Effectiveness of the multidimensional ergonomic intervention model to reduce musculoskeletal discomfort among street sweepers in Chiang Rai Province, Thailand

Figures & data

Table

Levels	Severity of MSD levels
0	No MSD
1–3	Slight MSD
4–6	Moderate MSD
7–9	High MSD
10	Severe MSD

Table 1 Baseline characteristics compared between the intervention group and control group among street sweepers: categorical independent variables

Characteristics	Intervention (n=34)		Control (n=34)		P-value*
	n	%	n	%
Sex					0.377
Male	5	14.71	4	11.76
Female	29	85.29	30	88.24
Education					0.111
Primary school	27	79.41	31	91.18
Secondary school	7	20.59	3	8.82
Marital status					0.752
Married	31	91.18	33	97.06
Widowed/divorced/separated	3	8.82	1	2.94
Smoking					0.595
No	30	88.23	32	94.12
Yes	4	11.77	2	5.88
Drinking					0.650
Never	32	94.12	31	91.18
Sometimes	2	5.88	3	8.82
Take a break					0.169
No	27	79.41	28	82.35
Yes	7	20.59	6	17.65
Exercise					0.595
Never	30	88.24	32	94.12
Work out 1–2 times/week	4	11.76	2	5.88

Note:

* Significant at P<0.05, χ² test.

Table 2 Baseline characteristics compared between the intervention group and control group among street sweepers: continuous independent variables

Characteristics	Intervention (n =34)		Control (n =34)		P-value*
	Mean	±SD	Mean	±SD
Age (years)	47.59	7.25	47.71	8.01	0.337
Range (max =60, min =27)	28–59		26–60
Working years	14.74	7.57	15.03	8.94	0.824
Range	1–37		1–38
Body mass index (kg/m^2)	25.10	4.38	24.83	3.96	0.237
Range	17.50–34.90		18.60–39.80
Walking distance(km)	2.15	0.61	2.12	0.69	0.209
Range	1–3		1–3
Using broom per month	2.00	0.74	2.00	0.67	0.150
Range	1–3		1–3
Length of broom(cm)	162.88	13.01	161.46	9.32	0.662
Range	140–200		145–182
Weight of broom(g)	798.53	152.99	838.24	34.87	0.393
Range	550–1,000		600–1,000
Weight of broom and dustpan	1,725	205.33	1,750	192.27	0.562
Range (g)	1,300–2,000		1,350–2,000
Proportion (chin height and broom)	123.56	11.80	121.85	10.17	0.262
Range (cm)	101.96–153.85		106.67–146.34
Proportion (tall and broom)	106.98	10.08	105.83	8.44	0.281
Range	90.70–134.23		93.54–126.76

Note:

* Significant at P<0.05, t-test.

Abbreviations: SD, standard deviation; min, minimum; max, maximum.

Figure 1 Comparing the prevalence of musculoskeletal discomfort in the past 7 days between the intervention (n=34) and control groups (n=34).

Table 3 Comparing musculoskeletal discomfort score by physiotherapist between the intervention (n=34) and control groups (n=34)

Time of data collection	Musculoskeletal discomfort (score)		Mean difference	95% CI
	Intervention (mean ± SD)	Control (mean ± SD)
Baseline	7.21±0.98	7.21±0.87	−0.06	0.49 to0.43
Exit model (12 weeks)	5.62±0.85	7.53±0.73	−1.92	−2.33 to −1.55*
First follow-up (16 weeks)	4.38±0.78	7.15±0.77	−2.75	−3.13 to −2.40*
Second follow-up (20 weeks)	3.44±0.79	7.03±0.80	−3.59	−3.97 to −3.21*
Third follow-up (24 weeks)	3.26±0.79	7.24±0.70	−3.97	−4.36 to −3.61*
Fourth follow-up (28 weeks)	3.44±0.71	7.06±0.78	−3.62	−4.00 to −3.30*

Note:

* Significant at P<0.05, using independent t-test.

Abbreviations: CI, confidence interval; SD, standard deviation.

Table 4 Comparing upper body strength score by sports scientist between the intervention (n=34) and control groups (n=34) at the baseline, exit model, first, second, third, and fourth follow-up

Time of data collection	Musculoskeletal strength (score)		Mean difference	95% CI
	Intervention (mean ± SD)	Control (mean ± SD)
Baseline	9.65±1.04	9.62±1.30	0.02	−0.54 to −0.60
Exit model (12 weeks)	11.94±1.18	10.29±1.00	1.65	1.12 to 2.18*
First follow-up (16 weeks)	12.56±1.02	10.03±1.09	2.53	2.02 to 3.04*
Second follow-up (20 weeks)	13.00±0.92	9.94±0.98	3.06	2.60 to 3.52*
Third follow-up (24 weeks)	13.21±0.91	10.12±0.81	3.09	2.67 to 3.51*
Fourth follow-up (28 weeks)	12.94±0.78	9.91 ± 1.08	3.03	2.57 to 3.49*

Note:

* Significant at P<0.05, using independent t-test.

Abbreviations: CI, confidence interval; SD, standard deviation.

Table 5 Comparing lower body strength score by sports scientist between the intervention (n=34) and control group (n=34) at the baseline, exit model, first, second, third, and fourth follow-up

Time of data collection	Musculoskeletal strength (score)		Mean difference	95% CI
	Intervention (mean ± SD)	Control (mean ± SD)
Baseline	10.24±1.46	10.21±1.37	0.02	−0.66 to −0.72
Exit model (12 weeks)	11.79±1.43	10.50±0.93	1.29	0.71 to 1.88*
First follow-up (16 weeks)	12.94±0.95	10.24±0.86	2.71	2.27 to 3.14*
Second follow-up (20 weeks)	13.38±0.78	9.85±0.78	3.53	3.15 to 3.91*
Third follow-up (24 weeks)	13.76±0.74	10.03±0.72	3.73	3.38 to 4.09*
Fourth follow-up (28 weeks)	13.18±0.83	9.94±0.81	3.23	2.84 to 3.62*

Note:

* Significant at P<0.05, using independent t-test.

Abbreviations: CI, confidence interval; SD, standard deviation.

Table 6 Effectiveness of the MEI model for the mean MSD score between the intervention and control groups of street sweepers (n=68)

Source	SS	df	MS	F	P-value
Between subjects
Intervention	717.35	1	717.35	474.73	<0.0001**
Error	99.73	66	1.51
Within subjects*
Time	239.45	2.47	96.82	101.96	<0.0001**
Intervention* time	186.04	2.47	75.22	79.22	<0.0001**
Error	155.01	163.23	0.95

Notes:

* Greenhouse-Geisser;

** significant at P<0.01.

Abbreviations: df, degrees of freedom; MEI, multidimensional ergonomic intervention; MSD, musculoskeletal discomfort; SS, sum of squares; MS, mean squares.