HIITCore Fitness | Our Team | Alyssa Mazzella

Alyssa Mazzella - Co-owner/Fitness Director

  • Bachelor of Science Exercise Science
  • ACSM Certified Personal Trainer
  • TRX® Certified
  • Powerwave® Certified

Alyssa graduated from the University of New Hampshire with her Bachelor of Science in Exercise Science with a focus in Kinesiology; minoring in Nutrition. While attending UNH she conducted research of elderly individuals looking at the effects of exercise on building muscle under high loads, low loads, and low loads with a blood flow restriction. She also worked in the cardiac rehab facility. During her senior year of college, she interned for 400+ hours at Tufts Medical Center in the Cardiac Wing.

She has her American College of Sports Medicine (ACSM) Certified Personal Trainer and has been personal training for 10+ years. She is also TRX® and Powerwave® certified. Alyssa excels at strength and functional training, core conditioning, and cardiovascular fitness. Her clients often comment on her positive and enthusiastic attitude and credit her with motivating them to reach their full fitness potential. When not at work, Alyssa likes to stay active – she has been going backpacking for over 20 years. She also has played soccer, ran track, and recently started running half marathons to push her limits even more! Alyssa enjoys cooking and playing with her Border Collie rescue puppy, Scout!

Her goal is to promote fitness and well-being by optimizing the physical health of others by educating, motivating, and supporting them in exercise science-based fitness routines and healthy lifestyles.



"Most people join a gym on January first because their New Year's resolution is to lose weight and get in shape. This year, it took me an extra month to commit and so, on February 8, 2018, I met with Alyssa for the first time. I had never worked out with a personal trainer before, but since my attempts at weight loss had been a series of yo yo dieting, I thought a trainer would be the key to my future success and hold me accountable to stick with a lifelong fitness plan.”

"I'm pleased to say that Alyssa provided the motivation I desperately needed. She is extremely caring, enthusiastic, knowledgeable and most of all, supportive. I trained with her twice a week and did a combination of strength training and cardiovascular exercises. Throughout our training together, I felt that we were building a relationship and I never questioned that she had my best interest in mind.”

"Each workout was personalized and challenging to say the least. She pushed me and kicked my butt...but in a loving way! Whenever I felt I couldn't do more, Alyssa was right by my side encouraging me to continue...and I always did.”

"I have lost 30 pounds since I started training and hope to continue to lose more. Alyssa was quick to emphasize that it's not all about the scale but more importantly, how you look and how you feel. She is right. I have never felt in better shape, I have an increase in energy and I feel strong for the first time in my life. I look forward to turning 63 this August and continuing to be fit.”

By Marcia Gonzalez


"I met Alyssa a little over 2 years ago at a point in my life where I was extremely weak and very anxious about getting back into exercise. I had recently been the recipient of two organ transplants, a kidney as well as a pancreas, dialysis and my 21 years of being a brittle diabetic was over, but the ramifications of the horrible disease created chaos within my body and left me with major heart failure, cardio myopathy. So needless to say, I was terrified to hit the gym. However, from the moment I met Alyssa, I knew she was a person that could help me achieve my goals and also the one that would help change my life forever.”

"I started training with Alyssa and we worked slowly and cautiously. I wore a heart monitor and we continuously watched and tracked my heart rate, she slowly pushed me harder testing my limits and every time I told her I couldn’t do something she proved me wrong. In the beginning I could barely walk up stairs without getting winded and having to stop. But this only lit a fire within Alyssa to get me stronger and that passion in her made me want to come back day after day. I have been challenged and pushed by Alyssa, and she has taught me a great deal not just about exercise but about myself. She makes working out fun and inspires me to reach new goals unheard of when I first started training with her, our constant work together and her motivation pushed me to try new things.”

"I joined Alyssa’s’ HIIT60 class and soon after Crossfit. It’s because of her that I continue to train sometimes up to 6-7 times a week, because of her I attempted my first Crossfit Open, I ran my first mile since I was in High School, I’m deadlifting 315 pounds, bench pressing 200, the list goes on. Remember when I first started I could barely walk up stairs. From day one I have been completely impressed by her passion to help her clients, her knowledge, and her ability to connect with her clients and all individuals that happen to cross paths with Alyssa in the gym and I’m now the healthiest I can say I have ever been, even before I got sick. I’m now 30 pounds lighter and every day showing more definition and strength muscle wise.”

"When I first was diagnosed with heart failure I asked the cardiologist if this diagnosis would ever change, I was 30 years old and had a heart of an 80 year old. As of June 2018, at my recent appointment my doctor looked at me in awe and said, “you are a marvel of modern medicine and pure determination”, he called me a superhero I had made the impossible possible. I had reversed my heart failure. My constant training, cardio and lifestyle changes gave me back my strong heart. None of this would be possible if I did not have Alyssa, if she didn’t go above and beyond to listen, to learn and to help me overcome my fears. If I’m a superhero, she is definitely my partner in crime!”

By Steven Figueiredo