Our Staff

Julia Karlstad, M.Ed., NSCA-CSCS, ISSA-SFN

Founder & President, JKFITNESS, LLC

San Antonio Location

I’m Julia Karlstad and I am the President and Founder of JKFITNESS, LLC. I have worked in the fitness industry and specifically the medical wellness community for several years. I hold over fourteen years of experience developing, implementing and directing exercise, education and training programs within medical based programs and facilities. I am extremely passionate about helping people change their lives through fitness. My business, JKFITNESS, LLC, is a specialized personal training and wellness studio. We perform metabolic assessments, provide nutritional programs, outline individualized exercise prescriptions, and lead individualized and small group personal training sessions…all while focusing on a long-term lifestyle approach to complete wellness. I have a Master of Education in Exercise Science as well as a Bachelor of Science in Basic Sciences from the United States Air Force Academy (USAFA). I have authored two books about exercise as it relates to weight loss, “Rx Fitness for Weight Loss: The Medically Sound Solution to Get Fit and Save Your Life” and “Bariatric Fitness for Your New Life”. Additionally, I’ve been published in numerous periodicals and was featured with one of my clients on TLC’s “My 600 Pound Life” reality show. In 2013, I was voted Reader’s Choice “Best Personal Trainer” and in 2012 I was the “Featured Personal Trainer” on the cover of San Antonio Express’ Trends Magazine. I have a knack for motivating and excel in speaking platforms. I’ve been a guest speaker for several events and organizations to include: American College of Surgeons Annual Convention, Texas Association of Bariatric Surgeons Weight Loss Summit, Obesity Help Conference, Obesity Action Coalition’s Your Weight Matters National Annual Convention, Baptist Vascular Update Conference, the American Diabetes Expo, Methodist Health for Life Support Group, the Neurology Institute of San Antonio, the American Cancer Society and the Northern Arizona University Athletic Department. Before owning my own business, I personally developed and directed an exercise physiology program that consisted of two bariatric hospitals and three medically supervised weight loss clinics. I also spent ten years active duty in the United States Air Force and was an intercollegiate NCAA Division I athlete for the women’s basketball team at USAFA. I hold three nationally recognized fitness certifications and constantly pursue venues to further my formal education. I’m CPR/AED certified and I’m an active member of the American College of Sports Medicine, the National Strength and Conditioning Association, the American Diabetic Association and the Obesity Action Coalition.

Kimberly Black, E-RYT 200/RYT 500, YACEP, AFAA-CFT

Health & Fitness Professional

San Antonio Location

I’m Kimberly Black and my passion for health and fitness has spanned throughout my entire life. I have always led an active lifestyle; playing sports, as well as coaching and refereeing in high school. This passion led me to obtain my Bachelor of Science degree in Kinesiology with a specialization in Exercise Science from UTSA. While in college, I began to attend yoga classes and realized what an amazing affect it has on both physical and mental health. I have now been practicing yoga for over a decade. Upon completion of my bachelor’s degree, I decided I wanted to study yoga more in depth and I began my training to become a 200-hour registered yoga teacher. During my study I was able to link my passion for health and fitness with the yoga aspects of mind, body, and spirit.

My love for yoga has grown infinitely and is why I ultimately decided to continue my yoga training and am now a 500-hour yoga teacher and yoga continuing education provider.  I thoroughly enjoy spreading the message of self-acceptance, mindfulness, and self-awareness.

Bethany Reynolds, AFAA-CPT, FiTOUR-Advanced Barre, CI-GEL

Health & Fitness Professional

San Antonio Location

Hi, my name is Bethany Reynolds.  Teaching, training, coaching, and participating in the health and fitness industry has been my passion for 30 years. From taking dance classes as an adolescent, then exploring the world of aerobic exercise in a group setting, I was able to find joy in strengthening my heart and watching my body composition change for the better. I encourage you to let us help you find a passion for exercise and start or grow your path to health and wellness.

I hold a B.S. from Texas State University.  I started my career with a certification in Group Exercise Leadership through the Cooper Institute in Dallas, TX. I have since become certified in Personal Training (AFAA) and Advanced Barre (FiTOUR). I have continued my education studying female glutes, functional balance for aging adults, Pilates, TRX for senior adults, body mechanics, light dumbbell training, and Silver Sneakers.

Sarah Cotterman, NASM Certified Personal Trainer

Health & Fitness Professional

San Antonio Location

Himy name is Sarah CottermanIve always had a passion for fitness, from playing high school sports, to runningweight trainingyoga and outdoor adventures as an adult. I have a B.A. from Oakland University and am a NASM Certified Personal Trainer and a Girls Gone Strong Women’s Coaching Specialist. I enjoy empowering people to live their fullest lives through improving their health and fitness

Kelseia Hertzog, M.S., ACSM Certified Exercise Physiologist, RYT 200

Health & Fitness Professional

San Antonio Location

Hi, I’m Kelseia Hertzog. My love for the Health and Fitness industry started over 10 years ago. From my days as a cheerleader and weight lifting team member, I was able to explore different variations of exercise. This was the start of pursuing a Bachelor of Science in Kinesiology and later a Master of Science in Clinical Exercise Physiology. My time as a graduate student and Exercise Physiologist gifted me the opportunity to work with many special populations and through this gave me the confidence to train anyone with any condition.

I am an ACSM Certified Exercise Physiologist with an Exercise is Medicine level 2 credential. I hold a Basic Zumba certification and I am a 200-hour registered yoga instructor. I love being able to offer my clients different forms of exercise and educating them on the importance of having a balance between strength, cardiovascular endurance, and flexibility type workouts. I truly love what I do!

Carol Kline

Administrative Manager

San Antonio Location

Hi, I’m Carol Kline and I am the Administrative Manager.  I am passionate about helping people and living the principles of health, wellness, and nutrition.  I have been with JKFITNESS since 2015 and my I am the glue that keeps all the daily operations of JKFITNESS going strong.  My background is in administration and insurance where I spent nine years managing and selling health insurance along with co-owning and managing three Anytime Fitness franchises in Austin, Texas.  

JKFITNESS offers numerous services that are motivating, effective and safe despite the current COVID pandemic.Call NOW to change your life!
+