Adipose tissue and brain metabolic adaptations to sprint interval training and moder-ate-intensity continuous training; studies in healthy and insulin resistant subjects.

Abstract: Background: Insulin resistance (IR) is associated with metabolic disturbances in several tissues, including increased insulin-stimulated glucose uptake in brain, decreased glucose uptake in adipose tissue and accumulation of fat in and around the myocardium. Whether these disturbances can be normalized by exercise is still uninvestigated. Thus, the aims of this study were to determine the myocardial adiposity in and around myocardium, to elucidate exercise training-induced metabolic adaptations in brain and adipose tissue and to compare the training responses between, sprint interval training (SIT) vs. moderate-intensity continuous training (MICT) in subjects with IR. Methods: Middle-aged, sedentary healthy subjects (n=28) and subjects with IR (n=26) were andomized into SIT and MICT interventions for two weeks. Brain and adipose tissue metabolism in terms of glucose uptake and free fatty acid uptake and myocardial adiposity were determined non-invasively using positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Results: Two-week of exercise training, both SIT and MICT, decreased epi- and pericardial fat volumes and adipose tissue glucose and fatty acid metabolism similarly in healthy subjects and subjects with IR despite the baseline differences. In short-term, only SIT showed improvements in aerobic capacity, visceral adipose tissue glucose uptake and a decrease in insulin-stimulated brain glucose uptake in IR subjects. Conclusions: Exercise training has beneficial effects on adipose tissue volume and metabolism despite the baseline glucose tolerance. This study also showed for the first time, that exercise training can decrease insulin-stimulated brain glucose uptake. These findings further support the therapeutic potential of exercise training in subjects with IR.Tiivistelmä: Tausta: Insuliiniresistanssin on havaittu olevan yhteydessä aineenvaihdunnan häiriöihin useissa kudoksissa. Näitä häiriöitä ovat muun muassa aivojen lisääntynyt glukoosinotto, rasvakudoksen alentunut insuliiniherkkyys sekä rasvan kertyminen sydänlihaksen sisään ja ympärille. Vielä on monilta osin tuntematta, voidaanko näitä muutoksi normalisoida liikuntaharjoittelun avulla. Täten, tämän tutkimuksen tarkoituksena oli selvittää kahden intensiteetiltään eroavan liikuntaharjoittelumenetelmän vaikutuksia aivojen ja eri rasvakudosten rasva- ja sokeriaineenvaihdunnassa terveillä ja insuliiniresistenteillä henkilöillä. Menetelmät: Tutkimukseen osallistuneet keski-ikäiset, inaktiiviset terveet miehet (n=28) sekä tyypin 2 diabetesta sairastavat naiset ja miehet (n=26) satunnaistettiin kohtalaiskuormitteiseen (MICT) tai korkeatehoiseen itervalliharjoitteluryhmään (SIT) kahden viikon ajaksi. Aivojen ja rasvakudoksen sokeri- ja rasvahappoaineenvaihduntaa sekä sydänlihaksen rasvoittumista tutkittiin positroniemissiotomografialla (PET), tietokonetomografialla (TT), magneettiresonassikuvantamisella (MRI) sekä magneettiresonanssispektroskopialla (MRS). Tulokset: Kahden viikon liikuntaharjoittelu, sekä SIT että MICT, alensi sydäntä ympäröivien epi- ja perikardiaali rasvamassojen määrää sekä paransi rasvakudoksen glukoosi- ja rasvahappoaineenvaihduntaa ilman eroja terveiden ja insuliiniresistenttien välillä huolimatta erosta lähtötasossa. Ainoastaan SIT harjoittelu paransi kestävyyskuntoa, viskeraalirasvan insuliiniherkkyyttä sekä alensi aivojen insuliini-stimuloitua glukoosinottoa insuliiniresistenteillä henkilöillä. Johtopäätökset: Liikuntaharjoittelulla on suotuisia vaikutuksia rasvakudosten määrään sekä aineenvaihduntaan insuliiniherkkyyden lähtötasosta riippumatta. Tutkimuksessa osoitetiin myös ensimmäistä kertaa, että liikuntaharjoittelu alentaa aivojen sokeriaineenvaihduntaa. Nämä löydökset vahvistavat liikuntaharjoittelun terapeuttista potentiaalia henkilöillä, joilla on insuliiniresistenssi

Exercise training improves adipose tissue metabolism and vasculature regardless of baseline glucose tolerance and sex

Introduction We investigated the effects of a supervised progressive sprint interval training (SIT) and moderate-intensity continuous training (MICT) on adipocyte morphology and adipose tissue metabolism and function; we also tested whether the responses were similar regardless of baseline glucose tolerance and sex. Research design and methods 26 insulin-resistant (IR) and 28 healthy participants were randomized into 2-week-long SIT (4-6x30 s at maximum effort) and MICT (40-60 min at 60% of maximal aerobic capacity (VO2peak)). Insulin-stimulated glucose uptake and fasting-free fatty acid uptake in visceral adipose tissue (VAT), abdominal and femoral subcutaneous adipose tissues (SATs) were quantified with positron emission tomography. Abdominal SAT biopsies were collected to determine adipocyte morphology, gene expression markers of lipolysis, glucose and lipid metabolism and inflammation. Results Training increased glucose uptake in VAT (pPeer reviewe

Systemic cross-talk between brain, gut, and peripheral tissues in glucose homeostasis : effects of exercise training (CROSSYS). Exercise training intervention in monozygotic twins discordant for body weight

Background: Obesity and physical inactivity are major global public health concerns, both of which increase the risk of insulin resistance and type 2 diabetes. Regulation of glucose homeostasis involves cross-talk between the central nervous system, peripheral tissues, and gut microbiota, and is affected by genetics. Systemic cross-talk between brain, gut, and peripheral tissues in glucose homeostasis: effects of exercise training (CROSSYS) aims to gain new systems-level understanding of the central metabolism in human body, and how exercise training affects this cross-talk. Methods: CROSSYS is an exercise training intervention, in which participants are monozygotic twins from pairs discordant for body mass index (BMI) and within a pair at least the other is overweight. Twins are recruited from three population-based longitudinal Finnish twin studies, including twins born in 1983-1987, 1975-1979, and 1945-1958. The participants undergo 6-month-long exercise intervention period, exercising four times a week (including endurance, strength, and high-intensity training). Before and after the exercise intervention, comprehensive measurements are performed in Turku PET Centre, Turku, Finland. The measurements include: two positron emission tomography studies (insulin-stimulated whole-body and tissue-specific glucose uptake and neuroinflammation), magnetic resonance imaging (brain morphology and function, quantification of body fat masses and organ volumes), magnetic resonance spectroscopy (quantification of fat within heart, pancreas, liver and tibialis anterior muscle), echocardiography, skeletal muscle and adipose tissue biopsies, a neuropsychological test battery as well as biosamples from blood, urine and stool. The participants also perform a maximal exercise capacity test and tests of muscular strength. Discussion: This study addresses the major public health problems related to modern lifestyle, obesity, and physical inactivity. An eminent strength of this project is the possibility to study monozygotic twin pairs that share the genome at the sequence level but are discordant for BMI that is a risk factor for metabolic impairments such as insulin resistance. Thus, this exercise training intervention elucidates the effects of obesity on metabolism and whether regular exercise training is able to reverse obesity-related impairments in metabolism in the absence of the confounding effects of genetic factors.Peer reviewe

Exercise training improves adipose tissue metabolism and vasculature regardless of baseline glucose tolerance and sex

Introduction We investigated the effects of a supervised progressive sprint interval training (SIT) and moderate-intensity continuous training (MICT) on adipocyte morphology and adipose tissue metabolism and function; we also tested whether the responses were similar regardless of baseline glucose tolerance and sex.Research design and methods 26 insulin-resistant (IR) and 28 healthy participants were randomized into 2-week-long SIT (4-6x30 s at maximum effort) and MICT (40-60 min at 60% of maximal aerobic capacity (VO2peak)). Insulin-stimulated glucose uptake and fasting-free fatty acid uptake in visceral adipose tissue (VAT), abdominal and femoral subcutaneous adipose tissues (SATs) were quantified with positron emission tomography. Abdominal SAT biopsies were collected to determine adipocyte morphology, gene expression markers of lipolysis, glucose and lipid metabolism and inflammation.Results Training increased glucose uptake in VAT (pConclusions Short-term training improves adipose tissue metabolism both in healthy and IR participants independently of the sex. Adipose tissue angiogenesis and gene expression was only significantly affected in IR participants.</div

Systemic cross-talk between brain, gut, and peripheral tissues in glucose homeostasis: effects of exercise training (CROSSYS). Exercise training intervention in monozygotic twins discordant for body weight

Background: Obesity and physical inactivity are major global public health concerns, both of which increase the risk of insulin resistance and type 2 diabetes. Regulation of glucose homeostasis involves cross-talk between the central nervous system, peripheral tissues, and gut microbiota, and is affected by genetics. Systemic cross-talk between brain, gut, and peripheral tissues in glucose homeostasis: effects of exercise training (CROSSYS) aims to gain new systems-level understanding of the central metabolism in human body, and how exercise training affects this cross-talk.Methods: CROSSYS is an exercise training intervention, in which participants are monozygotic twins from pairs discordant for body mass index (BMI) and within a pair at least the other is overweight. Twins are recruited from three population-based longitudinal Finnish twin studies, including twins born in 1983-1987, 1975-1979, and 1945-1958. The participants undergo 6-month-long exercise intervention period, exercising four times a week (including endurance, strength, and high-intensity training). Before and after the exercise intervention, comprehensive measurements are performed in Turku PET Centre, Turku, Finland. The measurements include: two positron emission tomography studies (insulin-stimulated whole-body and tissue-specific glucose uptake and neuroinflammation), magnetic resonance imaging (brain morphology and function, quantification of body fat masses and organ volumes), magnetic resonance spectroscopy (quantification of fat within heart, pancreas, liver and tibialis anterior muscle), echocardiography, skeletal muscle and adipose tissue biopsies, a neuropsychological test battery as well as biosamples from blood, urine and stool. The participants also perform a maximal exercise capacity test and tests of muscular strength.Discussion: This study addresses the major public health problems related to modern lifestyle, obesity, and physical inactivity. An eminent strength of this project is the possibility to study monozygotic twin pairs that share the genome at the sequence level but are discordant for BMI that is a risk factor for metabolic impairments such as insulin resistance. Thus, this exercise training intervention elucidates the effects of obesity on metabolism and whether regular exercise training is able to reverse obesity-related impairments in metabolism in the absence of the confounding effects of genetic factors