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.

Prolonged Endurance Exercise Increases Macrophage Content and Mitochondrial Respiration in Adipose Tissue in Trained Men.

BACKGROUND: The aim of this study was to investigate the effect of prolonged endurance exercise on adipose tissue inflammation markers and mitochondrial respiration in younger and older men. METHODS: "Young" (aged 30 years, n = 7) and "old" (aged 65 years, n = 7) trained men were exposed to an exercise intervention of 15 consecutive days biking 7 to 9 hours/day at 63% and 65% of maximal heart rate (young and old, respectively), going from Copenhagen, Denmark to Palermo, Italy. Adipose tissue was sampled from both the gluteal and abdominal depot before and after the intervention. Mitochondrial respiration was measured by high-resolution respirometry, and adipose inflammation was assessed by immunohistochemical staining of paraffin embedded sections. RESULTS: An increased number of CD163+ macrophages was observed in both the gluteal and abdominal depot (P < .01). In addition, an increased mitochondrial respiration was observed in the abdominal adipose tissue from men in the young group with complex I (CIp) stimulated respiration, complex I + II (CI+IIp) stimulated respiration and the capacity of the electron transport system (ETS) (P < .05), and in the older group an increase in CIp and CI+IIp stimulated respiration (P < .05) was found. CONCLUSION: Overall, we found a positive effect of prolonged endurance exercise on adipose tissue inflammation markers and mitochondrial respiration in both young and old trained men, and no sign of attenuated function in adipose tissue with age.

Extreme duration exercise affects old and younger men differently.

AIM & METHODS: Extreme endurance exercise provides a valuable research model for understanding the adaptive metabolic response of older and younger individuals to intense physical activity. Here, we compare a wide range of metabolic and physiologic parameters in two cohorts of seven trained men, age 30 ± 5 years or age 65 ± 6 years, before and after the participants travelled ≈3000 km by bicycle over 15 days. RESULTS: Over the 15-day exercise intervention, participants lost 2-3 kg fat mass with no significant change in body weight. V̇O2 max did not change in younger cyclists, but decreased (p = 0.06) in the older cohort. The resting plasma FFA concentration decreased markedly in both groups, and plasma glucose increased in the younger group. In the older cohort, plasma LDL-cholesterol and plasma triglyceride decreased. In skeletal muscle, fat transporters CD36 and FABPm remained unchanged. The glucose handling proteins GLUT4 and SNAP23 increased in both groups. Mitochondrial ROS production decreased in both groups, and ADP sensitivity increased in skeletal muscle in the older but not in the younger cohort. CONCLUSION: In summary, these data suggest that older but not younger individuals experience a negative adaptive response affecting cardiovascular function in response to extreme endurance exercise, while a positive response to the same exercise intervention is observed in peripheral tissues in younger and older men. The results also suggest that the adaptive thresholds differ in younger and old men, and this difference primarily affects central cardiovascular functions in older men after extreme endurance exercise.

Reliability and variation in mitochondrial respiration in human adipose tissue.

Adipose tissue mitochondrial function is gaining increasing interest since it is a good marker of overall health. Methodological challenges and variability in assessing mitochondrial respiration in fresh adipose tissue with high-resolution respirometry are unknown and should be explored. Mitochondrial respiratory capacity (MRC) in human adipose tissue declines in a gradual manner when analyses are postponed 3 h and 24 h, with a statistically significant decline 24 h after obtaining the biopsy. This decline in MRC is associated with a reduced integrity of the outer mitochondrial membrane at both time points. This study suggests that the optimal amount of tissue to be used is 20 mg and that different technicians handling the biopsy do not affect MRC.

Maximal Fat Oxidation Rate Is Higher in Fit Women and Unfit Women With Obesity, Compared to Normal-weight Unfit Women.

CONTEXT: The maximal fat oxidation rate (MFO) is higher in aerobically fit vs unfit young men, but this training-related increase in MFO is attenuated in middle-aged men. Further, it has also been found that unfit men with obesity may have an elevated MFO compared to unfit normal-weight men. OBJECTIVE: Based hereupon, we aimed to investigate whether a fitness-related higher MFO were attenuated in middle-aged women compared to young women. Also, we aimed to investigate if unfit women with obesity have a higher MFO compared to unfit normal-weight women. We hypothesized that the training-related elevated MFO was attenuated in middle-aged women, but that unfit women with obesity would have an elevated MFO compared to unfit normal-weight women. METHODS: We recruited 70 women stratified into 6 groups: young fit (n = 12), young unfit (n = 12) middle-aged fit (n = 12), middle-aged unfit (n = 12), unfit young women with obesity (n = 12), and unfit middle-aged women with obesity (n = 10). Body composition and resting blood samples were obtained and MFO was measured by a graded exercise test on a cycle ergometer via indirect calorimetry. Subsequently, a maximal exercise test was performed to establish peak oxygen uptake (V̇O2peak). RESULTS: Young and middle-aged fit women had a higher MFO compared to age-matched unfit women, and young fit women had a higher MFO compared to fit middle-aged women. Unfit women with obesity, independent of age, had a higher MFO compared to their normal-weight and unfit counterparts. CONCLUSION: The training-related increase in MFO seems maintained in middle-aged women, and we find that unfit women with obesity, independent of age, have a higher MFO compared to unfit normal-weight women.

Aerobic Exercise Performance and Muscle Strength in Statin Users-The LIFESTAT Study.

INTRODUCTION: Statins are widely used in both primary and secondary prevention of cardiovascular disease. The treatment increases the risk of muscle pain (myalgia) which can affect muscle function and levels of physical activity. We investigated whether statin-associated myalgia is coupled to impaired aerobic exercise performance including fat oxidation as well as impaired muscle strength. METHODS: A population-based survey (6000 people) was performed to assess the prevalence of statin-associated myalgia in the Danish population. In addition, 64 statin users in primary prevention with myalgia (M; n = 25; 61 ± 1 yr) or without myalgia (NM; n = 37; 63 ± 1 yr) as well as a control group not taking statins (C; n = 20; 60 ± 2 yr) were enrolled in a cross-sectional study where they performed aerobic exercise and muscle strength tests. RESULTS: The response rate for the survey was 51% and data showed a prevalence of statin-associated myalgia in 19% of responders using statins. The experimental study showed no difference between the groups in aerobic capacity (C, 29 ± 1 mL O2·min·kg; M, 27 ± 1 mL O2·min·kg; NM, 28 ± 1 mL O2·min·kg) or maximal fat oxidation (C, 247 ± 26 mg·min; M, 295 ± 24 mg·min; NM, 279 ± 17 mg·min). Measurements of strength were similar in all three groups including rate of force development (C, 795 ± 56 N·m·s; M, 930 ± 93 N·m·s; NM, 971 ± 57 N·m·s) and leg extension power (C: 2.6 ± 0.2; M: 2.3 ± 0.1; NM: 2.4 ± 0.1 W·kg). All results are mean ± SEM. CONCLUSION: Statin users in primary prevention experiencing myalgia do not have impaired aerobic exercise performance or muscle strength compared to nonmyalgic statin users or control subjects.

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.