Effects of 12-Week Combined Strength and Endurance Circuit Training Program on Insulin Sensitivity and Retinol-Binding Protein 4 in Women with Insulin-Resistance and Overweight or Mild Obesity: A Randomized Controlled Trial

Figures & data

Table 1 Training Plan

Resistance Training Load		Endurance Training Intensity
Sessions 1–8	50% of 1RM	Sessions 1–8	50% of HRR
Sessions 9–16	60% of 1RM	Sessions 9–16	60% of HRR
Sessions 16–24	70% of 1RM	Sessions 16–36	75% of HRR
Sessions 25–36	80% of 1RM

Abbreviations: 1RM, one-repetition maximum; HRR, heart rate reserve.

Table 2 Pre-Study Demographic and Clinical Characteristics of Participants in the Training (T) and Non-Training (NT) Groups

	T Group	NT Group	p-value
	(n=19)	(n=8)
Age [years]	33.37±4.5	32.13±5.1	0.534^a
Body mass [kg]	79.72±9.4	79.39±5.0	0.927^a
BMI [kg/m^2]	28.79±3.2	28.18±1.5	0.604^a
Insulin [µU/mL]	13.17±3.8	12.30±5.3	0.276^a
Insulin after 2h [µU/mL]	96.72±70.8	49.75±23.6	0.367^a
HBA1c [%]	5.26±0.3	5.16±0.3	0.418^a
Hypothyroidism (n)	10	3	0.470^b

Notes: ^aStudent’s t-test, ^bMaximum likelihood chi-squared test.

Figure 1 Study flow chart.

Table 3 Factors Controlled During the Study

		T Group	NT Group	ANOVA
		MEAN±SD (n=19)	MEAN±SD (N=8)	Group Effect p value (ƞ^2)	Time Effect p value (ƞ^2)	Group x Time p value (ƞ^2)
Energy intake [kcal/day]	PRE	1682.0±469.9	1695.2±313.1	0.594 (0.01)	0.747 (0.01)	0.224 (0.06)
	DURING	1764.0±421.3	1555.3±410.8
Protein intake [g/day]	PRE	78.1±19.4	69.4±14.9	0.212 (0.07)	0.501 (0.02)	0.810 (0.00)
	DURING	80.5±11.8	74.4±22.5
Fat intake [g/day]	PRE	70.1±21.6	58.9±16.3	0.172 (0.08)	0.804 (0.00)	0.942 (0.00)
	DURING	71.3±18.2	59.5±16.4
Carbohydrates intake [g/day]	PRE	205.7±76.2	226.7±32.2	0.908 (0.00)	0.138 (0.09)	0.255 (0.06)
	DURING	200.1±69.1	185.5±54.7
Physical activity (MET/min/week)	PRE	1665±1726	2864±2242	0.916 (0.00)	0.710 (0.01)	0.004 (0.29)
	DURING	3111±2950*	1722±1907

Notes: Bold indicate significant (p < 0.05); *Post-hoc p<0.05 (difference between pre to post intervention in the particular group).

Table 4 Pre- and Post-Study Physiological and Body Composition Indicators in the Training and Non-Training Groups

		T Group	NT Group	ANOVA
		MEAN±SD (n=19)	MEAN±SD (N=8)	Group Effect p value (ƞ^2)	Time Effect p value (ƞ^2)	Group x Time p value (ƞ^2)
1 RM abdominal crunch [kg]	PRE	21.7±5.1	22.0±5.5	0.051 (0.14)	0.000 (0.38)	0.000 (0.53)
	POST	28.8±4.3**	20.9±4.6
Resting heart rate [bpm]	PRE	85.61±10.7	74.25±8.4	0.278 (0.05)	0.043 (0.16)	0.010 (0.25)
	POST	74.37±11.3**	75.88±14.4
Systolic blood pressure [mmHg]	PRE	120.67±14.8	120.38±12.6	0.978 (0.00)	0.147 (0.09)	0.892 (0.00)
	POST	115.74±13.8	116.13±11.6
Diastolic blood pressure [mmHg]	PRE	82.67±11.1	78.88±9.1	0.282 (0.05)	0.301 (0.04)	0.961 (0.00)
	POST	80.53±7.9	76.38±11.5
Body mass [kg]	PRE	79.72±9.4	79.39±5.0	0.769 (0.00)	0.421 (0.03)	0.186 (0.07)
	POST	80.87±9.7	79.10±4.8
Visceral Adipose Tissue [g]	PRE	1033±491	993±461	0.937 (0.00)	0.787 (0.80)	0.571 (0.00)
	POST	997±468	1006±431
Total Fat Mass [kg]	PRE	34.32±6.3	32.35±3.2	0.436 (0.03)	0.562 (0.01)	0.830 (0.00)
	POST	34.46±6.6	32.64±3.3
Total Lean Mass [kg]	PRE	43.11±3.8	44.77±2.6	0.530 (0.02)	0.752 (0.00)	0.039 (0.24)
	POST	43.95±3.8*	44.11±2.2

Notes: Bold indicate significant (p < 0.05); **Post-hoc p<0.01, *Post-hoc p<0.05 (difference between pre to post intervention in the particular group).

Abbreviation: 1RM, one repetition maximum test.

Table 5 Pre- and Post-Study Biochemical Indicators in the Training and Non-Training Groups

		T Group	NT Group	ANOVA
		MEAN±SD (n=19)	MEAN±SD (N=8)	Group Effect p value (ƞ^2)	Time Effect p value (ƞ^2)	Group x Time p value (ƞ^2)
Glucose [mmol/L]	PRE	5.30±0.4	5.26±0.3	0.495 (0.02)	0.473 (0.04)	0.629 (0.04)
	POST	5.30±0.5	5.11±0.2
Insulin [µU/mL]	PRE	13.17±3.8	12.30±5.3	0.397 (0.02)	0.532 (0.02)	0.543 (0.01)
	POST	14.70±6.3	12.60±9.0
HOMA-IR	PRE	3.08±0.9	2.85±1.1	0.397 (0.03)	0.532 (0.02)	0.543 (0.02)
	POST	3.46±1.5	2.86±2.0
Total cholesterol [mmol/L]	PRE	4.98±0.6	4.97±0.7	0.403 (0.03)	0.695 (0.01)	0.122 (0.15)
	POST	4.71±0.6	5.16±0.9
HDL-cholesterol [mmol/L]	PRE	1.40±0.3	1.30±0.2	0.460 (0.02)	0.253 (0.05)	0.431 (0.03)
	POST	1.41±0.3	1.37±0.2
LDL-cholesterol [mmol/L]	PRE	3.20±0.7	3.49±0.8	0.196 (0.07)	0.165 (0.08)	0.145 (0.08)
	POST	2.96±0.7	3.48±0.9
Triglycerides [mmol/L]	PRE	1.25±0.3	1.19±0.3	0.548 (0.02)	0.032 (0.17)	0.238 (0.06)
	POST	1.39±0.5	1.65±0.9
TSH [uIU/mL]	PRE	1.79±0.9	1.94±1.1	0.852 (0.00)	0.083 (0.12)	0.357 (0.03)
	POST	2.46±1.2	2.15±1.5
IGF-1 [ng/mL]	PRE	20.66±13.0	23.64±13.3	0.666 (0.01)	0.046 (0.16)	0.328 (0.04)
	POST	20.03±13.0	21.87±12.5
RBP4 [mg/mL]	PRE	62.09±23.7	78.56±26.1	0.106 (0.11)	0.068 (0.13)	0.923 (0.00)
	POST	55.85±25.1	71.66±19.6

Note: Bold indicate significant (p < 0.05).

Abbreviations: HOMA-IR, homeostasis model assessment of insulin resistance; TSH, thyroid-stimulating hormone; IGF-1, insulin-like growth factors-1; RBP4, retinol-binding protein-4.

Figure 2 Spearman correlation between retinol binding protein- 4 and thyroid- stimulating hormone concentration before the intervention.