Abstract
BACKGROUND:
There are many potential training exercises for office workers in an attempt to prevent musculoskeletal disorders. However, to date a suitable tool to monitor the perceived exertion of those exercises does not exist.
OBJECTIVE:
The primary objective of this study was to examine the validity and reliability of the Borg CR-10 scale to monitor the perceived exertion of office exercise training.
METHODS:
The study involved 105 staff members employed in a government office with an age range from 25 to 50 years. The Borg CR-10 scale was self-administered two times, with an interval of two weeks in order to evaluate the accuracy of the original findings with a retest. Face validity and content validity were also examined.
RESULTS:
Reliability was found to be high for the Borg CR-10 scale (0.898). Additionally a high correlation between the Borg CR-10 scale and Visual Analog Scale (VAS) was identified (rs = 0.754, P < 0.01).
CONCLUSIONS:
This study found the Borg CR-10 scale to be a reliable and valid tool for monitoring the perceived exertion of office exercise training and may potentially be useful for occupational therapists to measure physical activity intensity levels.
Introduction
Musculoskeletal disorders (MSDs) are often associated with a lack of adequate physical activity [1]. As a result of the lack of attention on the working conditions of office workers from both the employers and local organizations, the prevalence of MSDs is on the rise [2]. Office-based exercise programs have been found to be effective in reducing MSDs [3].
Despite a tremendous advancement in technology, the monitoring of office exercise training’s intensity remains a major problem to occupational therapists, physical therapists, and researchers. In endurance training researchers are able to monitor exercise intensity by measuring physiological parameters such as the percentage of VO2max, blood lactate concentration [4], and percentage of max heart rate [5]. However, there has been no single accepted method to monitor how ‘hard’ sedentary office employees are working during an office exercise training session. A measurement of intensity is needed to monitor progress and gather information how to increase the load where the current practice of using traditional quantified objective measurements is not adequate [6].
Questionnaires and training diaries provide valuable information regarding office exercise training sessions [2]. However, this area of study has received little attention from exercise scientists, particularly in regard to office exercise training [2, 7]. For office workers, training for treatment or prevention, the use of volume of training is an inadequate tool because of the short duration and low frequency of office exercise training [2, 6]. In general, the effects of office exercise training are related to the type of exercise used and its volume [7]. Although, both exercise type and the volume could be determined based on therapist or researcher experience and understanding, it is necessary to identify a method to monitor training intensity using a valid and reliable approach. Office exercise training represents a complex milieu of perceptual signals including the type of exercise used, all of which interacts with the type of office exercise protocol because the nature of office work requires sitting for prolonged periods of time and office workers are relatively sedentary individuals [8]. Defining intensity and training volume in office exercise is a composite of the number of sets and repetitions, and the duration of each single exercise [9, 10]. This is an important difference from other types of training where the total duration of exercise in minutes is the appropriate volume of measurement. If one considers intensity to show how ‘hard’ the exercise or workout, then other factors such as rest periods between sets, number of repetitions completed in each set, and speed of the exercise need to be included [11, 12]. The combination of all these factors will certainly and clearly gauge how ‘hard’ or intense the perceived exercise. In addition, incorporation of other variables such as the training status of the individual exercising and the impact of residual fatigue during hard periods of training will make the measurement process even more complicated.
The Borg Rating of Perceived Exertion (RPE) may be a practical means of measuring office-based physical activity intensity level. The CR-10 scale of the Borg is a category scale with ratio properties containing numbers associated to verbal expressions; these permit comparison between the rate and the levels of intensity in clinical and sport settings [2, 14]. The application has mainly been used during aerobic exercise, but recently a number of investigators have studied the use of Borg CR-10 scale with other types of training [15, 16]. Several studies have demonstrated that the Borg CR-10 scale serves as an effective method of quantifying different types of exercise training [2, 12]. The Borg CR-10 was also used by Brandt et al. in 2014 [17] to approximate the intensity of elastic resistance and isotonic machines targeting the hip abductor muscle compared to EMG findings. Brandt et al. categorized Borg scale’s findings as light (Borg ≤2), moderate (Borg >2–<5), heavy (Borg≥5–<7) and near maximum (Borg≥7), and found that that the link between EMG findings and the Borg CR-10 increased from moderate to high [17].
In the current study RPE was incorporated to encourage office workers to rate the training session globally and to simplify the myriad exercise intensity cues during the exercise process [2]. Perceived exertion is how hard they perceive their body is working and the rating can be determined using the Borg scale. This allows researchers or the therapists to evaluate trends in training, injury, and illness in relation to the RPE and the global intensity of the exercise session [12, 13]. The aim of this current analysis is to examine the reliability and validity of the Borg CR-10 scale for rating perceived exertion (RPE) that can be used to monitor the intensity of office exercise training. We hypothesize that the Borg CR-10 is a reliable and valid scale to measure office-based exercise training intensity level.
Methods
Sample size
With an ideal confidence interval (CI) rate of 95% at 0.2 in width, an approximate 0.75 in intraclass correlation coefficient (ICC) and a suggested drop-out rate of 25%, the reliability and validity of the sample size was thus evaluated with reference to “Sample Size Tables for Clinical Studies” [20]. Therefore 105 subjects were selected through the aforementioned pattern of calculation for reliability testing.
Participants
Participants were included if they were an office worker who worked at least 8 hours a day in front of a computer. Both sexes were eligible to participate in this study. Subjects had to be 25–50 years old with the ability to complete questionnaires. They were not eligible for the study if they had comorbidities which impacted their basic physical activities. The study was conducted in a Malaysian government office. All procedures were carried out in tandem with the 1964 Helsinki Declaration and before the study was conducted all participants provided written consent [21].
Protocol of exercise
The exercise protocol contained thirteen exercises adopted from McKenzie’s exercises [22], William’s exercises [23], and guidelines of American College of Sports Medicine (ACSM) [24], which have been sequenced in a manner most suitable to alleviate pain in the lower back, neck and shoulders among office workers [6]. As the participants became tired during the 15 minutes exercise, we collected changes in their perceived exertion and used the Borg scale after 5, 10, and 15 minutes of exercise training.
Data collection
The data collection was conducted between February 2015 and April 2015. The research assistants received training sessions to administer the Borg CR-10 scale correctly. Participants were asked to not implement any changes to their daily routines while the researchers were collecting data. The participants were educated on the exercise training protocol as well as instructions to complete the questionnaire after exercises were performed by the subjects. Two weeks later, the reliability of the survey questionnaire was evaluated through a second retest of the Borg CR-10 scale.
Reliability
All participants completed the questionnaire twice (in baseline and after two-weeks, in the morning before they start their work) so that the internal consistency and reliability of the Borg CR-10 scale could be assessed. The ICC (inter-class correlation) and Pearson correlation coefficient were used to analyze test–retest reliability. Based on a previous study, related to office workers, a time-span of approximately seven to ten days in length is reported to be a suitable interval between testing [25]. Assessment of reliability was conducted using criteria described by Shrout with values less than 0.10 indicating no agreement; values between 0.11 and 0.40 indicating slight agreement; values between 0.61 and 0.80 indicating moderate agreement and values greater than 0.81 indicating substantial agreement [26].
Validity
Concurrent validity
All participants completed a Visual Analog Scale (VAS) (Fig. 1) so that the validity of the Borg CR-10 could be determined [27]. Participants who reported little or no pain/discomfort in the VAS would respond with “nothing at all” in the Borg CR-10 survey. Those who were experiencing pain and discomfort completed the VAS and subsequently report the Borg CR-10 survey that they were indeed in pain. In order to assess the association between the Borg CR-10 and the VAS, the Spearman correlation coefficient was utilized [25]. Subjects completed both the Borg CR-10 and the VAS after exercise sessions at varying durations of 5, 10 and 15 minutes in length.
Visual Analog Scale (VAS).
Sixty participants were chosen at random and subjected to interviews in order to obtain their personal analysis of the questionnaire. They were asked whether the questions and proposed answers in the questionnaire are precise descriptions of the intensity and pain they experienced while participating in the study.
Statistical analysis
The Spearman correlation coefficient was utilized to evaluate the dependability of the Borg CR-10 in both test and retest situations and the Statistical Package for Social Sciences (SPSS) software (Windows Version 21.0) was used for statistical analysis. To ascertain the relationship between the two scales, Cohen’s κ coefficient and Spearman’s correlation were used.
Results
Demographics
All the 105 individuals (68 male and 37 female) agreed to take part in the study. The mean age of the respondents was 33.7±10.6 years respectively (Table 1).
Demographic characteristics of the study sample
Demographic characteristics of the study sample
Test retest reliability revealed an ICC of 0.898. This indicates that there is substantial test retest reliability of the Borg CR-10 scale [25, 26].
Concurrent validity
There was a significant correlation identified between the Borg CR-10 scale and Visual Analog Scale (rs = 0.754, P < 0.01). Correlation coefficients of 0.712, 0.746 and 0.812 were recorded after 5, 10 and 15 minutes, respectively.
Face validity
Positive feedback was obtained from both participants and two experts (one of them with a PhD degree in Occupational health and the other holding an MD degree in Sports Medicine) regarding clarity, simplicity, order of arrangement and representation of pain and intensity on all sections.
Discussion
The Borg CR-10 is a commonly used method to assess the intensity of exercise by having the patient rate their perceived exertion [28]. This scale has been widely examined for its use in both clinical and exercise settings [2, 29]. The RPE scale has been validated and has become a standard method of measuring the level of intensity experienced during physical activity [29]. The current study found a substantial reliability and acceptable validity for the Borg CR-10 scale in office workers. The scale exhibits test-re-test reliability for low intensity exercise training performed in an office-setting. Furthermore, the results of the current study demonstrate that it is also a valid method for measuring the intensity of exercise in office workers.
This study is one of a few available studies that have investigated the reliability of the Borg CR-10 scale to monitor the perceived exertion of office exercise training.
Our findings are similar to that of other research [15, 24] that has showed an increase in perceived exertion during the time of exercise.
The previously mentioned studies investigated the use of the scale with different exercises, but did not address the scale’s possible use with office exercise. Our results are also in agreement with a number of studies [32, 33] that have shown that a single session RPE rating may accurately reflect the intensity of an exercise session. Day et al. (2004) had 9 men (24.7 +/–3.8 years) and 10 women (22.1 +/–2.6 years) perform resistance exercises with different intensities including: high-intensity (H), moderate-intensity (M), and low-intensity (L) twice [33].
The current study findings also agree with the work of Foster et al. (2001), who emphasized the importance of monitoring training during multiple types of exercise [32]. They conclude that the session RPE method is a valid process of quantified exercise training during a wide variety of types of exercise. Therefore, the RPE method may be a valuable tool to allow for the quantitative evaluation of training periodization plans.
The RPE method uses a fairly simple question: “How was your training session?”. The answer should be provided 30 minutes after the end of the training session, from the Borg’s CR10 scale [34]. The results of this study were similar to those of VAS-M, due to the fact that questionnaires as a method had been considered a legitimized and dependable device with which the intensity of exercise can be measured. This study had some limitations such as generalizability to the type of exercises, population of participants, and the type of office work and should be interpreted with caution.
Conclusion
Exercise training sessions can be monitored with the help of several methods. Among these, perhaps the most legitimate and dependable especially in monitoring the intensity of office exercise is the RPE method by using Borg CR-10 scale. As it only needs a single assessment of workout intensity, the RPE method is therefore an easy to utilize tool. Occupational and physical therapists can rely on this method not only to discern exercise patterns on a weekly basis, but also to collect data to be entered into a training diary.
Conflict of interest
The author(s) declared no potential conflicts of interests with respect to the research, authorship, and/or publication of this article.
Ethical approval
The Department of Occupational Health at the University Putra Malaysia was referred to for the attainment of the ethical approval required for this study.