Typically, rowers have enlarged hearts (also known as physiological left ventricular hypertrophy), allowing more efficient pumping of blood. 

Maximal intensity	Stroke volume (mℓ ejected from the left ventricle/beat)	Heart rate (beats/minute)	Cardiac output (mℓ ejected from the left ventricle/minute)
Untrained	150	220 minus age	20-30
Professional Rower	200	220 minus age	30-40

Fig. 10   Difference in cardiac output between trained and untrained individuals

What if we could enhance this further? Conversations surrounding growth hormones often occur when talking about athletes, but IGF-1 is the real player. Once initiated, a reaction cascade occurs—ultimately leading to protein synthesis, growth, differentiation, and survival of cells. There could be a potential 7.3% increase in muscle mass and a 12.2% increase in tetanic tension over 12 weeks of IGF-1 administration, accompanied by resistance training. This would benefit our rower massively by further increasing the cardiac output, thus increasing the volume of oxygenated blood reaching the tissues, resulting in a higher VO2 max.

Instead of using temporary injections or sprays, we could programme ourselves to make more. Gene doping is already being tested for the treatment of DMD, so it is a safe assumption that by 2028 it will be safe for athletes to use.

Fig. 11   Gene doping technique comparison