The effects of acute exercise on cognitive performance: a meta-analysis.

Effects of acute bouts of exercise on cognition.

Cellular hypoxia is the common final pathway of brain injury that occurs not just after asphyxia, but also when cerebral perfusion is impaired directly (eg, embolic stroke) or indirectly (eg, raised intracranial pressure after head injury). We Review recent advances in the understanding of neurological clinical syndromes that occur on exposure to high altitudes, including high altitude headache (HAH), acute mountain sickness (AMS), and high altitude cerebral oedema (HACE), and the genetics, molecular mechanisms, and physiology that underpin them. We also present the vasogenic and cytotoxic bases for HACE and explore venous hypertension as a possible contributory factor. Although the factors that control susceptibility to HACE are poorly understood, the effects of exposure to altitude (and thus hypobaric hypoxia) might provide a reproducible model for the study of cerebral cellular hypoxia in healthy individuals. The effects of hypobaric hypoxia might also provide new insights into the understanding of hypoxia in the clinical setting.

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474-4422(09)70014-6.pdf

The cerebral effects of ascent to high altitudes

Differential effects of differing intensities of acute exercise on speed and accuracy of cognition: A meta-analytical investigation

During exercise: the Kety-Schmidt-determined cerebral blood flow (CBF) does not change because the jugular vein is collapsed in the upright position. In contrast, when CBF is evaluated by 133Xe clearance, by flow in the internal carotid artery, or by flow velocity in basal cerebral arteries, a ∼25% increase is detected with a parallel increase in metabolism. During activation, an increase in cerebral O2 supply is required because there is no capillary recruitment within the brain and increased metabolism becomes dependent on an enhanced gradient for oxygen diffusion. During maximal whole body exercise, however, cerebral oxygenation decreases because of eventual arterial desaturation and marked hyperventilation-related hypocapnia of consequence for CBF. Reduced cerebral oxygenation affects recruitment of motor units, and supplemental O2 enhances cerebral oxygenation and work capacity without effects on muscle oxygenation. Also, the work of breathing and the increasing temperature of the brain during exerci...

Cerebral blood flow and metabolism during exercise: implications for fatigue

The effects of submaximal and maximal exercise on cerebral perfusion were assessed using a portable, recumbent cycle ergometer in nine unacclimatized subjects ascending to 5,260 m. At 150 m, mean (SD) cerebral oxygenation (rSO2%) increased during submaximal exercise from 68.4 (SD 2.1) to 70.9 (SD 3.8) (P < 0.0001) and at maximal oxygen uptake (.VO2(max)) to 69.8 (SD 3.1) (P < 0.02). In contrast, at each of the high altitudes studied, rSO2 was reduced during submaximal exercise from 66.2 (SD 2.5) to 62.6 (SD 2.1) at 3,610 m (P < 0.0001), 63.0 (SD 2.1) to 58.9 (SD 2.1) at 4,750 m (P < 0.0001), and 62.4 (SD 3.6) to 61.2 (SD 3.9) at 5,260 m (P < 0.01), and at .VO2(max) to 61.2 (SD 3.3) at 3,610 m (P < 0.0001), to 59.4 (SD 2.6) at 4,750 m (P < 0.0001), and to 58.0 (SD 3.0) at 5,260 m (P < 0.0001). Cerebrovascular resistance tended to fall during submaximal exercise (P = not significant) and rise at .VO2(max), following the changes in arterial oxygen saturation and end-tidal CO(2). Cerebral oxygen delivery was maintained during submaximal exercise at 150 m with a nonsignificant fall at .VO2(max), but at high altitude peaked at 30% of .VO2(max) and then fell progressively at higher levels of exercise. The fall in rSO2 and oxygen delivery during exercise may limit exercise at altitude and is likely to contribute to the problems of acute mountain sickness and high-altitude cerebral edema.

/pdf/effect-of-exercise-on-cerebral-perfusion-in-humans-at-high-1vpny8ce3g.pdf

Effect of exercise on cerebral perfusion in humans at high altitude

The main aim of this study was to compare the decision-making performance of college soccer players on a soccer-specific, tachistoscopically presented test, at rest and while exercising at their adrenaline threshold and at their maximum power output. These were determined following an incremental test to exhaustion on a cycle ergometer. After the initial maximum power test, participants (n= 9) were allowed 10 habituation trials on the soccer decision-making test. Participants' decision-making performance was tested at rest, while cycling at a power output that had previously been determined to elicit their adrenaline threshold and while cycling at maximum power output. Accuracy and speed of decision were the dependent variables. A one-way repeated measures analysis of variance showed no significant effect of exercise on accuracy, and showed speed of decision to be significantly affected by exercise. Tukey post-hoc tests showed that speed of decision at rest was significantly slower than in the other two c...

Exercise, plasma catecholamine concentrations and decision-making performance of soccer players on a soccer-specific test.

The purpose of this study was to assess the valid- ity and reliability of the Wattbike cycle ergometer against the SRM Powermeter using a dynamic cal- ibration rig (CALRIG) and trained and untrained human participants. Using the CALRIG power outputs of 50 - 1 250 W were assessed at cadences of 70 and 90 rev.min − 1 . Validity and reliability data were also obtained from 3 repeated trials in both trained and untrained populations. 4 work rates were used during each trial ranging from 50 - 300 W. CALRIG data demonstrated signifi cant diff erences ( P < 0.05) between SRM and Wattbike across the work rates at both cadences. Signifi - cant diff erences existed in recorded power out- puts from the SRM and Wattbike during steady state trials (power outputs 50 - 300 W) in both human populations (156 ± 72 W vs. 153 ± 64 W for SRM and Wattbike respectively; P < 0.05). The reliability (CV) of the Wattbike in the untrained population was 6.7 % (95 % CI 4.8 - 13.2 % ) com- pared to 2.2 % with the SRM (95 % CI 1.5 - 4.1 % ). In the trained population the Wattbike CV was 2.6 % (95 % CI 1.8 - 5.1 % ) compared to 1.1 % with the SRM (95 % CI 0.7 - 2.0 % ). These results suggest that when compared to the SRM, the Wattbike has acceptable accuracy. Reliability data suggest coaches and cyclists may need to use some cau- tion when using the Wattbike at low power out- puts in a test-retest setting.

/pdf/validity-and-reliability-of-the-wattbike-cycle-ergometer-qa0f9nss3g.pdf

Validity and Reliability of the Wattbike Cycle Ergometer

PURPOSE: Blackcurrant intake increases peripheral blood flow in humans, potentially by anthocyanin-induced vasodilation which may affect substrate delivery and exercise performance. We examined the effects of New Zealand blackcurrant (NZBC) extract on substrate oxidation, cycling time-trial performance and plasma lactate responses following the time-trial in trained cyclists. 
METHODS: Using a randomized, double-blind, crossover design, fourteen healthy men (age: 38 ± 13 years, height: 178 ± 4 cm, body mass: 77 ± 9 kg, VO2max: 53 ± 6 ml·kg-1·min-1, mean ± SD) ingested NZBC extract (300 mg∙day-1 CurraNZ™ containing 105 mg anthocyanin) or placebo (PL, 300 mg microcrystalline cellulose M102) for 7-days (washout 14-days). On day 7, participants performed 30 min of cycling (3x10 min at 45, 55 and 65% VO2max), followed by a 16.1 km time-trial with lactate sampling during a 20-minute passive recovery. 
RESULTS: NZBC extract increased fat oxidation at 65% VO2max by 27% (P < 0.05) and improved 16.1 km time-trial performance by 2.4% (NZBC: 1678 ± 108 s, PL: 1722 ± 131 s, P < 0.05). Plasma lactate was higher with NZBC extract immediately following the time-trial (NZBC: 7.06 ± 1.73 mmol∙L-1, PL: 5.92 ± 1.58 mmol∙L-1 P < 0.01). 
CONCLUSIONS: Seven days intake of New Zealand blackcurrant extract improves 16.1 km cycling time-trial performance and increases fat oxidation during moderate intensity cycling.

/pdf/new-zealand-blackcurrant-extract-improves-cycling-oj9rqd81j2.pdf

New Zealand blackcurrant extract improves cycling performance and fat oxidation in cyclists.

Carrying loads close to the trunk with a backpack causes a restrictive type of change in lung function in which Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 s (FEV1) are reduced without a corresponding decrement in the FEV1FVC( - 1) % It is not known whether this is due to the weight of the load acting on the chest or to the tightness of fit of the shoulder and chest straps and waist belt of the pack harness This study examined FVC, FEV1, FEV1FVC( - 1) %, peak expiratory flow (PEF), forced expiratory flow between 02 and 12 s (FEF02 - 12) after the start of expiration and between 25 and 75% of each FVC (FEF25 - 75%) in 12 healthy males wearing a 15 kg backpack in which the shoulder and chest straps and hip belt were loosened by 3 cm from a 'comfort fit' to achieve a 'loose pack' fit (LPF) and tightened by 3 cm from CF to achieve a 'tight pack' fit (TPF) In comparison with the control condition of no pack, a loose pack fit significantly reduced FVC (by 36%, p < 001), FEV1 (by 43%, p < 001) and FEF25 - 75% (by 84%, p < 001) A tight pack fit significantly reduced FVC (by 81%, p < 001) and FEV1 (by 91%, p < 0001) It also significantly reduced FEF02 - 12 (by 73%, p < 005) and FEF25 - 75% (by 21%, p < 001) In comparison with a loose pack fit, the tight pack fit was associated with a significantly lower FVC (by 46%, p < 001), FEV1 (by 50%, p < 001), FEF25 - 75% (by 138%, p < 001) and a fall in FEF02 - 12 (by 55%) The latter was approaching significance (p = 0077) There were no significant changes in FEV1FVC( - 1)% and PEF It is concluded that tightening the fit of a backpack significantly affects lung function in a manner that is typical of a restrictive change in lung function and is very similar in pattern to that of wearing a loosely fitted loaded backpack The effect of tightness of fit is additional to that due to the weight of the load alone and may also reduce expiratory flow at low lung volumes

Stephen D. Myers

Papers

Effect of exercise on cerebral perfusion in humans at high altitude

Exercise, plasma catecholamine concentrations and decision-making performance of soccer players on a soccer-specific test.

Validity and Reliability of the Wattbike Cycle Ergometer

New Zealand blackcurrant extract improves cycling performance and fat oxidation in cyclists.

Effect of backpack fit on lung function.