Independent effects of diet and exercise training on fat oxidation in non-alcoholic fatty liver disease

Table 1 Characteristics of the study groups at baseline (pre-intervention) and after 6 mo of energy restriction or exercise training (post-intervention)

	Energy restriction (n = 6)		Exercise training (n = 10)
	Pre	Post	Pre	Post
Age (yr)	45.5 ± 13.5		51.8 ± 6.7
Gender (M:F)	3:3		7:3
BMI (kg/m2)	33.5 ± 9.0	30.0 ± 7.0a	31.2 ± 3.2	30.8 ± 3.5
Fat-mass (%)	38 ± 9	35 ± 11b	36 ± 7	33 ± 6a
Fat-free mass (kg)	54.1 ± 12.3	51.3 ± 11.8	63.1 ± 14.3	64.4 ± 14.2a
Waist (cm)	106 ± 16	90 ± 13	110 ± 14	105 ± 13a
Systolic blood pressure (mmHg)	126 ± 13	118 ± 13a	139 ± 19	137 ± 18
Subcutaneous adipose tissue (cm2)	358 ± 282	268 ± 202b	322 ± 116	298 ± 117a
Visceral adipose tissue (cm2)	202 ± 110	203 ± 56b	182 ± 67	117 ± 36a
Diastolic blood pressure (mmHg)	83 ± 8	75 ± 12	88 ± 11	83 ± 10
Triglycerides (mmol/L)	1.6 ± 0.8	1.1 ± 0.4	2.0 ± 1.3	2.0 ± 0.2
HDL cholesterol (mmol/L)	0.9 ± 0.2	1.0 ± 0.3	1.0 ± 0.2	1.1 ± 0.2a
LDL cholesterol (mmol/L)	3.5 ± 0.8	3.0 ± 0.6	3.2 ± 1.1	3.1 ± 1.0
VLDL cholesterol (mmol/L)	0.7 ± 0.3	0.5 ± 0.2b	0.9 ± 0.6	0.7 ± 0.5
Free fatty acids (mmol/L)	0.59 ± 0.15	0.63 ± 0.23	0.59 ± 0.17	0.62 ± 0.25
Glucose (mmol/L)	5.2 ± 0.3	5.0 ± 0.7	5.5 ± 0.5	5.3 ± 0.4
Insulin (mU/L)	18 ± 18	10 ± 5	24 ± 23	12 ± 10
M-value (mg/kgFFM per minute)	4.2 ± 1.4	5.2 ± 1.5	4.0 ± 0.9	5.2 ± 1.6a
hsCPR (mg/L)	4.9 ± 3.7	2.0 ± 1.6	3.9 ± 3.6	1.5 ± 1.3
Alanine aminotransferase (U/L	80 ± 65	55 ± 55	54 ± 19	49 ± 28
Aspartate aminotransferase (U/L)	40 ± 22	28 ± 16	38 ± 11	39 ± 22

Complete-case analysis performed.

^aP < 0.05, within group difference in reponse to the intervention;

^bP value < 0.10, within group trend in reponse to the intervention. Pre-intervention there was no difference between energy restriction and exercise groups in any of the parameters presented (P > 0.05). M:F: Male:Female; BMI: Body mass index; HDL: High density lipoprotein; LDL: Low density lipoprotein; VLDL: Very low density lipoprotein; hsCRP: High sensitivity C reactive protein.

Table 2 Resting substrate metabolism pre-intervention and after 6 mo of energy restriction or exercise training (post-intervention) in patients with non-alcoholic fatty liver disease

	Energy restriction (n = 6)			Exercise (n = 10)
	Pre	Post	P	Pre	Post	P
Respiratory quotient	0.82 ± 0.04	0.80 ± 0.04	0.38	0.84 ± 0.06	0.81 ± 0.06	0.05
Fatox (mg/kgFFM per minute)	1.18 ± 0.25	1.46 ± 0.33	0.17	1.15 ± 0.54	1.35 ± 0.48	0.08
CHOox (mg/kgFFM per minute)	2.33 ± 0.69	1.72 ± 0.83	0.19	2.70 ± 1.24	1.90 ± 1.17	0.02

Complete-case analysis performed. Fat_ox: Fat oxidation rates; CHO_ox: Carbohydrate oxidation rates; FFM: Fat-free mass.

Table 3 Change in substrate metabolism from basal (resting and fasting) to insulin-stimulation conditions pre-intervention and after 6 mo of energy restriction or exercise training (post-intervention)

	Energy restriction (n = 6)			Exercise (n = 10)
	Pre	Post	P	Pre	Post	P
Δ Respiratory quotient	0.05 ± 0.05	0.08 ± 0.05	0.58	0.04 ± 0.02	0.07 ± 0.05	0.11
Δ Fatox (mg/kgFFM per minute)	-0.29 ± 0.46	-0.56 ± 0.32	0.31	-0.24 ± 0.36	-0.55 ± 0.35	0.06
Δ CHOox (mg/kgFFM per minute)	0.92 ± 0.98	1.41 ± 0.98	0.46	0.54 ± 0.85	1.02 ± 0.93	0.18

Complete-case analysis performed. Fat_ox: Fat oxidation rates; CHO_ox: Carbohydrate oxidation rates; FFM: Fat-free mass; Δ: Change from basal to insulin-stimulated condition.

Table 4 Maximal aerobic power and substrate oxidation during exercise pre-intervention, and after 6 mo of energy restriction or exercise treatment (post-intervention)

	Energy restriction (n = 6)			Exercise (n = 10)
	Pre	Post	P	Pre	Post	P
VO2peak (mL/kg per minute)	20.4 ± 5.1	20.7 ± 6.4	0.73	23.9 ± 6.4	28.3 ± 6.3	< 0.001
VO2peak (mL/kgFFM per minute)	32.5 ± 5.0	31.0 ± 5.4	0.31	39.2 ± 8.4	43.6 ± 7.4	0.004
Workload at VO2peak (W)	121 ± 53	121 ± 57	0.94	176 ± 78	224 ± 81	< 0.001
MFO (g/min)	0.14 ± 0.13	0.06 ± 0.04	0.17	0.17 ± 0.09	0.29 ± 0.14	0.03
MFO (mg/kgFFM per minute)	2.5 ± 1.7	1.2 ± 0.7	0.18	2.8 ± 1.5	4.4 ± 1.9	0.04
Workload at MFO (W)	44.8 ± 16.5	41.3 ± 13.4	0.43	44.7 ± 19.5	76.3 ± 46.0	0.03
Fatmax (%VO2peak)	48.7 ± 14.7	47.9 ± 8.8	0.62	45.2 ± 12.3	47.0 ± 7.2	0.94

Complete-case analysis performed. VO_2peak: Peak oxygen uptake; MFO: Maximal fat oxidation; W: Watts; Fat_max: Exercise intensity eliciting maximal fat oxidation; FFM: Fat-free mass.