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“Some of the principles that guide the Pilates method include concentration on each movement, use of the abdomen and low back muscles, flowing, precise movement patterns and controlled breathing,” explains the Cleveland Clinic. Pilates can be done on both a mat and a reformer, which Williams uses in the video.

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While generally known as an exercise to lean you out, Pilates is actually considered a form of strength training. While it doesn’t focus on building muscle, it does help improve muscle tone and help with stability and endurance. “Pilates isn’t going to bulk you up — if anything, it’s designed to cultivate a longer, leaner look,” explains the Cleveland Clinic. “Still, it can lay a strong physical foundation for muscle-building activities — and may even reduce your likelihood of injury.”

There are many benefits to doing Pilates, according to the Mayo Clinic. It “strengthens the body’s inner core while increasing its flexibility resulting in improved overall health,” they say. It can also promote longer, leaner muscles, injury prevention, relief from stress and back pain, enhanced athletic performance, and heightened mind-body awareness.

Pilates is a research-backed workout, Pilates exercises are designed to increase muscle strength, endurance, and flexibility, and to improve posture and balance, according to science. df44d9eab23ea271ddde7545ae2c09ec

In a 2010 interview with Vogue, Serena discussed why she does Pilates. “When I’m not playing tennis, I like to do yoga and Pilates…I don’t like to run,” she revealed.