Tennis champ and fashion designer Serena Williams recently showed off her seriously impressive bikini body while on a one-day vacation from her very busy life.

The 35-year-old flaunted her itsy-bitsy bikini while sitting poolside. The photo highlighted her very impressive back muscles and slim waist.

In addition to her toned waist and back, Williams is also known for her muscled arms and incredible upper-body strength. The good news is that you can achieve a similar level of upper-body strength without having to swing a tennis racquet.

Williams’ Nike master trainer Marie Purvis has helped create a workout for her, which is featured in the Nike+ Training Club app. It’s free on Apple’s App Store and the Google Play Store.

To power her workouts, Williams consumes green smoothies with protein powder and veggies like kale.