Effects of Urban Afforestation Activity on Thermal and Mechanical Pain Mechanisms: a Clinical Trial

Cold pain tolerance threshold

时间窗: Change from baseline cold pain tolerance threshold after 90 minutes.

Cold pressor test will be employed (3±1°C). Participants will be instructed to submerge their nondominant hand in the cold water as long as they can endure the pain. Elapsed time in seconds will be recorded for the analysis as cold pain tolerance threshold. A cut-off time of 4 minutes is determined.

Pressure pain intensity ratings

时间窗: Change from baseline pressure pain intensity ratings after 90 minutes.

The same instrument as in the pressure pain detection thresholds will be utilised. This time, nail of the dominant thumb will be subjected to two separate pressure levels, 294 kPa and 490 kPa, to obtain pressure pain intensity ratings. Upon reaching the aimed level, the pressure will be maintained for 2 seconds. Thereafter, participants will be asked to rate the evoked pain sensation by using the 101-point Numeric Rating Scale. Those who are unable to tolerate these pressure levels will be excluded from the analysis and handled as missing data. This procedure will be repeated three times. The average of the second and third measurements will be recorded as pressure pain ratings.

Pressure pain tolerance thresholds

时间窗: Change from baseline pressure pain tolerance threshold after 90 minutes.

The maximum pressure at which the participant defines the ongoing pain as intolerable is defined as the pressure pain tolerance threshold. A similar procedure as the detection thresholds will be adapted and followed this time for the mid-point of the upper border of the trapezius muscle and the nail cuticle of the ring finger on the nondominant side of participants. Average of the second and third measurements will be recorded as pressure pain tolerance threshold.

Cold pain detection threshold

时间窗: Change from baseline cold pain detection threshold after 90 minutes.

Cold pressor test will be employed (3±1°C). Participants will be instructed to submerge their nondominant hand in the cold water and report the initial occurrence of pain. Elapsed time in seconds will be recorded for the analysis as cold pain detection threshold. A cut-off time of 4 minutes is determined.

Cold pain intensity ratings

时间窗: Change from baseline cold pain intensity ratings after 90 minutes.

Cold pressor test will be employed (3±1°C). Cold pain intensities will be measured by asking the participants to report their maximal pain intensities by using the 101-point Numeric Rating Scale once the cold detection and tolerance thresholds are reached.

Wind-up ratio

时间窗: Change from baseline wind-up ratio after 90 minutes.

A response-dependent mechanical temporal summation method will be implemented by utilising a pinprick mechanical stimulator (256 mN). A single stimulus will be applied to the L2-L5 paraspinal muscles of the nondominant side and the participant will be asked to rate the pain intensity on the 101-point Numeric Rating Scale. After an interval of 10 seconds, a train of 10 stimuli will be applied on the same point with a mean cadence of 2 stimuli per second. This time the participant will be asked to rate the overall intensity of pain evoked by the stimuli series. The pain rating of the stimuli series will be divided by that of the single punctuation. This value will be recorded as the wind-up ratio.

Mechanical pain sensitivity

时间窗: Change from baseline mechanical pain sensitivity after 90 minutes.

The mechanical pain sensitivity of the participants' facial area will be assessed by using the same pinprick stimulator as for the wind-up ratio. A 2-sec pinprick stimulus will be applied on both cheeks three times. The interstimulus interval will be 10 seconds. Participants will be asked to rate the perceived pain intensity after each stimulus by using the 101-point Numeric Rating Scale. In case the participant does not report any pain, the minimum value of zero will be registered. A mean value of three measurements will be recorded as mechanical pain sensitivity.

Pressure pain detection thresholds

时间窗: Change from baseline pressure pain detection threshold after 90 minutes.

A hand-held dial pressure algometer device with the standard method of limits will be utilised. The application sites will consist of the muscle belly of the tibialis anterior and the middle of the dorsal aspect of the wrist joint line on the dominant side of participants. The patients will be asked to report the primary pain sensation to the evaluator. The value will be recorded in kg. A cut-off value of 1000 kPa is determined for safety reasons. A total of three measurements will be obtained at each site. Average of the second and third measurements will be recorded as pressure pain detection threshold.