title: Post-warm-up muscle temperature maintenance: blood flow contribution and external heating optimisation.
abstract: OBJECTIVE
  Passive muscle heating has been shown to reduce the drop in post-warm-up muscle temperature (Tm) by about 25% over 30 min, with concomitant sprint/power performance improvements. We sought to determine the role of leg blood flow in this cooling and whether optimising the heating procedure would further benefit post-warm-up T m maintenance.
  
  
  METHODS
  Ten male cyclists completed 15-min sprint-based warm-up followed by 30 min recovery. Vastus lateralis Tm (Tmvl) was measured at deep-, mid- and superficial-depths before and after the warm-up, and after the recovery period (POST-REC). During the recovery period, participants wore water-perfused trousers heated to 43 °C (WPT43) with either whole leg heating (WHOLE) or upper leg heating (UPPER), which was compared to heating with electrically heated trousers at 40 °C (ELEC40) and a non-heated control (CON). The blood flow cooling effect on Tmvl was studied comparing one leg with (BF) and without (NBF) blood flow.
  
  
  RESULTS
  Warm-up exercise significantly increased Tmvl by ~3 °C at all depths. After the recovery period, BF Tmvl was lower (~0.3 °C) than NBF Tmvl at all measured depths, with no difference between WHOLE versus UPPER. WPT43 reduced the post-warm-up drop in deep-Tmvl (-0.12 °C ± 0.3 °C) compared to ELEC40 (-1.08 ± 0.4 °C) and CON (-1.3 ± 0.3 °C), whereas mid- and superficial-Tmvl even increased by 0.15 ± 0.3 and 1.1 ± 1.1 °C, respectively.
  
  
  CONCLUSIONS
  Thigh blood flow contributes to the post-warm-up Tmvl decline. Optimising the external heating procedure and increasing heating temperature of only 3 °C successfully maintained and even increased T mvl, demonstrating that heating temperature is the major determinant of post-warm-up Tmvl cooling in this application.
authors.affiliation: Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.|Sport and Exercise Sciences Research Unit, University of Palermo, Palermo, Italy.
authors.forename: Margherita
authors.initials: M
authors.lastname: Raccuglia
authors.affiliation: Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
authors.forename: Alex
authors.initials: A
authors.lastname: Lloyd
authors.affiliation: Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
authors.forename: Davide
authors.initials: D
authors.lastname: Filingeri
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
authors.forename: Steve H
authors.initials: SH
authors.lastname: Faulkner
authors.affiliation: Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Hodder
authors.affiliation: Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK. G.Havenith@lboro.ac.uk.
authors.forename: George
authors.initials: G
authors.lastname: Havenith
mesh_terms: D001831:Body Temperature; D001833:Body Temperature Regulation; D006358:Hot Temperature; D006801:Humans; D007866:Leg / Q000098:blood supply / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D012039:Regional Blood Flow; D063996:Warm-Up Exercise; D055815:Young Adult
keywords: Blood flow; Muscle temperature; Occlusion; Passive heating; Water perfused trousers