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Malaikah S, Willis SA, Henson J, Sargeant JA, Yates T, Thackray AE, Goltz FR, Roberts MJ, Bodicoat DH, Aithal GP, Stensel DJ, King JA. Associations of objectively measured physical activity, sedentary time and cardiorespiratory fitness with adipose tissue insulin resistance and ectopic fat. Int J Obes (Lond) 2023; 47:1000-1007. [PMID: 37491534 PMCID: PMC10511317 DOI: 10.1038/s41366-023-01350-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 06/29/2023] [Accepted: 07/14/2023] [Indexed: 07/27/2023]
Abstract
BACKGROUND/OBJECTIVES Inadequate movement, excess adiposity, and insulin resistance augment cardiometabolic risk. This study examined the associations of objectively measured moderate-to-vigorous intensity physical activity (MVPA), sedentary time and cardiorespiratory fitness (CRF), with adipose tissue insulin resistance and ectopic fat. METHODS Data were combined from two previous experimental studies with community volunteers (n = 141, male = 60%, median (interquartile range) age = 37 (19) years, body mass index (BMI) = 26.1 (6.3) kg·m-2). Adipose tissue insulin resistance was assessed using the adipose tissue insulin resistance index (Adipo-IR); whilst magnetic resonance imaging (MRI) was used to measure liver, visceral (VAT) and subcutaneous abdominal adipose tissue (ScAT). Sedentary time and MVPA were measured via an ActiGraph GT3X+ accelerometer. Generalized linear models examined the association of CRF, MVPA, and sedentary time with Adipo-IR and fat depots. Interaction terms explored the moderating influence of age, sex, BMI and CRF. RESULTS After controlling for BMI and cardiometabolic variables, sedentary time was positively associated with Adipo-IR (β = 0.68 AU [95%CI = 0.27 to 1.10], P < 0.001). The association between sedentary time and Adipo-IR was moderated by age, CRF and BMI; such that it was stronger in individuals who were older, had lower CRF and had a higher BMI. Sedentary time was also positively associated with VAT (β = 0.05 L [95%CI = 0.01 to 0.08], P = 0.005) with the relationship being stronger in females than males. CRF was inversely associated with VAT (β = -0.02 L [95%CI = -0.04 to -0.01], P = 0.003) and ScAT (β = -0.10 L [95%CI = -0.13 to -0.06], P < 0.001); with sex and BMI moderating the strength of associations with VAT and ScAT, respectively. CONCLUSIONS Sedentary time is positively associated with adipose tissue insulin resistance which regulates lipogenesis and lipolysis. CRF is independently related to central fat storage which is a key risk factor for cardiometabolic disease.
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Affiliation(s)
- Sundus Malaikah
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
- Clinical Nutrition Department, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Scott A Willis
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
| | - Joseph Henson
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
- Diabetes Research Centre, University of Leicester, Leicester, UK
| | - Jack A Sargeant
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
- Diabetes Research Centre, University of Leicester, Leicester, UK
| | - Thomas Yates
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
- Diabetes Research Centre, University of Leicester, Leicester, UK
| | - Alice E Thackray
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
| | - Fernanda R Goltz
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
| | - Matthew J Roberts
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
| | | | - Guruprasad P Aithal
- Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK
| | - David J Stensel
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan
- Department of Sport Science and Physical Education, The Chinese University of Hong Kong, Central Ave, Hong Kong
| | - James A King
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK.
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Meister BM, Hong SG, Shin J, Rath M, Sayoc J, Park JY. Healthy versus Unhealthy Adipose Tissue Expansion: the Role of Exercise. J Obes Metab Syndr 2022; 31:37-50. [PMID: 35283364 PMCID: PMC8987461 DOI: 10.7570/jomes21096] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 12/14/2022] Open
Abstract
Although the hallmark of obesity is the expansion of adipose tissue, not all adipose tissue expansion is the same. Expansion of healthy adipose tissue is accompanied by adequate capillary angiogenesis and mitochondria-centered metabolic integrity, whereas expansion of unhealthy adipose tissue is associated with capillary and mitochondrial derangement, resulting in deposition of immune cells (M1-stage macrophages) and excess production of pro-inflammatory cytokines. Accumulation of these dysfunctional adipose tissues has been linked to the development of obesity comorbidities, such as type 2 diabetes, hypertension, dyslipidemia, and cardiovascular disease, which are leading causes of human mortality and morbidity in modern society. Mechanistically, vascular rarefaction and mitochondrial incompetency (for example, low mitochondrial content, fragmented mitochondria, defective mitochondrial respiratory function, and excess production of mitochondrial reactive oxygen species) are frequently observed in adipose tissue of obese patients. Recent studies have demonstrated that exercise is a potent behavioral intervention for preventing and reducing obesity and other metabolic diseases. However, our understanding of potential cellular mechanisms of exercise, which promote healthy adipose tissue expansion, is at the beginning stage. In this review, we hypothesize that exercise can induce unique physiological stimuli that can alter angiogenesis and mitochondrial remodeling in adipose tissues and ultimately promote the development and progression of healthy adipogenesis. We summarize recent reports on how regular exercise can impose differential processes that lead to the formation of either healthy or unhealthy adipose tissue and discuss key knowledge gaps that warrant future research.
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Affiliation(s)
- Benjamin M Meister
- Department of Kinesiology, College of Public Health and Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Soon-Gook Hong
- Department of Kinesiology, College of Public Health and Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Junchul Shin
- Department of Kinesiology, College of Public Health and Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Meghan Rath
- Department of Kinesiology, College of Public Health and Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Jacqueline Sayoc
- Department of Kinesiology, College of Public Health and Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Joon-Young Park
- Department of Kinesiology, College of Public Health and Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
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Hu D, Russell RD, Remash D, Greenaway T, Rattigan S, Squibb KA, Jones G, Ross RM, Roberts CK, Premilovac D, Richards SM, Keske MA. Are the metabolic benefits of resistance training in type 2 diabetes linked to improvements in adipose tissue microvascular blood flow? Am J Physiol Endocrinol Metab 2018; 315:E1242-E1250. [PMID: 30351988 DOI: 10.1152/ajpendo.00234.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The microcirculation in adipose tissue is markedly impaired in type 2 diabetes (T2D). Resistance training (RT) often increases muscle mass and promotes a favorable metabolic profile in people with T2D, even in the absence of fat loss. Whether the metabolic benefits of RT in T2D are linked to improvements in adipose tissue microvascular blood flow is unknown. Eighteen sedentary people with T2D (7 women/11 men, 52 ± 7 yr) completed 6 wk of RT. Before and after RT, overnight-fasted participants had blood sampled for clinical chemistries (glucose, insulin, lipids, HbA1c, and proinflammatory markers) and underwent an oral glucose challenge (OGC; 50 g glucose × 2 h) and a DEXA scan to assess body composition. Adipose tissue microvascular blood volume and flow were assessed at rest and 1 h post-OGC using contrast-enhanced ultrasound. RT significantly reduced fasting blood glucose ( P = 0.006), HbA1c ( P = 0.007), 2-h glucose area under the time curve post-OGC ( P = 0.014), and homeostatic model assessment of insulin resistance ( P = 0.005). This was accompanied by a small reduction in total body fat ( P = 0.002), trunk fat ( P = 0.023), and fasting triglyceride levels ( P = 0.029). Lean mass ( P = 0.003), circulating TNF-α ( P = 0.006), and soluble VCAM-1 ( P < 0.001) increased post-RT. There were no significant changes in adipose tissue microvascular blood volume or flow following RT; however those who did have a higher baseline microvascular blood flow post-RT also had lower fasting triglyceride levels ( r = -0.476, P = 0.045). The anthropometric, glycemic, and insulin-sensitizing benefits of 6 wk of RT in people with T2D are not associated with an improvement in adipose tissue microvascular responses; however, there may be an adipose tissue microvascular-linked benefit to fasting triglyceride levels.
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Affiliation(s)
- Donghua Hu
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- Department of Pharmacology, Anhui Medical University , Hefei , China
| | - Ryan D Russell
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- Department of Health and Human Performance, College of Health Services, University of Texas Rio Grande Valley , Brownsville, Texas
| | - Devika Remash
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
| | - Timothy Greenaway
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
- Royal Hobart Hospital , Hobart, Tasmania , Australia
| | - Stephen Rattigan
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
| | - Kathryn A Squibb
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
| | - Graeme Jones
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
| | - Renee M Ross
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
| | - Christian K Roberts
- Geriatric Research, Education and Clinical Center, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California
| | - Dino Premilovac
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
| | - Stephen M Richards
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- School of Medicine, University of Tasmania , Hobart, Tasmania , Australia
| | - Michelle A Keske
- Menzies Institute for Medical Research, University of Tasmania , Hobart, Tasmania , Australia
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University , Geelong , Australia
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Yan H, Pierce JR, Myers KB, Dubose KD, Dubis GS, Tanner CJ, Hickner RC. Exercise Effects on Adipose Tissue Postprandial Lipolysis and Blood Flow in Children. Med Sci Sports Exerc 2018; 50:1249-1257. [PMID: 29381651 DOI: 10.1249/mss.0000000000001566] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Poor suppression of lipolysis and blunted increase in blood flow after meal ingestion in obese adults may indicate resistance to the antilipolytic action of insulin. Exercise may be used to normalize lipolytic responses to food intake by increasing insulin sensitivity. PURPOSE To determine if acute bouts of aerobic exercise and/or excise training alter lipolytic and blood flow responses to food intake in lean (LN) and obese (OB) children. METHODS Sixty-five children (9-11 yr) were randomized into acute exercise (EX: 16 LN and 28 OB) or control (CON: 9 LN and 12 OB) groups that exercised (EX), or rested (CON) between standardized breakfast and lunch. Microdialysis probes were inserted into the subcutaneous abdominal adipose tissue to monitor interstitial glycerol (lipolysis) and blood flow. Changes in interstitial glycerol and nutritive flow were calculated from dialysate samples before and after each meal. A subgroup (OB = 15 and LN = 9) from the acute exercise group underwent 16 wk of aerobic exercise training. RESULTS Poor suppression of lipolysis and a blunted increase in adipose tissue nutritive blood flow in response to breakfast was associated with BMI percentile (r = 0.3, P < 0.05). These responses were normalized at lunch in the OB in the EX (P < 0.05), but not in OB in the CON. Sixteen weeks of exercise training did not improve meal-induced blood flow and marginally altered the antilipolytic response to the two meals (P = 0.06). CONCLUSIONS Daily bouts of acute aerobic exercise should be used to improve the antilipolytic and nutritive blood flow response to a subsequent meal in obese children.
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Affiliation(s)
- Huimin Yan
- Human Performance Laboratory, East Carolina University, Greenville, NC.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC.,Center for Health Disparities, East Carolina University, Greenville, NC.,Department of Kinesiology, East Carolina University, Greenville, NC.,Department of Exercise and Health Sciences, University of Massachusetts Boston, Boston, MA
| | - Joseph R Pierce
- Human Performance Laboratory, East Carolina University, Greenville, NC.,Department of Kinesiology, East Carolina University, Greenville, NC
| | - Kimberly B Myers
- Department of Nutrition Science, East Carolina University, Greenville, NC
| | - Katrina D Dubose
- Department of Kinesiology, East Carolina University, Greenville, NC
| | - Gabriel S Dubis
- Human Performance Laboratory, East Carolina University, Greenville, NC.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC.,Department of Kinesiology, East Carolina University, Greenville, NC
| | - Charles J Tanner
- Human Performance Laboratory, East Carolina University, Greenville, NC.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC.,Department of Kinesiology, East Carolina University, Greenville, NC
| | - Robert C Hickner
- Human Performance Laboratory, East Carolina University, Greenville, NC.,East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC.,Center for Health Disparities, East Carolina University, Greenville, NC.,Department of Kinesiology, East Carolina University, Greenville, NC.,Department of Physiology, East Carolina University, Greenville, NC.,Discipline of Biokinetics, Exercise, and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Westville, SOUTH AFRICA.,Department of Nutrition, Food and Exercise Sciences, College of Human Sciences, Florida State University, Tallahassee, FL
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Brouwers B, Hesselink MKC, Schrauwen P, Schrauwen-Hinderling VB. Effects of exercise training on intrahepatic lipid content in humans. Diabetologia 2016; 59:2068-79. [PMID: 27393135 PMCID: PMC5016557 DOI: 10.1007/s00125-016-4037-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 06/08/2016] [Indexed: 02/07/2023]
Abstract
Non-alcoholic fatty liver (NAFL) is the most common liver disorder in western society. Various factors may play a role in determining hepatic fat content, such as delivery of lipids to the liver, de novo lipogenesis, hepatic lipid oxidation, secretion of intrahepatic lipids to the circulation or a combination of these. If delivery of lipids to the liver outweighs the sum of hepatic lipid oxidation and secretion, the intrahepatic lipid (IHL) content starts to increase and NAFL may develop. NAFL is closely related to obesity and insulin resistance and a fatty liver increases the vulnerability to type 2 diabetes development. Exercise training is a cornerstone in the treatment and prevention of type 2 diabetes. There is a large body of literature describing the beneficial metabolic consequences of exercise training on skeletal muscle metabolism. Recent studies have started to investigate the effects of exercise training on liver metabolism but data is still limited. Here, first, we briefly discuss the routes by which IHL content is modulated. Second, we review whether and how these contributing routes might be modulated by long-term exercise training. Third, we focus on the effects of acute exercise on IHL metabolism, since exercise also might affect hepatic metabolism in the physically active state. This will give insight into whether the effect of exercise training on IHL could be explained by the accumulated effect of acute bouts of exercise, or whether adaptations might occur only after long-term exercise training. The primary focus of this review will be on observations made in humans. Where human data is missing, data obtained from well-accepted animal models will be used.
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Affiliation(s)
- Bram Brouwers
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center +, Maastricht, the Netherlands
- Department of Human Biology and Human Movement Sciences, Maastricht University Medical Center +, Maastricht, the Netherlands
| | - Matthijs K C Hesselink
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center +, Maastricht, the Netherlands
- Department of Human Biology and Human Movement Sciences, Maastricht University Medical Center +, Maastricht, the Netherlands
| | - Patrick Schrauwen
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center +, Maastricht, the Netherlands
- Department of Human Biology and Human Movement Sciences, Maastricht University Medical Center +, Maastricht, the Netherlands
| | - Vera B Schrauwen-Hinderling
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center +, Maastricht, the Netherlands.
- Department of Human Biology and Human Movement Sciences, Maastricht University Medical Center +, Maastricht, the Netherlands.
- Department of Radiology, Maastricht University Medical Center +, P.O. Box 616, 6200 MD, Maastricht, the Netherlands.
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Thompson D, Karpe F, Lafontan M, Frayn K. Physical activity and exercise in the regulation of human adipose tissue physiology. Physiol Rev 2012; 92:157-91. [PMID: 22298655 DOI: 10.1152/physrev.00012.2011] [Citation(s) in RCA: 216] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Physical activity and exercise are key components of energy expenditure and therefore of energy balance. Changes in energy balance alter fat mass. It is therefore reasonable to ask: What are the links between physical activity and adipose tissue function? There are many complexities. Physical activity is a multifaceted behavior of which exercise is just one component. Physical activity influences adipose tissue both acutely and in the longer term. A single bout of exercise stimulates adipose tissue blood flow and fat mobilization, resulting in delivery of fatty acids to skeletal muscles at a rate well-matched to metabolic requirements, except perhaps in vigorous intensity exercise. The stimuli include adrenergic and other circulating factors. There is a period following an exercise bout when fatty acids are directed away from adipose tissue to other tissues such as skeletal muscle, reducing dietary fat storage in adipose. With chronic exercise (training), there are changes in adipose tissue physiology, particularly an enhanced fat mobilization during acute exercise. It is difficult, however, to distinguish chronic "structural" changes from those associated with the last exercise bout. In addition, it is difficult to distinguish between the effects of training per se and negative energy balance. Epidemiological observations support the idea that physically active people have relatively low fat mass, and intervention studies tend to show that exercise training reduces fat mass. A much-discussed effect of exercise versus calorie restriction in preferentially reducing visceral fat is not borne out by meta-analyses. We conclude that, in addition to the regulation of fat mass, physical activity may contribute to metabolic health through beneficial dynamic changes within adipose tissue in response to each activity bout.
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Can alternating lower body negative and positive pressure during exercise alter regional body fat distribution or skin appearance? Eur J Appl Physiol 2011; 112:1861-71. [DOI: 10.1007/s00421-011-2147-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 08/03/2011] [Indexed: 10/17/2022]
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Münzer T, Harman SM, Sorkin JD, Blackman MR. Growth hormone and sex steroid effects on serum glucose, insulin, and lipid concentrations in healthy older women and men. J Clin Endocrinol Metab 2009; 94:3833-41. [PMID: 19602554 PMCID: PMC2758730 DOI: 10.1210/jc.2009-1275] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
CONTEXT With aging, GH, IGF-I, and sex steroid concentrations and glucose tolerance decrease, and body fat and serum lipids increase. OBJECTIVE The aim of the study was to assess GH and/or sex steroid administration effects on serum glucose, insulin, insulin sensitivity, and lipids in older individuals. DESIGN A double-masked, 2 x 2 factorial, placebo-controlled, double-dummy design was used for the study. INTERVENTION GH and/or sex steroid [transdermal estradiol plus oral medroxyprogesterone acetate in women (HRT); testosterone enanthate (T) in men] were administered for 6 months. PARTICIPANTS Healthy, community-dwelling women (n = 57) and men (n = 74) ages 65-88 yr (mean, 72 yr) participated in the study. MAIN OUTCOME MEASURES We measured serum glucose, insulin, and insulin sensitivity [quantitative insulin sensitivity check index (QUICKI) and insulin sensitivity index (ISI)] before and during an oral glucose tolerance test and lipid profiles. RESULTS In women, GH did not alter oral glucose tolerance test 120 min or 2-h area under the curve (AUC) glucose values, but it increased 120 min insulin and AUC insulin. There were no significant effects of HRT or GH+HRT. ISI and QUICKI decreased after GH. In men, GH increased 120 min and AUC glucose and insulin AUC. GH+T increased 120 min glucose and glucose and insulin AUCs. T alone did not affect glucose or insulin. ISI decreased after GH and GH+T, whereas QUICKI decreased after GH. GH in women and men and GH+T in men decreased QUICKI by 4 wk. In women, HRT decreased total cholesterol and low-density lipoprotein (LDL)-cholesterol, and GH decreased LDL-cholesterol. In men, total cholesterol decreased after T and GH+T. LDL-cholesterol decreased after GH and GH+T. GH increased serum triglycerides. CONCLUSIONS GH administration to healthy older individuals for 6 months increased insulin resistance with moderately beneficial effects on lipids.
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Affiliation(s)
- Thomas Münzer
- Endocrine Section, Laboratory of Clinical Investigation, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA
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Hansen M, Morthorst R, Larsson B, Flyvbjerg A, Rasmussen MH, Orskov H, Astrup A, Kjaer M, Lange KHW. Effects of 2 wk of GH administration on 24-h indirect calorimetry in young, healthy, lean men. Am J Physiol Endocrinol Metab 2005; 289:E1030-8. [PMID: 16046455 DOI: 10.1152/ajpendo.00124.2005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed as a randomized, double-blind placebo (Plc)-controlled study to determine the effect of 2 wk of growth hormone administration (GH-adm.) on energy expenditure (EE) and substrate oxidation in healthy humans. Sixteen young healthy men were divided into two groups. The study consisted of two 24-h measurements (indirect calorimetry), separated by 2 wk of either Plc or GH injections (6 IU/day). At baseline, no significant differences were observed between the two groups in any of the measured anthropometric, hormonal, or metabolic parameters, neither did the parameters change over time in the Plc group. GH-adm. resulted in a 4.4% increase in 24-h EE (P < 0.05) and an increase in fat oxidation by 29% (P < 0.05). However, a decrease in the respiratory quotient was only observed in the postabsorptive phase after an overnight fast (0.84 +/- 0.1 to 0.79 +/- 0.1, P < 0.05). Furthermore, lean body mass (LBM) was increased by GH-adm. only [62.8 +/- 2.5 kg (baseline) vs. 64.7 +/- 2.4 kg (after), P < 0.001]. In conclusion, GH-adm. increases 24-h EE, which may be partly explained by increased LBM. Furthermore, GH-adm. stimulates fat combustion, especially in the postabsorptive state.
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Affiliation(s)
- Mette Hansen
- Institute of Sports Medicine, Copenhagen, Building 8, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark.
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Abstract
Interventions aimed at increasing fat metabolism could potentially reduce the symptoms of metabolic diseases such as obesity and type 2 diabetes and may have tremendous clinical relevance. Hence, an understanding of the factors that increase or decrease fat oxidation is important. Exercise intensity and duration are important determinants of fat oxidation. Fat oxidation rates increase from low to moderate intensities and then decrease when the intensity becomes high. Maximal rates of fat oxidation have been shown to be reached at intensities between 59% and 64% of maximum oxygen consumption in trained individuals and between 47% and 52% of maximum oxygen consumption in a large sample of the general population. The mode of exercise can also affect fat oxidation, with fat oxidation being higher during running than cycling. Endurance training induces a multitude of adaptations that result in increased fat oxidation. The duration and intensity of exercise training required to induce changes in fat oxidation is currently unknown. Ingestion of carbohydrate in the hours before or on commencement of exercise reduces the rate of fat oxidation significantly compared with fasted conditions, whereas fasting longer than 6 h optimizes fat oxidation. Fat oxidation rates have been shown to decrease after ingestion of high-fat diets, partly as a result of decreased glycogen stores and partly because of adaptations at the muscle level.
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Affiliation(s)
- Juul Achten
- School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
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Lange KHW. Fat metabolism in exercise - with special reference to training and growth hormone administration. Scand J Med Sci Sports 2004; 14:74-99. [PMID: 15043630 DOI: 10.1111/j.1600-0838.2004.381.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Despite abundance of fat, exclusive dependency on fat oxidation can only sustain a metabolic rate corresponding to 50-60% of VO(2max) in humans. This puzzling finding has been subject to intense research for many years. Lately, it has gained renewed interest as a consequence of increased obesity and physical inactivity imposed by Western lifestyle. Why are humans so poor at metabolizing fat? Can fat metabolism be manipulated by exercise, training, diet and hormones? And why is fat stored in specialized adipose tissue and not just as lipid droplets inside muscle cells? In the present review, human fat metabolism is discussed in relation to how human fat metabolism is designed. Limitations in this design are explored and examples of different designs for fat metabolism from animal physiology are included to illustrate these limitations. Various means of manipulating fat metabolism are discussed with special emphasis on exercise, training, growth hormone (GH) physiology and GH administration. It is concluded that fat stores, non-esterified fatty acids (NEFAs) availability and enzymes for fat oxidation can be increased substantially. However, it is almost impossible to increase fat oxidation during endurance exercise at higher intensities. It seems that, for some reason, the human being is far from optimally designed for fat oxidation during exercise. Acute GH administration has several unexpected effects on fat and carbohydrate metabolism during aerobic exercise, and future research in this area is likely to provide valuable information with respect to GH physiology and the regulation of fat and carbohydrate metabolism during aerobic exercise.
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Lange KHW, Larsson B, Flyvbjerg A, Dall R, Bennekou M, Rasmussen MH, Ørskov H, Kjaer M. Acute growth hormone administration causes exaggerated increases in plasma lactate and glycerol during moderate to high intensity bicycling in trained young men. J Clin Endocrinol Metab 2002; 87:4966-75. [PMID: 12414860 DOI: 10.1210/jc.2001-011797] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We studied the acute effects of a single, sc GH dose on exercise performance and metabolism during bicycling. Seven highly trained men [age, 26 +/- 1 yr (mean +/- SEM); weight, 77 +/- 3 kg; maximal oxygen uptake, 65 +/- 1 ml O(2).min(-1).kg(-1)] performed 90 min of bicycling 4 h after receiving 7.5 IU (2.5 mg) GH or placebo in a randomized, double-blinded, cross-over design trial. A standardized pre-exercise meal was given 2 h before exercise. Blood was sampled at rest and during exercise and analyzed for GH, IGF-I, glucose, lactate, insulin, glycerol, and nonesterified fatty acids (NEFA). In the placebo trial, all subjects completed the exercise protocol without any difficulties. In contrast, two subjects were not able to complete the exercise protocol in the GH trial, and one subject barely managed to complete the protocol. In addition, GH administration resulted in exaggerated increases in plasma lactate concentrations during exercise (P < 0.0001). The combined lipolytic effect of GH and exercise, evidenced by increased plasma glycerol and serum NEFA concentrations, was 3-fold greater than the effect of exercise alone (P < 0.0001), but this increased substrate availability did not result in increased whole body fat oxidation (indirect calorimetry). Plasma glucose was, on average, 9% higher during exercise after GH administration compared with placebo (P < 0.0001). We conclude that a single, relevant GH dose causes exaggerated increases in plasma lactate and glycerol as well as serum NEFA during 90 min of subsequent bicycling at moderate to high intensity. The exaggerated increase in plasma lactate may be associated with substantially decreased exercise performance.
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Affiliation(s)
- Kai Henrik Wiborg Lange
- Sports Medicine Research Unit, Building 8, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV, Denmark.
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