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About Us


Nellie Brook, Founder of Mixx


After earning her Master of Arts degree in exercise and sport science from the University of Sydney, Nellie spent 14 years developing and providing Pilates programs for people with specific medical requirements, such as patients with chronic back pain, spinal stenosis, hip and knee replacements, and more. She spent 6 years as the Pilates department manager for Fitness and Wellness services in New Jersey, and operated her own Pilates studio in Sydney, Australia. Now she’s bringing her years of experience and care to California, to help you achieve your goals.

Aisling Macmillan, Instructor



Aisling has been teaching at MIXX since our opening. She began practicing pilates to eliminate the aches and pains caused by more than 15 years of competitive crew rowing in the UK. She's originally from Ireland but has lived in several countries. Upon leaving her legal career in the UK to travel, she found herself without a pilates instructor, so she completed comprehensive trainings in mat and apparatus from schools in the Netherlands and California. She also became interested in pilates for breast cancer recovery after completing the Pink Ribbon Program in post-operative workouts. Outside of Mixx Fitness, Aisling can be found exploring on her bicycle or drinking coffee.

Smadar Sweiry, Instructor



Smadar is coming to MIXX with 10 years of experience in teaching Pilates. She was first interested in Pilates because of her own back problem and was amazed to learn how Pilates improves injuries and posture. In 2011, she was licensed as a Pilates Mat Instructor and taught in Israel before moving to California in 2013. She is STOTT PILATES Certified, a mother of two, and enjoys staying active with Pilates, hiking, and yoga.

Christy Kirkpatrick, Instructor


Christy was born and raised in Bozeman Montana. She left at an early age to train at the Joffrey Ballet School and fell in love with Pilates through her mentor at ballet school. Pilates and ballet have been an instrumental force in her life since she was very young. After dancing with Milwaukee Ballet and the SF Opera Ballet she chose to end her dance career and get a degree in social work at San Francisco State University. After graduating from SFSU, she found a new passion in working with women recovering from chemical dependency. While working at a treatment center that focused on mind, body, and spiritual connection to overcome addiction and trauma, Christy became passionate about bringing Pilates to people who might not have the resources to experience the wonderful benefits of Pilates. She lives in Los Altos with her husband, two young sons and Nutella, her adorable golden retriever.

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Katie K. Griffin, Instructor

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Katie K. Griffin is a Bay Area Dance Artist. With over 34 years of dance experience and 26 years of teaching throughout California, she offers a unique approach to her instruction that opens the minds and bodies of her students in ways they’ve not experienced before. Katie holds her Bachelor of Fine Arts in Modern Dance with an emphasis in Modern Dance Performance from California State University Long Beach. She's an instructor for the Dance for Parkinson's community, and has recently added Pilates to her credentials. She holds her certification in Plant Based Nutrition from Cornell University and is currently delving further into body work and movement studies.

A note from Nellie:

I created MIXX after years of exploring, studying and teaching different training and exercise methods.

As a mom of three  and a wife to a super busy husband with my own career ambitions, I always tried to find the complete program that best fits my (changing) body and my (busy) mind, as well as my schedule, life priorities and most importantly... my budget. Workout by workout, through struggles and success, I created the MIXX concept. 

I am so happy I now get to share MIXX with you! It’s a revolutionary method, yet simple and focused on helping you reach your own goals for mind and body.

See you at the studio!


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