Threshold

Target: 1M warm up, 3M threshold, 1M cool down.

Threshold = 85% working HR (RW article). Working HR:

Resting = 52
Theoretical max = 206 - (0.9 x age) = 180
180-52 = 128
85% of 128 = 109
109 + 52 = 161

Actual HR: 155-165 during warm up, 170-180 (!) during threshold, 165-170 during cool down. I think I need to derive my max HR by practical means, not the formula.

Didn't check time at 4-mile point but at 4.6 miles it was 43:30, or 32 mins for the 3.6 miles of effort which equates to about 8:40 per mile. Total time 50:40 for 5.4 miles or 9:22/mi average. I'm really happy with that! The threshold run was as comfortable as it could be for that speed, and it did include the nasty little climb on Intwood Road, a steady climb on Colney Lane, and the biggish hill just before the Watton Road junction.

Route