scholarly journals A Combination of Amino Acids and Caffeine Enhances Sprint Running Capacity in a Hot, Hypoxic Environment

Author(s):  
Tom R. Eaton ◽  
Aaron Potter ◽  
François Billaut ◽  
Derek Panchuk ◽  
David B. Pyne ◽  
...  

Heat and hypoxia exacerbate central nervous system (CNS) fatigue. We therefore investigated whether essential amino acid (EAA) and caffeine ingestion attenuates CNS fatigue in a simulated team sport–specific running protocol in a hot, hypoxic environment. Subelite male team sport athletes (n = 8) performed a repeat sprint running protocol on a nonmotorized treadmill in an extreme environment on 4 separate occasions. Participants ingested one of four supplements: a double placebo, 3 mg.kg-1 body mass of caffeine + placebo, 2 × 7 g EAA (Musashi Create)+placebo, or caffeine + EAA before each exercise session using a randomized, double-blind crossover design. Electromyography (EMG) activity and quadriceps evoked responses to magnetic stimulation were assessed from the dominant leg at preexercise, halftime, and postexercise. Central activation ratio (CAR) was used to quantify completeness of quadriceps activation. Oxygenation of the prefrontal cortex was measured via near-infrared spectroscopy. Mean sprint work was higher (M = 174 J, 95% CI [23, 324], p < .05, d = 0.30; effect size, likely beneficial) in the caffeine + EAA condition versus EAAs alone. The decline in EMG activity was less (M = 13%, 95% CI [0, 26]; p < .01, d = 0.58, likely beneficial) in caffeine + EAA versus EAA alone. Similarly, the pre- to postexercise decrement in CAR was significantly less (M = −2.7%, 95% CI [0.4, 5.4]; p < .05, d = 0.50, likely beneficial) when caffeine + EAA were ingested compared with placebo. Cerebral oxygenation was lower (M = −5.6%, 95% CI [1.0, 10.1]; p < .01, d = 0.60, very likely beneficial) in the caffeine + EAA condition compared with LNAA alone. Coingestion of caffeine and EAA appears to maintain muscle activation and central drive, with a small improvement in running performance.

2016 ◽  
Vol 41 (12) ◽  
pp. 1225-1232 ◽  
Author(s):  
Lieselot Decroix ◽  
Cajsa Tonoli ◽  
Danusa D. Soares ◽  
Semah Tagougui ◽  
Elsa Heyman ◽  
...  

Acute exercise-induced improvements in cognitive function are accompanied by increased (cerebral) blood flow and increased brain-derived neurotrophic factor (BDNF) levels. Acute cocoa flavanol (CF) intake may improve cognitive function, cerebral blood flow (in humans), and BNDF levels (in animals). This study investigated (i) the effect of CF intake in combination with exercise on cognitive function and (ii) cerebral hemodynamics and BDNF in response to CF intake and exercise. Twelve healthy men participated in this randomized, double-blind, crossover study. Participants performed a cognitive task (CT) at 100 min after acute 903-mg CF or placebo (PL) intake, followed by a 30-min time-trial. Immediately after this exercise, the same CT was performed. Prefrontal near-infrared spectroscopy was applied during CT and exercise to measure changes in oxygenated (ΔHbO2), deoxygenated (ΔHHb), and total haemoglobin (ΔHbtot) and blood samples were drawn and analyzed for BDNF. Reaction time was faster postexercise, but was not influenced by CF. ΔHbO2 during the resting CT was increased by CF, compared with PL. ΔHbO2, ΔHHb, and ΔHbtot increased in response to exercise without any effect of CF. During the postexercise cognitive task, there were no hemodynamic differences between CF or PL. Serum BDNF was increased by exercise, but was not influenced by CF. In conclusion, at rest, CF intake increased cerebral oxygenation, but not BDNF concentrations, and no impact on executive function was detected. This beneficial effect of CF on cerebral oxygenation at rest was overruled by the strong exercise-induced increases in cerebral perfusion and oxygenation.


2008 ◽  
Vol 18 (6) ◽  
pp. 639-652 ◽  
Author(s):  
Nicole D. Park ◽  
Robert D. Maresca ◽  
Kimberly I. McKibans ◽  
D. Reid Morgan ◽  
Timothy S. Allen ◽  
...  

The study’s objective was to determine whether orally ingested caffeine could help overcome excitation-contraction-coupling failure, which has been suggested to explain part of the strength loss associated with eccentric-contraction-induced muscle injury. A sample of 13 college students (4 men and 9 women) was used in a double-blind, repeated-measures experimental design. Each participant performed 2 experimental trials, 1 with each leg, with each trial lasting 4 consecutive days. On a given day, each participant was randomly assigned to ingest a capsule containing 6 mg/kg of either caffeine or flour (placebo). On the day of and the first 2 days after a bout of 50 injurious eccentric contractions done by the knee extensors, the interpolated-twitch technique was used to assess electrically evoked strength, maximal voluntary isometric contraction (MVIC) strength, and percent muscle activation during MVIC both before and after capsule ingestion. These variables were also measured before and after capsule ingestion the day before the eccentric-contraction bout—when the muscle was uninjured. In injured muscle, caffeine had no effect on any variable. In uninjured muscle, caffeine also had no effect on electrically evoked strength but increased MVIC strength by 10.4% compared with placebo (p = .00002), and this was attributed to an increase in muscle activation (6.2%; p = .01). In conclusion, the data provide no evidence that caffeine ingestion can help overcome excitation-contraction-coupling failure, if it exists, in injured human muscle. The data do indicate that caffeine ingestion can increase MVIC strength and activation in uninjured muscle but not in injured muscle.


1999 ◽  
Vol 277 (3) ◽  
pp. H1045-H1052 ◽  
Author(s):  
H. B. Nielsen ◽  
R. Boushel ◽  
P. Madsen ◽  
N. H. Secher

The combined effects of hyperventilation and arterial desaturation on cerebral oxygenation ([Formula: see text]) were determined using near-infrared spectroscopy. Eleven competitive oarsmen were evaluated during a 6-min maximal ergometer row. The study was randomized in a double-blind fashion with an inspired O2 fraction of 0.21 or 0.30 in a crossover design. During exercise with an inspired O2 fraction of 0.21, the arterial CO2 pressure (35 ± 1 mmHg; mean ± SE) and O2 pressure (77 ± 2 mmHg) as well as the hemoglobin saturation (91.9 ± 0.7%) were reduced ( P < 0.05).[Formula: see text] was reduced from 80 ± 2 to 63 ± 2% ( P < 0.05), and the near-infrared spectroscopy-determined concentration changes in deoxy- (ΔHb) and oxyhemoglobin (ΔHbO2) of the vastus lateralis muscle increased 22 ± 3 μM and decreased 14 ± 3 μM, respectively ( P < 0.05). Increasing the inspired O2fraction to 0.30 did not affect ventilation (174 ± 4 l/min), but arterial CO2 pressure (37 ± 2 mmHg), O2 pressure (165 ± 5 mmHg), and hemoglobin O2saturation (99 ± 0.1%) increased ( P < 0.05).[Formula: see text] remained close to the resting level during exercise (79 ± 2 vs. 81 ± 2%), and although the muscle ΔHb (18 ± 2 μM) and ΔHbO2 (−12 ± 3 μM) were similar to those established without O2 supplementation, work capacity increased from 389 ± 11 to 413 ± 10 W ( P < 0.05). These results indicate that an elevated inspiratory O2fraction increases exercise performance related to maintained cerebral oxygenation rather than to an effect on the working muscles.


2008 ◽  
Vol 18 (2) ◽  
pp. 131-141 ◽  
Author(s):  
C. Martyn Beaven ◽  
Will G. Hopkins ◽  
Kier T. Hansen ◽  
Matthew R. Wood ◽  
John B. Cronin ◽  
...  

Introduction:Interest in the use of caffeine as an ergogenic aid has increased since the International Olympic Committee lifted the partial ban on its use. Caffeine has beneficial effects on various aspects of athletic performance, but its effects on training have been neglected.Purpose:To investigate the acute effect of caffeine on the exercise-associated increases in testosterone and cortisol in a double-blind crossover study.Methods:Twenty-four professional rugby-league players ingested caffeine doses of 0, 200, 400, and 800 mg in random order 1 hr before a resistance-exercise session. Saliva was sampled at the time of caffeine ingestion, at 15-min intervals throughout each session, and 15 and 30 min after the session. Data were log-transformed to estimate percent effects with mixed modeling, and effects were standardized to assess magnitudes.Results:Testosterone concentration showed a small increase of 15% (90% confidence limits, ± 19%) during exercise. Caffeine raised this concentration in a dose-dependent manner by a further small 21% (± 24%) at the highest dose. The 800-mg dose also produced a moderate 52% (± 44%) increase in cortisol. The effect of caffeine on the testosterone:cortisol ratio was a small decline (14%; ± 21%).Conclusion:Caffeine has some potential to benefit training outcomes via the anabolic effects of the increase in testosterone concentration, but this benefit might be counteracted by the opposing catabolic effects of the increase in cortisol and resultant decline in the testosterone:cortisol ratio.


1999 ◽  
Vol 88 (3) ◽  
pp. 554-558 ◽  
Author(s):  
A. Timothy Lovell ◽  
Huw Owen-Reece ◽  
Clare E. Elwell ◽  
Martin Smith ◽  
John C. Goldstone

2006 ◽  
Vol 59 (3) ◽  
pp. 462-465 ◽  
Author(s):  
Nicole Nagdyman ◽  
Thilo Fleck ◽  
Birgit Bitterling ◽  
Peter Ewert ◽  
Hashim Abdul-Khaliq ◽  
...  

Neonatology ◽  
2021 ◽  
pp. 1-6
Author(s):  
Bi Ze ◽  
Lili Liu ◽  
Ge Sang Yang Jin ◽  
Minna Shan ◽  
Yuehang Geng ◽  
...  

<b><i>Background:</i></b> Accurate detection of cerebral oxygen saturation (rSO<sub>2</sub>) may be useful for neonatal brain injury prevention, and the normal range of rSO<sub>2</sub> of neonates at high altitude remained unclear. <b><i>Objective:</i></b> To compare cerebral rSO<sub>2</sub> and cerebral fractional tissue oxygen extraction (cFTOE) at high-altitude and low-altitude areas in healthy neonates and neonates with underlying diseases. <b><i>Methods:</i></b> 515 neonates from low-altitude areas and 151 from Tibet were enrolled. These neonates were assigned into the normal group, hypoxic-ischemic encephalopathy (HIE) group, and other diseases group. Near-infrared spectroscopy was used to measure rSO<sub>2</sub> in neonates within 24 h after admission. The differences of rSO<sub>2</sub>, pulse oxygen saturation (SpO<sub>2</sub>), and cFTOE levels were compared between neonates from low- and high-altitude areas. <b><i>Results:</i></b> (1) The mean rSO<sub>2</sub> and cFTOE levels in normal neonates from Tibet were 55.0 ± 6.4% and 32.6 ± 8.5%, significantly lower than those from low-altitude areas (<i>p</i> &#x3c; 0.05). (2) At high altitude, neonates with HIE, pneumonia (<i>p</i> &#x3c; 0.05), anemia, and congenital heart disease (<i>p</i> &#x3c; 0.05) have higher cFTOE than healthy neonates. (3) Compared with HIE neonates from plain areas, neonates with HIE at higher altitude had lower cFTOE (<i>p</i> &#x3c; 0.05), while neonates with heart disease in plateau areas had higher cFTOE than those in plain areas (<i>p</i> &#x3c; 0.05). <b><i>Conclusions:</i></b> The rSO<sub>2</sub> and cFTOE levels in normal neonates from high-altitude areas are lower than neonates from the low-altitude areas. Lower cFTOE is possibly because of an increase in blood flow to the brain, and this may be adversely affected by disease states which may increase the risk of brain injury.


1996 ◽  
Vol 81 (3) ◽  
pp. 1174-1183 ◽  
Author(s):  
H. Obrig ◽  
C. Hirth ◽  
J. G. Junge-Hulsing ◽  
C. Doge ◽  
T. Wolf ◽  
...  

We studied cerebral hemodynamic response to a sequential motor task in 56 subjects to investigate the time course and distribution of blood oxygenation changes as monitored by near-infrared spectroscopy (NIRS). To address whether response is modulated by different performance velocities, a group of subjects (n = 12) was examined while performing the motor task at 1, 2, and 3 Hz. The results demonstrate that 1) the NIRS response reflects localized changes in cerebral hemodynamics, 2) the response, consisting of an increase in oxygenated hemoglobin concentration [oxy-Hb] and a decrease in deoxygenated hemoglobin concentration ([deoxy-Hb]), is lateralized and increases in amplitude with higher performance rates, and 3) changes in [oxy-Hb] and [deoxy-Hb] differ in time course. Changes in [oxy-Hb] are biphasic, with a fast initial increase and a pronounced poststimulus undershoot. The stimulus-associated decrease in [deoxy-Hb] is monophasic, and response latency is greater. We conclude that NIRS is able to detect even small changes in cerebral hemodynamic response to functional stimulation.


2021 ◽  

Hypoxic-ischemic brain injury (HIBI) is a leading cause of mortality in post-cardiac arrest (post-CA) patients who successfully survive the initial cardiopulmonary resuscitation (CPR) but later die in the Intensive Care Unit (ICU). Therefore, a key priority of post-resuscitation ICU care is to prevent and limit the impact of HIBI by optimizing the balance between cerebral oxygen delivery and demand. Traditionally, an optimal systemic oxygen balance is considered to ensure the brain’s oxygen balance. However, the validity of this assumption is uncertain, as the brain constitutes only 2%of the body mass while accounting for approximately 20% of basal oxygen consumption at rest. Hence, there is a real need to monitor cerebral oxygenation realistically. Several imaging and bedside monitoring methods are available for cerebral oxygenation monitoring in post-CA patients. Unfortunately, each of them has its limitations. Imaging methods require transporting a critically ill unstable patient to the scanner. Moreover, they provide an assessment of the oxygenation state only at a particular moment, while brain oxygenation is dynamic. Bedside methods, specifically near-infrared spectroscopy (NIRS), brain tissue oxygen tension (PbtO2), and jugular venous oxygen saturation monitoring (SjvO2), have not often been used in studies involving post-CA patients. Hence there is ambiguity regarding clear recommendations for using these bedside monitors. Presently, the most promising option seems to be using the NIRS as an indicator of effective CPR. We present a narrative review focusing on bedside methods and discuss the evidence for their use in adult patients after cardiac arrest.


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