Acute effects of stochastic resonance whole body vibration

Table 1 Descriptive study results (mean ± SD)

	Baseline	Sham SR-WBV(2 Hz, noise level 0)	Verum SR-WBV(6 Hz, noise level 4)
EMG TD (%MVC)	3.43 ± 2.08	5.68 ± 2.78	9.14 ± 5.81
HRV (mean RMSSD, ms)	38.28 ± 19.76	28.07 ± 26.81	26.14 ± 17.38
Energy expenditure (kcal)	13.67 ± 3.41	18.52 ± 2.96	35.48 ± 5.69
Blood flow (perfusion units)
Neck	27.83 ± 9.22	27.86 ± 11.05	30.81 ± 20.62
Middle back	22.25 ± 6.04	26.33 ± 7.82	27.13 ± 12.45
Lower back	15.40 ± 5.15	14.92 ± 6.22	15.87 ± 6.04
Skin temp (°C)
Neck	34.48 ± 0.85	35.27 ± 1.04	35.65 ± 0.81
Middle back	33.95 ± 0.99	34.85 ± 1.30	35.19 ± 0.91
Lower back	33.90 ± 1.34	34.19 ± 1.35	34.25 ± 1.32
Skin redness (colour unit)
Neck	8.56 ± 2.37	8.83 ± 2.75	8.91 ± 2.58
Middle back	6.39 ± 1.63	7.20 ± 2.03	7.25 ± 2.27
Lower back	6.55 ± 1.74	6.34 ± 1.61	6.41 ± 1.94
CPG pain	1.52 ± 0.75	1.33 ± 0.58	1.33 ± 0.91
Stiffness	2.52 ± 2.16	1.95 ± 1.72	1.76 ± 1.67
Well-being	8.10 ± 1.34	8.24 ± 1.04	8.14 ± 1.71
Muscle relaxation	6.67 ± 1.74	7.24 ± 1.95	8.38 ± 0.97

EMG: Electromyography, activation expressed as percentage of activation measured at maximal voluntary contraction (%MVC) of the decending part of the trapezius muscle (TD); RMSSD: Root of the mean of the sum of the squares of the differences; HRV: Heart rate variability; CPG: Chronic pain grade; SR-WBV: Stochastic resonance whole body vibration.

Table 2 Results of repeated measurement analyses of variance

	df1	F	P	η2	BL vs Sham		BL vs Verum		Sham vs Verum
						P3		P3		P3
EMG TD (%MVC)	1.26	20.19	< 0.001	0.50	2.24 ± 0.48	< 0.001	5.71 ± 1.14	< 0.001	3.37 ± 0.97	0.006
HRV (mean RMSSD, msec)	1.54	6.73	< 0.001	0.25	-10.21 ± 4.41	0.094	12.14 ± 3.25	0.004	1.93 ± 2.83	1.000
Energy expenditure (kcal)	1.56	199.90	< 0.001	0.91	4.86 ± 0.81	< 0.001	21.81 ± 1.30	< 0.001	16.95 ± 1.19	< 0.001
Blood flow (AU)	1.42	0.42	0.591	0.02	0.03 ± 2.31	1.000	2.98 ± 4.04	1.000	2.95 ± 4.48	1.000
Middle back	2.00	18.93	< 0.001	0.49	-4.08 ± 1.91	0.136	7.33 ± 1.58	< 0.001	11.41 ± 2.11	< 0.001
Lower back	1.56	0.35	0.655	0.02	-0.48 ± 0.92	1.000	0.48 ± 1.04	1.000	0.95 ± 1.41	1.000
Skin temperature (°C)	2.00	23.79	< 0.001	0.54	0.79 ± 0.18	< 0.001	1.17 ± 0.18	< 0.001	0.38 ± 0.16	0.075
Middle back	1.36	27.98	< 0.001	0.58	0.90 ± 0.19	< 0.001	1.24 ± 0.10	< 0.001	0.34 ± 0.21	0.348
Lower back	1.55	1.74	0.197	0.08	0.29 ± 0.18	0.390	0.35 ± 0.25	0.515	0.07 ± 0.16	1.000
Skin redness (colour unit)	2.00	0.58	0.565	0.03	0.27 ± 0.30	1.000	0.35 ± 0.32	0.889	0.08 ± 0.38	1.000
Middle back	2.00	4.19	0.022	0.17	0.81 ± 0.38	0.130	0.86 ± 0.25	0.008	0.05 ± 0.36	1.000
Lower back	2.00	0.93	0.404	0.04	-0.20 ± 0.11	0.257	-0.14 ± 0.17	1.000	0.07 ± 0.16	1.000
CPG pain	1.55	1.49	0.240	0.07	0.19 ± 0.09	0.127	0.19 ± 0.15	0.641	0.00 ± 0.14	1.000
CPG stiffness	1.33	5.65	0.018	0.22	0.57 ± 0.29	0.187	0.76 ± 0.30	0.023	0.19 ± 0.13	1.000
CPG well-being	1.31	0.09	0.828	0.01	0.14 ± 0.19	1.000	0.05 ± 0.41	1.000	0.10 ± 0.42	1.000
CPG muscle relaxation	2.00	10.32	< 0.001	0.34	0.57 ± 0.45	0.657	1.71 ± 0.33	< 0.001	1.14 ± 0.36	0.014

¹If the sphericity is not given the Greenhouse-Geisser correction was applied; ³Bonferroni correction applied for post hoc tests. EMG: Electromyography, activation expressed as percentage of activation measured at maximal voluntary contraction ± %MVC) of the decending part of the trapezius muscle ± TD); HRV: Heart rate variability; CPG: Chronic pain grade; RMSSD: The square root of the mean of the sum of the squares of the differences.