Should your clients use energy drinks to improve their exercise performance? The short answer is no. But it’s important to understand why.

Energy drinks, or “EDs,” are fundamentally different from sports drinks (e.g., Gatorade) and traditional beverages like coffee, tea, soft drinks, juices and flavored water. Most contain three major components: high levels of caffeine, sugar and an herbal “energy blend” consisting of taurine, glucuronolactone, guarana, gingko, B vitamins and L-carnitine.

Critically, many people consume multiple ED in one session—and some individuals are more sensitive to caffeine because of their genetics. EDs’ high caffeine content, combined with the fact that many of those who consume them are often caffeine naive—i.e., teenagers and young adults who don’t drink coffee every day—can lead to negative outcomes.

Because of the research my colleagues and I have performed, I don’t recommend people consume energy drinks in general, regardless of whether they’re exercising. EDs are associated with a number of complications, and with respect to the cardiovascular system specifically, ED consumption is associated with increased demand on the heart via increased sympathetic tone, blood pressure, inotropy and arrhythmias. Individuals may also experience reduced coronary artery blood supply via endothelial dysfunction, platelet aggregation, coronary thrombosis and coronary spasm. These factors can lead to acute issues for cardiac patients and healthy people alike.

Such effects are particularly prominent in certain vulnerable populations. Young people, those who are inexperienced with caffeine or particularly sensitive to it, smaller individuals, individuals with underlying cardiovascular or other conditions, pregnant or breastfeeding women, and people who consume multiple energy drinks in one session are all at higher risk for complications.

Children and adolescents appear to be especially vulnerable because they often fall into more than one of the above categories: caffeine naiveite, smaller body size and heavy or frequent ED consumption.

As with many topics, we need to do more research on the effects and safety of EDs in various populations. Though we are aware of many of the acute cardiovascular consequences of consuming EDs, we still have a lot to learn about their chronic cardiovascular consequences.

So, what’s the takeaway?

In general, people with a balanced diet that includes the appropriate macronutrients (proteins, carbohydrates, fats) for their levels of training and recovery shouldn’t need to use EDs to enhance their performance.

For short-duration exercise (< 1 hour), your clients should stick to drinking cool water only. If they are performing endurance exercise for more than an hour, especially if they are sweating a lot, sports drinks may improve their performance. Steer clear of EDs.

Related links:
ACSM statement | Energy Drinks: A Contemporary Issues Paper
Blog | Sports Supplements & Performance
Visual Abstract | Individualized Hydration Plans for Endurance Athletes

John P. Higgins, MD, MBA, MPHIL, is a professor of cardiology at McGovern Medical School at The University of Texas Health Science Center at Houston and Senior Cardiologist at Harris Health’s Lyndon B. Johnson Hospital. He is director of Exercise Physiology at Memorial Hermann Ironman Sports Medicine Institute and a sports cardiologist who works with the Houston Rockets and Rice University Athletics. He received his MD from the University of Queensland, Australia; a Master’s in Philosophy from the University of Cambridge; and an MBA from George Washington University. He completed a cardiology fellowship from Brigham and Women’s Hospital-Harvard. His research includes cardiovascular screening of athletes, energy drinks, smartphone apps and activity trackers, and teaching children first-aid. A strong advocate of “exercise as medication,” he is a marathon runner and has co-authored a children’s book on first-aid.

D-Glucosamine is an amino sugar synthesized from glucose and glutamine. It is found in cartilage, tendons and ligaments in our body. It is a component of glycoproteins, proteoglycans and glycosaminoglycans, which are the building blocks of cartilage. In human beings, glucosamine is synthesized endogenously from glucose but also may be obtained from exogenous dietary supplements. Glucosamine or its precursors, like collagen-containing food supplements, are commonly recommended to promote osteoarticular health. A typical use is to attenuate osteoarthritis in humans because of glucosamine’s high concentration in joint tissue. After oral administration, 87% of glucosamine is absorbed, and it is mainly incorporated into skeletal muscle and articular cartilage. Different studies have shown that oral glucosamine supplementation stimulates the synthesis of synovial fluid, inhibits degradation and improves healing of articular cartilage. However, despite extensive research, the data related to glucosamine’s effect on pain relief in patients with osteoarthritis have been inconsistent.

In the last few years, elite athletes have been taking glucosamine supplements because of their potential chondro-protective effects. But recently, some studies have shown that glucosamine has a favorable effect on cellular energy metabolism. The VITAL study evaluated the associations between a 10-year average intake of 20 dietary supplements (including 13 vitamins and minerals, fish oil, Gingko biloba, glucosamine, fiber and garlic) and mortality in a cohort of 77,719 subjects. For most of the supplements examined, there was no association with mortality. However, the strongest association with decreased risk of total mortality was that observed for glucosamine and chondroitin supplementation.

In our manuscript, published in the March 2022 issue of Medicine & Science in Sports & Exercise_®, we aimed to study the potential beneficial effects of glucosamine on mitochondrial content, physical performance and oxidative stress in mice that were aerobically trained and supplemented with three different doses of glucosamine for a period of six weeks. We measured exercise performance (grip strength, motor coordination and running capacity) before and after the training period. Proteins involved in mitochondrial biogenesis or content, like PGC-1, NRF-1 and cytochrome c, were increased by glucosamine supplementation in skeletal muscle. We did not observe changes in markers of oxidative stress (GSSG/GSH) or a damage like increase in lipid peroxidation (MDA) or protein carbonylation.

Our findings showed that glucosamine increases the protein levels of mitochondrial biogenesis markers and content. This resulted in an increase in motor coordination and also endurance capacity (i.e., the capacity to run long distances). This suggests that glucosamine could improve exercise performance, and it might be considered as an ergogenic aid — especially for cardio-respiratory training. Because glucosamine has an excellent safety profile and its adverse effects are uncommon and mild, it could be considered for use as a supplement for endurance athletes.

Jose Viña is a full professor of physiology at the University of Valencia in Valencia, Spain, where he combines his teaching duties with research work, the latter in two main lines: ageing and exercise. Viña leads a successful research group (FreshAge) working on different aspects of oxidative stress, with whom he has won numerous prizes for research work. He has published more than 300 papers on glutathione, mitochondria, exercise, ageing and nutrition.

Mari Carmen Gomez-Cabrera is also a full professor of physiology at the University of Valencia. She is the author of more than 120 peer-reviewed international publications, which have collectively accumulated over 8,500 citations in the broad area of exercise redox biology and more recently in healthy aging, frailty and sarcopenia.

Disclosure: Jose Viña is a member of the Scientific Advisory Board of NuSkin Pharmanex Research.

Viewpoints presented in SMB[JS2]  commentaries reflect opinions of the authors and do not necessarily represent ACSM positions or policies. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for SMB. 

Wellcoaches created the animated movie How Coaching Works to explain health and well-being coaching when the field was in its infancy. Now with almost 2 million views, the video remains a useful illustration of the best qualities of a helping relationship. Let’s take a look at the psychological underpinnings of the cartoon, which will provide insight into useful coaching-psychology principles and processes for the exercise professional.

Scene One: MEET

In this scene you find the coach in the office with a client. You may expect that it’s the coach’s job to tell the client what to do. Instead, the coach asks the client to create a picture of their vision, symbolized by the mountains off in the distance.

The client is eager to move toward that vision, and has even started doing some of the thinking necessary to get there, but feels overwhelmed by the things that stand between reality and the dream. The knotted path represents the many possible ways to reach the vision. It’s up to the client, with the coach’s support, to figure out which path is the best one.

The coach and client first agree on how they are going to work together. They shake hands, symbolizing the important boundary-setting conversation and agreement that starts a coaching relationship. For this relationship to promote growth, the coach radiates warmth, empathy, confidence, zest, humor and courage.

Scene Two: VISION

In the next scene, the coach encourages the client to get very clear about what it is that they want, and why. The coach gets the client motivated by encouraging them to explore why change is important now. The coach determines what it is exactly that the client wants to create—noting that all of life is invented and that together they will experiment with how to get from point A to point B.

Did you know that it’s all invented? According to the constructionist principle, we construct our reality—what we perceive, what we believe, what things mean and what we value. In other words, it’s all made up! And it’s from this frame of reference that the best coaches work with their clients. They playfully support the client in making up the rules to the client’s “game of life” and in experimenting with the ways to play it. The Art of Possibility, by authors Ben and Rosamund Zander, is a great source of inspiration for coaches. Check it out, and learn to say “How fascinating!” about all of life’s knots in the road.[JS1] 

Scene Three: THE PLAN

Notice that when the client works on their plan, the coach digs into the toolbox and hands over a tool—a big pencil. The client isn’t sure they can handle the pencil, but the coach’s certainty is greater than the client’s doubt. From the domain of hope psychology, we know clients have the willpower—now they just need to develop the “waypower.” And waypower isn’t best developed by being told what to do or having something done for you. It’s best developed by experimenting with the change yourself.

So the client gets specific about what they want to have happen—the specific changes that will take place in their life to get to the mountains in the vision. The more specific, the better. The box that the client draws represents the importance of focus and clarity when setting one’s goals. The client is exploring the question of what they’re going to take responsibility for creating—and doing—to reach the beckoning goal.

Scene Four: THE JOURNEY

As the coach presents the next tool, a trampoline, the client is beginning to feel more confident in their ability to take that first leap. The trampoline represents the power of setting goals that are appealing, specific and measurable—and of thinking through all that it will take to be successful, including the ever-important supporting relationships.

The coach invites the client to recall other times when they have achieved life or work goals, as well as their strengths and talents. It’s an opportunity to learn from past successes and to apply one’s strengths rather than focusing on what’s hard.

Now they construct more building blocks—the steppingstones to reaching success. The vision of the client’s best self becomes clearer and closer.

But as the client continues to experiment, they fall off of the ladder, missing a challenging step. This, of course, happens in real life—we lapse and fall back into our old habits. The coach brings a safety net, a nonjudgmental space in which they can explore what happened and what they learned from it. How fascinating! This leads to the client’s insight and decision to create smaller steps, drawn onto the ladder.

How important it is to move to action at the right time, with the right goal in mind? There is little benefit to clients of working on goals that are beyond their capability. When clients set goals that are well matched to their readiness to move forward, with enough stretch to be engaging but not too much to produce anxiety, they become aligned with their best self.

The client rises above the challenge, achieves the plan and jumps up, having grown into the image of their best self. They are excited as they experience what it feels like to be there—and that will propel more successes going forward.

Scene Five: SUCCESS

The coach and client end with a celebration—the client has found the best path, outgrown perceived roadblocks and become the vision of their best self. Together they heartily acknowledge the accomplishment.

The final scene is a cliff-hanger, so to speak. Its message of “To Be Continued” speaks to the fact that change is a journey, a process to revisit continually. We know that as the client continues down the road toward the vision, there will be another knot, or a ditch or a seemingly impenetrable object. Yet, through the coaching partnership that cultivates hope and the acknowledgement of strengths and abilities, the client will continue on the path and further develop their best self. 

Vitamin D plays an integral role in bone health through multiple direct and indirect mechanisms, including the regulation of calcium and phosphate metabolism. It is also well understood that severe vitamin D deficiency is associated with rickets in children and osteomalacia in adults. However, the relationship between vitamin D and bone is not straightforward. For example, vitamin D status and bone mineral density are not well correlated, especially in some populations, and poor vitamin D status is inconsistently associated with risk of stress and other fractures.

The seemingly complicated relationship between vitamin D status and bone health may be masked by the biochemical marker commonly used to assess vitamin D status. Assessment of vitamin D status via serum total 25-hydroxyvitamin D, or 25(OH)D, testing is common among the general population and many athletic communities. For example, more than two-thirds of NCAA Division I athletic programs reported routine vitamin D testing in 2019. However, bioavailable 25(OH)D concentration may be a better indicator of vitamin D status than total 25(OH)D concentration. Bioavailable 25(OH)D is most readily available for activation and interaction with tissues via vitamin D receptors and thus may better reflect true vitamin D status. In addition, bioavailable 25(OH)D has been shown to be associated with bone mineral density, particularly in Black and African American individuals (likely due to genetic variation).

In our study, published in the March 2022 issue of Medicine & Science in Sports & Exercise_® (MSSE), we explored the utility of bioavailable 25(OH)D in our cohort of male and female NCAA Division I athletes. Similar to previous findings, including those by Allison et al. also published in MSSE, we observed no association between serum 25(OH)D concentration and total body bone mineral density. However, we did observe a moderate association between bioavailable 25(OH)D and total bone mineral density (r = 0.618).

Of the 53 athletes in our study, 74% were classified as having low vitamin D status based on total 25(OH)D concentration (< 75 nmol/L). In contrast, only 19% were classified as having low vitamin D status based on bioavailable 25(OH)D (< 5 nmol/L). Importantly, more than half of participants (32% of white and 77% of Black or African American participants) would have been classified differently based on total and bioavailable 25(OH)D concentrations. In the clinical setting, using total 25(OH)D concentrations to determine vitamin D status, which is commonplace, may be sub-optimal. One risk is overtreating with vitamin D supplements, which at higher doses could result in hypercalcemia, weakness, bone pain, kidney stones and tissue calcification, among other adverse effects. Another risk is undertreating, which may have numerous impacts to health and performance.

Sports medicine clinicians and athletes routinely base vitamin D treatment and dosing decisions on total 25(OH)D concentration. However, without knowing bioavailable 25(OH)D concentration, a big part of the complicated story is incomplete. Further research into the use of the bioavailable 25(OH)D biomarker with athletes and into the development of a commercially available bioavailable 25(OH)D assay is needed.




Michelle Rockwell Ph.D., R.D., CSSD, is an assistant professor with the Department of Family & Community Medicine at the Virginia Tech Carilion School of Medicine and an adjunct faculty member with the Department of Human Nutrition, Foods, and Exercise at Virginia Tech. Dr. Rockwell’s vitamin D research has focused on the nutrient’s role in athletic performance, the utility of the total 25(OH)D biomarker, and clinical care patterns in a variety of settings, with a particular focus on overuse. She completed dietetics training at the National Institutes of Health, earned a Ph.D. from Virginia Tech, is a certified specialist in sports dietetics, and is a member of ACSM.



Enette Larson-Meyer, Ph.D., R.D., FACSM, is a professor at Virginia Tech in the Department of Human Nutrition, Foods, and Exercise, where she directs the Nutrition and Exercise Metabolism Laboratory. Her lab has been interested in the assessment of vitamin D status and its role in the health and performance of athletes since 2010. Dr Larson-Meyer is an ACSM fellow and serves as an associate editor for MSSE. She completed her dietetic training at Massachusetts General Hospital in Boston and her doctoral/postdoctoral studies at the University of Alabama at Birmingham.

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily represent ACSM positions or policies. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for SMB.