GSSI Webinar Q&A: An Update on Caffeine and Exercise Performance

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GSSI Webinar Q&A: An Update on Caffeine and Exercise Performance

Lawrence L. Spriet, Ph.D., FACSM |  April 23, 2024

Miss the webinar? Access it below.

Webinar Recording

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Q: Do you know caffeine’s impact on the fascia I’ve seen some things saying caffeine has negative effects of fascia system?

To be honest, I have not seen any peer-reviewed scientific papers on the effects of caffeine ingestion on fascia.

Q: There has been a lot of talk over the years in the fitness industry that caffeine is not good for your body especially when it comes to those with risk factors such as hypertension or other types of cardiac disease. Is caffeine really that healthy in general?

The reviews in this area suggest that moderate levels of caffeine intake (up to ~400 mg/day) does have some benefits for the cardiovascular system in terms of reducing the incidence of adverse effects and therefore longevity. At the very least it certainly does no harm.

Q: Is it ok to drink before scuba diving?

I believe it is if you regularly consume caffeine. I wouldn’t do it if not a caffeine consumer as it might increase heart rate and make a person more anxious which is not good when diving. If you did try it, use a low dose - 100 mg or less in the beginning.

Q: Is there consistent evidence for a detrimental effect of caffeine on performance beyond a certain dose? There appeared to be an attenuation of the performance benefit of caffeine in the study comparing 3, 6, and 9 mg/kg in the 9 mg condition. But I don't want to misinterpret those results.

You are correct – many people still improve with 9 mg/kg bm, but the side effects are more prevalent and possibly troublesome. The point is that taking more than 3 – 6 mg/kg bm in most cases provides no greater performance effects.

Q: Talk about the effect of caffeine on regular consumers vs. occasional or non-consumers of caffeine.

Caffeine consumption seems to improve performance in both groups, which I suppose is a little surprising for the habitual consumer of caffeine. One difference is that caffeine naïve people do experience more side effects with doses of 3-6 mg/kg bm, but the performance effect is still there.

Q: These studies and corresponding results are very interesting and exciting information to pass onto my clients.  Thank you for this helpful presentation and webinar!!

You are welcome.

Q: What about effect of cutting caffeine a week before a competition and then loading up the day of the competition?

Q: Is there evidence that tapering off caffeine use can help make caffeine more effective?

(Together) Studies have done this with 2, 4, and 6 days of withdrawal. Performance improvements do not seem to be any greater when doing this vs. just continuing with your normal intake. What does happen with withdrawal is that the subjects really do not like doing it and remark that it makes the withdrawal days very uncomfortable, so I never recommend this for people as they prepare for exercise and competitions.

Q: What is the basis for the 200 mg as an optimal dose? For example, is dose a significant moderator in meta-analyses and post-hoc tests show that 200 mg is better than other doses?

Q: You mentioned an absolute dose of 200mg may be optimal for most people. In your opinion, what would you consider the lowest effective absolute dose for exercise performance?

 Q: Is there a maximum recommended amount of caffeine that the average adult can consume for ergogenic results? At one point is it too much?

Q: The current consensus is ~200 mg for a performance benefit, but what about below that? Has that been well examined?

(These related questions together) The basis is many studies that show that ~ 3 mg/kg bm (or ~200 mg for a 70 kg person) provides performance improvements that are just as good as higher doses, and you have the added bonus of minimal side effects (such as sleep disturbance). Also, while I did not discuss it in the webinar, studies by Dr. Harris Leiberman have shown this to be at or near the optimal dose for maintaining alertness, focus, etc. at rest. Lower doses have also been shown to be ergogenic in some cases, but 200 mg may be optimal.

Q: In a marathon, when should the 2nd dose be taken?

If you normally drink coffee in the AM, you should continue to do so before a marathon. The timing of caffeine intake during the race is quite individual - I wouldn't take any early on – and concentrate on 2 doses in the second half of the race - maybe the first one between 20-25 km and second around ~35 km. Caffeine seems to be more potent the more tired you get, so will be very effective in the last 10-25 km. However, if you take when before the race or early on then use 3 doses.

Q: Side effects during exercise? Does timing or added/ food drink cause GI issues or any other side effects?

If you keep the doses at the low end, it does not seem to add to or cause any GI problems when exercising. It is induvial in terms of response, so needs to be trialed before any competitions.  

Q: What are your thoughts on the effects of caffeine pulling calcium from bones?

I have not seen any peer-reviewed work that suggests that this occurs.

Q: Could you give more information about RyR1, caffeine receptor on skeletal muscle?

The effects that caffeine has on this receptor comes from studies (in vitro) in the lab on animal subjects. The concentrations in these studies used to affect the receptor and keep the ability of muscle to contract are very high and non-physiological. Typically, they use 3-5 molar concentrations when they bathe the muscle whereas blood concentrations in the real world (in vivo) when you take 3-5 mg/kg/bm will be only ~15-40 micromolar, so the results are not transferable to exercising humans.

Q: With changes in CNS sensation, does it increase risk of injury?

That is a good question. If the caffeine reduces the feedback you get from the working muscles for instance, you can push a little harder, exercise a bit longer, etc. However, I am not aware of any evidence to support this possibility. An interesting aside is that caffeine is less effective when exercising in the heat – which might be good as the feedback from the temperature receptors in the body seem to have a more potent effect than caffeine (and opposite) on the brain – wants us to stop exercising or reduce the workload and keep the increase in core body temperature under control.

Q: What do you advise regarding allowing habitual caffeine drinkers to consume their normal amount of caffeine before an RMR test vs abstaining from caffeine before an RMR test?

I would argue that you shouldn’t abstain from your normal caffeine intake before the RMR measurement if you want a realistic finding. If this is what you normally do every day, then we want to know what your RMR is day-to-day. But convention wants us to remove this. It is strange but I am not aware of any study that has simply compared the two conditions (with and without) in a group of habitual caffeine consumers.

Q: A typical cup of coffee has how many mgs of caffeine?

Q: How many mg are there in a cup of coffee?

(Together) That is between 100-400 mg of caffeine depending on how it is brewed, etc. There are some studies comparing various commercial coffees, and home-brewed coffees considering size, etc. However, they show that even getting the same coffee from several Starbucks for instance can result in a lot of variabilty.

Q: I understand that caffeine consumption is highly individual but what would you say the ideal timing and type of caffeine would be? Like would energy drinks be a bad idea for endurance runners?

Q: Would we see differences in terms of side effects if research looked at pre-work and energy drinks as the source of caffeine? Not sure how many athletes (esp younger) are taking caffeine pills to get caffeine.

(These two together) For most activities, taking in a small dose of caffeine (2-4 mg/kg bm maybe) 30-60 min before exercise is reasonable for timing. What drink or capsule, gel, gum, or other source is highly individual. Normally, we recommend that the source of the caffeine be free from large amounts of carbohydrate or other compounds that may affect running comfort/performance. You can take caffeine in a sports drink (3-6% carbohydrate) but the energy drinks have higher amounts of carbohydrate at 10-12%. This high amount of carbohydrate is not recommended for endurance running (that’s why sports drinks have lower amounts), but taking one normally sized energy drink (~80 mg caffeine/250 mL) is fine an hour before exercise.

Q: Is caffeine in large doses considered a doping substance?

No, it is not. There are no restrictions from most organizations, including the IOC. The NCAA still has an upper limit that is allowed, but you would have to ingest ~8-10 mg/kg BM to get there.

Q: Does caffeine have a diuretic effect during exercise?

No, it does not. Several studies have confirmed this.

Q: When did the IOC okay the use of Caffeine?

It was always allowed up to a certain limit of caffeine in the urine. They removed this restriction in 2004.

Q: What are the concerns about caffeine withdrawal or crashing?

Q: Does the ergogenic effect of caffeine also decrease with developing tolerance to this addictive drug?

Q: Do individuals develop a resistance to caffeine?

(Together) By definition, caffeine is not addictive, but there is a dependence on caffeine. So, when you withdraw many people get a headache, feel tired, etc. Crashing is when you overdo the intake, and it seems to leave people with the opposite effects of smaller or regular doses – very tired and listless. While you do develop a tolerance to this drug in many ways, performance improvements are still present in habitual caffeine consumers.

Q: What should you do if you workout at night and want to take caffeine. Will it affect sleep quality?

It is individual, but I would recommend small doses for nighttime workouts. If it adversely affects sleep, then don’t use it.

Q: Any studies in adolescents?

Q: How about the impact on children and teenagers?

Q: Are there any possibilities for caffeine to be utilized by young athletes?

 Q: Have there been any studies done on teenage athletes to see if the ergogenic effects are the same or similar as an adult?

(Together) There are studies with “older adolescents” – 16–17-year-olds and the results are the same as for adults. Hard to get ethical clearance for studies with younger people and most people would recommend not taking caffeine in children and concentrate on training, nutrition, and rest. Many adolescents do take caffeine as they approach the age of 18.

Q: any differences in caffeine effects during different phases of the menstrual cycle?

That is a good question and to my knowledge has not been thoroughly studied. However, given the small if any differences in physiological responses between the menstrual phases, I would predict the differences would be minor.

Q: You mentioned that caffeine has an ergogenic effect on resistance training. Does this include all modes of performance, including power, amount of weight lifted, and endurance?

It appears that caffeine does positively affect all combinations of the above, given the different types of performance tests that have been studied.

Q: Is it just caffeine, or do its breakdown products play a role?

People have examined the breakdown products of caffeine, but they do not seem powerful, and their concentrations are very low compared to the caffeine levels.

Q: What are your thoughts on athletes or patients with anxiety taking caffeine as a preworkout?

For anyone that is anxious before a workout/competition I would not take any caffeine products beforehand. They might be able to take some later if the workout is long or repeated efforts are needed during the day.

Q: For slow metabolizers, would providing caffeine farther in advance of exercise be helpful? Or, is the problem that caffeine needs to get converted to paraxanthine, which may be providing the effect?

No, it won’t help to take it earlier. It is not the paraxanthine that has the effect. Trying a slightly higher dose might be worth a try – but it won’t work for everyone. Lots of evidence that caffeine is still effective in the so-called “slow-metabolizer” group.

Q: Why is caffeine on the WADA monitoring list and not the prohibited list given its ergogenic effects?

Ergogenicity is only one of the things that the IOC considers – they also monitor whether it will do harm, which it doesn’t and in reality, it is a part of the fabric for most countries in the world and cannot be realistically controlled. They state it is on the monitoring list, but they will never restrict it again. Compared to far more serious things that people take with real consequences to health, like steroids, etc., caffeine is not a concern.

Q: What was the amount of caffeine mg per kg that is safe. Does body weight or tolerance have anything to do with the amount?

At the lower doses body weight does not seem to be a large factor – hence the thought that ~200 mg might be good for everyone. I would recommend never going higher than 5-6 BM as there is no additional performance effect and side effects ramp up as you go higher. Tolerance is very individual and that is why an individual approach is needed - for some people 200 mg may be too much and some people can’t handle any.

Q: Have researchers seen that one type of caffeine source is better for performance than another? For example, is an energy drink more effective than other forms.

No, most sources of caffeine are effective. Some forms like gum and lozenges allow the caffeine to be absorbed a little quicker but after about 30 min it is in the blood from all sources. It will be interesting to see if aerosols are effective at getting caffeine into the blood quicker.

Q: I am an Athletic Trainer. My athletes ask me about the use of pre-workout all the time. What would your recommendation be to these athletes, should they substitute pre-workout with a different/lower dose method of supplementing caffeine?

Caffeine is an effective pre-workout supplement when taken 30-60 min before a workout – and the dose does not have to be high – trialing is needed – start with 100 or 200 mg. The dose would depend on many factors, the most important of which might be how long the workout lasts – a second dose could be taken halfway through or closer to the last section of the workout to help allay the fatigue that has built up.

Q: Is it safe enough to take caffeine without prior proper meal? Will there be any significant effect or difference on the individual during their performance?

Yes, it is safe to take with a meal or without a meal. While the meal may change the absorption and metabolism a little, enough caffeine still gets in to be effective.

Q: Is there a tolerance that develops with regular caffeine in regards to performance? If so, why, and how could you consider this for supplementation protocols?

There is tolerance but withdrawing from caffeine does not make it more effective. It is best to continue taking caffeine as you would from day-to-day and then add a dose before exercise, as this still produces a performance effect.

Q: Is there any evidence for an accelerated rate of caffeine metabolism when consumed during versus prior to exercise?

This has not been studied to any significant degree as it probably has little effect on the performance improvement that occurs. The studies that have been done over an hour of exercise or so, show that the caffeine concentration stays constant. Removal of caffeine through metabolism and excretion in the urine is slow.

Q: How does age affect the performance?

Q: It seems that the caffeine research focuses more so on athletes / healthy young adults.    Can you elaborate upon older active adults / seniors and their performance?

(Together) A good question and not that many studies with people as they get older – but it still seems effective in the older population. Its most powerful effect in older people may be to reduce fatigue and allow them to exercise longer.

Q: For combat sports, say Judo and Boxing, where the bout is 3 minutes long, how much time before will be an ideal time for caffeine intake for best results?

Again, taking the caffeine about 60 min before the first bout would be recommended. However, what to do if there were several bouts would be individual.

Q: Have there been any studies that explored the effects of caffeine among different ethnic groups?

I am not aware of any studies that have done this in the same study, but there are many studies from different countries and ethnic groups. I don’t believe there are major differences.

Q: Has there been any research on caffeine in individuals who tend to react differently? For example, if caffeine tends to make one sleepy, would performance be slowed or still enhance performance?

Yes, the response to caffeine is very individual. Typically, if a person experiences side effects that would impair performance, the dose has to be lowered or caffeine is not recommended for that person. We have only seen this when high doses (above 6 mg/jg BM) were given.

Q: Dr. Spriet, what are your personal experiences with caffeine usage? Would you recommend caffeine to individuals with any metabolic diseases/restrictions?

I don’t think that caffeine would be my first recommendation to people that have metabolic restrictions or diseases. Usually, in these cases exercising more, adapting to a healthier diet, and maximizing rest will have greater benefits that caffeine use.

Q: Roughly, how long would you say it takes for 3mg/kg of caffeine to completely exit the bloodstream? I've heard mixed opinions on this anywhere from 6-24 hours, and I know this would differ between individuals.

Yes, this is very individual, but it takes ~4-5 hours for half of the caffeine to be removed and then another 4-5 hours for the remaining caffeine to be removed, etc. So you could still have 25% of the original dose in the blood 8-10 hrs later and ~6% of the dose after 16-20 hours. In people with shorter or longer half lives for caffeine, the timelines would differ.

Q: Is it caffeine or the metabolites that are metabolically active? If metabolites, is it metabolized in the liver and, if so, why would we expect nasal sprays to work?

It is caffeine and not the metabolites that are active. The nasal spray is not about metabolism but getting the caffeine into the blood – possibly quicker than coffee or tablets. The liver will not know the source of the caffeine.

Q: For Glycogen depleted state, does it still work for those who are chronically eating (for on Keto) low carbohydrate?

That is interesting, as I have not seen a study that has examined the effect of caffeine for many months on a low-carbohydrate diet or even following them as they progress through this type of diet. I suspect, however, that caffeine would still be effective.

Q: Is there any validity or science to support the idea that delaying caffeine intake 90-120 minutes after waking improves alertness or reduces the risk of a caffeine crash?

No, I am not aware of any.

Q: Is it better to only consume caffeine prior to exercise? Or will you still see general benefits consuming at other times?

This depends on the length and type of workout/competition. If you need help early in the exercise or it does not last that long, then taking it before to get the caffeine levels in the blood up is recommended. In many situations people don’t need it at the start of exercise, so they may use it as the exercise is continued.

Q: When you said that caffeine use is independent of habitual caffeine use, does this mean that consumption of caffeine will be equally as effective in someone who uses the same amount every day, compared to someone who does not use it as often? in other words, does caffeine consumption cause a sort-of tolerance, making an athlete need more to perform well?

Q: Can you talk about caffeine tolerance?

(Together) Yes, you are correct. Caffeine does cause a tolerance for certain aspects, but not when it comes to performance. So, caffeine users should just continue what they consume and then dose before a workout/competition.

Q: Are similar effects seen with anaerobic exercise? Are there any ways that caffeine's ergogenic effect is different in more intense and short-term exercise bouts? Many of the studies discussed looked at aerobic exercise.

It does seem to improve activities where most of the energy for the task is from the anaerobic system – a short ballistic weight lift or a 30 s Wingate test. Not all studies show a performance effect as you might not expect or see an effect for a single weight lift repetition, but you might expect an effect over the course of a set or several sets.

Q: What should we or others look out for when utilizing caffeine in pre workouts or pumps? Are there ingredients that we should look for or stay away from?

I would suggest taking the caffeine in products where any other ingredients are not harmful - coffee, gum, tablets, etc. If you take caffeine in via energy drinks, sodas, etc. you’re also getting quite a bit of sugar.

Q: Any studies that look at other liquid sources of caffeine and exercise performance?  i.e. tea, pop...

Yes, there have been some – mainly coffee vs. tablets and decaf coffee. Tea and pop have not been used as much because the caffeine amount is very low. Plus, pop is carbonated and has sugar, which may not be desired. Some athletes will consume sodas late in a three-hour bike workout for instance but they flatten the drink beforehand and need the sugar.

Q: Do you have any thoughts on how low doses of caffeine may affect populations with neurological conditions such as Alzheimer’s and Parkinson’s? Asking from an exercise as medicine perspective and how boxing has been used as an intervention in the Parkinson’s populations in recent years.

There are generally positive effects of caffeine for Alzheimer’s disease, Parkinson’s disease, cirrhosis, fibrogenesis, some cancers, asthma, kidney stones and generally negative effects for: Huntington’s disease, arrythmia, tachycardia, and lung cancer.

Q: Does caffeine free up more fatty acids in the blood to be used as fuel?

Q: Does caffeine enhance lipolysis?

(Together) Caffeine has a very individual effect on stimulating free fatty acid (FFA) release from adipose tissue. We see some people increase the [FFA] from ~0.3 mM to 1 mM in the hour after caffeine ingestion and some that do not change. In the people where FFAs are increased they seem to be used as a fuel by the contracting muscles within the first 10-15 min of exercise.

Q: Question regarding cross over in breast milk, any studies on this?

Some caffeine does get into breast milk and it's recommended to limit your caffeine intake while breastfeeding, as the small amounts that gets into breast milk can build up in the baby over time. Still, up to 300 mg of caffeine/day is generally considered safe.

Q: Do you think that the evidence to date supports the need for CYP1A2 genotyping?

No, I don’t think you need to do this. If you try caffeine in training and competitions, you will find out of it is useful for your performance or not. If it is, you can experiment with different doses. The point is that even the so-called fast-metabolizers do not metabolize caffeine quickly, just a bit faster than the so-called slow-metabolizers.

Q: On the topic of Cognitive- any side effects from a cognitive standpoint?

Yes, if you take too much caffeine it can impair aspects of cognition. But the good thing is that you don’t need large doses to see some benefits on aspects of cognition – use 200 mg or less.

Q: Do you have any thoughts on caffeine’s affect for exercisers in fasted states?

Many studies have been done on performance following an overnight fast and it is still ergogenic.

Q: Have there been any studies in the elderly population where caffeine can help dementia patients?

There are some but I have never worked in this area. It seems that some studies have shown that caffeine in coffee and tea may reduce dementia risk by a small amount, while other studies show no effect or a slightly increased risk. 

Q: Caffeine and spinal cord injuries and possible side effect while training. Also does caffeine effect sensation?

This is an understudied area. Caffeine sensation would be disrupted depending on where the spinal cord injury is. It appears that many para-athletes do use caffeine, but the reviews in the are argue that the benefits of caffeine are not as clear cut compared to non-injured people. Lack of enough studies and the variation between injured people need to be examined. See Shaw et al. Nutrients 13, 2021 for a review.

Q: Is there any data regarding the benefits of caffeine isolated, versus caffeine plus other chemicals in its natural sources:  other xanthines, flavaloids, etc.

This has not been examined in great detail as the constituents that are in coffee besides caffeine are not considered to affect performance (more an affect on health) – so the study I showed where coffee was compared to caffeine tablets showed similar performance effects.

Q: Is the 200 mg per day or per serving - example, a dose in the morning and a dose in the evening?

No, this is more the potential optimal does to take before a workout/competition regardless of the time of day. 

Q: Has there been any findings on the long-term physiologic effects of habitual caffeine usage?

These studies examine the effects of habitual caffeine intake on several aspects of physiology/health and the results suggest that caffeine intake of up to 400 mg/day results in some benefits in some areas and no effect in others. These epidemiological studies are done to ultimately identify any negative health effects over years and a lifespan and caffeine use does not seem to be negative.

Q: Can you speak specifically to effects on GI peristalsis? Many suggest increased motility.

Caffeine binds to adenosine receptors in the GI tract and generally has a stimulating effect to increase motility. Again, however, this very individual. Using caffeine will identify what it does to you.