title: Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males.
abstract: Sprint interval training (SIT) has been proposed as a time efficient alternative to endurance training (ET) for increasing skeletal muscle oxidative capacity and improving certain cardiovascular functions. In this study we sought to make the first comparisons of the structural and endothelial enzymatic changes in skeletal muscle microvessels in response to ET and SIT. Sixteen young sedentary males (age 21 ± SEM 0.7 years, BMI 23.8 ± SEM 0.7 kg m(-2)) were randomly assigned to 6 weeks of ET (40-60 min cycling at ∼65% , 5 times per week) or SIT (4-6 Wingate tests, 3 times per week). Muscle biopsies were taken from the m. vastus lateralis before and following 60 min cycling at 65% to measure muscle microvascular endothelial eNOS content, eNOS serine(1177) phosphorylation, NOX2 content and capillarisation using quantitative immunofluorescence microscopy. Whole body insulin sensitivity, arterial stiffness and blood pressure were also assessed. ET and SIT increased skeletal muscle microvascular eNOS content (ET 14%; P < 0.05, SIT 36%; P < 0.05), with a significantly greater increase observed following SIT (P < 0.05). Sixty minutes of moderate intensity exercise increased eNOS ser(1177) phosphorylation in all instances (P < 0.05), but basal and post-exercise eNOS ser(1177) phosphorylation was lower following both training modes. All microscopy measures of skeletal muscle capillarisation (P < 0.05) were increased with SIT or ET, while neither endothelial nor sarcolemmal NOX2 was changed. Both training modes reduced aortic stiffness and increased whole body insulin sensitivity (P < 0.05). In conclusion, in sedentary males SIT and ET are effective in improving muscle microvascular density and eNOS protein content.
authors.affiliation: Exercise Metabolism Research Group, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Cocks
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Shaw
authors.forename: Sam O
authors.initials: SO
authors.lastname: Shepherd
authors.forename: James P
authors.initials: JP
authors.lastname: Fisher
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Ranasinghe
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Barker
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Tipton
authors.forename: Anton J M
authors.initials: AJ
authors.lastname: Wagenmakers
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D001794:Blood Pressure; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D055806:Microvessels; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology*; D057185:Sedentary Behavior; D059289:Vascular Stiffness; D055815:Young Adult
chemical_list: D008562:Membrane Glycoproteins; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases