Hi Neil,
Below is your HIIT program to do at home on the days you do not ride or run.
1. Skipping for 45 seconds: Heart rate needs to hit maximum in this time. Rest 1.5 minutes then repeat 3-4 times
2. Running up stairs for 45 seconds: Make sure your whole foot is on the step. Walk down slowly and wait the remainder of 1.5 mins then repeat 3-4 times
3. Sprints on grass: Sprint 30 seconds rest 1.5 mins then repeat 3-4 times