ECSS Paris 2023: OP-MH05
INTRODUCTION: Peak fat oxidation (PFO) is one parameter contributing to metabolic flexibility and may therefore impact metabolic health. However, it remains unclear how obesity affects PFO. In addition, there is a lack of data on the obese elderly population and how the interplay of aging and obesity affect PFO. Here, we hypothesized that peak fat oxidation would be higher in obese compared to lean individuals, independent of age. METHODS: Healthy males matched for physical activity level were recruited into four groups; Lean young (LY) BMI 23 ± 2 aged 26 ± 5 years VO2max 3988 ± 704 ml/min (n = 12); Lean old (LO) BMI 24 ± 1 aged 65 ± 4 years VO2max 3514 ± 451 ml/min (n = 10); Obese young (OY) BMI 34 ± 3 aged 30 ± 5 years VO2max 4206 ± 675 ml/min (n = 10); Obese old (OO) BMI 33 ± 3 aged 65 ± 5 years VO2max 2998 ± 379 ml/min (n = 8). Subjects arrived overnight fasted and body composition (Dual-Energy X-Ray Absorptiometry), blood-pressure, blood sampling and hip-waist ratio were measured. After this a submaximal and maximal incremental exercise test to measure PFO and maximal oxygen consumption (VO2max) were performed. Lastly, isometric handgrip strength was tested. Data were tested for normality using Shapiro-Wilk test and Q-Q plots. Data are presented as mean ± SD. Between-group differences were analyzed using two-way ANOVA with BMI (Lean/Obese) and Age (Young/Old) as independent factors, and post-hoc comparisons conducted using Tukey’s multiple comparison test where appropriate (GraphPad Prism 10). RESULTS: BMI influenced fat oxidation at rest (P = 0.003), with higher fat oxidation observed in OY and OO compared to LY. However, fat oxidation at rest did not differ between LY and LO. PFO (LY: 0.44 ± 0.11; OY: 0.58 ± 0.24; LO: 0.57 ± 0.23; OO: 0.49 ± 0.12 g/min) and PFO/Lean body mass (LY: 7.0 ± 1.3; OY: 7.2 ± 3.0; LO: 8.6 ± 4.9; OO: 8.5 ± 2.3 mg/min/kg LBM) were similar in all groups (P > 0.05). FATmax, the percentage of VO2max eliciting PFO, was higher in the old groups compared to the LY group (P < 0.05). VO2max was lower in OO compared to LY and OY (P > 0.05). There were no differences in VO2max between the other groups. Plasma free fatty acids (FFA) were not different between groups (LY: 432 ± 228; OY: 512 ± 222; LO: 542 ± 182; OO: 628 ± 349 µmol/L). CONCLUSION: In conclusion fat oxidation at rest is higher in obese compared to young lean males regardless of age. However, in contrast to our hypothesis PFO is not affected by aging or obesity when matched for habitual physical activity level, but the intensity eliciting PFO is higher in old compared to lean young males independent of BMI. These findings contribute to our understanding of the interplay between obesity, aging and fat oxidation.
Read CV Cecilie WeinreichECSS Paris 2023: OP-MH05
INTRODUCTION: The rising prevalence of obesity-associated kidney injury is concerning, but the full extent of the injury and its underlying mechanisms are not yet fully elucidated. This study investigates the impact of varying aerobic exercise regimens on renal dysfunction in obese rats and examines the regulatory role of aerobic exercise in mitophagy. METHODS: Ninety male SD rats were divided into a normal diet group (CON, n=10) and a high-fat diet group (n=80). The high-fat diet group was fed for 8 weeks to induce obesity and renal function abnormality. After modeling, 40 rats were assigned to four groups: a high-fat diet control group (HFD, n=10) and three exercise groups (40%, 60%, and 80% VO₂max, n=10 each). Aerobic exercise was performed via treadmill training (60 min/day, 5 days/week) for 8 weeks. Post-intervention, body weight, body length, fat weights, and Lees index were measured. Blood and urine samples were collected to assess lipid profiles, serum creatinine, urinary protein, and microalbumin (mALB). Kidney pathology was examined by HE staining, and ultrastructural changes were observed using transmission electron microscopy. Western blot analysis was conducted to detect key mitophagy proteins (Beclin1 and Parkin) in kidney tissues. RESULTS: After 8 weeks of intervention, the HFD group exhibited significantly higher body weight and Lees index compared to the CON group (P<0.05), whereas these parameters in all exercise groups were significantly lower than those in the HFD group (P<0.05). The average SCr and mALB levels in the HFD group were significantly higher compared to the CON group (P<0.05). Moreover, the average SCr levels in all exercise groups were significantly lower than those in the HFD group (P<0.05), and the average mALB levels in the 40% VO₂max and 60% VO₂max groups were also significantly lower than those in the HFD group (P<0.05). The renal tubular epithelial cells in the HFD group showed moderate degeneration. In contrast, the degree of glomerular hypertrophy in each exercise group was reduced compared to the HFD group, and the renal tubules of the 60% VO₂max group showed a clearer contour. Moreover, compared with the CON group, the number of swollen mitochondria in the HFD group was increased, whereas the 60% VO₂max group exhibited a significant improvement compared with the HFD group. The protein expression levels of Beclin1 and Parkin were increased in the HFD group compared to those in the CON group (P<0.05), and a reduction was observed in the 40% VO₂max group compared with the HFD group (P<0.05). CONCLUSION: Moderate to low intensity aerobic exercise can alleviate renal dysfunction in obese rats by reducing mitophagy in renal mitochondria, as evidenced by the downregulation of renal function biochemical indicators and the reduced degree of renal tissue damage.
Read CV Bin ZhangECSS Paris 2023: OP-MH05
INTRODUCTION: Given the lack of pharmacological interventions, exercise remains a critical strategy for managing non-alcoholic fatty liver disease (NAFLD), with its efficacy well-established. Different exercise modalities induce distinct physiological stress profiles, potentially exerting differential effects on NAFLD. As NAFLD is considered a hepatic manifestation of systemic metabolic dysregulation, this study comprehensively compared the therapeutic effects of moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), and resistance training (RT) on NAFLD across multiple metabolic dimensions: liver fat, glucose metabolism, lipid metabolism, and central obesity. METHODS: Thirty-six adults with NAFLD (age: 51±8 years) were randomized to three 8-week supervised exercise regimens: MICT (3 sessions/week, 60 minutes/session at 60-70% HRmax), HIIT (3 sessions/week, 3 sets/session alternating 4-minute intervals at 85% HRmax and 4-minute recovery at 60% HRmax), or RT (3 sessions/week, 8 exercises at 60% 1RM, 3 sets × 12 repetitions). Liver fat content was measured using MRI-PDFF, insulin resistance was assessed using HOMA-IR, insulin sensitivity was assessed using the QUICKI index, and the degree of central obesity was assessed using waist circumference. RESULTS: After 8 weeks, both MICT (−2.13%; 95% CI, −3.23 to −1.02; p < 0.01) and HIIT (−1.74%; 95% CI, −3.00 to −0.48; p < 0.01) significantly reduced liver fat, with no difference between the two (P = 0.64). MICT also lowered fasting insulin levels (−3.47 μU/mL; 95% CI, −6.22 to −0.72; p = 0.02) and improved insulin sensitivity (QUICKI: +0.01; 95% CI, 0.002–0.02; p = 0.02). Waist circumference decreased in both MICT (−5.46 cm; 95% CI, −8.18 to −2.74; p < 0.01) and RT (−3.25 cm; 95% CI, −6.07 to −0.43; p = 0.02), with MICT showing a greater reduction than HIIT (p = 0.02). HIIT increased HDL cholesterol (+0.118 mmol/L; 95% CI, 0.02–0.22; p = 0.03). CONCLUSION: MICT was the most effective exercise modality for NAFLD management, achieving simultaneous improvements in hepatic steatosis, insulin resistance, and central obesity. While HIIT reduced liver fat comparably, it exhibited limitations in addressing glucose metabolism and central obesity. RT showed no direct therapeutic effect on NAFLD pathology.
Read CV Xueying HeECSS Paris 2023: OP-MH05