201 Oak Street Pembroke, MA 02359     |     781-319-7154     |     info@crossfitmagnitude.com     |       Facebook   Twitter   Instagram

Christopher O’Brien – Owner/Head Coach/Programmer


Chris has been passionate about sports and fitness for his entire life. With over 20 years experience training with functional movements, a degree in Exercise Science, an Infantryman in the US Army,  and over a decade working with people from all walks of life, Chris has developed the skills necessary to guide others in their quest towards greater fitness.

CrossFit and Chris were first introduced after a night browsing the internets fitness forums. The following morning, Chris decided to complete his first workout called ‘Fran’, a well known ‘Benchmark WOD’ by the CrossFit community, and found himself pale, disoriented, and gasping for air afterwards. With a less than desirable outcome, Chris began to question his current approach to fitness. From that day on, Chris has entrenched himself with understanding, implementing, and teaching others the fundamentals of the CrossFit methodology.

As a former U.S. Army Soldier, extreme outdoorsman, and avid CrossFitter, Chris believes that any individual seeking to enhance all aspects of their life, both mentally and physically, can do so by making CrossFit a part of their liftestyle.

Chris is looking forward to sharing his love of fitness with you through fun, inspiring, and educational workouts that will help you reach your goals!


  • Bachelor of Science in Exercise Physiology
  • Certified CrossFit Level 3 Trainer (CF-L3)
  • USA Weightlifting Sport Performance Coach
  • CrossFit Strongman Instructor
  • CrossFit Kettle Bell Instructor
  • CrossFit Judge
  • The Movement Fix Coach’s Workshop attendee under Dr. Ryan DeBell
  • A.C.E Certified Personal Trainer
  • CPR/AED certified
  • Military background


Jami H. (Miss Awesome) – Coach

Jami has been a South Shore girl her entire life, calling the 7-mile peninsula of Hull her hometown.  Growing up in the very (VERY) small town, she stayed busy playing baseball, soccer, cheerleading, and singing.

Her love for lifting weights started as soon as any of her friends had a license to drive to the closest gym.  She started with group classes but quickly found herself as the only girl in the weight-room daily and loved it.  From then on, she was a self-proclaimed gym rat, at one point having memberships at three separate facilities.

Her education and work experience led her to full-time employment at Reebok Headquarters, where she has worked in Logistics and Footwear Quality for the last 5 years.  It was at Reebok, during an all-employee fitness event, that Jami was introduced to CrossFit.  She completed a bodyweight WOD of pushups, sit-ups and squats with 400 of her closes Reebok friends and smiled the entire time.  She signed up for On-Ramp/Foundations at Reebok CrossFit One that very same day.

Having an employee box on the Reebok campus provided endless opportunities to learn, train, and become part of the amazing CrossFit Community.  Jami completed her Level 1 Seminar and began her coaching journey at RCF1, shadowing and learning from some of the best athletes and coaches known to the sport!  She continued coaching outside of Reebok, most recently landing her in the wonderful Magnitude community!

Jami is usually smiling, laughing, or singing; sometimes all at the same time.  She loves the ‘fun’ part of CrossFit, like thrusters!  No, just kidding!!  Her favorite CF moments include throwing around heavy weight, high-fives, The Filthy Fifty, slow claps, and the feeling of pride after helping someone do something they never imagined they could!

  • CF-L2 CrossFit Trainer
  • CF Gymnastics
  • BA Criminal Justice; UMass
  • MA Organizational Management; Ashford University

Derek S. – Coach


Derek is a 16-year veteran of personal training and coaching. Derek has completed 2 Ironman competitions, the NYC Marathon and several shorter endurance events. All of that endurance training along with a traditional strength training routine left little time for anything else in life. Looking for a more efficient way to accomplish his goals Derek found CrossFit. With all elements of fitness incorporated in CrossFit workouts Derek is able to cut down his training time while still improving his speed and strength.

With an extensive background in education,  Derek has the dedication, knowledge and experience to help athletes of all levels and abilities reach their fitness goals.



  • CF-L1 CrossFit Trainer
  • American College of Sports Medicine CPT
  • USA Weightlifting Sport Performance Coach
  • CrossFit Endurance Instructor
  • Level 1 USA Track and Field coach
  • Bio-signature Practitioner
  • CPR/AED Certified
  • Trigger Point Therapy Certified
  • Post rehabilitation (shoulder, knee, spine) Certified
  • Pre/Post natal Certified 


Laurie L. – Coach


  • CF-L1 CrossFit Trainer


Caitlin C. – Coach



  • CF-L2 CrossFit Trainer
  • CrossFit Kids and Teens Instructor
  • CrossFit Endurance
  • CrossFit Nutrition
  • Institute of Integrative Nutrition Holistic Health Coach
  • 5x Boston Marathon Runner
  • ACSM Certified Personal Trainer
  • Madd Dogg Athletics Spin Instructor
  • CPR Certified


To get started with your FREE Intro – Click HERE! 

If you would like to set up a one on one personal training session with one of our experienced Coaches, please contact Chris at info@crossfitmagnitude.com or call 781-319-7154.