What does leisure time physical activity mean to workers doing manual labour?

A Danish study found an association between high-intensity leisure time physical activity and greater work ability among 50 – 70-year-olds doing manual labour. The researchers also found that leisure time physical activity was associated with a lower risk of chronic knee pain.

The increased retirement age in Denmark is caused in part by the increased life expectancy and a forecasted doubling of the number of people over 60 years of age by the year 2050. Since the manual labour ability decreases and the prevalence of MSK disorders increases with age, the increased retirement age may pose a challenge for persons doing manual labour in particular.

Leisure time physical activity may be one solution, but it is not clear how it affects workability in individuals doing manual labour, and if increased leisure time physical activity is beneficial or increases the risk of MSK disorders. Therefore, researchers studied the association between both low and high intensity leisure time physical activity and their ability to do manual labour and chronic MSK disease.

A questionnaire was completed by 1763 workers aged 50 to 70 years. The participants were asked how much time they used per week on high and low intensity leisure time activities, their ability to do manual labour and chronic (>90 days) MSK pain during the previous 12 months. The analyses took into account age, sex and health and work-related factors.

The participants averaged 57 years of age with 98 % being male; most worked as carpenters, electricians or bricklayers. In their leisure time, 60% reported 3 or more hours of low intensity physical activity, and 44% reported 3 or more hours of high intensity physical activity. Approximately 30 % reported their ability to do manual labour as very good or excellent. Every fourth participant reported chronic knee-, neck-, shoulder- or low back pain.

The researchers found that participants who reported high intensity activity of at least 3 hours duration per week had higher ability to do manual labour, while shorter high intensity activity and low intensity physical activity of any duration were not related to the ability to do manual labour. Both high and low intensity physical activity were related to less knee pain, while it was unclear if it was related to less pain in other body parts.

The study had a few limitations. It was a cross-sectional study, which means it was not possible to conclude anything about causality (i.e., if physical activity influences work ability or vice versa). Measuring self-reported physical activity is prone to measurement errors and bias; often duration and intensity are overestimated. Furthermore, the participants’ physical activity at work, sedentary behaviour and sleep were not taken into account despite the make-up of the whole 24 hours being important to our health.

The duration of both low and high intensity leisure time physical activity may be important to both the ability to do manual labour and chronic MSK disease among 57 to 70-year-old persons doing manual labour. If chiropractors recommend increased physical activity to patients with chronic pain, they should take into consideration the patient’s other physical activity level and possible recovery.

Norheim KL, Samani A, Hjort Bonlokke J, Omland O, Madeleine P. Physical-work ability and chronic musculoskeletal complaints are related to leisure-time physical activity: Cross-sectional study among manual workers aged 50-70 years. Scandinavian journal of public health. 2019https://pubmed.ncbi.nlm.nih.gov/30973060/