Table 2 Characteristics of studies included in this systematic review

Almenning et al. [32]

(RCT)

HIIT: 10/8

RT: 11/8

CON: 10/9

10 wks (baseline, 10 wks)

Age: 27.2 ± 5.5 y

BMI: 26.7 ± 6.0 kg/m²

(Rotterdam)

HIIT frequency: 3 times/wk

HIIT intensity: 2 d/wk, 4 × 4 mins 90–95% HR_max/3 × 3 mins ~ 70% HR_max. 1 d/wk, 10 × 1 min ‘all-out’/10 × 1 min rest.

RT frequency: 3 times/wk

RT sets × reps: 3 × 10

RT load: 75% 1-RM

HOMA-IR, FBG, FI, TG, TC, LDL-C, HDL-C VO₂ max, RHR, BW, BMI, WC, BF%, FM, FFM, T, SHBG, FAI, hsCRP

Brown et al. [97]

(RCT)

EX: 21/8

CON: 16/12

20–24 wks due to varying length of ramp-up phase

(baseline, immediately post)

Age: 32.3 ± ns y

BMI: 33.0 kg/m²

(NIH)

Exercise: 12-wk moderate-intensity intervention preceded by 8–12-wk ramp-up.

Aerobic duration: ~ 228 min/wk (≤ 60 bouts)

Aerobic intensity: 40–60% VO₂ max

FBG, FI, HOMA-IR, TG, LDL-C, HDL-C, VO₂ max, BW, BMI, WC, FT, SBP, DBP

Bruner et al. [98]

(RCT)

EX + DIET: 7/7

DIET: 5/5

12 wks

(baseline, 12 weeks)

Age: 30.7 ± 4.6 y

BMI: 36.6 ± 6.0 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Aerobic intensity: 70–85% HR_max

Aerobic duration: 30 mins (+ 10-min warm-up)

RT sets × reps: 2–3 × 10–15

RT load: not specified

Diet: 1 h/wk of nutritional counselling

FI, QUICKI, VO₂ max, BW, BMI, WC, T, SHBG, FAI

Guzick et al. [99]

(RCT)

EX + DIET: 6/6

CON: 6/6

12 wks

(baseline, 12 weeks)

Age: 31.7 ± 10.0 y

BMI: ns

(NIH)

Exercise frequency: 5 times/wk

Exercise intensity: 1050–4200 kJ/wk

Diet: VLCD (8 wks) with calories increased over final 4 wks (4200–5040 kJ/d).

‘Optifast’ used to supplement diet

FBG, FI, BW, WHR, T, SHBG, FT, LH, FSH

Hoeger et al. [100]

(RCT)

LS + PLA: 11/6

PLA: 9/7

LS + MF: 9/5

MF: 9/5

48 wks

(baseline, 24 wks, 48 wks)

Age: 28.5 ± 5.2 y

BMI: 39.0 ± 6.1 kg/m²

(NIH)

Exercise programme: Individualised to achieve 150 min per week

Diet: Individualised healthy balanced meal plan to achieve 500–1000 kcal deficit per day

Metformin: 850 mg 2 times/day

BW, T, SHBG, FAI

Konopka et al. [102]

(RCT)

EX: 12/12

CON: 13/13

12 wks

(baseline, 12 wks)

Age: 35 ± 5.0 y

BMI: 33.0 ± 5.0 kg/m²

(Rotterdam)

Exercise frequency: 5 times/wk

Exercise intensity: 65% VO₂ peak

Exercise duration: 60 min

FBG, FI, HOMA-IR, BMI, BW, FM, FFM, E₂

Nasrekani et al. [104]

(RCT)

EX: 10/10

CON: 10/10

12 wks

(baseline, 12 wks)

Age: 30.4 ± 5.9 y

BMI: 28.3 ± 6.2 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Exercise intensity: 40–65% HR_max

Exercise duration: 25–30 min

VO₂ max, BW, BMI, FSH, LH

Nybacka et al. [105, 106]

(RCT)

EX: 19/17

EX + DIET: 19/12

DIET: 19/14

4 months

(baseline, 4 months)

Age: 30.8 ± 5.2 y

BMI: 36.0 ± 6.2 kg/m²

(Rotterdam)

Exercise programme: Individualised to meet individuals’ capacity, goals and interest.

Diet: ≥ 600 kcal/day reduction maintaining 55–60% CHO, 25–30% fat and 10–15% protein.

FBG, FI, HOMA-IR, BW, BMI, WHR, BF%, FFM, T, SHBG, FT, E₂, FSH, LH

Petranyi et al. [107]

(QRCT)

LS + MF: 29/29

MF: 27/27

6 months

(baseline, 6 months)

Age: 29 ± ns y

BMI: 27.2 ± 6.9 kg/m²

(Rotterdam)

Exercise programme: recommendation to increase physical activity levels. Specifics unclear.

Diet: low glycaemic index diet with caloric restriction for those who are obese.

Metformin: 500 mg 3 times/day

BMI, WHR

Roessler et al. [34]

(Randomised crossover)

EX: 8/7

CON: 9/7

16 wks

(baseline, 8 wks, 16 wks)

Age: 31.7 ± 7.9 y

BMI: 36.3 ± 7.2 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk (2 × cycle, 1 × walk)

Exercise intensity: following 2-week ramp, cycling 20–180 s 80–100% HR_max/rest 25–180 s 45–65% HR_max. Walking 3–5 min 80–90% HR_max/1 min 50–60% HR_max.

Exercise duration: 45 min (+ 10 min warm-up).

Control: Group counselling sessions (2 h, 1 time/wk) focussing on barriers and motivation.

VO₂ max, BW, BMI, WC

Sa et al. [36, 108]

(RCT)

EX: 15/14

CON: 15/13

16 wks

(baseline, 16 wks)

Age: 26.0 ± 5.0 y

BMI: 32.8 ± 4.6 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Exercise intensity: 60–85% HR_max

Exercise duration: 40 min (+ 5 min)

SBP, DBP, FI, BMI, RHR, VO₂ max, T, FSH, LH

Saremi et al. [109]

(RCT)

EX: 11/11

CON: 11/11

8 wks

(baseline, 8 wks)

Age: 35.2 ± 4.4 y

BMI: 28.3 ± 4.3 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Exercise intensity: 40–65% HR_max

Exercise duration: 30 min

FBG, FI, HOMA-IR, TG, TC, LDL-C, HDL-C, VO₂ peak, BW, BMI, BF%, WC, WHR

Saremi et al. [110]

(RCT)

EX + PLA: 10/10

CON: 10/10

EX + CAL: 10/10

8 wks

(baseline, 8 wks)

Age: 27.1 ± 5.1 y

BMI: 25.5 ± 2.7 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

RT sets x reps: 1–2 × 15–20

RT load: 40–60% 1-RM

FBG, FI, HOMA-IR, TG, TC, LDL-C, HDL-C, BW, BMI

Stener-Victorin et al. [101, 103, 111,112,113]

(RCT)

EX: 34/22

CON: 17/13

ACU: 33/24

16 wks

(baseline, 16 wks, 32 wks)

Age: 30 ± 4.4 y

BMI: 28.1 ± 7.3 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Exercise intensity: HR ≥ 120 BPM

Exercise duration: 30–45 min

Low-frequency electroacupuncture: 14 × 30 min treatments over 16 wks

SBP, DBP, FBG, FI, HOMA-IR, TG, TC, LDL-C, HDL-C, BMI, WHR, T, FT, SHBG, FAI, LH, FSH,

VO₂ max, BMI, E₂

Thomson et al. [33, 114,115,116]

(RCT)

AET + DIET: 31/18

AET + RT + DIET: 33/20

DIET: 30/14

20 weeks (baseline, 10 wks, 20 wks)

Age: 29.3 ± 6.8 y

BMI: 36.1 ± 4.8 kg/m²

(Rotterdam)

Exercise frequency: 5 times/wk (3 × aerobic, 2 × RT in combined exercise group)

Aerobic intensity: 60–65% HR_max progressed to 75–80% HR_max by study end

Aerobic duration: 25–30 min progressed to 45 mins by study end

RT sets × reps: 3 × 12

RT load: 50–60% 1-RM progressed to 65–75% 1-RM after 2 wks

Diet: energy restricted high protein diet (5000–6000 kJ/day)

SBP, DBP, FBG, FI, HOMA-IR, TG, TC, LDL-C, HDL-C, BW, BF%, FM, FFM, WC, T, SHBG, FAI, PCOS-Q

Turan et al. [117]

(RCT)

EX: 16/14

CON: 16/16

8 wks

(baseline, 8 wks)

Age: 24.5 ± 2.8 y

BMI: 21.9 ± 3.5 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Exercise duration: 50–60 min

Aerobic intensity: 65–70% HR_max

RT sets x reps: 1 × 15

RT load: 5–6 on RPE for RT scale

SBP, DBP, FBG, HOMA-IR, FI, TG, TC, HDL-C, LDL-C, BMI, WC, RHR, VO₂ max, T, FT, E₂, LH, FSH

Vigorito et al. [118]

(RCT)

EX: 45/45

CON: 45/45

3 months

(baseline, 3 months)

Age: 21.8 ± 2.1 y

BMI: 29.4 ± 3.2 kg/m²

(Rotterdam)

Exercise frequency: 3 times/wk

Exercise intensity: 60–70% VO₂ max

Exercise duration: 30 min

SBP, DBP, FBG, FI, TG, TC, LDL-C, HDL-C, VO₂ max, RHR, BMI, WC, E₂, T, FT, SHBG, FAI, LH, FSH, CRP

Vizza et al. [119]

(RCT)

EX: 8/7

CON: 7/6

12 wks

(baseline, 12 wks)

Age: 27 ± 5.0 y

BMI: 37.8 ± 11.4 kg/m²

Exercise frequency: 4 times/wk (2 × RT, 2 home-based)

RT sets × reps: 2–3 × 8–12

RT load: Progressed with strength gains

Home-based: Callisthenics, 3 sets of 10 reps

FBG, FI, HOMA-IR, BW, BMI, WC, FM, FFM, BF%, hsCRP, T, SHBG, FAI, PCOS-Q, SF-36