CrossFit 646
75 W. River Rd suite 101
Tucson AZ 85704
Phone: 520-612-7056
CrossFit 646 North
8591 N. Silverbell Rd.
Tucson AZ 85743
Phone: 520-389-8837

Our Staff

CrossFit, Tucson, Staff, Coaches, Teachers

THE CREW, A.K.A. “The League of Extraordinary CrossFit Coaches”




  • Matt York - Owner

    Master of Science - Exercise, Fitness & Health Promotion
    Bachelor of Science - Exercise Science
    Associates – General Studies
    Certified CrossFit Trainer (level 3)
    CrossFit Level 2
    CrossFit Level 1
    CrossFit Kids
    NSCA – Certified Strength & Conditioning Specialist
    FAI – Certified Functional Aging Specialist
    USA Weightlifting Club Coach
    American Red Cross - CPR-AED

    Work Experience
    Current: Co-Owner CrossFit 646
    Current: Strength Coach Salpointe Catholic School
    Strength Coach St. Stephen's & St. Agnes School
    Strength Coach American University
    Strength Coach Temple Unviersity
    Strength Coach DC Divas

    Matt has a Bachelor of Science degree in Exercise Science and a Master’s Degree in Exercise, Fitness and Health Promotion from George Mason University.  While at George Mason, Matt also played for the Patriot’s Division 1 baseball team.  Matt also graduated with an associate’s degree from Cochise College while playing baseball for the Apaches.  Matt began his work in the field in 2006 working for Tony Decker at Temple University where he helped implement strength and conditioning programs for the Owls football, baseball, crew, basketball, track, tennis, and volleyball teams.  In 2007, Matt took the assistant strength and conditioning coach position at American University in Washington DC where he worked with all sports for the Division 1 Eagles athletics program.

    After leaving American, Matt became the head strength and conditioning coach at the prestigious St. Stephen’s & St. Agnes School in Alexandria VA, where he worked for 6 years.  At SSSAS, Matt was responsible for teaching and overseeing the Upper School’s physical education classes, coaching the Olympic Weightlifting Club, and training all of the school’s sports teams. While at SSSAS, Matt started a school non-profit CrossFit Affiliate called CrossFit SSSAS and re-wrote the Upper School’s Physical Education Curriculum to incorporate CrossFit methodology.  During this time, Matt trained kids and teens from age 10 to 18 and he prided himself on being able to motivate students of every ability level, from non-athletes to the future professional athlete.

    In 2009, Matt was also the strength and conditioning coach for the women’s professional football team, the D.C. Divas during which time the team finished 2nd out of 56 teams.  Matt also worked as a personal trainer and strength coach at Breakaway Fitness and Breakaway Sport in Tyson’s Corner Virginia with his wife Melissa.  While at Breakaway Fitness, Matt had the opportunity to work with people of all ages and training backgrounds.

    Matt has competed and coached in CrossFit, powerlifting and Olympic weightlifting.  In 2008, Matt held two records in the International Powerlifting Association for the Squat, and Total in the Raw Amatuer 181lbs weight class.  Matt also won the Olympic weightlifting Blue Ridge Championships and Virginia State Championships in 2011 in the 85kg weight class as well as the 2011 Capitol City Open in Washington DC.  Matt has also coached at the last 5 consecutive USA Weightlifting National Championships as well as many local meets in Arizona, Virginia, Washington DC, Pennsylvania, New Jersey and Maryland.

    Matt co-authored an article that has been published in the October 2014 edition of the International Journal of Athletic Therapy and Training, which was titled, “Neck Strengthening Recommendations for Concussion Risk Reduction in Youth Sport.”

    Most recently, Matt has taken an interest in improving function for the active aging population.  His goal with this program is to help active adults continue the activities they love throughout their later years in hopes to add life to their years and not just years to their life.  His influences are Dr. Cody Sipe and Dr. Dan Ritchie from the Functional Aging Institute, from which he has obtained their distinction of Certified Functional Aging Specialist.

    Since Matt has moved to Tucson he has been coaching Olympic weightlifters, training athletes, personal training people of all ages and ability levels, and is now fulfilling his dream of running a gym alongside his wife Melissa in a location they love!  Matt is truly passionate about training people who have a genuine desire to improve their performance and lifestyle and is grateful for the opportunity to play a positive role in every client’s life, no matter how large or small.


  • Melissa York - Owner

    Bachelor of Science – Exercise Science and Business
    NSCA – Certified Strength & Conditioning Specialist
    USA Weightlifting Club Coach
    CrossFit Level 2

    Melissa grew up in Michigan but has also lived in Missouri, Illinois and Virginia. She is a graduate of George Mason University (GMU) where she studied Exercise Science and Business. At GMU Melissa was a two-sport athlete in Volleyball and Track & Field.  During her four years at GMU she researched injury correlation to gender and sport, as well as how to reduce specific injury rates through proper training and instruction.

    She currently competes in CrossFit and Olympic Weightlifting, and has competed nationally in weightlifting since 2010, holding several records in the Maryland & Potomac Valley area and has finished as high as 5th at the USA Weightlifting National Championships.

    Previously, she was general manager at BREAKAWAY Fitness and Sport in Virginia. While working as the general manager she also trained all types of individuals and athletes – injury clients, elderly population, and athletes from an array of sports including high-school athletes, Olympic weightlifters, CrossFit athletes and athletes at the collegiate level (working with athletes from every sport at Georgetown University).

    After visiting her family in Tucson she quickly grew to love it and decided to take the leap across the country where she can enjoy the sun and wonderful people while she helps others change their lives through healthy choices, fitness, education and a new way to look at health care.

    She joined Rejuv Medical Southwest in March of 2014 to head up the Medical Fitness division of the company as Medical Fitness Director and Head Personal Trainer.

     In January of 2015, Melissa and Matt decided to follow their dreams and open a gym of their own. “I have always wanted to really help people, inspire them and encourage them to make changes in their life so they can enjoy all life has to offer them and so much more. This is a journey that will last a lifetime and I want to be there to help.” CrossFit 646 is where she found this opportunity. She is very excited to be a gym owner, which will allow her to be a key player in changing the lives of the people who entrust their health to her. .

    When Melissa is not working at CrossFit 646 to change lives, she is training hard as a competitive Olympic Weightlifter, spending time with her husband Matt, and their two dogs Georgia and Kasey. She also loves being outside, cooking, writing, hiking and taking pictures.

    “The secret of Change is to focus all of your energy, not on fighting the old, but on building the new.” – Socrates


  • Courtney Dyer

    Bachelor of Science in Nursing – Grand Canyon University
    CrossFit Level 1
    Registered Nurse

    Courtney was born and raised in Tucson Arizona. Before starting CrossFit, Courtney had never competed in sports. She worked out and did some yoga as well, but never worked too hard when it came to physical and nutritional endeavors. Her life changed forever when she found CrossFit. She began taking CrossFit classes at 646 and found that she picked up the movements very well, even though she couldn’t back squat the 45 pound bar in the beginning. She took a liking to the Olympic lifts and after some training, she did her first weightlifting competition in 2015 where she went 6 for 6. Since then, Courtney has won a few local competitions and even competed at the 2016 University National Championships! Even though her qualifying total was ranked 38th in the 63 kg weight class, Courtney exceeded expectations by finishing 7th at University Nationals and 5th for the Under 25 National Championships and her total of 165kg qualified her for the 2016 American Open! Courtney is looking forward to helping other people meet their fitness and health goals as she has done. Courtney truly is living proof that every person can meet their goals with consistency, determination and a little fun! In addition to coaching, and working out every day, Courtney is also a full time Nurse in Tucson.


  • Rachel Carramusa

    Bachelor of Science in Physiology - University of Arizona (in progress)
    CrossFit Level 1

    Rachel was born in northern California and moved to Arizona with her parents in 2001. Rachel began soccer at the age of 6 in California and played competitively when she moved to Tucson for Tucson Soccer Academy and Rush Soccer Academy until she graduated high school from Catalina Foothills. In her last years of competitive soccer, Rachel had to get shoulder surgery twice causing her to have to take time away from the sport she loved. After starting her undergraduate schooling at the University of Arizona, as a proud Wildcat, she soon found herself bored and extremely out of shape and none of the intramural activities on campus caught her eye. Then one of her friends brought her to 646 to try out a class. She fell in love with the friendly competitiveness that CrossFit entailed and jumped right into it. In the midst of her start at 646, Rachel realized it was time to focus on her health and nutrition and lost over 25 pounds in just a few months. She saw how CrossFit had changed her life physically as well as mentally and loved everything about it. Rachel began interning and coaching at CrossFit 646 because she wanted to help give others the opportunity to learn to love CrossFit and believe in the methods of community based functional fitness as well. Rachel is currently finishing up her last credits at the University of Arizona to receive a Bachelor’s of Science in Physiology.

  • Nicole (Nikki) Francesco

    Masters of Business Administration (University of Arizona)
    CrossFit Level 1

    Nikki was born and raised in Tucson, Arizona and attended Salpointe Catholic High School and the University of Arizona. Always active as a child, Nikki participated in many sports including volleyball, soccer, track/field, and softball. As an adult, she found a love for group exercise classes and actively participated in kickboxing, zumba, hip hop dance and boot camps. She eventually became an instructor and spent many years leading kickboxing classes, often with more than 30 participants per class. In 2015, Nikki came in to 646 for some personal training, looking to add more weight training to her exercise regimen. After two months of personal training, she participated in her very first CrossFit class; a moment Nikki references as “life changing”. Her enthusiasm for the Sport of Fitness, along with her instructing experience caught the eye of Matt and Mel, who suggested she pursue a CrossFit Trainer Certificate and instructing at 646. Nikki loves CrossFit because it’s allowed her to discover capabilities she never knew she had. She loves the friendly competition, the community, and most of all the excitement of finishing a really tough workout. She loves coaching because she enjoys sharing her experience as an athlete, and thrives on those moments when her participants find themselves experiencing their “firsts” and achieving their fitness goals. When she’s not in the gym, Nikki is a Healthcare IT Consultant and participates in team sports multiple times per week.

  • Josh Dyer (Intern)

    Bachelor of Science in Public Safety and Emergency Management. (Grand Canyon University)
    Certified Emergency Care Technician.
    Certified Healthcare Provider BLS
    Certified Personal Trainer

    Josh was born and raised in Tucson, Arizona. He was a competitive athlete in high school participating in football, wrestling, and track. In the football weight room is where he discovered his passion for weightlifting. Post high school graduation he began coaching as an assistant football coach specializing in the weightlifting program. This is where he discovered his love for teaching and encouraging others. In the years to come Josh hit a plateau in his weightlifting and was losing his passion for the sport. This opportune time was the beginning of his exciting and challenging relationship with CrossFit. Immediately he enjoyed the gymnastic and Olympic lifting aspects of CrossFit and only recently has learned to love the cardio aspect. He believes CrossFit is not only an effective and fun way to train but also an avenue for friendships that will last a lifetime. Josh’s decision to pursue coaching is a reflection of his enthusiasm for the sport, and for helping others achieve their goals.

  • Samantha Mowbray (intern)

    Sam is a Learning Specialist with Intuit. Her daily focus is on coaching and developing facilitators around the world to perfect their craft and deliver the best possible experience to those who support Intuit customers. Sam tried her first Crossfit class in late 2015, but didn’t commit daily until June 2016 while traveling for work and visiting various boxes around the US. A coach once quoted James Fitzgerald, “There are few places on earth where we are asked to make that very real connection with our body and our spirit. CrossFit is one of those places. Dig deep, don’t quit, and discover why you are here.” This message inspired and drove a focus inside her. Her passion for Crossfit comes from seeing people improve every day. It’s so exciting to see someone do something they couldn’t do yesterday. Combining a love of Crossfit and a love to see others grow… Sam is driven to fulfil a dream of coaching. Sam tries to remind anyone she speaks with to not compare yourself to others. Everyone has their own strengths and weaknesses. Spend time improving both and enjoy the journey.

  • Michael Smith (intern)

    Masters of Arts in Human Performance and Physical Education - Adams State College
    Bachelor’s of Science in Education - Chadron State College
    USATF Level 1 Track and Field Coach
    First Aid
    Arizona Certified Secondary Physical Education and Health Teacher

    Michael was born and raised in Phoenix, AZ. Michael was a short sprinter in college at a small Division II school in western Nebraska called Chadron State College. During his time at Chadron he earn several All-Conference honors as well as becoming an NCAA All-American placing at the National Meet in the 200 meters. After receiving his Bachelor's Degree in Education he moved on to Adams State College in southern Colorado to become a Graduate Assistant Coach with the track and field program. While at Adams State he was responsible for writing the in and out of season training programs for the sprints, jumps, and hurdle groups; including strength training, technical training, and conditioning. During his time at Adams State he coached several NCAA National Champions, over 20 NCAA All-Americans, and was part of a team NCAA Division II Indoor Track and Field National Championship. After graduating with his Master Degree in Sports Administration he returned to his home state landing a teaching and coaching job at Catalina Foothills High School in Tucson, AZ. Michael has been a Physical Education and Health Teacher at Catalina Foothills since 2012. He is also the Head Track and Field and Head Girls Cross Country coach at Catalina Foothills and has even coached Girls Basketball for a few seasons. Since he started coaching at Foothills he has won 3 State Titles, Coached 5 individual State Champions, and has been named the Southern Arizona Coach of the Year 3 times for Cross Country and Track and Field. Michael has been a member at CrossFit 646 for several years after his wife introduced him to Matt and Mel. Michael loves how CrossFit trains him not only physically but mentally which is very similar to his track and field and running backgrounds. He also enjoys how CrossFit prepares people for functional movements and whatever life might throw at you. When Michael is not at the gym he enjoys spending time with his wife RoseMarie and their 2 dogs Jeter and Miles.