title: Effect of time ratio of heat to cold on brachial artery blood velocity during contrast baths.
abstract: BACKGROUND
  Contrast baths have been adopted widely in clinics. However, the time ratio of heat to cold modalities has not been well established.
  
  
  OBJECTIVE
  The purpose of this study was to explore the effect of time ratio on brachial artery mean blood velocity (aMBV) and determine the optimal duration in the second heating phase.
  
  
  METHODS
  This was a within-participant, repeated-measures, experimental study.
  
  
  METHODS
  Thirty-four young volunteers who were healthy were recruited. Each participant performed 2 kinds of contrast baths within 2 separate sessions. In the first trial with a fixed time ratio, participants immersed their left hands in a 40°C hot bath for 3 minutes and then in an 18°C cold bath for 1 minute. This procedure was repeated 3 times. In the second trial, after the initial 3-minute hot bath and 1-minute cold bath, a 10-minute 40°C hot bath immersion was adopted as the second cycle. A color Doppler ultrasound scanner was used to measure aMBV, which was used to calculate the percentage of change related to the baseline (aMBV%) and the fluctuation in the heating phases (ΔaMBV%).
  
  
  RESULTS
  In the first trial, compared with the first heating phase, the ΔaMBV% was significantly lower by 57% and by 46% in the second and third heating phases, respectively. In the second trial, the ΔaMBV% beyond the 7th minute did not reach a significantly lower level.
  
  
  CONCLUSIONS
  The results cannot be generalized to elderly individuals or patients with medical conditions.
  
  
  CONCLUSIONS
  A longer duration in the second heating phase during contrast baths was required to produce a sufficient fluctuation in blood flow.
authors.affiliation: Department of Physical Therapy, Tzu-Chi College of Technology, Department of Physical Therapy, Tzu-Chi University, Hualien, Taiwan.
authors.forename: Chiao-Yu
authors.initials: CY
authors.lastname: Shih
authors.forename: Wen-Li
authors.initials: WL
authors.lastname: Lee
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Lee
authors.forename: Chien-Hui
authors.initials: CH
authors.lastname: Huang
authors.forename: Yu-Zu
authors.initials: YZ
authors.lastname: Wu
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001494:Baths; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging* / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D006225:Hand / Q000098:blood supply* / Q000000981:diagnostic imaging*; D006358:Hot Temperature; D006801:Humans; D007101:Immersion; D008297:Male; D013997:Time Factors; D018615:Ultrasonography, Doppler, Color