What can influence a 'HIGHER' Heart Rate!
Warmer and certainly more humid conditions.
Poor gut health, ie; bad food choices.
Harbouring a cold or flu.
Signs a cold or flu is on its way.
An injury driving inefficient form.
A false flat (terrain).
Altitude - definitely this one.
What can influence a 'LOWER' Heart Rate!
Early morning colder sessions.
Over-trainning syndrome - this is not good!
Low blood pressure.
Unbalanced minerals, ie; sodium balance.
Metabolism switching from sugar to fat.
Your slept like a King - great sign.