NEW SITE ----> Go to http://www.miketnelson.com < -----for all my latest info a this site below is from about 5-8 years ago. Michael T Nelson, MS CSCS, RKC is a PhD
Candidate in Kinesiology (Exercise Physiology) at the U of MN and Fitness Consultant in White Bear Lake, MN. Ramblings here about research, training, nutrition, exercise phys, Z Health, joint mobility, and whatever else I want
Greetings! Just a quick update on a new study below.\
I will be having dinner with my good friend "The Movement Doctor" tonight, so I am super excited to learn lots of new stuff. Check out her website below
RosserJI, Walsh B, Hogan MC. University of California - San Diego.
The purpose of the present study was to determine whether exposure to exogenous physiological concentrations of caffeine influence contractility, Ca(2+) handling, and fatigue development in isolated single Xenopuslaevis skeletal muscle fibers. After isolation, two identical contractile periods (separated by 60 min rest) were conducted in each single myofiber (n=8) at 20 degrees C. During the first contractile period, four fibers were perfused with a non-caffeinated Ringer's solution, while the other four fibers were perfused with a caffeinated (70 microM) Ringer's solution.
The order was reversed for the second contractile period. The single myofibers were stimulated during each contractile period at increasing frequencies (0.16, 0.20, 0.25, 0.33, 0.50, and 1.0 tetanic contractions/second) with each stimulation frequency lasting 2 minutes until fatigue ensued, defined in this study as a fall in tension development to 66% of maximum. Tension development and free cytosolic [Ca(2+)] (fura-2 fluorescence spectroscopy) were simultaneously measured. There was no significant difference in the peak force generation, time to fatigue, cytosolic Ca(2+) levels, or relaxation times between the non-caffeinated and caffeinated trials.
CONCLUSION: These results demonstrate that physiological levels of caffeine have no significant effect on Xenopus single myofibercontractility, Ca(2+) handling, and fatigue development and suggest that that any ergogenic effects of physiological levels of caffeine on muscle performance during contractions of moderate-to-high intensity are likely related to factors extraneous to the muscle fiber.
My Notes: While readers of this blog will be quick to point out that this was a highly isolated study done in a dish, the cool part is that you can isolate some interesting things. Having said that, this is a very crude study and I am scratching my head at what was novel here? How is this new in 2009? For those that are wondering, it is a type of frog; although classically many of the early experiments on the neuromuscular junction (NMJ) were done in a similar set up. Heck, I took a whole class where we did this and the crazy set up to the experiment may take you 2-3 hours BEFORE you measure anything.
The newer researcher shows that the main effect of caffeine is central nervous system related (CNS). I am still amazed at how much we don't know about the mechanisms of caffeine, even though it has been studied for quite some time.
Make It Easy Here is the tip of the day based on a conversation I had with Frankie Faires awhile back.
Your goal in the gym is to make what you are doing look easy.
Your goal is NOT to make tons of noise, grunt, tighten your neck and have a few veins burst in your head. If that happens as a by product on occasion, I will let ya slide; but that is NOT the intended goal.
Watch elite athletes. Do they make it look hard or easy? If they make it look easy, why are YOU making it look hard?
How do you make it look easy? 1) It is easy (so get stronger or more coordinated or both)
2) Practice like it is easy.
Now, this does NOT mean bad form. Perfect form! Does grinding your teeth so hard that your eyes almost close help you lift more? Or is this a learned response from doing many reps that way? I would go with the latter.
Here is a great deadlift video. Notice the crap ton of weight on the bar, notice the focus, but does he make it look easy or hard? For those that are bad at math, it is 937 lbs!
Blog update on Nerve Flossing I did a post awhile back discussing how nerve flossing can increase range of motion, strength and ultimately performance (see below)
Tarnopolsky MA. Departments of Pediatrics and Medicine, McMaster University, Hamilton, ON L8N3Z5, Canada(e-mail: tarnopol@mcmaster.ca).
The ergogenic effect of caffeine on endurance exercise performance is multifactorial; however, there is evidence for an effect on both the central nervous system and the excitation-contraction coupling of skeletal muscle. The increase in exercise performance seen following intracerebroventrical caffeine injection in rats provides strong evidence for a central ergogenic effect. The central ergogenic effect is not likely related to the ability of caffeine to promote wakefulness, but could be due to an increase in the pain and effort perception threshold. There is no evidence that caffeine alters peripheral nerve conduction velocity or neuromuscular transmission, and 1 study showed that motor unit synchronization was not altered by caffeine. Studies have also shown that caffeine can have a direct effect on skeletal muscle that could be ergogenic.
For example, patients with high cervical spinal cord lesions showed improvements in stimulated contractile force during cycling, in spite of the fact that they have no peripheral pain input and no sympathetic nervous system response. Two studies have found a potentiation of force production during submaximal stimulation intensities, and 1 found that the M-wave amplitude was not altered by caffeine. Together, these studies suggest that caffeine can enhance contractile force during submaximal contractions by potentiating calcium release from the ryanodine receptor, not by altering sarcoplasmic excitability. Furthermore, the potentiation of force during submaximal electrical stimulation is identical in habitual and nonhabitual caffeine consumers.
Conclusion: In summary, the ergogenic effects of caffeine during endurance activity are mediated partly by enhanced contractile force and partly by a reduction in perceived exertion, possibly though a blunting of effort and (or) pain.
My Notes: Endurance training at a high level is all about "pain management". While I believe that pain is very ergolytic (pain decreases performance), caffeine use may be a way to enhance endurance performance.
Like all things, if you do decide to try it out, pure anhydrous caffeine (No Doze) is the best way to go since you want to standardize the caffeine amount. Make sure you do in practice a few times and NOT before a big race!! Practice makes perfect.
Slivka D, Hailes W, Cuddy J, Ruby B. Montana Center for Work Physiology and Exercise Metabolism (WPEM), Department of Health and Human Performance, The University of Montana, 32 Campus Drive, Missoula, MT 59812, USA.
The ingestion of carbohydrate (+CHO) and caffeine (+CAF) during exercise is a commonly used ergogenic practice. Investigations are typically conducted with subjects who are in a rested state after an overnight fast. However, this state of positive energy balance is not achieved during many work and exercise circumstances. The aim of this study was to evaluate the substrate use and performance effects of caffeine and carbohydrate consumed alone and in combination while participants were in negative energy balance.
Male participants (n = 9; 23 +/- 3 years; 74.1 +/- 10.6 kg) completed 4 trials in random order: -CAF/-CHO, -CAF/+CHO, +CAF/-CHO, and +CAF/+CHO. Diet and exercise were prescribed for 2 days before each trial to ensure negative energy balance. For each trial, before and after 2 h of cycling at 50% of maximal watts, a saliva sample and a muscle biopsy (vastuslateralis) were obtained. A simulated 20 km time trial was then performed.
The respiratory exchange ratio was higher (p <> 0.05), or any of the other trials. When co-ingested with carbohydrate, caffeine increased fat use and decreased nonmuscle glycogen carbohydrate use over carbohydrate alone when participants are in negative energy balance.
Conclusion: When co-ingested with carbohydrate, caffeine increased fat use and decreased nonmuscle glycogen carbohydrate use over carbohydrate alone when participants are in negative energy balance;However, caffeine had no effect on the 20 km cycling time trial performance.
My Notes: The use of burning more fat for fuel is referred to as the "Randle effect" The more technical definition is the inhibition of the oxidation of glucose by an excess of fatty acids. It appears that this study would confirm that caffeine does increase the use of fatty acids as fuel, but I am not convinced yet. If this is true, why was it not show in the caffeine but no carbs group? They pulled salivary cortisol levels, but did not report them in the abstract? Hmmmm.
If anyone wants more info on this one, drop me a note in the comments section and I may have to do some further investigation. Or if you have already done that, I really want to hear from you.
Welcome again and thanks for stopping by! This issue will not make me any friends with the supplement companies, but I stand by science; so off we go! See the full abstract below and my comments after that.
Hoffman JR, Kang J, Ratamess NA, Rashti SL, Tranchina CP, Faigenbaum AD. Department of Health and Exercise Science, The College of New Jersey, PO Box 7718, Ewing, New Jersey 08628, USA. hoffmanj@tcnj.edu.
ABSTRACT: BACKGROUND: The purpose of this study was to examine the acute effects of a weight loss supplement on resting oxygen uptake (VO2), respiratory quotient (RQ), caloric expenditure (kcal), heart rate (HR), and blood pressure (BP) in healthy and physically active individuals.
METHODS: Ten subjects (5 male, 5 female; 20.2 +/- 1.2 y; 172.2 +/- 8.9 cm; 71.5 +/- 17.2 kg; 17.3 +/- 2.6% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. During each session, subjects reported to the Human Performance Laboratory after at least 3-h post-absorptive state and were provided either 3 capsules of the weight loss supplement (SUP), commercially marketed as Meltdown(R) or 3 capsules of a placebo (P). Subjects then rested in a semi-recumbent position for three hours. VO2 and HR were determined every 5 min during the first 30 min and every 10 min during the next 150 min. BP was determined every 15 min during the first 30 min and every 30 min thereafter. The profile of mood states was assessed every 30 min.
RESULTS: Area under the curve analysis revealed a significant 28.9% difference in VO2 between SUP and P for the three hour study period. In addition, a significant difference in energy expenditure was also seen between SUP (1.28 +/- 0.33 kcal.min-1) and P (1.00 +/- 0.32 kcal.min-1). A trend (p = 0.06) towards a greater utilization of stored fat as an energy source was also demonstrated (0.78 +/- 0.23 kcal.min-1 and 0.50 +/- 0.38 kcal.min-1 in P and SUP, respectively). Significant elevations in HR were seen during hours two and three of the study, and significantly higher average systolic BP was observed between SUP (118.0 +/- 7.3 mmHg) and P (111.4 +/- 8.2 mmHg). No significant differences were seen in diastolic blood pressure at any time point. Significant increases in tension and confusion were seen in SUP. CONCLUSION: Results indicate a significant increase in energy expenditure in young, healthy individuals following an acute ingestion of a weight loss supplement. In addition, ingestion of this supplement appears modify mood and elevate HR and systolic BP following ingestion.
My Comments First off, I love that they actually sponsored real research and I do have to give them kudos for that as it is much more than most supplement companies do. So hats off on that part.
The big question is, does it work?
According to the study, it was significantly better at burning more calories. Keep in mind that when they say SIGNIFICANTLY they are talking about STATISTICAL significance and many times this adds up to a hill of beans in the really real world. "a significant difference in energy expenditure was also seen between SUP (1.28 +/- 0.33 kcal.min-1) and P (1.00 +/- 0.32 kcal.min-1)"
Er, what? They measured for 3 hours, so 1.28 X 180 minutes= 230 caloriescompared to 1.00 x 180 minutes = 180 calories. So over 3 hours you would burn a whole 50 more calories. Whoo ha. That would be about an 1/2 of a granola bar at best.
If you took that every day 2xs a day for a week you are at an extra 700 calories per week,so after 5 weeks you may burn an extra pound of fat (3,500 kcal) ASSUMING that this effect stays the same for that entire time (my guess is that it would not, but we don't know since this was an acute study). What is in it? Above is the ingredients. Holy freakin' stimulants batman!
Cost? I typed in an Internet search and found it a vitacost for about 34 clams without shipping and gives you 40 servings (3 caps a serving). So at 2 servings per day (6 caps), it will last about 3 weeks. To get to 5 weeks you will need just under 2 bottles and you will be out about $70
My rough math says that at best, 1 pound of fat will cost you $70 and 5 weeks of your time.
Personally, I can find many ways to spend a 70 clams and my first would be to buy a session with a fitness professional and put it towards a kettlebell!
So, does work? I guess so, but the amount adds up to pretty much nothing; so I will give it a thumbs down for now.
Add to this that I would never personally take stimulants for that long a period of time either. I can just hear my adrenal glands start to shrink.
In the end it is a free country and each person has to make a decision for themselves. I just ask that they look at some science first and at least there is some science to investigate here.
The use of burning more fat for fuel is referred to as the "Randle effect" The more technical definition is the inhibition of the oxidation of glucose by an excess of fatty acids.
What?
The theory goes that caffeine should increase the LIBERATION of fat (e.g pulling those pesky fats out of their comfy home in the fat cell). In order to BURN fat, you first most get it into the blood stream.
However, I am not convinced that liberation of fat is the limiting step, I think BURNING fat is more limiting.
How does this help me loose my muffin top? In short, I am not convinced that caffeine by itself is all that helpful to deflate your spare tire and shrink your muffin top. My recommendation is find a local fitness professuional (hey, I know a good one in White Bear Lake MN, shameless I know) to get you on the right track. Some Precision Nutrition, Z Health and Kettlebells make a killer combination!
Graham TE, Battram DS, Dela F, El-Sohemy A, Thong FS. Human Health and Nutritional Sciences, University of Guelph, Guelph, ON N1G2W1, Canada.
Caffeine, an adenosine receptor antagonist, has been studied for decades as a putative ergogenic aid. In the past 2 decades, the information has overwhelmingly demonstrated that it indeed is a powerful ergogenic aid, and frequently theories have been proposed that this is due to alterations in fat and carbohydrate metabolism. While caffeine certainly mobilizes fatty acids from adipose tissue, rarely have measures of the respiratory exchange ratio indicated an increase in fat oxidation. However, this is a difficult measure to perform accurately during exercise, and small changes could be physiologically important.
The few studies examining human muscle metabolism directly have also supported the fact that there is no change in fat or carbohydrate metabolism, but these usually have had a small sample size. We combined the data from muscle biopsy analyses of several similar studies to generate a sample size of 16-44, depending on the measure.
We examined muscle glycogen, citrate, acetyl-CoA, glucose-6-phosphate, and cyclic adenosine monophosphate (cAMP) in resting samples and in those obtained after 10-15 min of exercise at 70%-85% maximal oxygen consumption. Exercise decreased (p < style="font-weight: bold;">
Conclusion:There is very little evidence to support the hypothesis that caffeine has ergogenic effects as a result of enhanced fat oxidation. Individuals may however, respond differently to the effects of caffeine, and there is growing evidence that this could be explained by common genetic variations.
Below is an excellent review of caffeine on athletic performance done by Ryan Gage. Ryan is graduating soon here from the University of Minnesota and his bio is at the end.
Special thanks to Ryan for contributing this great review to the blog. Much appreciated!
The Effects of Caffeine on Physical Activity and Athletic Performance
Completed by Ryan Gage
Introduction
Caffeine, a central nervous system and cardiac stimulant, is the most popular and most readily available drug in the world (Bramstedt 2007). Athletes of all ages and abilities are exposed to caffeine on a regular basis and make a choice of whether or not to use the drug. Many athletes, regardless of age or ability, do not know the specifics of the drug in relation to the physiology and biochemistry of their bodies. This lack of knowledge can hinder performance in some cases, and lead to serious illness or injury in others.
There are many aspects of fitness including cardiorespiratory endurance, muscular strength, muscular endurance, flexibility, and body composition. The effects of caffeine ingestion related to these aspects of fitness have been documented in research studies. However, many studies are restricted to a small population with a specific gender, degree of athletic ability, and socio-economic status. In order for an athlete to understand the effects of caffeine on their particular body they must find studies performed on populations similar to his or her particular gender, age, and athletic ability.
Through careful analysis of current research, caffeine has been positively correlated to benefit athletic performance in regards to upper body strength and endurance, cardiorespiratory endurance, hydration, thermoregulation, and mental concentration. Countless sports are highly dependent on the previously stated characteristics of physical performance. Upper body strength and endurance plays a large role in football, baseball, lacrosse, swimming, and basketball.Cardiorespiratory endurance, hydration, thermoregulation, and mental concentration are cornerstones of track and field, Nordic skiing, and cycling, amongst many other sports. With that being said, caffeine supplementation in a regulated amount, such as mg of caffeine per kg of body weight, will enhance athletic performance. In today’s athletic competition, winners and losers are determined by fractions of a second. Even if caffeine’s effects are miniscule in comparison to illegal drugs such as EPO and steroids, the small difference may be enough to push an athlete just enough to win a competition they otherwise would not have.
Review of Literature
As a central nervous system and cardiac stimulant caffeine is easily tied to cardiovascular athletic performance.However, the link relating caffeine’s effects to resistance training is less obvious. Beck, Housh, Schmidt, Johnson, Coburn, and Malek (2006) concluded that a supplement containing caffeine allowed participants to increase upper body strength as determined by a one-repetition maximum (1RM) bench press. Thirty-seven men with a mean age of 21 participated in the study; all having previous resistance training experience. 48 hours following the subjects’ initial visits to the laboratory where they performed the baseline 1RM bench press they returned and were randomly assigned to a caffeine supplement group or a placebo group. After ingesting the caffeine or placebo pill the participants waited one hour before retesting his 1RM bench press. There was a significant (p<0.05) style="">
Astorino, Rohmann, and Firth (2007) provide further validation of caffeine positively affecting upper body strength and endurance in a study consisting of 22 resistance trained men with a mean age of 23.4, ranging from 18 to 29 years old. Previous resistance training experience of at least two total-body workouts a week was a prerequisite for participating in the study.The men’s previous training history ranged from 1.5 years to 12 years, with a mean of 6 years. Prior to testing the participants were required to have no caffeine intake for 48 hours and refrain from exercise for 24 hours immediately before visiting the laboratory. During the first visit to the laboratory the participants were given either a 6 mg/kg dose of caffeine or the placebo and then performed a 1RM bench press. Immediately following the 1RM test, 60% of the 1RM was placed on the bar and the participants pressed that weight until complete failure as a means of measuring muscular endurance. Even though statistically insignificant (p>0.05), an increase in muscular endurance (11-12%) was shown in the participants who ingested the caffeine supplement when compared to those who ingested the placebo.
Many studies investigating the relationship between caffeine and exercise use pharmaceutical caffeine in capsules. However, Forbes, Candow, Little, Magnus, and Chilibeck (2007)examined the effects of Red Bull Energy Drink on exercising participants performing three sets of bench press to determine muscular endurance. This study also differed from others investigating caffeine and muscular strength or endurance in the fact that it included women. 11 men and 4 women who are physically active two to three days a week were selected for the study. Subjects were randomly assigned to ingest Red Bull at 2 mg/kg or placebo 60 minutes prior to performing the bench press endurance test. One week after the initial testing the participants revisited the laboratory and ingested the opposite supplement. After determining the participants’ 1RM on the bench press they were instructed to complete three sets of bench press repetitions to complete fatigue. The weight used for the trials was 70% of the participants’ 1RM, and the trails were separated by a one-minute rest period. There was a significant increase in the number of repetitions achieved over the three sets by those who ingested Red Bull (34 ± 9) versus the placebo (32 ± 8).
Caffeine is not only a cardiac stimulant, but also a central nervous system stimulant as well. The central nervous system controls cognitive functions that are essential to athletic performance.
McLellan, Kamimori, Voss, Tate, and Smith (2007)hypothesized that soldiers who received a dose of caffeine during overnight periods of no sleep would physically and cognitively function better in the morning hours when compared to soldiers given a placebo. Twenty male Special Forces soldiers with a mean age of 28.6 and a mean body mass of 81.2 kg participated in the study. The soldiers were randomly separated into groups of four. Two soldiers within each group received caffeine, while the other two soldiers received the placebo. Instead of using caffeine supplemented in a pill form, the soldiers were given pieces of Stay Alert caffeine gum with 100 mg of caffeine in each piece. The placebo pieces of gum matched Stay Alert in taste, color, and texture. McLellan et al. opted to use gum instead of pills for this study because it is shown that the caffeine in the gum is more quickly absorbed into circulation. The soldiers’ physical skills were assessed through an obstacle course run and marksmanship, while cognitive skills were assessed in analyzing their communication and vigilance. The vigilance test consisted of soldiers sitting 175-200 meters away from a building. The soldiers were then asked to record the “where, when, and what” of any activity that occurred in their field of vision. The caffeine group maintained vigilance at a mean of 60.2%, while the placebo group scored only a mean of 33.6% in the vigilance tests. McLellan et al. suggests that the use of 800 mg of caffeine given throughout overnight periods maintained cognitive alertness and vigilance better than the placebo group. However, the physical obstacle course test did not show significant differences between the two groups.
As with any other drug used for performance enhancement caffeine has a perceived benefit to many athletes. Desbrow and Leveritt (2007)investigated the perceptions, knowledge, and experiences of caffeine use by competitors in the 2005 Ironman Triathlon World Championships. 105 men and 35 women from both the elite and age-group levels of competitor participated in the study. The mean length of experience competing in triathlons was 10.2 ± 7 years. The participants were required to complete a questionnaire exploring his or her knowledge, attitudes, use history, planned consumption, and caffeine-related side effects. The athletes’ attitudes regarding caffeine use included the effect of caffeine on endurance, speed, power, strength, concentration, and fat loss. The section of the questionnaire regarding the athletes’ knowledge of caffeine sources included categorizing foods and beverages into groups of “contains no caffeine,” “contains caffeine but only a small amount,” or “contains caffeine in a larger amount.” Finally, the athletes were asked to provide information regarding the dosage they would consume if they wanted to improve their Ironman triathlon performance and the severity of common side effects related to caffeine consumption, such as tremors, shakes, headaches, elevated heart rate, and abdominal discomfort. Through statistical analysis, Desbrow and Leveritt (2007) concluded that it is the perception of the 2005 Ironman Triathlon participants that caffeine is ergogenic to their performance. The athletes were able to identify sources of caffeine in mainstream products such as coffee, tea, cola, and energy drinks, but were not accurate in their ability to quantify the amount of caffeine in those products. The top three ways of obtaining knowledge regarding information on caffeine’s effectiveness were self-research/experimentation, fellow athletes, and magazine articles.
Caffeine’s physical effects on exercise are well documented; however, a relationship between caffeine and the mental aspect of exercise is less studied. As heart rate is a physical measure of exercise intensity a rating of perceived exertion (RPE) is a subjective mental measure of exercise intensity. Ahrens, Lloyd, and Walker (2006) investigated the relationship between caffeine and cardiorespiratory fitness in women, with RPE being one of the criterions to determine the results. 20 women ranging in age from 19 to 28 participated in the study. The women were of average fitness level and were not habitual caffeine users. The women participated in three trials of stead-state treadmill walking at 3.5mph. The three trials consisted of each woman being randomly assigned a 3-mg/kg caffeine, 6-mg/kg caffeine, or placebo dosage. Test subjects made four separate visits to the laboratory, two to seven days apart. During each visit the subject participated in an eight minute walk at 3.5mph exactly one hour after ingesting the given capsule. Analysis of data determined that RPE was not significantly different between the 3-mg/kg caffeine, 6-mg/kg caffeine, or placebo dosages. The results led Ahrens et al. to state “it would not be prudent for a trainer to recommend caffeine in order to increase a woman’s energy expenditure or to decrease perception of effort during mild exercise. Caffeine intake should not interfere with monitoring walking intensity by tracking exercise heart rate in women.”
Ahrens et al. (2006) gives insight into how caffeine would affect cardiorespiratory training in a low intensity setting as the subjects were not pushed past a 3.5mph pace. Contrarily, McClaran and Wetter (2007) performed tests that pushed the participants to absolute exhaustion on a cycle ergometer. The nine male subjects that participated in the study were randomly assigned to perform the bicycle test after ingesting 1.5 mg/kg caffeine, 3.0 mg/kg caffeine, or a placebo. The participants took part in three separate tests so that they could be given all three variations in the supplement prior to performing the test. As most studies previously stated, there was a one hour time period between the participants ingesting the given supplement and performing the test. However, in the study performed by McClaran and Wetter (2007) the subjects were only allowed to rest for thirty minutes prior to partaking in the cycle test. The subjects endured three separate warm-up sessions of 60 watts, 120 watts, and 180 watts, with each session lasting five minutes. After receiving a two-minute rest off of the bike the subjects once again cycled at 180 watts for one minute, which was then increased 30 watts every minute until complete exhaustion. Measurements taken during the tests included heart rate, systolic blood pressure, tidal volume of breathing, rating of perceived exertion, and oxygen consumption (VO2). After analyzing the data McClaran and Wetter (2007) concluded that caffeine doses of 1.5 mg/kg and 3.0 mg/kg of body weight significantly lowered heart rate during the submaximal testing, ranging from four to seven beats per minute lower. However, the heart rates were not found to be lower as the participant’s gave their maximal effort in the exhaustion phase of the test. Also, McClaran and Wetter (2007) stated that neither dose of caffeine had any effect on blood pressure during the exercise portion of the test. Further validation of the findings in Ahrens et al. (2006) were provided as McClaran and Wetter (2007) stated that caffeine had no effect on the subject’s rating of perceived exertion during the test.
In a similar manner to the study performed by Forbes et al. (2007) in which the widely available product Red Bull Energy Drink was used as the supplement in the study Roberts, Taylor, Wismann, Wilborn, Kreider, and Willoughby (2007) used JavaFit Energy Extreme coffee as the supplement provided to test subjects. JavaFit Energy Extreme coffee is described as “a functional gourmet coffee that contains a proprietary blend of caffeine, garcinia cambogia, chromium polynicotinate, and aurantium” and claims to increase energy expenditure. In hopes of determining if the claim of increased energy expenditure was valid, Roberts et al. (2007) goal for the study was to determine if post-exercise fat metabolism was enhanced by use of JavaFit Energy Extreme coffee. Study participants performed baseline testing in a graded treadmill test to determine peak VO2 and also a Wingate test for peak power. Three to four days following the baseline testing the subjects returned and went through the same testing after ingesting 354 mL of JavaFit Energy Extreme coffee or decaffeinated coffee. One week after the first round of testing the participants returned to the laboratory where they once again performed the graded treadmill test and Wingate test, but after consuming the remaining type of coffee. Roberts et al. (2007) discovered that JavaFit Energy Extreme coffee significantly increased VO2 readings three minutes after the exercise stopped when compared to baseline readings. The increase post-exercise VO2 led Roberts et al. to state that enhanced post-exercise fat metabolism may be obtained by consuming JavaFit Energy Extreme coffee prior to aerobic exercise.
An athlete’s hydration level can be the determining factor if he or she performs up to their greatest potential. Millard-Stafford, Cureton, Wingo, Trilk, Warren, and Buyckx(2007)investigated the affect a caffeinated sports drink had on the fluid delivery and hydration process during exercise. The conditions of the experiment were warm and humid, with a temperature of 28.5* Celsius (83.3* Fahrenheit) and 60% relative humidity at an indoor environmental chamber. A group of 16 highly trained male cyclist participated in the study. The cyclists performed three tests, separated by at least five days rest. They were given the carbohydrate-electrolyte drink Gatorade for one test, Gatorade with caffeine for one test, and a placebo for the remaining test. The cycling test included two portions. First the cyclist would perform two hours of steady state cycling at 60%-75% of their VO2max. After completing the initial two hours of cycling the subjects immediately performed a 15-minute maximal effort ride. Prior to performing the two-hour ride the cyclist drank 6mL/kg body weight of the selected beverage for that day. During the experiment the subjects were given 3mL/kg body weight of the beverage at 15-minute intervals. For those ingesting the caffeinated beverage the caffeine was given at a volume of 5.3 mg/kg body weight. Millard-Stafford et al. (2007) measured the sweat rate, urine output, and fluid retention of each participant to determine his hydration level throughout the test. As there were no significant differences found among the three types of beverages administered Millard-Saffort et al. (2007) concluded that a caffeinated carbohydrate-electrolyte sustains hydration and thermoregulatory function as well as a normal carbohydrate-electrolyte drink. Even though caffeine is considered a diuretic the effects are not shown when it is consumed during exercise.
Discussion
The research studies discussed investigated the effect of caffeine on different areas of fitness such as cardiorespiratory endurance, muscular strength, power, and endurance, and mental concentration. The studies were designed in such a way that they measured only one particular area of fitness at a time. Even though the studies differed in purpose and design there were common themes throughout that collectively limited the studies. The first common theme throughout the studies is that they all used a small number of participants. On average, the researchers limited the number of participants to 10-20. Alsofurther limiting the results of some studies was the use of only males or females. Studies conducted by Millard-Safford et al. (2007), McClaran and Wetter (2007), Ahrens et al. (2006), McLellan et al. (2007), and Astorino et al. (2007) only used one gender of participants. By only including a very distinct population in the studies the results are only applicable to a small group of people. In many instances only middle-aged males will receive information regarding how caffeine affects their performance in the athletic world.
Another limiting factor in the research is regarding the length of the studies performed. Many of the studies including Astorino et. al. (2007), Roberts et al. (2007), Ahrens et al. (2006), Beck et al. (2006), and Forbes et al. (2007) investigated the acute effects of caffeine on exercise. The participants in these studies would go to the laboratory, ingest caffeine or placebo, and perform the given exercise within one and a half hours after ingestion. The design of these studies would then send the participant home, and only see them once more as they were tested for the remaining dosage (caffeine or placebo). The design of these studies limits the available knowledge regarding the long-term effects of caffeine and exercise. Granted availability of both researchers and participants for a chronic caffeine prior to exercise study would be difficult, the results would be interesting.
A final limiting factor in the research was ethically how much caffeine the participants could be given. Roberts et al. (2007) limited the pre-exercise caffeine consumption to 354 ml of coffee. Forbes et al. only gave the participants 2 mg/kg body mass of caffeine. Ahrens et al. (2006) and Astorino et al. (2007) did give an increased amount of 6 mg/kg body mass, yet this amount of caffeine has been shown to be a safe level of caffeine. A research approval board would not allow participants to be given such a large amount of caffeine that could possibly have detrimental health effects. However, in reality athletes do not measure their caffeine consumption by the mg per kg of body mass, and may have taken far greater amounts of caffeine prior to exercise so the research would be interesting to see how higher levels of caffeine affected performance.
As a certified personal trainer the knowledge obtained through this research has a very practical application. The improvements that caffeine gives athletes would also be beneficial to the less elite average personal training client. The increase in VO2max and possible post-exercise fat metabolism as described by Roberts et al. (2007) would give the greatest benefit as many clients are overweight and looking for any advantage that they can obtain in their fight against obesity. Additionally, the correlation between pre-exercise ingestion of caffeine and increase in muscular strength would be beneficial for the vast number of clients in a more strength and conditioning aspect.
Unfortunately, accompanying the many benefits that are associated with caffeine and exercise are ethical issues regarding the possibility of adverse side effects that a client could experience. Unlike a controlled laboratory setting, a personal trainer would not be able to account for many of the variables that researchers are able to eliminate. For instance, researchers often used pharmaceutical grade caffeine that was precisely measured. The average personal trainer and their client would not likely have the money or means of obtaining pharmaceutical grade caffeine and would settle for other forms of caffeine such as coffee, soda, or supplements, which could do more harm than good. Supplements are not regulated by the Food and Drug Administration, thus leaving both the training and client wondering if the amount of caffeine on the label is actually the amount in the supplement. Additionally, the carbonation in many beverages like soda and energy drinks would affect the client’s physiology during exercise. With all of these variables to account for the practice of a personal trainer telling a client to ingest caffeine prior to exercise may be risky. Without proper equipment to detect and monitor certain cardiac functions throughout exercise many personal trainers should not be willing to risk their certification and a possible lawsuit if there were an adverse side affect related to the caffeine consumption.
Future research regarding the effect of caffeine on athletic performance should attempt to lessen some of the limitations of the current research studies. For starters, the participants of future studies should be larger in number and more diverse in age and gender. In order to perform similar tests such as a cycle ergometer, graded treadmill tests, or maximum bench presses on a large number of people the process could be both costly and time consuming.However, the valuable information received from such a large study could be related to a greater number of people. Also, the larger studies should test males and females side by side for ease of comparison. Forbes et al. (2007) and Roberts et al. (2007) did test males and females together in the same study, however, the number of males and females were uneven in the study performed by Forbes (11 male, 4 female) and the total number of participants in the study conducted by Roberts was very small (10). A large study consisting of both males and females at a relatively close ratio would eliminate the variables when comparing similar studies. Even if two studies had very similar methods and procedures the results cannot be accurately lumped into one general correlation. Factors such as the environment of the testing facility and attitude of the researchers can factor in to how the participant performs regardless of the methods and procedures of the studies.
Research performed using participants varying in age would also increase the knowledge regarding caffeine use during exercise. Studies conducted by Beck et al. (2006), Forbes et al. (2007), Roberts et al. (2007), and Ahrens et al. (2006) all used participants with an average age ranging from 20-29. This is a small window of people that use caffeine, exercise, or a combination of the two. Information regarding the use of caffeine on the changing metabolisms and physiologies of an aging population would be interesting to compare to the current studies focusing on a young to middle-aged healthy population.
Conclusion
A critical review of literature pertaining to the ingestion of caffeine prior to physical activities and athletics shows that caffeine does in fact have a positive effect on performance in some areas of fitness. Specifically, athletes participating in events that depend heavily on aerobic endurance, muscular strength and endurance, and/or sustained mental concentration could improve their performance by ingesting caffeine prior to an event. However, there is no dosage that is applicable to every athlete. Each athlete would need to relate the findings in of the research studies to themselves. A common theme from many of the research articles suggests that a dose equal to 3-6 mg/kg of the athlete’s body weight ingested 30-60 minutes prior to exercise would be most beneficial in enhancing performance. Even with that recommendation the athlete must weigh the risks versus the perceived benefits. Prior to combining caffeine with exercise the athlete should see a physician to ensure they do not have an underlying cardiovascular disease that could be aggravated by caffeine’s stimulus of the central nervous system and cardiorespiratory system. If the athlete experiences headaches, tremors, unnecessary nervousness, or tachycardia, they should immediately refrain from combining caffeine and exercise. Hopefully in the future athletes will be better educated on the subject of how caffeine affects the physiology of their exercising bodies.In doing so they will be able to more precisely determine the amount of caffeine that will be beneficial to their performance.
Ryan will graduate in May 2009 with a B.S. degree in Kinesiology, with an emphasis in exercise science. He is personal trainer, certified through the American Council on Exercise (ACE) and hopes to obtain a more advanced certification such as ACSM upon graduating. Ryan will always have passion for performance training athletes, but he hopes to broaden his health and fitness knowledge base and work in a clinical setting in the future.
Ahrens, J. N., Lloyd, L. K., & Walker, J. L. (2006). The physiological effects of caffeine in women during treadmill walking. The Journal of Strength and Conditioning Research, 21(1), 164-168.
Astorino, T. A., Rohmann, R. L., & Firth, K. (2007). Effect of caffeine ingestion on one-repetition maximum muscular strength. European Journal of Applied Physiology, 102, 127-132.
Beck, T. W., Housh, T. J., Schmidt, R. J., Johnson, G. O., Coburn, J. W., & Malek, M. H. (2006). The acute effects of a caffeine-containing supplement on strength, muscular endurance, and anaerobic capabilities. The Journal of Strength and Conditioning Research, 20(3), 506-510.
Bramstedt, K. A. (2007). Caffeine use by children: The quest for enhancement. Substance use & Misuse, 42, 1237-1251.
Desbrow, B., & Leveritt, M. (2007). Well-trained endurance athletes' knowledge, insight, and experience of caffeine use. International Journal of Sport Nutrition and Exercise Metabolism, 17, 328-339.
Forbes, S. C., Candow, D. G., Little, J. P., Magnus, C., & Chilibeck, P. D. (2007). Effect of red bull energy drink on repeated wingate cycle performance and bench-press muscle endurance. International Journal of Sport Nutrition and Exercise Metabolism, 17, 433-444.
McClaran, S. R., & Wetter, T. J. (2007). Low doses of caffeine reduce heart rate during submaximal cycle ergometry. Journal of International Society of Sports Nutrition, 4(11)
McLellan, T. M., Kamimori, G. H., Voss, D. M., Tate, C., & Smith, S. J. (2007). Caffeine effects on physical and cognitive performance during sustained operations. Aviation, Space, and Environmental Medicine, 78(9), 871-877.
Millard-Stafford, M. L., Cureton, K. J., Wingo, J. E., Trilk, J., Warren, G. L., & Buyckx, M. (2007). Hydration during exercise in warm, humid conditions: Effect of a caffeinated sports drink. International Journal of Sport Nutrition and Exercise Metabolism, 17, 163-177.
Roberts, M. D., Taylor, L. W., Wismann, J. A., Wilborn, C. D., Kreider, R. B., & Willoughby, D. S. (2007). Effects of ingesting JavaFit energy extreme functional coffee on aerobic and anaerobic fitness markers in recreationally-active coffee consumers. Journal of the Internation Society of Sports Nutrition, 4(25)
Ganio MS, Klau JF, Casa DJ, Armstrong LE, Maresh CM. Department of Kinesiology, Human Performance Laboratory, University of Connecticut, Storrs, Connecticut, USA.
Endurance athletes often ingest caffeine because of its reported ergogenic properties. Although there are a vast number of studies quantifying caffeine's effects, many research studies measure endurance performance using a time-to-exhaustion test (subjects exercise at a fixed intensity to volitional exhaustion). Time-to-exhaustion as a performance measure is not ideal because of the high degree of measurement variability between and within subjects. Also, we are unaware of any endurance sports in which individuals win by going a longer distance or for a longer amount of time than their competitors. Measuring performance with a time-trial test (set distance or time with best effort) has high reproducibility and is more applicable to sport. Therefore, the purpose of this review was to critically and objectively evaluate studies that have examined the effect of caffeine on time-trial endurance (>5 minutes) performance.
A literature search revealed 21 studies with a total of 33 identifiable caffeine treatments that measured endurance performance with a time-trial component. Each study was objectively analyzed with the Physiotherapy Evidence Database (PEDro) scale. The mean PEDro rating was 9.3 out of 10, indicating a high quality of research in this topic area. The mean improvement in performance with caffeine ingestion was 3.2 +/- 4.3%; however, this improvement was highly variable between studies (-0.3 to 17.3%). The high degree of variability may be dependent on a number of factors including ingestion timing, ingestion mode/vehicle, and subject habituation. Further research should seek to identify individual factors that mediate the large range of improvements observed with caffeine ingestion.
Conclusion: In conclusion, caffeine ingestion can be an effective ergogenic aid for endurance athletes when taken before and/or during exercise in moderate quantities (3-6 mg.kg body mass). Abstaining from caffeine at least 7 days before use will give the greatest chance of optimizing the ergogenic effect.
My Notes: Very interesting that they are mention the method of exercise time to exhaustion vs a time trial method (pick a distance and record the time taken to complete it).
The time trial method is more realistic as it more closely mimics athletic competiions, but there is most likely a greater learning effect as the subjects learn how to pace themselves better on the second trial vs the first. Some try to get around this by having them do the first trial and not count it; thus reducing some learning effect.
Either way, it shows once again that caffeine appears to help the cardio bunnies. More info later this week on caffeine and strength athletes.
Here is a video of a bunch of crazy Minnesota kiteboarders from the last trip to South Padre Texas at the end of Nov and early Dec. If you look closely around 2:22 you will see yours truly and Jodie enjoy a great post session beer (Shiner Bock, the local brew is great). The live action kicks in around 4 minute mark.
Special thanks to Randy for the video! Nothing better than a great day on the beach, some kiteboarding in great winds, sunlight and lots of great friends. Excellent times!
More research! I am behind on getting some cool studies out to all of you. If you have any questions at all, feel free to post them in the comments and I will try to get to them as soon as I can. I know many smart people read this blog, so I am interested in your thoughts or even just basic questions so that all of us can learn more.
Very cool study since caffeine in higher doses may have an analgesic (pain killing) effect. Adding aspirin may work via a similar mechanism also.
I remember "back in the day" some strength coaches promoting a baby aspirin before lifting for this effect and also so that it may thin your blood a bit for better oxygen delivery. I have not see any research on the latter and personally I am not a fan of blunting the pain response for strength training at all since pain is vital feedback--you want to know if you did something wrong!
The only time it may be worth trying is for very long distance events (tris, marathons) if you are doing it as a professional and your income depends on upon it. Even then I would highly recommend those athletes to try a higher dose of caffeine first IN TRAINING. Do NOT make ANY changes before a big race!
We know that pain negatively affects performance, so the theory behind the study is sound. The tricky part is that caffeine has many different physiologic effects in the body.
Interestingly, caffeine, aspirin (or acetaminophen aka Tylenol) is commonly found in over the counter headache medicine.
Department of Health, Human Performance, & Recreation, Baylor University, Waco, Texas, USA. Geoffrey_Hudson@baylor.edu
This study compared independent effects of caffeine and aspirin on muscular endurance (repetitions), heart rate (HR), perceived exertion (RPE), and perceived pain index (PPI) during light resistance training bouts performed to volitional failure. It was hypothesized that the hypoalgesic properties of these ergogenic aids would decrease pain perception and potentially result in enhanced performance.
College-aged men (n = 15) participated in a within-subjects, double-blind study with three independent, counterbalanced sessions wherein aspirin (10 mg x kg(-1)), caffeine (6 mg x kg(-1)), or matched placebo were ingested 1 hour before exercise, and RPE, HR, PPI, and repetitions (per set and total per exercise) were recorded at 100% of individual, predetermined, 12-repetition maximum for leg extensions (LE) and seated arm curls (AC). Repeated-measures analyses of variance were used for between-trial comparisons.
Caffeine resulted in significantly greater (p <>or= 5 repetitions) for total repetitions, with 53% exceeding the effect size (>or= 2 repetitions) for repetitions in set 1 with caffeine (vs. placebo). In AC, 53% (total repetitions) and 47% (set 1 repetitions) of participants exceeded effect sizes with caffeine (vs. placebo), with only 13% experiencing decrements in performance (total repetitions). Aspirin also produced a higher PPI and RPE overall and in set 1 (vs. placebo).
Conclusion: This study demonstrates that caffeine significantly enhanced resistance training performance in leg extensions and arm curls, whereas aspirin did not. Athletes may improve their resistance training performance by acute ingestion of caffeine. As with most ergogenic aids, our analyses indicate that individual responses vary greatly.
My notes: The caffeine dose used here is on the higher end and comes out to be about 600 mg for an adult male around my size (about 21o lbs), which is about 3-4 standard cups of coffee.
It showed that caffeine at this dose for this protocol did help performance.
Ironically, asprin INCREASED the percieved pain and RPE (rating of percieved effort--the weights felt heavier) which is an odd finding.
Here is another story (below) fresh off the news front from today once again on our friend the energy drink. Be sure to check out my last post on this topicfor more details and background.
As a side note, caffeine as you all know has been around for a LONG time. Manufacturers of energy drinks love it since it gives consumers something they can feel and it is dirt cheap to add to the drinks also. The safety record of it is also quite good since the LD 50 (the lethal dose to kill 50% of a population) is actually quite high. This is a good thing as in a perfect world you want the effective dose to be as far from the LD50 as possible (to minimize side effects). I will save you the pharmacokinetics talk!
Again, like all things moderation is going to be the best approach. I view the use of caffeine for most people as living on borrowed time and you will need to pay it back at SOME point.
If you are college student and want to know if you should have a cup of Joe during that boring lecture (not my lectures or labs of course!) check this out
Caffeine experts call for warning labels for energy drinks
Johns Hopkins scientists who have spent decades researching the effects of caffeine report that a slew of caffeinated energy drinks now on the market should carry prominent labels that note caffeine doses and warn of potential health risks for consumers.
"The caffeine content of energy drinks varies over a 10-fold range, with some containing the equivalent of 14 cans of Coca-Cola, yet the caffeine amounts are often unlabeled and few include warnings about the potential health risks of caffeine intoxication," says Roland Griffiths, Ph.D., one of the authors of the article that appears in the journal Drug and Alcohol Dependence this month.
The market for these drinks stands at an estimated $5.4 billion in the United States and is expanding at a rate of 55 percent annually. Advertising campaigns, which principally target teens and young adults, promote the performance-enhancing and stimulant effects of energy drinks and appear to glorify drug use.
Without adequate, prominent labeling; consumers most likely won't realize whether they are getting a little or a lot of caffeine. "It's like drinking a serving of an alcoholic beverage and not knowing if its beer or scotch," says Griffiths.
Caffeine intoxication, a recognized clinical syndrome included in the Diagnostic and Statistical Manual of Mental Disorders and the World Health Organization's International Classification of Diseases, is marked by nervousness, anxiety, restlessness, insomnia, gastrointestinal upset, tremors, rapid heartbeats (tachycardia), psychomotor agitation (restlessness and pacing) and in rare cases, death.
Reports to U.S. poison control centers of caffeine abuse showed bad reactions to the energy drinks. In a 2007 survey of 496 college students, 51 percent reported consuming at least one energy drink during the last month. Of these energy drink users, 29 percent reported "weekly jolt and crash episodes," and 19 percent reported heart palpitations from drinking energy drinks. This same survey revealed that 27 percent of the students surveyed said they mixed energy drinks and alcohol at least once in the past month. "Alcohol adds another level of danger," says Griffiths, "because caffeine in high doses can give users a false sense of alertness that provides incentive to drive a car or in other ways put themselves in danger."
A regular 12-ounce cola drink has about 35 milligrams of caffeine, and a 6-ounce cup of brewed coffee has 80 to 150 milligrams of caffeine. Because many energy drinks are marketed as "dietary supplements," the limit that the Food and Drug Administration requires on the caffeine content of soft drinks (71 milligrams per 12-ounce can) does not apply. The caffeine content of energy drinks varies from 50 to more than 500 milligrams.
"It's notable that over-the-counter caffeine-containing products require warning labels, yet energy drinks do not," says Chad Reissig, Ph.D., one of the study's authors.
Griffiths notes that most of the drinks advertise their products as performance enhancers and stimulants– a marketing strategy that may put young people at risk for abusing even stronger stimulants such as the prescription drugs amphetamine and methylphenidate (Ritalin). A 2008 study of 1,253 college students found that energy drink consumption significantly predicted subsequent non-medical prescription stimulant use, raising the concern that energy drinks might serve as "gateway" products to more serious drugs of abuse. Potentially feeding that "transition" market, Griffiths says, are other energy drinks with alluring names such as the powdered energy drink additive "Blow" (which is sold in "vials" and resembles cocaine powder) and the "Cocaine" energy drink. Both of these products use the language of the illegal drug trade.
Department of Sport and Exercise Sciences, Chelsea School Research Centre, Welkin Research Laboratories, University of Brighton, Eastbourne, BN20 7SP, UK.
A single protein meal increases recovery of muscle function following an acute eccentric exercise bout. Etheridge T, Philp A, Watt PW. Department of Sport and Exercise Sciences, Chelsea School Research Centre, Welkin Research Laboratories, University of Brighton, Eastbourne, BN20 7SP, UK. The purpose of this study was to examine the effects of acute protein ingestion on the recovery of muscle function and markers of muscle damage in the 72 h post eccentric-exercise. Nine recreationally active males recorded quadriceps maximum isometric voluntary contraction (MVC), peak 5 s power output (PPO), and perceived muscle soreness. Plasma creatine kinase (CK) and protein carbonyl (PC) content were measured prior to exercise. Delayed-onset muscle soreness (DOMS) was induced by a 30 min downhill run (-10 degrees ) at a target intensity of 75% age-predicted heart rate maximum, immediately followed by ingestion of 100 g protein (containing 40 g essential amino acids; PRO) or placebo (CON) solution. The pre-exercise measures were re-taken in the subsequent 24, 48, and 72 h. CK, PC, and perceived muscle soreness increased significantly following exercise and with each supplement at 24 h. PC and muscle soreness remained elevated at 48 and 72 h (p < style="font-weight: bold;">
Conclusion: Ingestion of a single post-exercise protein mixture increases the rate of force and power restoration at 48 h, suggesting potential for protein as an ergogenic aid during the DOMS period.
My Notes: Be sure to have some protein and carbs around your training time!
Chester N, Wojek N. Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom. n.chester@ljmu.ac.uk This study was undertaken to examine self-reported caffeine consumption and reasons for its use, amongst UK athletes, following its removal from the 2004 World Anti-Doping Agency (WADA) Prohibited List. A convenience sample of track and field athletes (n = 193) and cyclists (n = 287) completed a postal or Web-based questionnaire. Messages were posted on athletics and cycling club Web sites and mailing lists to direct athletes to the Web-based questionnaire. Postal questionnaires were distributed at domestic sporting events. A higher proportion of cyclists (59.9 %) compared with track and field athletes (32.6 %) consumed caffeine to enhance performance (p < p =" 0.031)" p =" 0.010)" style="font-weight: bold;"> Conclusion:Results revealed that amongst UK athletes, the intention to use caffeine as an ergogenic aid was high, and that use was more widespread and accepted in competitive sport, especially at elite level, when compared to recreational sport.
Jenkins NT, Trilk JL, Singhal A, O'Connor PJ, Cureton KJ. Department of Kinesiology, University of Georgia, Athens, GA 30602, USA. The purpose of this experiment was to learn whether low doses of caffeine have ergogenic, perceptual, and metabolic effects during cycling. To determine the effects of 1, 2, and 3 mg/kg caffeine on cycling performance, differentiated ratings of perceived exertion (D-RPE), quadriceps pain intensity, and metabolic responses to cycling exercise, 13 cyclists exercised on a stationary ergometer for 15 min at 80% VO, then, after 4 min of active recovery, completed a 15-min VO2peak performance ride 60 min after ingesting caffeine or placebo. Work done (kJ/kg) during the performance ride was used as a measure of performance. D-RPE, pain ratings, and expired-gas data were obtained every 3 min, and blood lactate concentrations were obtained at 15 and 30 min. Compared with placebo, caffeine doses of 2 and 3 mg/kg increased performance by 4% (95% CI: 1.0-6.8%, p = .02) and 3% (95% CI: -0.4% to 6.8%, p = .077), respectively. These effects were ergogenic, on average, but varied considerably in magnitude among individual cyclists. There were no effects of caffeine on D-RPE or pain throughout the cycling task. Selected metabolic variables were affected by caffeine, consistent with its known actions.
Conclusion: The authors conclude that caffeine preparations of 2 and 3 mg/kg enhanced performance, but future work should aim to explain the considerable interindividual variability of the drug's ergogenic properties.
Huang CC, Tsai SC, Lin WT. Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan, ROC. In this study, we report protective effects of dietary l-arginine (l-Arg) supplementation against oxidative stress and inflammation in aging rats during exhaustive exercise. Thirty 18-month-old male Sprague-Dawley rats were randomly divided into four groups: sedentary control (SC); sedentary control with l-Arg treatment (SC+Arg); exhaustive exercise (E); and exhaustive exercise with l-Arg treatment (E+Arg). Rats in groups SC+Arg and E+Arg received a 2% l-Arg diet. Rats in groups E and E+Arg performed an exhaustive running test on a treadmill. The mean duration of exercise differed significantly between groups E and E+Arg (51+/-6 versus 63+/-3min). Results showed significant increases in xanthine oxidase (XO) and myeloperoxidase (MPO) activities and in lipid peroxidation end-product (malondialdehyde, MDA) levels of myocardial, muscular, hepatic, pulmonary, and renal tissues of exercised rats compared with SC and SC+Arg rats. The increased XO and MPO activities and MDA levels significantly decreased in exercised rats that were fed a diet supplemented with l-Arg. We also found that l-Arg supplementation prevented exhaustive exercise-induced elevations of plasma aminotransferase activity, and lactate and uric acid levels in aging rats.
Conclusion: These findings suggest that l-Arg supplementation enhances exercise capacity and protects against oxidative damage and inflammatory responses caused by exhaustive exercise in aging rats.
My Notes: Keep in mind that this in our fury friends and human data on this is limited (translation--save your money for now on L Arginine)
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