Daily blood flow restriction does not affect muscle fiber capillarization & satellite cell content during […] bed rest in healthy young men, 2024

Daily blood flow restriction does not affect muscle fiber capillarization and satellite cell content during two weeks of bed rest in healthy young men
Thorben Aussieker; Cas J. Fuchs; Antoine Zorenc; Lex B. Verdijk; Luc J.C. van Loon; Tim Snijders

The present study assessed whether single-leg daily blood flow restriction (BFR) treatment attenuates the decline in muscle fiber size, capillarization, and satellite cell (SC) content during 2 weeks of bed rest in healthy, young men.

Twelve healthy, young men (age: 24±3 y; BMI: 23.7±3.1 kg/m2) were subjected to 2 weeks of bed rest, during which one leg was exposed to three times daily 5 min of BFR, whereas the contralateral leg received sham treatment (CON). Muscle biopsies were obtained from the M. vastus lateralis from both the BFR and CON leg before and immediately after the 2 weeks of bed rest. Type I and II muscle fiber size, myonuclear content, capillarization, and SC content were assessed by immunohistochemistry.

No significant decline in either type I or type II muscle fiber size were observed following bedrest, with no differences between the CON and BFR leg (P>0.05). Type I muscle fiber capillary density increased in response to bed rest in both legs (P<0.05), while other muscle fiber capillarization measures remained unaltered. SC content decreased in both type I (from 7.4±3.2 to 5.9±2.7 per 100 fibers) and type II (from 7.2±3.4 to 6.5±3.2 per 100 fibers) muscle fibers (main effect of time P=0.018), with no significant differences between the BFR and CON leg (P>0.05).

In conclusion, two weeks of bed rest has no effect on muscle capillarization, decrease the SC content and daily BFR treatment does not affect skeletal muscle fiber size and SC content in healthy, young men.

Link | PDF (Journal of Applied Physiology)

 

I've only skim-read through once, but I think the body of the paper indicates that capillaries (numbers) do not decline with bed rest, even though the muscle fibres themselves reduce in size. So capillary density increases. They also say capillary contact points on individual fibres don't change. Findings in relation to the control leg.

Methods —

Discussion —

That passage is also a little confusing to interpret.

We should probably have a look at [9]

[9] Daily blood flow restriction does not preserve muscle mass and strength during 2 weeks of bed rest (2024, The Journal of Physiology) [Open access]
[18] Interrelationships between skeletal muscle adaptations and performance as studied by detraining and retraining (1979, Acta Physiologica Scandinavica) SciHub
[20] Adaptive changes in work capacity, skeletal muscle capillarization and enzyme levels during training and detraining (1981, Acta Physiologica Scandinavica) SciHub

 

I haven't looked closely at the satellite cell passages, but I thought it might be useful to have this paper noted (+/- its predecessors) so we might be able to compare with LC/ME biopsy findings. Hopefully, the upcoming Wüst/Appleman paper will report on more definitive direct comparisons between ME/LC vs normals-after-bedrest.