Soda and Caffeine (Page 2)

Sorry for reviving this but I don't believe that caffeine is completely innocent.  While something like coffee is mostly water, does your body absorb and retain that water the same way it absorbs water without caffeine?  Does the effects on the nervous system do anything to trigger getting rid of it any faster?

I can honestly say that despite my love of coffee, there is a huge difference in how I feel if I drink water all day versus drinking a pot of coffee. 

I know the article refers to "moderate" consumption so perhaps there is a curve here which factors in tolerance, effects on the nervous system, absorption and retention of water?

http://www.medicinenet.com/caffeine/page3.htm <http://www.medicinenet.com/caffeine/page3.htm> 

 Is caffeine a diuretic?

 Caffeine has been considered a diuretic by experts and consumers for years. Some people believe that drinking caffeinated beverages will cause them to lose fluids so they can't be counted as part of their daily intake. Others say that caffeinated beverages do not increase fluid losses. The best way to flush out the truth is to examine the research.

 Each day our body has a need for water. We lose water through respiration, skin, renal, and gastrointestinal tract losses. Our intake of water comes from liquids and foods. We need to maintain an adequate water balance for our bodies to function properly. Factors such as age, activity level, health, diet, and environment can affect our water balance.

 Some research has shown that caffeine intake can also affect our fluid balance. In one study, 12 caffeine consumers were told to abstain from caffeine for five days and were then given 642 mg of caffeine in the form of coffee. Their urine output increased when given the caffeine.

 Another study done on eight men tested the effect of 45, 90, 180, or 360 mg of caffeine on urine volume. An increase in urine volume was seen only at the 360-mg dose of caffeine. One limitation to these studies is that they did not evaluate the impact of caffeine when consumed on a regular basis. A onetime dose may affect the body differently than daily consumption.

 Back in 1928, caffeine was shown to have no significant impact on urinary output. Subsequent studies have shown that caffeine-containing beverages did not impact urinary output any differently than other beverages. Based on this, the Institute of Medicine recommends that "unless additional evidence becomes available indicating cumulative total water deficits in individuals with habitual intakes of significant amounts of caffeine, caffeinated beverages appear to contribute to the daily total water intake similar to that contributed by noncaffeinated beverages."

 This doesn't mean that caffeine does not increase your need to urinate. Your reaction can depend on the amount that you consume, the type of product, and your tolerance level. If you have urinary incontinence you may experience a greater "urgency" to urinate after consuming a caffeinated beverage. You will need to monitor your reaction and tolerance to caffeine to determine how you are affected. Water is still the recommended choice for optimal hydration, so be sure to include it as part of your daily fluid consumption.

http://www.rice.edu/~jenky/sports/caffeine.html

Caffeine and Athletic Performance

Despite considerable research in this area, the role of caffeine as a performance enhancing drug is still controversial. Some of the data are conflicting, which is in part due to how the experimental studies were designed and what methods were used. However, there is general agreement in a few areas:

1. Caffeine does not appear to benefit short term, high intensity exercise (eg. sprinting)
2. Caffeine can enhance performance in endurance sports.

Glycogen is the principal fuel for muscles and exhaustion occurs when it is depleted. A secondary fuel, which is much more abundant, is fat. As long as there is still glycogen available, working muscles can utilize fat. Caffeine mobilizes fat stores and encourages working muscles to use fat as a fuel. This delays the depletion of muscle glycogen and allows for a prolongation of exercise. The critical time period in glycogen sparing appears to occur during the first 15 minutes of exercise, where caffeine has been shown to decrease glycogen utilization by as much as 50%. Glycogen saved at the beginning is thus available during the later stages of exercise. Although the exact method by which caffeine does this is still unclear, caffeine caused sparing in all of the human studies where muscle glycogen levels were measured. The effect on performance, which was observed in most experimental studies, was that subjects were able to exercise longer until exhaustion occurred.

In addition to the beneficial effects on muscle, caffeine may alter the perception of how hard you are working. During testing, athletes are asked to judge their effort, which is referred to as the rating of perceived exertion (RPE). Some studies have yielded significantly lower RPE's -- less fatigue -- when the athlete used caffeine. Other studies have not found this effect. Obviously, the RPE is very subjective, and there are many things that may influence it.

What about caffeine in Ironman races?

The exercise studies on caffeine involved endurance testing of approximately 2 hours, so there is no specific information related to ultra-endurance races. Pre-race caffeine may be beneficial though, because the longer the race, the more important fat is as a fuel. During the race, caffeinated soft drinks are one of the choices at the aid stations in an Ironman. Whether this source of caffeine is useful is unknown, but these soft-drinks do supply necessary carbohydrate. Because longer races have a greater baseline risk of dehydration, nausea and abdominal cramps, it is very important to consider the side effects of caffeine (below).

Former Coke addict considering a relapse.