The Efficacy of an Exercise Program and a Yoga Program in Mitigating Stress and Improving Mental Health Among Employees

Insomnia level by the Insomnia severity index. This self-report scale, developed by Morin (1993), assesses the severity of insomnia based on the diagnostic criteria of the DSM-IV and the International Classification of Sleep Disorders (ICSD). It consists of seven items evaluating the type and severity of insomnia over the past two weeks, including sleep satisfaction, daytime functioning impairment, sleep-related difficulties, and distress caused by sleep problems. The total score ranges from 0 to 28, with scores of 8 to 14 indicating mild insomnia, 15 to 21 indicating moderate clinical insomnia, and 22 or above indicating severe insomnia.

To measure the level of PTSD symptoms in study participants, we will use the PTSD Checklist for DSM-5 (PCL-5), developed by Weathers et al. (2013), based on the diagnostic criteria of the DSM-5. The PCL-5 is an adaptation of the PTSD Checklist (PCL), originally created by Weathers et al. (1993), and was translated by Park et al. (2016) and validated by Lee et al. (2020). The PCL-5 assesses the severity of symptoms experienced over the past month due to a past traumatic event. It consists of 20 items rated on a 5-point Likert scale (0 = Not at all, 4 = Extremely), with higher scores indicating more severe PTSD symptoms. The PCL-5 includes subscales for intrusion, avoidance, negative alterations in cognition and mood, and hyperarousal. The provisional cutoff score is known to be between 31 and 33, with a cutoff of 25.5 identified in a validation study of the general Korean adult population (Lee et al., 2022; Bovin et al., 2016).

This tool is the shortened version of the Korean Occupational Stress Scale (KOSS), originally consisting of 43 items, now reduced to 24 items. Each item is rated on a 5-point Likert scale ranging from 1 (Not at all) to 5 (Very much). Higher scores indicate higher levels of job stress experienced over the past month. The scale covers seven domains: job demands, job autonomy, job insecurity, interpersonal conflict, organizational system, inadequate compensation, and workplace culture. It was designed for easy application in field settings (Jang Se-jin et al., 2005).

To measure the current level of job burnout in the study participants, we will use the Maslach Burnout Inventory-General Survey (MBI-GS), developed by Schaufeli et al. (1996) to assess burnout in general workers, and adapted and validated by Shin Kang-hyun (2003). This scale evaluates the three core dimensions of burnout syndrome experienced in the workplace: exhaustion, cynicism, and professional efficacy. Each dimension consists of five items, rated on a 7-point Likert scale from 0 (strongly disagree) to 6 (strongly agree). Higher scores in the exhaustion and cynicism dimensions, and lower scores in the professional efficacy dimension, indicate greater levels of job burnout.

To measure participants\' positive and negative affect, we will use the revised Korean version of the Positive and Negative Affect Schedule (K-PANAS-R). This scale was originally developed by Watson et al. (1988) and was validated in Korean by Lee Hyun-hee et al. (2003). Park Hong-seok et al. (2016) reviewed its limitations and revised the scale through translation and back-translation of the original. The K-PANAS-R assesses emotions experienced by participants over the past week using 20 items, each rated on a 5-point Likert scale, reflecting the intensity of the emotions described by the adjectives.

To assess baseline physical fitness levels, the following tests, as recommended by the Korean Society of Sports Science, were conducted and the respective results were recorded: flexibility, muscle strength, knee push-up, gait test, and balance test.

For measuring neural activity in the prefrontal lobe, we will use a 2-channel EEG (FP1, FP2). EEG is a non-invasive method that quantifies brain electrical activity by attaching electrodes to the scalp to capture electrical signals generated by potential differences. This method is non-invasive, offers excellent temporal resolution, and is cost-effective, making it widely applicable in studies involving general populations. The raw data collected by the device are processed using TeleScan (© Laxtha, Inc.) to calculate absolute power, frequency ratio, relative power, and symmetry across different frequency bands. The key indicators derived from the data include: Theta, Alpha, Low-Beta, Mid-Beta, High-Beta, Gamma, the (Low-Beta + Mid-Beta)/Theta power ratio, and the Alpha/High-Beta power ratio.

Heart rate variability (HRV) is an effective method for quantitatively assessing autonomic nervous system activity and balance. It is widely used to examine changes in autonomic activity and balance caused by stress, as well as to gather information on stress-related disorders. HRV can be analyzed using various methods, with time domain analysis and frequency domain analysis being the most commonly employed. In this study, we will use several frequently used indicators from frequency domain analysis in HRV research, including: TP (total power), LF (low frequency), HF (high frequency), and the LF/HF+LF ratio.