Aerobic Fitness and the Brain: Increased N-Acetyl-Aspartate and Choline Concentrations in Endurance-Trained Middle-Aged Adults

Engagement in regular aerobic exercise is associated with cognitive benefits, but information on the mechanisms governing these changes in humans is limited. The goal of the current study was to compare neurometabolite concentrations relating to cellular metabolism, structure, and viability in endurance-trained and sedentary middle-aged adults. Twenty-eight endurance-trained and 27 sedentary adults, aged 40–65 years, underwent general health assessment, cardiorespiratory fitness measurement, neuropsychological testing, and proton magnetic resonance spectroscopy (¹H MRS). ¹H MRS was used to examine N-acetyl-aspartate (NAA), creatine (Cr), myo-inositol (mI), choline (Cho), and glutamate (Glu) concentrations in frontal and occipitoparietal grey matter. Group differences in concentrations of NAA, Cho, mI, and Glu, calculated as ratios over Cr, were explored using ANOVA. There were no significant differences in global cognitive function, memory, and executive function performance between the groups. In comparison to sedentary adults, the endurance-trained group displayed significantly higher NAA/Cr in the frontal grey matter (F(1, 53) = 5.367, p = 0.024) and higher Cho/Cr in the occipitoparietal grey matter (F(1, 53) = 5.138, p = 0.028). Within our middle-aged sample, endurance-trained adults demonstrated higher levels of NAA/Cr in the frontal grey matter and higher Cho/Cr in the occipitoparietal grey matter. Higher levels of NAA may indicate greater neuronal integrity and higher cerebral metabolic efficiency in association with cardiorespiratory fitness, whereas increased Cho may represent increased phospholipid levels secondary to neural plasticity.     

Comparison of central artery elasticity in swimmers, runners, and the sedentary

Although swimming is one of the most popular, most practiced, and most recommended forms of physical activity, little information is available regarding the influence of regular swimming on vascular disease risks. Using a cross-sectional study design, key measurements of vascular function were performed in middle-aged and older swimmers, runners, and sedentary controls. There were no group differences in age, height, dietary intake, and fasting plasma concentrations of glucose, total cholesterol, and low-density lipoprotein cholesterol. Runners and swimmers were not different in their weekly training volume. Brachial systolic blood pressure and pulse pressure were higher (p <0.05) in swimmers than in sedentary controls and runners. Runners and swimmers had lower (p <0.05) carotid systolic blood pressure and carotid pulse pressure than sedentary controls. Carotid arterial compliance was higher (p <0.05) and β-stiffness index was lower (p <0.05) in runners and swimmers than in sedentary controls. There were no significant group differences between runners and swimmers. Cardiovagal baroreflex sensitivity was greater (p <0.05) in runners than in sedentary controls and swimmers and baroreflex sensitivity tended to be higher in swimmers than in sedentary controls (p = 0.07). Brachial artery flow-mediated dilation was significant greater (p <0.05) in runners compared with sedentary controls and swimmers. In conclusion, our present findings are consistent with the notion that habitual swimming exercise may be an effective endurance exercise for preventing loss in central arterial compliance.     

Effects of swimming training on blood pressure and vascular function in adults >50 years of age

Swimming is ideal for older adults because it includes minimum weight-bearing stress and decreased heat load. However, there is very little information available concerning the effects of regular swimming exercise on vascular risks. We determined if regular swimming exercise would decrease arterial blood pressure (BP) and improve vascular function. Forty-three otherwise healthy adults >50 years old (60 ± 2) with prehypertension or stage 1 hypertension and not on any medication were randomly assigned to 12 weeks of swimming exercise or attention time controls. Before the intervention period there were no significant differences in any of the variables between groups. Body mass, adiposity, and plasma concentrations of glucose and cholesterol did not change in either group throughout the intervention period. Casual systolic BP decreased significantly from 131 ± 3 to 122 ± 4 mm Hg in the swimming training group. Significant decreases in systolic BP were also observed in ambulatory (daytime) and central (carotid) BP measurements. Swimming exercise produced a 21% increase in carotid artery compliance (p <0.05). Flow-mediated dilation and cardiovagal baroreflex sensitivity improved after the swim training program (p <0.05). There were no significant changes in any measurements in the control group that performed gentle relaxation exercises. In conclusion, swimming exercise elicits hypotensive effects and improvements in vascular function in previously sedentary older adults.     

Aerobic fitness and cognitive function in midlife: an association mediated by plasma insulin

Insulin resistance in midlife increases the risk of dementia in late-life. In contrast, habitual aerobic exercise is an established strategy to ameliorate insulin resistance which may translate into better cognitive outcome. To determine the role of plasma insulin in mediating the relation between cardiorespiratory fitness and cognitive function, fifty-eight adults completed assessments of plasma insulin levels, maximal oxygen consumption (VO₂max), and neuropsychological test performance. Endurance-trained subjects demonstrated better cognitive outcome (total composite z-score: 0.21?±?0.08 versus ?0.26?±?0.10, P?=?0.001) and lower concentrations of plasma insulin (12.6?±?0.6 versus 21.3?±?1.5 ulU/mL, P?<?0.001) than sedentary subjects. Greater VO₂max was significantly associated with higher memory performance (β?=?0.37, P?=?0.01) and lower plasma insulin levels (β?=??0.68, P?<?0.001). The significant association between VO₂max and memory performance was abolished when the indirect effect of plasma insulin was statistically removed (β?=?0.24, P?=?0.19). Fitness-related cognitive enhancement may be mediated, at least in part, by plasma insulin levels.