Katharine McPhee bares her taut tummy in a black sports bra and leggings as she does Pilates

Katharine McPhee showed off her toned tummy as she highlighted her workout routine on Instagram this week.

The 40-year-old singer — who is married to 74-year-old David Foster — used the app's Stories feature to upload video of her grueling Pilates regimen.

She was clad in a black Alo sports bra with white trim and coordinating skintight leggings.

The songstress skipped shoes as she used fitness equipment in a pair of white and black Alo Yoga socks.

McPhee wrote across a mirror selfie,'Thank you @marymillermethod @alo. Socks are my fav.'

Katharine and husband David share three-year-old son Rennie,who was born in February 2021 and joined Foster's five adult children

She explained: 'There's the more old-fashioned way of disciplining which involves time-outs and things like that.

'My take is that you can have more mindful parenting opposed to just assuming that a two or three-year-old can have time alone to reflect on what they've done poorly.'

The singer-songwriter added,'I think the more new way of parenting is understanding that with a child,there's only so much that they can intellectually understand.'

The couple met in 2006,when Foster served as a guest mentor on American Idol. 

They struck up a romance in 2017,and tied the knot in June 2019.

David FosterKatharine McPhee