This randomized, parallel-group study looked at how a standard 15-minute ice pack applied to the back of the hand affects skin temperature and how cold and comfortable the hand feels, compared with a room-temperature water pack. Healthy young men were randomly assigned to one of the two groups during a single laboratory visit. Skin temperature was measured before, during, and after the application, and participants rated their thermal sensation (how cold/warm they felt) and overall comfort. The main outcome was the change in hand skin temperature right after the 15-minute application. Additional outcomes included comfort and cold-feeling ratings and how quickly skin temperature returned toward baseline during recovery. This was a minimal-risk study; expected short-term effects included temporary cold, numbness, redness, or mild discomfort. No medicines or invasive procedures were used.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
39
Single 15-minute application of a reusable plastic Mueller ice bag (Ø 22.86 cm, 946 mL). The bag was filled with 400 g pre-portioned cylindrical ice and placed on the dorsal side of the dominant hand, \~1 cm proximal to the wrist-joint line, fully covering the fingers. Participants were supine with the treated hand slightly elevated; ambient temperature and humidity were controlled (≈22.5 ± 1.0 °C; 55.3 ± 6.5% RH). Subjective thermal sensation/comfort (and pain) were recorded at minutes 7 and 15 during application. Arm: Experimental - Ice Pack
Identical 15-minute application using the same Mueller bag, filled with thermoneutral water (within ±0.5 °C of limb skin temperature), mass-matched to 400 g. Placement, posture, room conditions, and timing of subjective assessments (minutes 7 and 15) mirrored the experimental arm: bag on the dorsal side of the dominant hand, \~1 cm proximal to the wrist-joint line, fully covering the fingers; participants supine with the hand slightly elevated. Arm: Active Comparator - Thermoneutral Water Pack.
Poznan University of Physical Education, Department of Physical Therapy and Sports Recovery
Poznan, Poland
Minimum dorsal-hand skin temperature during rewarming (IV-X), by infrared thermography
Region-of-interest (ROI) mean skin temperature (Tsk; °C) on the dorsal hand measured with infrared thermography (IRT; FLIR SC640). The primary estimand is the between-group mean difference (Ice - Thermoneutral) in the nadir (minimum) across rewarming time points IV-X, with 95% confidence intervals (CI). Lower values indicate greater cooling.
Time frame: From immediately after pack removal (0 minutes; time point IV) to 30 minutes after pack removal (time point X).
IRT-RT temperature offset at matched time points I-X
Difference between infrared-thermography-derived skin temperature (TskIRT) and resistance temperature detector-derived skin temperature (TskRT), in degrees Celsius (°C), at each matched time point (I-X). IRT values represent ROI averages; resistance temperature (RT) values are point skin temperature readings from a RTD placed between the 3rd and 4th metacarpal bones. Positive values indicate that TskIRT is greater than TskRT. Between-group comparisons across time.
Time frame: Baseline (after acclimatisation) and at 0, 5, 10, 15, 20, 25, and 30 minutes after ice-pack removal.
Change in Mechanical Detection Threshold (MDT) from baseline to immediately post (I → IV)
MDT (g) via Semmes-Weinstein monofilaments using an up-down procedure; analysed as IV - I. Higher values indicate reduced tactile sensitivity.
Time frame: Baseline (after acclimatisation; time point I) and 0 minutes after ice-pack removal (time point IV).
Change in Vibration Detection Threshold (VDT) from baseline to immediately post (I → IV)
VDT using a 64-Hz Rydel-Seiffer tuning fork (0-8/8 scale); analysed as IV - I. Higher values indicate reduced vibration sensitivity.
Time frame: Baseline (after acclimatisation; time point I) and 0 minutes after ice-pack removal (time point IV).
Thermal Sensation (TSS) during cooling and immediately post
9-point TSS (-4 very cold … +4 very hot) at I-IV; peak during cooling prespecified as the maximum at II or III. Between-group comparison of peak and trajectory.
Time frame: Baseline (after acclimatisation; time point I), 7 minutes after ice-pack application (time point II), 15 minutes after ice-pack application (time point III), and 0 minutes after ice-pack removal (time point IV).
Thermal Comfort (CS) during cooling and immediately post
5-point comfort scale (1 comfortable … 5 extremely uncomfortable) at I-IV; peak during cooling prespecified as the maximum at II or III.
Time frame: Baseline (after acclimatisation; time point I), 7 minutes after ice-pack application (time point II), 15 minutes after ice-pack application (time point III), and 0 minutes after ice-pack removal (time point IV).
Pain Intensity (Visual Analogue Scale; VAS) during cooling and immediately after ice-pack removal
0-100 mm visual analogue scale; peak during cooling prespecified as the maximum at II or III.
Time frame: Baseline (after acclimatisation; time point I), 7 minutes after ice-pack application (time point II), 15 minutes after ice-pack application (time point III), and 0 minutes after ice-pack removal (time point IV).
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