The heart is made up of muscle components consisting of Troponin complexes & cardiac enzymes (CK). Injury to cardiac muscle releases these components in the blood stream & these components can be measured at time of injury to the heart.
Cardiac adaptations to increasing work load include cardiac muscle hypertrophy & physiologic dilatation to meet the increasing body demands.
The relative cardiac changes that include hypertrophy & dilatation is dependent on the training exercise resistance.
The heart adaptation includes cardiac output (CO) with VO2max (exercise intensity) therefore delivering an increasing blood delivery to the exercising muscle with more efficient energy system management.
CO = Stroke volume (SV) x heart rate (HR)
VO2max = CO x (arterial O2 – Venous O2)
With improving fitness levels the heart delivers more blood at any given pre-adaptation exercising work load.
The peripheral adaptations in the muscle facilitates the improving blood delivery by adaptations that include improved energy utilization at an given exercise work load through improved energy efficiency.
The heart rate responds to any workload that can be measured serially to assess fitness levels during, and especially after a standardised exercise testing session.
