Sports performance is simple and definite. Someone wins, and someone else loses or comes second. Therefore, it is tempting to think in binary terms about other aspects of sports performance. The laws of physics predict that an increase in power-to-weight ratio will increase the speed of a body moving against gravity. If body fat (or other tissues not contributing to the power of movement) could be removed from our bodies as simply as removing Lego blocks, we should see an increase in running speed. Particularly for endurance athletes who move their body mass over long distances, often uphill. 

Successful distance athletes are lean. Observations that they cycle body mass and body fat levels over the season, with short periods spent at “race weight,” supports the “lighter is better” theory. However, sport also includes a sad side. For example, the “fat shaming” of Mary Cain and other promising athletes whose careers were cut short and made miserable by the pressure to be lighter and leaner. Relative energy deficiency in sport (REDS) describes a syndrome of health and performance impairments associated with problematic low energy availability (LEA) — chronic and severe exposure to undereating and/or overtraining that is often associated with weight loss attempts. 

Our study, published in the August 2023 issue of Medicine & Science in Sports & Exercise^®, was undertaken in recognition of the complexity of the issues. We attempted to investigate a real-world scenario — recruiting elite athletes (national-and international-level male and female race walkers) and involving real-life races (10,000 track races with judges and prize money). 

Previous laboratory and free-living studies of low energy availability have required participants to eat and exercise according to the same energy characteristics each day. Our approach, the Supernova camp protocol, manipulated tight dietary control around a real-life periodized training program where sessions change in volume, intensity and energy cost each day. After completing a test block, half of the race walkers completed 15 days of training (~19 km per day) with high energy availability (3,700 kcal per day) while the others commenced with six days of high energy before switching to nine days of severe energy restriction (~1,500 kcal per day reduction). All athletes reverted to a high-carbohydrate, high-energy preparation for post-intervention testing, just as they’d consumed for the first test block. 

This ~41% reduction in caloric intake created meaningful changes to body composition, with athletes losing ~2 kg of total body mass. Meanwhile, high daily intakes of protein were largely able to preserve muscle mass. Adherence to this diet resulted in increased perceptions of stress and fatigue, and a decrease in training quality. The walkers were ~4% faster in Race 2. However, a similar improvement was seen in the weight loss group as the group who consumed a high-energy diet for the duration of the study. In fact, when looking at all athletes in the study, there was no correlation between changes in body mass and changes in race performance. 

There are different ways to interpret these findings. The simplest view is that being lighter does not guarantee a better performance. The more nuanced is that performance in competitive endurance sport is multifactorial — and real-life athletes can’t remove body fat like Lego blocks without changing key influencers such as fuel levels, training quality and recovery, confidence/mood and potential loss of muscle mass. Our weight loss program was short and severe, achieving a 3% body mass loss. It caused acute impairment of energy levels and quality of life, but we were able to reverse this and restore race performance via 24 hours of refuelling. 

We emphasise that such severe energy restriction is not a chronic solution to body composition manipulation. However, if minor alterations are required, this protocol could be tweaked to include in the athlete’s annual plan either as a periodic activity or as a strategically placed activity to allow recovery before a race. Our final observation is that for an issue that is such a highly discussed and important topic in sports performance, there are pitifully few high-quality studies. 

Louise Burke, Ph.D., is a sports dietitian with 40 years of experience in the education and counselling of elite athletes. She was head of sports nutrition at the Australian Institute of Sport and the team dietitian for the Australian Olympic Teams (1996-2012). She is currently chair in sports nutrition in the Mary MacKillop Institute of Health Research at Australian Catholic University, has over 300 papers in peer-reviewed journals and is an editor of the International Journal of Sport Nutrition and Exercise Metabolism. Louise was a founding member of the Executive of Sports Dietitians Australia, is a director of the IOC Diploma in Sports Nutrition and an ACSM fellow. She was awarded a Medal of the Order of Australia in 2009 for her contribution to sports nutrition. 

Jamie Whitfield earned his Ph.D. in exercise physiology and muscle metabolism from the University of Guelph (Canada) and is now a research fellow in the Exercise and Nutrition Research Program at Australian Catholic University (Melbourne, Australia). His research utilizes a variety of research models to gain a better understanding of how nutrient availability alters skeletal muscle metabolism and whether it can promote or inhibit training adaptation and, ultimately, human performance capacity. 

Viewpoints presented in ACSM Bulletin commentaries reflect opinions of the authors and do not necessarily represent positions or policies of ACSM. 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 the ACSM Bulletin. 

1. Your college classes become way more interesting.

So much of the university experience can feel like it’s completely separate from the real world. But if you’re in exercise science or a related field, earning an ACSM Certified Personal Trainer^® (ACSM-CPT) certification will help you translate what you’re learning in the classroom into practical tools for your daily life.  

It could be as simple as practicing how to apply what you’ve learned in class to your own personal workout, or it could go much further — with an ACSM certification in hand, you can jumpstart your career by becoming a personal trainer, either at your university athletic facility or at a nearby gym, fitness studio or boutique. You'll be gaining valuable experience and earning money!

Here’s what Breaking Through Wellness owner Louise Valentine, who holds ACSM-EP, ACSM-CPT and ACSM-EIM II certifications and was ACSM’s 2023 Certified Professional of the Year, has to say:  

“After passing my ACSM-CPT exam, I made sure to get a training job right away. I couldn’t wait to go to my classes to learn something new to help my clients!” 

2. You’ll be more marketable after college — and able to earn more.

Most employers are looking at three specific factors when choosing the candidate they’re going to hire: education, certifications and work experience. By making sure you’ve got all three on your résumé, you can feel confident that you’ll stand out from the crowd. 

And if you’re getting certified, why not get the best personal training certification out there? The ACSM-CPT is at the top of the pile — Forbes named it the No. 1 personal training certification for 2023. 

3. You’ll be able to dial in your educational track.

By becoming a certified personal trainer, you’ll get hands-on experience with the types of work you could do after you graduate, meaning you can see whether you prefer teaching group exercise classes, one-on-one sessions, circuit training, etc. 

As a certified fitness instructor, you’ll get paid to experiment and learn about all these aspects of an exercise science and sports medicine career — all while still studying for your undergraduate degree. If you find you like or dislike certain styles of personal training, it’ll allow you to pivot in your studies and pursue the parts of the field that are more interesting to you. 

For instance, Valentine says, “[A] classmate shared while working as a CPT he quickly learned he loved training older adults and those coming back from injury. He used his undergrad CPT job to build a strong application to get into his PT school of choice and is now a successful Doctor of Physical Therapy.” 

4. You’ll learn soft skills — boosting your hireability.

Personal trainers spend a lot, if not most, of their time working directly with clients. Earning your CPT certification as an undergrad will give you the opportunity to hone your soft skills, giving you an edge against other job applicants once you graduate. If you can clearly and concisely explain exercises and complex movements to tired, (and occasionally unmotivated) people, you’ll be able to present yourself well and make your thoughts heard in any scenario. 

Kristin Traskie, ACSM-CPT, EIM, is the Fitness & Wellness Program Coordinator for Michigan State University’s Student Health & Wellness Health Promotion division and the inaugural winner of ACSM’s Certified Professional of the Year Award. To her mind, “Common soft skills for a personal trainer role include interpersonal communication, flexibility/adaptability, empathy, problem-solving, conflict resolution and motivational skills. Having these skills will position you for success in an evolving world.” 

5. Flexibility.

One of the best reasons to become a personal trainer is that certified fitness instructors often get to work flexible hours, perfect for students who need to fit their work schedules around classes and study time. If you’re looking for a source of income while you’re still in school, it’s hard to beat the routinely flexible hours of a personal trainer. 

Traskie recalls: “In college, I was able to train around my class schedule and extracurriculars. I trained at the campus recreation center and taught fitness classes at a local gym.” 

Bonus reason:

Improving your own health. A final benefit of becoming a certified PT? You get to take everything you learn about health, exercise and nutrition and apply it to your own life. Every time you teach your clients, look up new exercise programming, or brush up on your nutrition knowledge, you reinforce these same things for yourself. 

As Traskie says, “The advanced health, exercise and nutrition knowledge and skills you learn becoming and working as certified personal trainer will be valuable for your entire life. Not only will you be able to support others in achieving their health and fitness goals, but you can utilize the same knowledge and skills to achieve your goals.” 

Ready to take the next step? Learn how to become an ACSM Certified Personal Trainer^®. 

Related Content: 
Resource | ACSM Career Guide
Course | ACSM-CPT^® Prep Course & Exam Bundle
Blog | 5 Skills of High Performers in the Fitness Industry

Louise Valentine, MPH, ACSM-EP, ACSM-CPT, ACSM-EIM II, CSCS, CHES, BCTMB is the 2023 American College of Sports Medicine Certified Professional of the Year.  She owns Breaking Through Wellness, where she educates and empowers women ages 35 and beyond to maximize health, fitness and running despite changing hormones. 


Kristin A. Traskie, M.P.H., ACSM-CPT, EIM is the fitness and wellness coordinator in the Health Promotion Department at Michigan State University (MSU). Traskie’s mission is clear: Create a culture of health and well-being on campus and in the surrounding community. In addition to ACSM certifications, she also holds certifications from several other organizations. She uses research-backed knowledge from those fitness certifications to create holistic wellness and movement opportunities. Her work through MSU’s Health Promotion Department, Exercise is Medicine® on Campus initiative, Well-Being Coalition and The SPARTANfit Fitness and Wellness Program is improving health outcomes and life satisfaction for students.

A group exercise instructor is a fitness professional who safely teaches, leads and motivates individuals through intentionally designed exercise classes. Those who are ACSM Certified Group Exercise Instructors (ACSM-GEIs), provide safe and effective instruction across many class types, from dance fitness, to indoor cycling, to high-intensity interval training (HIIT) and everything in between. 

ACSM-GEIs come in all forms: some are full-time group exercise instructors, some teach group classes in addition to seeing personal training clients and/or offering health coaching, and others teach in addition to another line of full-time work to either supplement income or simply because they enjoy it! If you’ve been considering adding “Certified Group Exercise Instructor” to your resume, there’s never been a better time! 

Check out these 10 Tips for Success on the ACSM-GEI Exam: 

1. Understand the professional scope for an ACSM-GEI 

Professional scope (also called scope of practice) defines what an ACSM-GEI understands and can safely and effectively perform based on their certification, education, training and experience. For a full chart of “Can Do” and “Cannot Do” items, consult Table 1.4 in ACSM’s Resources for the Group Exercise Instructor, 2nd edition. 

2. Ensure you meet the qualifications

The minimal qualifications to sit for the ACSM-GEI exam are:

• 18 years of age or older
• High school diploma or equivalent
• Current adult CPR/AED certification

3. Develop a timeline 

Set a goal for when you would like to take the exam, and develop a timeline with clear priorities and expectations so that you can manage your time effectively. Every exam candidate differs in their academic background and practical experience, so it would be difficult to prescribe one timeline to meet the needs of each candidate. Use the other tips listed here to help you build your own timeline.  

4. Be familiar with the exam content outline 

ACSM provides an exam content outline for the GEI, which is made up of a job task analysis (JTA). This document serves as a blueprint for the certification examination. The outline is categorized into categories called performance domains (I, Class Design; II, Leadership; III, Instruction; IV, Professional Responsibilities). Within each domain is a list of tasks and statements that describe what an ACSM-GEI should know and/or be able to perform as part of their job. When preparing for your certification exam, it is important to use this document as a study guide because all exam questions are based on this outline. Download the document here! 

5. Create a study plan and find available resources 

There are many resources available to help you prepare for the ACSM-GEI certification exam, so it’s important to identify which resources will best fit your individual preparation needs. ACSM recommended options include: 

• ACSM’s Resources for the Group Exercise Instructor, 2nd edition 
• ACSM’s Guidelines for Exercise Testing and Prescription, 11th edition 
• PrepU: a quiz platform that adapts the questions asked based on your current proficiency
• ACSM Certified Group Exercise Instructor Study Group on Facebook (This is totally free!) 

6. Be knowledgeable about various group exercise formats 

It is beneficial to understand the various types of classes that an ACSM-GEI can lead, as well as the types of equipment that can be used in group exercise classes. Attending a variety of group exercise classes can prepare a future instructor by understanding the different class formats and seeing the many responsibilities of a GEI before, during and after they teach a group exercise class. Participate in group exercise classes when you can and, if possible, take a moment to talk with the instructor afterward. 

7. Find a mentor 

While you’re talking with those instructors, ask one to be your mentor. Look for a mentor who has experience in a variety of group exercise formats, is willing to spend time answering questions and encourages you as you begin your GEI career. A good mentor can teach you valuable skills such as how to structure a class and select appropriate exercises. 

8. Gain experience leading a group exercise class 

There is no better teacher than experience! Look for a facility that will allow you to teach or co-teach a class under another certified GEI's direction. This experience can be invaluable in becoming comfortable in front of a group and interacting with participants. This also is a good way to learn how to provide modifications, variations and progressions for your participants. 

9. Understand what you will need to keep your certification up-to-date 

The ACSM-GEI certification is valid for a three (3)-year period upon successful completion of the exam. You’ll need to pursue continuing education opportunities to maintain your certification and ensure that you are providing the best possible instruction to your students. To recertify, you’ll need to do the following: 

• Obtain 45 continuing education credits (CECs)—Learn more about CECs here. 
• Maintain a current CPR/AED certification
• Pay the required recertification fee (currently $55)  

10. Schedule your exam 

Once you’ve followed the above steps and feel confident that you’re ready, schedule your exam (you can do that here). You can take the exam in-person at a Pearson Vue testing center, or online from the comfort of your own home. You’re on your way to a new or expanded career as a certified group exercise instructor! 

*Bonus tip* Earn discounts on prep materials and the exam as an ACSM member 

ACSM members receive a 20% discount on resources from our publishing partner Wolters Kluwer, including the recommended books. ACSM members also receive a $100 discount on the cost of the exam! Once you’re certified, ACSM members also receive discounts (up to 50%) on online continuing education courses through ACSM’s ceOnline, and complimentary access to ACSM’s Health & Fitness Journal^®, an invaluable resource of education and practical tips for practicing exercise professionals. You can learn more about ACSM membership and join here.


This blog is adapted from "Ten Tips on How to Prepare for the ACSM Group Exercise Instructor^® Certification Exam," published in the July/August 2023 edition of ACSM's Health & Fitness Journal^®.