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Weightlifting & Exercise/What muscles are used in this activity?


Hi Karen,

I have a question that might be a little different from you usual questions, but I thought I would give it a shot.
I am trying to design a child proof package for an electrical device I have built, and I am interested in which muscles and/or what types of strength measurements would be used in this situation.
I have a really small device about the size of five pennies stacked together. It has batteries inside and I don't want little kids opening it up. The plastic cover comes in two parts that snap together. When someone needs to open the cover to change the batteries, they grip each end between thumb and forefinger (imagine gripping the top two pennies with one hand and the bottom two pennies with the other) and pull apart. Can you tell me what muscles are at work in this action?
I have found a lot of data on average Pinch Strength for women, men and children. Is pinch strength the only strength value that is relevant in this case, or would the strength in the wrist that pulls the two parts of the cover apart also have an effect?
Sorry if this question is not in your area. Thanks in advance for reading my question, and thanks for volunteering here!

Best regards,

This is actually out of my expertise because it is the muscles of the hand and arms.  I recommend you try to find an orthopedic surgeon who specializes in hands.  Make an appointment to see him or her in their office.  Hopefully you will find someone willing to help.

Good luck!

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Karen Fili Sullivan


Get on the inside track with Karen and her daily advice. Or on FacebookLIKE us at ZWL - Zen of Whole Living I have more than 30 years experience and can help with lifting technique, muscle recovery, weight loss, body building and powerlifting. I've been certified by AFPA as a Personal Trainer and 12 years ago acquired a second certification from the same agency as a Post Rehabilitative Exercise Specialist. Any recommendations or advice rendered are based on fitness information as specified by the American College of Sports Medicine and the American Fitness Professionals and Associates. Follow my Blog on


Almost 25 years coaching and training. Wow! I feel old. Before that I was a competitive bodybuilder and powerlifter (ask my Chiropractor -- he can tell you). I have trained kids ages 12 to 89. From sports specific training to stroke rehabilitation. I love helping people move more gracefully, powerfully and safely.

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Published in Spring of 2013 The Zen of Weight Loss: A Mindful, Livable Approach to Fitness Get your copy at Square Market.

English with a Journalism concentration was my college education. My training has been with my mentor, Jack Michaels, ACSM and professor at the College of William and Mary. My certifications are with the American Fitness Professionals and Associates. AFPA. I hold a certification as a Personal Trainer and a Post Rehabilitation Exercise Expert (Isn't that a mouthful?l). My continuing education requirements have been fulfilled at a number of organizations and are monitored by AFPA. I keep my Red Cross CPR and First Aid current.

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Clients include athletes training for marathons, mountain climbing and general weight loss. In addition I have clients troubled with COPD, Fibromyalgia, and Parkinsons as well as stroke rehab. She was the Strength and Conditioning coach for Williamsburg Aquatic Club, a USA Swim Team, in Williamsburg, Virginia for 3 years.   Karen is presently working at Main Street Gym in Historic St. Charles, Missouri where she teaches Pilates and continues her work with clients. Her training reaches across the country with her long distance Body Restoration eTraining. Her dedication to fitness reaches into the nutritional supplementation with Shaklee products. She only works with clients who add nutritional supplementation to their training. Read more of her story on

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