title: Quantitating the capillary supply and the response to resistance training in older men.
abstract: Resistance training (RT) has been shown to increase aerobic power in older humans. To determine the effects of RT on the capillary supply in this population, nine older men (65-74 y) engaged in 9 weeks RT of the lower body. Following RT, peak O2 uptake (V.O2,peak) increased by 7% (P<.01). Needle biopsies (vastus lateralis muscle) revealed significant increases (mean +/- SE) in fibre area (3,874 +/- 314 microm2 to 4,778 +/- 309 microm2), fibre perimeter (P, 262 +/- 11 microm to 296 +/- 11 microm), capillary contacts (3.7 +/- .2 to 4.3 +/- .3) and the individual capillary-to-fibre ratio (C:Fi, 1. 33 +/- .32 to 1.61 +/- .37, P<.005). To evaluate the potential for blood-tissue exchange, both fibre area-based and perimeter-based measures of the capillary supply were compared. While the area-based measures were maintained, C:Fi/P was increased, consistent with an increase in the size of the fibre-capillary interface and thus, an increased potential for oxygen flux following RT. Of the measurements of capillary supply, V.O2,peak correlated best with C:Fi/P (r = 0.69, P<.005). These results indicate a significant increase in the capillary supply relative to the perimeter, but not the cross-sectional area, of the muscle fibres following RT in older men, and that C:Fi/P is strongly correlated to the V.O2,peak in this population.
authors.affiliation: Dept. of Physiology, University of Toronto, Toronto, Canada M5S 3J7.
authors.forename: R T
authors.initials: RT
authors.lastname: Hepple
authors.forename: S L
authors.initials: SL
authors.lastname: Mackinnon
authors.forename: S G
authors.initials: SG
authors.lastname: Thomas
authors.forename: J M
authors.initials: JM
authors.lastname: Goodman
authors.forename: M J
authors.initials: MJ
authors.lastname: Plyley
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D002196:Capillaries / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*