A review of progress

My plan to prepare to run a marathon in 2012 got off to a promising start, but in the past few months I have struggled with ill-health, and it is time for a review.   I had taken up running again in middle age, with the principle goal of getting fit.  But lurking in one of the shallow recesses in my mind was the dream that after I retire from work in 2011, I might train for a marathon.   After three years of fairly regular but mainly low intensity running, I have developed a moderate level of fitness, but I have been a little disconcerted to realize just how difficult it will be to recover even a pale shadow of the fitness of my younger days. By the end of last year, I had run 3 half-marathons, with times ranging from 101 to 103 minutes, and I had enjoyed a few minor triumphs in shorter races, but it is clear that if I am to make any progress against the tide of age-related degeneration, I need to have a systematic plan to deal with some of my weaknesses.

The first issue is that despite running fairly regularly since my early sixties I have been losing muscle strength steadily, and my stride length has shrunken.  In an attempt to deal with this, in the three months from November 2009 to January 2010 I had done a moderate amount of body-weight resistance work.  I achieved a modest improvement in strength. I had increased the distance that I could cover in 5 consecutive hops for 9.01metres to 9.71m in the left and 8.56 m to 9.30 m on the right.  My right leg has been weaker for many years as a result on intermittent attacks of arthritis.  Unfortunately, in January I suffered yet another episode of arthritis.  It started in my neck but eventually spread to my knees though this time it has mainly been the left knee that has been affected.  Although the pain resolved within a few weeks, I have had various other complications that have limited my ability to resume systematic training.

I am still wary of putting too much load on my knees so I will proceed cautiously with leg strengthening for a little while longer.  Meanwhile, my medium term goal is a half marathon in September, aiming for a time under 100 minutes.

Developing aerobic capacity

The paramount requisite for the half marathon is aerobic capacity.   To run a good half marathon, it is necessary to be able to sustain a pace near to the anaerobic threshold with only slight accumulation of lactate for 13.1 miles.   Since the anaerobic threshold is the point at which lactate production increases markedly, production is relatively low below this threshold, but is nonetheless appreciable.  It is essential to develop a good capacity to metabolize lactate.

There is a bewildering array of claims about the best training program for increasing aerobic capacity.  In fact, there is good evidence that quite different types of programs ranging from high volume approaches advocated by Arthur Lydiard or high intensity programs, such as that developed by the Furman Institute can be successful.   While it is encouraging to know that there are several of ways to achieve the goal, the challenge is finding the style of training and amount of training that produces the best result for each individual.  How can we find the sweet spot where training is maximally constructive without becoming destructive?

Looking back

The starting point is examining one’s own history of response to training.  In the days when I ran competitively, I was actually more enthusiastic about mountaineering than running, and it is difficult to disentangle the effects of mountaineering from the effects of my running training.  In those pre-internet days, knowledge about training methods was largely spread by word of mouth.  The local gossip included accounts of Percy Cerutty’s advocacy of running up sandhills, and Lydiard’s advocacy of running 100 miles per week.  I rarely ran up sandhills, but there were a few brief periods when I ran 100 miles a week.  However mostly, rather than waste time on long easy-paced runs, I preferred to spend long days carrying a heavy pack in the mountains.  Most of my running training consisted of runs of 5-10 miles at ‘a good aerobic pace’.

Measuring heart rate while running was not practical for the amateur athlete forty years ago, but I did use my breathing as a guide.  I usually trained somewhere between the point where my breathing became quite noticeable (at a rate around 45 breaths per minutes) and the point at which it became labored and increased to about 90 breaths per minute.   Although terms such as lactate threshold, aerobic threshold and anaerobic threshold were not commonly used in those days, in retrospect I suspect that onset of noticeable breathing at 45 /min probably corresponded approximately to aerobic threshold while laboured breathing at 90 / min was probably a little above anaerobic threshold.  I rarely ran any slower than 6 minute miles in training.  I suspect that in today’s terminology, most of my runs would have been described as tempo runs, though they were rarely demanding.  So in summary, mountaineering provided my base fitness and ‘good aerobic’ tempo runs provided ‘race fitness’.

Because I was not really serious about running, I have not kept any records of my race times. I had a few memorable moments on the track, but I ran track races mainly to earn points for my club in the interclub competition.  I had a slightly more notable career as a marathon runner   I raced four marathons.  I won the South Australian State championships in the late 1960’s; I subsequently represented South Australia in a reasonably creditable manner at the Australian national championships; I didn’t finish on another occasion due to an asthma attack precipitated by a chest infection; and I contributed to my college team’s third place in the PolyTechnic Harriers marathon in London in the early 70’s.   My fastest time was around 2:25, in the Poly.

I will never know whether or not I might have done better if I had devoted myself more single-mindedly to running, but I suspect that my training suited my natural physiology quite well.   Perhaps due to genes, or to running to and from school as a youngster, or a combination of both, I am fairly certain that I have a predominance of slow twitch fibres.    According to Dudleys famous studies of rats running on a treadmill (Journal of Applied Physiology, 53; 844-850; 1982)  the most effective way to improve the aerobic capacity of slow twitch fibres is  to run in the upper aerobic zone for about 60 minutes per day, 5 days per week.  I suspect my frequent 5-10 mile ‘good aerobic’ tempo runs were not far short of perfect for maximizing my aerobic capacity, and my treks in the mountains  provided the necessary base fitness.  I am also intrigued to note that Marius Bakken reports that his observations during his time in Kenya indicated that Kenyans do a lot of their training just below the lactate threshold. http://www.mariusbakken.com

The current situation

Unfortunately, now I am in my mid-sixties I do not recover quickly enough to do frequent ‘good aerobic’ tempo runs.  Even more unfortunately, I now rarely have the time to spend long days in the mountains.    Nonetheless, without specifically planning it, my recent training has followed a pattern that bears some resemblance to the training of my younger days, though greatly reduced in both volume and speed.  The long days in the mountains have been replaced by fairly regular longish (15-20KM) easy paced runs.  The majority of my ‘faster’ runs are 8-10Km ‘good aerobic’ tempo runs or progressive runs in which I start slowly and work up to a good aerobic pace for the final few Km.  I also do some tempo style sessions on the elliptical cross-trainer and occasional interval sessions.

Although the most recent of the three half-marathons that I have run in the past few years was the slowest on account of a quite debilitating illness lasting a few weeks about 2 months before the event, it was the most informative about my current physiological status because I was able to record times and heart rate for 1 mile splits using my relatively recently acquired heart rate monitor.

In light of my inadequate preparation due to the recent illness, I had started that race with the intention of maintaining approximately 8 min/mile to the half-way point and then if I was coping, increasing the pace in the second half.  The first half went well and I reached 6 miles in 47:10 (7:52 min/mile) according to plan.  I picked up pace in the seventh mile (7:22 min), but then a minor disaster struck – I tore a hip adductor muscle while turning abruptly. I was forced to limp awkwardly and it was clear that unless I could find some way of protecting the adductor, I would have to drop-out.  I spent the eighth mile experimenting and found that a shuffling gait with short strides and minimal airborne time alleviated the pain in the adductor.  Provided I increased cadence, I could achieve a reasonable pace.    By 9 miles I shuffling along at a pace faster than 8 min/mile, and managed an average of 7:55 /mile over the final 4 miles.  As I described in my blog posting a few days after the event, I threw caution to the winds and raced the final 200 metres – tearing a few more fibres in adductor but none the less, pleased that I had rediscovered a little bit of the fighting spirit of my younger days.

The Heart Rate Monitor revealed that my average HR over the entire race was 137 (87%  of my estimated maximum HR).  Most importantly, the monitor indicated that I had maintained this rate with very little drift.  For miles 2 to 6 I maintained a pace of 7:53 /mile and average HR of 137 ( 675 beats/Km).  Despite shuffling in an ungainly manner for miles 10-13,  I achieved a pace of 7:55 /mile, and average HR 139 (681 beats/Km).  In view of the inefficiency of the shuffle, the rise in beats/Km compared with miles 2-6 was trivial and suggests that I was capable of maintaining 87% of maxHR  for 13.1 miles without appreciable upward drift.

While I would expect a well trained runner to maintain a HR around 90% of maximum with minimal drift during a HM, I am pleased that my relatively low volume of training had got me to the level where I could maintain 87% of HRmax without appreciable drift.   It is perhaps reasonable to expect that with a modest increase in training volume, I could develop my endurance to the point where I can maintain 89 -90% of HRmax for 13.1 miles.   Thus I can expect to reduce my time by a few minutes, perhaps down to 100 minutes, simply by increasing endurance.  I am fairly confident that an increase in training volume will achieve this.

If I am to make any greater gains, I will have to increase my aerobic capacity.  In my experience, beats/Km when running in the aerobic zone over flat terrain provides a fairly reliable proxy estimate of aerobic capacity.  At first sight, my recorded values of 675 b/Km from 2-6miles and 681 b/Km  for miles 10-13 in the half-marathon appear creditable– especially as the RH half-marathon is run on a hilly course.  In fact these figures for beats/Km would probably match those of many sub-elite runners.  But there’s the rub.  These figures suggest to me that there is not a great deal of scope for further improvement in the aerobic capacity my slow twitch fibres.  Recent experience indicates that I might achieve around 620 b/km, but I suspect that it will be difficult to improve much further than that.  If I can maintain HR 140 b/min for 13.1 miles and it costs me 620b/Km, my half marathon time would be 93 minutes.

Of course if I can achieve 93 minutes within the next two years I will be extremely pleased with myself; in fact if I can get below 100 minutes this year I will feel quite content.  However the interesting question is whether or not 93 minutes for a half-marathon would be my absolute limit.  And if so, why is this so much slower than I was capable of 40 years ago?  Although I never raced a half marathon in my younger days, my marathon performances suggest I was probably capable of running a half marathon in about 70 minutes.

The immediate answer is that I am now limited by my maximum heart rate.  With a HRmax of 157, I cannot expect to maintain greater than an average of 140 b/min during a half marathon.  Even if I can increase aerobic capacity to achieve 620 b/km, my pace will be limited to 4:26 min/km.   HRmax generally declines with age and it is widely believed that it is not possible to increase HRmax by training.  My own experience confirms that aerobic training does not increase HR max.  In fact the greater my aerobic fitness, the harder I find it to achieve near-maximal heart rates.    However, in light of the observation that my muscle power has decreased markedly as I have aged, I wonder how much of the decrease in HRmax and my apparently creditable low ‘beats/Km’ during aerobic running can be attributed to the fact that I no longer have an adequate mass of muscle to recruit.

Speculation 

This leads to a somewhat speculative conclusion.  First of all, past experience suggests that with a moderate increase in training volume, especially with an increase in the number of ‘good aerobic’ tempo runs, I can get my type 1 (slow twitch) fibres into peak condition.  Because fortune appears to have blessed me with a fairly high proportion of type 1 fibres, I have a reasonable chance of running a creditable half marathon (and after another year or two of training, perhaps a similarly creditable marathon).  However I will be limited by my deteriorating muscle mass.  If I want to push back the limit, I need to increase muscle mass.  In practice, this means increasing type 2A (fast twitch aerobic fibres).

These considerations suggests that while having a high proportion of type 1 fibres provides a sound  foundation for running a fairly good marathon, to reach one’s peak potential, it is also necessary to have at least moderately well developed type 2A fibres.  So while my primary goal over the next few months is increasing the oxidative capacity of my type 1 fibres, I will also return to the challenge of building up type 2A fibres.

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3 Responses to “A review of progress”

  1. heart pulse monitor Heart rate & lactic acid buildup? Says:

    […] A review of progress « Canute’s Efficient Running Site […]

  2. Ewen Says:

    Canute, 93 minutes looks to me like a good HM goal, and a good test to see if you can get the training balance exactly right. I’d say there’s a lot to be gained by increasing muscle strength and ‘spring’. Force off the ground (that we all have when young, as well as higher max HRs) would seem to be a ‘free ride’. I’m thinking that if the muscles are strong/springy we can produce a longer stride for the same aerobic cost (beats/km).

    The one thing that has me pondering how good aerobic conditioning can become are the training regimes of elite older athletes like Hosaka (210k per week) and Ed Whitlock (3 hours daily of ‘jogging’).

  3. canute1 Says:

    Ewen,
    Thanks for your comment. Ed Whitlock (and also Robert Cheruiyot, who achieved a 2:06 marathon with a weekly training volume of 280 km largely made up of one hour runs at a pace about 1.5 min/mile slower than his marathon pace) provide clear evidence that large volume, low intensity training works. It is not clear to me what physiological change the long slow runs achieve, in light of Dudley’s studies of rats, which suggest there is little further increase in oxidative capacity of type 1 fibres (assessed by measuring cytochrome oxidase ) after 30-40 minutes of low intensity running. Very long runs might be expected to increase capacity to store glycogen and also to metabolise fats – but that doesn’t account for Whitlock’s achievement over shorter distances; not for Cheruiyot’s marathon achievements based largely on 90 min slow runs. It would seem logical to assume that once the type 1 fibres are exhausted, the type 2A fibres are recruited, but Dudley’s data do not provide much evidence for that. Maybe Dudley did not keep his rats running for long enough at low intensities to fully exhaust the type 1 fibres – or maybe humans are different from rats. However it is also noteworthy that Ed Whitlock built up his training mileage over several decades and perhaps that was the crucial factor – one might expect steady increase in capillaries over many years.

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