Probably a sidebar, mostly lost in history, but the BUB #61 jockstrap, previously issued to WWII Navy pre-flight school cadets made an encore appearance during the Vietnam War draft. After the the TET offensive, the Army found itself in dire need of replacement infantry troops. Enlistments were down, and Selective Service could not deliver adequate number of draftees. The Pentagon instituted a program called P-100,000 designed by Sec. of Defense Robt. McNamera. What it basically involved was eliminating all height, weight and most mental standards which had previously disqualified potential draftees. The Pentagon felt that if the Viet Cong could have 80 lb. couriers carry 100 lb. bags of rice, or other military assets hundreds of miles on their backs, the Army should be able to toughen up some 90 lb. weaklings to be combat soldiers. The whole concept failed, as the basic training drill Sgts. spend so much time on the physically unqualified draftees, they couldn't get the remainder of their platoons ready for graduation on schedule . The solution of the Army was to establish special physical training programs at several recruit bases to "toughen up" these special draftees before they were assigned to a basic training company. This occurred when I was completing my senior year in college, and the professors were quite opinionated that the Army method of exercise overload was entirely the wrong thing to do.
Among several other special training units, the Army sent overweight draftees to Ft. Polk in Louisiana, the mental problem draftees went to Ft. Knox and the small and feeble draftees were sent to a company at Ft. Leonard Wood, Mo, the location where I would do basic two years later. I was more informed about this training program for small draftees as my roommate was researching the program for his masters thesis, but was refused access by the Army to personally observe the special training company. Manpower needs meant that a good many of these small draftees would be assigned to combat infantry, so the Army took some drastic measures to put enough meat on their bones tht they would have a fighting chance to survive in combat, and not endanger other troops. For this reason the Army program was nicknamed "Operation Runts into Grunts" The special draftees did physical training all day, 6 days a week. They were literally exercised until they collapsed, then attended by medics on site whose job it was to see how quickly they could get them back into formation doing more PT.
The Army figured they needed jockstraps and each draftee was issued three jocks, one to wear, one to wash in the barracks washing machine and one to dry hanging on the bedpost of their bunks. I don't know all the details, but the quartermaster command knowing that they needed heavy duty jocks for all day wearing apparently went to Chicago and St. Louis and purchased all remaining stock of small BUB jocks for the recruits.
Some of these special recruits had been home schooled, or attended private religious schools and had never beeen in a physical education class, or for that matter never worn a jockstrap before. The BUB jocks were serious jockstraps, which held the "man parts" of each recruit firmly in place all day, so I am sure some of these recruits found their "jock training" to be almost as challenging as their abusive physical training.