Repeated Prolonged Exercise Decreases Maximal Fat Oxidation in Older Men

Effect of Moderate-Intense Training and Detraining on Glucose Metabolism, Lipid Profile, and Liver Enzymes in Male Wistar Rats: A Preclinical Randomized Study

Exercise training positively regulates glucose metabolism. This study investigated the impact of training and detraining on glucose metabolism, lipid profiles, and liver enzymes. Twenty-six rats completed an initial 4-week moderate-intense training (T0-T4). Then, the animals were randomly assigned to two groups at the end of week 4: AT4: detraining for 8 weeks; AT8: training for 8 weeks and 4-week detraining. Six animals were sacrificed at T0 and T4, four animals/group at T8, and three/group at T12. The study continued for 12 weeks, and all parameters were assessed at T0, T4, T8, and T12. IPGTT significantly improved after 4 weeks of training (p < 0.01) and was further reduced in AT8 at T8. In AT8, 8-week training significantly reduced total cholesterol at T4 and T12 vs. T0 (p < 0.05), LDL at T4, T8, and T12 vs. T0 (p < 0.01), ALP at T8, T12 vs. T0 (p < 0.01), and increased HDL at T8 and ALT at T8 and T12 vs. T0 (p < 0.05). Triglycerides and hexokinase activity increased significantly at T4 and T8 (p < 0.05) and then decreased at T12 in AT8. Pyruvate and glycogen increased at T12 in AT8 vs. AT4. Eight-week training improved LPL and ATGL expressions. Training positively modulated insulin, glucose metabolism, and lipid profiles, but detraining reduced the benefits associated with the initial training.

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. V̇O₂max 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.

Impact of Polarized Versus Threshold Training on Fat Metabolism and Neuromuscular Variables in Ultrarunners

PURPOSE

To compare the effects of 2 different intensity distribution training programs (threshold [THR] and polarized [POL]) on fat metabolism and neuromuscular variables.

METHODS

Twenty ultrarunners were allocated to POL (n = 11; age 40.6 [9.7] y, weight 73.5 [10.8] kg, VO2max 55.8 [4.9] mL·kg-1·min-1) or THR group (n = 9; age 36.8 [9.2] y, weight 75.5 [10.4] kg, VO2max 57.1 [5.2] mL·kg-1·min-1) and performed a 12-week training program that consisted of 5 running sessions, 2 strength sessions, and 1 day of full rest per week. Both groups performed similar total training duration and load but with different intensity distribution during running sessions. Resting metabolic rate, fat metabolism, isometric rate of force development (RFD; N·s-1) and maximal voluntary contraction in the knee extensor, and electromyographic amplitude were measured before and after each program.

RESULTS

A significant decrease in RFD0-100 ms (Δ -13.4%; P ≤ .001; effect size [ES] = 1.00), RFD0-200 ms (Δ -11.7%; P ≤ .001; ES = 1.4), and RFDpeak (Δ -18%; P ≤ .001; ES = 1.4) were observed in the POL group. In THR group, a significant increase in mean electromyographic amplitude (Δ 24.4%; P = .02; ES = 1.4) was observed. There were no significant differences between groups in any of the variables.

CONCLUSIONS

Similar adaptations in fat metabolism and neuromuscular performance can be achieved after 12 weeks of POL or THR intensity distribution. However, THR distribution appears to better maintain strength (RFD) and improve mean electromyographic amplitude. Nevertheless, the combination of both running and maximum strength training could influence on results because of the residual fatigue thus inducing suboptimal adaptations in the POL group.

2706 km cycling in 2 weeks: effects on cardiac function in 6 elderly male athletes

OBJECTIVES

Physiological effects of exercise on trained and untrained individuals have been studied extensively. Typically, young or middle-aged individuals are examined before and after short periods of vigorous exertion.

METHODS

We studied 6 elderly male athletes (61 ± 8 years (mean ± SD); baseline [Formula: see text]O₂max 48 ± 5 ml·kg^-1·min^-1) with focus on cardiac function and biomarkers following 14 consecutive days of moderate intensity exercise. Cardiac dimensions, function, biomarkers, and other measures of cardiovascular health were examined at baseline and 2 and 28 h after the last day of cycling a total of 2706 km.

RESULTS

Data collected after the cessation of exercise on the 14th day revealed significant increases in average size of the left atrium (3.5 ± 0.4 to 4.0 ± 0.3 cm; p = 0.02) and left ventricular end systolic volume (47 ± 2 to 52 ± 5 ml; p = 0.004), with no other significant changes in cardiac size or function. Small, transient increases in cardiac biomarkers (troponin T, creatine kinase myocardial band, and N-terminal pro-brain natriuretic peptide) (p < 0.01) were observed 2 h after completion of cycling but no changes in systolic (including strain-analyses) or diastolic cardiac function were observed at rest. [Formula: see text]O₂max was significantly lower at the 28 h time point than at baseline (p < 0.02). Plasma concentrations of total- (p < 0.01) and low-density lipoprotein-cholesterol (p < 0.01) were markedly lower after exercise. Systolic blood pressure was unchanged, but diastolic pressure was significantly lower after exercise than at baseline.

CONCLUSIONS

The results suggest that repeated moderate intensity exercise in elderly men was associated with a transient increase in cardiac biomarkers while cardiac function remained unaltered. A favorable reduction in blood lipids and diastolic blood pressure were seen for >28 h after the end of activity. An unexplained symptomless severe plasma hyponatremia developed in 3 of 6 subjects 28 h after the end of activity.

Repeated Excessive Exercise Attenuates the Anti-Inflammatory Effects of Exercise in Older Men

Introduction/Purpose: A number of studies have investigated the effect of training with a moderate exercise dose (3-6 h/weekly) on the inflammatory profile in blood, and the data are inconsistent. Cross-sectional studies indicate a positive effect of physical activity level on inflammation levels and risk of metabolic disease. However, it is not clear whether this may be dose dependent and if very prolonged repeated exercise therefore may be beneficial for low-grade inflammation. Based on this we studied how excessive repeated prolonged exercise influenced low-grade inflammation and adipose tissue anti-inflammatory macrophage content in six older male recreationally trained cyclists. Low-grade inflammation and adipose tissue macrophage content were investigated in six older trained men (age: 61 ± 4 years; VO_2peak: 48 ± 2 mL kg^-1 min^-1) following repeated prolonged exercise. Methods: Cycling was performed daily for 14 days covering in total 2,706 km (1,681 miles). Maximal oxygen uptake (VO_2peak) was measured before and after the cycling. Duration and intensity of the exercise were determined from heart rates sampled during cycling. An adipose tissue biopsy from subcutaneous abdominal fat and a blood sample were obtained at rest in the overnight fasted state before and after the cycling. Anti-inflammatory adipose tissue macrophages (ATM) were immunohistochemically stained in cross sectional sections using a CD163 binding antibody. The ATM and adipocyte sizes were analyzed blindly. Results: The cyclists exercised daily for 10 h and 31 ± 37 min and average intensity was 53 ± 1% of VO_2peak. Body weight remained unchanged and VO_2peak decreased by 6 ± 2% (P = 0.04). Plasma inflammatory cytokines, TNFα and IL-18 remained unchanged, as did hsCRP, but plasma IL-6 increased significantly. CD163 macrophage content remained unchanged, as did adipocyte cell size. The HbA1c was not significantly decreased, but there was a trend (P < 0.07) toward an increased insulin resistance as estimated by the Quicki Index. Conclusion: The regular prolonged exercise did not influence abdominal adipose tissue inflammation, but the higher plasma IL-6 concentration concurrent with a trend toward higher insulin resistance and decreased VO_2peak implies that the excessive amount of exercise probably attenuated the possible potential anti-inflammatory effects of exercise.