In his athletic debut at the age of 15, Jim Ryun, the extraordinary talent in middle distance running back in the 60's, could not do better than 5'38" on the mile.

Only six months later, with an unfocused training approach, he ran in 4'26". At the end of that season, he did 4'08".

At that point, convinced by his coach Bob Timmons, he decided to get serious: he increased his training loads exponentially during the winter and the following year, in his second track & field season, he managed a sensational 3'59" on the mile, which earned him a spot at the Tokyo Olympics, when he was only 17 years old!

Two years later, in 1966, he ran in 3'51"3, a new world record, further improved one year later to 3'51"1, a record that held for 8 years.

Ryun is the paradigmatic example to explain the concept of TRAINABILITY, a quality that only great athletes express at the highest levels.

Similarly to the case of altitude training, there are "high responders" and "low responders" to the same stimulus.

Surprisingly the margin of improvement has nothing to do with the initial performance level.

​

Tony Rominger started cycling at the age of 21. Until then he had not practiced any sport, and led a sedentary lifestyle as an accountant. Put on a bike casually by his brother, he propmptly showed his qualities, with rapid improvements that convinced him to go pro, albeit being almost 25 years old.

Despite the lack of "cycling school" experience, amazing and steady performance progress allowed him to become one of the best cyclists in the world in the 90's, mainly thanks to his ability to withstand large training loads.

​

An increased DIASTOLIC FILLING, that phase of the heart rhythm in which the ventricular cavity relaxes, filling the effluent blood from the periphery, appears to be involved in quantifying the degree of trainability.

The TOTAL VOLUME OF BLOOD (red blood cells + plasma) determines the extent of diastolic filling.

Obviously, those athletes who have a better training response are the ones showing a better increase in blood volume in response to the workload.