@JoeBobMack
I'm just intrigued by the possibilities of stories using the idea of humans at maximum capabilities, operating at the boundaries of current human capacity, physical, cognitive, and emotional.
What are the "Maximum Capabilities" of human being?
I doubt that "science" nor scientists know.
The modern Olympics began some 125 years ago. Before the "Great War" (World War One 1914-1918) there were some very good athletes, but I am not aware of any Extraordinary athletes. Many of the Olympic competitors were military officers. Events, such as the Pentathlon (Running, Swimming, Horse Riding, Fencing and Pistol shooting) were based upon military skills. Fencing, shooting, and many of the athletic events were dominated by athletes who were also serving officers in their nation's armed forces.
After the Second World War the IOC (International Olympic Committee) made rules that were intended to limit the Olympics to "Amateur" athletes. These rules were intended to eliminate (most) military or naval officers, as well as professional athletes, such as members of the Premiere League footballers, the PGA golfers, MBA basketball players, and MLB baseball players, etc. However, the communist nations, and some other nations fielded state sponsored athletes. This resulted in some extraordinary, although hyper-specialized, athletes. Money is a significant factor in the development of these athletes. In many cases it was Government money, spent mostly for the prestige of the "records set" and "medals won" by the nation/Government seemingly more important than individual achievements. In Western nations some individuals with extraordinary potential benefited from wealthy patrons in their early teen years, or even younger. "Good fortune" allowed an extraordinary few youths to receive intensive training, diet, and other methods of development to become Olympic competitors.
A hundred years ago the military Olympians were mostly wealthy individuals, such as Lieutenant George S. Patton Jr., who were allowed the time to prepare and compete in the Olympics, but did so without any particular assistance from their governments. In the 1930's science and "pseudo-sciences" focused on human development began getting state (government) interest. There had been some dabbling since the 1800's. During World War Two there had been some government/military interest in developing "elite" or "Super Soldiers" but most of this was more erratic than systematic.
The USA and, to a lesser degree, the UK, had some flings at "developing a superior soldier" but devoted more resources, and had more successes in developing superior equipment and rations. Nutrition, physical fitness and training, and equipment development had been an interest since the early 1800's; however, material sciences and industrial production to mass produce such material didn't exist until WWII. The Soviet Union, Nazi Germany, and Imperial Japan, among others, dabbled in developing "Super Soldiers" or at least superior soldiers; however, much of this was twisted in myths of "racial superiority" or political dogma.
On a side note. During WWII US Army General SLA Marshal who was just supposed to be a historian, began research into the experiences of soldiers in frontline combat. Particularly Fear and Fatigue. While a rational person experiences some fear in danger, an unprepared person is much more likely to suffer greater fear. People can be trained to cope with stresses, and minimize fear. Combat is both physically and emotionally wearing; unnecessary burdens and/or exertions are likely to make people more vulnerable to emotional stress. Fear almost always results in reduced physical abilities. LTC Dave Grossman and others have made further studies beyond the observations of SLA Marshal.
(Tangent: SLA Marshal consulted with a US Army Medical Doctor about his theories of the relationship of Fear & Fatigue, and that proper training, and practical limits on weight of gear could improve soldiers performance. The doctor not only agreed with him, he told Marshal that if knowledgeable doctors were allowed to select the soldiers, AND those soldiers were only allowed to eat a scientifically developed diet it would multiple the beneficial effects of appropriate and realistic training and equipping of the soldiers.)
In any particular year, in the NFL there are some 1500 athletes playing American football, and a similar number in the Premier League playing soccer. 3,000 men drawn from a high fraction of the worlds population, and not all of them are at the same level. In any given year there are fewer than 20, perhaps fewer than a dozen men who a "Champion level" Quarterbacks. Similarly, Olympic Champions are fewer than One-in-a-Million human beings; nearly all of those champions are hyper-specialized.
Is that the limit of human potential? No!
The US armed forces have been on a trajectory since the 1930's of scientifically selecting, developing, training, feeding, and in other ways preparing and equipping their soldiers (sailors, Marines, aviators) for combat. Obviously far from perfect. By the late 1980's the USA had developed extraordinary military and naval capabilities; although not noticeably that different from their NATO Allies, nor even their Warsaw Pact opponents. Until, Desert Storm. The UK could field perhaps a dozen similar Battalion sized units, compared to the USA's 100 or so US Army and USMC (note these are Not all of either nation's armed force, just the units of superior quality that can be fielded; nor were all of those superior units involved in Desert Storm. The USA had probably 70 in theater and the Brits 6 to 8). Air Force and naval capabilities are of a similar nature. The UK has a couple of hundred individuals in the SAS and SBS, etc. compared to the thousands (many thousands) of "First Tier Operators" throughout USSOCOM. {The UK, Canada, Australia most benefit from extremely close relationships, in particular in the Special Operations community.}
Yes, South Korea, the Netherlands, the Scandinavians, French, the Israelis, and several other nations, not the least of which is the PLA of communist China also field competent armed forces, and well trained and equipped Special Operations forces. None come anywhere close to the results that can be achieved through "Cubic Money" honed by decades of combat and other operations. Money isn't everything, however, in the words of Soviet Marshal Zhukov, "Quantity has a Quality all its own." That does not mean that a unit of Chinese soldiers cannot defeat a similar sized US force. Nor does it mean the USA may achieve its political objectives with military force. The Finest Sword cannot repair a broken window, nor stem a flood.
The USA can select from a vast pool of volunteers, not just from the USA. Medical physiological and phycological examinations and development, a (generally) healthy diet, physical conditioning and other realistic training results in individuals who can perform a multitude of athletic feats of Olympic caliber, in addition to their military skills, also, many have language, cultural, medical, and other skills similarly developed. Although much of it is "Open Source" most people in the USA, or elsewhere, truly know, let alone Understand what many members of USSOCOM are capable of.
We are no where near the peak of what we are capable of, yet a very small percentage of us have developed nearly as much as they could. However, over the last hundred years the US armed forces have demonstrated that with good training and material even ordinary people may be developed to a much higher potential; and merely above average people may be developed to near "Olympic caliber" with a significant commitment of resources. According to the song: "Only Three Percent of those who test today will become Green Berets." It's more like 25% to 30%, since a bit more than half the people who apply for selection eventually pass; and a similar percentage will eventually pass the "Q-Course"
...Realistically, if we did not wish our Special Forces to be so "elite" a greater percentage of people could be trained to pass the standards!
I was never an "Operator" although I did serve in SOCOM. I witnessed the capabilities of these individuals at close hand (not just their combat abilities). During my career I did complete quite a few training courses, some of them quite intense. "Better Men" than I failed those courses, most often by quitting. By better I mean stronger, fitter, more athletic, etc.