Single muscle fiber function with concurrent exercise or nutrition countermeasures during 60 days of bed rest in women

2007 ◽  
Vol 103 (4) ◽  
pp. 1242-1250 ◽  
Author(s):  
Scott Trappe ◽  
Andrew Creer ◽  
Dustin Slivka ◽  
Kiril Minchev ◽  
Todd Trappe
Keyword(s):  
Skeletal Muscle ◽  
Contractile Function ◽  
Vastus Lateralis ◽  
Bed Rest ◽  
Vastus Lateralis Muscle ◽  
Single Muscle ◽  
Mhc I ◽  
Lateralis Muscle ◽  
Concurrent Exercise ◽  
And Function

There is limited information on skeletal muscle properties in women with unloading and countermeasure programs to protect the unloading-induced atrophy. The current investigation tested the hypothesis that a concurrent aerobic and resistance exercise training program would preserve size and contractile function of slow- and fast-twitch muscle fibers. A secondary objective was to test the hypothesis that a leucine-enriched high-protein diet would partially attenuate single fiber characteristics. Vastus lateralis muscle biopsies were obtained before and on day 59 of bed rest from a control (BR; n = 8), nutrition (BRN; n = 8), or exercise (BRE; n = 8) group. Single muscle fibers were studied for diameter, peak force (Po), contractile velocity, and power. Those in the BR group had a decrease ( P < 0.05) in myosin heavy chain (MHC) I diameter (−14%), Po (−35%), and power (−42%) and MHC IIa diameter (−16%) and Po (−31%; P = 0.06) and an increase ( P < 0.05) in MHC hybrid fibers. Changes in size and function of MHC I (−19 to −44%) and IIa (−21% to −30%) fibers and MHC distribution in BRN individuals were similar to results in the BR group. In BRE conditions, MHC I and IIa size and contractile function were preserved during bed rest. These data show that the concurrent exercise program preserved the myocellular profile of the vastus lateralis muscle during 60-day bed rest. To combat muscle atrophy and function with long-term unloading, the exercise prescription program used in this study should be considered as a viable training program for the upper leg muscles, whereas the nutritional intervention used cannot be recommended as a countermeasure for skeletal muscle.

scholarly journals Effects of weight loss and leptin on skeletal muscle in human subjects

2011 ◽  
Vol 301 (5) ◽  
pp. R1259-R1266 ◽  
Author(s):  
Kenneth M. Baldwin ◽  
Denis R. Joanisse ◽  
Fadia Haddad ◽  
Rochelle L. Goldsmith ◽  
Dympna Gallagher ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Weight Loss ◽  
Body Weight ◽  
Human Subjects ◽  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
Work Efficiency ◽  
Mhc I ◽  
Reduced Body ◽  
Lateralis Muscle

Maintenance of a 10% or greater reduced body weight results in decreases in the energy cost of low levels of physical activity beyond those attributable to the altered body weight. These changes in nonresting energy expenditure are due mainly to increased skeletal muscle work efficiency following weight loss and are reversed by the administration of the adipocyte-derived hormone leptin. We have also shown previously that the maintenance of a reduced weight is accompanied by a decrease in ratio of glycolytic (phosphofructokinase) to oxidative (cytochrome c oxidase) activity in vastus lateralis muscle that would suggest an increase in the relative expression of the myosin heavy chain I (MHC I) isoform. We performed analyses of vastus lateralis muscle needle biopsy samples to determine whether maintenance of an altered body weight was associated with changes in skeletal muscle metabolic properties as well as mRNA expression of different isoforms of the MHC and sarcoplasmic endoplasmic reticular Ca2+-dependent ATPase (SERCA) in subjects studied before weight loss and then again after losing 10% of their initial weight and receiving twice daily injections of either placebo or replacement leptin in a single blind crossover design. We found that the maintenance of a reduced body weight was associated with significant increases in the relative gene expression of MHC I mRNA that was reversed by the administration of leptin as well as an increase in the expression of SERCA2 that was not significantly affected by leptin. Leptin administration also resulted in a significant increase in the expression of the less MHC IIx isoform compared with subjects receiving placebo. These findings are consistent with the leptin-reversible increase in skeletal muscle chemomechanical work efficiency and decrease in the ratio of glycolytic/oxidative enzyme activities observed in subjects following dietary weight loss.

Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest

2008 ◽  
Vol 294 (3) ◽  
pp. R939-R947 ◽  
Author(s):  
Scott Trappe ◽  
Andrew Creer ◽  
Kiril Minchev ◽  
Dustin Slivka ◽  
Emily Louis ◽  
...  
Keyword(s):  
Muscle Fiber ◽  
Soleus Muscle ◽  
Contractile Function ◽  
Exercise Program ◽  
Bed Rest ◽  
Single Fiber ◽  
Single Muscle ◽  
Mhc I ◽  
Single Muscle Fiber ◽  
Concurrent Exercise

The soleus muscle has been consistently shown to atrophy more than other leg muscles during unloading and is difficult to protect using various exercise countermeasure paradigms. However, the efficacy of aerobic exercise, a known stimulus for oxidative adaptations, has not been tested in combination with resistance exercise (RE), a known hypertrophic stimulus. We hypothesized that a concurrent exercise program (AE + RE) would preserve soleus fiber myosin heavy chain (MHC) I size and function during 60 days of bed rest. A secondary objective was to test the hypothesis that a leucine-enriched high protein diet would partially protect soleus single fiber characteristics. Soleus muscle biopsies were obtained before and after bed rest from a control (BR; n = 7), nutrition (BRN; n = 8), and exercise (BRE; n = 6) group. Single muscle fiber diameter (Dia), peak force (Po), contractile velocity, and power were studied. BR decreased ( P < 0.05) MHC I Dia (−14%), Po (−38%), and power (−39%) with no change in contractile velocity. Changes in MHC I size (−13%) and contractile function (∼30%) from BRN were similar to BR. BRE decreased ( P < 0.05) MHC I Dia (−13%) and Po (−23%), while contractile velocity increased ( P < 0.05) 26% and maintained power. These soleus muscle data show 1) the AE + RE exercise program maintained MHC I power but not size and strength, and 2) the nutrition countermeasure did not benefit single fiber size and contractile function. The divergent response in size and functional MHC I soleus properties with the concurrent exercise program was a unique finding further highlighting the challenges of protecting the unloaded soleus.

scholarly journals Sympathoexcitation constrains vasodilation in the human skeletal muscle microvasculature during postocclusive reactive hyperemia

2018 ◽  
Vol 315 (2) ◽  
pp. H242-H253 ◽  
Author(s):  
Masashi Ichinose ◽  
Mikie Nakabayashi ◽  
Yumie Ono
Keyword(s):  
Skeletal Muscle ◽  
Vastus Lateralis ◽  
Reactive Hyperemia ◽  
Correlation Spectroscopy ◽  
Flow Index ◽  
Vastus Lateralis Muscle ◽  
Diffuse Correlation Spectroscopy ◽  
Sympathetic Vasoconstriction ◽  
Lateralis Muscle ◽  
Postocclusive Reactive Hyperemia

We used diffuse correlation spectroscopy to investigate sympathetic vasoconstriction, local vasodilation, and integration of these two responses in the skeletal muscle microvasculature of 20 healthy volunteers. Diffuse correlation spectroscopy probes were placed on the flexor carpi radialis muscle or vastus lateralis muscle, and a blood flow index was derived continuously. We measured hemodynamic responses during sympathoexcitation induced by forehead cooling, after which the effects of the increased sympathetic tone on vasodilatory responses during postocclusive reactive hyperemia (PORH) were examined. PORH was induced by releasing arterial occlusion (3 min) in an arm or leg. To increase sympathetic tone during PORH, forehead cooling was begun 60 s before the occlusion release and ended 60 s after the release. During forehead cooling, mean arterial pressure rose significantly and was sustained at an elevated level. Significant vasoconstriction and decreases in blood flow index followed by gradual blunting of the vasoconstriction also occurred. The time course of these responses is in good agreement with previous observations in animals. The acute sympathoexcitation diminished the peak vasodilation during PORH only in the vastus lateralis muscle, but it hastened the decline in vasodilation after the peak in both the flexor carpi radialis muscle and vastus lateralis muscle. Consequently, the total vasodilatory response assessed as the area of the vascular conductance during the first minute of PORH was significantly diminished in both regions. We conclude that, in humans, the integrated effects of sympathetic vasoconstriction and local vasodilation have an important role in vascular regulation and control of perfusion in the skeletal muscle microcirculation. NEW & NOTEWORTHY We used diffuse correlation spectroscopy to demonstrate that acute sympathoexcitation constrains local vasodilation in the human skeletal muscle microvasculature during postocclusive reactive hyperemia. This finding indicates that integration of sympathetic vasoconstriction and local vasodilation is importantly involved in vascular regulation and the control of perfusion of the skeletal muscle microcirculation in humans.

Effects of Ultratrail Running on Skeletal-Muscle Oxygenation Dynamics

2017 ◽  
Vol 12 (4) ◽  
pp. 496-504 ◽  
Author(s):  
Gianluca Vernillo ◽  
Alfredo Brighenti ◽  
Eloisa Limonta ◽  
Pietro Trabucchi ◽  
Davide Malatesta ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Vastus Lateralis ◽  
Oxygenation Index ◽  
Constant Load ◽  
Negative Influence ◽  
Muscle Oxygenation ◽  
Vastus Lateralis Muscle ◽  
Skeletal Muscle Oxygenation ◽  
Power Outputs ◽  
And Function

Purpose:To quantify changes in skeletal-muscle oxygenation and pulmonary O2 uptake (V̇O2) after an extreme ultratrail running bout.Methods:Before (PRE) and after (POST) the race (330-km, 24000 D±), profiles of vastus lateralis muscle oxygenation (ie, oxyhemoglobin [O2Hb], deoxyhemoglobin [HHb], and tissue oxygenation index [TOI]) and V̇O2 were determined in 14 athletes (EXP) and 12 control adults (CON) during two 4-min constant-load cycling bouts at power outputs of 1 (p1) and 1.5 (p1.5) W/kg performed in randomized order.Results:At POST, normalized [HHb] values increased (p1, +38.0%; p1.5, +27.9%; P < .05), while normalized [O2Hb] (p1, –20.4%; p1.5, –14.4%; P < .05) and TOI (p1, –17.0%; p1.5, –17.7%; P < .05) decreased in EXP. V̇O2 values were similar (P > 0.05). An “overshoot“ in normalized [HHb]:V̇O2 was observed, although the increase was significant only during p1.5 (+58.7%, P = .003). No difference in the aforementioned variables was noted in CON (P > .05).Conclusions:The concentric and, particularly, the eccentric loads characterizing this extreme ultratrail-running bout may have led to variations in muscle structure and function, increasing the local muscle deoxygenation profile and the imbalance between O2 delivery to working muscles and muscle O2 consumption. This highlights the importance of incorporating graded training, particularly downhill bouts, to reduce the negative influence of concentric and severe eccentric loads to the microcirculatory function and to enhance the ability of runners to sustain such loading.

scholarly journals Skeletal muscle phosphatidylcholine and phosphatidylethanolamine are related to insulin sensitivity and respond to acute exercise in humans

2016 ◽  
Vol 120 (11) ◽  
pp. 1355-1363 ◽  
Author(s):  
Sean A. Newsom ◽  
Joseph T. Brozinick ◽  
Katja Kiseljak-Vassiliades ◽  
Allison N. Strauss ◽  
Samantha D. Bacon ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Acute Exercise ◽  
Contractile Function ◽  
Vastus Lateralis ◽  
Mass Spectrometry Analysis ◽  
Vastus Lateralis Muscle ◽  
Intravenous Glucose ◽  
Exercise In Humans

Several recent reports indicate that the balance of skeletal muscle phosphatidylcholine (PC) and phosphatidylethanolamine (PE) is a key determinant of muscle contractile function and metabolism. The purpose of this study was to determine relationships between skeletal muscle PC, PE and insulin sensitivity, and whether PC and PE are dynamically regulated in response to acute exercise in humans. Insulin sensitivity was measured via intravenous glucose tolerance in sedentary obese adults (OB; n = 14), individuals with type 2 diabetes (T2D; n = 15), and endurance-trained athletes (ATH; n = 15). Vastus lateralis muscle biopsies were obtained at rest, immediately after 90 min of cycle ergometry at 50% maximal oxygen consumption (V̇o2 max), and 2-h postexercise (recovery). Skeletal muscle PC and PE were measured via infusion-based mass spectrometry/mass spectrometry analysis. ATH had greater levels of muscle PC and PE compared with OB and T2D ( P < 0.05), with total PC and PE positively relating to insulin sensitivity (both P < 0.05). Skeletal muscle PC:PE ratio was elevated in T2D compared with OB and ATH ( P < 0.05), tended to be elevated in OB vs. ATH ( P = 0.07), and was inversely related to insulin sensitivity among the entire cohort ( r = −0.43, P = 0.01). Muscle PC and PE were altered by exercise, particularly after 2 h of recovery, in a highly group-specific manner. However, muscle PC:PE ratio remained unchanged in all groups. In summary, total muscle PC and PE are positively related to insulin sensitivity while PC:PE ratio is inversely related to insulin sensitivity in humans. A single session of exercise significantly alters skeletal muscle PC and PE levels, but not PC:PE ratio.

scholarly journals Human vastus lateralis and soleus muscles display divergent cellular contractile properties

2008 ◽  
Vol 295 (5) ◽  
pp. R1593-R1598 ◽  
Author(s):  
Nicholas Luden ◽  
Kiril Minchev ◽  
Erik Hayes ◽  
Emily Louis ◽  
Todd Trappe ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Contractile Function ◽  
Vastus Lateralis ◽  
Single Fiber ◽  
Muscle Adaptation ◽  
Shortening Velocity ◽  
Mhc I ◽  
Myosin Heavy Chain Isoform ◽  
I 18 ◽  
Mhc Iia

The purpose of this study was to investigate potential differences in single-fiber contractile physiology of fibers with the same myosin heavy chain isoform (MHC I and MHC IIa) originating from different muscles. Vastus lateralis (VL) and soleus biopsies were obtained from 27 recreationally active females (31 ± 1 yr, 59 ± 1 kg). A total of 943 single fibers (MHC I = 562; MHC IIa = 301) were isolated and examined for diameter, peak tension (Po), shortening velocity (Vo), and power. The soleus had larger ( P < 0.05) fibers (MHC I +18%; MHC IIa +19%), higher MHC I Vo (+13%), and higher MHC I Po (+18%) compared with fibers from the VL. In contrast, fibers from the VL had higher ( P < 0.05) specific tension (MHC I +18%; MHC IIa +20%), and MHC I normalized power (+25%) compared with the soleus. There was a trend for MHC IIa soleus fibers to have higher Vo [MHC IIa +13% ( P = 0.058)], whereas VL MHC IIa fibers showed a trend for higher normalized power compared with soleus fibers [MHC IIa +33% ( P = 0.079)]. No differences in absolute power were detected between muscles. These data highlight muscle-specific differences in single-fiber contractile function that should serve as a scientific basis for consideration when extending observations of skeletal muscle tissue from one muscle of interest to other muscles of origin. This is important when examining skeletal muscle adaptation to physical states such as aging, unloading, and training.

scholarly journals Effect of Eccentric and Concentric Contraction Mode on Myogenic Regulatory Factors Expression in Human Vastus Lateralis Muscle

2021 ◽  
Author(s):  
Mostafa Sabouri ◽  
Pejman Taghibeikzadehbadr ◽  
Fatemeh Shabkhiz ◽  
Zahra Izanloo ◽  
Farahnaz Amir Shaghaghi
Keyword(s):  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
Myogenic Regulatory Factors ◽  
Mhc I ◽  
Regulatory Factors ◽  
Isokinetic Contraction ◽  
Concentric Contraction ◽  
Significant Difference ◽  
Lateralis Muscle ◽  
Mhc Iia

Abstract Background: Skeletal muscle contractions are caused to release myokines by muscle fiber. This study investigated the myogenic regulatory factors, as MHC I, IIA, IIX, Myo-D, MRF4, Murf, Atrogin-1, Decorin, Myonection, and IL-15 mRNA expression in the response of eccentric vs. concentric contraction. Methods: Eighteen healthy men were randomly divided into two eccentric and concentric groups, each of 9 persons. Isokinetic contraction protocols included maximal single-leg eccentric or concentric knee extension tasks at 60°/s with the dominant leg. Contractions consisted of a maximum of 12 sets of 10 reps, and the rest time between each set was 30 seconds. The baseline biopsy was performed four weeks before the study, and post-test biopsies were taken immediately after exercise protocols from Vastus Lateralis muscle. The gene expression levels evaluated using Real-Time PCR methods. Results: A significant difference in MyoD, MRF4, Myonection, and Decorin mRNA, were observed following eccentric or concentric contractions (P≤0.05). The MHC I, MHC IIA, IL-15 mRNA has been changed significantly compared to the pre-exercise in the concentric group (P≤0.05). While only MHC IIX and Atrogin-1 mRNA changed significantly in the eccentric group (P≤0.05). Additionally, the results showed a significant difference in MyoD, MRF4, IL-15, and Decorin were observed at the follow-up values between eccentric or concentric groups (P≤0.05). Conclusion: Our findings highlight the growing importance of elucidating the different responses of muscle growth factors associated with a myogenic activity such as MHC IIA, Decorin, IL-15, Myonectin, Decorin, MuRF1, and MHC IIX mRNA in following to various types of exercise.

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.

scholarly journals History-dependence of muscle slack length in humans: effects of contraction intensity, stretch amplitude, and time

2020 ◽  
Vol 129 (4) ◽  
pp. 957-966
Author(s):  
Martin Eric Héroux ◽  
Ida Anderman ◽  
Sofia Nykvist Vouis ◽  
Joanna Diong ◽  
Peter William Stubbs ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Large Amplitude ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
History Dependence ◽  
Lateralis Muscle ◽  
Slack Length ◽  
Passive Stretch

The slack length of a relaxed human skeletal muscle is not fixed; it can be modified by contraction and stretch. Contraction of the human vastus lateralis muscle at short lengths reduces the muscle’s slack length. Even very weak contractions are sufficient to induce this effect. The effect persists for at least 5 min but can be reduced or abolished with a large-amplitude passive stretch.

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