scholarly journals Metabolic adaptations in skeletal muscle after 84 days of bed rest with and without concurrent flywheel resistance exercise

2017 ◽  
Vol 122 (1) ◽  
pp. 96-103 ◽  
Author(s):  
José M. Irimia ◽  
Mario Guerrero ◽  
Paula Rodriguez-Miguelez ◽  
Joan A. Cadefau ◽  
Per A. Tesch ◽  
...  

As metabolic changes in human skeletal muscle after long-term (simulated) spaceflight are not well understood, this study examined the effects of long-term microgravity, with and without concurrent resistance exercise, on skeletal muscle oxidative and glycolytic capacity. Twenty-one men were subjected to 84 days head-down tilt bed rest with (BRE; n = 9) or without (BR; n = 12) concurrent flywheel resistance exercise. Activity and gene expression of glycogen synthase, glycogen phosphorylase (GPh), hexokinase, phosphofructokinase-1 (PFK-1), and citrate synthase (CS), as well as gene expression of succinate dehydrogenase (SDH), vascular endothelial growth factor (VEFG), peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1α), and myostatin, were analyzed in samples from m. vastus lateralis collected before and after bed rest. Activity and gene expression of enzymes controlling oxidative metabolism (CS, SDH) decreased in BR but were partially maintained in BRE. Activity of enzymes regulating anaerobic glycolysis (GPh, PFK-1) was unchanged in BR. Resistance exercise increased the activity of GPh. PGC-1α and VEGF expression decreased in both BR and BRE. Myostatin increased in BR but decreased in BRE after bed rest. The analyses of these unique samples indicate that long-term microgravity induces marked alterations in the oxidative, but not the glycolytic, energy system. The proposed flywheel resistance exercise was effective in counteracting some of the metabolic alterations triggered by 84-day bed rest. Given the disparity between gene expression vs. enzyme activity in several key metabolic markers, posttranscriptional mechanisms should be explored to fully evaluate metabolic adaptations to long-term microgravity with/without exercise countermeasures in human skeletal muscle.

2019 ◽  
Vol 44 (12) ◽  
pp. 1391-1394
Author(s):  
Martin J. MacInnis ◽  
Lauren E. Skelly ◽  
F. Elizabeth Godkin ◽  
Brian J. Martin ◽  
Thomas R. Tripp ◽  
...  

The legs of 9 men (age 21 ± 2 years, 45 ± 4 mL/(kg·min)) were randomly assigned to complete 6 sessions of high-intensity exercise training, involving either one or four 5-min bouts of counterweighted, single-leg cycling. Needle biopsies from vastus lateralis revealed that citrate synthase maximal activity increased after training in the 4-bout group (p = 0.035) but not the 1-bout group (p = 0.10), with a significant difference between groups post-training (13%, p = 0.021). Novelty Short-term training using brief intense exercise requires multiple bouts per session to increase mitochondrial content in human skeletal muscle.


2005 ◽  
Vol 99 (3) ◽  
pp. 950-956 ◽  
Author(s):  
Andrew Creer ◽  
Philip Gallagher ◽  
Dustin Slivka ◽  
Bozena Jemiolo ◽  
William Fink ◽  
...  

Two pathways that have been implicated for cellular growth and development in response to muscle contraction are the extracellular signal-regulated kinase (ERK1/2) and Akt signaling pathways. Although these pathways are readily stimulated after exercise, little is known about how nutritional status may affect stimulation of these pathways in response to resistance exercise in human skeletal muscle. To investigate this, experienced cyclists performed 30 repetitions of knee extension exercise at 70% of one repetition maximum after a low (2%) or high (77%) carbohydrate (LCHO or HCHO) diet, which resulted in low or high (∼174 or ∼591 mmol/kg dry wt) preexercise muscle glycogen content. Muscle biopsies were taken from the vastus lateralis before, ∼20 s after, and 10 min after exercise. ERK1/2 and p90 ribosomal S6 kinase phosphorylation increased ( P ≤ 0.05) 10 min after exercise, regardless of muscle glycogen availability. Akt phosphorylation was elevated ( P < 0.05) 10 min after exercise in the HCHO trial but was unaffected after exercise in the LCHO trial. Mammalian target of rapamycin phosphorylation was similar to that of Akt during each trial; however, change or lack of change was not significant. In conclusion, the ERK1/2 pathway appears to be unaffected by muscle glycogen content. However, muscle glycogen availability appears to contribute to regulation of the Akt pathway, which may influence cellular growth and adaptation in response to resistance exercise in a low-glycogen state.


2009 ◽  
Vol 74 (11) ◽  
pp. 1239-1252 ◽  
Author(s):  
M. A. Kovalyova ◽  
L. I. Kovalyov ◽  
I. Yu. Toropygin ◽  
S. V. Shigeev ◽  
A. V. Ivanov ◽  
...  

2018 ◽  
Vol 124 (4) ◽  
pp. 1012-1024 ◽  
Author(s):  
Andrew C. D’Lugos ◽  
Shivam H. Patel ◽  
Jordan C. Ormsby ◽  
Donald P. Curtis ◽  
Christopher S. Fry ◽  
...  

Resistance exercise (RE) is a powerful stimulus for skeletal muscle adaptation. Previous data demonstrate that cyclooxygenase (COX)-inhibiting drugs alter the cellular mechanisms regulating the adaptive response of skeletal muscle. The purpose of this study was to determine whether prior consumption of the COX inhibitor acetaminophen (APAP) alters the immediate adaptive cellular response in human skeletal muscle after RE. In a double-blinded, randomized, crossover design, healthy young men ( n = 8, 25 ± 1 yr) performed two trials of unilateral knee extension RE (8 sets, 10 reps, 65% max strength). Subjects ingested either APAP (1,000 mg/6 h) or placebo (PLA) for 24 h before RE (final dose consumed immediately after RE). Muscle biopsies (vastus lateralis) were collected at rest and 1 h and 3 h after exercise. Mammalian target of rapamycin (mTOR) complex 1 signaling was assessed through immunoblot and immunohistochemistry, and mRNA expression of myogenic genes was examined via RT-qPCR. At 1 h p-rpS6Ser240/244 was increased in both groups but to a greater extent in PLA. At 3 h p-S6K1Thr389 was elevated only in PLA. Furthermore, localization of mTOR to the lysosome (LAMP2) in myosin heavy chain (MHC) II fibers increased 3 h after exercise only in PLA. mTOR-LAMP2 colocalization in MHC I fibers was greater in PLA vs. APAP 1 h after exercise. Myostatin mRNA expression was reduced 1 h after exercise only in PLA. MYF6 mRNA expression was increased 1 h and 3 h after exercise only in APAP. APAP consumption appears to alter the early adaptive cellular response of skeletal muscle to RE. These findings further highlight the mechanisms through which COX-inhibiting drugs impact the adaptive response of skeletal muscle to exercise. NEW & NOTEWORTHY The extent to which the cellular reaction to acetaminophen impacts the mechanisms regulating the adaptive response of human skeletal muscle to resistance exercise is not well understood. Consumption of acetaminophen before resistance exercise appears to suppress the early response of mTORC1 activity to acute resistance exercise. These data also demonstrate, for the first time, that resistance exercise elicits fiber type-specific changes in the intracellular colocalization of mTOR with the lysosome in human skeletal muscle.


1999 ◽  
Vol 86 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Yuefei Liu ◽  
Sabine Mayr ◽  
Alexandra Opitz-Gress ◽  
Claudia Zeller ◽  
Werner Lormes ◽  
...  

Previous studies have demonstrated exercise-induced heat shock protein 70 (HSP70) in animals. The purpose of this study was to investigate human skeletal muscle HSP70 response to rowing training. Ten male rowers trained for 4 wk with different forms, durations, and intensities of exercise. Biopsy was performed in the right musculus vastus lateralis before training and at the end of each week. HSP70 in 5 μg of total protein from the muscle sample was determined by using Western blot and immunodetection with chemiluminescence technique, by means of laser densitometer referring to a series of known standard HSP70. Compared with pretraining (100%), HSP70 increased during training (181, 405, 456, and 363% from the first to fourth training week, respectively) with the maximum HSP70 production at the end of second training week. Thus HSP70 is induced in highly trained human muscle by long-term training.


2021 ◽  
Vol 30 (1) ◽  
pp. 102-109
Author(s):  
Kyung-Wan Baek ◽  
Ji-Seok Kim ◽  
Jun-Il Yoo

PURPOSE: Recently, METTL21C has been identified as a potential pleiotropic gene for osteoporosis and sarcopenia. The purpose of this study was to collect gene expression datasets of human skeletal muscle transcriptome and to determine their relationship to exercise through meta-analysis.METHODS: MetaMEx was used to determine whether METTL21C in human skeletal muscle was associated with age, sex, physical activity and obesity. In addition, the difference in gene expression of METTL21C according to exercise duration and exercise type was confirmed. Using MetaMEx, top 300 genes (positive and negative, respectively) with a high correlation with METTL21C were selected, and gene ontology analysis was performed to identify related pathways.RESULTS:The expression of METTL21C gene in human skeletal muscle was significantly lower in the elderly than in young subjects (p<.0001), and significantly lower in female than in male (p<.0001). Also, the obese subjects were significantly lower than lean subjects (p<.0001). However, subjects with high level of physical activity had significantly higher expression of METTL21C than subjects with low levels of physical activity (p<.0001). Acute resistance exercise (p<.0001) and acute high-intensity interval training (p<.05) were found to have significantly higher expression of METTL21C in the skeletal muscle of the exercise group compared to the control group. Aerobic exercise training (p<.0001) and resistance exercise training (p<.0001) showed significantly higher expression of METTL21C in the skeletal muscle of the exercise group compared to the control group.CONCLUSIONS: Physical activity and exercise is important to prevent and treat osteosarcopenia because it can increase the expression of METTL21C in human skeletal muscle and maintain bone and muscle homeostasis.


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