Physical activity measurement using MTI (actigraph) among children with cerebral palsy

Arch Phys Med Rehabil. 2010 Aug;91(8):1283-90. doi: 10.1016/j.apmr.2010.04.026.


Objective: To investigate the validity of MTI accelerometer as a physical activity (PA) measurement instrument for children with cerebral palsy (CP).

Design: Participants were classified within Gross Motor Function Classification System I to III and took part in 2 activity sessions: (1) a structured activity protocol with increasing intensities and (2) a free play session. Concurrent measurements of activity counts, heart rate, and observed physical activity were performed.

Setting: Data were collected on normal school days in special schools within the participants' 30-minute break period.

Participants: Convenience sample of children with CP (N=31; 17 girls, 14 boys) age between 6 and 14 years (mean +/- SD, 9.71+/-2.52 y).

Interventions: Not applicable.

Main outcome measures: MTI measured activity counts, a monitoring device measured heart rate, and the System for Observing Fitness Instruction Time (SOFIT) was used for direct PA observation.

Results: There were strong relationships between MTI and SOFIT (r=.75; R(2)=.56; P<.001) and heart rate monitor (HRM) and SOFIT (r=.65; R(2)=.43; P<.001) data in structured activities, but the difference between these 2 correlation coefficients was not significant (P=.46). In free play activities, the association between MTI and SOFIT data (r=.67; R(2)=.45; P<.001) was significantly stronger (P=.01) than that between heart rate and SOFIT data (r=.14; R(2)=.02; P<.001) . Bland-Altman plots showed better agreement between observed SOFIT and MTI-predicted SOFIT data than observed SOFIT and HRM-predicted SOFIT data from the linear regression analysis.

Conclusions: The findings suggest that the MTI appears to be a valid instrument for measuring raw activity volume among children with CP and is suitable for use in studies attempting to characterize the PA of this population.

MeSH terms

  • Actigraphy / methods*
  • Adolescent
  • Cerebral Palsy / physiopathology*
  • Child
  • Disability Evaluation
  • Exercise / physiology*
  • Female
  • Heart Rate
  • Humans
  • Male
  • Mobility Limitation
  • Physical Therapy Modalities
  • Reproducibility of Results