I'm going to resist the temptation to write about the serial stupidity of Rowan Williams
(a man who demonstrates the old edit that you can be brilliant and yet
lack any practical wisdom, although personally I blame his Marxist
politics) and regale you instead with the twelve worst fitness inventions of all time.

Actually, I can't help but be tempted to think this was made for Williams and friends:

THE PROSTATE-GLAND WARMER
What the hell was it? A nine-foot-long electric cord with a 4 1/4-inch butt plug on one end and a blue light bulb on the other . . . just use your imagination.
Debut: 1918
The promise: Upon insertion, the plug will somehow stimulate "the abdominal brain." It's working when the light bulb lights up.
Our verdict: Made your ass look like a blue-light
special. This is one invention you'd hate to have been caught
road-testing. Besides, adds Seabourne, "Your prostate is plenty warm to
begin with."

This sounds a treat too:

THE BATTLE CREEK VIBRATORY CHAIR
What the hell was it? A spasmodic seat that shook the sitter violently-until he relented and stood up. Conceived by Corn Flakes creator and bowel redeemer John Harvey Kellogg, this one was featured at his Michigan sanitarium.
Debut: Circa 1900
The promise: Being shaken, not stirred, will stimulate intestinal contractions and, therefore, leave you with a cleaner colon.
Our verdict: Sitters surely felt like Wile E. Coyote
on "ACME Earthquake Pills." Reminds us of English nannies and
baby-shaking scandals. "You might as well have sat on a hansom cab over
a back-country road," says Seabourne.

(via Aussie Dave at Israellycool)