The Impact of Insomnia on Pain Sensitivity and the Trajectory of Exercise-induced Muscular Pain

Muscle pain will be measured by an 11-point NRS, with 0 represents "no pain" and 10 indicating "worst imaginable pain". The Outcome will be recorded at rest, reach for the floor with knees straight, and during a validated hamstring provocative manoeuvre, the "taking-off shoe" test.

Muscle soreness will be measured by an 7-point Likert scale, with 0= A complete absence of soreness," 1 = "A light soreness in the muscle felt only when touched/a vague ache," 2 = "A moderate soreness felt only when touched/a slight persistent pain," 3 = "A light muscle soreness when walking up and down stairs," 4 = "A light muscle soreness when walking on flat surface," 5 = "A moderate muscle soreness, stiffness, or weakness when walking," 6 = "A severe muscle soreness, stiffness, or weakness that limits my ability to move."

Thermal thresholds will be measured with a 30 × 30 mm thermode (TSA 2, Medoc Ltd., Ramat Yishai, Israel). The thermode will be placed gently on the skin without causing deformation. Using the method of limits, temperature will increase or decrease at 1℃/second within a 0 - 51℃ range, with a baseline temperature of 32℃. Participants will press the stop button when the thermal sensation first becomes painful. The mean value of five consecutive trials will be used in the analysis.

Mechanical pain threshold will be evaluated using standardised weighted pinprick stimulators (MRC System GmbH, Heidelberg, Germany) with a 0.25mm flat contact area. Seven fixed intensities (8 mN - 512 mN) will be applied. The final threshold will be calculated as the geometric mean of the ascending and descending stimulus intensities from five series.

Pressure pain threshold will be assessed with a digital pressure algometer (Medoc Ltd., Ramat Yishai, Israel) equipped with a 1 cm2 rubber probe. Pressure will be applied at 30 Kpa per second until participants perceive painful. Three trials will be performed, and the mean scores will be calculated to determine the PPT.

The pinprick stimulator will assess TSP-M at 256 mN. Ten stimuli will be delivered at 1-second intervals over a 1 cm2 area. Pain intensity will be rated on an 11-point NRS after the first and the 10th stimuli. If the NRS pain rating remains 0 out of 10 for three consecutive 256 mN stimuli, intensity will be increased to 512 mN, and the trial will be repeated. TSP-M will be calculated as the NRS difference between the first stimulus and the 10th stimulus.

TSP-H will be measured with a 9 cm2 thermode (TSA 2, Medoc Ltd., Ramat Yishai, Israel). Two sequences of 10 heat pulses at 46 ℃ and 48 ℃ will be delivered with a 5-minute interval. Each pulse has a 0.5 s duration and will be delivered from a 40 ˚C baseline at a 13°C/s ramp rate and 2.5 s interstimulus interval. The participant will rate pain intensity on an 11-point NRS after each stimulus. TSP-H will be defined as the NRS difference between the 10th stimulus and the first stimulus for each temperature.

CPM will be evaluated using a noxious conditioning stimulus (CS) and a test stimulus (TS). The CS will be contact heat applied to the dominant volar forearm between the distal third of the forearm and the ulnar styloid. Temperature will be set 1.1 °C above the participant's HPT for 120s, starting from 32 ℃ with an 8°C/s ramp using the TSA 2 device (Medoc Ltd., Ramat Yishai, Israel). During the CPM assessment, if participants could not tolerate the CS (i.e., pain intensity over 8 on the11-point NPRS) or if they reported a pain intensity below 4 on the 11-point NPRS, the temperature of the CS will be adjusted to ensure a safe and adequate stimulus intensity. The TS will be applied to the thenar eminence of the non-dominant hand using a pressure algometer (Medoc Ltd., Ramat Yishai, Israel) to determine PPT before and immediately after the CS. The CPM effect will be calculated by subtracting the PPT measured before the CS from the PPT measured after the CS.

The ISI is a 7-item self-report questionnaire assessing the nature, severity, and impact of insomnia. Each item is rated on a 5-point Likert scale (0 to 4). The total score ranges from 0 to 28, with higher scores indicating greater severity of insomnia

The PSQI is a 19-item self-report questionnaire that evaluates sleep quality and disturbances over a 1-month time interval. It generates seven component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. Each component is scored from 0 to 3. The sum of these seven component scores yields a global PSQI score ranging from 0 to 21, where higher scores indicate poorer sleep quality.

Assessed using a daily consensus sleep diary. Total Sleep Time is calculated as the total time spent asleep, derived from the total time in bed (bedtime to rise time) minus sleep onset latency and wake after sleep onset. Higher values indicate longer sleep duration.

Assessed using a daily consensus sleep diary. Sleep Onset Latency is the estimated time (in minutes) it takes to fall asleep after turning off the lights. Lower values indicate better sleep onset.

Assessed using a daily consensus sleep diary. WASO is calculated as the total duration of wakefulness (in minutes) between initial sleep onset and final awakening, derived from the number of night awakenings multiplied by their average duration. Lower values indicate better sleep continuity.

Assessed using a daily consensus sleep diary. Sleep Efficiency is calculated as the percentage of time in bed spent asleep: [(Total Sleep Time / Total Time in Bed) × 100]. Total Sleep Time is derived from total time in bed (time between bedtime and rise time) minus sleep onset latency and nocturnal wakefulness (calculated from the number and duration of night awakenings). Scores range from 0% to 100%, with higher percentages indicating better sleep quality.

Measured objectively using a wrist-worn ActiGraph accelerometer and validated sleep-scoring algorithms. Total Sleep Time is defined as the total amount of time spent sleeping between bedtime and rise time. Higher values indicate longer sleep duration.

Measured objectively using a wrist-worn ActiGraph accelerometer. Sleep Onset Latency is defined as the period of time (in minutes) between the initial bedtime (lights out) and the onset of continuous sleep detected by the algorithm. Lower values indicate faster sleep onset and better sleep initiation.

Measured objectively using a wrist-worn ActiGraph accelerometer. WASO is defined as the total number of minutes spent awake after initial sleep onset and before final awakening, as determined by epoch-by-epoch movement counts. Lower values indicate better sleep continuity and fewer night awakenings.

Measured objectively using a wrist-worn ActiGraph accelerometer. Sleep Efficiency is calculated as the percentage of time in bed spent asleep: [(Total Sleep Time / Total Time in Bed) × 100]. Values range from 0% to 100%, with higher percentages indicating better sleep quality and efficiency.

Assessed using the 21-item Depression Anxiety Stress Scales (DASS-21). The instrument consists of three 7-item subscales measuring depression, anxiety, and stress. Each item is rated on a 4-point Likert scale ranging from 0 ("did not apply to me at all") to 3 ("applied to me very much or most of the time"). Sum scores for each subscale are calculated and multiplied by 2 to yield total scores ranging from 0 to 42 for each dimension (Depression: 0-42, Anxiety: 0-42, Stress: 0-42), with a total overall score ranging from 0 to 126. Higher scores indicate greater levels of psychological distress/severity.

Assessed using the 13-item Pain Catastrophizing Scale (PCS) to evaluate catastrophic thoughts and feelings associated with pain (comprising rumination, magnification, and helplessness subscales). Each item is rated on a 5-point Likert scale from 0 ("not at all") to 4 ("all the time"). The total score ranges from 0 to 52, with higher scores indicating higher levels of pain catastrophizing.

Assessed using the 9-item short form of the Fear of Pain Questionnaire (FPQ-9) to assess fear of different painful experiences across severe pain, minor pain, and medical pain domains. Each item is rated on a 5-point Likert scale from 1 ("not at all") to 5 ("extreme"). The total score ranges from 9 to 45, with higher scores indicating greater fear of pain.

Assessed using the 11-item Tampa Scale for Kinesiophobia (TSK-11) to evaluate fear of movement or (re)injury. Each item is scored on a 4-point Likert scale ranging from 1 ("strongly disagree") to 4 ("strongly agree"). The total score ranges from 11 to 44, with higher scores indicating greater fear of movement/kinesiophobia.

Assessed using the 7-item International Physical Activity Questionnaire - Short Form (IPAQ-SF). The questionnaire measures the duration (minutes) and frequency (days) of walking, moderate-intensity activities, and vigorous-intensity activities performed over the last 7 days. Total physical activity volume is calculated as MET-minutes per week (MET-min/week) using standardised MET energy expenditure values: Walking = 3.3 METs, Moderate PA = 4.0 METs, and Vigorous PA = 8.0 METs. Total score is the sum of (METs × minutes × days) across all three domains, with scores starting from 0 and no strict upper limit. Higher scores indicate higher levels of overall physical activity.