Effect of stimulation of cold receptors with menthol on EMG activity of quadriceps muscle during low load contraction

Figures & data

Table 1. Characteristics of subjects.

	Adult Placebo	Adult Menthol	Older Adult Menthol	One-way ANOVA
	Data (n = 15)	Data (n = 15)	Data (n = 12)	p-value
Male (%)	100	100	100	–
Age (years)	23.5 ± 5.0	21.5 ± 0.6	63.1 ± 2.6	p < .01
Height (cm)	171.4 ± 5.4	170.7 ± 6.0	167.2 ± 3.4	.09
Weight (kg)	65.2 ± 5.8	66.4 ± 11.5	66.0 ± 6.0	.94
BMI (kg/m^2)	22.2 ± 1.7	22.7 ± 3.0	23.6 ± 3.0	.38
Body fat ratio (%)	15.6 ± 5.0	17.0 ± 4.5	23.4 ± 5.3	p < .01
Skeletal muscle mass of all (kg)	31.0 ± 2.1	30.9 ± 4.7	27.7 ± 3.0	.03
Skeletal muscle mass of right leg (kg)	8.8 ± 0.7	8.7 ± 1.3	8.3 ± 1.2	.39

Data are mean ± SD.

Figure 1. Experimental protocol. MVC: maximum voluntary contraction.

Figure 2. Experimental setup. Subjects sat on an adjustable chair-like device and the lower leg was attached to a plate connected to a torque meter.

Table 2. MVC force and rmsEMG.

Variables	Adult Placebo	Adult Menthol	Older Adult Menthol	One-way ANOVA p-value
MVC (Nm)	195.1 ± 44.9	186.1 ± 55.3	157.2 ± 47.9	.14
rmsEMG (μV)
Vastus lateralis (VL)	159.7 ± 52.3	124.7 ± 57.3	110.8 ± 65.3	.08
Rectus femoris (RF)	177.7 ± 59.0	193.0 ± 128.3	94.4 ± 51.4	p < .05
Vastus medialis (VM)	201.1 ± 129.0	238.5 ± 145.9	141.4 ± 92.7	.15

Data are mean ± SD.

Table 3. Subjective cold sensation intensity.

Scale	Adult Placebo	Adult Menthol	Older AdultMenthol
0. not cold	0	0	0
1. a little cold	6	0	1
2. somewhat cold	7	0	3
3. cold	2	9	2
4. very cold	0	4	6
5. too cold and painful	0	2	0
Total	15	15	12

Table 4. Changes in rmsEMG and MPF with menthol during 35% MVC.

		Adult Placebo		Adult Menthol		Older Adult Menthol		Main effect
		Control	Placebo	Control	Menthol	Control	Menthol	Condition	Group	Interaction
rmsEMG (μV)
VL		39.5 ± 3.2	40.4 ± 3.5	32.1 ± 4.3	36.1 ± 5.4**	46.4 ± 6.1	50.2 ± 9.9**	p < .01	p < .01	p < .01
%		25.2 ± 1.3	25.7 ± 1.4	26.5 ± 1.6	29.3 ± 2.0	39.8 ± 3.1	43.2 ± 3.2
RF		38.2 ± 5.3	40.9 ± 6.5	31.6 ± 3.3	33.6 ± 3.3	24.8 ± 3.4	26.5 ± 3.8	p < .05	0.07	0.91
%		21.6 ± 2.3	22.8 ± 2.6	22.0 ± 2.9	23.4 ± 3.1	30.5 ± 3.4	32.3 ± 3.7
VM		27.9 ± 3.2	28.6 ± 3.2	39.4 ± 5.3	45.7 ± 6.7**	44.1 ± 7.6	48.7 ± 8.1**	p < .01	p < .01	p < .01
%		16.4 ± 1.7	16.9 ± 1.8	18.2 ± 1.6	20.8 ± 1.9	34.2 ± 4.8	37.5 ± 4.8
MPF (Hz)
VL		134.7 ± 8.9	132.9 ± 8.7	145.3 ± 4.9	147.8 ± 5.3	104.2 ± 5.9	101.1 ± 5.9	0.38	p < .01	p < .05
RF		103.7 ± 2.7	101.9 ± 2.5	101.6 ± 2.2	99.6 ± 2.2	94.0 ± 6.6	91.1 ± 6.3	p < .01	0.16	0.85
VM		105.8 ± 6.1	104.1 ± 5.8	103.2 ± 4.9	101.5 ± 4.8	95.4 ± 7.0	92.9 ± 7.1*	p < .01	0.43	0.84

Data are mean ± SE. rmsEMG (μV) is shown in the upper row and normalized rmsEMG (% MVC) is shown in the lower row. VL: vastus lateralis, RF: rectus femoris, VM: vastus medialis. Two-way ANOVA was used in the statistical analysis of Main effect and Interaction.

*,**Significant difference between conditions in group (p < .05, p < .01, respectively) using Bonferroni post hoc test.

Figure 3. Changes in rmsEMG (A) and MPF (B) with menthol stimulation. VL: vastus lateralis, RF: rectus femoris, VM: vastus medialis. Data are mean ± SE. *^,**Significant difference between groups (p < .05, p < .01, respectively) using Bonferroni post hoc test.