•min−1•kg−1) performed several square-wave transitions for 6 min at moderate and severe intensities on a bicycle ergometer. The [Formula: see text] response and the electrical activity (i.e., median power frequency, MDF) of the quadriceps vastus lateralis and vastus medialis of both lower limbs were measured continuously during exercise. After ∼2 to 3 min of exercise onset, MDF values increased similarly during moderate and severe exercise for almost all muscles whereas a [Formula: see text] slow component occurred during severe exercise. There was no relationship between the increase of MDF values and the magnitude of the [Formula: see text] slow component during the severe exercise. These results suggest that the origin of the slow component may not be due to the progressive recruitment of fast-twitch fibers. Key words: median power frequency, O2 uptake, recruitment of fast-twitch fibers, [Formula: see text]slow component

scholarly journals A Novel Method for Classification of Running Fatigue Using Change-Point Segmentation

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4729 ◽  
Author(s):  
Taha Khan ◽  
Lina E. Lundgren ◽  
Eric Järpe ◽  
M. Charlotte Olsson ◽  
Pelle Viberg
Keyword(s):  
Random Forest ◽  
Blood Lactate ◽  
Change Point ◽  
Vastus Lateralis ◽  
Lactate Concentration ◽  
Treadmill Running ◽  
Vastus Lateralis Muscle ◽  
Semg Signal ◽  
Novel Method

Blood lactate accumulation is a crucial fatigue indicator during sports training. Previous studies have predicted cycling fatigue using surface-electromyography (sEMG) to non-invasively estimate lactate concentration in blood. This study used sEMG to predict muscle fatigue while running and proposes a novel method for the automatic classification of running fatigue based on sEMG. Data were acquired from 12 runners during an incremental treadmill running-test using sEMG sensors placed on the vastus-lateralis, vastus-medialis, biceps-femoris, semitendinosus, and gastrocnemius muscles of the right and left legs. Blood lactate samples of each runner were collected every two minutes during the test. A change-point segmentation algorithm labeled each sample with a class of fatigue level as (1) aerobic, (2) anaerobic, or (3) recovery. Three separate random forest models were trained to classify fatigue using 36 frequency, 51 time-domain, and 36 time-event sEMG features. The models were optimized using a forward sequential feature elimination algorithm. Results showed that the random forest trained using distributive power frequency of the sEMG signal of the vastus-lateralis muscle alone could classify fatigue with high accuracy. Importantly for this feature, group-mean ranks were significantly different (p < 0.01) between fatigue classes. Findings support using this model for monitoring fatigue levels during running.

Effects of glycogen depletion and work load on postexercise O2 consumption and blood lactate

1979 ◽  
Vol 47 (3) ◽  
pp. 514-521 ◽  
Author(s):  
S. S. Segal ◽  
G. A. Brooks
Keyword(s):  
Blood Lactate ◽  
Slow Component ◽  
Minute Ventilation ◽  
Co2 Flux ◽  
Work Load ◽  
Bicycle Ergometer ◽  
Co2 Production ◽  
O2 Consumption ◽  
Glycogen Depletion ◽  
Heavy Exercise

To study a possible relationship between blood lactate and O2 consumption (VO2) after exercise, 11 male subjects exercised on a bicycle ergometer at moderate and heavy work loads in both normal glycogen and glycogen-depleted states. At rest, glycogen depletion resulted in significantly lowered blood glucose and lactate concentrations, CO2 production (VCO2), respiratory exchange ratio (R), and minute ventilation (VE). With the exception of glucose, these variables changed more in response to heavy exercise (HE: 2 min at a mean of 1,750 kg.m/min) than to moderate exercise (ME: 2 min at a mean of 1,000 kg.m/min). At either work load, VCO2, R, and lactate showed consistently greater responses in the normal glycogen state. The slope of the initial component of the postexercise VO2 curve was unaffected by either work load or lactate. Although the slope of the slow component of the postexercise VO2 curve became significantly more negative after HE, it was unaffected by the level of lactate. These results are inconsistent with the hypothesis of a “lactacid O2 debt.” Exercise intensity was the predominant factor influencing the magnitude and kinetics of postexercise VO2. Glycogen depletion resulted in lower VCO2, R, and blood lactate, but higher VE during heavy exercise. The results suggest that factors, in addition to CO2 flux to the lungs, influence VE during exercise.

scholarly journals Size and Proportions of Slow-Twitch and Fast-Twitch Muscle Fibers in Human Costal Diaphragm

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Marija Meznaric ◽  
Erika Cvetko
Keyword(s):  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Hybrid Fibers ◽  
Cross Sectional ◽  
Myosin Heavy Chain Isoform ◽  
Diaphragmatic Muscle ◽  
Fast Twitch Muscle ◽  
The Mean ◽  
Slow Twitch ◽  
Fast Twitch

Smaller diaphragmatic motor unit potentials (MUPs) compared to MUPs of limb muscles lead to the hypothesis that diaphragmatic muscle fibers, being the generators of MUPs, might be also smaller. We compared autopsy samples of costal diaphragm and vastus lateralis of healthy men with respect to fibers’ size and expression of slow myosin heavy chain isoform (MyHC-1) and fast 2A isoform (MyHC-2A). Diaphragmatic fibers were smaller than fibers in vastus lateralis with regard to the mean minimal fiber diameter of slow-twitch (46.8 versus 72.2 μm,p<0.001), fast-twitch (45.1 versus 62.4 μm,p<0.001), and hybrid fibers (47.3 versus 65.0 μm,p<0.01) as well as to the mean fiber cross-sectional areas of slow-twitch (2376.0 versus 5455.9 μm2,p<0.001), fast-twitch (2258.7 versus 4189.7 μm2,p<0.001), and hybrid fibers (2404.4 versus 4776.3 μm2,p<0.01). The numerical proportion of slow-twitch fibers was higher (50.2 versus 36.3%,p<0.01) in costal diaphragm and the numerical proportion of fast-twitch fibers (47.2 versus 58.7%,p<0.01) was lower. The numerical proportion of hybrid fibers did not differ. Muscle fibers of costal diaphragm have specific characteristics which support increased resistance of diaphragm to fatigue.

Effects of previous exercise with arms or legs on metabolism and performance in exhaustive exercise

1975 ◽  
Vol 38 (5) ◽  
pp. 763-767 ◽  
Author(s):  
J. Karlsson ◽  
F. Bonde-Petersen ◽  
J. Henriksson ◽  
H. G. Knuttgen
Keyword(s):  
Blood Lactate ◽  
Vastus Lateralis ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Exercise Bout ◽  
Creatine Phosphate ◽  
The Body ◽  
Exhaustive Exercise ◽  
Leg Exercise ◽  
Muscle Groups

The ability of additional muscles to perform after certain other muscles of the body had been exercised to exhaustion was studied in three male subjects. Exhaustive exercise was performed in two series: series L-A, a bout of leg exercise preceded a bout of arm exercise; series A-L, arm preceded leg (6-min recovery between bouts). Biopsies were taken during the course of each experiment from both the deltoideus and vastus lateralis muscles for determination of ATP, creatine phosphate, lactate, and pyruvate. Exhaustive exercise led to marked elevations in lactate and decreases in ATP and CP in exercised muscle and marked increases in blood lactate concentration. Similar changes, especially in lactate, were observed during and after the first exercise bout in nonexercised muscle. When arm or leg exercise was performed as the second bout, decreases in performance time were observed as compared to performance as the initial bout. It is suggested that the performance potential of muscle is decreased because of internal changes elicited by elevated blood lactate and/or blood H+ concentrations brought about by other muscle groups previously exercised to exhaustion.

Existence of host-related DNA sequences in the schistosome genome

Parasitology ◽  
1991 ◽  
Vol 102 (3) ◽  
pp. 397-403 ◽  
Author(s):  
Y. Iwamura ◽  
Y. Irie ◽  
R. Kominami ◽  
T. Nara ◽  
K. Yasuraoka
Keyword(s):  
Dna Sequences ◽  
Extra Chromosome ◽  
Repetitive Sequences ◽  
Dna Fingerprints ◽  
Alu Sequence ◽  
Type C ◽  
Almost All ◽  
Intracisternal A Particle

DNA sequences homologous to the mouse intracisternal A particle and endogenous type C retrovirus were detected in the DNAs ofSchistosoma japonicumadults andS. mansonieggs. Furthermore, other kinds of repetitive sequences in the host genome such as mouse type 1 Alu sequence (B1), mouse type 2 Alu sequence (B2) and mo-2 sequence, a mouse mini-satellite, were also detected in the DNAs from adults and eggs ofS. japonicumand eggs ofS. mansoni. Almost all of the sequences described above were absent in the DNAs ofS. mansoniadults. The DNA fingerprints of schistosomes, using the mo-2 sequence, were indistinguishable from each other and resembled those of their murine hosts. Moreover, the mo-2 sequence was hypermethylated in the DNAs of schistosomes and its amount was variable in them. These facts indicate that host-related sequences are actually present in schistosomes and that the mo-2 repetitive sequence exists probably in extra-chromosome.

Desmopressin parenteral bei VWD 1, VWD 2A und Thrombozytopathie

2011 ◽  
Vol 31 (S 01) ◽  
pp. S29-S33 ◽  
Author(s):  
H. Pollmann ◽  
B. Siegmund
Keyword(s):  
Side Effects ◽  
Disease Type ◽  
Von Willebrand Disease ◽  
Occlusion Time ◽  
Almost All ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Ristocetin Cofactor

SummaryDesmopressin (DDAVP, Minirin® parenteral), which induces the release of von-Willebrand factor from endogenous stores, is indicated in von Willebrand disease type 1 (VWD 1). In the present study effectiveness of DDAVP was tested and side effects were recorded in patients with VWD 1, von Willebrand disease type 2 (VWD 2) or thrombocytopathy (TCP). Patients, methods Subjects were analysed prior to and after Minirin parenteral infusion (0.4 μg/kg body weight (b.w.) over 60 minutes) for partial thromboplastin time (PTT, seconds), ADP/epinephrine triggered plateletfunction analyzer (PFA-100) occlusion time (seconds), factor VIII activity (FVIII, %), VWF as ristocetin cofactor activity (VWF:RCo, %) and VWF antigen (VWF:Ag, %). Side effects of DDAVP during operative interventions were recorded per questionnaires by the patients. Results The mean ± standard deviation dose (n = 165 patients) of Minirin parenteral administered was 0.37 ± 0.02 μg/kg b.w., most often upcoming dental operations (57%) necessitated testing. Coagulation parameters of patients with VWD 1 or TCP normalised in almost all patients, but only in approximately 50% of patients with VWD 2 respectively. Appraisal of effectiveness of Minirin parenteral as good was 96% in case of VWD 1 and 95 % in case of TCP. During minor surgeries (n = 23) in 91% of the patients no complications and in 2 patients (9%) postoperative haemorrhages without need for further interventions occurred, but 83% of the patients reported adverse reactions in the questionnaires, although Minirin parenteral was well tolerated by all patients during DDAVP efficacy tests. Conclusion Desmopressin is well tolerated and affective in patients with VWD 1 and thrombocytopathy.

scholarly journals A new method to study in vivo protein synthesis in slow- and fast-twitch muscle fibers and initial measurements in humans

2010 ◽  
Vol 108 (5) ◽  
pp. 1410-1416 ◽  
Author(s):  
J. M. Dickinson ◽  
J. D. Lee ◽  
B. E. Sullivan ◽  
M. P. Harber ◽  
S. W. Trappe ◽  
...  
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Human Muscle ◽  
Synthesis Rate ◽  
Mhc I ◽  
Fast Twitch ◽  
Mixed Protein ◽  
Mhc Iia

The aim of this study was to develop an approach to directly assess protein fractional synthesis rate (FSR) in isolated human muscle fibers in a fiber type-specific fashion. Individual muscle fibers were isolated from biopsies of the vastus lateralis (VL) and soleus (SOL) obtained from eight young men during a primed, continuous infusion of [5,5,5-2H3]leucine performed under basal conditions. To determine mixed protein FSR, a portion of each fiber was used to identify fiber type, fibers of the same type were pooled, and the [5,5,5-2H3]leucine enrichment was determined via GC-MS. Processing isolated slow-twitch [myosin heavy chain (MHC) I] and fast-twitch (MHC IIa) fibers for mixed protein bound [5,5,5-2H3]leucine enrichment yielded mass ion chromatographic peaks that were similar in shape, abundance, and measurement reliability as tissue homogenates. In the VL, MHC I fibers exhibited a 33% faster ( P < 0.05) mixed protein FSR compared with MHC IIa fibers (0.068 ± 0.006 vs. 0.051 ± 0.003%/h). MHC I fibers from the SOL (0.060 ± 0.005%/h) and MHC I fibers from the VL displayed similar ( P > 0.05) mixed protein FSR. Feasibility of processing isolated human muscle fibers for analysis of myofibrillar protein [5,5,5-2H3]leucine enrichment was also confirmed in non-fiber-typed pooled fibers from the VL. These methods can be applied to the study of fiber type-specific responses in human skeletal muscle. The need for this level of investigation is underscored by the different contributions of each fiber type to whole muscle function and the numerous distinct adaptive functional and metabolic changes in MHC I and MHC II fibers originating from the same muscle.

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