8:00 a.m. - 8 miles easy.
This morning, while doing my 8 miles in around an hour, I was thinking about why 2 recovery/maintenance runs a day of an hour is perfect. Most of the top Kenyans run twice a day for an hour on their recovery/maintenance days. But that doesn’t mean that I should. Many elite ‘Western’ runners run twice a day, but tend to do something like a 12/13 and a 6/8/10. Then I remembered an article I read by Frank Horwill outlining one of the most important reasons for doing 2x1hr and not 1.5hrs followed by something else. Cytochrome c.
So what’s this stuff? Cytochrome c is a key compound found inside mitochondria and is imperative in aerobic energy production. Cytochorme c contains one atom of iron per mol and is a power-house of amino acids. Here 's what Frank had to say:
In 1982, Gary Dudley, at the State University of New York at Syracuse, investigated the effect of intensity on mitochondrial production. His work was painstaking – rats were made to run five times a week for periods ranging from five minutes to ninety minutes per day, for eight weeks at training intensities which ranged from 40 per cent through 100 per cent V02 max. Dudley examined how different speeds and durations influenced different muscle fibres (fast twitch, aerobic fast twitch or intermediate and slow twitch), which no one had done before. His findings were as follows:
Training beyond about 60 minutes per workout was without benefit in terms in increasing cytochrome c. Moving from 30 minutes to 60 minutes per session did increase cytochrome c, but not increasing the workout from 60 to 90 minutes. This was true of all intensities studied by Dudley – and also with all three muscle fibre types. Mitochondrial development ceased after an hour.
Training for 10 minutes a day at 100 per cent of the V02 max (about 3K pace(ish)) tripled cytochorme c concentration.
Running for 27 minutes at 85 per cent V02 max (about 10 seconds per mile slower than 10k speed(ish)), only pushed up cytochrome c by 80 per cent.
Training at 60 to 90 minutes at 70 to 75 per cent V02 max (marathon speed(ish)), edged up cytochrome c by just 74 per centt.
In intermediate muscle cells (those which are roughly half way between fast twitch and slow twitch), a similar potency of intensity was recorded. Ten minutes of fast running per day boosted cytochrome c as much as 27 minutes daily at 85 per cent V02 max or 60 to 90 minutes at 70 to 75 per cent V02 max.
The best strategy for slow-twitch, cytochrome c enhancement was running for 60 minutes per outing at 70 to 75 per cent V02 max (around 80 to 84 per cent of maximal heart rate), which boosted cytochrome c by 40 per cent.
Cruising along for 27 minutes at 85 per cent V02 max produced a 28 per cent upturn as described above.
Fast running at 100 per cent V02 max (3K speed), lifted slow twitch cytochrome c by around 10 per cent, not a surprising low gain because slow twitch muscles are less heavily used than fast twitch cells during fast running. However, running at this speed represents, for 10 minutes work, 1 per cent improvement per minute of running compared to running at 85 per cent V02 max, which lifted cytochrome c in slow-twitch fibres by the same 1 per cent per minute rate for nearly three times the duration of work. And, further, 90 minutes of 70 to 75 per cent V02 max work improved the mitochondria by just two-thirds of a per cent per minute.
Yes, there are benefits to running for longer than an hour but the law of diminishing returns kicks in, especially on recovery/maintenance days.
5:30 p.m. 6 miles, including 8x8 sec's hill blasts. Felt sluggish before the sprints but during and then after the reps I felt much better.
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