Abstract
BACKGROUND:
In the adult population, the work environment and physical fitness levels are directly related to the onset of musculoskeletal pain, repetitive strain injuries, and decreased blood circulation. Although low levels of muscle strength and flexibility may lead to a higher prevalence of pain, specific anatomic regions are poorly addressed.
OBJECTIVE:
To investigate the prevalence of musculoskeletal pain and the association between strength or flexibility and pain in university staff.
METHODS:
The sample was composed of 110 members of staff from a university in Guarapuava-PR. Body mass and height values were obtained, from which the BMI was calculated. The pain evaluation was performed by means of a questionnaire, analyzing the intensity, frequency, and anatomical region. The subjects were then submitted to strength (right and left hand grip, lumbar traction, lower limb traction) and flexibility tests (sit and reach test).
RESULTS:
The anatomical region with the highest prevalence of pain was the lumbar region (43.4%). When the association between the presence of pain and flexibility was performed, only the lumbar traction presented significant results, with the weakest group demonstrating pain (OR: 3.47 [1.27 – 9.49]).
CONCLUSION:
The results demonstrate that low levels of strength in the lumbar region are associated with the presence of painful symptomatology.
Introduction
Although the health of the world population is a topic that has been discussed for decades, in the present day, chronic degenerative diseases have begun to gain more importance in this scenario, significantly increasing public health expenditures [1]. As this expenditure reaches up to 7.5 billion a year, it is presented as being not only a public health problem but also an economic issue [2].
The work environment and labor physical activity, one of the domains of daily activities [3], are associated with pathologies that interfere with the health and quality of life of the population. Different types of work activities are associated with sedentary hours of work, incorrect work ergonomics, excessive working hours, and a reduction in daily energy expenditure, leading to an increase in the incidence of chronic noncommunicable diseases [4–6].
Work is of paramount importance to an individual, through performing tasks the employees feel productive and valued, this being beneficial to both social and mental aspects. However, long working hours and high sedentary time can become detrimental to worker health [7]. Among these factors, decreased blood circulation, musculoskeletal pain, and repetitive strain injuries are present in the health of employees [8], leading to reduced work output, excessive absences, and functional disability.
The control of musculoskeletal disorders needs to be included in the healthcare of university employees, as the prevalence of musculoskeletal disorders in university workers who performed office worker is 85%, the most affected regions are the neck (58%), shoulder (57%), and lumbar (51%). Musculoskeletal disorders in these regions have been associated with a higher time of office work and computer work [9].
In addition, employees affected by repetitive strain injury, on average, were absent from work for 336 days [10] and those affected by musculoskeletal disorders were absent for 130 days [11]. In Brazil, many universities are public, where all employees receive payment from the government; in this case, the healthcare of these employees is extremely important to help control expenses from health insurance. In addition, the absence of work can lead to a decrease in productivity, prejudicing the general community, since many university agents have functions in hospitals, administration of public services, research, and security.
According to the World Health Organization [12], in addition to the population achieving at least 150 minutes of moderate physical activity per week, muscle resistance exercises should be performed at least twice a week for better health and prevention of chronic noncommunicable diseases; being that, the higher the levels of physical activity and intensity, the better the results [12–14]. Additionally, university staff classified as insufficiently active can reach up to approximately 12 hours in sedentary behavior [15]. Elevated time in sedentary behavior can cause considerable loss of muscle mass and, consequently, higher fatigability, a result of so-called disuse syndrome, which results in apoptosis of Type 2 fibers [16]. In addition, this sedentary behavior can lead to impairments in the health of the worker, such as painful symptomatology in skeletal muscle. In several pathologies, the presence of muscular pain is associated with low physical fitness and muscular fatigability, which can remain for 90% of the day [17, 18].
When analyzing muscle pain in the lower back, physical fitness, particularly satisfactory rates of muscle resistance/strength, may have a great association as a protective factor for low back pain and the prevention of musculoskeletal pain [19, 20]. In addition, muscular fatigue has a direct relation with complaints of muscular pain, and also presents a mediation role between muscular complaints and workload, working posture, lack of energy, physical effort, sleepiness, or lack of motivation [21].
Another factor that may be associated with musculoskeletal pain and muscle injuries is flexibility, in many cases the decrease of flexibility is a protective response to the pain. Furthermore, tightened tissues can enhance the chances of developing muscular injuries [22–24]. A study of workers in the textile industry showed that increased flexibility, after an intervention program, significantly reduced worker withdrawal due to the incidence of low back pain, as well as 90% of cases of low back pain [23]; however, data on flexibility are inconsistent and scarce.
In view of the above, it is important to evaluate if strength or flexibility have an association with pain symptomatology, since lower levels of both variables can be predictors of muscular pain. Thus, the objective of the present study was to investigate the prevalence of musculoskeletal pain and its associated factors in university staff of the Universidade Estadual do Centro-Oeste (UNICENTRO).
Materials and methods
Research design and sample
This descriptive cross-sectional study was initially approved by the Human Research Ethics Committee of the Universidade Estadual do Centro-Oeste – UNICENTRO (opinion no. 857.658/2014). All staff from the university UNICENTRO were invited to participate in the research and signed the Free and Informed Consent Term. The sample size was calculated posteriori, from the total number of workers, 220 effective members of staff, considering a margin of error of 6.6%, with a confidence interval of 95%, and an effect size of 50%, resulting in 110 individuals. Data were collected from 110 members of staff at the university (60 men and 50 women).The members of staff who were not evaluated were excluded for the following reasons: 27 refused to participate, 9 were on leave, 3 were on vacation, 64 were not found at their job posts, 3 worked outside the municipality, 3 worked at night, and 1 no longer worked at UNICENTRO. The workers not found at their job posts, were visited on 3 attempts, on alternate days.
The inclusion criteria were that the employees must work exclusively and full time at the university; be a university agent. The exclusion criteria were present any injury or have undergone surgery recently; not signing the Free and Informed Consent Term; present limitations for the execution of the evaluated movements.
The Universidade Estadual do Centro Oeste is located in the southern region of Brazil, with 38 undergraduate courses, 16 master degree courses, and 5 doctoral degree courses. The university is located in Guarapuava-Paraná, which has a schooling rate of 97.1%, and an HDI of 0.731.
Data collection
The research was performed over the years 2014 and 2015, and the data were collected during the expedient of the work (8– 12 AM and 14– 17 PM). It took approximately 30 minutes for each subject to perform all the tests. Initially, the agents were approached at their workstations, subsequently, the research was described, and the Free and Informed Consent Term was delivered. The questionnaire was given to the participants, with a practical explanation about its operation. Participants completed the questionnaire individually, without the influence of or contact with other individuals, on which they were required to report the frequency and intensity of regions where they experienced some pain.
After completion of the questionnaire, the participants performed the manual grip test, lumbar traction, leg traction, and sit-and-reach test. All tests were conducted by a previously trained researcher with understanding of the protocols. For the strength tests, participants were instructed on the operation of the instrument and protocol procedures and two attempts were allowed to familiarize the individual with the instrument. For the data collection, three maximal attempts were performed, with a 2-minute interval between attempts, using the highest observed value. In the flexibility test, the sit-and-reach, the participants were allowed three attempts to obtain the greatest flexibility values and, for validation, the individual was required to maintain the value reached for two seconds.
Analysis of the frequency of musculoskeletal pain
Pain was analyzed through topography and pain intensity by means of a questionnaire proposed by Corlett and Bishop [25], which is composed of 11 different body regions, with an analysis of pain intensity and frequency. The intensity was analyzed by means of an Ordinal scale, on which 0 characterized “no pain” and 10 “maximum pain”. The pain frequency was separated into “occasionally”, “almost always”, and “always”.
Self-report measures
Data on body mass (kg) and stature (cm), were collected in a self-reported manner, and inserted in the musculoskeletal pain analysis questionnaire through a further response field. Despite the use of self- reported measures, this procedure has been previously validated and presented good validity and reproducibility [26–28].
Subsequently, the BMI (Kg/m2) was calculated for classification of nutritional status according to the WHO criteria [29].
Muscular strength and flexibility
For the analysis of muscular strength, four tests, already standardized [30], of manual right and left hand grip, lumbar traction, and lower limb strength were performed. The measuring instruments used were the manual grip dynamometer with a capacity of 100 KgF and a lumbar traction dynamometer with a capacity of 200 KgF (Crown®, Filizola, São Paulo, Brazil). All dynamometers were calibrated for this research. The flexibility analysis was performed by the sit-and-reach test, using the protocol described by Guedes [30].
Statistical analysis
The descriptive data were tested by the Kolmogorov-Smirnov test and compared by the T-Test for independent samples, presented as mean and standard deviation. The association between gender and pain was developed with the Chi-squared test. The regions of pain are expressed in frequencies according to the workers that reported a sensation of pain; the median was calculated to describe the intensity and frequency of pain. For the Odds Ratio analysis between strength and the presence of pain in any region, the groups were separated between the top 25% (F > 75%) compared to the remainder (F < 75%) for all independent variables (strength and flexibility). Only the results that presented values of P < 0.1 for the Chi-squared test were analyzed by binary logistic regression. Men and the women were analyzed individually between their respective quartiles and later grouped. Thus, binary logistic regression was performed with 95% confidence intervals. To control for potential confounders, sex and age were inserted as adjustment variables in the model. All data were analyzed in SPSS 25.0 software, and values were considered significant when p < 0.05.
Results
Table 1 presents the characterization of the sample separated by gender, which demonstrates significant differences for body mass and height between men and woman. The sample was composed of white collar workers (63.6%), Digital Skills (7.3%), Maintenance (6.4%), Secretariat (13.6%), and Caretakers (9.1%). The BMI presented mean values of overweight for men (26.7 Kg/m2) and normal weight for women (24.4 Kg/m2). The lumbar traction strength, for males, presented a mean of 148.07 (13.7) Kgf for the strongest quartile (>75%). The weaker quartiles, meanwhile, presented a mean of 99.13 (24.7) Kgf. These differences remained for the manual grip strength (49.8 vs 26.5 Kgf) and leg traction (119.1 vs 53.6 Kgf).
Descriptive analysis of data and comparison between the sexes
Descriptive analysis of data and comparison between the sexes
*Data are presented as Mean ± Standard deviation. For the presence or absence of pain values, the frequency values of the subjects are presented.
Table 2 presents the description of the regions and frequencies of pain. It can be observed that a total of 76 staff members (69.1%) reported some sensation of pain, with a mean intensity of 5.3 on a Likert scale with a maximum of 10 points. The greatest frequency of pain was reported in the back regions, this being more evident in the lumbar region (43.4%) and upper region (30.3%). The shoulders presented a mean frequency of 23.6% (n = 26), included as the third most affected anatomical region by the presence of musculoskeletal pain. Figure 1 presents the pain intensities in different anatomical regions; usually the median presented values of moderate pain, with some more symptomatic regions demonstrating values above moderate.
Number and frequency of musculoskeletal symptoms
The data are expressed in absolute values and their respective frequencies. *The same individual may present pain in more than one body region. #The values are described by the presented median.
Pain intensity.
When evaluating the presence of pain, there was no significant association with gender (P = 0.065). The Odds Ratio, shown in Table 3, demonstrates that the muscular strength obtained by the manual grip and leg traction did not result in an association with the presence of any region with pain symptomatology. Lumbar traction, which demonstrated that the strongest quartile has a lower association with the presence of pain, and the chances of the weaker 75% presenting symptoms was 2.47 times more (OR: 3.47 [1.27–9.49]). However, flexibility did not present any association with pain symptomatology (P = 0.517).
Binary logistic regression (Odds Ratio): Association between physical fitness and musculoskeletal pain
*All values were adjusted by sex and age.
When considering the main objective of the study, which is to associate strength or flexibility with pain, it was found that individuals with lower lumbar traction strength presented an elevated chance of reporting an anatomical region with pain. It is important to emphasize that this population presents a prevalence of pain of 69.1% and the lumbar region was the most affected region (43.4%).
Analyzing the strength values and following the recommendations proposed by Corbin and Lindsey [31], it can be observed that men presented median, regular, and low values for manual grip, lumbar traction, and leg traction, respectively. For females, manual grip values were median, and regular values were presented for lumbar and leg traction, resulting in values below those recommended for adult populations.
It should be noted that the strength values were below the national reference for a normal population [31]. The lumbar traction strength, for males, for the strongest quartile (>75%), were classified as median, and the weaker quartiles as regular. These results evidenced the same tendency of classification for both sexes and in the different static strengths, demonstrating that workers who perform sedentary activities present relatively low values for different muscle groups.
The description of the results showed that males presented overweight, according to the WHO. In the longitudinal study of Eriksen et al. [32], the authors found a variation in the BMI of workers with a seated occupation, showing a 4% and 3% increase in the frequency of workers with obesity and overweight, respectively. For a population with obesity, muscular weakness is associated with pain. This is occasioned by the excessive fatigue suffered by the muscle from sustaining the body; in extreme cases this muscle can be affected by necrosis [33]. In addition, a meta- analysis found significant associations between obesity and overweight with low back pain; the results indicated that populations with obesity have 0.8 more chances of developing low back pain, while for overweight populations these chances are 50% [34].
The frequency of lumbar pain in our study was 43.4% in relation to the 76 university agents that reported pain, presenting values close to the study by Vitta et al. [4], which showed that populations with a sedentary occupation, similar to our study, presented a frequency of 40% of pain in this region. This same study pointed out that individuals who spend their working hours in a seated position are 2.4 times more likely (OR: 3.40 [1.59–7.26]) to present some painful symptomatology. These findings were similar to those of lumbar strength in the present study, which could indicate an association between work position and muscular strength. Reid et al. [35] demonstrate that spending long hours in a sitting position is associated with lower muscle strength and inversely associated with lean mass percentage.
The results of the present study demonstrate that the target population presents, in the majority, pain and lower strength in the lumbar region. This could be justified by the excess time that this population spends seated, with a time load of up to 12 hours [15]. Corroborating with our findings, Park et al. [36] show that long sitting hours (>7 hours) is an independent association factor for low back pain. Likewise, the presence of low back pain results in lower production of lumbar extension force, which may be related to greater fatigability or atrophy of the lumbar muscles [37,38, 37,38].
The present study demonstrates that the odds of experiencing pain are 247% higher for individuals with lower lumbar strength. This indicates that, when performing an individualized intervention for this population, the focus should be on specific exercises to strengthen the symptomatic region, including exercises with a preventive or therapeutic action [37]. Steele et al., [38] demonstrated that resistance exercises are effective for the control and decrease in pain perception.
As a strong point, the study presents important results for populations with predominantly sedentary labor activities; these results can be used to develop intervention plans and, consequently, reduce cases of pain, which may result in lower rates of leavers or absences and an increase in productivity.
Limitations
The limitations of the present study include the self-reported nature type of study and the lack of values for experience in the job and time spent in job postures. As this is not a longitudinal study, a cause and effect relationship cannot be presented, however, according to the study of Bauman et al. [39], cross-sectional studies are possible mediators of intervention plans.
Conclusion
Given the above, 7 in every 10 of these workers reported some type of musculoskeletal pain, mostly in the lumbar region, demonstrating that low levels of lumbar traction strength may be a factor associated with painful symptomatology. Thus, strengthening weakened regions may result in the prevention of this outcome.
Conflict of interest
None to report.