| 1. |
- Bellman, Jakob, et al.
(författare)
-
Loading enhances glucose uptake in muscles, bones, and bone marrow of lower extremities in humans.
- 2024
-
Ingår i: The Journal of clinical endocrinology and metabolism. - 1945-7197.
-
Tidskriftsartikel (refereegranskat)abstract
- Increased standing time has been associated with improved health, but the underlying mechanism is unclear.We herein investigate if increased weight loading increases energy demand and thereby glucose uptake (GU) locally in bone and/or muscle in the lower extremities.In this single-center clinical trial with randomized crossover design (ClinicalTrials.gov ID, NCT05443620), we enrolled 10 men with body mass index (BMI) between 30 and 35kg/m2. Participants were treated with both high load (standing with weight vest weighing 11% of body weight) and no load (sitting) on the lower extremities. GU was measured using whole-body quantitative positron emission tomography/computed tomography (PET/CT) imaging. The primary endpoint was the change in GU ratio between loaded bones (i.e. femur and tibia) and non-loaded bones (i.e. humerus).High load increased the GU ratio between lower and upper extremities in cortical diaphyseal bone (e.g. femur/humerus ratio increased by 19%, p=0.029), muscles (e.g. m. quadriceps femoris/m. triceps brachii ratio increased by 28%, p=0.014) and in certain bone marrow regions (femur/humerus diaphyseal bone marrow region ratio increased by 17%, p=0.041). Unexpectedly, we observed the highest GU in the bone marrow region of vertebral bodies, but its GU was not affected by high load.Increased weight-bearing loading enhances GU in muscles, cortical bone, and bone marrow of the exposed lower extremities. This could be interpreted as increased local energy demand in bone and muscle caused by increased loading. The physiological importance of the increased local GU by static loading remains to be determined.
|
|
| 2. |
- Garthwaite, Taru, et al.
(författare)
-
Associations of sedentary time, physical activity, and fitness with muscle glucose uptake in adults with metabolic syndrome
- 2022
-
Ingår i: Scandinavian Journal of Medicine and Science in Sports. - West Sussex : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 33:3, s. 353-358
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of the study was 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 [18F]FDG-PET imaging. Results: Sedentary time (β = −0.374), standing (β = 0.376), steps (β = 0.351), and VO2max (β = 0.598) were associated with muscle GU when adjusted for sex, age, and accelerometer wear time. Adjustment for body fat-% turned all associations non-significant. Conclusion: Body composition is a more important determinant of muscle GU in this population than sedentary time, physical activity, or fitness. © 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.
|
|
| 3. |
- Garthwaite, Taru, et al.
(författare)
-
Effects of reduced sedentary time on cardiometabolic health in adults with metabolic syndrome : A three-month randomized controlled trial
- 2022
-
Ingår i: Journal of Science and Medicine in Sport. - Chatswood : Elsevier Ltd. - 1440-2440 .- 1878-1861. ; 25:7, s. 579-585
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate if reducing sedentary behavior improves cardiometabolic biomarkers in adults with metabolic syndrome. Design: Randomized controlled trial. Methods: Sixty-four sedentary middle-aged adults with metabolic syndrome were randomized into intervention (INT; n = 33) and control (CON; n = 31) groups. INT was guided to limit sedentary behavior by 1 h/day through increased standing and light-intensity physical activity. CON was instructed to maintain usual habits. Sedentary behavior, breaks in sedentary behavior, standing, and physical activity were measured with hip-worn accelerometers for three months. Fasting blood sampling and measurements of anthropometrics, body composition, and blood pressure were performed at baseline and at three months. Linear mixed models were used for statistical analyses. Results: INT reduced sedentary behavior by 50 (95% CI: 24, 73) min/day by increasing light-intensity and moderate-to-vigorous physical activity (19 [8, 30] and 24 [14, 34] min/day, respectively). Standing increased also, but non-significantly (6 [−11, 23] min/day). CON maintained baseline activity levels. Significant intervention effects favoring INT occurred in fasting insulin (INT: 83.4 [68.7, 101.2] vs. CON: 102.0 [83.3, 125.0] pmol/l at three months), insulin resistance (HOMA-IR; 3.2 [2.6, 3.9] vs. 4.0 [3.2, 4.9]), HbA1c (37 [36, 38] vs. 38 [37, 39] mmol/mol), and liver enzyme alanine aminotransferase (28 [24, 33] vs. 33 [28, 38] U/l). Conclusions: Reducing sedentary behavior by 50 min/day and increasing light-intensity and moderate-to-vigorous activity showed benefits in several cardiometabolic biomarkers in adults with metabolic syndrome. Replacing some of the daily sedentary behavior with light-intensity and moderate-to-vigorous physical activity may help in cardiometabolic disease prevention in risk populations. © 2022 The Authors
|
|
| 4. |
- Garthwaite, Taru, et al.
(författare)
-
Standing is associated with insulin sensitivity in adults with metabolic syndrome
- 2021
-
Ingår i: Journal of Science and Medicine in Sport. - Chatswood : Elsevier. - 1440-2440 .- 1878-1861. ; 24:12, s. 1255-1260
-
Tidskriftsartikel (refereegranskat)abstract
- 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, standing, and PA were measured for four weeks with hip-worn accelerometers. VO2max (ml/min/kg) was measured with maximal cycle ergometry. Insulin sensitivity was determined by hyperinsulinaemic-euglycaemic clamp (M-value) and fasting blood sampling (HOMA-IR, insulin). Multivariable regression was used for analyses. Results: Sixty-four participants (37 women; 58.3 [SD 6.8] years) were included. Participants spent 10.0 (1.0) h sedentary, 1.8 (0.6) h standing, and 2.7 (0.6) h in PA and took 5149 (1825) steps and 29 (8) breaks daily. In sex-, age- and accelerometer wear time-adjusted model SB, standing, steps and VO2max were associated with M-value (β = −0.384; β = 0.400; β = 0.350; β = 0.609, respectively), HOMA-IR (β = 0.420; β = −0.548; β = −0.252; β = −0.449), and insulin (β = 0.433; β = −0.541; β = −0.252; β = −0.453); all p-values < 0.05. Breaks associated only with M-value (β = 0.277). When further adjusted for body fat %, only standing remained significantly associated with HOMA-IR (β = −0.381) and insulin (β = −0.366); significance was maintained even when further adjusted for SB, PA and fitness. Light and moderate-to-vigorous PA were not associated with insulin sensitivity. Conclusions: Standing is associated with insulin sensitivity markers. The association with HOMA-IR and insulin is independent of adiposity, PA, SB and fitness. Further studies are warranted, but these findings encourage replacing sitting with standing for potential improvements in insulin sensitivity in adults at increased type 2 diabetes risk. © 2021 The Authors.
|
|
| 5. |
- Haapala, Eero A., et al.
(författare)
-
Association between cardiorespiratory fitness and metabolic health in overweight and obese adults
- 2022
-
Ingår i: Journal of Sports Medicine and Physical Fitness. - Turin : Edizioni Minerva Medica. - 0022-4707 .- 1827-1928. ; 62:11, s. 1526-1533
-
Tidskriftsartikel (refereegranskat)abstract
- 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 associations of peak oxygen uptake (V?O2peak) and peak power output (Wpeak) scaled either by BM-1, fat free mass (FFM-1), or by allometric methods with individual cardiometabolic risk factors and clustering of cardiometabolic risk factors in 55 overweight or obese adults with metabolic syndrome. METHODS: VO2peak and Wpeak were assessed by a maximal cycle ergometer exercise test. FFM was measured by air displacement plethysmo- graph and glucose, insulin, HbA1c, triglycerides, and total, LDL, and HDL cholesterol from fasting blood samples. HOMA-IR and metabolic syndrome score (MetS) were computed. RESULTS: VO2peak and Wpeak scaled by BM-1 were inversely associated with insulin (β=-0.404 to -0.372, 95% CI: -0.704 to -0.048), HOMAIR (β=-0.442 to -0.440, 95% CI: -0.762 to -0.117), and MetS (β=-0.474 to -0.463, 95% CI: -0.798 to -0.127). Other measures of CRF were not associated with cardiometabolic risk factors. CONCLUSIONS: Our results suggest that using BM-1 as a scaling factor confounds the associations between CRF and cardiometabolic risk in overweight/obese adults with the metabolic syndrome. © 2022 EDIZIONI MINERVA MEDICA.
|
|
| 6. |
- Kudomi, Nobuyuki, et al.
(författare)
-
Myocardial Blood Flow and Metabolic Rate of Oxygen Measurement in the Right and Left Ventricles at Rest and During Exercise Using 15O-Labeled Compounds and PET
- 2019
-
Ingår i: Frontiers in Physiology. - Lausanne : Frontiers Media S.A.. - 1664-042X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- 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 method to measure MBF, OEF, and MVO2 simultaneously both in the RV and LV free wall (FW) using positron emission tomography in healthy young men at rest and during supine bicycle exercise. Results: Resting MBF was not significantly different between the three myocardial regions. Exercise increased MBF in the LVFW and septum, but MBF was lower in the RV compared to septum and LVFW during exercise. Resting OEF was similar between the three different myocardial regions (similar to 70%) and increased in response to exercise similarly in all regions. MVO2 increased approximately two to three times from rest to exercise in all myocardial regions, but was significantly lower in the RV during exercise as compared to septum LVFW. Conclusion: MBF, OEF, and MVO2 can be assessed simultaneously in the RV and LV myocardia at rest and during exercise. Although there are no major differences in the MBF and OEF between LV and RV myocardial regions in the resting myocardium, MVO2 per gram of myocardium appears to be lower the RV in the exercising healthy human heart due to lower mean blood flow. The presented method may provide valuable insights for the assessment of MBF, OEF and MVO2 in hearts in different pathophysiological states.
|
|
| 7. |
|
|
| 8. |
- Laaksonen, Marko, 1975-, et al.
(författare)
-
Left-ventricular hypertrophy associates to impaired maximal myocardial perfusion in endurance-trained men
- 2009
-
Konferensbidrag (refereegranskat)abstract
- Long-term endurance training induces morphological adaptations in heart, such as left-ventricular (LV) hypertrophy caused by wall thickening and cavity enlargement. Interestingly, these anatomical changes in the heart are strikingly similar to certain pathophysiological changes (Pellicia 2000). Previous studies have shown that the perfusion response in myocardium during dipyridamole- or adenosine infusion is decreased in several pathophysiological states with LV hypertrophy (e.g. Stolen et al. 2004). However, studies in endurance athletes with LV hypertrophy have shown contradictory results on myocardial perfusion response ranging from reduced to increased myocardial perfusion during dipyridamole- or adenosine-induced vasodilation compared to untrained men (Kjaer et al. 2005; Kalliokoski et al. 2002). The degree of hypertrophy could explain the discrepant findings in studies in athletes, but it has not been thoroughly investigated. Thus, we examined totally 31 endurance athletes (ET) and 25 untrained (UT) men in order to study the association between myocardial functional and anatomical parameters measured with echocardiography, and myocardial perfusion (at rest and during maximal vasodilation induced by iv adenosine) measured with Positron Emission Tomography. Both VO2max (60+-5 vs 42+-8 ml/kg/min, p<0.001) and LVmass index (169+-27 vs 102+-15 g/m2, p<0.001) were markedly higher in ET. Resting myocardial perfusion was similar between the groups (ET 0.7+-0.2 vs UT 0.8+-0.2 ml/g/min, p=0.22) whereas adenosine-stimulated perfusion was lower in ET (2.9+-1.0 vs 3.7+-1.0 ml/g/min, p<0.01). VO2max correlated inversely with adenosine-stimulated perfusion in ET (r=-0.39, p=0.03) and with resting perfusion in UT (-0.49, p=0.01). Forward LV work correlated linearly with resting perfusion in both groups (ET r=0.54, p<0.01; UT r=0.50, p=0.01). ET group was further divided into three subgroups according to LVmass index (ET1: LVmass index <150g/m2, n=9; ET2 LVmass index 150-180 g/m2, n=12; ET3 LVmass index >180 gm2, n=10). Adenosine-induced myocardial perfusion decreased gradually when LVmass increased (UT 3.7+-1.+0 vs ET1 3.3+-0.9 vs ET2 2.7+-1.4 vs ET3 2.6+-0.5 mL g-1 min-1, p=0.008). LVmass index was also inversely related to adenosine-induced perfusion in entire study population (r=-0.46, p<0.01). Therefore, these results suggest that endurance training-induced severe cardiac hypertrophy impairs myocardial perfusion capacity. Kalliokoski K et al. (2002) Med Sci Sports Exerc 34:948-53 Kjaer A et al. (2005) Am J Cardiol 96:1692-98 Pellicia A (2000) Curr Cardiol Rep 2(2):166-71 Stolen KQ et al (2004) 10(2):132-40
|
|
| 9. |
- Laaksonen, Marko, 1975-, et al.
(författare)
-
Muscle free fatty-acid uptake associates to mechanical efficiency during exercise in humans
- 2018
-
Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 9:AUG
-
Tidskriftsartikel (refereegranskat)abstract
- Intrinsic factors related to muscle metabolism may explain the differences in mechanical efficiency (ME) during exercise. Therefore, this study aimed to investigate the relationship between muscle metabolism and ME. Totally 17 healthy recreationally active male subjects were recruited and divided into efficient (EF; n=8) and inefficient (IE; n=9) groups, which were matched for age (mean±SD 24±2 vs. 23±2 yrs), BMI (23±1 vs. 23±2 kg m-2), physical acitivity levels (3.4±1.0 vs. 4.1±1.0 sessions/week), and V ̇O2peak (53±3 vs. 52±3 mL kg-1 min-1), respectively, but differed for ME at 45% of VO2peak intensity during submaximal bicycle ergometer test (EF 20.5±3.5 vs. IE 15.4±0.8 %, P < 0.001). Using Positron Emission Tomography, muscle blood flow (BF) and uptakes of oxygen (mVO2), fatty acids (FAU) and glucose (GU) were measured during dynamic submaximal knee-extension exercise. Workload-normalized BF (EF 35±14 vs. IE 34±11 mL 100g-1 min-1, P = 0.896), mVO2 (EF 4.1±1.2 vs. IE 3.9±1.2 mL 100g-1 min-1, P = 0.808), and GU (EF 3.1±1.8 vs. IE 2.6±2.3 μmol 100g-1 min-1, P = 0.641) as well as the delivery of oxygen, glucose, and fatty acids, as well as respiratory quotient were not different between the groups. However, FAU was significantly higher in EF than IE (3.1±1.7 vs. 1.7±0.6 μmol 100g-1 min-1, P < 0.047) and it also correlated with ME (r=0.56, P < 0.024) in the entire study group. EF group also demonstrated higher use of plasma fatty acids than IE, but no differences in use of plasma glucose and intramuscular energy sources were observed between the groups. These findings suggest that the effective use of plasma fatty acids is an important determinant of mechanical efficiency during exercise.
|
|
| 10. |
- Laaksonen, Marko, 1975-, et al.
(författare)
-
Perfusion heterogeneity does not explain excess muscle oxygen uptake during variable intensity exercise
- 2010
-
Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:4, s. 241-249
-
Tidskriftsartikel (refereegranskat)abstract
- The association between muscle oxygen uptake (VO2) and perfusion or perfusion heterogeneity (relative dispersion, RD) was studied in eight healthy male subjects during intermittent isometric (1 s on, 2 s off) one-legged knee-extension exercise at variable intensities using positron emission tomography and a-v blood sampling. Resistance during the first 6 min of exercise was 50% of maximal isometric voluntary contraction force (MVC) (HI-1), followed by 6 min at 10% MVC (LOW) and finishing with 6 min at 50% MVC (HI-2). Muscle perfusion and O2 delivery during HI-1 (26 ± 5 and 5·4 ± 1·0 ml 100 g−1 min−1) and HI-2 (28 ± 4 and 5·8 ± 0·7 ml 100 g−1 min−1) were similar, but both were higher (P<0·01) than during LOW (15 ± 3 and 3·0 ± 0·6 ml 100 g−1 min−1). Muscle VO2 was also higher during both HI workloads (HI-1 3·3 ± 0·4 and HI-2 4·1 ± 0·6 ml 100 g−1 min−1) than LOW (1·4 ± 0·4 ml 100 g−1 min−1; P<0·01) and 25% higher during HI-2 than HI-1 (P<0·05). O2 extraction was higher during HI workloads (HI-1 62 ± 7 and HI-2 70 ± 7%) than LOW (45 ± 8%; P<0·01). O2 extraction tended to be higher (P = 0·08) during HI-2 when compared to HI-1. Perfusion was less heterogeneous (P<0·05) during HI workloads when compared to LOW with no difference between HI workloads. Thus, during one-legged knee-extension exercise at variable intensities, skeletal muscle perfusion and O2 delivery are unchanged between high-intensity workloads, whereas muscle VO2 is increased during the second high-intensity workload. Perfusion heterogeneity cannot explain this discrepancy between O2 delivery and uptake. We propose that the excess muscle VO2 during the second high-intensity workload is derived from working muscle cells.
|
|
