Effect of exercise training on insulin sensitivity, hyperinsulinemia and ectopic fat in black South African women: a randomized controlled trial

Melony C Fortuin-de Smidt; Amy E Mendham; Jon Hauksson; Olah Hakim; Darko Stefanovski; Louise Clamp; Lindokuhle Phiri; Jeroen Swart; Louise M Goff; Lisa K Micklesfield; Steven E Kahn; Tommy Olsson; Julia H Goedecke

doi:10.1530/EJE-19-0957

Effect of exercise training on insulin sensitivity, hyperinsulinemia and ectopic fat in black South African women: a randomized controlled trial

Melony C Fortuin-de Smidt, Amy E Mendham, Jon Hauksson, Olah Hakim, Darko Stefanovski, Louise Clamp, Lindokuhle Phiri, Jeroen Swart, Louise M Goff, Lisa K Micklesfield, Steven E Kahn, Tommy Olsson, Julia H Goedecke

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Abstract

Objective: We investigated the effects of a 12-week exercise intervention on insulin sensitivity (SI) and hyperinsulinemia and associated changes in regional and ectopic fat.

Research design and methods: Healthy, black South African women with obesity (mean age 23 ± 3.5 years) and of isiXhosa ancestry were randomised into a 12-week aerobic and resistance exercise training group (n = 23) and a no exercise group (control, n = 22). Pre and post-intervention testing included assessment of SI, insulin response to glucose (AIRg), insulin secretion rate (ISR), hepatic insulin extraction (FEL) and disposition index (DI) (AIRg × SI) (frequently sampled i.v. glucose tolerance test); fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat content and abdominal s.c. and visceral adipose tissue volumes (MRI).

Results: Exercise training increased VO2peak (mean ± s.d.: 24.9 ± 2.42 to 27.6 ± 3.39 mL/kg/min, P < 0.001), SI (2.0 (1.2-2.8) to 2.2 (1.5-3.7) (mU/l)-1 min-1, P = 0.005) and DI (median (interquartile range): 6.1 (3.6-7.1) to 6.5 (5.6-9.2) × 103 arbitrary units, P = 0.028), and decreased gynoid fat mass (18.5 ± 1.7 to 18.2 ± 1.6%, P < 0.001) and body weight (84.1 ± 8.7 to 83.3 ± .9.7 kg, P = 0.038). None of these changes were observed in the control group, but body weight increased (P = 0.030). AIRg, ISR and FEL, VAT, SAT and ectopic fat were unaltered after exercise training. The increase in SI and DI were not associated with changes in regional or ectopic fat.

Conclusion: Exercise training increased SI independent from changes in hyperinsulinemia and ectopic fat, suggesting that ectopic fat might not be a principal determinant of insulin resistance in this cohort.

Original language	English
Pages (from-to)	51-61
Number of pages	11
Journal	European Journal of Endocrinology
Volume	183
Issue number	1
DOIs	https://doi.org/10.1530/EJE-19-0957
Publication status	Published - 1 Jul 2020

Keywords

Adipose Tissue/metabolism
Adiposity
Adult
Blood Glucose
Exercise Therapy/methods
Female
Humans
Hyperinsulinism/complications
Insulin Resistance
Obesity/complications
South Africa
Treatment Outcome
Young Adult

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Fortuin-de Smidt, M. C., Mendham, A. E., Hauksson, J., Hakim, O., Stefanovski, D., Clamp, L., Phiri, L., Swart, J., Goff, L. M., Micklesfield, L. K., Kahn, S. E., Olsson, T., & Goedecke, J. H. (2020). Effect of exercise training on insulin sensitivity, hyperinsulinemia and ectopic fat in black South African women: a randomized controlled trial. European Journal of Endocrinology, 183(1), 51-61. https://doi.org/10.1530/EJE-19-0957

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abstract = "Objective: We investigated the effects of a 12-week exercise intervention on insulin sensitivity (SI) and hyperinsulinemia and associated changes in regional and ectopic fat.Research design and methods: Healthy, black South African women with obesity (mean age 23 ± 3.5 years) and of isiXhosa ancestry were randomised into a 12-week aerobic and resistance exercise training group (n = 23) and a no exercise group (control, n = 22). Pre and post-intervention testing included assessment of SI, insulin response to glucose (AIRg), insulin secretion rate (ISR), hepatic insulin extraction (FEL) and disposition index (DI) (AIRg × SI) (frequently sampled i.v. glucose tolerance test); fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat content and abdominal s.c. and visceral adipose tissue volumes (MRI).Results: Exercise training increased VO2peak (mean ± s.d.: 24.9 ± 2.42 to 27.6 ± 3.39 mL/kg/min, P < 0.001), SI (2.0 (1.2-2.8) to 2.2 (1.5-3.7) (mU/l)-1 min-1, P = 0.005) and DI (median (interquartile range): 6.1 (3.6-7.1) to 6.5 (5.6-9.2) × 103 arbitrary units, P = 0.028), and decreased gynoid fat mass (18.5 ± 1.7 to 18.2 ± 1.6%, P < 0.001) and body weight (84.1 ± 8.7 to 83.3 ± .9.7 kg, P = 0.038). None of these changes were observed in the control group, but body weight increased (P = 0.030). AIRg, ISR and FEL, VAT, SAT and ectopic fat were unaltered after exercise training. The increase in SI and DI were not associated with changes in regional or ectopic fat.Conclusion: Exercise training increased SI independent from changes in hyperinsulinemia and ectopic fat, suggesting that ectopic fat might not be a principal determinant of insulin resistance in this cohort.",

keywords = "Adipose Tissue/metabolism, Adiposity, Adult, Blood Glucose, Exercise Therapy/methods, Female, Humans, Hyperinsulinism/complications, Insulin Resistance, Obesity/complications, South Africa, Treatment Outcome, Young Adult",

author = "{Fortuin-de Smidt}, {Melony C} and Mendham, {Amy E} and Jon Hauksson and Olah Hakim and Darko Stefanovski and Louise Clamp and Lindokuhle Phiri and Jeroen Swart and Goff, {Louise M} and Micklesfield, {Lisa K} and Kahn, {Steven E} and Tommy Olsson and Goedecke, {Julia H}",

year = "2020",

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doi = "10.1530/EJE-19-0957",

language = "English",

volume = "183",

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Fortuin-de Smidt, MC, Mendham, AE, Hauksson, J, Hakim, O, Stefanovski, D, Clamp, L, Phiri, L, Swart, J, Goff, LM, Micklesfield, LK, Kahn, SE, Olsson, T & Goedecke, JH 2020, 'Effect of exercise training on insulin sensitivity, hyperinsulinemia and ectopic fat in black South African women: a randomized controlled trial', European Journal of Endocrinology, vol. 183, no. 1, pp. 51-61. https://doi.org/10.1530/EJE-19-0957

TY - JOUR

T1 - Effect of exercise training on insulin sensitivity, hyperinsulinemia and ectopic fat in black South African women

T2 - a randomized controlled trial

AU - Fortuin-de Smidt, Melony C

AU - Mendham, Amy E

AU - Hauksson, Jon

AU - Hakim, Olah

AU - Stefanovski, Darko

AU - Clamp, Louise

AU - Phiri, Lindokuhle

AU - Swart, Jeroen

AU - Goff, Louise M

AU - Micklesfield, Lisa K

AU - Kahn, Steven E

AU - Olsson, Tommy

AU - Goedecke, Julia H

PY - 2020/7/1

Y1 - 2020/7/1

N2 - Objective: We investigated the effects of a 12-week exercise intervention on insulin sensitivity (SI) and hyperinsulinemia and associated changes in regional and ectopic fat.Research design and methods: Healthy, black South African women with obesity (mean age 23 ± 3.5 years) and of isiXhosa ancestry were randomised into a 12-week aerobic and resistance exercise training group (n = 23) and a no exercise group (control, n = 22). Pre and post-intervention testing included assessment of SI, insulin response to glucose (AIRg), insulin secretion rate (ISR), hepatic insulin extraction (FEL) and disposition index (DI) (AIRg × SI) (frequently sampled i.v. glucose tolerance test); fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat content and abdominal s.c. and visceral adipose tissue volumes (MRI).Results: Exercise training increased VO2peak (mean ± s.d.: 24.9 ± 2.42 to 27.6 ± 3.39 mL/kg/min, P < 0.001), SI (2.0 (1.2-2.8) to 2.2 (1.5-3.7) (mU/l)-1 min-1, P = 0.005) and DI (median (interquartile range): 6.1 (3.6-7.1) to 6.5 (5.6-9.2) × 103 arbitrary units, P = 0.028), and decreased gynoid fat mass (18.5 ± 1.7 to 18.2 ± 1.6%, P < 0.001) and body weight (84.1 ± 8.7 to 83.3 ± .9.7 kg, P = 0.038). None of these changes were observed in the control group, but body weight increased (P = 0.030). AIRg, ISR and FEL, VAT, SAT and ectopic fat were unaltered after exercise training. The increase in SI and DI were not associated with changes in regional or ectopic fat.Conclusion: Exercise training increased SI independent from changes in hyperinsulinemia and ectopic fat, suggesting that ectopic fat might not be a principal determinant of insulin resistance in this cohort.

AB - Objective: We investigated the effects of a 12-week exercise intervention on insulin sensitivity (SI) and hyperinsulinemia and associated changes in regional and ectopic fat.Research design and methods: Healthy, black South African women with obesity (mean age 23 ± 3.5 years) and of isiXhosa ancestry were randomised into a 12-week aerobic and resistance exercise training group (n = 23) and a no exercise group (control, n = 22). Pre and post-intervention testing included assessment of SI, insulin response to glucose (AIRg), insulin secretion rate (ISR), hepatic insulin extraction (FEL) and disposition index (DI) (AIRg × SI) (frequently sampled i.v. glucose tolerance test); fat mass and regional adiposity (dual-energy X-ray absorptiometry); hepatic, pancreatic and skeletal muscle fat content and abdominal s.c. and visceral adipose tissue volumes (MRI).Results: Exercise training increased VO2peak (mean ± s.d.: 24.9 ± 2.42 to 27.6 ± 3.39 mL/kg/min, P < 0.001), SI (2.0 (1.2-2.8) to 2.2 (1.5-3.7) (mU/l)-1 min-1, P = 0.005) and DI (median (interquartile range): 6.1 (3.6-7.1) to 6.5 (5.6-9.2) × 103 arbitrary units, P = 0.028), and decreased gynoid fat mass (18.5 ± 1.7 to 18.2 ± 1.6%, P < 0.001) and body weight (84.1 ± 8.7 to 83.3 ± .9.7 kg, P = 0.038). None of these changes were observed in the control group, but body weight increased (P = 0.030). AIRg, ISR and FEL, VAT, SAT and ectopic fat were unaltered after exercise training. The increase in SI and DI were not associated with changes in regional or ectopic fat.Conclusion: Exercise training increased SI independent from changes in hyperinsulinemia and ectopic fat, suggesting that ectopic fat might not be a principal determinant of insulin resistance in this cohort.

KW - Adipose Tissue/metabolism

KW - Adiposity

KW - Adult

KW - Blood Glucose

KW - Exercise Therapy/methods

KW - Female

KW - Humans

KW - Hyperinsulinism/complications

KW - Insulin Resistance

KW - Obesity/complications

KW - South Africa

KW - Treatment Outcome

KW - Young Adult

U2 - 10.1530/EJE-19-0957

DO - 10.1530/EJE-19-0957

M3 - Article

C2 - 32503004

SN - 0804-4643

VL - 183

SP - 51

EP - 61

JO - European Journal of Endocrinology

JF - European Journal of Endocrinology

IS - 1

ER -