Correlation between vitamin D levels and muscle fatigue risk factors based on physical activity in healthy older adults

Figures & data

Table 1 General characteristics of subjects based on level of PA

Parameters	Physically inactive (≤500 METs min/week)	Moderate PA (500–2,500 METs min/week)	Physically active (≥2,500 METs min/week)
N	25	25	35
Male/female	10/15	16/9	22/13
Age (years)	62.7±4.3	63.2±5.6	62.9±3.7
BMI (kg/m^2)	26.1±7.6	23.4±6.3*	18.9±4.3*
Waist (cm)	76.1±27.9	69.7±18.5	64.6±16.5
Hips (cm)	85.9±24.3	85.7±22.3	85.4±21.7
Systolic BP (mmHg)	111.2±9.5	108.9±10.3	109.5±10.5
Diastolic BP (mmHg)	72.5±13.7	72.5±11.3	72.8±8.5
Glucose (mmol/L)	5.7±0.85	5.4±0.65**	4.8±0.75**
TG (mmol/L)	0.85±0.45	0.81±0.65*	0.8±0.41*
Total cholesterol (mmol/L)	4.3±0.56	4.2±0.68*	3.9±0.98*
HDL-cholesterol (mmol/L)	1.5±0.35	1.2±0.30*	1.0±0.28*
LDL-cholesterol (mmol/L)	3.6±0.72	3.4±0.67*	3.0±0.61*

Notes: Values are expressed as mean ± SD;

* P<0.05,

** P<0.01. Significance at P<0.05.

Abbreviations: BMI, body mass index; BP, blood pressure; HDL, high-density lipoprotein; LDL, low-density lipoprotein; MET, metabolic equivalent; PA, physical activity; TG, triglyceride; SD, standard deviation.

Table 2 Change in muscle fatigue biomarkers, 25(OH) vitamin D, serum calcium, TAC, and mean pain scores (VAS) of subjects based on level of PA (mean ± SD)

Parameters	Physically inactive, N=25 (≤500 METs min/week)	Moderate PA, N=25 (500–2,500 METs min/week)	Physically active, N=35 (≥2,500 METs min/week)
25(OH) vitamin D (nmol/L)	23.8±2.9	48.6±4.8**	62.3±7.61***
sTCa^2+ (mmol/L)	1.9±0.56	2.50±4**	5.70±4.1***
sf-Ca^2+ (mmol/L)	1.1±0.7	1.6±0.2**	2.7±0.2***
CK (UI/L)	309.8±7.9	276.3±3.7**	245.1±5.3***
LDH (IU/L)	65.3±11.6	48.5±7.1**	32.8±4.9***
Troponin I (ng/mL)	1.9±0.18	1.16±0.12**	0.82±0.05***
Hydroxyproline (ng/mL)	3.9±0.15	2.65±0.21**	1.75±0.31***
TAC (nmol/μL)	16.5±6.3	22.9±11.7**	38.3±13.8***
VAS score	55.3±20.5	36.7±12.3**	22.4±9.3***

Notes: Values are expressed as mean ± SD;

** P<0.01,

*** P<0.001. Significance at P<0.05.

Abbreviations: CK, creatine kinase; LDH, lactate dehydrogenase; MET, metabolic equivalent; PA, physical activity; SD, standard deviation; sf-Ca²⁺, serum-free calcium; sTCa²⁺, serum total calcium; TAC, total antioxidant capacity; VAS, visual analog scale.

Table 3 Bivariate associations of 25(OH) vitamin D to various parameters based on PA

Parameters	Physically inactive, N=25 (≤500 METs min/week)	Moderate PA, N=25 (500–2,500 METs min/week)	Physically active, N=35 (≥2,500 METs min/week)
BMI (kg/m^2)	−0.28*	−0.2*	−0.18*
WC (cm)	−0.011*	−0.14*	−0.21**
Hips (cm)	−0.07*	−0.25*	−0.59**
Glucose (mmol/L)	−0.014*	−0.27*	−0.31**
TG (mmol/L)	−0.041*	−0.59*	−0.72**
Total cholesterol (mmol/L)	−0.09*	−0.085*	−0.067**
HDL-cholesterol (mmol/L)	−0.011*	−0.017*	−0.021**
LDL-cholesterol (mmol/L)	−0.006*	−0.015*	−0.031**
sTCa^2+ (mmol/L)	0.042*	0.051*	0.038**
sf-Ca^2+ (mmol/L)	0.016*	0.035*	0.046**
CK (UI/L)	−0.21*	−0.25*	−0.29**
LDH (IU/L)	−0.34*	−0.51*	−0.37**
Troponin I (ng/mL)	−0.61*	−0.47*	−0.54**
Hydroxyproline (ng/mL)	−0.27*	−0.35*	−0.47**
TAC (nmol/μL)	0.32*	0.41*	0.59**
VAS score	−0.12*	−0.15*	−0.17**
PA score	0.23*	0.52*	0.71**

Note: Data presented as coefficient (R);

* Denotes significance at <0.05;

** Denotes significance at <0.01.

Abbreviations: BMI, body mass index; CK, creatine kinase; HDL, high-density lipoprotein; LDL, low-density lipoprotein; LDH, lactic acid dehydrogenase; MET, metabolic equivalent; PA, physical activity; sf-Ca²⁺, serum-free calcium; sTCa²⁺, serum total calcium; TAC, total antioxidant capacity; TG, triglyceride; VAS, visual analog scale; WC, waist circumference.

Table 4 Beta coefficients and cumulative R²* values derived from stepwise multiple regression models

Parameters	Muscle fatigue (VAS score, 0–100 mm)
	Mild (5–44)		Moderate (45–74)		Severe (75–100)
	R^2* (β)	95% CI	R^2* (β)	95% CI	R^2* (β)	95% CI
Body weight (kg)	22.5 (0.42)	85 (60–87)	18.2 (0.22)	95 (86–100)	16.9 (0.32)	86 (81–100)
Age (years)	12.1 (0.65)	75 (60–95)	17.4 (0.35)	94 (87–100)	10.2 (0.55)	94 (85–98)
BMI (kg/m^2)	7.5 (0.25)	94 (86–98)	7.5 (0.15)	90 (73–97)	6.9 (0.25)	89 (87–100)
Vitamin D (nmol/L)	24.1 (0.25)	82 (75–97)	14.1 (0.45)	76 (72–100)	11.8 (0.85)	94 (73–98)
Calcium (mg/dL)	9.3 (0.44)	82 (75–97)	5.8 (0.24)	89 (87–100)	6.1 (0.34)	95 (88–100)
Physical activity level (MET min/week)	6.9 (0.25)	85 (56–96)	2.5 (0.75)	95 (88–100)	3.8 (0.49)	90 (46–95)
TAC (nmol/μL)	3.4 (0.25)	94 (72–100)	8.6 (0.65)	89 (87–100)	5.7 (0.48)	69 (52–96)
ΣR^2 (%)	85.8	96 (87–100)	74.1	95 (88–100)	61.4	90 (46–95)

Note:

* P<0.05.

Abbreviations: BMI, body mass index; CI, confidence interval; MET, metabolic equivalent; TAC, total antioxidant capacity; VAS, visual analog scale.