Effects of ischaemic training on force development and fibre-type composition in human skeletal muscle

1. A new method of studying isolated human skeletal muscle has been evaluated. This involves the incubation and electrical stimulation of strips of muscle, obtained at surgical biopsy, that are tied at the cut ends of the fibre bundles. 2. Morphological examination showed that the fibres were sealed off at the cut ends. Damage appeared to be restricted to the areas immediately adjacent to the ties. 3. Contractile properties were well maintained for several hours and measurements of tissue metabolites showed that muscle contents of the high-energy phosphate compounds were well preserved. 4. The isolated preparations were found to have the same contractile properties as human quadriceps femoris studied in vivo by the methods described in the preceding paper. 5. Correlation was found between the relaxation speed of the isolated preparations and their fibre-type composition histochemically determined. 6. It is concluded that this technique is a valid addition to the present methods of studying the physiology and pharmacology of human skeletal muscle.

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Acute upregulation of PGC-1α mRNA correlates with training-induced increases in SDH activity in human skeletal muscle

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2016-0463 ◽

2017 ◽

Vol 42 (6) ◽

pp. 656-666 ◽

Cited By ~ 6

Author(s):

Jacob T. Bonafiglia ◽

Brittany A. Edgett ◽

Brittany L. Baechler ◽

Matthew W. Nelms ◽

Craig A. Simpson ◽

...

Keyword(s):

Skeletal Muscle ◽

Mrna Expression ◽

Human Skeletal Muscle ◽

Interval Training ◽

Capillary Density ◽

Oxidative Capacity ◽

Peak Oxygen Uptake ◽

Fibre Type Composition ◽

Type Composition ◽

Acute Responses

The purpose of the present study was to determine if acute responses in PGC-1α, VEGFA, SDHA, and GPD1–2 mRNA expression predict their associated chronic skeletal muscle molecular (SDH–GPD activity and substrate storage) and morphological (fibre-type composition and capillary density) adaptations following training. Skeletal muscle biopsies were collected from 14 recreationally active men (age: 22.0 ± 2.4 years) before (PRE) and 3 h after (3HR) the completion of an acute bout of sprint interval training (SIT) (eight 20-s intervals at ∼170% peak oxygen uptake work rate separated by 10 s of recovery). Participants then completed 6 weeks of SIT 4 times per week with additional biopsies after 2 (MID) and 6 (POST) weeks of training. Acute increases in PGC-1α mRNA strongly predicted increases in SDH activity (a marker of oxidative capacity) from PRE and MID to POST (PRE–POST: r = 0.81, r2 = 0.65, p < 0.01; MID–POST: r = 0.79, r2 = 0.62, p < 0.01) and glycogen content from MID to POST (r = 0.60, r2 = 0.36, p < 0.05). No other significant relationships were found between acute responses in PGC-1α, VEGFA, SDHA, and GPD1–2 mRNA expression and chronic adaptations to training. These results suggest that acute upregulation of PGC-1α mRNA relates to the magnitude of subsequent training-induced increases in oxidative capacity, but not other molecular and morphological chronic skeletal muscle adaptations. Additionally, acute mRNA responses in PGC-1α correlated with VEGFA, but not SDHA, suggesting a coordinated upregulation between PGC-1α and only some of its proposed targets in human skeletal muscle.

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