Relaxing on a bed of nails: an exploratory study of the effects on the autonomic, cardiovascular, and respiratory systems, and saliva cortisol.

OBJECTIVES: This study investigated subjective and physiologic responses of lying on a bed of nails (BN) called the Shakti-mat and of listening to relaxing instructions and music. The BN has 6210 sharp-edge 5-mm plastic nails about 5 mm apart. DESIGN: Thirty-two (32) healthy participants went through four conditions in randomized orders combining BN and relaxing instructions. RESULTS: The subjective pain ratings on the BN increased immediately and reached a peak within 30 seconds. The pain then subsided gradually, indicating a habituation effect. Self-rated relaxation increased over time in all conditions. Systolic and diastolic blood pressures were higher, heart rate was slower, and there was more high-frequency power heart rate variability (HRV), and signs of increasing circulation in the back on the BN. The relaxation instruction especially affected breathing and the HRV-indices standard deviations of normal interbeat intervals and low-frequency power, both known to be responsive to slow breathing. There were no differences in saliva cortisol. CONCLUSIONS: Healthy participants habituated to the induced pain on the BN and were able to subjectively relax. When on a BN, signs of both sympathetic and parasympathetic nervous system activity were observed. The pain may hypothetically have triggered a parasympathetic response.

Therapeutic massage of the neck and shoulders produces changes in peripheral blood flow when assessed with dynamic infrared thermography.

OBJECTIVE: This study's objective was to determine the effect of therapeutic massage on peripheral blood flow utilizing dynamic infrared thermography in a constant temperature/humidity thermal chamber to assess noncontact skin temperature. DESIGN: The design was a repeated-measures crossover experimental design; the independent variable was treatment condition (massage, light touch, control). SETTING: The study setting was a university research laboratory. SUBJECTS: Seventeen (17) healthy volunteers (8 males/9 females; age = 23.29 +/- 3.06) took part in the study. INTERVENTIONS: One (1) 20-minute neck and shoulder therapeutic massage treatment was performed for each of the three treatment conditions. OUTCOME MEASURES: The dependent variable was noncontact, mean skin temperature in 15 regions measured at 6 time points (pretest and 15, 25, 35, 45, and 60 minutes post-test) for each treatment condition. RESULTS: The massage treatment produced significant elevations in temperature in five regions: anterior upper chest (p = 0.04), posterior neck (p = 0.0006), upper back (p = 0.0005), posterior right arm (p = 0.03), and middle back (p = 0.02). Massage therapy produced significant increases in temperature over time, compared to the other conditions, in the anterior upper chest, and posterior neck, upper back, right arm, and the middle back. Additionally, the temperatures remained above baseline levels after 60 minutes. Interestingly, the massage treatment produced significant temperature elevations in two nonmassaged areas posterior right arm and middle back. CONCLUSIONS: These changes in temperature suggest corresponding changes in peripheral blood flow in the treated areas as well as in adjacent not-massaged areas. Moreover, the results suggest dynamic infrared thermography as a useful tool to measure noninvasive, noncontact changes in peripheral blood flow for massage therapy research.