World Cup
 

You're right (see Bobby Moore 1966) and I can understand why CD gets so frustrated with all the physiological excuses (it's like tv. commercials telling us that the use a certain brand of toothpaste is "technically proven" to "protect" our teeth and give them a longer life).
I am not such a Luddite as not to understand the importance of neoprene in the development of wetsuits for example, but we shall soon be hearing that the Nike swoosh on your trainers gives you just that extra edge in athletic competition!
(and the period you refer to was of course also a time when the boy racers loved to apply go-faster stripes to their cars).

On a practical note of clothing fashion, women's dress hemlines rose during WWII simply because the extravagant use of scarce materials was to be avoided.

On the subject of jammers, there was a bike race along the waterfront here in San Francisco and some of the competitors came in a super market.

There was a guy wearing what I call "short jammers" -IE- spandex athletic shorts that went only 1/2 way down from the knees.

There was a logo "Iron Men" on them however I don't know of that's their brand or something else.

Stay tuned.

Doesn't explain why female long distance runners wear very brief shorts.

Possibly jammers would be better for swimming in cold water, to keep your legs warmer?