Re-examining the components of base building

Spring has become summer.  By mid-morning yesterday, the overnight clouds had given way to blue sky and bright sunshine, and I was eager to be running.  However I was tired after a heavy week at work, with late nights and relatively little sleep, so I opted for a relaxed lower aerobic run though the woods and along the river bank.  It was a delight to be out of doors.  In the woods the prominent flowers are now red campion and buttercups where only a few weeks ago celandines and bluebells were dominant. I felt comfortable focussing on maintaining relaxed good form, but whenever I tried to increase pace, I my legs felt heavy.  I covered 18.5 Km at a pace of 5 min 56 sec per Km, and a mean heart rate of 112.  Despite enjoying the run, the question nagging me at the end was whether or not my sluggishness could be accounted for entirely by a heavy week at work.

This morning it was even more tempting to be out running.  The sun was again shining brightly, while the woods and riverside were still fresh, green and inviting.  I decided to repeat yesterdays run, expecting that I could improve on yesterday’s sluggish pace without strain.  But again my legs were reluctant to cooperate.  I concentrated on keeping my hips forward attempting to conjure a brisk lift off from stance, while aiming for a feeling of fluency rather than effort. But there was little spring in my legs, I was still sluggish in getting airborne, and my stride remained short.  Checking my heart rate monitor revealed that my pulse was a little higher than yesterday, but my pace over the first 15 km was virtually identical.  In the final few Km, in an effort to break out of the state of torpor, I focussed on the downwards thrust of my arm as my foot lifted from stance.  This shift in focus was more successful in bringing my foot up briskly, and I built up pace so that  the final 3 Km was about 2 minutes faster than yesterday, with little increase in subjective effect.  Nonetheless my average pace for the entire run (5:50 per Km) was only 6 seconds per Km faster than yesterday, and my mean heart rate 118, compared with 112 yesterday.  In terms of heart beats per Km, today’s run was even less efficient than yesterday’s.

In several respects the two runs this weekend have been a success. I have enjoyed being out of doors in delightful surroundings and I managed to cultivate a relaxed and fairly fluent style despite sluggish legs.  But apart from the final few Km today, in which I managed a pace of around 5 min per Km, my pace was unimpressive.  Am I making progress or have I become stuck in a rut?  Is there any point in drawing conclusions from runs in the lower aerobic zone?  In fact I think there is much to be learned from back-to-back easy long runs, and the conclusions I would draw from this weekend are in fact positive though tentative.  But in order to appreciate this, it is necessary to review the essential elements of fitness for distance running.


Building a base involves more than increasing aerobic capacity

Since the very influential work of Jack Daniels in which he delineated various training zones extending from lower aerobic to anaerobic based on the proportion of energy derived from the different energy generating metabolic pathways, much emphasis has been placed on the development of aerobic capacity – the amount of energy that can be generated by oxidative metabolism of glucose or fat.  As races over distances ranging from 10Km to the marathon are fuelled largely by oxidative metabolism, this is doubtlessly a key concept, but there is a danger that focus on aerobic capacity distracts from the fact that base-building has several additional components. 

Each individual has a range of strengths and weaknesses depending on genes and life experiences, and each individual runner needs to establish what are the limiting factors for him or herself.  In contrast to my younger self, I now find that getting fit is a slow process.  What is so different in my mid-sixties compared with my teens and twenties?  The most obvious fact is that four or five decades ago I was still in a phase of natural development, whereas now my strength is declining as anabolic hormone production decreases and body tissues lose their resilience.  However, the inevitable decline with age is only part of the story.


What was the foundation of my fitness 40 years ago?

Another part of the story is the nature of my fitness base.  As an 8 year old, I simply regarded running as the natural way to get from one place to another. I ran to school; I ran to the shops; I ran everywhere.  As a teenager, I played football for many hours each week and I still preferred to run than to walk.  In my twenties, I loved being in the mountains, walking or climbing.  As a result I never trained for running with the single mindedness that is necessary for peak performance, but in retrospect, I suspect the range of my activities created a fitness base that allowed me to make the most of the limited training that I did.   I have not kept a diary of my running and my memories are sketchy.  I won the South Australian state marathon championship sometime in the late 1960’s.  The only recorded time I have been able to find by internet search is 2:33:07 in the Australian national championships in 1970, but that was far from my best marathon.  As far as I remember my best time was around 2:25.

When training regularly I followed a Lydiard-style training program, though I rarely ran the 100 miles per week recommended by Lydiard.  I mainly skipped the low intensity sessions (the enigmatic ‘1/4 effort’ runs).  Almost all of my training runs were in the mid or upper aerobic zone.  With the self-assurance based on youth and ignorance, I regarded running at any pace less than 6 minutes per mile as a waste of time.  With hind-sight I can see that my various other activities provided the essential base that might otherwise have been achieved by slower running.  I took a sound base level of fitness for granted at the time.


The essential fitness base for distance running

In those days I certainly never troubled myself with the question of what makes up the essential fitness base for distance running.  Distance running depends on many of the body’s systems, including brain, heart, blood vessels, muscles, skeleton, lungs, liver, kidneys and the endocrine system.  While it might be argued that of these brain is the most important, in terms of measurable functions, there are three that are paramount for performance at distances from 10K to the marathon:

1) aerobic capacity;

2) the ability to metabolise lactate;

3) the ability of muscle fibres to withstand repeated eccentric contraction.


Building a base is a long term undertaking

Aerobic capacity is determined by three variables: maximum heart rate, cardiac stroke volume and capacity of muscles to extract oxygen from blood.  Maximum heart rate responds little to training.  Stroke volume increases with increased blood volume, and hence increases rapidly in the early stages of training, but also increases steadily over a period of several years of vigorous exercise.  The ability of muscles to extract oxygen from blood is determined by the density of capillaries, and by mitochondrial enzyme capacity, both of which increase steadily over a period of years.  Thus, training for distance running is a long term undertaking.  To maximise potential, the five year plan is probably more important that the strategy for the current season.


Approaching middle-age

Returning to the account of my own running, prior to re-commencing training regularly a little over two years ago, I had made one previous attempt to get fit.  In 2000, as I approached my mid-fifties, I started running occasionally with the intention of running a marathon six years later, at age 60.  I slowly built up training volume during the period 2000-2002 and in the summer of 2003 introduced occasional interval sessions.  Then after a winter in which I trained only sporadically, I decided at the end of May 2004 that I would enter a marathon in September of that year as a trial run.  I knew I did not have time to get fully fit, but thought it would be a useful trial before my planned ‘serious’ attempt two years later.  I followed a program similar in general outline to that I had followed 35 years previously, but somewhat lower in both intensity and volume.  In the three months from June to August I covered an average of 56 Km per week.  The majority of my runs were in the mid-aerobic zone (around 5 min per Km) together with a few upper aerobic runs.

In mid-August I reviewed progress. I had done several runs of 32 Km without significant DOMS, which I took as evidence that my leg muscles could probably cope with the mechanical trauma of the marathon adequately. However, in mid-August I did an easy 37 Km run with the intention of pushing the pace to about 5 min/km in the final 8Km, and was disappointed to find that I simply did no have the resilience my legs to allow me to increase pace with 8Km to go.  This was perhaps a warning sign, but I assumed that it was due to inadequate carbohydrate loading – in retrospect, I think this was a mis-interpretation – and I concluded it was feasible to press on with my plan to run a marathon in September.

However, as I had not raced for over three decades, I had very little idea of how fast I should run.  In the few remaining weeks there was not time to experiment with potential marathon paced runs.  However, I did have time to assess my aerobic capacity crudely by measuring heart beats per Km in a few medium length runs in the lower and mid-aerobic zone.  Provided one can rule out the confounding effects of stress hormones, circulating toxins arising from muscle damage, and dehydration, beats per Km when running in the lower to mid aerobic zone is determined primarily by cardiac stroke volume and the capacity of muscle to extract oxygen from blood, and can provide a fairly reliable estimate of aerobic capacity.  During three aerobic training runs performed during the taper at the end of August, my recorded beats/ Km were 599, 597 and 581.  These figures indicated that under ideal conditions I could expect to maintain a pace around 4:36 /Km at a heart rate of 130 which was well below my lactate threshold.  Of course I knew that under race circumstances, my heart rate would be higher, but nonetheless, a time in the range 3:15 to 3:20 appeared feasible.

Race day

I was totally unprepared for the melee at the start of the race.  In my previous marathons several decades earlier, the entire field was rarely more than a few hundred competitors, and here I was surrounded by more than 10,000.   In my attempt to break free of the melee, I ran far too fast.  I did not see any mile markers until I reached the third, in something under 21 minutes.   It was clear that I would pay for this misjudgement later, but nonetheless, I settled comfortably into a pace around 4:40 /Km.  I reached 16Km in 71 minutes and the half-way point in 93 minutes, with my heart rate in the low 130’s, confirming my prior estimate of my aerobic capacity.  Predictably, I hit the wall at around 33 Km and struggled with leaden legs to the finish at a pace around 6 min/Km for the final 8 Km, though paradoxically, I was able to mount an impressive sprint in the final few hundred metres.  My time was 3:27:35, which was disappointing but scarcely surprising.  Overall, the evidence indicated that my aerobic capacity was adequate for a time of 3:15 or faster, but my endurance (and pace judgement) was not.



I resumed training with the goal of building up my endurance before a more serious attempt at a marathon two years later.  However I struggled to find time to train adequately (as I often work a 60 hour week), and when my longstanding asthma worsened markedly the following year, I decided to put off my plans to run a marathon again until after I retired.  When I became even  more busy at work in 2005 I stopped training altogether.   About 15 months later, while on holiday I tried to run up a hill and was appalled to find how unfit I had become.  So at the beginning of 2007 I commenced training regularly again, though taking account of my work commitments, I set myself the target of making modest improvements in my half marathon performance, while building a base for later years.

This lengthy story brings us almost up to date, and to the interpretation of my performance while running this weekend.  My long term goal is to build up a fitness base that will allow me to run creditable marathons in my post-retirement years.  Aerobic capacity is one component of the required base, but even more important is building endurance.  In races from 10K to half-marathon, the key element of endurance is the ability to sustain a pace near lactate threshold pace for the duration of the event, and for this the crucial physiological system is probably the biochemical pathway for metabolising lactate.  However, for longer races, the development of resistance to eccentric muscle damage is probably even more important. I am fairly sure that it was eccentric muslce damage rather than either accumulation of lactate or exhaustion of fuel that accounted for me hitting the wall in the marathon in 2004.  It was unlikley to have been lactate accumualtion because my heart rate had been well below lactate threshold.  It is unlikley to have been exhaustion of fuel, because I was able to muster an impressive sprint when the end was in sight.  The most plausible explanation is that my brain surreptitiously applied the brakes on account of circulating toxins arising from muscle breakdown.

Developing resistance to eccentric damage

I suspect that it was resistance to eccentric damage developed through a diverse range of sporting activities in childhood, and extensive hill walking in young adulthood that provided the foundation for my achievements in the marathon forty years ago.  However it is a challenge to know how to re-acquire this in late middle age.  The accumulating fatigue I experience if I attempt to run more than 80 Km per week indicates that increases in training volume must be done cautiously.

How should the build up of training volume be monitored? I have been intrigued to find that heart beats/Km in the lower and mid-aerobic provides not only a fairly reliable estimate of aerobic capacity, provided one avoids the confounds of stress, dehydration and muscle damage, but it might also be used as a index of the degree of accumulating fatigue.

When I recommenced training in 2007, beats/km averaged over three identical aerobic runs in January was 815.  In the past two years, this has steadily decreased and in recent months my average is around 670 beats/Km.  Perhaps by next year I will again achieve recordings below 600, comparable with my recordings in 2004.  But even more interesting is the effect of a long run on the value recorded the following day. I have noted that following runs of 15 Km or more, the recording of beats per Km during an easy run on the following days is always increased, but then returns to baseline after a rest day.  In March, I recorded 697 beats/Km during an easy 21 Km run on a Saturday and 749 beats/Km during an identical run the following day. This weekend, I recorded 665 beats/km on Saturday and 688 beats/Km during an almost identical run on Sunday.  The slightly faster pace in the final few Km would have only accounted for a slight increase in mean heart rate; the difference between the two runs was mainly due to a sustained higher rate throughout.


Over-reaching without over-training

This observation might be regarded as evidence that doing back-to-back long runs is over-reaching, but over-reaching without over-training is the ideal. The return to baseline after a rest day, and the gradual but steady improvement over a period of months, suggests that both my aerobic capacity and my endurance are improving, albeit slowly. I am inclined to think that the evidence for a modest degree of over-reaching after long runs indicates that I am pushing myself hard enough but not too hard, during these runs

6 Responses to “Re-examining the components of base building”

  1. rick Says:

    Downhill running, maybe once every 2 weeks with strengthen your leg muscles for the pounding of a marathon, either run a hilly road route or do downhill repeats, remember to land behind your center of gravity and not reach out and heal strike!
    Working 60 hour weeks is unhealthy, I’d rather be poor and enjoy my life!

  2. canute1 Says:

    Rick, Thanks for your advice regarding downhill repeats. With regard to the long hours of work, I am lucky to have a job that I really enjoy, though as the years go by, I am finding it increasingly hard to keep up with the long hours it demands. I certainly wouldn’t do these hours just for the money

  3. Ewen Says:

    Thanks Canute for a very interesting summary of your running career.

    I think the back-to-back longish runs could be an excellent method to develop resistance to eccentric muscle damage. I know one of Canberra (and Australia’s) best female ultra runners (60 years old) uses this method of preparation – typically 30k + 20k, or 20k + 25k – that sort of thing. I suspect there would also be some glycogen depletion for the second run which would have the benefit of stimulating the use of fat as fuel.

    I like the beats/km (RS scale) method of judging aerobic endurance. I know stroke volume can be improved with specific training – maybe that improves the beats/km additionally to years of aerobic “base” building. I can’t recall where I read about it, but I think the sessions were repeats of short sprints of around 200-300m where the HR is accelerated quickly from ‘rest’ to near maximum. I think it was the fast acceleration of the HR that improved the stroke volume. Correct me if I’m wrong!

  4. Thomas Says:

    Personally I like doing a few strides if the legs feel sluggish early on in a run. It seems to be a good way to put some zip into them.

    I guess the very long back-to-back runs ultra runners do to build their endurance are proof that this kind of training works.

  5. rick Says:

    Its cool you enjoy your job, I think of my 36 hours a week as a life sentence!!!
    Lydiards training gives you a double whammy of tempo run Sat and hilly long run Sun with very fast downhill to finish [ if you run his infamous 22 mile loop] guaranteed to develop your muscles to withstand the pounding of a marathon!!!

  6. Helen Says:

    That was really interesting. Thankyou.

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