HomeNewsSpilling the Beans About Coffee, and Biomarkers and You

    Spilling the Beans About Coffee, and Biomarkers and You

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    The American College of Sports Medicine (ACSM) is the nation’s largest group of exercise physiologists, sports nutritionists, and a multitude of other sports-medicine professionals. Each year, at ACSM’s annual meeting, members gather to share their knowledge and latest research. Here are highlights of two presentations from the June 2022 meeting in San Diego that might be of interest to rowers intent on improving their performance. 

    Coffee, Caffeine and Caffeinated Foods: What Do Athletes Need to Know?

    Speakers: Louise Burke, Australian Catholic University, and Ben Desbrow, Griffith University, Australia 

    • Guidelines regarding the use of caffeine to enhance athletic performance have changed significantly. Caffeine was once believed to be a diuretic, beneficial in high doses primarily for marathoners, and most effective when consumed an hour pre-event. Almost every aspect of those ideas has been replaced with newer knowledge

    • Caffeine is not just for marathoners; it offers a three-percent improvement in performance in many sports, including races shorter than a marathon and in team sports. In addition, caffeine may help athletes such as bodybuilders train harder.

    • Caffeine offers similar benefits whether you take it one hour pre-exercise or only during exercise. Even low doses of caffeine (as in a gel or caffeinated gum) are effective when consumed just prior to the onset of fatigue.

    • Caffeine helps athletes train better when they are jetlagged or when their circadian rhythms are out of line. 

    • Caffeine comes in many forms, including caffeinated water, potato chips, gums, gels, sprays, pouches, strips, medications, pre-workout supplements, and pills. The caffeine content of commercial pre-workout supplements can vary from batch to batch (about 40 milligrams of difference per serving). Among the top 15 most popular pre-workout supplements, caffeine content ranged from about 90 to 390 milligrams per serving and often contained more or less of what was listed on the Nutrition Facts panel. 

    •  Rowers need to learn from their own personal experiences the right caffeine source and dose for their bodies. Genetics influences the enzymes that break down caffeine. 

    • If you consume one cup of coffee in the morning, most of the caffeine will have dissipated by lunchtime. In general, caffeine stays in the body for about seven hours. Its half-life (time taken for caffeine in the body to drop by half) might be five hours (or less) for some rowers but 10 hours (or more) for others. 

    • Female rowers should know that birth-control pills almost double the half-life of caffeine, making it more effective for longer exercise sessions.

    • If you happen to be a slow metabolizer and then take a pre-workout caffeine boost before your afternoon workout, you might have some caffeine “overlap” from your morning cup of brew. Even if you abstain from caffeine for 12 hours, circulating caffeine might still be detected in your blood because of caffeine accumulation with repeated caffeine consumption. Depending on your tolerance, this could be helpful or harmful.

    • Habitual caffeine intake does not seem to influence its energy-enhancing effect across a range of different sports. That means that if you regularly consume coffee every day, there’s no need for you to stop consuming it for a few days before competition. Caffeine withdrawal feels horrible, and you’re unlikely to gain any benefits. 

    Biomarkers That Impact Training and Performance

    Speaker: Shawn Arent, University of South Carolina

    While caffeine is a substance that can be consumed to enhance performance, biomarkers are substances in the body that are indicators of physiological processes. Endocrine biomarkers measure stress and adaptations to training.  Biochemical biomarkers measure muscle damage and inflammation. Nutritional biomarkers measure the impact of diet, such as on blood glucose and iron levels.  

    Biomarkers are best used to document changes over time (as opposed to taking one measurement, such as serum ferritin, to see if the measurement simply falls within normal limits). Biomarker data can help assess changes in performance, recovery, and training optimization. Biomarkers might be able to predict and prevent illness. In an eight-week basic training study, a third of the soldiers whose biomarkers classified them as being over-reached experienced illness. 

    • The military and some professional athletes and teams are very interested in measuring biomarkers. Connecting biomarkers to measurables like performance, training, sleep, and diet provides context and meaning for the measurements. The goal is to be a healthy athlete who can stay in the game and contribute to a winning season.

    • With biomarker research, we now know that food deprivation can be more detrimental to performance than sleep deprivation. With Army-ranger training, a 1,000-calorie-per-day deficit reduced testosterone and increased cortisol. Many markers can take a full month post-dietary restriction to get back to normal. 

    • Biomarkers can document the physiological impact of restrictive food intake and show how much better athletes such as rowers can recover when they are adequately fueled.

    • Both physical and psychological stress impact biomarkers, as does travel through time zones. Seeing sleep data can help rowers and other athletes learn the value of prioritizing sleep.

    Wave of the future?

    Rowers who are interested in getting their biomarkers measured should know this is an emerging field with yet unanswered questions, including: 

    What is the best time to measure biomarkers? (Should recovery markers be measured right after exercise or a day later?)  

    How often should measurements be taken? (Might depend on who is paying the bill!) 

    Should athletes not exercise the day before blood draws/data collection?

    Do biomarkers differ when measured under research conditions? (That is, does lab data compare to data collected at a real-life competitive event such as a regatta?) 

    What is the minimal performance-enhancing level of a biomarker? Is higher better?  When is a level too low?

    Can biomarkers predict and prevent illness? 

    And very importantly: Will coaches (and athletes) be willing to alter their training schedules based on biomarkers? The buy-in of coaches is essential, as is the willingness of athletes to alter training plans.

    With time and well-established protocols for measuring biomarkers, this evolving field will have a significant impact on improving the health and performance of members of the military, professional athletes, as well as rowers, and curious consumers who can afford this luxury.  

    Sports nutritionist Nancy Clark, M.S., R.D., C.S.S.D., has a private practice in the Boston area. She is the author of the best-selling Nancy Clark’s Sports Nutrition Guidebook (

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