low mileage

Got this e-mail from Matt Mahoney, who gained infamy two years ago when he missed the 48 hour finish line cutoff at Hardrock by 17 seconds. He lives in Florida and always takes on Colorado's toughest runs, sometimes doing hill training in parking garages because the terrain is so flat where he runs. He is 0-2 in his past two Hardrock attempts, but has finished it before with mileage like this:

A typical week for me is 20 miles running (including races), usually with a 10 mile road run on Sunday in 6 oz. shoes (7-8 min/mile pace), a 5K race in 4 oz. flats on Saturday (6:30 pace), an interval workout (e.g. 10 x 100 yd or 6 x 400 yd at 4-6 min/mile pace) barefoot on grass in the middle of the week, plus about 10 miles of walking (about half barefoot on grass or roads), 80 miles biking and one or two weight lifting sessions. About 10-12 times a year I substitute a marathon or ultra for my long run, or if there isn't one scheduled, I'll do a 28-30 mile run. I am male, age 53, 6 ft 0 in, 163 lbs. My best times in the last 2 years are are 5K in 19:15, half marathon in 1:32, marathon in 3:25, and 118 miles in 26:55 (wearing 5 oz racing flats without socks).