Aerobic Capacity

I have just finished reading Thomas' post, Rebuilding, where he ponders the proper weekly mileage for optimum marathon training.  I unfortunately, but deservedly, hold the honor of "what not to do" in the post.  If I can't inspire confidence, at least I can inspire restraint.

 

And since I like to talk as much as the next guy and seeing how Mike posed the rhetorical "optimum vs. maximum" discussion question in a comment, I thought I'd submit some thoughts about that topic.  

 

Lydiard's Mileage Chart of roughly 102 miles split amongst the days of the weeks as follows:

 

22 Sun

15 Mon

10 Tue

15 Wed

12 Thu

18 Fri

10 Sat

 

And with varying intensities as:

 

¼ effort Sun

¼ effort Mon

½ effort Tues

¼ effort Wed

½ effort Thu

¼ effort Fri

¾ effort Sat

 

Has been followed by many in order to improve aerobic capacity.  This is known as the marathon base building phase of the Lydiard training cycle.  It is the longest and most beneficial phase of the training regimen.  However, it should be duly noted that to adequately peak for the goal race (which was Lydiard's point) one does need to follow the rest of the program (hills / speed / race prep / taper).

 

Myself, I have only been concerned with this 'base' phase since I feel my aerobic capacity is no where near its potential and should remain my main concern for years to come.

 

It has been written that improving one's aerobic capacity is the cornerstone to improved race times and lays the foundation for future improvement.  Many proper analogies exist – building a skyscraper is one (Duncan).  Paraphrasing Mr. Larkin, "the penthouse is where the speedwork is, but the actual height of the building is the result of all the base building miles that took years and years to build."

 

Lydiard indicated, and I believe others have shown, the ability to exercise anaerobically is limited and that limitation is fairly consistent from person to person.  However, reaching one's potential to exercise anaerobically requires intense exercise for a period of 4 to 6 weeks that can break down a mere mortal.  After this short period, the maximum benefits of this training are realized and must be acted upon in a performance setting before the training 'fades'.  It can be reclaimed through additional exercise after an appropriate resting period.

 

But there is a limitation here – the very maximum performance that can be obtained is a function of the base aerobic capacity.  This is because once the maximum benefits of anaerobic training are obtained, the performance gains are added to the present ability to exercise aerobically.  Therefore, it is the person's unlimited ability to improve his or her aerobic capacity that can vault the runner into new realms of racing fitness.

 

There is no doubt however, that most of us, if we chose, could improve our present fitness dramatically (and in short order) by choosing a 4 – 6 week anaerobic training regimen.  We would be taking our present aerobic capacity to exercise and adding an additional capacity to exercise anaerobically.  These two together would produce some relatively outstanding performances.  Relative being the key word – our performance would be relative to our current aerobic condition.

 

Lydiard was a long-view coach.  While incorporating peaking mechanics into his training cycle, he nevertheless became famous for putting much time and effort into convincing people to run aerobically for a long, long time.  So when people say they are running "Lydiard", they most often are referring to the base phase of the multi-phase Lydiard program.  If you haven't mastered Lydiard's superb aerobic capacity building phase yet, then the time-value approach biases toward continuing with the base phase "as long as possible".  The benefits are enormous.

 

But here's the sticky question: Just how many miles should I run?  The answer: All of them.

 

A quick read of Lydiard's writings and we find that his runners routinely ran "aerobically" at 6 minutes per mile.  This meant that on a ½ effort day, they could cover their 10 miles in about 1 hour.  This correlates with another schedule Lydiard proposes based on time instead of miles.  In fact, he suggests using the time schedule as an introduction to approaching the high mileage:

 

2:00+ Sun

1:30 Mon

1:00 Tue

1:30 Wed

1:00 Thu

1:30+ Fri

1:00 Sat

Weekly total: ~570+ minutes.

 

His runners were already very fit and needed coaching to maximize their aerobic potential.  In order to maximize aerobic capacity, Lydiard proposed running at or approaching the aerobic threshold on a daily basis – thus his varying time/miles and intensity schedule.

 

If we assume Lydiard was correct in his time/mileage assessment for building optimum aerobic capacity in a training regimen, and if we assume that his varying daily intensity corresponds to a maxHR training regimen such as:

 

¼ = 75% maxHR

½ = 80% maxHR

¾ = 90% maxHR

 

we can re-list the schedule in terms of minutes x % HR or HR Time Units:

 

9000 HRTU (Sun)

6750 HRTU (Mon)

4800 HRTU (Tue)

6750 HRTU (Wed)

4800 HRTU (Thu)

6750 HRTU (Fri)

5400 HRTU (Sat)

 

A total week of HR time units = 44250, an average of 77.6 HR time units per minute or rather, running at an average of 78% maxHR.  Now if we use Lydiard's limit of 100 miles for his runners running the above schedules, then the optimal pace at 78% maxHR is 5:42 per mile.  [44250/100 miles = 442.5 HRTU per mile / avg 77.6 HRTU = 5.7 minutes/mile].

 

So if we are still running under 5:42 per mile at 78% maxHR, then there is no reason to run the 100 miles per week because most likely we can't do it at optimum paces (proper heart rates) and therefore not receive an equivalent aerobic benefit.

 

Or can we?

 

Let's say that following the above HR schedule a runner netted 85 miles for an average 78% maxHR pace of 6:42 per mile.  He ran a total of 44250 HRTU's, just like Lydiard's pupils, just slower.  Thus he achieved optimum aerobic capacity training for his ability.  But can we choose to run at lower intensities and still obtain optimum aerobic capacity benefit (defined as 44250 HRTU per week)?  Or what if our conditioning doesn't allow our bodies to run at such HR intensities without breaking down?  Can we still shoot for 44250 HRTU per week?

 

Yes we can…  A quick look at a recent run of mine says my 60% maxHR pace is 8:41 per mile.  At an average pace of 8:41 per mile, I'd hit 44,250 HRTU at exactly 85 miles.  But it will take me 23% longer (2 hrs 48 mins) to get the same aerobic improvement (relative to each runner's respective starting point).

 

This is the beauty of training.  We each find ourselves in different circumstances relative to our level, weaknesses, drive, etc.  Yet, if we put in the time, at a corresponding level of effort, we can still achieve great improvements from where we are – even if we aren't running "hard" every day.

 

On the other hand, you can easily see that the runner running "optimum" paces has many advantages:

 

1.                  Has time to train (takes less out of the day)

2.                  Probably less prone to overuse injuries

3.                  More likely to meet the weekly optimum

4.                  And more able to increase his time running if he so chooses (beyond 44250 HRTU)

 

Lydiard did mention as an aside that those deciding to run longer to reach the weekly mileage goal probably "achieved greater aerobic improvement".  This is because their HR is elevated for longer periods of time thus accumulating more HRTU's.  For example:

 

The optimum pace runner accumulates 44250 HRTU's per week.  The 60% HR runner @ 8:41 per mile would accumulate 52,100 HRTU's per week if he ran the full 100 miles.  (The other runner only running 85 miles) Thus, barring injury, he would make great strides in personal aerobic development and at a faster rate than the "optimal" runner.

 

But injury is the catch.  How long could the runner withstand such intensity of time on feet?  And when calculating risk vs. reward, can we assume linear marginal improvement beyond Lydiard's schedule or should we assume a degree of diminishing return for every HR time unit beyond 'optimum'?  The latter is the most widely suggested with good empirical evidence (my blog for example).

 

My assumptions for the above:

 

·                    Lydiard's schedule representing "optimum" level of training therefore establishing a point of diminishing return

·                    Practical maxHR % correlations

 

This doesn't address issues particular to the slower runner – one being fuel efficiency beyond 2 hours.  The runner running slower in training but still following the reduced Sunday time (2 hours) may run into some unfortunate surprises late in a marathon.