Physical health, work demands and capacity among offshore wind technicians

As the offshore wind industry matures and expands, the need for skilled and healthy offshore workers increases. However, offshore wind service technicians (WTs) self-report high physical working demands whilst being exposed to numerous health, environmental and safety hazards, which may lead to a high prevalence of health implications and early exit from the labor market. Basic knowledge on the interplay between physical health, physical work demands, and physical capacity of WTs, as well as possible health and capacity enhancing strategies, are therefore warranted. Thus, the present PhD thesis aimed to answer the following questions:

I. What is the prevalence, severity, and impact of musculoskeletal disorders and the perceived duration of physical work demands between turbine sizes among offshore WTs? 

II. What are the objectively measured physical work demands of offshore WTs in different work settings (during onshore and offshore workdays) and do the physical work demands match the physical capacity of the workforce? 

III. What is the feasibility and preliminary efficacy of implementing an adapted version of Intelligent Physical Exercise Training (IPET) targeting workplace and WT needs as well as their physical work demands?

To address the aims, the three following studies were conducted:

I. A cross-sectional survey across the entire population of WTs within a single large offshore wind company. WTs from the United Kingdom and Denmark self-reported musculoskeletal disorders, durations of physical work demands, and turbine size (small, medium, large) defined by the reported work site. Descriptive statistics, analysis of 14 variance and logistic regression analyses were used to report health and performance outcomes between turbine sizes.

II. In continuation, an observational field study was conducted to assess the physical work demands in terms of cardiorespiratory load (heart rate reserve capacity), duration of activity types (lying, sitting, standing, moving, walking, climbing) and awkward postures (forward bent, arms elevated, and kneeling). Specifically, WTs were equipped with heart rate monitors and accelerometers (five placements) for a period between one and seven workdays. Indirect VO2max testing was further conducted. Differences in physical work demands between onshore (stand-down) and offshore (service and maintenance) workdays were evaluated using the Wilcoxon signed rank test. 

III. Finally, a non-randomised feasibility study (III) was conducted to assess the feasibility (compliance, adherence, adverse events, and participant acceptability) and preliminary efficacy (health indicators and physical capacity) of IPET (one hour/week structured and individualized exercise during working hours). The intervention period was 12 weeks, with the first eight weeks taking place on-site (supervised exercise during work hours) and the last four weeks being home-administered. Descriptive statistics were used to present feasibility outcomes and parametric pairwise comparisons were performed to assess for differences in secondary outcomes between time points.

In summary, the cross-sectional survey study (study I: n=176) revealed high prevalence (68%) and severity (median of 5 (0-10 on a numerical rating scale)) of musculoskeletal disorders and high perceived physical work demands. WTs servicing large turbines experienced fewer musculoskeletal disorders (odds ratio of 0.15 [95% confidence interval: 0.04 to 0.58]) and reported lower physical work demands compared with small turbines. The observational field study (study II: n=27) did not confirm the excessively high levels of perceived physical work demands; however, comparable levels with other types of blue-collar workers were found. The observed relative physical work demand (cardiovascular load) was 22% of the heart rate reserve capacity, which is considered well-within the proposed safe occupational limit of maximally ~30%. Significantly higher demands were observed on days working offshore compared with onshore workdays. Findings from study I and II helped inform the adapted version of IPET which was trialed for feasibility for 12 weeks (study III: n= 24). Compliance, adherence, and acceptability was high for the structured exercise training during working hours (>80%). Physical capacity and health parameters increased before and during the intervention period, indicating large seasonal fluctuations in addition to any improvements caused by the intervention.
This thesis provides new knowledge on self-reported and objectively measured physical work demands and health profiles of WTs in the offshore wind industry. Furthermore, indications of structured exercise during working hours being a feasible and effective strategy for improving measures of physical health, capacity, and demands across the population of WTs were obtained. The new knowledge may inform data-driven practices for health surveillance, promotion and requirements, whilst being incorporated into existing company and industry specific guidelines and standards for physical work demands, health and capacity.