Resistance training program for fatigue management in the workplace: exercise protocol in a cluster randomized controlled trial

Fatigue is a nonspecific symptom associated with chronic health problems and functional deterioration at work. It is complex and multidimensional and varies in intensity depending on the imposed overload [1–9]. Workplace fatigue is a common complaint that requires attention due to its high prevalence and its association with serious dysfunctions among workers [5]. It affects physical and mental health [3, 9], increasing the chance of accidents and musculoskeletal complaints [10], and reducing performance and productivity [4].

The symptoms of fatigue are due to individual characteristics [5, 6] as well as to work factors involving physical and mental demands, such as lack of planning with regard to work activities, rosters, and work shifts; environmental conditions; and standing for long periods [9]. Factors related to fatigue outside the workplace are sedentary behavior, lifestyle, and unhealthy diet, all of which build up over time [9]. Fatigue can be mental, due to prolonged periods of high cognitive demands along with the physical activity imposed by the daily load of highly physical jobs [7, 9]. Acute fatigue is a normal phenomenon in healthy workers and it is reversed after a period of rest [2]; however, chronic fatigue is more severe and often cannot be reversed simply by reducing workloads or resting [3, 6, 8]. The effects of fatigue on worker health and job performance can be short term or long term [2, 3, 6]. The short-term effects are reduced attention span, poor decision-making, reduced alertness, and poor control of emotions [3]. Fatigue can also increase the rate of mistakes, reduce reaction times, and elevate the likelihood of accidents and injuries [11]. The long-term effects are heart disease, diabetes, high blood pressure, gastrointestinal disorders, sleep loss, depression, and anxiety [2].

Fatigue contributes to the occurrence of musculoskeletal disorders, which represent a major problem for the health of workers worldwide [4, 5]. Workplace characteristics, repetitive tasks, static contractions, and inadequate posture are associated with the majority of structural disorders and the development of fatigue [10]. Various organizational aspects of work have been associated with a variety of adverse health effects, especially occupational disorders such as fatigue [10]. Thus, it becomes crucial to adopt measures for evaluating and managing these organic dysfunctions manifested as the development of fatigue [7]. Exercise programs have been widely used for fatigue management and pain relief, and to improve muscle strength, flexibility, and cardiovascular conditioning [12–15].

Exercise has been shown to have highly beneficial effects on physical and mental health [16], promoting significant changes to lifestyle and wellbeing [17]. It has a great impact on the health of all individuals, reducing mortality rates and increasing life expectancy [12, 13], as well as improving function in the musculoskeletal, blood, cardiopulmonary, immune, and nervous systems [12, 18]. Furthermore, it can reduce many of the risk factors for non-communicable chronic diseases (hypertension, cholesterol levels, diabetes), as well as percentage of body fat and body mass index [18, 19].

Exercise at the workplace has positive effects on the health of workers and is most effective when done in a group because there is more motivation thus increasing adherence to the program [20]. There is strong evidence of the effectiveness of strength training at the workplace for reducing musculoskeletal complaints in specific regions of the body [20–24]. A variety of strength training protocols are described in the literature, including protocols to decrease pain in the cervical, lumbar, and shoulder areas; low-intensity training; high-intensity training with concentric contractions; high-intensity training with isometric contractions; and highly intensive training (HIT) [20–22, 25]. However, there is consensus that resistance exercises are more effective [20, 25], and 20-min training sessions [20–25] 3 times a week for periods of 10 weeks or more [20, 23] reduce musculoskeletal complaints in the workplace. The protocol of heavy resistance exercise at the workplace includes exercise with higher intensity in eccentric and concentric contractions, using dumbbells, elastic bands, and exercises against gravity [20]. The effectiveness of medium- and long-term progressive resistance exercise programs with progressive loads for muscle strength gain and fatigue reduction has already been shown in the literature [18, 21], with most studies being cross-sectional in nature. In contrast, the small number of longitudinal studies that describe the benefits of resistance training for fatigue management in the workplace hinders decision-making regarding interventions for this population. Therefore, the advantage of this study is its randomized clinical trial design in the occupational context, with control of all of the variables that simulate the gym environment.

The hypothesis investigated in this study is that the physical load, high work demand, and absence of breaks imposed on production workers can contribute to an increase in the need for recovery due to increased symptoms of fatigue. It is understood that improving the workers’ physical conditioning is essential to managing the symptoms of fatigue at the workplace. To achieve that, resistance training with progressive loads is the most effective program.

Thus, our objective in this study is demonstrate a resistance exercise protocol to be performed at the workplace during the work schedule, and to describe the procedure that will be used to evaluate the effectiveness of this program in fatigue management for industrial workers.