Through all the twists and turns taken by Stacy "Fergie" Ferguson during her 20-year career as an entertainer -- including a stint on Kids Incorporated, background vocals for Martika, two albums with adult contemporary/dance-pop group Wild Orchid, and superstardom with Black Eyed Peas -- she has always sounded as if she is trying really, really hard.

That has been the lone consistent characteristic of her output, and it remains in effect throughout The Dutchess.

An endurance test like few other pop albums issued during the early 2000s, The Dutchess has all the characteristics of a release fronted by someone who has been itching to go solo and prove herself, once and for all, as a versatile force all her own.

Fergie does cartwheels and handstands, juggles three objects at once, balances books on her head, hangs upside down, rides a unicycle with her hands in the air -- all these things while wearing different outfits.

The whole process, produced mostly by fellow Pea will.i.am, is mildly entertaining but tremendously taxing.

There's throwback hip-hop ("Fergalicious," done to the tune of J.J.

Fad's "Supersonic"), throwback soul ("Here I Come," done to the tune of the Temptations' "Get Ready"), reggae ("Mary Jane Shoes"), ska-punk ("Mary Jane Shoes"), scat ("Mary Jane Shoes"), vaguely torchy midtempo fluff ("Velvet"), and a classy string-drenched ballad (the appropriately titled "Finally"), among several other passable switch-ups, but none of them has any lasting (or even immediate) value, with the possible exception of the inexplicably asinine "London Bridge" -- which is terrific, provided you can block out the lyrics or prevent yourself from trying to decipher its meaning.

Somewhat ironically, one of the more convincing songs on the album, "Big Girls Don't Cry," sounds exactly like a 2006 version of Wild Orchid, with Fergie's Taylor Dayne kid-sister act in full effect.