Ilkka HeinonenUniversity of Turku | UTU · Turku PET Centre
Ilkka Heinonen
PhD, Adjunct Professor
About
145
Publications
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Introduction
My primary general research interest is to elucidate acute and long-term cardiovascular and metabolic adaptations of physical activity and exercise in health and disease. Novel aspects in this area are pursued by studying broad range of human activity levels, ranging from total inactivity at the epidemiological scale to extreme activities of highly training and performing endurance athletes. These studies are complemented by investigating physiological responses of environmental challenges.
Additional affiliations
Education
August 2007 - December 2011
January 2006 - February 2010
August 2003 - December 2007
Publications
Publications (145)
The aim of this study was to investigate whether a reduction in accelerometer-measured sedentary behavior (SB) improves blood lipids in inactive adults with metabolic syndrome (MetS). Sixty-four participants were randomly assigned into intervention (INT, n = 33) and control (CONT, n = 31) groups. The INT group was instructed to reduce SB by 1 h/day...
Objectives
Sedentary behaviour (SB) is a plausible intervention target for back pain mitigation. Therefore, this study aimed to investigate the effects of a 6-month SB reduction intervention on back pain and related disability outcomes, and paraspinal muscle (ie, erector spinae and transversospinales separately) insulin sensitivity (glucose uptake,...
Background
Obesity is associated with impaired glucose metabolism and hepatic insulin resistance. The aim was to investigate the associations of hepatic glucose uptake (HGU) and endogenous glucose production (EGP) to sedentary behavior (SB), physical activity (PA), cardiorespiratory fitness, dietary factors, and metabolic risk markers.
Methods
For...
Background
Mobilization of certain immune cells may improve the ability of the immune system to combat tumor cells, but the effect of acute exercise on mobilizing immune cells has been sparsely investigated in cancer patients. Therefore, we examined how acute exercise influences circulating immune cells in breast cancer patients.
Methods
Nineteen...
Background
The effects of reducing sedentary behaviour (SB) on cardiac structure and function remain unknown, yet reducing SB may have potential for heart failure prevention.
Purpose
The aim of this study was to investigate whether reducing SB could lead to healthy cardiac remodelling.
Methods
Sixty-four physically inactive adults with metabolic...
Heart depends critically on continuous supply of blood, but it is unknown whether cancer, without any treatments, affects myocardial blood flow (MBF) at rest or during exercise. This study therefore aimed at measuring MBF in cancer patients and control subjects and it was hypothesized that MBF is affected by cancer. The study included recently-diag...
Introduction: The possible beneficial effects of physical activity during doxorubicin treatment of breast cancer need further investigation as many of the existing studies have been done on non-tumor-bearing models. Therefore, in this study, we aim to assess whether short-term voluntary wheel-running exercise during doxorubicin treatment of breast...
Physical activities and sedentary behaviors take place in different contexts. This study aimed to determine if the context, total score, and leisure-time MET-index assessed by the Baecke questionnaire associate with each other or with sedentary behavior and physical activity outcomes from a 4-week accelerometer measurement in physically inactive ad...
Sedentary behavior, defined as sitting with low energy expenditure, has emerged as a modifiable risk factor that affects our physiology and health. Evidence for the detrimental effects of sedentary behavior/physical inactivity on health, however, stems largely from epidemiological studies, which cannot address causalities. Acute and short-term sede...
Metabolic flexibility (MetFlex) describes the ability to respond and adapt to changes in metabolic demand and substrate availability. The relationship between physical (in)activity and MetFlex is unclear. This study aimed to determine whether sedentary time, physical activity (PA), and cardiorespiratory fitness associate with MetFlex. Sedentary tim...
Evidence on the long-term effects of reducing sedentary behaviour (SB) on blood pressure (BP) is scarce. Therefore, we performed a sub-analysis of the BP effects of a six-month intervention that aimed at reducing SB by 1 h/day and replacing it with non-exercise activities. Sixty-four physically inactive and sedentary adults with metabolic syndrome...
Sedentary behavior (SB) and physical inactivity associate with impaired insulin sensitivity. We investigated whether an intervention aimed at a 1h reduction in daily SB during 6 months would improve insulin sensitivity in the weight-bearing thigh muscles. Forty-four sedentary inactive adults [mean age 58 (SD 7) years; 43% men] with metabolic syndro...
Introduction: Exercise training is known to improve left ventricular (LV) function, but the mechanisms remain incompletely understood. Here we investigated the structural and functional adaptations in the LV in response to 2-months of aerobic exercise training in Göttingen minipigs. Methods: Adult male Göttingen minipigs were randomized to an aerob...
The role of exercise in cancer prevention and control is increasingly recognized, and based on preclinical studies, it is hypothesized that mobilization of leukocytes plays an important role in the anti-tumor effect. Thus, we examined how 10-min acute exercise modulates immune cells in newly diagnosed breast cancer patients. Blood samples were take...
Introduction
Poor cardiorespiratory fitness (CRF) is associated with adverse health outcomes. Previous observational and cross‐sectional studies have suggested that reducing sedentary behavior (SB) might improve CRF. Therefore, we investigated the effects of a 6‐month intervention of reducing SB on CRF in 64 sedentary inactive adults with metabolic...
Background: Studies have shown that acute exercise can mobilize several leukocyte subpopulations in healthy individuals. Our aim was to investigate whether a 10-min acute exercise has an effect on immune cell proportions in lymphoma patients.
Methods: This study included seven lymphoma patients referred to curative oncologic therapy. Three had Hodg...
Objective
To investigate the associations of sedentary time, physical activity, and cardiorespiratory fitness with skeletal muscle glucose uptake (GU).
Methods
Sedentary time and physical activity were measured with accelerometers, and VO2max with cycle ergometry in 44 sedentary adults with metabolic syndrome. Thigh muscle GU was determined with [...
Background:
This study examined whether hemoglobin (Hb) and white blood cell count (WBC) associate with body adiposity and other cardiometabolic risk factors, as well as accelerometer-measured sedentary behavior (SB) and physical activity (PA), when adjusted for body mass index (BMI).
Methods:
The cross-sectional analysis included 144 participan...
The aim of this study was to investigate the associations between liver fat content (LFC), sedentary behaviour (SB), physical activity (PA), fitness, diet, body composition, and cardiometabolic risk factors in adults with metabolic syndrome. A total of 44 sedentary adults (mean age 58 [SD 7] years; 25 women) with overweight or obesity participated....
Purpose:
To investigate whether a reduction in daily sedentary behavior (SB) improves insulin sensitivity in adults with metabolic syndrome in 6 months, without adding intentional exercise training.
Methods:
Sixty-four sedentary inactive middle-aged adults with overweight and metabolic syndrome [mean age 58 (SD 7) years, mean BMI 31.6 (SD 4.3) k...
The aim of this study was to investigate whether melanoma impairs intrinsic heart function in mice and whether short‐term voluntary running wheel exercise could reduce the possible negative effects. Additionally, we investigated whether changes in cell size, capillary density, calcium channel levels, metabolic enzyme activities or oxidative stress...
The aim of this study was to investigate whether subcutaneous melanoma impairs intrinsic cardiac function and hypoxia tolerance in mice. Additionally it was investigated whether these changes could be prevented by voluntary running-wheel exercise. The role of different molecular pathways were also analysed. Male mice (C57Bl/6NCrl) were divided into...
Objectives
The aim was to investigate if reducing sedentary behavior (SB) improves cardiometabolic biomarkers in adults with metabolic syndrome (MetS).
Design
Randomized controlled trial.
Methods
Sixty-four sedentary middle-aged adults with MetS were randomized into intervention (INT; n = 33) and control (CON; n = 31) groups. INT was guided to li...
Purpose:
The muscle perfusion response to post-exercise cold water immersion (CWI) is not well understood. We examined the effects of graded post-exercise CWI upon global and regional quadriceps femoris muscle perfusion using positron emission tomography (PET) and [15O]H2O.
Methods:
Using a matched-group design, 30 healthy men performed cycle er...
Background:
Cardiorespiratory fitness (CRF) has been inversely associated with insulin resistance and clustering of cardiometabolic risk factors among overweight and obese individuals. However, most previous studies have scaled CRF by body mass (BM) possibly inflating the association between CRF and cardiometabolic health. We investigated the asso...
The REACT is a commercial activity tracker based intervention, which primarily aimed to increase physical activity. This study examines the secondary outcomes of the physical activity intervention on body composition and cardiometabolic health indicators. Overall 231 recently retired Finnish men and women [65.2 (SD 1.1) years, 83% women] took part...
Objectives
The association between the subjective experience of pain-related disability (PRD) and device-measured physical activity (PA) and sedentary behavior (SB) in overweight and obese adults is not well known. The aim of this study was to investigate the associations of pain markers with accelerometer-measured SB duration and different intensi...
Exercise is known to improve cardiac recovery following coronary occlusion. However, whether short-term exercise can improve cardiac function and hypoxia tolerance ex vivo independent of reperfusion injury and the possible role of calcium channels in improved hypoxia tolerance remains unknown. Therefore, in the current study, heart function was mea...
Objectives
To determine how components of accelerometer-measured sedentary behavior (SB) and physical activity (PA), and fitness are associated with insulin sensitivity in adults with metabolic syndrome.
Design
Cross-sectional.
Methods
Target population was middle-aged (40-65 years) sedentary adults with metabolic syndrome. SB, breaks in SB, stan...
Accelerometry is a commonly used method to determine physical activity in clinical studies, but the duration and timing of measurement have seldom been addressed. We aimed to evaluate possible changes in the measured outcomes and associations with insulin resistance during four weeks of accelerometry data collection. This study included 143 partici...
Objective
We studied the associations between accelerometer-measured sedentary behavior (SB) and habitual physical activity (PA) as well as markers of body adiposity and other cardiometabolic risk factors with liver enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamyltransferase (GGT).
Methods
A total of 144 midd...
Background
Effective strategies to reverse the increasing trend of sedentary behavior after retirement are needed. The aim of this study was to examine the effect of 12-month activity tracker-based intervention on daily total and prolonged sedentary time (≥60 min) among recent retirees.
Methods
Randomization to intervention and control groups was...
Purpose:
The randomized controlled trial REACT (NCT03320746) examined the effect of a 12-month consumer-based activity tracker intervention on accelerometer-measured physical activity among recent retirees.
Methods:
Altogether 231 recently retired Finnish adults (age, 65.2 ± 1.1 yr, mean ± SD; 83% women) were randomized to intervention and contr...
Objective:
Whereas insulin resistance is expressed as reduced glucose uptake in peripheral tissues, the relationship between insulin resistance and brain glucose metabolism remains controversial. Our aim was to examine the association of insulin resistance and brain glucose uptake (BGU) during a euglycemic hyperinsulinemic clamp in a large sample...
It is well known that high von Willebrand factor (VWF) and factor VIII (FVIII) levels are associated with an increased risk of cardiovascular disease. It is still debated whether VWF and FVIII are biomarkers of endothelial dysfunction and atherosclerosis or whether they have a direct causative role. Therefore, we aimed to unravel the pathophysiolog...
Background: Postprandial glucose, insulin, and triglyceride metabolism is impaired by prolonged sitting, but enhanced by exercise. The aim of this study was to assess the effects of a continuous exercise bout with and without intermittent active interruptions to prolonged sitting on postprandial glucose, insulin, and triglycerides.
Methods: Seden...
The aim of this study was to examine the associations of cardiometabolic health markers with device-measured sedentary behavior (SB) duration and different intensities of physical activity (PA) among overweight working-aged adults with low self-reported PA levels. This cross-sectional analysis included 144 subjects (42 men) with mean age of 57 (SD...
Purpose
Rac1 and its downstream target PAK1 are novel regulators of insulin and exercise-induced glucose uptake in skeletal muscle. However, it is not yet understood how different training intensities affect the expression of these proteins. Therefore, we studied the effects of high-intensity interval training (HIIT) and moderate-intensity continuo...
The prevalence of diabetic metabolic derangement (DMetD) has increased dramatically over the last decades. Although there is increasing evidence that DMetD is associated with cardiac dysfunction, the early DMetD-induced myocardial alterations remain incompletely understood. Here, we studied early DMetD-related cardiac changes in a clinically releva...
We examined the influence of graded cold-water immersion (CWI) on global and regional quadriceps muscle perfusion using positron emission tomography (PET) and [ ¹⁵ O]H 2 O. In thirty healthy males (33±8 yrs; 81±10 kg; 184±5 cm; percentage body fat: 13±5%; V̇O 2peak : 47±8 mL·kg ⁻¹ ·min ⁻¹ ) quadriceps perfusion, thigh and calf cutaneous vascular co...
Introduction
Comorbidities such as diabetes mellitus (DM), hypercholesterolemia (HC) and chronic kidney disease (CKD), are often associated with altered coronary microvascular function. However, the specific mechanisms affected by the various comorbidities have not been investigated in detail. Here we studied endothelium‐dependent and ‐independent...
Aims: Simultaneous measurement of right (RV) and left ventricle (LV) myocardial blood flow (MBF), oxygen extraction fraction (OEF), and oxygen consumption (MVO2) non-invasively in humans would provide new possibilities to understand cardiac physiology and different patho-physiological states. Methods: We developed and tested an optimized novel meth...
Background:
Altitude training stimulates erythropoietin hormone (EPO) release and increases blood hemoglobin (Hb) mass, which may result in improved oxygen (O2) transport capacity. It was hypothesized in the present study that periodic inhalation of carbon monoxide (CO) might elicit similar physiological adaptations compared to altitude training....
Background
Retirement is associated with an increase in self-reported daily sedentary time, but no longitudinal evidence exists on how objectively measured sedentary time changes during retirement transition. The aim of this study was to compare objectively measured daily and hourly sedentary time before and after retirement and examine whether the...
Background
Sedentary behaviour is associated with impaired cognition, whereas exercise can acutely improve cognition.
Objective
We compared the effects of a morning bout of moderate-intensity exercise, with and without subsequent light-intensity walking breaks from sitting, on cognition in older adults.
Methods
Sedentary overweight/obese older ad...
The effects of sprint interval training (SIT) on intramyocellular (IMCL) and extramyocellular (EMCL) lipid accumulation are unclear. We tested the effects of SIT and moderate‐intensity continuous training (MICT) on IMCL and EMCL accumulation in a randomized controlled setting in two different study populations; healthy untrained men (n 28) and subj...
Preventing declines in cerebral blood flow is important for maintaining optimal brain health with aging. We compared the effects of a morning bout of moderate-intensity exercise, with and without subsequent light-intensity walking breaks from sitting, on cerebral blood flow velocity over 8-hours in older adults. In a randomized crossover trial, ove...
Comorbidities such as diabetes mellitus (DM), hypercholesterolemia (HC) and chronic kidney disease (CKD), are often associated with diastolic dysfunction. We tested the hypothesis that the co‐morbidities produce systemic inflammation and microvascular dysfunction resulting in impaired myocardial perfusion, structural changes in the myocardium as we...
Objective Skeletal muscle is unique among organs in that its blood flow, thus oxygen supply that is critical for muscular function, can change over a remarkably large range. Compared to the rest, muscle blood flow can increase over 20-fold during intense exercise. Positron emission tomography (PET) and [15O]-H2O tracer provide a unique tool for the...
Human bone marrow is a metabolically active tissue that responds to acute low intensity exercise by having increased glucose uptake. Here we studied whether bone marrow glucose uptake increases more with increased exercise intensities. Femoral bone marrow glucose uptake was measured using positron emission tomography and 18F-fluoro-deoxyglucose in...
Left ventricular (LV) diastolic dysfunction is one of the important mechanisms responsible for symptoms in patients with heart failure. The aim of the current study was to identify parameters that may be used to detect early signs of LV diastolic dysfunction in diabetic pigs on a high fat diet, using conventional and speckle tracking echocardiograp...
Aims
More than 50% of patients with heart failure have preserved ejection fraction characterized by diastolic dysfunction. The prevalance of diastolic dysfunction is higher in females and associates with multiple comorbidities such as hypertension (HT), obesity, hypercholesterolemia (HC), and diabetes mellitus (DM). Although its pathophysiology rem...
The mechanisms that regulate bone blood flow (BBF) in humans are largely unknown. Animal studies suggest that nitric oxide (NO) could be involved and in the present study we investigated the effects of inhibition of nitric oxide synthase (NOS) alone and in combination with inhibition of cyclooxygenase (COX) enzyme, thus prostaglandin (PG) synthesis...
Growing concerns have been expressed regarding cardiovascular performance in modern farm pigs, which has been proposed as a critical factor contributing to the reduced adaptability of modern pigs to stress. Here we tested the hypothesis that cardiac dimensions and pump function in modern heavy farm pigs are disproportionally low for their body weig...
Environmental stress such as extremely warm or cold temperature is often considered a challenge to human health and body homeostasis. However, human body can adapt relatively well to heat and cold environments and recent studies have also elucidated that particularly heat stress might be even highly beneficial for human health. Consequently, the ai...
Type 2 diabetes mellitus (T2DM) is associated with reduced myocardial glucose uptake (GU) and increased free fatty acid uptake (FFAU). Sprint interval training (SIT) improves physical exercise capacity and metabolic biomarkers, but effects of SIT on cardiac function and energy substrate metabolism in diabetic subjects are unknown. We tested the hyp...
We previously demonstrated that uridine adenosine tetraphosphate (Up4A) induces potent and partially endothelium-dependent relaxation in the healthy porcine coronary microvasculature. We subsequently showed that Up4A-induced porcine coronary relaxation was impaired via downregulation of P1 receptors after myocardial infarction. In view of the delet...
Background:
Apelin is a hormone that regulates cardiovascular function, and its concentration is increased by hypoxia based on cell culture and animal studies. As it remains unknown as to whether hypoxia could affect apelin levels in humans, we investigated whether breathing normobaric hypoxic gas mixture increases the circulating apelin concentra...
Over the last 50 years, a vast amount of knowledge pertaining to the structure and control mechanisms that govern function of the coronary circulation has been obtained through experimental animal studies. Indeed, studies in a variety of animal models have provided us with a basic understanding of the major factors determining myocardial blood flow...