title: Skeletal muscle microvascular function in girls with Turner syndrome.
abstract: BACKGROUND
  Exercise intolerance is prevalent in individuals with Turner Syndrome (TS). We recently demonstrated that girls with TS have normal aerobic but altered skeletal muscle anaerobic metabolism compared to healthy controls (HC). The purpose of this study was to compare peripheral skeletal muscle microvascular function in girls with TS to HC after exercise. We hypothesized that girls with TS would have similar muscle blood-oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) signal responses during recovery from exercise compared to HC.
  
  
  METHODS
  Thirteen TS participants and 8 HC completed testing. BOLD MRI was used to measure skeletal muscle microvascular response during 60 second recovery, following 60 s of exercise at 65% of maximal workload. Exercise and recovery were repeated four times, and the BOLD signal time course was fit to a four-parameter sigmoid function.
  
  
  RESULTS
  Participants were 13.7 ± 3.1 years old and weighed 47.9 ± 14.6 kg. The mean change in BOLD signal intensity following exercise at the end of recovery, the mean response time of the function/the washout of deoxyhemoglobin, and the mean half-time of recovery were similar between the TS and HC groups.
  
  
  CONCLUSIONS
  Our results demonstrate that compared to HC, peripheral skeletal muscle microvascular function following exercise in girls with TS is not impaired.
  
  
  CONCLUSIONS
  This study supports the idea that the aerobic energy pathway is not impaired in children with TS in response to submaximal exercise. Other mechanisms are likely responsible for exercise intolerance in TS; this needs to be further investigated.
authors.affiliation: Faculty of Kinesiology and Physical Education, The University of Toronto, Canada ; Physiology and Experimental Medicine, The Hospital for Sick Children, Canada.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: West
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children, Canada ; Division of Endocrinology, The Hospital for Sick Children, The University of Toronto, Canada.
authors.forename: Clodagh S
authors.initials: CS
authors.lastname: O'Gorman
authors.affiliation: Physiology and Experimental Medicine, The Hospital for Sick Children, Canada.
authors.forename: Alyaa H
authors.initials: AH
authors.lastname: Elzibak
authors.affiliation: Faculty of Kinesiology and Physical Education, The University of Toronto, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Caterini
authors.affiliation: School of Biomedical Engineering, McMaster University, Canada ; Department of Electrical and Computer Engineering, McMaster University, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Noseworthy
authors.affiliation: Department of Diagnostic Imaging, The Hospital for Sick Children, Canada.
authors.forename: Tammy
authors.initials: T
authors.lastname: Rayner
authors.affiliation: Division of Endocrinology, The Hospital for Sick Children, The University of Toronto, Canada.
authors.forename: Jill
authors.initials: J
authors.lastname: Hamilton
authors.affiliation: Faculty of Kinesiology and Physical Education, The University of Toronto, Canada ; Physiology and Experimental Medicine, The Hospital for Sick Children, Canada.
authors.forename: Greg D
authors.initials: GD
authors.lastname: Wells
keywords: BOLD MRI; Exercise; Microvascular function; Pediatric; Skeletal muscle; Turner syndrome