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Lying French Press is one of the best exercises you can do to isolate the triceps. It is usually performed on a flat bench with an EZ curl bar but if a bench is not handy or you simply want to try something new, you can use a low cable with straight bar attachment and stability ball.
Start with your head and upper shoulders resting comfortably on the ball. Grasp the bar with both palms and elbows facing up towards the ceiling.
Inhale as you lower the bar behind your head trying to keep your elbows in the same position. You can lower the bar until your arms are fully flexed as long as you do not move your elbows.
Pause for a split second and extend both your arms without flaring them out excessively until your arms are fully extended and your triceps are contracted.

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