Before revision: 6 – No exertion at all, relaxed 7 – Extremely light 8 9 – Very light 10 11 – Light 12 – Moderate 13 – Somewhat hard 14 15 – Hard 16 17 – Very hard 18 19 – Extremely hard 20 – Maximal exertion The scale was constructed to roughly correlate to 10%DIF > of heart rate in a healthy 20-year-old.
After revision: 6 – no exertion at all, relaxed 7 – extremely light 8 9 – very light 10 11 – light 12 – moderate 13 – somewhat hard 14 15 – hard 16 17 – very hard 18 19 – extremely hard 20 – maximal exertion The scale was constructed to roughly correlate to 10%DIF > of heart rate in a healthy 20-year-old.