| The complex relationship between physical work capacity, patterns of work, and worker productivity has been explored in many ways. A growing body of literature suggests that pacing and patterns of work are important, but methodological refinements are needed. Using data from the China Productivity Project, a study of Chinese cycle haulers in urban Beijing, this study explores the relationship between physical working capacity (assessed as VO2max) and work variability as reflected in heart rate records of real-world work. In addition, the effects of work intensity (% of VO2max), work duration and quantity of work (energy expenditure) on work variability are examined. A novel method for automated extraction of activity data from heart rate records and computation of work variability within extracted periods of work activity is presented. Chinese haulers do not have especially high physical work capacity (3.08 +/- 0.40 l/min, 49.2 +/- 6.2 ml/kg/min). During periods of work, haulers performed at an average of 49.8% of VO2max with some periods exceeding 80%, though pacing and limited duration of work generally result in more moderate levels of overall performance. There is some evidence for a relationship between VO2max and work variability, but only on certain work variability measures. Stronger relationships exist between work variability and intensity, duration and quantity of work. Three distinct patterns of variability are apparent in periods of work activity, with notable differences between periods of lower and higher work intensity. These results agree with and complement other published studies of work pacing and patterns, and the new methods presented may have applications in future investigations. |
