Heart Rate Variability in Duchenne Muscular Dystrophy During Computer Task
Condition: Duchenne Muscular Dystrophy
MeSH terms: Muscular Dystrophies; Muscular Dystrophy, Duchenne
Study type: Observational

Summary: 
      HRV is attained using a Polar RS800CX. Then, evaluated through linear, non-linear and chaotic
      global techniques (CGT). Forty-five male subjects were included in the DMD group and
      age-matched with forty-five in the healthy Typical Development (TD) control group. They were
      assessed for twenty minutes at rest sitting, and then five minutes whilst performing the maze
      task on a computer.
    

Detailed description: 
      This is a cross-sectional study, where HR was recorded beat-to-beat (RR intervals) using the
      portable Polar RS800CX HR monitor (Polar Electro, Finland). HR was recorded before the onset
      and at the end of the five minutes of the computer maze paradigm task.

      The subjects were seated in a standard chair (walkers, TD group and DMD) or in their own
      wheelchair (non-walkers, DMD group), the Polar watch was positioned on the wrist. The
      analysis of HRV was possible through the recording of RR interval in two periods: the period
      of twenty minutes at seated rest, and then during the computer task for five minutes.

      The computer task used a maze paradigm with one correct pathway that could be negotiated and
      ultimately solved. All participants were positioned comfortably and an evaluator responsible
      for instruction and annotation of data.

      Each individual was instructed to walk the correct path with the digital character pawn
      (pointed on the screen by the evaluator) to the exit of the maze identified by an "x"
      (pointed on the screen by the evaluator). It was provided for the subjects, who used the
      arrow buttons on the keyboard, identified by up, down, right and left, using the dominant
      hand, with the arrows moving through a 20 x 20 cm maze. Participants were requested to
      complete the maze as fast as possible.

      HRV analysis followed the guidelines published by the Task Force of the European Society of
      Cardiology and North American Society of Pacing and Electrophysiology. The RR intervals were
      recorded, and then were downloaded to the Polar Precision Performance program (v.3.0). This
      software enabled the visualization of HR and the extraction of a cardiac period (RR intervals
      series; the variation of beat-to-beat interval in milliseconds) file in ".txt" format. For
      analysis of HRV data at rest, we analyzed 1000 consecutive RR intervals, and for HRV analysis
      for the computational task, the number of consecutive RR intervals obtained was exactly 256
      RR intervals. Digital filtering complemented by manual filtering was performed to eliminate
      artifacts and only series with greater than 95% of sinus beats were included in the study.
      HRV analysis was undertaken through linear, non-linear and chaotic global techniques (CGT).
    

Intervention name(s): Duchenne Muscular Dystrophy group; Typical Development group
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Assessment of heart rate variability at rest and during computational task in people with Duchenne muscular dystrophy; Assessment of heart rate variability at rest and during computational task in people with typical Development
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        45 individuals with DMD (convenience sample) and 45 age-matched healthy TD individuals
        participated in the trial.
      
Keywords: Heart rate variability; Duchenne muscular dystrophy; Typically developed; Autonomic nervous system; Chaotic global techniques