The effects of using an ergonomic aid on the physical workload and body discomfort reported by pre-adolescent farmers in West Bengal,India

Abstract

BACKGROUND:

Musculoskeletal disorders are one of the major health hazards among farmers. Pre-adolescents are mainly associated with agricultural work due to poor socioeconomic conditions.

OBJECTIVES:

This study aims to implement a new ergonomics aid for the betterment of job procedures and improvement of productivity, health, and safety of the preadolescent farmers.

METHODS:

100 male and 100 female preadolescent farmers were randomly selected from the villages of Tarakeswar, West Bengal, India, to evaluate and reduce work-related musculoskeletal disorders, physiological stress. Modified Nordic questionnaires, Body Part Discomfort (BPD) scale, and handgrip strength were assessed before and after using the ergonomics aid.

RESULTS:

The results of the study show that there was a significant change (decrease) in discomfort in the lower back, wrists, shoulder, and hands among preadolescent farmers when using the newly designed ergonomic aid. Handgrip strength increased and physiological stress was decreased among preadolescent farmers in post-intervention than pre-intervention in just after work conditions. Productivity has been increased in farming by decreasing absenteeism from work with the use of ergonomic aid.

CONCLUSION:

This study concludes that productivity has been increased in farming by decreasing absenteeism from work as well as by using the ergonomic aid the discomfort feeling has been decreased markedly.

Keywords

Ergonomic aid preadolescent farmers Nordic questionnaire BPD scale handgrip strength

1 Introduction

Agriculture is one of the few industries in which children and adolescents are considered as an integral component of the workforce. The agricultural workers, especially children, often have musculoskeletal disorders, usually low back pain [1]. Musculoskeletal disorders are one of the most common problems among farmers [2]. Gangopadhyay et al. [3] also stated that the preadolescent agricultural workers are continuously exposed to constant bending posture in a different environment, as a result, they suffer from acute pain and discomfort for an extended period, which hampers and restrict their education and arouses the possibility of severe pain and musculoskeletal disorder in near future.

Children comprise a significant portion of the agricultural workforce and are exposed to many workplace hazards, including farm machinery, pesticides, poor field sanitation, unsafe transportation, and fatigue from doing physically demanding work for long periods [4]. Poverty is one of the leading causes of child labor in agriculture, together with limited access to quality education, low agricultural technology and access to adult labor, high hazards and risks, and traditional attitudes towards children’s participation in agricultural activities.

It is well known that agriculture is a very physically demanding occupation where muscular aches and pains are often considered to be part of the job. Preadolescent agricultural farmers suffered pain in different parts of the body exceptionally low back, shoulder, wrist, and knee [5]. It is also well known that agricultural works are associated with high rates of occupational injury, disability, and illness [6]. The occupational agricultural injury is also one of the main problems among the farmers, which may lead to physical disability among them due to working with not ergonomically designed hand tools [7]. Ergonomics interventions can provide educational, engineering, and environmental solutions to help reduce the potentials for strains and sprains that decrease a worker’s productivity level and may lead to more severe injuries.

Ridging is one of the main activities in potato cultivation, in which farmers mainly performed with the iron-made ridger which contains two or three columns with iron band wheels (ridger) which mostly rotate freely on the soil to protrude the soil before the potato seed is planted. Ridging activity was done mainly due to the easy passage of water through the ridge or groove of the land and the soil during potato cultivation. Certain crops – potato, cassava, maize for example – are grown on the ridges of soil in some farming systems. The top of the ridge is only wide enough to accommodate one row of plants. In the irrigated farming system, water is fed into the ditches between the ridges [8]. Ridges are also formed for water and soil conservation [9]. Ridging activity in potato cultivation was generally done by pulling the device with both hands without back support, which may lead to severe discomfort feeling (pain) in the subjects.

Generally, children and adolescents are mainly involved in agricultural works to help their families in their land as well as work as cheap child labor to support their families by earning money. In West Bengal, especially in Hooghly District (Tarakeswar) potato farming is a major where millions of adult farmers along their children and adolescent works for more potato and vegetable cultivation. Ridging activity in potato and vegetable cultivation was generally done by pulling the device with both hands without back support, which may lead to severe discomfort feeling (pain) to the subjects. Children and adolescents are feeling severe pain while pulling the massive iron ridge for potato and vegetable cultivation.

The main aim of the present investigation is i) to determine the prevalence of musculoskeletal disorders among preadolescent potato farmers, ii) to determine the effect and compare the result of newly designed ergonomics aid for the betterment of job procedure for the improvement of productivity, health, and safety and prevention of the preadolescent farmers with previous procedure, iii) to measure the handgrip strength before and after use of ergonomics aid among both groups of preadolescent potato cultivators, iv) to measure the physiological stress before and after the use of ergonomics aid among both groups of preadolescent potato cultivators.

2 Materials and methods

2.1 Selection of subjects

Preadolescent farmers are suffering from musculoskeletal pain by doing ridging activity in potato cultivation by helping their families or earning as child labor. This study tries to resolve the problem by pushing the ridgers instead of pulling. This study mainly selects preadolescents to resolve their problems and giving them a better future.

The study was performed on 200 preadolescent potato cultivators (farmers), who were randomly selected from the villages of Tarakeswar of West Bengal comprising 100 males and 100 females. This observation study has been conducted for 12 months study period. Before the study, consent was taken from preadolescent farmers and the parents or local guardians of the preadolescent. Necessary Ethical clearance was granted by the Institutional Ethical Clearance Committee of the Indian Council of Medical Research Guidelines Committee.

2.2 Measurement of physical parameters

The stature and weight of the preadolescent farmers were measured by Martin’s Anthropometer and weighing machine (Crown, Mfg. by Raymon Surgical Co.) respectively. The Body Mass Index (BMI) of all the preadolescent potato cultivators was also computed by using the following formula: $BMI ({kg / m}^{2}) = Weight (kg) / height (m^{2})$

2.3 Questionnaire study

A detailed study based on a modified Nordic questionnaire [10] was performed among these preadolescent farmers. The surveys were conducted mainly to assess the discomfort feeling before and after using the newly designed ergonomics aid in ridging activity along with health problems among them. The questionnaire comprised a series of objective questions with multiple-choice responses. The modified Nordic questionnaire has been translated in Bengali (local language), the translated questionnaire was applied by adult farmers and the translated questionnaire was rectified according to the suggestion of adult farmers, and then it was used to the child and adolescent potato farmers. The questions were grouped into some significant sections, dealing with: individual details, type of work, upper extremities musculoskeletal symptoms, other affected body parts, etc. For the symptom survey, the subjects were enquired whether they suffered from tenderness, swelling, and warmth in the wrist and pain numbness and tingling in the hands.

2.4 Discomfort level scale

The intensity of pain/discomfort feeling was measured by utilizing the body part discomfort (BPD) scale [11]. The rating of each body part on a scale from 1 to 10 was done to indicate the level of discomfort. In this 1-to-10-point scale for discomfort and pain sensation, 1 represented just noticeable pain, point 5 scales represented moderate pain or discomfort, and pointed 10 scales expressed intolerable pain or discomfort.

2.5 Measurement of hand grip strength

A handgrip dynamometer is a hand-held device for measuring the maximum static force exerted by the hand. The preadolescent farmers perform pulling activities during ridging by which the strength of the hand muscle alters among the workers. This alteration was measured by a handgrip dynamometer. Similar findings have been found by Levk et al. [12]. According to them, handgrip strength has been identified as one limiting factor for manual lifting and carrying loads. A physical examination was performed by handgrip dynamometer (Make: Rolex, India) to measure the handgrip strength of the preadolescent farmers. The preadolescent farmers were asked to grip the dynamometer with full force in a straight and standing position without side bending and keeping arms at their side and not touching the body [13, 14]. The measurement of the dynamometer was generally done twice in a day, before ridging activity in potato cultivation and just after completion of ridging activity in potato cultivation among the preadolescent farmers at 90° elbow flexion and 180° elbow flexion [15].

2.6 Assessment of physiological stress

Physiological stress assessment was carried out by recording the heart rate and blood pressure of the preadolescent farmers with a sphygmomanometer (Make: Diamond) and stethoscope (Make: Diamond) before work and just after completion of work before and after using the ergonomics aid. The resting or before work heart rate was measured from the radial pulse for one minute with the help of a stopwatch, and the heart rate just after work was recorded from the carotid pulse by 10 beats method [16]. The blood pressure of the male and the female preadolescent subjects was measured with a sphygmomanometer and stethoscope before and just after the completion of work. Energy expenditure of the subjects was determined by applying the formula: $[0.159 \times heart rate (beats / main) - 8.72]$

2.7 Design of ergonomics aid

The adjustable ergonomics aid was designed with nylon clothes, straps, plastic fiber & sponges to decrease the discomfort feeling of the user. The sponge was placed in between the nylon clothes and synthetic fiber for the betterment of back support. Two adjustable straps were made up of nylon clothes and sponges and were fixed at the shoulders before use. Another two adjustable straps which were come out from the middle part of the back support and were attached with the handle of two spiked plowing tools to provide support to the rear region of the body during pushing in ridging activity, while using newly designed ergonomic aid. The shape of the ergonomics aid was almost rectangular and was placed lengthwise. The ergonomics aid was fabricated according to the anthropometric data measurement among the preadolescent farmers in the following dimensions: Length—18 inches, Width—14 inches, Thickness—2 inches. The weight of this aid was 0.8 kg. The cost of the ergonomics aid is rupees 290.00 or the US $4 (approx.) (Kolkata, India). A comparative study was made among the male and the female preadolescent potato farmers before and after using the ergonomics aid in the same place for the 12 months study period.

2.8 Data analysis

Student’s t-test was performed to find out the significant difference of demographics characteristics between the male and female preadolescent farmers. A two-tail chi-square test of independence was applied to determine whether there is any significant association between the parameters measured before and after using the ergonomic aid. The computed χ² was next compared with the critical χ² value for the chosen level of significance (p < 0.05). Student’s t-test was used to find out the significant difference of discomfort feeling (pain) according to body parts discomfort (BPD) scale measured, before and after using the ergonomic aid by the preadolescent farmers. One-way ANOVA was also performed to compute the F ratio to find out whether there is any significant difference between the handgrip strength, heart rates, blood pressure, energy expenditure, net cardiac cost, and relative cardiac cost in resting condition, just after stoppage of work without using ergonomics aid and just after stoppage of work for the chosen level of significance (p < 0.05). The student t-test was also performed to assess the lung function values and respiratory symptoms between potato preadolescent farmers (with ridger) and other preadolescent farmers (without ridger). Statistical analysis was performed using the statistical package PRIMER OF BIOSTATISTICS (Primer of Biostatistics 5.0.msi, Msi Version = 1.20.1827.0, Primer for Windows, Mc-Graw-Hill).

3 Results

The mean values of age, physical parameters (height, weight, BMI), and the average years of experience of the subjects in the male and female preadolescent potato farmers are shown in Table 1. The average duration of work of the male preadolescent potato farmers is 3.9 (SD±0.84) hrs per day. The average length of action of the female subjects is 3.8 (SD±0.74) hrs per day.

Table 1
Physical characteristics of the preadolescent potato farmers

Parameters Male Female t value p value

Age (years) 11.94 (±1.41) 12.00 (±1.39) 0.303 0.762

Height (cm) 156.4 (±3.98) 155.1 (±3.99) 2.307 0.022

Weight (kg) 35.64 (±4.05) 36.93 (±5.58) 1.871 0.063

BMI (kg/m²) 14.53 (±1.04) 15.30 (±1.91) 3.541 0.000

Years of work experience 2.72 (±1.10) 2.83 (±1.12) 0.701 0.484

Duration of work per day (hour) 3.98 (±0.84) 3.79 (±0.74) 1.697 0.091

Parameters	Male	Female	t value	p value
Age (years)	11.94 (±1.41)	12.00 (±1.39)	0.303	0.762
Height (cm)	156.4 (±3.98)	155.1 (±3.99)	2.307	0.022
Weight (kg)	35.64 (±4.05)	36.93 (±5.58)	1.871	0.063
BMI (kg/m²)	14.53 (±1.04)	15.30 (±1.91)	3.541	0.000
Years of work experience	2.72 (±1.10)	2.83 (±1.12)	0.701	0.484
Duration of work per day (hour)	3.98 (±0.84)	3.79 (±0.74)	1.697	0.091

Table 2 represents the discomfort feeling at different body parts of the male and female preadolescent potato farmer’s pre-and post-intervention. Among all areas of the preadolescent farmer’s body, the lower back and wrist are the most affected regions among both groups (male and female) of preadolescent potato farmers due to pulling the heavy iron made ridger. Table 2 shows that 95%of male and 98 %of female preadolescent potato farmers suffered pain in the lower back before using ergonomics aid in ridging activity. Whereas this becomes reduces to 78 %and 72 %respectively after using the ergonomics aid. The same observation has been found in the case of wrist which reduces to 68%to 31%in case of male preadolescent farmers and 75%to 22%in the case of female preadolescent farmers respectively. Shoulder and hand were the next two regions that affected body parts due to pulling the heavy iron ridger. The discomfort feeling (pain) has been significantly reduced from 66 %to 42 %in the shoulder region in case of male 72 %to 49 %in the case of female preadolescent potato farmers after using the ergonomics aid. In the case of the hands of male and female preadolescent farmers, the pain has been reduced from 62%to 37%and 67%to 39%respectively. This observation has been found during the 12 months study period.

Table 2

Discomfort feeling at different body parts of the male and female preadolescent potato farmers before and after using of ergonomic aid

Body parts	Male preadolescent potato farmers (n = 100)					Female preadolescent potato farmers (n = 100)
	Before using ergonomic aid	After using ergonomic aid	OR	95%CI	p value	Before using ergonomic aid	After using ergonomic aid	OR	95%CI	p value
Neck	60	52	1.38	0.79–2.42	0.994	68	57	1.60	0.90–2.85	0.144
Shoulder	66	42	1.60	0.90–2.85	0.001^***	72	49	2.67	1.48–4.81	0.001^***
Elbows	53	42	1.55	0.89–2.72	0.157	55	43	1.62	0.92–2.83	0.120
Wrists	68	31	4.72	2.60–8.59	0.000^***	75	22	10.6	5.52–20.5	0.000^***
Hands	62	37	2.77	1.56–4.92	0.000^***	67	39	3.17	1.77–5.66	0.000^***
Upper back	25	20	1.33	0.68–2.59	0.498	22	18	1.28	0.64–2.57	0.596
Lower back	95	78	5.35	1.93–14.8	0.000^***	98	72	19.0	4.39–82.6	0.000^***
Knees	52	41	1.55	0.89–2.72	0.156	63	49	1.77	1.00–3.11	0.064

^*** = Significantly change.

Table 3 presents the average BPD scale rating of the male and female preadolescent potato farmers. These results (Table 3) show that the discomfort feeling (pain) is significantly less after using ergonomics aid in comparison to before using ergonomics aid. Table 3, indicates that there is a significant decrease (p < 0.05) of the BPD scale rating (6.5 to 4.4). Whereas, the same type of BPD scale rating results 6.9 to 4.6 has been found.

Table 3

Comparative discomfort feeling (pain) according to body parts discomfort (BPD) scale

A significant change in handgrip strength at 90° and 180° elbow flexion was found in between resting conditions, during work with and without intervention among the male and the female preadolescent farmers (Table 4). This result also shows that the handgrip strength of the male and the female potato farmers has been significantly changed (p < 0.05) at 90° elbow flexion and 180° elbow flexion after using the ergonomics aid, compared to without the use of the ergonomics aid in ridging activity in potato cultivation.

Table 4

Handgrip strength (in kg) of the male and female preadolescent agricultural workers with and without intervention

Subjects	Hand grip strength	MVC normalized values during resting condition Mean SD	Hand grip force values during work without intervention Mean SD	Hand grip force work with intervention Mean SD	F value	p value
Male potato farmers	90° elbow flexion	22.4±9.72	19.2±8.51	21.6±9.45	3.25	0.040
	180° elbow flexion	22.4±9.72	18.1±8.85	20.1±9.01	3.92	0.021
Female potato farmers	90° elbow flexion	21.7±9.45	18.4±8.46	20.9±9.32	4.84	0.009
	180° elbow flexion	21.7±9.45	17.8±8.73	19.9±9.06	4.62	0.011

The physiological stress of the male and the female preadolescent potato farmers was shown in Table 5. From this result, it was observed that the average just after stoppage of work heart rate of the male and the female preadolescent potato farmers has a significant change (p < 0.001) in case of after using the ergonomics aid than the before using ergonomics aid in ridging activity in ridging activity in potato farming. But there is no significant change in just after of work blood pressure (systolic and diastolic) before and after using ergonomic aid among female preadolescent potato farmers. The energy expenditure of the male and the female preadolescent farmers has got a significant effect by using ergonomics aid. However, significant changes were also observed in net cardiac cost and recovery cost after using the ergonomics aid than the previous condition among both the group (male and female) of potato farmers (p < 0.001).

Table 5

Physiological stress among male and female preadolescent potato farmers before and after using Ergonomic Aid

Physiological parameters	Male preadolescent potato farmers				Female preadolescent potato farmers
	Before using ergonomic aid	After using ergonomic aid	F value	p value	Before using ergonomic aid	After using ergonomic aid	F value	p value
Average heart rate (beats/min) just after stopping work	105.4±6.3	102.5±4.47	14.09	0.000^***	107.2±5.8	104.1±6.53	13.56	0.000^***
Average blood (mm/Hg) Systolic pressure	116.6±6.47	114.8±6.83	3.66	0.057^***	107.6±6.9	106.9±6.36	0.55	0.458
Average blood (mm/Hg) Diastolic pressure	72.8±4.73	72.0±4.64	1.46	0.229	72.2±4.56	71.8±4.13	0.42	0.516
Energy expenditure	8.03±1.00	7.6±0.71	12.3	0.000^***	8.3±1.17	7.8±1.03	10.29	0.002^***
Net cardiac cost (NCC)	22.7±7.32	14.3±4.9	90.94	0.000^***	19.7±5.11	14.95±4.63	47.45	0.000^***
Relative cardiac cost (RCC)	27.4±5.53	16.2±3.61	287.62	0.000^***	22.5±4.08	16.8±3.62	109.21	0.000^***

^*** = Significantly change.

Table 6 presents that there was a significant change in absenteeism from work (ridging activity in potato farming) before using ergonomics aid and after using ergonomics aid among male and female preadolescent farmers. Table 6 shows that 36%male was absent from work due to discomfort feeling (pain) before using ergonomics aid in the previous seasons, this number has been reduced to 10%by using the new ergonomic support in next season. The same type of results has been found in the case of female preadolescent farmers also. The number of absenteeism has been reduced from 52%to 14%after using the new design ergonomics aid. The productivity of the agricultural activities has been noted by the preadolescent farmer’s presence in workers in the agricultural field. The result of the study found that before using the ergonomic aid the preadolescent farmers felt more pain in different parts of the body which they cannot join in their work regularly. On the other hand, after using the new ergonomic aid it was observed that the absenteeism from work by the preadolescent farmers has been decreased. This indicates the productivity of work has been increased.

Table 6

Average number of workers absenteeism of work before and after using the ergonomic aid among the male and female preadolescent potato farmers

Preadolescent agricultural workers	Average number of workers’ absenteeism from work before using ergonomic aid	Average number of workers’ absenteeism from work before using ergonomic aid	OR	95%CI	P value
Male	36	10	5.06	2.34–10.93	0.000
Female	52	14	6.65	3.34–13.23	0.000

Figure 1 shows the newly designed ergonomics aid (front and side view). Figure 2 shows the ridging activity with an existing hand tool and the ridging activity with a newly fabricated ergonomics aid. Ridging activity in potato and vegetable cultivation was done with heavy iron made ridger, which have to pull by the farmers to make a ridge in the agricultural land for passing the water for better germination. But iron made ridger is too heavy for the preadolescent farmers to pull, which mainly created discomfort in different parts of the body among the preadolescent farmers. Newly ergonomic aid mainly helps to push the ridger instead of pulling. Ergonomic aid was made with adjustable back support along with two strips which were attached with the handle of iron made ridger.

Fig. 1

Newly fabricated ergonomics aid: front view (left) and side view (right).

Fig. 2

Ridging done with existing hand tool and done with newly fabricated ergonomics aid.

Figure 3 indicates the type of discomfort is feeling before and after using the ergonomics assistance among preadolescent potato farmers, where the pain is the predominant one. This figure also indicates that there is a marked decrease in discomfort after using ergonomic aid. Figure 4 also shows the comparative study of feelings of discomfort (pain) at different times among the preadolescent potato farmers before and after using ergonomic aid.

Fig. 3

Type of discomfort feeling before and after using the ergonomic aid among preadolescent potato farmers.

Fig. 4

Comparative study of feelings of discomfort (pain) at different times among the preadolescent potato farmers before and after using ergonomic aid.

4 Discussion

Agriculture is the primary source of livelihood for the majority of the population in India. Agriculture has been established as one of the drudgery-prone occupations of the unorganized sector due to lack of access to improved agricultural technologies [17]. This study mainly focused to compare the result of newly designed ergonomics aid for the betterment of job procedure for the improvement of productivity, health and safety, and prevention from work-related musculoskeletal disorders among preadolescent farmers with the previous method in ridging activity in potato cultivation. By applying the newly designed ergonomic aid it has been found that the work-related musculoskeletal disorders have been reduced by which the preadolescent farmers can also get rid of pain and discomfort feeling by doing the ridging activity in farming. Workers in the agricultural industry have exposure to many of the recognized risk factors for work-related musculoskeletal disorders [18, 19]. While modern mechanized agriculture has eliminated much of the manual work in many sectors, vegetable production throughout the world still involves hazardous repetitive manual Labor [20, 21]. Hand tool mechanisms designed to reduce the risk factors have rarely been studied [22]. Thus, the implementation of new ergonomic aid for the children helps to reduce the discomfort feeling, which improve their health and also improve their education. Improve work organization or the development of tools may lead to improve productivity in different unorganized sectors [23]. Today, in this current situation, researchers try to found the low-cost ergonomic interventions to reduce postural stress and work-related musculoskeletal disorders in the different farming sectors among the farmers. Recently, Mokarami et al. [24] also found a similar type of results, and they stated that applying participatory ergonomic principles along with low cost and simple designs with high performance resulted in significant reductions in postural risks about musculoskeletal disorders.

Agricultural tasks in developing countries in the tropical region are expected to cause musculoskeletal disorders. Improved tools or task-design based solely on the researcher’s perceptions of a need for improvements is unlikely to achieve a significant impact. The application of ergonomics has the potential to reduce biomechanical disorders associated with agricultural tasks or tools [25]. The majority of the farmers of India cannot afford heavy or sophisticated machinery; this leads to the improvisation of the existing method of work to minimize the overall physical demands of their task within allowable limits and to increase the aggregate output of the workers [26]. Das and Gangopadhyay [27] stated that due to improper design hand tools the severe musculoskeletal pain has been found in the case of adult male potato cultivators. Several research studies have investigated the prevalence and risk factors for musculoskeletal symptoms in general agricultural workers [28, 29]. Gangopadhyay et al. [3, 5], has been found the preadolescent farmers had some discomfort feeling at different parts of their body due to working in an awkward posture for a prolonged period and without properly design hand tools, which are highly undesirable according to ergonomics criteria. But the researchers in their previous study did not implement or suggest any tools by which the children or preadolescent get rid of pain during or after work. But this study tries to evaluate the work-related musculoskeletal disorders and try to solve the problems by implementing ergonomic aid. This study also shows that absenteeism from agricultural work among preadolescent farmers has been reduced by implementing new ergonomic aid, by which the productivity has been increased. This result has been supported by Tadesse et al. [30]. They also suggest that absenteeism, sickness affects the productivity of agriculture. They also implement their intervention to reduce absenteeism, illness to increase productivity in horticulture. So, reduce absenteeism from work leads to improve productivity. The similar types of findings have also been established by other researchers. Gangopadhyay et al. [31], Das [23, 32] found the similar findings in the case of sand core and brickfield workers respectively.

Pushing and pulling are the most common human activities in several occupations involving manual material handling. Nearly half of all manual material handling activities consist of pushing and pulling forces [33 –35]. Most of the agricultural activities such as the operation of manual ridgers, push/pull weeders, etc. involve pushing and pulling in standing and walking posture [36]. In this study, it was revealed that the preadolescent potato farmers are engaged in a different awkward position (pulling activities) in the operation of manual ridgers, which may lead to discomfort feeling (pain) among them. This can be attributed to their remaining in a constant awkward posture and repetitiveness of the work may lead to MSD. They also reported that repetitiveness of the work might lead to the development of the musculoskeletal problem. Das [37 –40] further stated that awkward posture during work might lead to the development of the musculoskeletal disorder. Usage of the ergonomics aid during ridging activity in potato cultivation decreases the discomfort feeling in different parts of the body especially lower back, wrist, hand, shoulder, and knee among both the group of the workers due to pushing with newly designed ergonomics aid than pulling by hand the heavy ridger made of iron. This result corroborated the studies of Lee et al. [41], who stated that pushing a cart results in lesser lower-back loading than pulling. Chafin [42] and Grieve [43] also said that hauling task in agricultural work is accompanied by an increased risk of farm accidents due to slipping or tripping, which can cause injuries to the musculoskeletal system. So, the newly designed ergonomics aid provides back support which reduced the low back pain as well as wrist and hand pain among both the group of the preadolescent potato farmers.

A significant difference in handgrip strength just after completion of work condition before using and after using the ergonomics aid in ridging activity was observed among the male and the female preadolescent potato farmers. This result corroborates with the work of Das et al. [13]. According to them, the workers are engaged continuously in the hand-intensive job (by pulling) which may lead to discomfort in the upper parts of the body, and that leads to a significant change in handgrip strength in contrast to the subjects using the ergonomics aid not engaged in the hand-intensive job. Domizio and Keir [44] also stated that pulling activity by hand decreases the grip and muscle activity of the workers which may lead to fatigue among them.

Just after completion of work heart rate before using the ergonomics aid of the male and the female preadolescent potato farmers are significantly high which may be due to constant movement of the body, moreover when a male or a female preadolescent potato farmer bend backward for dragging the iron ridger to protrude the soil for potato cultivation, the muscles of the abdomen contract and muscles of the back are stretched. This contracting and stretching of the muscles require energy. Therefore, the heart was to beat faster to supply more blood to the muscle [45]. But after the uses of the ergonomics aid the heart rate and the blood pressures (systolic and diastolic) were much less due to less strenuous activity and the use of energy was significantly less in comparison to without using the ergonomics aid.

5 Intervention measured

This study mainly found that after using the ergonomic aid by the preadolescent farmers, the farmers felt less pain in their body along with other types of less discomfort like pain, tingling, stiffness, and numbness in their hands. This study also found that the discomfort feeling (pain) according to body parts discomfort (BPD) scale are significantly change (less) after using the ergonomic aid. Prior to this study, the preadolescent farmers are pulling the iron made ridger, but, after using the ergonomic aid, the preadolescent farmers do not pull the ridger. Instead of pulling they push the ridger by which the hand grip strength of preadolescent farmers has been increased due to not involving their hand to pull the ridger. Some of the important physiological parameters shows significantly change after using the new ergonomic aid. The current study found that physiological parameters like- just after stoppage of work heart rate, systolic blood pressure, net cardiac cost, relative cardiac cost and above all energy expenditure has been significantly changed after using the newly designed ergonomic aid in the case of both male and female preadolescent farmers. This may be due to, they have to performing the agricultural work without any strenuous work. Generally, it was well known that agricultural tasks are hard-working tasks for all types of farmers, especially preadolescent farmers. Before using ergonomic aid, the farmers generally absent from work frequently due to feeling pain in their different parts of the body, especially wrists and hands. But after using the newly designed ergonomics aid the absenteeism from the work has been reduce significantly among both group of farmers, which shows that, they enjoy the work and attain the work regularly, to increase the productivity in the farm.

6 Limitations

This study had several limitations. Firstly, this study involved data collection from the preadolescent farmers (age group- 10–14 years), not for adolescent and adult farmers. Besides that, in this current study, the preadolescent farmers have to be involved with pulling activities. In this study, there is a lack of EMG studies by which it can observe the details of muscle activity along with the impact of the muscle fatigue analysis of the preadolescent farmers. This study had some other limitation like, the measurement of physiological parameters which was measured manually. Future research should be carried out among the preadolescent farmers with larger sample sizes to initiate the development of successful intervention strategies.

7 Conclusion

From this study it can be concluded that the preadolescent potato farmers work continuously pulling activity with heavyweight, iron made ridger, which may lead to different types of discomfort feeling (pain, numbness, swelling, stiffness) in the wrist, hand, shoulder, and lower back region of the body, which may lead to affect their health and restrict their education. By using the ergonomic aid, the preadolescent potato farmers reduce the pain in the upper extremity and lower back in the body, which helps their health, by applying pushing activities instead of pulling activities. The result of the study showed that, the discomfort feeling (pain) according to body parts discomfort (BPD) scale was significantly less after using the newly designed ergonomic aid, in compare to before using ergonomic aid among both groups of preadolescent farmers. Again, by using the ergonomic aid the handgrip strength and physiological stress of the preadolescent farmers has been improved, which ultimately improves their health. Thus, the application of the ergonomics aid in ridging activity in potato cultivation has markedly and significantly increased the productivity of the workers by decreasing the absenteeism from work of the preadolescent farmers during ridging activity in potato cultivation.

Footnotes

Acknowledgments

The authors express their sincere gratitude to all preadolescent agricultural workers and their parents and guardians for their co-operation during this study.

Conflict of interest

No conflict of interest was reported by the authors.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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