Question

what is the relationship between heart rate and workload

Answer 1

Both the duration and intensity of exercise is referred as workload. There is a linear relationship between workload and heart rate that means when workload increases, the hear rate also increases.

Increased workload stimulates sympathetic nervous system which have positive chronotropic effects (Increases heart rate) on heart. And also increased workload increases oxygen demand of the skeletal muscle that makes heart to pump more blood to meet oxygen demand by increasing heart rate

So, Both sympathetic sytem and increased oxygen demand increases heart rate when workload increase