A pilot study: Exploring the musculoskeletal risk exposure associated with drying laundry using the public housing pipe-socket system amongst women in Singapore

Abstract

BACKGROUND:

The biomechanics of homemakers has been minimally studied. The way laundry-drying is performed in Singapore public-housing, using the pipe-socket-system (PSS), could expose the homemakers to musculoskeletal disorder risk.

OBJECTIVE:

This study aims to quantify the musculoskeletal risk exposure (MRE) associated with laundry-drying amongst female homemakers using the PSS in Singapore public-housing.

METHODS:

Using snowball sampling approach, five female homemakers familiar with the described laundry-drying method were recruited. The postures of the participants were analysed from video-recorded data and scored using the Rapid Entire Body Assessment (REBA).

RESULTS:

This pilot study revealed very strong evidence (p = 0.001) that the participants were exposed to medium risk (REBA score 4.3) when performing this housework task.

CONCLUSIONS:

Extreme awkward postures and repetitive motions were observed from the participants during the analysis. High REBA scores were frequently associated with the awkward postures adopted due to constraints of physical work space.

Keywords

Ergonomics homemakers housework biomechanical risk biomechanics

1 Introduction

Musculoskeletal disorders (MSD) are one of the most prevalent medical conditions in current society affecting people from various paid and unpaid occupations [1]. Homemakers make up a large proportion of the MSD affected population and are minimally studied in the area of ergonomics and occupational health [2, 3]. Literature describes a homemaker as a person who manages the housework at home [2 –5]. Housework is regarded as a regular form of manual work, involves routine to perform compulsory household maintenance tasks that require substantial physical labour [4]. Apostoli, Sala [3] considered the physical labour in housework to entail light to moderate biomechanical loads that could contribute to the worsening of MSD.

A recent study conducted in an outpatient occupational therapy hand clinic in a Singapore hospital, discovered that homemakers made up 20.1% of the total upper limb (UL) MSD cases referred to the Occupational Therapy (OT) Department [6]. In view of this large proportion, there is a need to identify if external factors in housework increase the musculoskeletal risk exposure (MRE), leading to increased harm to the biomechanics of the homemakers [3 , 7–9].

The prevalence of MSD in homemakers is high in all studies shown thus far. These studies were conducted with populations from Bangladesh, Hong Kong, Italy and the Lebanon [1–3 , 11]. The varieties of housework tasks explored were limited. Performing different housework activities varies in the set of body mechanics required, and the expectation of the same housework could vary in different cultural context. Hence, the MRE for one housework task should not be over-generalised to other forms of housework and amongst different cultures and context [3, 5]. For accurate and relevant MRE analysis it is important to define and examine the identified housework activity and subtasks performed by the homemakers in their cultural context [5].

Singapore has a population of 5.39 million [12] and characterised by a warm climate with limited open space for drying washed clothes. As the use of tumbler dryers is uncommon, the local practice is to hang the laundry on long bamboo poles out from the kitchen windows to dry [13]. This unique way of drying laundry involves lifting a bamboo pole, filled with partially wet clothes, while leaning out of the window to secure the bamboo pole onto the pipe-socket-system (PSS) (Fig. 1). Although the Singapore government made initiatives to improve older public housing flats with newer pipe-sockets devices [14], the public are still required to put the laundry out from the window for drying [15]. It is believed that such action could increase the MRE of homemakers in Singapore.

Fig.1

Picture illustration of laundry-drying using the PSS in Singapore public housing.

With 82% of the Singapore population residing in public-housing [12], analysing the MRE in laundry-drying using the PSS would be an appropriate and culturally relevant housework task analysis. With no previous study analysing this form of housework, identification of the MRE for this specific aspect of the laundry-drying activity would be the requisite for accurate consultation for the affected homemaker population residing in Singapore [3].

As 99.1% of the homemaker population in Singapore are females [6], the primary aim of this study is to identify the MRE associated with laundry-drying amongst females living in Singapore public-housing using the PSS. It was hypothesised that Singapore women residing in public-housing are exposed to musculoskeletal risk when performing laundry-drying using the PSS. The secondary aim of this study is to identify postures and factors that contribute to risk in MRE.

2 Methodology

An observational approach using digital video-recording was chosen as the most appropriate method for data collection for this study. Observation is the most direct way to gather information on the biomechanical demands of the homemakers and avoids using less reliable memory recall [16 –18]. Ethical approval was obtained from the College of Health and Social Care at Brunel University UK and SingHealth Research Ethics committees.

2.1 Participants

Participants were recruited through the staff from the occupational therapy department in an acute hospital in Singapore using snowball sampling. Marras [7] reported that the height of an individual could affect the lever system of the body, especially when the task involves trunk bending motion. With trunk flexion likely to be involved in the laundry-drying activity, the height range of the participants was controlled. The average height of a Singaporean woman is 160 cm [19]. The inclusion criteria therefore restricted the height range of healthy female participants from 155 cm to 165 cm, living in Singapore public-housing and those familiar in completing laundry-drying using the PSS. Pregnant women, or those diagnosed with any form of MSD and currently seeking medical treatment, were excluded from the study to prevent aggravation of their existing condition.

2.2 The setting

The video-observation was conducted in the home of the participants for the experience of realism [20].This enabled greater ease for the participants in comparison to completing the laundry-drying housework in a new environment [17, 21]. Highlighted by previous authors, one of the risk factors which may affect the biomechanics of the homemakers when performing housework is the structural layout of the house [2, 5]. For this reason, conducting the observation session in the house of the participant would allow for this potential factor to be observed.

2.3 Potential variables in the study and controls taken

The potential variables in this study including the length of the bamboo pole, the type and the material of the laundry, and the weight of the laundry were controlled to ensure a standardised and accurate study. The choice of the quantity and types of clothes, and bamboo poles used in this study were made in accordance to the Singapore statistics. The potential variables and controls taken are summarised in Table 1.

Table 1
Potential variables identified and controls taken

Potential variables Controls to limit the variables

•Variable number of clothing washed and the material of clothes •12 cotton tee-shirts and 12 pairs of jeans.

•Weight of laundry load •To pre-determine laundry load by washing the laundry in a 1000 RPM spin speed washing machine for 30 minutes.

•(wet and dry) •Laundry load of 2 pairs of jeans and 2 cotton tee-shirts (wet and dry) with 8 clothes pegs hung on a bamboo pole were separately weighed on a portable digital weight scale to determine and standardise the laundry load.

•Wet laundry load: 1.38 kilograms, Dry laundry: 1.03 kilograms.

•Length of bamboo pole •6 bamboo poles of equal length (Length: 1.5 m; standard diameter 2.5 cm).

Potential variables	Controls to limit the variables
•Variable number of clothing washed and the material of clothes	•12 cotton tee-shirts and 12 pairs of jeans.
•Weight of laundry load	•To pre-determine laundry load by washing the laundry in a 1000 RPM spin speed washing machine for 30 minutes.
•(wet and dry)	•Laundry load of 2 pairs of jeans and 2 cotton tee-shirts (wet and dry) with 8 clothes pegs hung on a bamboo pole were separately weighed on a portable digital weight scale to determine and standardise the laundry load.
	•Wet laundry load: 1.38 kilograms, Dry laundry: 1.03 kilograms.
•Length of bamboo pole	•6 bamboo poles of equal length (Length: 1.5 m; standard diameter 2.5 cm).

No problem was found in the equipment and tools planned for this study except for the length of the bamboo poles. Issues with the length of the bamboo poles are elaborated in Section 2.5.

2.4 Identification of subtasks included for analysis

The laundry-drying activity was first identified to have seven subtasks for observation and analysis (Table 2). This increased to nine subtasks for observation and analysis after conducting the pilot video practice observation with the first participant due to possible variations of practice among participants (elaborated in Section 2.5).

Table 2
Nine subtasks identified for analysis from the video-observation

Subtask Number Subtasks Title

1^* Retrieving pole from overhead rack

2 Retrieving pole (lean against wall)

3 Retrieving partially wet laundry to place onto pole

4 Securing laundry with clothes pegs

5 Putting pole out with partially wet laundry

6 Bringing pole in with dry laundry

7 Removing dry laundry from pole

8^* Returning pole to overhead rack

9 Returning pole (lean against wall)

Subtask Number	Subtasks Title
1^*	Retrieving pole from overhead rack
2	Retrieving pole (lean against wall)
3	Retrieving partially wet laundry to place onto pole
4	Securing laundry with clothes pegs
5	Putting pole out with partially wet laundry
6	Bringing pole in with dry laundry
7	Removing dry laundry from pole
8^*	Returning pole to overhead rack
9	Returning pole (lean against wall)

Note: 1. Subtask [2] to [7] & [9] were performed using the 1.5 m bamboo pole prepared by the researchers. 2. ^*Subtask [1*] & [8*] performed by 3 out of 5 participants (one repetition per participant) using their own bamboo poles. 1st recruited video-practice participant & participant who did not own an overhead-rack did not perform subtask [1*] & [8*].

2.5 Pilot video-practice observation

After ethics approval from both institutions were gained, a trial observation was conducted with the first recruited participant. The purpose of this observation was to ensure smooth running during the actual data collection with logistic issues sorted [15, 20].

It was realised that the length of the bamboo poles owned by the participants varied from 2.07 m to 2.80 m. For better understanding, Fig. 2 features a typical overhead-rack in a typical laundry area of Singapore public-housing. However, as the researchers were unable to ascertain the bamboo pole length owned by their next few participants at the time of the practice session, a grade-down from the first subtask was made. Instead of retrieving the pole from the overhead-rack, the participant retrieved the bamboo pole placed leaned against a wall. This was not considered a complete modification to the laundry-drying task, as poles would usually be placed against the wall prior proceeding to the next subtask – ‘retrieving partially wet laundry to place onto bamboo pole’.

Fig.2

Overhead racks in a typical Singapore public-housing.

As the video-recording quality of the video-practice observation was deemed sufficient and with no major modifications made from the original plan, the video-practice observation was included as formal data for the Rapid Entire Body Assessment (REBA) scoring.

Following the practice observation, it was decided that if the 1.5 m bamboo pole prepared by the researchers could not fit onto the overhead-racks in other participants’ house, the laundry activity would commence from subtask 2; ‘retrieving the bamboo poles placed leaned against a wall’ (using the standardised 1.5 m bamboo pole), instead of subtask 1; ‘retrieving bamboo pole from the overhead rack’. For analysis purpose, the participants were requested to retrieve the bamboo pole from the overhead-rack using their own bamboo pole, if agreeable. With that, the original 7 subtasks identified for analysis increased to 9, as listed in Table 2.

2.6 Data collection

The REBA was the most suitable postural assessment tool for this laundry-drying housework activity that is performed in a standing posture. The REBA analyses the entire body posture, provides clear indication on considerations for high repetitive motions and awkward postures, indicates the risk exposure level, provides a quantifiable score to indicate the MRE for the analysed posture, and recommendation for the urgency of change for the assessed posture. The REBA is thus chosen as the ergonomics assessment tool for this study as it meets the biomechanical demands of the laundry-drying task, and is within the resources available for this research. The REBA had shown good indications for inter-observer reliability [22], validity, and is sensitive in detecting changes or improvements following ergonomics intervention [23]. The REBA is also widely used internationally and considered to present generalisable results within the context of a full ergonomics workplace assessment [22].

2.7 Data analysis

To answer the primary aim, the mean REBA scores from the total number of analysed postures of all the participants were taken. This calculated mean REBA score was compared against the REBA table to establish the overall MRE level for this laundry-drying activity.

The average REBA scores for each subtask from all the participants enabled the highest and lowest averaged REBA score within the laundry-drying activity to be identified. Additionally, within each participant, the average REBA scores for each bamboo pole completion was accounted for. This enabled for any trend in the REBA score for each completed laundry-drying task to be realised.

Hypothesis testing was conducted to confirm if there is significant difference between the average REBA scores of the participants in this pilot study and the REBA score which indicates no risk in MRE [24]. In REBA, a score of two and above indicated a risk in MRE [22]. With that, for statistical analysis in this study, a REBA score of below two formed the set of value which indicated no MRE for women performing laundry-drying using the PSS in Singapore public-housing.

This pilot study took 95% CI to estimate the reliability of the result. A p-value of ≤0.05 would be considered the difference in REBA score to be statistically significant in this study. The Statistical Package for the Social Sciences (SPSS) version 20 was used to manage the study data.

Observations from the video-analysis were analysed, using descriptive analysis with guidance from the REBA, to identify the postures and factors that contribute to the risk in MRE. The REBA considered a task to have high repetitions when the repeated action happened more than 4 times per minute, or the participant assumed an awkward posture which causes a rapid large change in the posture range or having an unstable base.

3 Results

All five participants (A, B, C, D and E) recruited were right hand dominant. They had a mean age of 41 years (SD = 14.32), height of 1.56 m (SD = 1.00), 63 kg (SD = 13.13) in weight, and a body mass index (BMI) of 25.8 (SD = 5.22).

Due to variations in practice among participants, there is variation in the subtasks included in the analysis of each participant. Based on analysis of these subtasks, the overall MRE level of laundry activity was determined and specific subtasks with the highest and lowest MRE level were identified. The authors also conducted analysis on MRE level variations among subtasks across participants and within each participant.

Despite the variation in practice observed among participants, the only subtasks that were not observed in all the participants are subtask 1 (retrieve poles from overhead rack) and 8 (returning of poles onto overhead rack). Three out of five participants (B, C, and E) retrieved the bamboo poles from the overhead-racks, placed the poles against a wall, and returned the bamboo poles back to the over-head rack once finished. While participant A recruited for the pilot video practice was not invited by the researchers to perform these subtasks, participant D did not have an overhead-rack in the house. The postures of the three participants who demonstrated retrieving and returning the bamboo poles to the overhead-rack were scored separately. This variation in the ways to retrieve and return the bamboo poles had allowed for further comparisons in the REBA scoring of the postures to be made. Table 3 summarised the subtask included for analysis for each participant.

Table 3
Task included for analysis for each participant

Participant Subtask

1^* 2 3 4 5 6 7 8^* 9

A √ √ √ √ √ √ √

B √ √ √ √ √ √ √ √ √

C √ √ √ √ √ √ √ √ √

D √ √ √ √ √ √ √

E √ √ √ √ √ √ √ √ √

Participant	Subtask
A		√	√	√	√	√	√		√
B	√	√	√	√	√	√	√	√	√
C	√	√	√	√	√	√	√	√	√
D		√	√	√	√	√	√		√
E	√	√	√	√	√	√	√	√	√

Subtask 1: Retrieving pole from overhead rack; Subtask 2: Retrieving pole (lean against wall); Subtask 3: Retrieving partially wet laundry to place onto pole; Subtask 4: Securing laundry with clothes pegs; Subtask 5: Putting pole out with partially wet laundry; Subtask 6: Bringing pole in with dry laundry; Subtask 7: Removing dry laundry from pole; Subtask 8: Returning pole to overhead rack; Subtask 9: Returning pole (lean against wall). 1. Subtask [2] to [7] & [9] were performed using the 1.5 m bamboo pole prepared by the researchers. 2. ^*Subtask [1*] & [8*] performed by 3 out of 5 participants (one repetition per participant) using their own bamboo poles. 1st recruited video-practice participant & participant who did not own an overhead-rack did not perform subtask [1*] & [8*].

One uncommon practice was identified and excluded during the calculation of the average REBA score for the laundry drying activity. Participant D reported that she would usually store the bamboo poles flat on the floor when not in-use, since she did not have an overhead rack. She would bring the poles to a standing position (leaning against a wall) to commence the laundry-drying activity and ended the task by leaving the bamboo poles on the ground each time. As participant D did not meet the standardised description of ‘keeping the pole leaned against a wall’, REBA analysis for participant D only commenced from the point when she brought the pole to a standing position to commence laundry-drying activity (subtask 2) and ended at removing the dry laundry from pole (subtask 7).

3.1 MRE level in the laundry activity

The participants scored an average REBA score of 4.3 (SD = 0.50) in the laundry-drying assessment based on analysis of subtasks 2–7, and 9. The average REBA score of the participants rose to 5.4 (SD = 0.71) when subtasks 1 (Retrieve pole from overhead rack), and 8 (Return pole onto overhead rack) were included in the analysis. Nevertheless, REBA scores of 4.3 and 5.4 corresponded with a medium risk in MRE according to the REBA scoring table respectively [22]. This study revealed that women in Singapore performing laundry-drying using the PSS were exposed to medium risk in MRE. A one-sample t test revealed that the average REBA scores in laundry-drying carried out by the current sample (n = 5, mean = 4.3, SD = 0.5) is significantly higher than the safe value of 2 despite variations in methods [t(4) = 10.29, p = 0.001], with 95% CI [1.69, 2.92]. This indicated preliminary evidence (p≤0.01) that women in Singapore performing laundry-drying using the PSS were exposed to musculoskeletal risk.

Table 4 summarised the average REBA scores for each of the analysed subtasks. This highlighted the awkward and extreme postures, and high repetitions performed by the participants during the laundry-drying housework. Retrieval and returning of the bamboo poles to the overhead-racks (subtasks 1* and 8*) scored the highest in REBA scores amongst the subtasks, and ‘placing the bamboo pole back leaned against the wall’ (subtasks 9) was ranked the lowest in MRE amongst the subtasks (refer to Table 4).

Table 4
Summary of average REBA scores for each subtask & awkward/extreme posture & high repetitions of each participants

Subtask 1^* 2 3 4 5 6 7 8^* 9

Average REBA Scores 6.7 2.5 4.8 3 6.4 5.1 5.5 6.7 2.3

Trunk

Flexion p,r p p p

Extension p p

Twisting r p p,r

Knee

Flexion r p, r

Extension r r

Toes

Tip Toe p p

Unstable base p p p p

Neck

Flexion r p, r p

Extension p,r r p,r

Twisting

Shoulder

Elevation p,r p,r p,r p,r p,r p,r

Abduction r p,r p,r p p,r

Flexion r p,r r p,r

Elbow

Flexion p

Extension p

Forearm

supination-pronation r

Wrist

Flexion p,r

Extension p,r

Ulna deviation p,r

Thumb/Fingers

Pinching r

Subtask	1^*	2	3	4	5	6	7	8^*	9
Average REBA Scores	6.7	2.5	4.8	3	6.4	5.1	5.5	6.7	2.3
Trunk
Flexion			p,r		p	p	p
Extension	p							p
Twisting				r	p		p,r
Knee
Flexion			r				p, r
Extension			r				r
Toes
Tip Toe	p							p
Unstable base	p				p	p		p
Neck
Flexion	r				p, r	p
Extension	p,r				r			p,r
Twisting
Shoulder
Elevation	p,r			p,r	p,r	p,r	p,r	p,r
Abduction	r			p,r	p,r	p	p,r
Flexion	r			p,r	r		p,r
Elbow
Flexion							p
Extension							p
Forearm
supination-pronation				r
Wrist
Flexion				p,r
Extension				p,r
Ulna deviation				p,r
Thumb/Fingers
Pinching				r

p - awkward and extreme posture. r- repetition (more than 4 times per minute).

Comparing the average REBA score per bamboo pole completion within each participant (Fig. 3), three out of five participants scored the highest average REBA score when performing laundry-drying for bamboo pole number three (participant A, C and D).

Fig.3

Within participant comparison of REBA score per bamboo.

3.2 Postures and factors that contribute to risk in MRE

Certain postures were observed in this study that might likely lead to MSD or cause safety issue due to awkward postures and high repetitions in motion. Some are caused by the constraint in the workspace of the participants.

The body regions observed to be in extreme and/or awkward postures in this laundry-drying housework were the neck (forward flexion and twisting), trunk (forward bending and twisting), shoulder (extreme flexion, elevated, and abducted) and, the wrist (flexion and ulnarly deviated). Trunk twisting, knee flexion, wrist flexion with ulnar deviation, and thumb pinch motions were performed in repetitive motions (more than four times per minute) especially in the subtasks 3, 4, and 7. Repetitive motions of neck and shoulder were also observed when participants performed subtasks 1, 5, 6 and 8. The stooped posture (trunk flexion with knee bent) was adopted by the participants during subtasks 3 (retrieving partially wet laundry to place onto pole) and 7 (removing dry laundry from bamboo poles). Tripod and power grasp pinch were the two common repetitive actions adopted by the participants to manipulate the clothes pegs. Tip-toeing was observed when one of the participants attempted to reach for the bamboo poles on the overhead-rack without the use of an assistive stick, and when participants attempted to reach forward to retrieve the bamboo poles to put the laundry in and/or out of the window.

Participants were observed to assume a more non-neutral posture and the MRE for a subtask peaked when participants were constrained by the physical layout of the house. Observations included narrow workspace and/or workspace blocked by the washing machine when attempting to bring the bamboo poles in and out of the window. Also, participants tend to increase trunk flexion/twisting, knee bending, and elbow flexion/extension when they were required to work further away from a task. This increase in distance between the participants and the work task led to higher REBA scorings. This observation pattern could be clearly observed in the postural variations in subtask 7 (removing of dry laundry from the bamboo poles). The REBA scores for subtask 7 ranged from ‘10’ indicating high risk to ‘1’ indicating negligible risk. This wide range in scores was due to the varied ways participants removed the laundry from the bamboo poles. When participants placed the dry laundry on the top surface of a washing machine or on a high chair, the participants were seen in a less stooped posture (less trunk flexion/twisting and knee flexion), in comparison to bringing the laundry to a pail placed on floor level. The participants generally demonstrated four ways in the removal of laundry illustrated in Fig. 4. The difference in the REBA scores for this activity was mainly affected by the degree of shoulder flexion and abduction range 30° to 90°, trunk flexion range approximately 10° to 50°, and knee flexion range approximately 10° to 80°. It was also observed that when the participant was restricted by her physical environment and required the additional inches to reach for the target object, a single-leg forward unstable bending posture was assumed.

Fig.4

Postural variations in removing dry laundry from bamboo poles.

4 Discussion

The average REBA scores suggested that women in Singapore experienced medium level of MRE in performing this laundry-drying housework. The calculated medium risk MRE level in this study coincided with the light to moderate MRE level in other housework activities assessed by Apostoli et al. [3] and the mild to moderate MSD discomfort level in Hong Kong homemakers in the Fong and Law [2] study. From the study, it was realised that laundry-drying is a housework that could be performed in varied patterns of motion. These variations appeared to influence the MRE of the participants in the laundry-drying activity. This observation is in line with the study conducted by Habib et al. [10] and Apostoli et al. [3] who concluded that the MRE of housework were influenced by the working styles adopted by the individual homemaker.

In this study, certain body regions were observed to be susceptible to high MRE either due to high repetitions or awkward postures. These body parts mirrored the body regions affected by the homemaker participants in the studies of previous authors [1–3 , 10].

As mentioned in the above results, observations of repetitive motion of the shoulder in extreme flexion, abduction and/or overhead movement are often associated with shoulder overuse conditions such as rotator cuff tendinitis and shoulder impingement syndrome [26, 27]. The combination of neck flexion with shoulder elevation or flexion movement could increase the likelihood for tension neck syndrome [27 –29]. The repetitive postures described were assumed by the participants when performing subtasks 4–8.

The observed wrist flexion with ulnar deviation, as well as repeatedly forearm pronation, and thumb pinching actions performed by the participants in subtask 4 (securing the laundry with clothes pegs) could potentially lead to certain MSD conditions, as suggested based on findings from previous studies [30 –34]. The MSDs included: (1) Carpal Tunnel Syndrome (CTS) from increase carpal tunnel pressure which could cause ischemia of the median nerve [33, 34]; (2) De Quervain’s tenosynovitis / tendonitis from repeated wrist ulnar deviation and thumb pinch motion causing inflammation of the abductor pollicis longus and extensor pollicis brevis tendons in the first dorsal compartment of the wrist; and (3) trigger thumb from the repetitive clothes pegs pinching motions [31, 32]. In the forearm, repeated pronation-supination actions could cause medial and lateral epicondylitis [30 , 33].

The stopped postures observed in certain subtasks in this study were likely to increase risk for low-back pain (LBP) symptoms. LBP was rated as one of the highest reported MSD symptoms in homemakers [1 , 11].

Participants were noted to demonstrate unstable postures, such as tip-toeing and standing on single foot while performing the laundry tasks. These imbalance stances could reduce the overall balance of the participants [35], leading to increase injury, including fatalities when performing the laundry-drying housework. The Singapore Ministry of Manpower Manpower [36] and newspaper articles have reported homemakers losing their lives during laundry-drying task due to a loss of balance and falling from a height [37 –39].

In the present study, workspace was found to be one of the factors that impact on postures adopted by the participants while they perform different subtasks. Participants are more likely to adopt awkward postures when they are working further away from the task. This observation pattern could be clearly observed in the postural variations in the ‘removing of dry laundry from the bamboo poles’ (subtask 7). The increase in distance between the participants and the work task appeared to lead to higher REBA scorings. This observation was consistent with the ergonomics theory and studies that examined the postures of participants in the various zones of convenient reach (ZCR). According to the ZCR theory and proven in ergonomics industrial studies, individuals employed a more relax posture with less postural exertion when an object is situated in closer proximity to them [40 –43].

It was observed that MRE often peaked when a participant worked in a narrow workspace. This observation aligned with and added strength to previous research findings by Fong and Law [2] and Habib, Fathallah [5]. These authors postulated that homemakers adopted awkward postures to accommodate to the housing structural layout, which could increase their MRE in the performance of housework activity. In the Fong and Law [2] study, the authors suggested the association between the participants’ MSD symptoms and washing of utensils was due to the low sink height in Hong Kong housing estates. In the Habib, Fathallah [5] study, the authors associated the space constraint in the home environment with the awkward postures assumed by the homemakers during housework performance, which led the homemakers to experience MSD symptoms. The results from this study also concurred with Nordander, Ohlsson [44] that a constrained work environment elevates MSD risk.

It was recognised that the average REBA score for each repetition peaked during the third repetition of bamboo poles placement (three out of five participants) of laundry-drying activity. This could be interpreted that the participant may have experienced muscle fatigue of the involved muscles by the third or fourth repetition when performing the laundry-drying housework.

With the reduction in functional capacity of the muscle, the participants compensated their movement with increased trunk twisting and/or shoulder elevation and abduction motions. This interpretation led to a similar conclusion as previous studies that muscle fatigue without taking necessary rest breaks could place the fatigued individual at a greater risk for musculoskeletal injuries [45 –47].

4.1 Limitations

A bigger sample size is recommended for future study as this present study is limited by its small sample size. The cross-sectional design in this study also limited the possibility of establishing causal relationship between the postures of the homemakers with specific MSD conditions. A future study could consider validating findings from this pilot study in a research lab setting using movement analysis system and the electromyography (EMG) to collect data on actual repetitions, muscle loading, and duration of awkward static postures.

The overt video-recording observation method adopted in this study could introduce the Hawthorne reactive effect (observer effect) to the study [48, 49]. The Hawthorne reactive effect may have influenced the participants to respond by intentionally performing the laundry-drying activity in a perceived to be correct (or incorrect) manner to meet (or not meet) the objective of the study.

All the postures from the video-recorded data selected for analysis and REBA scorings of the participants were conducted solely by the primary researcher of the study. This could be viewed as both an advantage and limitation to the reliability of the study. The intra-rater and inter-rater reliability of assessors in visual postural assessment has been established with intra-rater assessment showing high consistency in comparison to inter-rater assessment Fedorak, Ashworth [50].

4.2 Implications

With the results from this pilot study, specific housework related MSD precaution strategies could be derived. Incorporating principles of hierarchy of risk control (HRC) [51 –53] for homemakers could maximise the prevention of MSD related to this laundry activity.

The best way to control a risk is to eliminate the risk completely [52]. It is however, not practical to advise homemakers to stop performing (eliminate) laundry-drying activity completely due to the medium MRE level. Findings from this pilot study however provided some potential directions to assist the homemakers in formulating other modes of MRE control strategies. Potential strategies included substituting higher MRE subtasks with a lower MRE subtask, reorganisation of work space, and adopting work-rest strategies. Potential identified strategies are summarised in Table 5. Future research could consider evaluating the effectiveness of the MSD preventive strategies using the HRC principles, with a pre- and post-intervention comparison study on the homemakers.

Table 5
Hierarchy of Risk Control with Laundry-drying Housework Specific Examples

Hierarchy of Control Laundry-drying Housework Specific Examples

Level 1 Elimination Not practical in the short-term.

The most effective control measure involves eliminating the hazardous manual task and its associated risk. Redesign the job or substitute a substance so that the hazard is removed or eliminated

Level 2 Substitution •Substituting subtasks “retrieving/returning the bamboo poles from/to the overhead-racks” with “retrieving/returning the bamboo poles from/to leaning against the wall” to lessen risk from a high/medium risk to a medium/low risk.

If it is not reasonably practicable to eliminate the risk, then you must minimise the risks so far as is reasonably practicable by: Substitute the hazard with something that gives rise to a lesser risk •Substituting “retrieving/returning the bamboo poles from/to the overhead-racks” with the use of an assistive stick (medium risk) instead of bringing the shoulder to full flexion and tip-toeing to reach for/return the poles (high risk).

Isolation

Isolating the hazard from any person exposed to it

Engineering •Re-organisation of kitchen work-space using the principle of Zones of Convenient Reach [42].

Implementing engineering controls. •Chaput’s principle of manual handling relating to load application to adapt for a lower risk physical handling technique (Chaput, 2003).

Level 3 Administrative •Work-rest strategies to encourage for short rest breaks in between task to prevent muscle fatigue [5].

If there is a remaining risk, it must be minimised so far as is reasonably practicable by implementing administrative controls, and if a risk still remains, then suitable personal protective equipment must be provided and used. Identifying and implementing the procedures you need to work safely. For example: reducing the time workers are exposed to hazards (eg by job rotation) •Consider taking short rest-break after performing every 2 repetitions of laundry-drying task, to prevent muscular fatigue to peak at the 3rd or 4th repetitions.

Personal Protective Equipment

Only after all the previous measures have been tried and found ineffective in controlling risks to a reasonably practicable level, must personal protective equipment (PPE) be used.

	Hierarchy of Control	Laundry-drying Housework Specific Examples
Level 1	Elimination	Not practical in the short-term.
The most effective control measure involves eliminating the hazardous manual task and its associated risk.	Redesign the job or substitute a substance so that the hazard is removed or eliminated
Level 2	Substitution	•Substituting subtasks “retrieving/returning the bamboo poles from/to the overhead-racks” with “retrieving/returning the bamboo poles from/to leaning against the wall” to lessen risk from a high/medium risk to a medium/low risk.
If it is not reasonably practicable to eliminate the risk, then you must minimise the risks so far as is reasonably practicable by:	Substitute the hazard with something that gives rise to a lesser risk	•Substituting “retrieving/returning the bamboo poles from/to the overhead-racks” with the use of an assistive stick (medium risk) instead of bringing the shoulder to full flexion and tip-toeing to reach for/return the poles (high risk).
	Isolation
	Isolating the hazard from any person exposed to it
	Engineering	•Re-organisation of kitchen work-space using the principle of Zones of Convenient Reach [42].
	Implementing engineering controls.	•Chaput’s principle of manual handling relating to load application to adapt for a lower risk physical handling technique (Chaput, 2003).
Level 3	Administrative	•Work-rest strategies to encourage for short rest breaks in between task to prevent muscle fatigue [5].
If there is a remaining risk, it must be minimised so far as is reasonably practicable by implementing administrative controls, and if a risk still remains, then suitable personal protective equipment must be provided and used.	Identifying and implementing the procedures you need to work safely. For example: reducing the time workers are exposed to hazards (eg by job rotation)	•Consider taking short rest-break after performing every 2 repetitions of laundry-drying task, to prevent muscular fatigue to peak at the 3rd or 4th repetitions.
	Personal Protective Equipment
	Only after all the previous measures have been tried and found ineffective in controlling risks to a reasonably practicable level, must personal protective equipment (PPE) be used.

^*Adopted from Workplace Health and Safety Queensland (2011).

5 Conclusion

This study revealed very strong evidence (p = 0.001) that women performing laundry-drying using the PSS were exposed to medium MRE. The two subtasks of retrieving and returning the bamboo poles to the overhead racks were ranked the highest in REBA score. The other subtasks that ranked high in REBA scores were “putting the bamboo poles out with partially wet laundry” and “removing the dry laundry from the poles”. Extreme awkward postures of the neck, UL and the trunk; with repetitive trunk flexion and twisting, knee flexion, wrist flexion with ulnar deviation and thumb pinching motions were observed in the overall laundry-drying housework. Within each subtask, the maximum REBA scores were frequently associated with awkward postures adopted by participants due to constraint physical work space. Also, the participants demonstrated a varied pattern in motion to complete the same task. These variations affected the MRE of the participant for the subtasks.

This is the first biomechanical study that explore the MRE of laundry-related housework and the first to study the biomechanics of the Singapore homemaker population. This study contributes to the literature exploring housework and MRE including the evaluation of various subtasks within a selected housework activity. Such evaluations increase the comprehension of MRE in the identified housework, enabling clinicians to potentially provide more effective preventive intervention strategies to homemakers during consultation. This study provides quantitative concrete evidence on the positive association between the physical work environment of the homemakers and their MRE. Previous studies did not objectively establish association between the MRE with the physical work environment of the homemaker participants.

Conflict of interest

None to report.

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A pilot study: Exploring the musculoskeletal risk exposure associated with drying laundry using the public housing pipe-socket system amongst women in Singapore

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1 Introduction

2.1 Participants

2.2 The setting

2.3 Potential variables in the study and controls taken

2.7 Data analysis

3 Results

Table 3 Task included for analysis for each participant Participant Subtask 1* 2 3 4 5 6 7 8* 9 A √ √ √ √ √ √ √ B √ √ √ √ √ √ √ √ √ C √ √ √ √ √ √ √ √ √ D √ √ √ √ √ √ √ E √ √ √ √ √ √ √ √ √

4.1 Limitations

4.2 Implications

Conflict of interest

References

Table 3
Task included for analysis for each participant

Participant Subtask

1^* 2 3 4 5 6 7 8^* 9

A √ √ √ √ √ √ √

B √ √ √ √ √ √ √ √ √

C √ √ √ √ √ √ √ √ √

D √ √ √ √ √ √ √

E √ √ √ √ √ √ √ √ √