scholarly journals Human skeletal muscle: Phasic type of electrical stimulation increases its contractile speed

1990 ◽  
Vol 18 (6) ◽  
pp. 711-711
Author(s):  
R. Karba ◽  
A. Stefanovska ◽  
S. Dordević
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Human Skeletal Muscle ◽  
Phasic Type

Human skeletal muscle: Phasic type of electrical stimulation increases its contractile speed

1990 ◽  
Vol 18 (5) ◽  
pp. 479-490 ◽  
Author(s):  
Renata Karba ◽  
Aneta Stefanovska ◽  
Srđan Đorđević
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Human Skeletal Muscle ◽  
Phasic Type

scholarly journals Electrical stimulation increases hypertrophy and metabolic flux in tissue-engineered human skeletal muscle

Biomaterials ◽  
2019 ◽  
Vol 198 ◽  
pp. 259-269 ◽  
Author(s):  
Alastair Khodabukus ◽  
Lauran Madden ◽  
Neel K. Prabhu ◽  
Timothy R. Koves ◽  
Christopher P. Jackman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Human Skeletal Muscle ◽  
Metabolic Flux

Phosphorylase a in human skeletal muscle during exercise and electrical stimulation

1978 ◽  
Vol 45 (6) ◽  
pp. 852-857 ◽  
Author(s):  
P. D. Gollnick ◽  
J. Karlsson ◽  
K. Piehl ◽  
B. Saltin
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Muscular Activity ◽  
Voluntary Exercise ◽  
Vastus Lateralis Muscle ◽  
Minor Importance ◽  
Muscle Lactate ◽  
Needle Technique

Experiments were conducted to examine the conversions of phosphorylase b to phosphorylase a in human skeletal muscle during bicycle exercise or isometric contractions. Muscle biopsies were obtained from the vastus lateralis with the needle technique at rest and either during or immediately after activity and frozen in liquid nitrogen within 2--4 s. Total phosphorylase and phosphorylase a activities were differentiated by measurement in the presence and absence of AMP, respectively. At rest 8.5% of the total phosphorylase activity existed in the a form. Little or no change in the percent of phosphorylase in the a form occurred during voluntary dynamic or static muscular activity that produced muscle lactate concentrations in excess of 18 mmol.kg-1 wet muscle. Electrical stimulation of the vastus lateralis muscle also failed to produce an increase in the percentage of phosphorylase a. These data suggest that during exercise the conversion of phosphorylase to the a form is of minor importance. An increased activity of phosphorylase b due to changes in muscle concentrations of ATP, AMP, and inorganic phosphate may regulate glycogenolysis during voluntary exercise in man.

Neuromuscular electrical stimulation training induces atypical adaptations of the human skeletal muscle phenotype: a functional and proteomic analysis

2011 ◽  
Vol 110 (2) ◽  
pp. 433-450 ◽  
Author(s):  
Julien Gondin ◽  
Lorenza Brocca ◽  
Elena Bellinzona ◽  
Giuseppe D'Antona ◽  
Nicola A. Maffiuletti ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Proteomic Analysis ◽  
Metabolic Profile ◽  
Human Skeletal Muscle ◽  
Protein Pattern ◽  
Neuromuscular Electrical Stimulation ◽  
Vastus Lateralis Muscle ◽  
Before And After ◽  
Antioxidant Defense Systems

The aim of the present study was to define the chronic effects of neuromuscular electrical stimulation (NMES) on the neuromuscular properties of human skeletal muscle. Eight young healthy male subjects were subjected to 25 sessions of isometric NMES of the quadriceps muscle over an 8-wk period. Needle biopsies were taken from the vastus lateralis muscle before and after training. The training status, myosin heavy chain (MHC) isoform distribution, and global protein pattern, as assessed by proteomic analysis, widely varied among subjects at baseline and prompted the identification of two subgroups: an “active” (ACT) group, which performed regular exercise and had a slower MHC profile, and a sedentary (SED) group, which did not perform any exercise and had a faster MHC profile. Maximum voluntary force and neural activation significantly increased after NMES in both groups (+∼30% and +∼10%, respectively). Both type 1 and 2 fibers showed significant muscle hypertrophy. After NMES, both groups showed a significant shift from MHC-2X toward MHC-2A and MHC-1, i.e., a fast-to-slow transition. Proteomic maps showing ∼500 spots were obtained before and after training in both groups. Differentially expressed proteins were identified and grouped into functional categories. The most relevant changes regarded 1) myofibrillar proteins, whose changes were consistent with a fast-to-slow phenotype shift and with a strengthening of the cytoskeleton; 2) energy production systems, whose changes indicated a glycolytic-to-oxidative shift in the metabolic profile; and 3) antioxidant defense systems, whose changes indicated an enhancement of intracellular defenses against reactive oxygen species. The adaptations in the protein pattern of the ACT and SED groups were different but were, in both groups, typical of both resistance (i.e., strength gains and hypertrophy) and endurance (i.e., a fast-to-slow shift in MHC and metabolic profile) training. These training-induced adaptations can be ascribed to the peculiar motor unit recruitment pattern associated with NMES.

pH measurement in human skeletal muscle samples: effect of phosphagen hydrolysis

1986 ◽  
Vol 61 (5) ◽  
pp. 1949-1954 ◽  
Author(s):  
L. L. Spriet ◽  
K. Soderlund ◽  
J. A. Thomson ◽  
E. Hultman
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Intracellular Ph ◽  
Human Skeletal Muscle ◽  
Practical Method ◽  
Human Muscle ◽  
Ph Measurement ◽  
Muscle Ph

Measurements of muscle pH (pHm) with the homogenate technique are routinely made when extensive phosphagen hydrolysis has occurred. Upon exposure of the homogenate to 37 degrees C in the pH meter, phosphocreatine and ATP were rapidly degraded to 35 and 60% of control concentrations after 30 s. Attempts at chemically arresting this hydrolysis were unsuccessful. Therefore we examined the significance of phosphagen hydrolysis on pHm measurement in human biopsies taken at rest and following intense electrical stimulation. To accomplish this, pHm was measured at 0 degree C, where extensive hydrolysis did not occur. On the same homogenate, pHm was measured at 0 degree C with phosphagens and at 0 and 37 degrees C after phosphagen hydrolysis. The effect of phosphagen hydrolysis on pHm at 0 degrees C was used to estimate this effect at 37 degrees C. In resting samples, phosphagen hydrolysis produced a nonsignificant acidification of 0.008 pH units and, in electrically stimulated samples, a nonsignificant alkalinization of 0.033 units. Measurements of homogenate PCO2 suggested that most of the CO2 remained in the sample during pHm measurement at 37 degrees C. The present work substantiates the use of the homogenate technique as an accurate and practical method for the estimation of intracellular pH in resting and exercise human muscle samples.

Human skeletal muscle adaptation in response to chronic low-frequency electrical stimulation

1994 ◽  
Vol 77 (4) ◽  
pp. 1885-1889 ◽  
Author(s):  
R. Theriault ◽  
G. Theriault ◽  
J. A. Simoneau
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Human Skeletal Muscle ◽  
Citrate Synthase ◽  
Low Frequency ◽  
Vastus Lateralis Muscle ◽  
Activity Levels ◽  
Hydroxyacyl Coa Dehydrogenase

The purpose of the study was to verify the influence of several weeks of chronic low-frequency electrical stimulation (LFES) on the metabolic profile and functional capacity of human skeletal muscle. Knee extensor muscles (KEM) of eight subjects were electrically stimulated at 8 Hz for 8 h/day and 6 days/wk. Vastus lateralis muscle samples were taken before, after 4 wk, and after 8 wk of LFES, and activities of anaerobic (creatine kinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase) and aerobic-oxidative (citrate synthase, 3-hydroxyacyl-CoA dehydrogenase, cytochrome-c oxidase) enzyme markers were determined. KEM dynamic performance was also assessed before, after 4 wk, and after 8 wk of LFES. Activity levels of anaerobic enzymes were not altered, whereas the activity levels of citrate synthase (29%),3-hydroxyacyl-CoA dehydrogenase (22%), and cytochrome-c oxidase (25%) were significantly increased after 4 wk of LFES but were not further increased after 4 additional wk of LFES. KEM performance was also improved (P < 0.05) but leveled off after 4 wk of LFES. Although significant changes were observed, the results of the present study suggest that the muscle characteristics investigated in the current study have a limited capacity of adaptation in response to this form of chronic LFES.

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