Exercise as it relates to Disease/Quantifying occupational physical activity manual labour vs office workers

This is a critique of the research article: Occupational Physical Activity in Brewrey and Office workers

What is the background to this research?
Physical inactivity has been classified as the 4th most common risk factor for global mortality. With known health risks associated physical inactivity it is still estimated that only around 5% of American adults meet physical activity guidelines. However, with increasing growth and use of technology to aid in professional life has manufactured an a prevalent physically inactive life style.

Self-reporting measures of physical activity have previously been the primary source of obtaining physical activity or occupational physical activity measures. Though many suggestions of validity and reliability, some literature has suggested a limitation in assessing absolute measures as well as intensity of physical activity using self-reporting questionaries for physical activity. Developing accelerometry technology has been proposed to be a valid and reliable as well as practical method of quantifying the amount and intensity of physical activity as well as sedentary behaviour.

The purpose of this study was to assess the occupational physical activity levels between a generally physically active and relatively sedentary work environments. Additionally, this study assessed the level of agreement between two types of accelerometer-based activity trackers.

Where is the research from?
Thompson, Severson and Rosecrance’s article was published in the Journal of Occupational and Environmental Hygiene (JOEH). JOEH is a joint publication of the American Industrial Hygiene Association and The American Conference of Governmental Industrial Hygienists, dedicated to enhancing knowledge and practice of occupational and environmental hygiene and safety.

This was Janalee’s first publication while at the Centre for Health, Work & Environment at the Colorado School of Public Health. She than followed with her second publication relating to Total Worker Health relating to a small business leader perspective. Janalee has since becoming a Safety and Industrial Hygiene Professional II at City and County of Denver, Denvor Public. This suggests a great eagerness and depth of experience within the field of occupational health. Severson and Rosecrance have both also published several journals within this field.

This research was conducted in the United States of America however, is still relevant within Australia.

What kind of research was this?
This research was conducted classified as an observational study due to the purpose in which to quantify the physical activity within two working populations. It could be suggested that it consists of possible quasi-experimental components as there was no control group within the design. The study may also be considered to be cross-sectional designed as there is a comparison element with physical activity between two different occupation groups as well as between accelerometry devices. As the purpose of this study was to observe the physical activity levels related to occupational groups as well as assess the variability between devices, this study design is appropriate.

What did the research involve?
This research originally consisted of 101 participants. Of which 50 volunteers from which were within the physically activity occupation group (brewery) and 51 volunteers from the office-based occupation group (call centre an engineering department). However, the final data analysis was conducted on 47 participants from the brewery and 47 office workers due to removal policies relating to device connection, consumption of medication relating affecting heart rate and abnormal physical activity due to knowledge of physical activity recording. The physical activity of each participant was recorded for one working shift. Physical activity for these participants were measured using both a Fitbit Charge HR and a Hexoskin to obtain two separate interpretations. Each participant was allocated both a Fitbit Charge HR and a Hexoskin and asked to wear them for an entire singular work day. from this the following was recorded:


 * Steps (Steps per hour)
 * Heart rate (bpm)
 * Percent maximal HR Range (%)
 * Calories (kcal)
 * METS (only determined from the Fitbit)

Percentage maximal HE range was determined using the following formula:

100 x (Average HR on job-Resting HR)/(Predicted HRmax-Resting HR)

Predicted HRmax was found using the age dependent formula for maximal HR (220-age in bpm). Whereas, the resting HR was defined as the lowest mean HR for a 60sec time period while sitting during the shift.

Limitations related to this study need to be considered whilst interpreting the relating results. Whilst the Fitbit Charge HR is popular device, it has the ability to falsely record additional data when misinterpreting additional arm-based movements as steps. This device also has the ability to present possible bias relating to abnormal extra physical activity due to its obvious presence on the wrist. Additionally, the percentage maximal HR range’s validity could be questioned as a true resting HR was unable to be found, instead using the lowest mean HR at work for 60 seconds. The participant recruitment method of occupation management asking employees for expressions of interest, resulting in a possible ‘healthy worker effect’, including those with an already increased physical activity or healthy lifestyle participating. Finally, the duration of data collection was only the duration of one shift with shifts ranging from 5-12 hours. This may not give a true representation of the occupation populations physical activity levels.

What were the basic results?
Statistical analysis investigating the difference between groups measures of steps, HR average percent maximal HR range and energy expenditure, using a two-sample t-test. A two-factor ANOVA was also used to assess the difference in mean hourly steps, mean HR, between devices and between occupational groups. Finally, a Bland-Altman plot was used to analyse and quantify agreement and bias between mean differences. All statistical significance was determined to the level of 0.05 for all tests.

Reliability was found to be of moderate for hourly steps and good for mean HR within both devices. Significant differences were found between devices for both measures of hourly steps and HR. Fitbit Charge HR consistently measures higher mean hourly steps whereas the Hexoskin consistently measured greater mean HR. Brewery workers took more steps, had greater mean HR and maximal percent HR range, and higher energy expenditure than office workers. The following table 1. Summarizers means for, SD, difference between means and p-values for all measured factors.

What conclusions can we take from this research?
Significant differences were found in the physiological cost related to office workers compared to brewery workers. Differences in mean hourly steps and heart rate between occupations suggests it is important to understand the physical activity demands related to each occupation. The Hexoskin was reported to have invasive properties and therefore would not be recommended to record occupational physical activity levels. The Fitbit charge HR appears to be a practical tool to observe occupational physical activity, however, it too does possess some limitations and therefore may need to undergo resting to assess reliability and validity.

Practical advice
This study aids in adding depth into understanding physical activity levels within an different occupational environments. This research along with the previous research indicating the possible negative effects related to sedentary and physical inactivity lifestyles, may help business owners or employers implement initiatives to help increase OPA levels. On the other hand, it may also aid in predicting or evaluating levels of fatigue within more physically active occupations. Wearable devices are continuing to be developed and advanced and their validation should be continuously be assessed against proven methods. If work place duties are designed with OPA in mind and physical activity guidelines, then a healthier workplace could be obtained.

Further information/resources
World Health Organisation

The Australian Department of Health: For Australian Physical Activity and Sedentary Behaviour Guidelines An office-place stepping device to promote workplace physical activity