Caffeine is probably the most used supplement alongside protein for gym sessions.
How often have you heard someone talking about a new pre-workout shake they’ve bought or noticed gym selling the new more easily consumable shots. What’s in these pricey shots? Caffeine and beta alanine. Pre-workouts don’t vary much in terms of content, more caffeine content and flavour. Question is, being so consumable how exactly do they work….
When caffeine is consumed orally, be it via beverage, shake or shot it’s absorbed in the GI tract within approximately 45 minutes. Although caffeine absorption begins in the stomach, this process takes place mainly within the small intestine. Caffeine values peak in the blood approximately 1 hour after ingestion.
Caffeine is converted to a variety of metabolites by the liver microsomal enzyme system. These metabolites account for almost all caffeine excretion, as only 1% to 2% of an administered dose is excreted unchanged. In humans, approximately 95% of caffeine metabolites are eliminated through the urine, 2% to 5% through the faeces, and the remainder through other bodily fluids such as saliva.
Caffeine has been shown to produce effects such as a stimulant (however this also includes tachycardia, hypertension, and hypothermia, stimulation of the responses of the heart, vasculature and adipose tissue).
Tachycardia – increased heart rate Hypertension – Increased blood pressure Hypothermia – artificial reduction of body temperature.
All of this is in addition to the stress of a workout (yes, all workouts are a from of stress). So what's the draw backs to all these pre-workouts?
The Health Risks
The following health related topics have all been linked to caffeine intake:
• sleep deprivation – due to stimulant effects
• caffeine and its demethylated metabolites in lactation – it has been found that the metabolites of caffeine can be passed to the feeding infant in the breast milk. Which is why pregnant woman can’t or shouldn’t drink coffee.
• caffeine and chronic back pain – this is most probably due to the diuretic effect of the caffeine on the kidneys, which could then produce referred back pain.
• caffeine and enhanced drug metabolism in children with cystic fibrosis – as caffeine is a stimulant it can, in some cases speed up the bodies metabolism of a drug.
• caffeinated beverages, decaffeinated coffee and spontaneous abortion
• Caffeine has been found to heighten stress levels in any work situation. Caffeine can increase excretion of the stress hormone epinephrine by as much as 32%.
But it’s not without its benefits…..Many new studies have found beneficial antioxidant flavenoids in tea and cocoa and these are beneficial to cardiovascular health. You require about 150mg of flavenoids to produce an antioxidant response. Tea contains approximately 172mg per 235ml (brewed for 2 minutes).
The Food Standards Agency has advised on the following levels of caffeine in hot
Caffeine and water loss
The following figures will enable you to calculate water losses due the diuretic effects of caffeine; a diuretic is a drug that increases the volume of urine produced by promoting the excretion of salts and water from the kidney. In medicine a diuretic is used to counteract oedema, and high blood pressure.
50mg Caffeine = 60ml fluid lost
Therefore, 1 Cup of coffee = 125mg Caffeine = loss of 146ml of fluid An average cup contains 200ml fluid
Therefore, from a cup of coffee you get a net gain of 54ml of fluid.
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