Author Topic: sodium and endurance  (Read 1965 times)

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adarqui

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sodium and endurance
« on: December 22, 2015, 04:21:21 pm »
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adarqui

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Re: sodium and endurance
« Reply #1 on: December 22, 2015, 04:21:51 pm »
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http://download.springer.com/static/pdf/802/art%253A10.1186%252F1550-2783-10-16.pdf?originUrl=http%3A%2F%2Fjissn.biomedcentral.com%2Farticle%2F10.1186%2F1550-2783-10-16&token2=exp=1450819403~acl=%2Fstatic%2Fpdf%2F802%2Fart%25253A10.1186%25252F1550-2783-10-16.pdf*~hmac=99cc7c4b97aea02fe10c4102be86f13ad101409a58e2257cb5fb6afe28a73bd3

Multiday acute sodium bicarbonate intake improves endurance capacity and reduces acidosis in men

Quote
Abstract
Background: The purpose was to investigate the effects of one dose of NaHCO3 per day for five consecutive days
on cycling time-to-exhaustion (Tlim) at ‘Critical Power’ (CP) and acid–base parameters in endurance athletes.
Methods: Eight trained male cyclists and triathletes completed two exercise periods in a randomized, placebo-controlled,
double-blind interventional crossover investigation. Before each period, CP was determined. Afterwards, participants
completed five constant-load cycling trials at CP until volitional exhaustion on five consecutive days, either after a dose
of NaHCO3 (0.3 g·kg−1 body mass) or placebo (0.045 g·kg−1 body mass NaCl).
Results: Average Tlim increased by 23.5% with NaHCO3 supplementation as compared to placebo (826.5 ± 180.1 vs.
669.0 ± 167.2 s; P = 0.001). However, there was no time effect for Tlim (P = 0.375). [HCO3

] showed a main effect for
condition (NaHCO3: 32.5 ± 2.2 mmol·l−1
; placebo: 26.2 ± 1.4 mmol·l−1
; P < 0.001) but not for time (P = 0.835). NaHCO3
supplementation resulted in an expansion of plasma volume relative to placebo (P = 0.003).
Conclusions: The increase in Tlim was accompanied by an increase in [HCO3

], suggesting that acidosis might be a
limiting factor for exercise at CP. Prolonged NaHCO3 supplementation did not lead to a further increase in [HCO3

] due
to the concurrent elevation in plasma volume. This may explain why Tlim remained unaltered despite the prolonged
NaHCO3 supplementation period. Ingestion of one single NaHCO3 dose per day before the competition during
multiday competitions or tournaments might be a valuable strategy for performance enhancement.

adarqui

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Re: sodium and endurance
« Reply #2 on: December 22, 2015, 04:22:59 pm »
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http://download.springer.com/static/pdf/746/art%253A10.1186%252F1550-2783-10-30.pdf?originUrl=http%3A%2F%2Fjissn.biomedcentral.com%2Farticle%2F10.1186%2F1550-2783-10-30&token2=exp=1450819623~acl=%2Fstatic%2Fpdf%2F746%2Fart%25253A10.1186%25252F1550-2783-10-30.pdf*~hmac=8293d01583054b099760ecbd617fd148cbd37bbc6c3f9f59766e535b0e87e567

Sodium supplementation has no effect on endurance performance during a cycling time-trial in cool conditions: a randomised cross-over trial

Quote
Abstract
Background: Sodium ingestion during exercise may exert beneficial effects on endurance performance by either its
ability to attenuate the decrease in plasma volume or reduce the risk of Exercise Associated Hyponatremia (EAH).
This study aimed to investigate the effect of sodium supplements on endurance performance during a 72 km road
cycling time-trial in cool conditions (13.8 ± 2.0°C).
Methods: Nine well-trained cyclists (5 male, 4 female) participated in this randomized, double-blinded cross-over
study, receiving either a 700 mg.
h-1 salt capsule, or a corn flour placebo during the time trial. Water was ingested
ad-libitum throughout the time trial. Measurements were taken pre, post, and 40 min following time-trials,
analysing blood, sweat, and urinary hydration and sodium concentration.
Results: Sodium supplements had no effect on time-trial performance (overall time = 171 min sodium vs. 172 min
placebo; p = 0.46). There was also no effect on the change in plasma sodium concentration from pre to post time
trial between trials (relative plasma [Na+
] change (pre-post): sodium = 0.56%, placebo = 0.47%; p = 0.60). The greatest
difference observed was a significantly change in plasma volume from pre to post exercise between the salt and
the placebo trial (p = 0.02), which corresponded with an increased thirst with sodium supplementation.
Conclusion: Sodium supplements therefore do not improving performance during exercise of approximately 3 h
duration in cool conditions.

adarqui

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Re: sodium and endurance
« Reply #3 on: December 22, 2015, 04:25:11 pm »
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http://link.springer.com/article/10.1007/s00421-014-3068-6

Impact of acute sodium citrate ingestion on endurance running performance in a warm environment

Quote
Abstract
Purpose
Dietary supplements inducing alkalosis have been shown to be ergogenic during intense endurance exercise in temperate environments, but there is lack of data regarding the efficacy of these substances in the heat. This study aimed to investigate the effect of sodium citrate (CIT) ingestion on 5,000-m running performance in a warm environment.
Methods
Sixteen non-heat-acclimated endurance-trained males (age 25.8 ± 4.4 years, VO2peak 56.9 ± 4.7 mL kg min) completed two 5,000-m self-paced treadmill runs with preceding CIT or placebo (wheat flour; PLC) ingestion in a double-blind, randomized, crossover manner in a climatic chamber (air temperature 32 °C, relative humidity 50 %).
Results
CIT ingestion (500 mg kg−1 body mass) compared to PLC induced increases in water retention, body mass and plasma volume (P < 0.05). Pre- and post-exercise blood HCO3 − concentration, base excess and pH were higher (P < 0.001) in CIT compared to PLC trial. Rectal temperature, body heat storage, heat storage rate, heart rate and 5,000-m running time (18.92 ± 2.05 min in CIT, 19.11 ± 2.38 min in PLC; 66 % likelihood of benefit, d = –0.09) were similar (P > 0.05) in the two trials. Post-exercise blood lactate concentration was higher (P < 0.001) in CIT (11.05 ± 3.22 mmol L−1) compared to PLC trial (8.22 ± 2.64 mmol L−1). Ratings of perceived exertion, fatigue and thermal sensation did not differ in the two trials (P > 0.05).
Conclusion
Acute CIT ingestion induces alkalosis, water retention, plasma volume expansion and an increase in post-exercise blood lactate concentration, but does not improve 5,000-m running performance in a warm environment in non-heat-acclimated endurance-trained males.

adarqui

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Re: sodium and endurance
« Reply #4 on: December 22, 2015, 04:28:36 pm »
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http://www.karger.com/Article/Abstract/341945


Salt and Fluid Loading: Effects on Blood Volume and Exercise Performance

Quote
Abstract
During prolonged exercise, fluid and salt losses through sweating reduce plasma volume which leads to heart rate drift in association with hyperthermia and reductions in performance. Oral rehydration with water reduces the loss of plasma volume and lessens heart rate drift and hyperthermia. Moreover, the inclusion of sodium in the rehydration solution to levels that double those in sweat (i.e., around 90 mmol/l Na+) restores plasma volume when ingested during exercise, and expands plasma volume if ingested pre-exercise. Pre-exercise salt and fluid ingestion with the intention of expanding plasma volume has received an increasing amount of attention in the literature in recent years. In four studies, pre-exercise salt and fluid ingestion improved performance, measured as time to exhaustion, either during exercise in a thermoneutral or in a hot environment. While in a hot environment, the performance improvements were linked to lowering of core temperatures and heart rate, the reasons for the improved performance in a thermoneutral environment remain unclear. However, when ingesting pre-exercise saline solutions above 0.9% (i.e., > 164 mmol/l Na+), osmolality and plasma sodium increase and core temperature remain at dehydration levels. Thus, too much salt counteracts the beneficial effects of plasma volume expansion on heat dissipation and hence in performance. In summary, the available literature suggests that pre-exercise saline ingestion with concentrations not over 164 mmol/l Na+ is an ergogenic aid for subsequent prolonged exercise in a warm or thermoneutral environment.