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1.
New Zealand blackcurrant extract enhances muscle oxygenation during repeated intermittent forearm muscle contractions in advanced and elite rock climbers.
Fryer, S, Giles, D, Bird, E, Stone, K, Paterson, C, Baláš, J, Willems, MET, Potter, JA, Perkins, IC
European journal of sport science. 2021;(9):1290-1298
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Abstract
Anthocyanin-rich New Zealand blackcurrant (NZBC) may improve forearm muscle oxygenation and enhance performance in high-level rock climbers. As such, using a double-blind, randomised, cross-over design study, twelve participants performed an oxidative capacity assessment, and two successive exhaustive exercise trials (submaximal forearm muscle contractions at 60% of their maximal volitional contraction). Each visit was conducted following 7-days intake of 600 mg·day-1 NZBC extract or placebo. Oxidative capacity was estimated by calculating the oxygen half time recovery using near infrared spectroscopy. Time to exhaustion (s), impulse (kg·s), and minimum tissue saturation index (min-TSI %) were assessed during both the exercise trials. Muscle oxidative capacity was greater with NZBC (mean difference [MD] = 5.3 s, 95% confidence intervals [95% CI] = 0.4-10.2 s; p = 0.036; Cohen's d = 0.94). During the exercise trials, there was an interaction for min-TSI % (time x condition, p = 0.046; ηp2 = 0.372), which indicated a greater level of oxygen extraction during trial two with NZBC extract (MD = 9%, 95% CI = 2-15%) compared to the placebo (MD = 2%, 95% CI = 1-7%). There was a decrease in time to exhaustion (p <0.001, ηp2 = 0.693) and impulse (p = 0.001, ηp2 = 0.672) in exercise trial two, with no effect of NZBC extract. In high-level rock climbers 7-days NZBC extract improves forearm muscle oxygenation with no effect on isolated forearm muscle performance.
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Are Pre-Ascent Low-Altitude Saliva Cortisol Levels Related to the Subsequent Acute Mountain Sickness Score? Observations from a Field Study.
Gatterer, H, Bernatzky, G, Burtscher, J, Rainer, M, Kayser, B, Burtscher, M
High altitude medicine & biology. 2019;(4):337-343
Abstract
Background: The associations among cortisol levels, body water status, and acute mountain sickness (AMS) remain unclear. We investigated associations between AMS prevalence and severity with resting saliva cortisol levels at low altitude (LA) and high altitude (HA) and with fluid balance during a HA stay. Methods: Twenty-two physically fit and healthy participants (12 women, 10 men) were transported to HA (Testa Grigia, 3480 m). In the late afternoon at LA, on the next day 3-4 hours after arrival at HA and in the morning after an overnight stay, heart rate, oxygen saturation, and systolic and diastolic blood pressures were measured in a sitting position after 10 minutes of rest; cortisol levels were quantified in saliva samples taken pre-ascent and 3-4 hours after arrival at HA. AMS was scored with the 1993 Lake Louise Score (LLS, cut-off ≥3). Urine volume and fluid and food intake were recorded during the altitude stay. Results: Pre-ascent cortisol levels were associated with fluid retention during the altitude stay (r2 = 0.33, p < 0.05) and both were positively related to the LLS (r2 = 0.49 and r2 = 0.26, p < 0.05, respectively). Conclusions: In conclusion, resting LA cortisol levels and fluid retention upon rapid exposure to altitude seem to be associated with AMS. This suggests a potential link among cortisol homeostasis, fluid balance, and AMS risk.
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NSE & S100B protein blood level assessment during a long-distance trail race.
Jouffroy, R, Alves, B, Mauvieux, B, Mallet, L, Beaudeux, JL, Cottart, CH
Annales de biologie clinique. 2019;(5):532-536
Abstract
UNLABELLED The acute and chronic consequences of long-distance running on brain function have received little attention. The impact of such a hard-physical burden associated with sleep privation during such events such has never been explored in terms of neuropsychological function and brain damage. METHODS Blood samples were collected from 4 athletes before, during and at the end of one of two races: Grand Raid de la Réunion 2017 (GRR: 165 km, elevation gain: 9529 m, 2 runners) and Trail de la Bourbon 2017 (TB: 111 km, elevation gain: 6433 m, 2 runners). Serum S100B and NSE levels were measured for each runner before, during and after the race. RESULTS Serum S100B levels (normal range: < 0.15 μg/L) increased early during the race and remained high up to the end of the race in all 4 runners (range: 0.17-0.59 μg/L). NSE level (normal range: < 15 μg/L) increased in 3 of the 4 runners (range: 16.8-39.2 μg/L). CONCLUSIONS This preliminary study shows the potential interest of S100B and NSE serum assessment during long-distance races. Further studies are needed to confirm these results and to investigate the origins and significance of this increase in brain injury markers.
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Responses of peripheral blood mononuclear cells to moderate exercise and hypoxia.
Morabito, C, Lanuti, P, Caprara, GA, Guarnieri, S, Verratti, V, Ricci, G, Catizone, A, Marchisio, M, Fanò-Illic, G, Mariggiò, MA
Scandinavian journal of medicine & science in sports. 2016;(10):1188-99
Abstract
The purpose of this study was to analyze the physiological features of peripheral blood mononuclear cells (PBMCs) isolated from healthy female trekkers before and after physical activity carried out under both normoxia (low altitude, < 2000 m a.s.l.) and hypobaric hypoxia (high altitude, > 3700 m a.s.l.). The experimental design was to differentiate effects induced by exercise and those related to external environmental conditions. PBMCs were isolated from seven female subjects before and after each training period. The PBMCs were phenotypically and functionally characterized using fluorimetric and densitometric analyses, to determine cellular activation, and their intracellular Ca(2+) levels and oxidative status. After a period of normoxic physical exercise, the PBMCs showed an increase in fully activated T lymphocytes (CD3(+) CD69(+) ) and a reduction in intracellular Ca(2+) levels. On the other hand, with physical exercise performed under hypobaric hypoxia, there was a reduction in T lymphocytes and an increase in nonactivated B lymphocytes, accompanied by a reduction in O2 (-) levels in the mitochondria. These outcomes reveal that in women, low- to moderate-intensity aerobic trekking induces CD69 T cell activation and promotes anti-stress effects on the high-altitude-induced impairment of the immune responses and the oxidative balance.
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Oral Coenzyme Q10 supplementation does not prevent cardiac alterations during a high altitude trek to everest base cAMP.
Holloway, CJ, Murray, AJ, Mitchell, K, Martin, DS, Johnson, AW, Cochlin, LE, Codreanu, I, Dhillon, S, Rodway, GW, Ashmore, T, et al
High altitude medicine & biology. 2014;(4):459-67
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Abstract
Exposure to high altitude is associated with sustained, but reversible, changes in cardiac mass, diastolic function, and high-energy phosphate metabolism. Whilst the underlying mechanisms remain elusive, tissue hypoxia increases generation of reactive oxygen species (ROS), which can stabilize hypoxia-inducible factor (HIF) transcription factors, bringing about transcriptional changes that suppress oxidative phosphorylation and activate autophagy. We therefore investigated whether oral supplementation with an antioxidant, Coenzyme Q10, prevented the cardiac perturbations associated with altitude exposure. Twenty-three volunteers (10 male, 13 female, 46±3 years) were recruited from the 2009 Caudwell Xtreme Everest Research Treks and studied before, and within 48 h of return from, a 17-day trek to Everest Base Camp, with subjects receiving either no intervention (controls) or 300 mg Coenzyme Q10 per day throughout altitude exposure. Cardiac magnetic resonance imaging and echocardiography were used to assess cardiac morphology and function. Following altitude exposure, body mass fell by 3 kg in all subjects (p<0.001), associated with a loss of body fat and a fall in BMI. Post-trek, left ventricular mass had decreased by 11% in controls (p<0.05) and by 16% in Coenzyme Q10-treated subjects (p<0.001), whereas mitral inflow E/A had decreased by 18% in controls (p<0.05) and by 21% in Coenzyme Q10-treated subjects (p<0.05). Coenzyme Q10 supplementation did not, therefore, prevent the loss of left ventricular mass or change in diastolic function that occurred following a trek to Everest Base Camp.
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The practical aspects of insulin at high altitude.
Richards, P, Hillebrandt, D
High altitude medicine & biology. 2013;(3):197-204
Abstract
With the increasing prevalence of diabetes and current social philosophy of enablement, many more diabetics are travelling to high altitude where the rate of AMS in Type 1 diabetic mountaineers is no different than nondiabetics. Numerous effects of exercise, both degree and duration, dietary change, illness, stress, mountain sickness, counter-regulatory hormones, and altitude increased sympathetic output, and catecholamines have led to conflicting accounts of insulin requirement increasing or decreasing at altitude. Overall, it would appear that the effects of diet and exercise outweigh those of altitude. Good control requires continual insulin dose adjustment with frequent feedback from blood sugar testing, but glucometers can over- or under-read at altitude. Additionally, heat or cold exposure can degrade insulin efficacy; strategies for storing insulin are described.
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Acute mountain sickness prophylaxis: a high-altitude perspective.
DeLellis, SM, Anderson, SE, Lynch, JH, Kratz, K
Current sports medicine reports. 2013;(2):110-4
Abstract
Acute mountain sickness (AMS) is the most common form of altitude illness affecting athletes and adventurists who work or play at elevations greater than 10,000 ft above mean sea level. Considerable research has been conducted to mitigate risk for those who work or play in environmental extremes. This article describes the experiences of a group of U.S. Army Special Operations soldiers who tested recommended doses of acetazolamide prophylaxis for AMS during six expeditions to elevations between 19,000 and 23,000 ft. In addition, we briefly review the literature as it pertains to prophylaxis of AMS. In our experience, prophylaxis with the recommended doses of acetazolamide resulted in fewer AMS symptoms and seemed to confer a higher likelihood of successfully summiting each peak. We conclude that acetazolamide is an acceptable choice for AMS prevention along with a slow, controlled ascent and proper fitness, nutrition, clothing, and gear.
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A comparison of the effects of a high carbohydrate vs. a higher protein milk supplement following simulated mountain skirmishes.
Jimenez-Flores, R, Heick, J, Davis, SC, Hall, KG, Schaffner, A
Military medicine. 2012;(6):723-31
Abstract
This study compared the effects of a higher protein supplement manufactured from milk vs. a commercially available higher carbohydrate supplement on serum markers of muscle damage, anaerobic exercise, choice reaction time, and body composition during 2 weekends of vigorous hikes with simulated mountain skirmishes. Thirty-five university students, including Reserve Officers Training Corps cadets and athletes, carried 25% of their body weight (up to 26.4 kg) on Friday, Saturday, and Sunday hikes. Supplementation and Wingate tests followed each hike, and choice reaction testing preceded and followed each hike. Blood samples were obtained and body compositions were measured pre- and postweekend. Increased cortisol, highly sensitive C-reactive protein, creatine phosphokinase, and aldolase suggested the exercise regimen induced muscle damage and inflammation, which was attenuated during the second weekend of hikes. Absolute anaerobic capacity was somewhat greater following consumption of the milk supplement (p = 0.082). Body compositions did not change significantly during this study. Choice reaction times decreased following hikes and were significantly faster following consumption of the carbohydrate supplement (p < 0.04). Supplements including milk proteins and carbohydrates may improve endurance exercise and decision-making abilities of military personnel and endurance athletes.
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Energy expenditure during 2-day trail walking in the mountains (2,857 m) and the effects of amino acid supplementation in older men and women.
Shimizu, M, Miyagawa, K, Iwashita, S, Noda, T, Hamada, K, Genno, H, Nose, H
European journal of applied physiology. 2012;(3):1077-86
Abstract
We compared relative exercise intensity and active energy expenditure (AEE) on trail walking in the mountains, with those of daily exercise training, and whether branched-chain amino acid (BCAA) and arginine supplementation attenuated the release of markers indicating muscle damage and declines in physical performance. Twenty-one subjects (~63 years) were divided into two groups: amino acid (AA, 51 g of amino acids and 40 g of carbohydrate, male/female = 6/4) or placebo (PL, 91 g of carbohydrate, male/female = 6/5) supplementation during 2 days of trail walking in the mountains. We measured heart rate (HR), AEE, fatigue sensation, water and food intake, and sweat loss during walking. In addition, we measured peak aerobic capacity [Formula: see text] and heart rate (HR(peak)) with graded-intensity walking, vertical jumping height (VJ) before and after walking. We found that average HR and AEE during uphill walking were ~100% HR(peak) and ~60% [Formula: see text], while they were ~80 and ~20% during downhill walking, respectively. Moreover, average total AEE per day was sevenfold that of their daily walking training. VJ after walking remained unchanged compared with the baseline in AA (P > 0.2), while it was reduced by ~10% in PL (P < 0.01), although with no significant difference in the reduction between the groups (P > 0.4). The responses of other variables were not significantly different between groups (all, P > 0.2). Thus, trail walking in the mountains required a high-intensity effort for older people, while the effects of BCAA and arginine supplementation were modest in this condition.
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10.
Neuromuscular consequences of an extreme mountain ultra-marathon.
Millet, GY, Tomazin, K, Verges, S, Vincent, C, Bonnefoy, R, Boisson, RC, Gergelé, L, Féasson, L, Martin, V
PloS one. 2011;(2):e17059
Abstract
We investigated the physiological consequences of one of the most extreme exercises realized by humans in race conditions: a 166-km mountain ultra-marathon (MUM) with 9500 m of positive and negative elevation change. For this purpose, (i) the fatigue induced by the MUM and (ii) the recovery processes over two weeks were assessed. Evaluation of neuromuscular function (NMF) and blood markers of muscle damage and inflammation were performed before and immediately following (n = 22), and 2, 5, 9 and 16 days after the MUM (n = 11) in experienced ultra-marathon runners. Large maximal voluntary contraction decreases occurred after MUM (-35% [95% CI: -28 to -42%] and -39% [95% CI: -32 to -46%] for KE and PF, respectively), with alteration of maximal voluntary activation, mainly for KE (-19% [95% CI: -7 to -32%]). Significant modifications in markers of muscle damage and inflammation were observed after the MUM as suggested by the large changes in creatine kinase (from 144 ± 94 to 13,633 ± 12,626 UI L(-1)), myoglobin (from 32 ± 22 to 1,432 ± 1,209 µg L(-1)), and C-Reactive Protein (from <2.0 to 37.7 ± 26.5 mg L(-1)). Moderate to large reductions in maximal compound muscle action potential amplitude, high-frequency doublet force, and low frequency fatigue (index of excitation-contraction coupling alteration) were also observed for both muscle groups. Sixteen days after MUM, NMF had returned to initial values, with most of the recovery process occurring within 9 days of the race. These findings suggest that the large alterations in NMF after an ultra-marathon race are multi-factorial, including failure of excitation-contraction coupling, which has never been described after prolonged running. It is also concluded that as early as two weeks after such an extreme running exercise, maximal force capacities have returned to baseline.