Affective Modulation after High-Intensity Exercise Is Associated with Prolonged Amygdalar-Insular Functional Connectivity Increase.

Acute moderate exercise has been shown to induce prolonged changes in functional connectivity (FC) within affect and reward networks. The influence of different exercise intensities on FC has not yet been explored. Twenty-five male athletes underwent 30 min of "low"- (35% < lactate threshold (LT)) and "high"- (20% > LT) intensity exercise bouts on a treadmill. Resting-state fMRI was acquired at 3 Tesla before and after exercise, together with the Positive and Negative Affect Scale (PANAS). Data of 22 subjects (3 dropouts) were analyzed using the FSL feat pipeline and a seed-to-network-based analysis with the bilateral amygdala as the seed region for determining associated FC changes in the "emotional brain." Data were analyzed using a repeated measures ANOVA. Comparisons between pre- and post-exercise were analyzed using a one-sample t-test, and a paired t-test was used for the comparison between "low" and "high" exercise conditions (nonparametric randomization approach, results reported at p < 0.05). Both exercise interventions induced significant increases in the PANAS positive affect scale. There was a significant interaction effect of amygdalar FC to the right anterior insula, and this amygdalar-insular FC correlated significantly with the PANAS positive affect scale (r = 0.47, p = 0.048) in the "high"-intensity exercise condition. Our findings suggest that mood changes after exercise are associated with prolonged alterations in amygdalar-insular FC and occur in an exercise intensity-dependent manner.

Acute BDNF and cortisol response to low intensity exercise and following ramp incremental exercise to exhaustion in humans.

The effect of short-term aerobic exercise and a following ramp incremental cycle ergometry to exhaustion on the acute response of the serum concentrations of brain derived neurotrophic factor (BDNF) and cortisol (COR) was examined in 8 healthy male athletes. Venous and capillary blood samples were drawn at rest, immediately after a 10 min warm-up period with aerobic exercise and after a ramp test to exhaustion, as well as 3, 6, 10 and 15 min post exercise. Capillary blood lactate (LA) concentration and blood gases as well as serum BDNF and COR concentrations did not change during the warm-up period. LA was increased (p<0.05) at the end of the ramp test and during recovery period while bicarbonate concentration, carbon dioxide pressure, pH and base excess were decreased (p<0.05) during this period. Serum BDNF was increased at the point of exhaustion (p<0.05) while no significant differences were found between values at rest and those during recovery period. At 10 and 15 min post incremental exercise, COR concentrations were increased (p<0.05) compared to rest. The present study is the first to demonstrate in humans that in contrast to short duration aerobic exercise immediately after a following short duration high-intensity exercise to exhaustion, there is a transient augmentation of serum BDNF concentration. Short-term response of serum BDNF and COR concentrations differs as BDNF returns to baseline level faster than COR.

Bicarbonate reduces serum prolactin increase induced by exercise to exhaustion.

PURPOSE: The aim of the study was to examine the effect of acid-base status on serum prolactin (PRL) concentration postexercise. METHODS: Seven male recreational athletes participated in two experimental trials separated by 1 wk. In the respective trial, subjects received either a placebo infusion (normal isotonic saline) or an alkali infusion (isotonic sodium bicarbonate) before and during exercise. Venous and capillary blood samples were drawn at rest, immediately after a 10-min warm-up period, and after a maximal ramp test on a cycle ergometer, as well as at 3, 6, 10, and 15 min postexercise. RESULTS: Power output, HR, capillary blood lactate concentration, carbon dioxide pressure (PCO2), and partial oxygen pressure (PO2) did not differ between trials at any point in time. Capillary PO2 did not change from resting values, but a significant increase (P < 0.05) was found from the end of warm-up to 3 min of the recovery period. Exercise induced a significant (P < 0.01) decrease in capillary blood bicarbonate concentration (HCO3-), pH, base excess (BE), and PCO2 at exhaustion and during the recovery period. Significantly higher HCO3-, pH, and BE were found during bicarbonate infusion and postexercise in comparison with the placebo trial. Serum PRL concentration was significantly increased 3 min postexercise until the end of the placebo trial, whereas after bicarbonate infusion, serum PRL concentration did not change from values at rest. Significant (P < 0.01) differences between trials in serum PRL concentration were found 10 and 15 min postexercise. CONCLUSIONS: The present study suggests that acidosis is a stimulus for exercise-induced PRL secretion.

Energy expenditure in wheelchair racing and handbiking - a basis for prevention of cardiovascular diseases in those with disabilities.

OBJECTIVE: Handbiking and wheelchair racing have gained increased popularity in Germany. This is important because of the inability of wheelchair-dependent people to maintain cardiovascular health and fitness through daily activities. The purpose of this study was to evaluate the energy expenditure (EE; kcal/h) of wheelchair-dependent individuals. METHODS: Ten wheelchair racers (WR) and 17 handbikers (HB) completed a basal metabolism evaluation, an incremental exercise test until exhaustion and an endurance test. Oxygen uptake and carbon dioxide production ([V(. -)]O(2), [V(. -)]CO(2); ml/min), arterialized capillary blood lactate concentration (LA; mmol/l) and heart rate (HR; bpm) were recorded during each test. EE was calculated by indirect calorimetry. RESULTS: In the endurance test [V(. -)]O(2), [V(. -)]CO(2), LA, HR and EE at an intensity corresponding to 2 mmol/l lactate were: HB: 1332+/-368 ml/min, 1178+/-303 ml/min, 2.23+/-0.85 mmol/l, 116.8+/-19.1 bpm, 389.6+/-105.4 kcal/h; WR:1175+/-285 ml/min, 1145+/-258 ml/min, 2.65+/-0.36 mmol/l, 142.5+/-28.0 bpm, 341.7+/-84.0 kcal/h. At an intensity corresponding to 4 mmol/l lactate the values were: HB: 1792+/-408 ml/min, 1666+/-326 ml/min, 4.27+/-1.40 mmol/l 146.1+/-22.8 bpm, 530.1+/- 115.4 kcal/h; WR: 1505+/-210 ml/min, 1427+/-188 ml/min, 3.31+/-1.0 mmol/l, 165.3+/-22.7 bpm, 445.5+/-70.8 kcal/h. CONCLUSION: The results show that EE of HB and WR is high enough to maintain fitness and probably to help to prevent cardiovascular diseases even at a moderate intensity.