Influence of gait analysis on decision-marketing for lower extremity surgery

Prediction of mechanical efficiency from heart rate during stair-climbing in children with cerebral palsy


  1. 1. Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva;
  2. 2. Human Motion Analysis Laboratory, Assaf-Harofeb Medical Center, Zerifin, Israel;
  3. 3. Cardiology Section, VA Medical Center, Albuquerque, NM, USA

Background: Mechanical efficiency (ME) quantifies the energy expended to perform a measured amount of external work. Skilled motor performance is characterized by increased ME, as the task is performed with reduced energy expenditure. The stair-climbing test indicates significantly lower ME in children with cerebral palsy (CP; 2-5%) compared with  typically developing (TD) children (near 20%). 1

Objectives: The aim of this study was to determine the accuracy of predicting ME from heart rate (HR) during a self-paced stair-climbing test in children with a range of motor abilities.

Design: Instrument development and validation study.

Participants: A convenience sample of 12 TD children and 24 with CP, ranging in age from 5 to 15 years (mean 8y). Five children with CP were at Level II, 11 at Level III, and 8 at Level IV of the Gross Motor Function Classification System.

Method: During the 5-minute resting that preceded 4 minutes of stair climbing, the HR and VO2 were measured breath-by-breath and the values for the 3rd and 4th minutes were subsequently averaged. ME was calculated as the ratio of external work to 02 uptake (VO2) measured or predicted from HR.

Results: Results demonstrated that the absolute values of VO2 and HR during stair-climbing were not correlated. However, the corr4elation between values above resting (dVO 2 and dHR) was high (r=0.61) and significant  (p<0.001). Furthermore, when body weight was included as a second variable, the prediction of dVO2 was improved (r=0.85). This resulted in a high correlation (r=0.96) between measured and predicted net ME (MEnet). Values of MEnet for 25 stair-climbing tests repeated after an average of 6 months resulted in an r-value of 0.92 with MEnet of the first test.

Conclusion: This study demonstrates that MEnet can be predicted in children with a raqnge of motor abilities from dHR and body weight during a stair-climbing test and these values demonstrate adequate repeatability to make them useful as a whole-body measure for evaluating improvement of skills or the efficacy of interventions.

Reference:Bar-Haim S, Belokopytov M, Harries N, Frank A. (2004) A stair-climbing test for ambulatory assessment of children with cerebral palsy. Gait Posture 20: 183-188.

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