Intrinsic running capacity associates with hippocampal electrophysiology and long-term potentiation in rats

Good aerobic and metabolic fitness associates with better cognitive performance and brain health. Conversely, poor metabolic health predisposes to neurodegenerative diseases. Our previous findings indicate that rats selectively bred for Low Capacity for Running (LCR) show less synaptic plasticity and more inflammation in the hippocampus and perform worse in tasks requiring flexible cognition than rats bred for High Capacity for Running (HCR). Here we aimed to determine whether hippocampal electrophysiological activity related to learning and memory would be impaired in LCR compared to HCR rats. We also studied whether an exercise intervention could even out the possible differences. We conducted in vivo recordings from the dorsal hippocampus under terminal urethane anesthesia in middle-aged sedentary males and female rats, and in females allowed to access running wheels for 6 weeks. Our results indicate stronger long-term potentiation (LTP) in the CA3-CA1 synapse in HCR than LCR rats, and in female than male rats. Compared to LCR rats, HCR rats had more dentate spikes and more gamma epochs, the occurrence of which also correlated positively with the magnitude of LTP. Voluntary running reduced the differences between female LCR and HCR rats. In conclusion, low innate fitness links to reduced hippocampal function and plasticity which can seems to improve with voluntary aerobic exercise even in middle age.

[Study on the correlation between type 2 diabetes mellitus combined with non-alcoholic steatohepatitis and aerobic exercise performance]

Objective: To study the correlation between patients with type 2 diabetes mellitus combined with nonalcoholic steatohepatitis in order to provide theoretical support for the treatment of NAFLD through aerobic exercise performance. Methods: 253 cases with T2DM combined with NAFLD were selected. 93 cases consented to undergo a liver biopsy. Among them, 74 cases with liver biopsy successfully passed the symptom-limited cardiopulmonary exercise test (CPET) and respiratory quotient (RQ)≥1.05. Patients were divided into two groups according to the NAFLD activity score (NAS) of the pathological biopsy: the non-NASH group (NAS < 4) and the NASH group (NAS≥4). The differences in general clinical and biochemical indicators and exercise parameters were compared between the two groups. The relevant factors that affect aerobic exercise performance in NAFLD patients were explored by correlation and regression analysis. Results: The peak oxygen uptake [VO2 @ peak, (17.82 ± 5.61) ml·kg(-1)·min(-1) and (23.14 ± 5.86) ml·kg(-1)·min(-1)] and anaerobic threshold [VO2 @ AT, (11.47 ± 3.12) ml·kg(-1)·min(-1) and (13.81 ± 3.53) ml·kg(-1)·min(-1)] were lower in the NASH group than those in the non-NASH group in T2DM patients, with P < 0.01, indicating a significant decrease in aerobic exercise performance in NASH patients compared to non-NASH patients. Correlation analysis showed that patients with T2DM combined with NAFLD VO2@peak was positively correlated with RQ, carbohydrate oxidation rate (%CHO), daily carbohydrate energy supply (CHO Kcal/d), high-density lipoprotein cholesterol (HDL-C), and maximal voluntary ventilation (MVV) (r 0.360, 0.334, 0.341, 0.255, 0.294, P < 0.05 or P < 0.01, respectively) and negatively correlated with NAS score, fat attenuation, liver stiffness, fat oxidation rate (%FAT), daily fat energy supply (FAT Kcal/d), aspartate aminotransferase (AST), alanine aminotransferase (ALT), body mass, and body mass index (BMI) (r -0.558, -0.411, -0.437, -0.340, -0.270, -0.288, -0.331, -0.295, -0.469, P < 0.05 or P < 0.01, respectively). VO2@AT were positively correlated with RQ, %CHO, total cholesterol (TC), and HDL-C (r 0.351, 0.247, 0.303, 0.380, P < 0.05 or P < 0.01, respectively), while it was negatively correlated with NAS score, fat attenuation, liver stiffness, %FAT, FAT (Kcal/d), ferritin (Fer), ALT, AST, body weight, and BMI (r -0.330, -0.384, -0.428, -0.270, -0.318, 0.320, -0.404, -0.416, -0.389, -0.520, P < 0.05 or P < 0.01, respectively). Stepwise multiple regression analyses revealed that BMI, RQ, and NAS scores were independent correlated factors of aerobic exercise performance. Conclusion: Hepatic inflammation and fibrosis affect the aerobic exercise performance of patients with T2DM combined with NAFLD.

Physical activity and maximal oxygen uptake in adults with Prader-Willi syndrome

BACKGROUND

Prader-Willi Syndrome (PWS) is the most common genetic syndrome causing life-threatening obesity. Strict adherence to a low-calorie diet and regular physical activity are needed to prevent weight gain. Direct measurement of maximal oxygen uptake (VO₂ max), the "gold standard" for assessing aerobic exercise capacity, has not been previously described in PWS.

OBJECTIVES

Assess aerobic capacity by direct measurement of VO₂ max in adults with PWS, and in age and BMI-matched controls (OC), and compare the results with values obtained by indirect prediction methods.

METHODS AND PATIENTS

Seventeen individuals (12 males) age: 19-35 (28.6 ± 4.9) years, BMI: 19.4-38.1 (27.8 ± 5) kg/m² with genetically confirmed PWS who exercise daily, and 32 matched OC (22 males) age: 19-36 (29.3 ± 5.2) years, BMI: 21.1-48.1 (26.3 ± 4.9) kg/m². All completed a medical questionnaire and performed strength and flexibility tests. VO₂ max was determined by measuring oxygen consumption during a graded exercise test on a treadmill.

RESULTS

VO₂ max (24.6 ± 3.4 vs 46.5 ± 12.2 ml/kg/min, p < 0.001) and ventilatory threshold (20 ± 2 and 36.2 ± 10.5 ml/kg/min, p < 0.001), maximal strength of both hands (36 ± 4 vs 91.4 ± 21.2 kg, p < 0.001), and flexibility (15.2 ± 9.5 vs 26 ± 11.1 cm, p = 0.001) were all significantly lower for PWS compared to OC. Predicted estimates and direct measurements of VO₂ max were almost identical for the OC group (p = 0.995), for the PWS group, both methods for estimating VO₂ max gave values which were significantly greater (p < 0.001) than results obtained by direct measurements.

CONCLUSIONS

Aerobic capacity, assessed by direct measurement of VO₂ max, is significantly lower in PWS adults, even in those who exercise daily, compared to OCs. Indirect estimates of VO₂ max are accurate for OC, but unreliable in PWS. Direct measurement of VO₂ should be used for designing personal training programs and in clinical studies of exercise in PWS.

Alveolar Air and O2 Uptake During Exercise in Patients With Heart Failure

BACKGROUND

Peak exercise pulmonary oxygen uptake (V̇O₂) is a primary marker of prognosis in heart failure (HF). The pathophysiology of impaired peak V̇O₂ is unclear in patients. To what extent alveolar airway function affects V̇O₂ during cardiopulmonary exercise testing (CPET) has not been fully elucidated. This study aimed to describe how changes in alveolar ventilation (V̇_A), volume (V_A), and related parameters couple with exercise V̇O₂ in HF.

METHODS AND RESULTS

A total of 35 patients with HF (left ventricular ejection fraction 20 ± 6%, age 53 ± 7 y) participated in CPET with breath-to-breath measurements of ventilation and gas exchange. At rest, 20 W, and peak exercise, arterial CO₂ tension was measured via radial arterial catheterization and used in alveolar equations to derive V̇_A and V_A. Resting lung diffusion capacity for carbon monoxide (DL_CO) was assessed and indexed to V_A for each time point. Resting R² between V̇O₂ and V̇_A, V_A, DL_CO, and DL_CO/V_A was 0.68, 0.18, 0.20, and 0.07, respectively (all P < .05 except DL_CO/V_A). 20 W R² between V̇O₂ and V̇_A, V_A, DL_CO, and DL_CO/V_A was 0.64, 0.32, 0.07, and 0.18 (all P < .05 except DL_CO). Peak exercise R² between V̇O₂ and V̇_A, V_A, DL_CO, and DL_CO/V_A was 0.55, 0.31, 0.34, and 0.06 (all P < .05 except DL_CO/V_A).

CONCLUSIONS

These data suggest that alveolar airway function that is not exclusively related to effects caused by localized lung diffusivity affects exercise V̇O₂ in moderate-to-severe HF.

Effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players

[Purpose] The study investigated the effects of lower extremity injuries on aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function in high school soccer players. [Subjects and Methods] The study assessed U High School soccer players (n=40) in S area, South Korea, divided into 2 groups: a lower extremity injury group (n=16) comprising those with knee and ankle injuries and a control group (n=24) without injury. Aerobic exercise capacity, anaerobic power, and knee isokinetic muscular function were compared and analyzed. [Results] Regarding the aerobic exercise capacity test, significant differences were observed in maximal oxygen uptake and anaerobic threshold between both groups. For the anaerobic power test, no significant difference was observed in peak power and average power between the groups; however, a significant difference in fatigue index was noted. Regarding the knee isokinetic muscular test, no significant difference was noted in knee flexion, extension, and flexion/extension ratio between both groups. [Conclusion] Lower extremity injury was associated with reduced aerobic exercise capacity and a higher fatigue index with respect to anaerobic exercise capacity. Therefore, it seems necessary to establish post-injury training programs that improve aerobic and anaerobic exercise capacity for soccer players who experience lower extremity injury.

Effects of various acute hypoxic conditions on metabolic parameters and cardiac function during exercise and recovery

Purpose

Evaluation of metabolic parameters and cardiac function is important to determine the decrease in aerobic exercise capacity under hypoxic conditions. However, the variations in metabolic parameters and cardiac function and the reasons for the decrease in aerobic exercise capacity under hypoxic conditions have not been clearly explained. The purpose of this study was to compare the responses between sea level and various acute normobaric hypoxic conditions on metabolic parameters and cardiac function during exercise and recovery in order to evaluate aerobic exercise capacity.

Methods

Ten healthy male participants (21.3 ± 3.06 y) performed submaximal bicycle exercise (116.7 ± 20.1 W and 60 rpm) at sea level (20.9 % O₂) and under various normobaric hypoxic conditions (16.5 % O₂, 14.5 % O₂, 12.8 % O₂, and 11.2 % O₂) in a random order. Metabolic parameters (arterial oxygen saturation; S_PO₂, oxygen consumption; VO₂, blood lactate level) and cardiac function (heart rate; HR, stroke volume; SV, end-systolic volume; ESV, end-diastolic volume; EDV, ejection fraction; EF, cardiac output; CO) were measured at rest, during exercise (30 min), and recovery (30 min). We compared the responses on metabolic parameters and cardiac function between the different oxygen partial pressure conditions during exercise and recovery.

Results

The various acute normobaric hypoxic conditions did not affect VO₂ and SV during exercise and recovery. S_PO₂ decreased (p < .05) and blood lactate level increased (p < .05) as the oxygen partial pressure decreased. HR, EF, CO increased (p < .05) and EDV, ESV decreased (p < .05) at oxygen partial pressures of 14.5 % O₂ and below compared with 20.9 and 16.5 % O₂ during exercise and recovery.

Conclusion

A decrease in the oxygen partial pressure to 14.5 % O₂ and below might be associated with significant changes in metabolic parameters and cardiac function during exercise and recovery. These changes are an acute compensation response to reduced aerobic exercise capacity by decreased oxygen delivering and utilizing capacities under hypoxic conditions.