Ergonomics Work demands and need for recovery ...

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Ergonomics

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Work demands and need for recovery from work in ageing seafarers R. S. Bridgera; K. Brashera; A. Dewa a Human Factors Department, Institute of Naval Medicine, Alverstoke, Hants, UK Online publication date: 22 July 2010

To cite this Article Bridger, R. S. , Brasher, K. and Dew, A.(2010) 'Work demands and need for recovery from work in

ageing seafarers', Ergonomics, 53: 8, 1006 — 1015 To link to this Article: DOI: 10.1080/00140139.2010.493958 URL: http://dx.doi.org/10.1080/00140139.2010.493958

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Ergonomics Vol. 53, No. 8, August 2010, 1006–1015

Work demands and need for recovery from work in ageing seafarers R.S. Bridger*, K. Brasher and A. Dew Human Factors Department, Institute of Naval Medicine, Crescent Rd, Alverstoke, Hants PO12 2DL, UK

Downloaded By: [Bridger, RS] At: 09:23 23 July 2010

(Received 26 January 2010; final version received 10 May 2010) This study was conducted on a population of seafarers serving in the Royal Fleet Auxiliary (RFA), the organisation providing support at sea to the Royal Navy. An investigation into work-related fatigue in RFA personnel onboard ships was carried out following changes to the regulations concerning maximum retirement age, to determine whether age was associated with recovery from work demands. A total of 322 personnel aged from 19 to 61 years were interviewed onboard seven RFA ships. The Need for Recovery scale was used to measure fatigue and work demands exposure was measured using the Baecke questionnaire and the NASA Task Load Index. It was found that older personnel did not have higher work-related fatigue than younger personnel. A measure of frustration at work was found to be most strongly related to work-related fatigue, even in seafarers who carried out physically demanding jobs. Work-related fatigue was found to accumulate over time in personnel who continued to be exposed to work demands onboard a ship. Finally, a relatively high level of work-related fatigue was found in the RFA sample as a whole, which may hold implications for management interventions. It was concluded that older personnel in the RFA can cope with the day-to-day demands of working life as well as younger personnel, possibly due to a ‘survivor effect’, whereby those personnel who do not cope as well with work demands leave and find a different job, leaving only those who successfully deal with the demands of working life at sea. Statement of Relevance: In order to manage work demands in seafarers, it is important to identify the most fatiguing demands. Age is of interest because of the demographic ageing of the workforce. Age was not associated with a higher need for recovery. Psychological work demands had a greater effect on need for recovery than physical work demands. Keywords: ageing; need for recovery; work demands; shipping

1.

Introduction

Fatigue has been defined as ‘a subjective, unpleasant symptom which incorporates total body feelings ranging from tiredness to exhaustion, creating an unrelenting overall condition which interferes with an individual’s ability to function in their normal capacity’ (Ream and Richardson 1996). Fatigue can be difficult to measure in practice, but in recent occupational research, it has been measured indirectly in terms of need for recovery from work (Sluiter et al. 2003, Devereux and Rydstedt 2009). This concept refers to the perceived need to recover from the psychological and physical demands of a working day. In cases where individuals do not feel they have sufficient opportunity to unwind and recuperate from work, this deficit may be carried over to the next working day and accumulate over time (van der Beek et al. 1995). High need for recovery can be an indicator of increased susceptibility to health problems in a working population – it has been associated with the development of psychosomatic health complaints and

*Corresponding author. Email: [email protected] ISSN 0014-0139 print/ISSN 1366-5847 online Ó 2010 Taylor & Francis DOI: 10.1080/00140139.2010.493958 http://www.informaworld.com

risk of cardiovascular disease in working populations (Sluiter et al. 2003). There is some evidence that older workers have a higher need for recovery than younger workers when performing the same workplace tasks (Kiss et al. 2008, Devereux and Rydstedt 2009). Given the increasingly common trend to work into older age (Office for National Statistics, 2010), the capability of the older workforce to cope with the demands of working life is a concern of increasing relevance. Indeed, as Devereux and Rydstedt (2009) point out, by 2020 approximately one third of the workforce in the UK will be 50 years or older. It has long been known that certain faculties exhibit a general decline with age and the age of 50 years does appear to be a threshold at which marked declines do occur (Welford 1958). However, it is also possible that, as reported by Akerstedt et al. (2002), older workers may recover from work demands equally well, if not better, than younger personnel. For example, personnel who have been in employment longer may have developed more efficient coping strategies, or there may be a survivor effect in

Ergonomics


operation, whereby older personnel who were fatigued by their job demands move on and find a job to which they are more suited. There is renewed interest in the ageing workforce, due to changes in employment policy and practice and changing demographics in many countries. Much of the interest centres on the health and safety issues associated with the employment of older workers. These issues are of particular relevance for seafarers for the reasons described below. 1.1. Work demands of seafarers Working at sea poses additional demands on employees, over and above those commonly encountered in shorebased jobs. On large vessels, the additional musculoskeletal demands of counteracting the effects of motion are generally not large, but do contribute to the physiological cost of working at sea and may increase the time needed to complete tasks (Wertheim 1998, Crossland et al. 2007). Motion may also disturb sleep and cause sea-sickness, resulting in the accumulation of a sleep debt and acute malnutrition, respectively. The ‘Sopite syndrome’ (Ross 2009) is a form of motioninduced drowsiness that is associated with motion sickness. When working onboard ship, personnel are exposed to additional hazards, for example: using ladders and hatches to access their workspaces, which could result in an increased risk of slipping or falling at work; exposure to ship motion and increased risk of slipping, tripping and falling; poor weather conditions and heat, which can have a negative impact on performance; generally spending long periods aboard ship, isolated from family and with limited opportunity to disengage from the work environment, either mentally or physically. This lack of control over work and life may be stressful, according to the theory of Karasek and Theorell (1990). Disengagement from work is positively related to well-being (Sonnetag and Bayer 2005). On ships at sea, Royal Fleet Auxiliary (RFA) personnel are confined to the work environment for periods of 4 months and have few opportunities to engage with other environments. It can be argued that disengagement from work should lead to a change in the way mental resources are utilised and there is evidence that certain kinds of change have a more beneficial effect than others. Disengagement appears to be important for the restoration of attentional resources (Berman et al. 2008), but only when the environment newly engaged in makes low demands on directed attention. Clearly, seafarers are exposed to a multiplicity of factors that might cause them to become mentally and physically fatigued. Wadsworth et al. (2008) found that the number of negative occupational factors that

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personnel are exposed to (such as long work hours and poor sleep quality) was related to fatigue and that fatigue correlated positively with negative cognitive function. 1.2. Fatigue, fitness and the ageing workforce Personnel in the RFA are classed as merchant seamen and operate supply ships. As with most merchant seamen, the majority work exclusively aboard ship, where they occupy well-defined work roles (e.g. bosun, engineer, communications, steward). Working life on ship may become more difficult to cope with as personnel get older. Indeed, there are good a priori reasons for thinking that older personnel might be more prone to fatigue when working onboard a ship than younger personnel. For example, age-related decrements have been found in aerobic capacity, strength, eyesight, hearing, joint mobility, tissue elasticity, balance and proprioception, tolerance for heat and cold, recovery time after strenuous exertions, recovery of balance after slipping or tripping, reaction time, knee disorders and limb motility, all of which could be important in coping with working life onboard ship. Additionally, RFA personnel typically serve 4-month appointments onboard ship, which could render older personnel more susceptible to an accumulation fatigue. It is also possible that the relatively rigid work routine in the RFA may increase vulnerability to work-related fatigue, as it has been found that limited control over work breaks and chances to take leave can increase need for recovery (van Veldhoven and Sluiter 2009). The average age of personnel in the RFA is 42 years and is expected to increase in line with demographic trends. It is well established that health and fitness deteriorate with age (Welford 1958) but there is no regular fitness test as a requirement to serve in the RFA. This may mean that emerging health problems in this population are not managed, so there is an inflated risk of personnel working onboard ships who are not fully fit for work. According to the medical retirement data, RFA personnel are four times more likely to be medically retired due to musculoskeletal problems than Royal Navy personnel (Leonard 2006), where the mean age is 10 years lower. The present study was designed to assess physical and mental work demands of the seafarers, the degree of need for recovery in the workforce and any factors associated with a high need for recovery. It was carried out at the request of the management of the organisation due to concern about changes to retirement age and the ability of older workers to cope with working life aboard ship. However, as can be seen from the information above, age is only one of many factors that might cause fatigue in seafarers.

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1.3. Aims (1) To determine whether age was associated with need for recovery in seafarers. (2) To identify work demands associated with need for recovery. (3) To determine whether there is an accumulation of need for recovery over time whilst serving onboard ship and whether this is related to age.


2.

Method

2.1. Design Structured interviews were conducted with RFA personnel serving 4-month appointments onboard different ships. Need for recovery was measured at two time points to assess whether fatigue accumulates over time during an appointment onboard ship. Ethical approval was obtained from the Ministry of Defence Research Ethics Committee. 2.1.1. Pilot study The questionnaire measures were piloted with a sample of 20 personnel onboard a RFA vessel in port before the study commenced to ensure that the questions were appropriate for the target participants. 2.2. Participants A total of 322 RFA personnel from seven different ships were interviewed for this study. The overall participation rate was 58%. Participants were selfselected; personnel were provided with the opportunity to sign up for interview slots in advance or to turn up on the day whichever suited their working schedule. The mean age of the total sample was 42 years, which is equivalent to the average age of RFA personnel across the organisation. The ranking system categorises personnel as ratings (lower ranks) or officers (higher ranks). Ratings and officers have very different workloads, working hours and general lifestyles onboard so these two groups were examined separately. Table 1 shows the participation rates calculated by different demographic groups. The mean age of ratings was 42 years (ranging from 19 to 61 years) and the mean age of officers was 41 years (ranging from 23 to 61 years). Mann–Whitney U tests were used to assess response bias as age was not normally distributed (Kolmogorov–Smirnov revealed a significant deviation from normal distribution, p 5 0.001). Rank was found to differ significantly between responders and non-responders, as 72% of officers chose to take part, compared to only 53% of ratings (U ¼ 30314,

Table 1.

Participation rates within rank and age groups. Original sample size (n)

Group All Rank Rating Officer Age (years) 19–29 30–39 40–49 50–61

No. of participants (% of total sample)

Response rate (%)

552

322 (

58

392 160

207 (64) 115 (36)

53 72

98 118 191 145

64 67 107 84

65 57 56 58

(20) (21) (33) (26)

n1 ¼ 322, n2 ¼ 226, p 5 0.001). However there was no statistically significant difference between the ages of respondents (41.75 years) and non-respondents (43.10 years). In total, 42% of the study participants subsequently completed the 2 month follow-up questionnaire (n ¼ 134). Although this response rate was not high, the group of participants who responded at time point 2 were compared to the group of participants who did not respond. No significant differences were found between the groups in terms of age or in Need For Recovery (NFR) scale score at time point 1. 2.3. Measures The interview was structured using a questionnaire, which comprised three measures. 2.3.1.

Need For Recovery scale

The NFR scale is an 11-item scale developed in the Netherlands in 1994 (van Veldhoven and Meijman 1994) measuring the individual’s need for recovery after work. The rationale underpinning the scale is that the effect of work demands on personnel can be assessed by measuring the need to recover from work at the end of the working day. Indicators of fatigue assessed on the NFR scale include a lack of concentration and reduced motivation for activities at the end of the day. Participants are given dichotomous response options of ‘yes’ or ‘no’ to answer whether or not they experience each indicator. The total number of indicators present for each individual is converted into a scale score which ranges from 0 to 100, where higher scores show a greater need for recovery and thereby greater short-term work-related fatigue (Sluiter et al. 2003). The authors of the NFR scale have generated Dutch norms (J.K. Sluiter, personal communication, 2 September 2009), which were used to provide a comparison point for the current sample. From these norms, it is recommended that no more

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Ergonomics than 50% of the sample should score 36 or more on the NFR scale (equivalent to reporting about four or more indicators of fatigue on the 11-item NFR scale). The NFR scale is a widely used, reliable and valid measure, which detects the early indicators of work-related fatigue, and can be invaluable in early identification of fatigue symptoms. The scale has previously been found to predict occupational-related health complaints in coach drivers, including sleeping problems and emotional exhaustion (Sluiter et al. 1999), and to predict sickness absence from work due to psychological complaints (Sluiter et al. 2003). It is sensitive enough to detect an increase in work-related fatigue when working hours are increased (de Croon et al. 2006) and correlates highly with other measures of fatigue (de Croon et al. 2006). The scale also has good test–retest reliability over 2 years if the work environment remains relatively stable (0.68–0.80; de Croon et al. 2006). In addition to need for recovery, two established measures of task demands were included to ensure that there were no actual differences in the task demands of older and younger personnel and to assess whether these were related to need for recovery.

administer, is widely used and measures six dimensions of work demands. It is important to note that this study used the NASA TLX to assess general work demands rather than specific task demands and therefore it is not possible to compare the findings on this scale with other research studies. Instead, the primary use of this scale was to conduct comparisons between subjects within this study. 2.3.4.

Other variables

The structured interview also asked participants what date they joined their current ship for their present appointment and whether or not they were on shore leave prior to this. The RFA Human Resources personnel database was used to obtain the date of each participant’s last promotion and how many years they had served in the RFA. 2.3.5. Follow-up questionnaire The follow-up questionnaire comprised the NASA TLX and the NFR scale and participants were also asked to fill in the date on which they completed the follow-up. This was administered approximately 1–2 months after the initial interview.

2.3.2. Baecke Questionnaire This questionnaire was designed in 1982 by Baecke and colleagues to measure habitual physical activity in epidemiological studies. The questionnaire assesses regular physical activity (intensity, frequency and duration) for occupational and non-occupational tasks and sporting pursuits, producing three indices: a work index; a sport index; a leisure index. The Baecke questionnaire has high test–retest reliability over a 3month period (0.88, 0.81 and 0.74, respectively, Baecke et al. 1982), and has been validated against a physical activity diary (Pols et al. 1995). The range is from 1 to 5 for the work and leisure indexes and 1 to 20 for the sports index, with higher scores indicating greater activity. 2.3.3. NASA Task Load Index Because life aboard ship exposes personnel to a variety of work demands, the NASA Task Load Index (TLX) was chosen as a convenient tool to assess these using six subscales: mental demands; physical demands; temporal demands; effort; own performance; frustration (Hart and Staveland 1988). Participants were asked to rate their workload using these dimensions along numerical scales. Each of the six scales was analysed independently, with scores ranging from 1 to 20, where higher scores indicate greater task demands. The NASA TLX was chosen because it is quick to

2.4. Procedure Seven RFA ships were visited by two researchers between November 2008 and July 2009. Personnel serving on these ships received advance notice of the visit and the study purpose in the ship’s daily orders. The ships were also sent an interview time table 2 weeks prior to the visit and all personnel onboard were invited to sign up to an interview slot that was convenient for them. Once onboard, the researchers were allocated a cabin or conference room in which to conduct the interviews and each participant was interviewed by one researcher on an individual basis, during working hours. On arriving at the interview room, personnel were given a study information sheet, which explained the purpose of the research and what their participation would entail. After giving their informed consent, participants underwent a structured interview. Interviews took between 15 and 30 min to complete. The purpose of the study was explained to participants. Approximately 1–2 months after the initial interview was conducted, personnel were invited to complete the NASA TLX and NFR questionnaires a second time. These data were collected remotely by self-report questionnaire as it was not logistically possible for the interviewers to revisit each ship. The questionnaires were marked with an anonymous

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identity code, which enabled responses from the same individual to be linked, and allowed demographic information from the personnel database to be linked to questionnaire data.


3.

Results

The mean number of days that personnel had been working onboard their ship at the time of interview was 69 d (n ¼ 308, ranging from 1 to 199). Of the sample, 92% had been on shore leave prior to their current appointment onboard the ship on which they were interviewed. The NFR scale data were not normally distributed. The median score on the NFR scale for the total sample was 36.4 (range 0–100, where higher scores denote a greater need for recovery). Officers had significantly higher NFR scale scores than ratings (medians ¼ 45.5 and 36.4 respectively, U ¼ 10082, n1 ¼ 206, n2 ¼ 114, p ¼ 0.035). Therefore, the NFR data were analysed separately for ratings and officers. A median split was conducted on age for each group to allow comparison of NFR scale scores between younger and older personnel. The median ages were 44.9 years in the ratings group and 42.1 years in the officers group. Table 2 shows the median NFR scale scores and the percentage of personnel classified as having high NFR scale scores above the recommended cut-off (36.4 or above) according to the Dutch norms for the scale. This is divided into older and younger age groups for ratings and officers respectively using median splits. There were no significant differences between the NFR scale scores of ratings above and below the median split for age, or between the NFR scale scores of officers above and below the median split for age (U ¼ 4653.5, n1 ¼ 102, n2 ¼ 104, p ¼ 0.13, U ¼ 1290.5, n1 ¼ 57, n2 ¼ 57, p ¼ 0.06). A Spearman’s correlation was conducted to assess which of the variables measured were most strongly related to age in ratings and in officers. Years since last promotion, years of service in the RFA and mental demands of the working day as reported on the NASA

TLX correlated positively with age in ratings. The Baecke sport index score, frustration at work as reported on the NASA TLX and NFR scale scores correlated negatively with age in ratings. For officers, only years served and time since last promotion correlated significantly with age, see Tables 3 and 4. Stepwise multiple linear regression analyses were conducted to assess which variables were associated with NFR scale score for ratings and officers. Females were excluded from this analysis due to the small sample size. In both ratings and officers, the NASA TLX frustration score was most strongly associated with a high need for recovery after work. For ratings, high physical work demands were also associated with a high need for recovery. For officers, dissatisfaction with one’s own performance at work and high effort to complete daily work tasks were also associated with a high need for recovery. These results are shown in Tables 5 and 6. A total of 42% (n ¼ 134) of the study participants subsequently completed the follow-up questionnaire at time point 2, a mean of 41 d after being interviewed. The median NFR scale score at time point 2 was 45.5, Table 3. Correlation between age and work-related measures for ratings. Variable Time since last promotion (years) Time worked for RFA (years) Baecke sport index NASA TLX mental demands NFR scale score NASA TLX frustration Days spent onboard ship Baecke leisure index NASA TLX physical demands NASA TLX performance NASA TLX effort Baecke work index NASA TLX temporal demands Shore leave before this appointment

n

r

p

151 193 193 193 192 193 186 193 193 192 192 193 192 191

0.48 0.39 70.26 0.19 70.14 70.14 70.12 0.11 70.08 0.06 70.04 0.04 70.01 0.00

50.001 50.001 50.001 0.01 0.05 0.05 0.11 0.12 0.28 0.42 0.60 0.56 0.87 0.95

RFA ¼ Royal Fleet Auxiliary; TLX ¼ Task Load Index; NFR ¼ Need For Recovery. *Variables above the line are significantly related to age.

Table 2. Median Need For Recovery (NFR) scale scores and percentage of personnel with NFR scale scores above the recommended cut-off for older and younger personnel by rank. Age group Ratings below 44.9 years Ratings above 44.9 years Officers below 42.1 years Officers above 42.1 years

n

Median NFR scale score

% above cut-off*

102 104 57 57

36.36 31.82 45.45 36.36

55 50 72 51

*Sluiter (personal communication, 2009) recommended a cut-off score of 4 or more (scale score of 36.4) to indicate a high NFR at the organisational level.

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Ergonomics Table 4. Correlation between age and work-related measures for officers. Variable Time worked for RFA (years) Time since last promotion (years) Days spent onboard ship Baecke work index Baecke sport index NASA TLX frustration NFR scale score Baecke leisure index NASA TLX effort NASA TLX physical demands NASA TLX temporal demands Shore leave before this appointment NASA TLX mental demands NASA TLX performance

n

r

p

109 102 104 110 110 110 109 110 110 110 109 110 110 110

0.76 0.68 0.17 70.15 0.10 70.09 70.08 0.07 70.07 70.05 0.05 0.03 0.02 0.00

50.001 50.001 0.09 0.12 0.31 0.34 0.38 0.47 0.48 0.62 0.62 0.79 0.80 0.97


RFA ¼ Royal Fleet Auxiliary; TLX ¼ Task Load Index; NFR ¼ Need For Recovery. *Variables above the line are significantly related to age.

Table 5. Multiple linear regression analysis of Need For Recovery scale score and work demands for ratings. Variable

Beta

Adjusted R2

Change in R2

NASA TLX frustration Baecke Work Index NASA TLX temporal demands

0.48 0.23 0.14

0.34 0.41 0.42

0.34 0.07 0.02

TLX ¼ Task Load Index.

Table 6. Multiple linear regression analysis of NFR scale score and work demands for officers. Variable NASA TLX frustration NASA TLX performance NASA TLX effort

Beta

Adjusted R2

Change in R2

0.42 70.27 0.23

0.26 0.29 0.33

0.26 0.03 0.04

TLX ¼ Task Load Index.

which was significantly higher (z ¼ 2.78, N – Ties ¼ 103, p 5 0.01) than the median NFR scale score for these same respondents at time point 1 (36.4). As was found at time point 1, officers scored significantly higher on the NFR scale than ratings (median score ¼ 63.6 compared to 36.4, U ¼ 1552, n1 ¼ 83 n2 ¼ 51, p 5 0.01). A median split was conducted on age for each group to allow comparison of NFR scale scores between younger and older personnel. The median ages were 45.8 years in the ratings group and 40.8 years in the officers group. Table 7 shows the median NFR scale scores and the percentage of personnel classified as having high NFR scale scores (36 or above) according to the Dutch norms for the

Table 7. Median NFR scale scores and percentage of personnel with high Need For Recovery (NFR) scale scores for older and younger personnel at time point 2.

Age group

n

Median NFR scale score time point 2

% with high NFR scale score time point 2

Ratings below 45.8 years Ratings above 45.8 years Officers below 40.8 years Officers above 40.8 years

41

36.36

56

42

36.36

57

25

63.63

80

26

50.00

62

scale at time point 2. This is divided into older and younger age groups for ratings and officers respectively. Mann–Whitney U tests showed that there were no significant differences between the NFR scale scores at time point 2 of ratings above and below the median split for age, or between the NFR scale scores at time point 2 of officers above and below the median split for age (U ¼ 803.5, n1 ¼ 41, n2 ¼ 42, p ¼ 0.60, U ¼ 243.5, n1 ¼ 25, n2 ¼ 26, p ¼ 0.12). Change in NFR scale score between the two time points in the same personnel was calculated (time point 2 – time point 1) and the distribution is shown in Figure 1. As can be seen, the distribution is positively skewed, indicating an increasing need for recovery over time. Two stepwise linear regressions were conducted to assess which factors accounted for change in NFR scale score between the two time points in ratings and in officers. The main variables associated with NFR scale score change in both groups were task demands; for ratings the model accounted for 25% of the variance in NFR scale score change and the main associations were found with NASA TLX frustration scale score at time point 1 (17% of the variance in NFR scale score change), and NASA TLX temporal demands scale score at time point 2 (8% of the variance). For officers, the only variable associated with NFR scale score change was change in temporal demands (time pressure) between the two time points on the NASA TLX scale, which accounted for 9% of the variance. 4. 4.1.

Discussion Age and need for recovery

Age was not associated with need for recovery from work. In addition, no evidence was found to suggest that age influenced change in NFR scale score between two time points for officers or ratings. It appears that

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R.S. Bridger et al. associated with NFR scale score than the Baecke index score of habitual physical activity. These findings agree with those of Devereux and Rydstedt (2009), who found that psychological work demands were the stronger risk factor compared to physical work demands in a study population of civilian shore-based workers. It is not surprising that frustration was strongly linked to an elevated NFR scale score if the frustration was carried over into leisure periods as a result of an inability to disengage from the work, because RFA personnel remain in the work environment during their leisure time. According to this argument, the physical constraints of life aboard ship would appear to prevent psychological detachment from work-related frustration, thus impeding recovery from work.


4.3.

Figure 1. Change in need for recovery (NFR) reported between time points 1 and 2 (n ¼ 134).

older workers were able to cope with work demands onboard ship as well as their younger counterparts. This is in contrast to the findings of Akerstedt et al. (2002) and Kiss et al. (2008), both of which found that age was significantly related to need for recovery, albeit in different directions and working populations. Thus, the association between age and need for recovery from work may be specific to the occupation under study. However, a survivor effect may be in operation, whereby personnel who struggle to cope with work at sea leave the organisation, or move into a different area of work where they can cope more easily. Alternatively, it could be that older personnel have developed successful strategies that enable them to cope with the demands of working life onboard a ship as well as younger personnel. 4.2. Factors associated with need for recovery: psychological versus physical demands Whilst need for recovery was not associated with age, other interesting associations did emerge. Need for recovery from work was most strongly related to the reported level of frustration, which indicated discouragement, stress and annoyance experienced on an average day at work. The relationship between this scale and NFR scale score suggests that it is not, on the whole, physical exhaustion that is related to a high need for recovery but rather a stressful or discordant work environment. Even for ratings, who carry out a variety of physical tasks, frustration was more strongly

Accumulation of need for recovery

NFR scale score was significantly higher at the second time point showing that there was a trend towards an accumulation of work-related fatigue over time. However, whilst this increase in need for recovery might suggest a build-up of work-related fatigue in some personnel after serving longer onboard, it could also be due to a bias in the type of personnel responding to the follow-up, i.e. those personnel reporting a greater need for recovery at time point 1 might have been more likely to respond subsequently. This did not seem to be the case, as a comparison of NFR scale scores at time point 1 between those who responded to the follow-up and those who did not revealed no statistically significant differences. Alternatively, it could be a reflection of the difference in data collection technique, as the first NFR scale was administered with the interviewer present and recording the responses for the participant, whereas the follow-up NFR scale was completed by respondents, presumably on their own. The presence of the interviewer at the first NFR scale completion might have influenced participants’ responses. With regard to age-related differences, age did not predict an accumulation of work-related fatigue during RFA ship appointments. Instead, it was found that the main predictors of change in NFR scale score were work demands; namely, frustration and temporal demands. This supports the concept of need for recovery as a state-like characteristic that changes in line with current task demands. 4.4. High need for recovery levels in the Royal Fleet Auxiliary Despite finding that older personnel appeared to be coping with their work demands as well as younger


Ergonomics personnel, many personnel of all ages did report relatively high levels of work-related fatigue. A score of 36 or more on the NFR scale is taken to indicate mild fatigue. The originators of the scale recommend that if more than 50% of a working population scores equal to or above this cut-off point, management interventions may be needed as it could be indicative of a problem at the organisational level. In the current sample, 55% scored 36 or more at the first time point and 62% at the second time point, which suggests that work-related fatigue may require further investigation. Given that this study indicated that a high level of frustration at work was the main factor associated with high need for recovery, it is of some theoretical and also practical interest to consider what might be the causes of frustration in this group. van Veldhoven and Sluiter (2009) developed a scale to measure recovery opportunities at work in relation to work organisation, demonstrating that a lack of opportunity for recovery at work was related to a high need for recovery after work. Such a scale is of enormous value in identifying the kinds of constraints that prevent recovery from demanding work. At the time of the present study, this scale was not available to the authors of the present paper. However, the contents of seven of the nine items on the recovery opportunities scale reflect many of the constraints intrinsic to working life at sea. These include constraints on: interrupting work when necessary; determining the beginning and end of the workday; deciding when to take a break; taking holidays at will; taking days-off at will; freedom to arrange working hours and days off. 4.5. Theoretical considerations Given the importance of psychological work demands in determining need for recovery from work, it is worthwhile to consider the present findings in relation to relevant theory. Frustration may indicate a lack of control over the achievement of work goals; in which case, the finding is in accord with predictions of job stress models, such as that of Karasek and Theorell (1990). Even for ratings, who carry out a variety of physical tasks, frustration was more strongly associated with NFR score than the Baecke index score. It is of some theoretical and also practical interest to consider why a lack of control in the form of frustration of work goals might lead to a high need for recovery from work in this group of seafarers. Psychological detachment from work is thought to be positively related to well-being (Sonnetag and Bayer 2005) in the form of positive mood and low levels of fatigue. Experimental studies on adolescents have demonstrated that when goals are not readily

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attainable, the inability to disengage from goal seeking may produce frustration, leading to exhaustion, rumination, lack of sleep, illness and lowered immunity (Miller and Worsch 2007). Aboard ship, personnel live in their workplace and have fewer options for physical detachment from work. Detachment from work has been shown to have cognitive benefits (Berman et al. 2008), specifically recovery of directed attention ability. However, these benefits accrue only when the work environment is left for an environment in which the demands on attention are low (thus, recovery occurred after a walk in an arboretum in Berman et al.’ s (2008) study, but not after a walk of the same duration in busy city streets). Self-control, an aspect of self regulation important for resisting sudden impulses, resisting distraction and overcoming inner resistance (reluctance to carry out a task), is known to be a limited resource (Galliot et al. 2007). Activities that place high demands on selfregulatory resources will deplete the capacity to carry out further tasks with similar self-regulatory demands (irrespective of the specific nature of the following task). This depletion of self-regulatory resources by frustration of work goals and the failure to recover after work is reflected in the responses to several of the items on the NFR scale. Positive responses to some of the items on the NFR scale are symptomatic of lowered self-regulatory strength (e.g. having problems concentrating, difficulties showing interest in others, wanting to be left alone and having difficulty initiating other activities). According to this argument, the physical constraints of life aboard ship would appear to prevent psychological detachment from work-related goal-seeking, thus impeding recovery from work. Other researchers have found that the inability to detach from work, which could lead to high need for recovery, is associated with chronic exposure to time pressure and hours worked on the day that detachment was measured (Sonnetag and Bayer 2005). In the RFA, some personnel work a repeating ‘4 h on; 8 h off’ watch at sea and normal daytime work hours when alongside. Thus, work hours are relatively fixed by the watch system. Taken together, these findings suggest that the lack of opportunity for disengagement from work will place high self-regulatory demands on personnel working on ships (and, very likely, personnel working in polar stations over winter, during long space flights, etc.). Inability to cope with these demands, as indicated by a high need for recovery, is likely to lead to health problems in the long term. An ergonomic approach to workplace design under these constraints would be to increase the opportunities for disengagement, for example, though the use of better gym and leisure facilities, improved Internet access, etc.

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R.S. Bridger et al. Limitations


Despite attempts to encourage participation in this study through the use of interview timetables and promotion of the study’s purpose and applicability, participation was still voluntary and dependent upon personnel taking time out of their working day in order to take part. Thus, the participation rate was not high. This was a foreseen drawback of conducting the interviews in the field onboard active RFA ships rather than on shore directly before or after leave periods. However, the benefits of capturing fatigue data during real appointments onboard ships outweighed the problem of potentially lowered participation rates. A related issue of conducting the interviews onboard active ships was that the sample could not be stratified by age, as the interviewers were granted access to the ships but did not have control over the demographics of personnel serving onboard. 5. Conclusions Older personnel did not have a higher need for recovery after work than younger personnel in the RFA. This may be due to a survivor effect, in which older personnel who cannot cope either leave the service or are medically retired. In line with previous research, psychological work demands were found to have a stronger relationship with need for recovery than physical demands. In this study, the psychological demand that emerged as having the strongest correlation with need for recovery was frustration at work. The causes of this frustration were not known but may merit further investigation. Need for recovery was higher in the same personnel at a later time point on their work appointment onboard. This suggests that work-related fatigue did accumulate over time when work demands did not cease. Finally, need for recovery levels in the RFA as a whole did indicate a relatively high level of workrelated fatigue at the organisational level, which may suggest the need for management interventions. References Akerstedt, T., et al., 2002. Work load and work hours in relation to disturbed sleep and fatigue in a large representative sample. Journal of Psychosomatic Research, 53 (1), 585–588. Baecke, J.A.H., Burema, J., and Frijters, E.R., 1982. A short questionnaire for the measurement of habitual physical activity in epidemiological studies. American Journal of Clinical Nutrition, 36, 936–942. Berman, M.G., Jonides, J., and Kaplan, S., 2008. The cognitive benefits of interacting with nature. Psychological Science, 18, 1207–1211.

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Wadsworth, E.J., et al., 2008. Fatigue and health in a seafaring population. Occupational Medicine, 58, 198– 204. Welford, A.T., 1958. Ageing and human skill. Oxford, UK: The Nuffield Foundation, Oxford University Press. Wertheim, A., 1998. Working on a moving platform. Ergonomics, 41, 1845–1858.