Peak fat oxidation, peak oxygen uptake, and running performance increase during pre-season in sub-elite male football players.

PURPOSE: In Football, the high-intensity running bouts during matches are considered decisive. Interestingly, recent studies showed that peak fat oxidation rates (PFO) are higher in football players than other athletes. This study aimed to investigate whether PFO increases following a pre-season. Secondarily, and due to COVID-19, we investigated whether PFO is related to the physical performance in a subgroup of semi-professional male football players. METHODS: Before and after 8 weeks of pre-season training, 42 sub-elite male football players (18 semi-professionals and 24 non-professionals) had a dual-energy x-ray absorptiometry scan and performed a graded exercise test on a treadmill for the determination of PFO, the exercise intensity eliciting PFO (Fatmax) and peak oxygen uptake (V̇O2peak). Additionally, the semi-professional players performed a Yo-Yo Intermittent Recovery Test level 2 (YYIR2) before and after pre-season training to determine football-specific running performance. RESULTS: PFO increased by 11 ± 10% (mean ± 95% CI), p = 0.031, and V̇O2peak increased by 5 ± 1%, p < 0.001, whereas Fatmax was unchanged (+12 ± 9%, p = 0.057), following pre-season training. PFO increments were not associated with increments in V̇O2peak (Pearson's r2 = 0.00, p = 0.948) or fat-free mass (FFM) (r2 = 0.00, p = 0.969). Concomitantly, YYIR2 performance increased in the semi-professional players by 39 ± 17%, p < 0.001, which was associated with changes in V̇O2peak (r2 = 0.35, p = 0.034) but not PFO (r2 = 0.13, p = 0.244). CONCLUSIONS: PFO, V̇O2peak, and FFM increased following pre-season training in sub-elite football players. However, in a subgroup of semi-professional players, increments in PFO were not associated with improvements in YYIR2 performance nor with increments in V̇O2peak and FFM.

Effect of repeated prolonged exercise on liver fat content and visceral adipose tissue in well-trained older men.

INTRODUCTION: Liver fat (LF) and visceral adipose tissue (VAT) content decreases with training, however, this has mainly been investigated in sedentary obese or healthy participants. The aim of this study was to investigate the effects of repeated prolonged exercise on LF and VAT content in well-trained older men and to compare baseline LF and VAT content to recreationally active older men. METHOD: A group of five well-trained older men were tested before and after cycling a total distance of 2558 km in 16 consecutive days. VAT content and body composition was measured using DXA before a bicycle ergometer test was performed to determine maximal fat oxidation (MFO), maximal oxygen consumption ( VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ ), and the relative intensity at which MFO occurred (Fatmax). LF content was measured on a separate day using MRI. For comparison of baseline values, a control group of eight healthy age- and BMI-matched recreationally active men were recruited. RESULTS: The well-trained older men had lower VAT (p = 0.02), and a tendency toward lower LF content (p = 0.06) compared with the control group. The intervention resulted in decreased LF content (p = 0.02), but VAT, fat mass, and lean mass remained unchanged. VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ , MFO, and Fatmax were not affected by the intervention. CONCLUSION: The study found that repeated prolonged exercise reduced LF content, but VAT and VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ remained unchanged. Aerobic capacity was aligned with lower LF and VAT in older active men.

The effect of 8 weeks of physical training on muscle performance and maximal fat oxidation rates in patients treated with simvastatin and coenzyme Q10 supplementation.

Statins are prescribed for the treatment of elevated cholesterol, but they may negatively affect metabolism, muscle performance, and the response to training. Coenzyme Q10 (CoQ10) supplementation may alleviate these effects. Combined simvastatin and CoQ10 treatment during physical training has never been tested. We studied the response to 8 weeks training (maximal oxygen uptake ( V̇O2max${\dot{V}_{{{\rm{O}}_{\rm{2}}}{\rm{max}}}}$ ), fat oxidation (MFO), the workload at which MFO occurred, and muscle strength) in statin naive dyslipidaemic patients who received simvastatin (40 mg/day) with (S + Q, n = 9) or without (S + Pl, n = 10) CoQ10 supplementation (2 × 200 mg/day) or placebo (Pl + Pl, n = 7) in a randomized, double-blind placebo-controlled study. V̇O2max${\dot{V}_{{{\rm{O}}_{\rm{2}}}{\rm{max}}}}$ and maximal workload increased with training (main effect of time, P < 0.05). MFO increased from 0.29 ± 0.10, 0.26 ± 0.10, and 0.38 ± 0.09 to 0.42 ± 0.09, 0.38 ± 0.10 and 0.48 ± 0.16 g/min in S + Q, S + Pl, and Pl + Pl, respectively (main effect of time, P = 0.0013). The workload at MFO increased from 75 ± 25, 56 ± 23, and 72 ± 17 to 106 ± 25, 84 ± 13 and 102 ± 31 W in S + Q, S + Pl, and Pl + Pl, respectively (main effect of time, P < 0.0001). Maximal voluntary contraction and rate of force development were unchanged. Exercise improved aerobic physical capacity and simvastatin with or without CoQ10 supplementation did not inhibit this adaptation. The similar increases in MFO and in the workload at which MFO occurred in response to training shows that the ability to adapt substrate selection and oxidation rates is preserved with simvastatin treatment, despite the potential negative impact of simvastatin at the mitochondrial level. CoQ10 supplementation does not augment this adaptation. KEY POINTS: Simvastatins are prescribed for treatment of elevated cholesterol, but they may negatively affect metabolism, muscle performance and the response to training. Coenzyme Q10 (CoQ10) supplementation may alleviate some of these effects. We found that simvastatin treatment does not negatively affect training-induced adaptations of substrate oxidation during exercise. Likewise, maximal oxygen uptake increases with physical training also in patients in treatment with simvastatin. CoQ10 supplementation in simvastatin-treated patients presents no advantage in the adaptations to physical training Simvastatin treatment decreases plasma concentrations of total CoQ10, but this can be alleviated by simultaneous supplementation with CoQ10.

The relationship between peak fat oxidation and prolonged double-poling endurance exercise performance.

The peak fat oxidation rate (PFO) and the exercise intensity that elicits PFO (Fatmax ) are associated with endurance performance during exercise primarily involving lower body musculature, but it remains elusive whether these associations are present during predominant upper body exercise. The aim was to investigate the relationship between PFO and Fatmax determined during a graded exercise test on a ski-ergometer using double-poling (GET-DP) and performance in the long-distance cross-country skiing race, Vasaloppet. Forty-three healthy men completed GET-DP and Vasaloppet and were divided into two subgroups: recreational (RS, n = 35) and elite (ES, n = 8) skiers. Additionally, RS completed a cycle-ergometer GET (GET-Cycling) to elucidate whether the potential relationships were specific to exercise modality. PFO (r2  = .10, P = .044) and Fatmax (r2  = .26, P < .001) were correlated with performance; however, V ˙ O 2 peak was the only independent predictor of performance (adj. R2  = .36) across all participants. In ES, Fatmax was the only variable associated with performance (r2  = .54, P = .038). Within RS, DP V ˙ O 2 peak (r2  = .11, P = .047) and ski-specific training background (r2  = .30, P = .001) were associated with performance. Between the two GETs, Fatmax (r2  = .20, P = .006) but not PFO (r2  = .07, P = .135) was correlated. Independent of exercise mode, neither PFO nor Fatmax were associated with performance in RS (P > .05). These findings suggest that prolonged endurance performance is related to PFO and Fatmax but foremost to V ˙ O 2 peak during predominant upper body exercise. Interestingly, Fatmax may be an important determinant of performance among ES. Among RS, DP V ˙ O 2 peak , and skiing experience appeared as performance predictors. Additionally, whole-body fat oxidation seemed specifically coupled to exercise modality.

Inflammatory biomarkers in patients in Simvastatin treatment: No effect of co-enzyme Q10 supplementation.

PURPOSE: Atherosclerosis is a major risk factor for cardiovascular disease (CVD) and is known to be an inflammatory process. Statin therapy decreases both cholesterol and inflammation and is used in primary and secondary prevention of CVD. However, a statin induced decrease of plasma concentrations of the antioxidant coenzyme Q10 (CoQ10), may prevent the patients from reaching their optimal anti-inflammatory potential. Here, we studied the anti-inflammatory effect of Simvastatin therapy and CoQ10 supplementation. METHODS: 35 patients in primary prevention with Simvastatin (40 mg/day) were randomized to receive oral CoQ10 supplementation (400 mg/d) or placebo for 8 weeks. 20 patients with hypercholesterolemia who received no cholesterol-lowering treatment was a control group. Plasma concentrations of lipids and inflammatory biomarkers (interleukin-6 (IL6); -8 (IL8); -10 (IL10), tumor necrosis factor-α (TNFα); high-sensitivity C reactive protein (hsCRP)) as well as glycated hemoglobin (HbA1c) were quantified before and after the intervention. RESULTS: No significant change in inflammatory markers or lipids was observed after CoQ10 supplementation Patients in Simvastatin therapy had significantly (P < 0.05) lower baseline concentration of IL6 (0.31 ±â€¯0.03 pg/ml), IL8 (1.6 ±â€¯0.1 pg/ml) IL10 (0.16 ±â€¯0.02 pg/ml) and borderline (P = 0.053) lower TNFα (0.88 ±â€¯0.05 pg/ml), but not hsCRP (1.34 ±â€¯0.19 mg/l) compared with the control group (0.62 ±â€¯0.08, 2.6 ±â€¯0.2, 0.25 ±â€¯0.01, 1.07 ±â€¯0.09, and 1.90 ±â€¯0.35, respectively). CONCLUSIONS: Simvastatin therapy has beneficial effects on inflammatory markers in plasma, but CoQ10 supplementation seems to have no additional potentiating effect in patients in primary prevention. In contrast, glucose homeostasis may improve with CoQ10 supplementation.

Glucose homeostasis in statin users-The LIFESTAT study.

BACKGROUND: Statins are widely used to lower cholesterol concentrations in both primary and secondary prevention of cardiovascular disease. The treatment increases the risk of muscle pain (myalgia) and of type 2 diabetes. However, the underlying mechanisms remain disputed. METHODS: We investigated whether statin induced myalgia is coupled to impaired glucose homeostasis using oral glucose tolerance test (OGTT), intravenous glucose tolerance test (IVGTT), and the hyperinsulinemic euglycemic clamp. We performed a cross-sectional study of statin users without CVD (primary prevention) stratified into a statin myalgic (M; n = 25) and a non-myalgic (NM; n = 39) group as well as a control group (C; n = 20) consisting of non-statin users. RESULTS: A reduction in the insulin secretion rate during the OGTT was observed in the myalgic group compared with the non-myalgic group (AUC ISROGTT , C: 1032 (683 - 1500); M: 922 (678 - 1091); NM: 1089 (933 - 1391) pmol·L-1 ·min (median with 25%-75% percentiles), but no other measurements indicated impaired ß-cell function. We found no other differences between the three groups for other measurements in the OGTT, IVGTT, and euglycemic clamp. Muscle protein content of GLUT4 and hexokinase II was similar between the three groups. CONCLUSIONS: We conclude that statin users in primary prevention experiencing myalgia do not have impaired glucose homeostasis compared with other statin users or non-users. We consider this an important aspect in the dialogue between physician and patient regarding statin treatment and adverse effects.

Effect of the mineralocorticoid receptor antagonist eplerenone on liver fat and metabolism in patients with type 2 diabetes: A randomized, double-blind, placebo-controlled trial (MIRAD trial).

AIM: To investigate whether the mineralocorticoid receptor antagonist eplerenone has beneficial effects on liver fat and metabolism in patients with type 2 diabetes (T2D), the mineralocorticoid receptor antagonist in type 2 diabetes (MIRAD) trial. MATERIAL AND METHODS: In this 26-week, double-blind, randomized, placebo-controlled trial, we enrolled 140 patients with T2D and high risk of cardiovascular disease. Patients were randomized 1:1 to either eplerenone with a target dose of 200 mg/day for patients with estimated glomerular filtration rate (eGFR) of 60 mL/min per 1.73 m2 or more and 100 mg/day for patients with eGFR between 41 and 59 mL/min per 1.73 m2 or placebo. The primary outcome measure was change in liver fat by proton magnetic resonance spectroscopy at week 26 from baseline; secondary outcomes were changes in metabolism, and safety by incident hyperkalaemia. RESULTS: No changes in liver fat in the eplerenone group 0.91% (95% CI -0.57 to 2.39) or the placebo group -1.01% (-2.23 to 0.21) were found. The estimated absolute treatment difference was 1.92% (-3.81 to 0.01; P = 0.049). There was no beneficial impact on supporting secondary outcome variables of metabolism as fat mass distribution, lipid metabolism or insulin resistance. Despite a high dosage of eplerenone 164 versus 175 mg in patients treated with placebo (P = 0.228), the number of patients with incident hyperkalaemia (≥5.5 mmol/L) was low, with six in the eplerenone versus two in the placebo group (P = 0.276). CONCLUSION: The addition of high doses of eplerenone to background antidiabetic and antihypertensive therapy does not show beneficial effects on liver fat and metabolism in patients with T2D.

Trajectories of cardio-metabolic health in successful aging.

Maximal oxygen uptake (V̇O2max ) and muscle mass decrease with age. The loss of cardiorespiratory fitness and muscle strength is accelerated with physical inactivity and has well-documented consequences for morbidity and all-cause mortality. Participation in exercise training programs will improve one or more of the cardio-metabolic risk factors, but the long-term effects of such programs are questionable. Here, we re-examined 25 old (72 ± 4 years.) men and women who considered him/herself as "success-full agers" and were participants in a 3-month alpine skiing training program 6 years earlier. The program focused on healthy aging and included health questionnaires, measurement of lipids and glycemic parameters in blood and a VO2max test. Thirteen and 12 subjects were in the intervention (IG) and the control group (CG), respectively. In response to the training program, subjects improved their cardio-metabolic risk factors. However, after 6 years all positive effects had disappeared. Approximately 80% of the subjects had total cholesterol and LDL cholesterol above and HDL cholesterol below the recommended values, but these subjects remained the most metabolically deteriorated, including an increase in fasting glucose concentrations. We conclude that people seem to follow their individual trajectory in terms of cardio-metabolic risk factors, and participation in a relatively short lasting exercise training program with emphasis on healthy aging does not change that. Long-lasting change in lifestyle probably requires a continued attentional focus, goal setting, and feedback.

Determination and validation of peak fat oxidation in endurance-trained men using an upper body graded exercise test.

Peak fat oxidation rate (PFO) and the intensity that elicits PFO (Fatmax ) are commonly determined by a validated graded exercise test (GE) on a cycling ergometer with indirect calorimetry. However, for upper body exercise fat oxidation rates are not well elucidated and no protocol has been validated. Thus, our aim was to test validity and inter-method reliability for determination of PFO and Fatmax in trained men using a GE protocol applying double poling on a ski-ergometer. PFO and Fatmax were assessed during two identical GE tests (GE1 and GE2) and validated against separated short continuous exercise bouts (SCE) at 35%, 50%, and 65% of V̇O2peak on the ski-ergometer in 10 endurance-trained men (V̇O2peak : 65.1 ± 1.0 mL·min-1 ·kg-1 , mean ± SEM). Between GE tests no differences were found in PFO (GE1: 0.42 ± 0.03; GE2: 0.45 ± 0.03 g·min-1 , P = .256) or Fatmax (GE1: 41 ± 2%; GE2: 43 ± 3% of V̇O2peak , P = .457) and the intra-individual coefficient of variation (CV) was 8 ± 2% and 11 ± 2% for PFO and Fatmax , respectively. Between GE and SCE tests, PFO (GEavg : 0.44 ± 0.03; SCE; 0.47 ± 0.06 g·min-1 , P = .510) was not different, whereas a difference in Fatmax (GEavg : 42 ± 2%; SCE: 52 ± 4% of V̇O2peak , P = .030) was observed with a CV of 17 ± 4% and 15 ± 4% for PFO and Fatmax , respectively. In conclusion, GE has a high day-to-day reliability in determination of PFO and Fatmax in trained men, whereas it is unclear if PFO and Fatmax determined by GE reflect continuous exercise in general.

Aging in high functioning elderly persons: study design and analyses of behavioral and psychological factors.

This article aims to (a) describe the study design of a 6-year follow-up multidisciplinary research project on aging, (b) report the psychosocial characteristics of the sample in detail, and (c) evaluate aging-related changes of health, physical activity, and psychosocial characteristics in 10 young-old (age at pre-test: M ± SD = 63.2 ± 1.5) and 12 old-old (age at pre-test: M ± SD = 69 ± 2) individuals. Both age groups consist of individuals displaying a high health status, a high extent of physical activity, high levels of psychosocial properties in the dimensions of well-being, life satisfaction, self-concept, body image, self-esteem, and self-efficacy, as well as a low general depression index. Psychosocial characteristics demonstrated a stable pattern over a period of nearly 6 years in both age groups with the exceptions of physical activity, satisfaction with children, general depression, and self-efficacy. Furthermore, physical self-concept decreased in old-old adults, whereas the young-olds showed no change. We assume that a high psychosocial status and a physically active lifestyle play an important role for mastering aging successfully in two life phases, each of which has its own challenges for older individuals. The decline in the physical self-concept of old-olds is interpreted as a first sign of subjective aging. Its association with losses in physical performance should be addressed in future studies. Finally, aging-related changes should be monitored on an individual level in order to capture the complex dynamic of aging that is not considered in analyses of between-person differences or averages.

Copenhagen Consensus statement 2019: physical activity and ageing.

From 19th to 22nd November 2018, 26 researchers representing nine countries and a variety of academic disciplines met in Snekkersten, Denmark, to reach evidence-based consensus about physical activity and older adults. It was recognised that the term 'older adults' represents a highly heterogeneous population. It encompasses those that remain highly active and healthy throughout the life-course with a high intrinsic capacity to the very old and frail with low intrinsic capacity. The consensus is drawn from a wide range of research methodologies within epidemiology, medicine, physiology, neuroscience, psychology and sociology, recognising the strength and limitations of each of the methods. Much of the evidence presented in the statements is based on longitudinal associations from observational and randomised controlled intervention studies, as well as quantitative and qualitative social studies in relatively healthy community-dwelling older adults. Nevertheless, we also considered research with frail older adults and those with age-associated neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, and in a few cases molecular and cellular outcome measures from animal studies. The consensus statements distinguish between physical activity and exercise. Physical activity is used as an umbrella term that includes both structured and unstructured forms of leisure, transport, domestic and work-related activities. Physical activity entails body movement that increases energy expenditure relative to rest, and is often characterised in terms of intensity from light, to moderate to vigorous. Exercise is defined as a subset of structured physical activities that are more specifically designed to improve cardiorespiratory fitness, cognitive function, flexibility balance, strength and/or power. This statement presents the consensus on the effects of physical activity on older adults' fitness, health, cognitive functioning, functional capacity, engagement, motivation, psychological well-being and social inclusion. It also covers the consensus on physical activity implementation strategies. While it is recognised that adverse events can occur during exercise, the risk can be minimised by carefully choosing the type of activity undertaken and by consultation with the individual's physician when warranted, for example, when the individual is frail, has a number of co-morbidities, or has exercise-related symptoms, such as chest pain, heart arrhythmia or dizziness. The consensus was obtained through an iterative process that began with the presentation of the state-of-the-science in each domain, followed by group and plenary discussions. Ultimately, the participants reached agreement on the 30-item consensus statements.

Muscle-Saturated Bioactive Lipids Are Increased with Aging and Influenced by High-Intensity Interval Training.

Ceramide and diacylglycerol are linked to insulin resistance in rodents, but in humans the data are inconsistent. Insulin resistance is frequently observed with aging, but the role of ceramide and diacylglycerol is not clarified. Training improves metabolic health and, therefore, we aimed to elucidate the influence of age and high-intensity interval training (HIIT) on ceramide and diacylglycerol content in muscle. Fourteen young (33 ± 1) and 22 older (63 ± 1) overweight to obese subjects performed 6 weeks HIIT three times a week. Maximal oxygen uptake and body composition were measured and muscle biopsies and fasting blood samples were obtained. Muscle ceramide and diacylglycerol were measured by gas-liquid chromatography and proteins in insulin signaling, lipid and glucose metabolism were measured by Western blotting. Content of ceramide and diacylglycerol total, saturated, C16:0 and C18:0 fatty acids and C18:1 ceramide were higher in older compared to young. HIIT reduced saturated and C18:0 ceramides, while the content of the proteins involved in glucose (GLUT4, glycogen synthase, hexokinase II, AKT) and lipid metabolism (adipose triglyceride lipase, fatty acid binding protein) were increased after HIIT. We demonstrate a higher content of saturated ceramide and diacylglycerol fatty acids in the muscle of older subjects compared to young. Moreover, the content of saturated ceramides was reduced and muscle glucose metabolism improved at protein level after HIIT. This study highlights an increased content of saturated ceramides in aging which could be speculated to influence insulin sensitivity.

GIP(3-30)NH2 is an efficacious GIP receptor antagonist in humans: a randomised, double-blinded, placebo-controlled, crossover study.

AIMS/HYPOTHESIS: Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone secreted postprandially from enteroendocrine K cells, but despite therapeutically interesting effects, GIP physiology in humans remains incompletely understood. Progress in this field could be facilitated by a suitable GIP receptor antagonist. For the first time in humans, we investigated the antagonistic properties of the naturally occurring GIP(3-30)NH2 in in vivo and in in vitro receptor studies. METHODS: In transiently transfected COS-7 cells, GIP(3-30)NH2 was evaluated with homologous receptor binding and receptor activation (cAMP accumulation) studies at the glucagon-like peptide 1 (GLP-1), glucagon-like peptide-2 (GLP-2), glucagon, secretin and growth hormone-releasing hormone (GHRH) receptors. Ten healthy men (eligibility criteria: age 20-30 years, HbA1c less than 6.5% [48 mmol/mol] and fasting plasma glucose [FPG] less than 7 mmol/l) were included in the clinical study. Data were collected as plasma and serum samples from a cubital vein cannula. As primary outcome, insulin secretion and glucose requirements were evaluated together with in a randomised, four-period, crossover design by infusing GIP(3-30)NH2 (800 pmol kg-1 min-1), GIP (1.5 pmol kg-1 min-1), a combination of these or placebo during hyperglycaemic clamp experiments. The content of the infusions were blinded to the study participants and experimental personnel. No study participants dropped out. RESULTS: GIP(3-30)NH2 neither bound, stimulated nor antagonised a series of related receptors in vitro. The elimination plasma half-life of GIP(3-30)NH2 in humans was 7.6 ± 1.4 min. Markedly larger amounts of glucose were required to maintain the clamp during GIP infusion compared with the other days. GIP-induced insulin secretion was reduced by 82% (p < 0.0001) during co-infusion with GIP(3-30)NH2, and the need for glucose was reduced to placebo levels. There were no effects of GIP(3-30)NH2 alone or of GIP with or without GIP(3-30)NH2 on plasma glucagon, GLP-1, somatostatin, triacylglycerols, cholesterol, glycerol or NEFA. GIP(3-30)NH2 administration was well tolerated and without side effects. CONCLUSIONS/INTERPRETATION: We conclude that GIP(3-30)NH2 is an efficacious and specific GIP receptor antagonist in humans suitable for studies of GIP physiology and pathophysiology. TRIAL REGISTRATION: ClinicalTrials.gov registration no. NCT02747472. FUNDING: The study was funded by Gangstedfonden, the European Foundation for the Study of Diabetes, and Aase og Ejnar Danielsens fond.

Variation in mitochondrial respiratory capacity and myosin heavy chain composition in repeated muscle biopsies.

Skeletal muscle is a heterogeneous tissue and it is essential to know the methodological variation and reliability when measuring aspects of muscle function. We assessed the methodological and biological variation when measuring mitochondrial respiratory capacity (MRC), citrate synthase (CS) activity and myosin heavy chain (MHC) composition in muscle biopsies from nine healthy male participants, and in addition we assessed variation in MRC in isolated mitochondria and yeast suspension. We analysed MRC, CS activity and MHC composition in duplicates (intra-biopsy variation) to quantify the methodological variation, as well as the biological variation from multiple muscle biopsies (inter-biopsy variation) obtained at different sites of the same muscle. Three muscle biopsies (B1, B2 and B3) were obtained from each subject in m. vastus lateralis. Two of the biopsies were from the same leg and one from the other leg. For MRC, intra-biopsy coefficient of variation (CV) was 8.4% and inter-biopsy CV was 13.3%. For MHC type I, IIa and IIx intra-biopsy CV was 8.3, 6.0 and 22.3%, respectively. Inter-biopsy CV for these MHC types were 21.5, 15.4 and 42.0%, respectively. For CS activity intra-biopsy CV was 0.6% and inter-biopsy CV was 15.3%. No differences between B1, B2 and B3 were detected for MRC, CS activity or MHC composition.

Peak Fat Oxidation is not Independently Related to Ironman Performance in Women.

The aim of the present study was to investigate if peak fat oxidation rate (PFO) is related to Ironman performance in female athletes. Thirty-six female Ironman athletes (age: 34±1 yrs, [21-45 yrs.] SEM [Range]) with a BMI of 22.1±2.0 kg/m2 [18.8-28.4 kg/m2], a body fat percentage of 24.8±1.0% [9.0-37.0%] and a V̇O2peak of 53.0±1.3 ml/min/kg [36.5-70.5 ml/min/kg] were tested in the laboratory prior to the Ironman Copenhagen 2017. Race time ranged from 9:17:07 to 15:23:48 with mean race time being 11:57:26 h:min:s (717 min). By simple linear regression analyses we found associations between race time and P FO (r2=0.22, p<0.005), V̇O2peak (r2=0.65, p<0.0001) and the relative exercise intensity eliciting PFO (Fatmax) (r2=0.35, p=0.0001). Furthermore, associations were found between race time and body fat percentage (r2=0.44, p<0.0001) and age (r2=0.16, p<0.05). By means of multiple regression analysis, V̇O2peak was the only statistically significant variable explaining 64% of the variation in race time (adj. r2=0.64, p<0.005). In conclusion, these results demonstrate that PFO is not independently related to Ironman performance in a heterogeneous group of female athletes. Interestingly, V̇O2peak alone was able to predict 64% of the variation in Ironman race times.

Pre-ischaemic mitochondrial substrate constraint by inhibition of malate-aspartate shuttle preserves mitochondrial function after ischaemia-reperfusion.

KEY POINTS: Pre-ischaemic administration of aminooxiacetate (AOA), an inhibitor of the malate-aspartate shuttle (MAS), provides cardioprotection against ischaemia-reperfusion injury. The underlying mechanism remains unknown. We examined whether transient inhibition of the MAS during ischaemia and early reperfusion by AOA treatment could prevent mitochondrial damage at later reperfusion. The AOA treatment preserved mitochondrial respiratory capacity with reduced mitochondrial oxidative stress during late reperfusion to the same extent as ischaemic preconditioning (IPC). However, AOA treatment, but not IPC, reduced the myocardial interstitial concentration of tricarboxylic acid cycle intermediates at the onset of reperfusion. The results obtained in the present study demonstrate that metabolic regulation by inhibition of the MAS at the onset of reperfusion may be beneficial for the preservation of mitochondrial function during late reperfusion in an IR-injured heart. ABSTRACT: Mitochondrial dysfunction plays a central role in ischaemia-reperfusion (IR) injury. Pre-ischaemic administration of aminooxyacetate (AOA), an inhibitor of the malate-aspartate shuttle (MAS), provides cardioprotection against IR injury, although the underlying mechanism remains unknown. We hypothesized that a transient inhibition of the MAS during ischaemia and early reperfusion could preserve mitochondrial function at later phase of reperfusion in the IR-injured heart to the same extent as ischaemic preconditioning (IPC), which is a well-validated cardioprotective strategy against IR injury. In the present study, we show that pre-ischaemic administration of AOA preserved mitochondrial complex I-linked state 3 respiration and fatty acid oxidation during late reperfusion in IR-injured isolated rat hearts. AOA treatment also attenuated the excessive emission of mitochondrial reactive oxygen species during state 3 with complex I-linked substrates during late reperfusion, which was consistent with reduced oxidative damage in the IR-injured heart. As a result, AOA treatment reduced infarct size after reperfusion. These protective effects of MAS inhibition on the mitochondria were similar to those of IPC. Intriguingly, the protection of mitochondrial function by AOA treatment appears to be different from that of IPC because AOA treatment, but not IPC, downregulated myocardial tricarboxilic acid (TCA)-cycle intermediates at the onset of reperfusion. MAS inhibition thus preserved mitochondrial respiratory capacity and decreased mitochondrial oxidative stress during late reperfusion in the IR-injured heart, at least in part, via metabolic regulation of TCA cycle intermediates in the mitochondria at the onset of reperfusion.

Insulin sensitivity in relation to fat distribution and plasma adipocytokines among abusers of anabolic androgenic steroids.

OBJECTIVE: Abuse of anabolic androgenic steroids (AAS) is prevalent among young men, but information regarding effects on insulin sensitivity and fat distribution is limited. The objective was to investigate insulin sensitivity in relation to fat distribution and adipocytokines among current and former AAS abusers compared with controls. DESIGN: Cross-sectional study among men involved in recreational strength training. Current and former AAS abusers (n=37 and n=33) and controls (n=30) volunteered from the community. METHODS: We assessed insulin sensitivity by Matsuda index (oral glucose tolerance test). Using overnight fasting blood samples, adiponectin and leptin were measured. Body composition and fat distribution, including visceral adipose tissue (VAT), were assessed by dual energy X-ray absorptiometry. RESULTS: Current and former AAS abusers displayed lower Matsuda index than controls (%-difference (95%CI) from controls, -26% (-45; -1) and -39% (-55; -18)). Testosterone was markedly higher among current AAS abusers and subnormal among former AAS abusers compared with controls. Current AAS abusers displayed higher mean VAT than controls (388 (17) vs 293 (12) cm3 , P<.001) whereas body fat %, adiponectin and leptin concentrations were lower. In contrast, former AAS abusers showed highest leptin concentrations and body fat %. Multivariate linear regressions identified VAT as independent predictor of lower Matsuda index among current AAS abusers compared with controls; while body fat % independently predicted lower Matsuda index among former AAS abusers. CONCLUSIONS: Both current and former AAS abusers displayed lower insulin sensitivity which could be mediated by higher VAT and total body fat %, respectively.

Temporary impact of blood donation on physical performance and hematologic variables in women.

BACKGROUND: No former studies have examined how blood donation influences physical performance in women, who due to menstruation may have a slower recovery of performance. Therefore, the aim of this study was to clarify how VO2peak , time trial (TT) performance, and hematologic variables are affected in 18 iron-sufficient (plasma ferritin [P-ferritin] > 30 µg/L) women after a standard 450-mL blood donation. STUDY DESIGN AND METHODS: VO2peak , TT performance, and blood variables were measured at baseline and 3, 7, 14, 21, and 28 days after blood donation in 18 iron-sufficient women. Anthropometrics were measured at baseline and Day 28. RESULTS: VO2peak was reduced by 7.5 ± 1.1% from 2973 ± 87 mL/min at baseline to 2765 ± 73 mL/min 3 days after blood donation and remained below baseline until 28 days. The TT performance was reduced by 5.2 ± 1.0% from baseline (868 ± 31 sec) to Day 3 (915 ± 29 sec), but was not different from baseline 14 days after blood donation. Blood hemoglobin (B-Hb) concentration declined by 7.6 ± 2.1% from 8.4 ± 0.1 to 7.8 ± 0.1 mmol/L at baseline and on Day 3, respectively. P-ferritin at baseline was 58 ± 7 µg/L and it decreased (55 ± 3%) to a nadir of 24 ± 3 µg/L 28 days after blood donation and remained lower at 36 ± 4 µg/L after 90 days. CONCLUSION: VO2peak and B-Hb were only recovered 28 days after a blood donation whereas TT performance was back to baseline 14 days after blood donation.

The effects of 2 weeks of statin treatment on mitochondrial respiratory capacity in middle-aged males: the LIFESTAT study.

BACKGROUND: Statins are used to lower cholesterol in plasma and are one of the most used drugs in the world. Many statin users experience muscle pain, but the mechanisms are unknown at the moment. Many studies have hypothesized that mitochondrial function could be involved in these side effects. AIM: The aim of the study was to investigate mitochondrial function after 2 weeks of treatment with simvastatin (S; n = 10) or pravastatin (P; n = 10) in healthy middle-aged participants. METHODS: Mitochondrial respiratory capacity and substrate sensitivity were measured in permeabilized muscle fibers by high-resolution respirometry. Mitochondrial content (citrate synthase (CS) activity), antioxidant content, as well as coenzyme Q10 concentration (Q10) were determined. Fasting plasma glucose and insulin concentrations were measured, and whole body maximal oxygen uptake (VO2max) was determined. RESULTS: No differences were seen in mitochondrial respiratory capacity although a tendency was observed for a reduction when complex IV respiration was analyzed in both S (229 (169; 289 (95% confidence interval)) vs. 179 (146; 211) pmol/s/mg, respectively; P = 0.062) and P (214 (143; 285) vs. 162 (104; 220) pmol/s/mg, respectively; P = 0.053) after treatment. A tendency (1.64 (1.28; 2.00) vs. 1.28 (0.99; 1.58) mM, respectively; P = 0.092) for an increased mitochondrial substrate sensitivity (complex I-linked substrate; glutamate) was seen only in S after treatment. No differences were seen in Q10, CS activity, or antioxidant content after treatment. Fasting glucose and insulin as well as VO2max were not changed after treatment. CONCLUSION: Two weeks of statin (S or P) treatment have no major effect on mitochondrial function. The tendency for an increased mitochondrial substrate sensitivity after simvastatin treatment could be an early indication of the negative effects linked to statin treatment.