Thanks for a great article titled “Good brain food.” I have one question though concerning the following statement:
Research on caffeine consumption during exercise indicates the 1.5 mg/kg of body weight improves performance.
Is that per hour or what time frame? I weigh 87 kg, so is that 130 mg/hr?
Charlotte, NCHi MP,
Thanks for your question. While many cyclists and other endurance athletes may consume a moderate caffeine dose about one hour before exercise, consuming some caffeine during exercise, especially in the later part of a long training ride or race is not uncommon. While flattened cola was the most popular product consumed late in a race, caffeinated gels have opened up the choices available for caffeine consumption during exercise.
One study in particular (Cox, G. et al, J. Appl. Physiol. 93, 2002) measured the performance effects of several caffeine protocols around exercise. The exercise test protocol included two hours of steady state cycling at 70 percent peak oxygen uptake, followed by a time trial lasting under 30 minutes. Various caffeine protocols were used, including 6 doses of 1 mg caffeine per kg of body weight (about 420 milligrams total for a 70 kg cyclist) during the 120 minutes of steady state cycling. Another protocol had the subjects ingest 5 ml/kg of cola, twice during the 120 minutes of cycling, with the average caffeine intake being 94 mg. The researchers concluded that the ingestion of a small amount of caffeine at 1.5 mg/kg weight can improve performance. Note that this was over a two hour period.
It is important to note that the low dose of caffeine improved performance as did the high dose of caffeine-so more is not necessarily better. In fact when it comes to caffeine intake before exercise, moderate doses are just affective as well. Current recommendations are to consume about 6 mg/kg body weight- or about 300 to 500 mg if you plan to take in caffeine before exercise. You likely will do just as well with the lower dose, as with the higher dose, and not experience any potential side effects such as jitteriness. If you want to consume caffeine during exercise, aim for a total amount of 1.5 to 3.0 mg/kg body weight to be consumed over a ride lasting over two hours. At an hourly rate of 1.5 mg/kg or 130 mg for your current weight, this would be a fairly high dose of caffeine to consume per hour. Just as with caffeine consumption during exercise, you could experience some side effects such as jitteriness, or GI upset. So keep your dose moderate, particularly if you consumed some caffeine before the ride. Caffeine’s effects peak within 45 to 60 minutes of ingestion and it has a half-life (meaning it still has some effect) for 4 to 6 hours. If you plan to ride or race over four hours, taking some caffeine closer to the end of the ride would be helpful, and as research is indicating, particularly for a brain boost. Many gels have anywhere from 20 to 50 milligrams of caffeine per packet, though some are now supercharged with caffeine, while 12 ounces of cola provides about 40-50 milligrams.
I don’t recall if you have addressed this question, but is there any benefit to utilizing L-glutamine as a dietary supplement? In particular, would this be of any benefit in slowing the aging related sarcopenia (muscle loss)? Is there any dietary strategy for addressing this?
Phoenix, ArizonaHi Bob,
As you are aware, glutamine is an amino acid used as a nutritional supplement by athletes to maintain or build muscle protein levels during periods of intensive training. It is also promoted for use during hard training cycles in order to maintain or boost immune.
Glutamine has been studied for several reasons. Glutamine is an important source of fuel for immune system cells. In the early 1990’s studies found that lowered plasma glutamine levels were a marker for overtraining and fatigue in athletes. Researchers are not sure what this association truly reflects, and one recent study from Australia (Kargotich, et al, Int J Sports Med, 2007 28(3): 211-216) found that 6 weeks of progressive endurance training steadily increase plasma glutamine levels. As of now, there is conflicting evidence whether or not supplementing with glutamine can prevent or lessen this potential decrease in blood glutamine levels.
Of course, glutamine also plays a major role in protein metabolism, including protein synthesis and breakdown. Several studies have looked at glutamine supplementation in conjunction with a resistance training program. One recent study (Lehmkuhl et al. J Strength Cond Res, 2003, 17 (3): 425-438) had 29 male and female collegiate track and field athletes take 4 g of glutamine daily along with creatine. This supplement combination was compared to creatine alone. Their results indicated that creatine supplementation in conjunction with resistance training was associated with in an increase in cycling power and an increase in lean body mass. But the addition of glutamine did not further enhance these increases. Another study examined the effects of whey protein supplementation on body composition, muscular strength, and muscular endurance during 10 weeks of resistance training. There were three supplement procotols, one of which included 40 g whey protein+ 3 gm branched chain amino acids + 5 g glutamine. All groups had gains in muscle strength (as you would expect when following a 10 week strength training program), but the greatest gain in lean body mass was seen with 40 g whey protein + 8 g casein.
We do also know that ingesting anywhere from 7 to 20 g (0.1 to 0.3 g/kg) of glutamine daily for several weeks shows no clinical toxicity. Larger doses ranging from 0.3 to 0.6 g/kg body weight can be taken for 5 days with no adverse effects in normal subjects.
However, to make the most of your resistance training efforts and to offset the loss in muscle mass that is part of the normal aging process, the following nutritional guidelines are recommended:
Consuming enough calories to build muscle. Consuming enough carbohydrate to meet the glycogen fuel demands of both cycling training and resistance training. Having enough protein in your daily diet. Consuming 15 to 25 g of high quality protein, such as whey, casein, or soy, or an animal protein sources (poultry, egg whites, fish) within one hour before weight training. This should be combined with 25 g of carbohydrate, more if you will follow the weight training session with an aerobic workout. After resistance training consume 15 to 25 g of high quality protein combined with 25-50 g of carbohydrate. This can be consumed from regular high protein foods and carbohydrate sources. Use supplements before or after the weight training session for optimal timing and convenience depending on your training and meal schedule, and food preferences.
Monique Ryan, MS, RD, LDN is a nationally recognized nutritionistwith over twenty-two years of experience and is owner of Personal NutritionDesigns, a Chicago based nutrition consulting company that provides nutritionprograms for endurance athletes across North America (www.moniqueryan.com).Monique consults with the Chicago Fire Soccer Team, and was the nutritionistfor Saturn Cycling from 1994 to 2000. She has also consulted with the Volvo-CannondaleMountain Bike Team, the Gary Fisher Mountain Bike Team, and the RollerbladeRacing Team. Monique has consulted with USA Cycling, and was a member ofthe Performance Enhancement Team for the Women’s Road Team leading to the2004 Athens Olympics. She has also provided nutrition consultation servicesto USA Triathlon for coaching clinics, athlete clinics, and for the residentathlete team and was a member of the USAT Performance Enhancement Teamfor the 2004 Athens Olympics. Monique is the author of “SportsNutrition for Endurance Athletes,” 2nd edition (March 2007), from VeloPress,which provides sports specific nutrition for road cycling, mountain biking,running, triathlon, swimming, rowing, and adventure racing. She is alsoauthor of “PerformanceNutrition for Winter Sports” (PeakSports Press), “Performance Nutritionfor Team Sports” (PeakSports Press), and “Complete Guide to Sports Nutrition.”Monique is a regular contributor to VeloNews, Inside Triathlon,Outside, and ACE Fitness Matters. As part of the FeedZonecolumn, Monique will answer selected questions online. Please sendyour questions to RyanWebQA@aol.com.