Archive for November, 2010

A long run in the snow

November 27, 2010

My campaign to get fit enough to race a half marathon by mid-December starting from a fragile base at the end of October, is lurching unsteadily forwards.  After the various misadventures in the early weeks, the problem more recently has simply been too little time to train as a consequence of getting home from work late each evening.  This week, from Monday to Friday, I had not managed a single training run.  When I arrived home last night (Friday), the moon was rising and the stars glittered in a clear cold sky.  I was tempted to go for a run but I felt tired and hungry.  The recording of heart rate variability in the morning had shown that I was quite stressed, so I decided the it would be wiser to eat, relax and then do an easy elliptical session.  The elliptical session confirmed that my decision to defer the run was wise as I struggled even to maintain an adequate cadence for 30 minutes in the low aerobic zone.

This morning the measurement of HRV indicated slight reduction in my level of stress, so I decided that I would do the same HR v power test on the elliptical as I had done last Saturday, to provide a clearer picture of my fitness.  Today my performance was even worse.  Whereas I would normally hope to achieve a power output of 230 watts at a HR of 140, last week my HR at this power output had been 150.  Today it was 152.  That is my worst performance since the period immediately after my recovery from a serious episode of illness in June 2009 when I stopped the test at a power output of 200 watts and a HR of 145.     However last Saturday I had managed a successful progressive longish run despite HRV evidence of moderate stress and poor performance in the elliptical HR v power test.  Therefore I decided once again to do a longish run, my final scheduled longish run before the race in two weeks time.  I had planned to cover a distance of 23-24 Km, including warm-up, a relaxed half marathon in around 2 hours, and cool-down.

Last night’s crisp clear air had disappeared behind a bank of cloud accompanying an almost stationary frontal system that had meandered slowly across Nottinghamshire in the middle of the night  and given us out first snowfall of the winter. The sun rose into a sky that was almost clear again, apart from a some strands of nimbostratus and a few puffy clumps of cumulonimbus.  The ground was covered in a lovely sparkling blanket of snow.  In places where the snow had become compacted the ground was treacherous under-foot, but mostly it was a lovely soft surface, though not a fast surface.

After I had warmed-up and acclimatised to the surface, I settled into a comfortable pace around 5:45 /Km except where it was necessary to slow down for safety’s sake.  A northerly breeze ruffled the surface of the river.  The low-angled sunlight danced off the ruffled water and sparkled from the snow crystals at my feet.  It felt wonderful to be out running.  By 15 Km, I was aware that my legs were becoming a little tired but I found it quite easy to maintain the pace.  Then, in the final 3 Km I increased pace to around 5:10/km and finally to 4:55 for the final Km.  My time for the 21.1 Km HM distance was 121 minutes which was pleasingly near my target.  My pace over the final few Km was a little slower than during last week’s progressive run, but the snowy surface probably accounted for that.  So once again, I was quite pleased with my longish run.

That was the final longish run of my brief campaign.  I have done all six of the intended longish runs and all have gone fairly well.  However, the other parts of my planned program have been rather disastrous.  So far I have done only three of the planned interval sessions and in these sessions I have struggled to maintain a pace much faster that the pace I have achieved at the end of several of my longish runs.  It is clear that attempting interval sessions in the dark when I arrive home tired after a long day at work is simply impractical.  I had planned these sessions, together with some hill repeats, to develop some strength in my type 2A aerobic fast twitch fibres, which have atrophied during my year of disrupted training.  However, in retrospect, this belated effort to develop fast twitch fibres was probably ill-conceived.  At this stage, my greatest needs are to increase by aerobic capacity and speed-endurance.  It would have probably have been more sensible to have included some 6-10 Km tempo runs in the program.  I will do one of two such runs in the next week, but it is now too late to achieve any substantial increase in speed-endurance.

The good news is that the knee that has troubled me since the episode of acute arthritis in February is coping well.  There have been some minor hiccoughs, including the tearing of a few of the fibres that attach my patellar tendon to the tibia, in a spectacular tumble from my bicycle a few weeks ago.   Today my knee was completely trouble-free apart from a very mild ache at the site of attachment of the patellar tendon when I increased pace in the final few Km.    It is also good that I am coping with the HM distance without trouble.  However, I am not yet fit enough to maintain a sustained effort for the entire duration of a half-marathon.  I hope that the tempo runs in the next week will add a little bit more information to help me gauge what might be a realistic target time for the Turkey Trot in mid-December.

Progressive Run

November 20, 2010

My favourite training run is a progressive run – typically a longish run in which I start slowly and increase speed gradually to a pace near the lactate threshold over the final few Km.  I believe this run enhances both endurance and lactate threshold – and most importantly, enhances the mental state in which a sustained pace near threshold when tired is more exhilarating than daunting.

This type of run appears also to be a favourite of Kenyan runners. In his interview with Akio  Harada which I have quoted several times before, Sammy Wanjiru described a typical morning run: ‘Other than that, I run about 15 km at 7:00 or 8:00 in the morning before I have breakfast. I’d say it’s like jogging, or a buildup to something like a pace run. I start around 4 minutes per km, drop it down to 3:30 in the middle, then end up down at about 3 minutes 5 seconds. I always want to finish thinking, “Aaaaah, that felt great. I had a good run.” ‘   Of course I would not consider 4 min/Km to be jogging.  I typically start around 6 min/Km and gradually increase into the upper aerobic zone, perhaps going into the anaerobic zone for the final Km depending on my current goal.  When training for a half marathon I typically aim to achieve a pace a little faster than my estimated half-marathon pace

This week has been a week of mixed fortunes in my campaign to get fit enough to run a half marathon in mid-December, having started from a very fragile base at the end of October.  During my long run of 25.5 Km last Saturday, my heart rate monitor had again recorded a chaotic heart rhythm similar to the recording a year ago that had raised the possibility of atrial fibrillation.   Subsequent investigation has not found any definite evidence.  The structure of my heart assessed by echocardiography, and several clinical ECG recordings, have proven normal.  During the 21 days when I wore a Spider Flash device designed to automatically detect and record any suspicious segments of ECG, there was no trace of significant abnormality.  However, during this period, my Polar monitor did not record any chaotic rhythms either.  However, last Saturday, the chaotic rhythm was back again.  I am still inclined to think that the most likely cause is poor electrode contact, but nonetheless, I decided to take things a little more easily this week, at least until I had established that my heart rhythm had settled.

I did an easy  low aerobic run on Sunday and a low aerobic elliptical session on Monday.  There was no evidence of the chaotic rhythm.  However, I was a little disconcerted to find that my morning measurement of heart rate variability showed diminished high frequency variability suggesting a mild degree of continuing stress.  After another easy elliptical session on Tuesday, HRV on Wednesday suggested I was a little less stressed, so I did a fairly demanding elliptical session on Wednesday evening, and then easy low aerobic elliptical sessions on Thursday and Friday.  I anticipated that by this morning (Saturday) I would be full of vitality.

So I was a little disappointed to wake with an ache in my much-troubled left knee, and a HRV reading that again suggested I was stressed.  I was not sure what to make of this.  Was I over-reaching even with my limited training; was there something else going on?  In an attempt to clarify the situation, I did a heart rate v power test on the elliptical.  In this test, I do a series of 7 x2 minute epochs at gradually increasing intensity spanning the aerobic range.  In the past this has proven to be a good measure of my aerobic fitness.  When I am reasonably fit, at the end of the final 2 minute epoch at 230 watts my HR is usually 140 or lower.  In my fragile state at the end of October, HR was 148 after the 2 minute epoch at 230 watts. Today it was 150 after the 230 watt epoch.  So all the evidence suggested that I was indeed moderately stressed, though I could scarcely believe I was over-reaching after such an easy week.

I had originally planned a progressive 15 Km run starting at 6 min/Km and increasing to 4:45 min/Km in the final few Km.  I decided that I would still set off on my planned progressive run, but if I was finding it effortful, I would ease the pace back to 6 min/Km.

So I set of a little more slowly than 6 min/Km feeling as ungainly as a wombat with a wonky leg.  It was a grey and misty day; most of the leaves are now off the trees and already losing their bright colours as they lie in soggy masses on the damp ground.  However, the still, mist-filled air created a quite enchanting late-autumn atmosphere: a mixture of mellow and crisp sensations.  I felt satisfied in my decision to run, even if I had to limit my pace.   Within the first few Km, I focused on lifting my foot briskly from stance, and carrying my swinging leg through reasonably high, while maintaining a relaxed but rhythmic drive from the shoulder.  By half-way I was starting to feel a little more fluent and my pace was comfortably under 5:30 per km.  I felt more like a wombat pretending to be a gazelle, though I suspect I looked more like a wombat trying to be a kangaroo.

By 10 Km. my pace was 5 min/Km and I felt as if I could maintain that pace indefinitely.   On the long ramp up to Clifton Bridge, the bridge that carries the A52 trunk road high over the Trent,  I eased off the pace a little to avoid too much stress, and I continued cautiously on the down-ramp to avoid upsetting my wonky knee.  However, once over the bridge and with 3 Km to go, I again got back into a good stride.  I covered the final 2 Km in 9:30 min with an average heart rate of 138 (661 b/Km).  When I downloaded the data from my Polar, I was pleased to see that I had covered the final 5Km (including the bridge) in 25:10.   Overall, I felt like echoing Sammy Wanjiru’s exclamation: “Aaaaah, that felt great. I had a good run.”

Maintaining flexibility through active recovery

November 15, 2010

In a comment on my post about six weeks ago, Rick provided a link to an intriguing video recording by Somax.  It raises the critical and controversial issue of the value of flexibility.  Twenty years ago, few athletes questioned the orthodox belief that flexibility was a virtue; stretching was the accepted method of achieving the desired flexibility.  However many studies have undermined the faith in the virtue of flexibility and stretching.  On the other hand, there is good evidence that too much flexibility impairs performance. Relatively stiff muscles like stiff springs, capture and release of elastic energy more efficiently, than floppy muscles. Furthermore, several studies have shown that stretching does not reduce injury.  This evidence has led many athletes and coaches to reject static stretching during warm-up and to propose that such stretching is more beneficial down during cool-down, though there are few studies that provide a clear demonstration that this is the case.

But before addressing this question in greater detail, it is worthwhile to step back and consider the overall credibility of the Somax video.  It has been produced very professionally with informative picture of many elite athletes.  It includes a great deal of thought provoking information about the features of efficient running.  However it also makes sensational statements that appear to me quite misleading.  The video quite rightly points out that getting airborne consumes energy, but claims that runners whose centre of gravity rises 4 inches and falls 4 inches on each step effectively run an extra two miles upward and two miles downwards during a  marathon.  This is a bizarre claim.  It appears to assume that the COG moves horizontally for half the length of each stride and then moves vertically upwards 4 inches, as if tracing out two sides  of a right angle triangle during each half stride.  In fact the COG follows a curved trajectory that is only slightly longer than the shortest possible distance from its low point to its high point on each stride.  The distance travelled by the COG is only marginally longer than the horizontal distance covered.  In fact the COG follows a path that is only about 100m longer than the horizontal distance of the marathon. [Note added 16 Nov: actually the extra distance is nearer to 400m -as described in my reply to the comment by Jan.]

Furthermore, an appreciable fraction of the energy consumed in getting airborne is recovered in the form of re-useable elastic energy at footfall.  In an article presented in the side bar of this page, I describe running as a dance with the devil.  The devil (gravity) does extract a price but we too gain from the bargain. Getting airborne allows us to increase stride length and hence speed, compared with walking at a similar cadence.   The video’s sensational description of the cost of getting airborne makes me wary of other material in the video.  Nonetheless there are some thought provoking claims.   Among these is the claim that increasing passive range of motion at the joints of the leg leads to an increase in speed.

Passive range of motion and distance running

I am very sceptical that passive range of motion is in itself relevant for distance runners.  The normal gait of a distance runner does not involve forcing the joints of the leg near to the limit of their range of passive motion.  In a runner with an apparently restricted short stride, the range of motion achievable during passive movement of the hip by an examiner is usually much greater than the small dynamic range of motion exhibited when running.  There is some evidence that the resistance against passive stretch in the middle of the range of motion is correlated with passive range of motion, and it might be argued that enhancing the range of passive motion by stretching would be expected to decrease resistance to passive stretch in the midrange of motion.  However, I remain to be convinced that decreasing resistance to passive stretch in itself is likely to increase speed.  Many of the important leg muscle actions during running entail eccentric contraction – in which the muscle is passively stretched during active contraction.   Therefore, during running, much of the resistance to free joint motion arises from active contraction of muscles, rather than static inflexibility.

Fibre orientation

However, this is not the whole story.  It is also important to consider the orientation of the fibres that contribute to muscle stiffness.  It is almost certain that the main reason runners develop stiff muscles is that the eccentric contractions that occur during running produce small-scale tearing of the muscle fibres.  This results in a local inflammatory response that promotes the development of fibrous scar tissue.   If these fibres are oriented along the direction of the muscles, they would be expected to do relatively little harm as they would increase the stiffness of the muscle in a way that would increase the muscle’s capacity to minimise damage during eccentric contraction.  However any fibres that are oriented across the line of pull of the muscle will be harmful.  They will create unhelpful resistance to contraction and furthermore might be expected to increase the risk of large-scale tearing of the contracting muscle.

Therefore it would appear very worthwhile to employ strategies to minimise the formation of these cross-bridging fibres during recovery, and to gently disrupt any such fibres that have formed following a previous session, during warm-up for the next run.   It might be that passive stretching can help achieve this, but only if done in a gentle manner that minimises risk of destructive tearing of the muscle.  Above all, the important thing is to apply the stretch in a manner that removes cross-bridging fibres that interfere with the pattern of muscle activity during running.  It therefore seems to me that the one of the most appropriate strategies might simply be performing the action of running, but in a gentle manner.  Thus the most important part of the warm up is simply running itself, starting at a very gentle pace and gradually building up to a pace near to the anticipated training or racing pace.  This of course is what many runners do.

Active recovery

Gentle running during the warm-up might remove the potentially damaging cross-bridging fibres.  What can be done to prevent these fibres forming in the first place?  I think that this is one of the major roles of the recovery run.  The formation of the scar fibres occurs over a time scale of about 24-48 hours after the initial trauma.  It is likely that short-duration easy-paced running during this period will discourage the cross-bridging fibres while perhaps encouraging the formation of fires oriented along the line of pull of the muscle.

As an elderly runner, with reduced resilience in my muscles, I am concerned that even during easy paced running, the eccentric contraction might continue to do damage, so I therefore make sure the recovery runs are very gentle.  Furthermore, because I have access to an elliptical cross trainer, I sometimes substitute a session of the elliptical in place of a recovery run.  When the resistance of the elliptical cross trainer is set to a low level, the leg movements closely mimic the movements of running, but there is no impact and therefore minimal risk of damage from eccentric contraction.  I cannot offer any substantial scientific evidence to support the value of this practice.  However, the fact that during the past few weeks I have been able to increase my long run distance rapidly without any evidence whatsoever of muscle stiffness, and only occasional clunky feelings in my joints, is encouraging.


As I have described several times in recent weeks, I have had a frustrating year due to illness and other misadventures. Between the beginning of May and the end of September, I had trained sporadically and in particular, had done only two longish runs (15 and 16 Km respectively).  In the four weeks from 1st to 28th October I had scarcely run at all.  However, my eagerness to run at least one half-marathon this year led me to send off my entry fee for the Keyworth Turkey Trot, scheduled for December 12th.

So I have set myself the task of getting fit enough to race a half marathon within a month and a half, starting from a rather fragile base.   High on my list of priorities has building up long run distance as quickly as my muscles will allow me.  I have had to jettison the usually rule of increasing consecutive long runs by no more than 10 percent.  However even higher on the priority list is minimising the risk of yet further illness or injury.  I have decided that my best strategy for increasing long run distance rapidly without injury is incorporating a high proportion of sessions devoted to promoting active recovery of my muscles.

In the past few weeks, I have done four longish runs (16 Km, 23 Km, 17 Km and 25.5 Km). I have followed each of these runs with an easy recovery run the next day, and either a yoga session or an elliptical session on the subsequent day.  So far, my muscles have coped without any complaint.

In the remaining few weeks of my preparation I will place increasing emphasis on getting some speed into my legs.  I plan to do two vigorous sessions each week (a progressive longish run of 15-17Km and either a hill session or an interval session) while continuing to include both a gentle recovery run and an elliptical session between any two vigorous sessions.

My total preparation will consist of about 6 longish runs; 6 sessions devoted to development of the aerobic fast twitch fibres that will help me get my pace up to an acceptable half-marathon pace; about 25 active recovery sessions (either very gentle running or elliptical sessions) and a few sessions of yoga and/or strength development.  The yoga sessions will play only a very minor role but will be designed to improve passive flexibility of hip flexors and extensors, quads, hams and calf muscles in addition to promoting physical balance and mental focus.  The strength development will be directed at core, gluteals, hams, quads and calf muscles, with the primary goal of protecting my vulnerable knee.

In this proposed program, active recovery in the form of easy paced running and elliptical sessions will play a much more prominent part than passive stretching because I think it likely that contraction of muscles in a way that mimics as closely as possible the action of running while minimising the trauma of intense running, is likely to be an effective way to minimise the build up of scar tissue orientated across the direction of pull of the muscle.

Overall, I will place greater emphasis on the quality of my recovery than on the quality of my vigorous sessions.  While there is a natural inclination when planning a training program to devote more attention to the quality of the key active sessions than to the quality of recovery, there is little doubt that if I get to the starting line for the Turkey Trot in mid-December in reasonable condition, it will be a greater tribute to the quality of my active recovery sessions than to the quality of the demanding sessions.

Circus of the absurd

November 6, 2010

My planned return to regular training has been dogged by a series of misadventures that started on Monday evening.  I fell heavily when the wheels of my bicycle lost traction on some wet leaves as I descended a steep hill, and my ill-fated left knee bore the brunt of the impact.   The most obvious damage was a skin abrasion from the lower border of the patella to the tibial tuberosity, that prominent bump at the top of shin bone which provides the anchor point for the patellar tendon.  When I examined the damage on arriving home, it was clear that the more serious damage was to deeper tissues.  Exquisite tenderness elicited by pressure applied along the line of attachment of the patellar tendon, together with an accumulating bruise below the tuberosity suggested that I had torn some of the fibres that anchor the tendon to the bone.  However contraction of the quads produced only a slight feeling of tension at the site of attachment of the tendon, so I decided the damage was probably not too serious.

On Tuesday I had a painful knee but otherwise felt reasonably well.  It was clearly sensible to postpone any serious training but I did a Yoga session in the evening.  However Wednesday morning, the measurement of high frequency heart rate variability revealed a value more than two standard deviations below the daily average daily in the preceding week and hence, a value more likely to be a sign of significant stress rather than the result of random fluctuation.   This sign of stress might have been due in part to my unaccustomed long run on the preceding Saturday, but the generalised achiness in my body suggested it was mainly due to the shake-up I had suffered in the fall on Monday.   So I did no training on Wednesday.

Thursday morning the measurement of heart rate variability showed some sign of recovery.   I had originally intended that I would do an interval session, aiming for 3x1000m at approximately 4:30 min/Km that evening.  As I was eager to re-establish a pattern of systematic training I decided that I would attempt the session, though I was very dubious that I could sustain a pace of 4:30 min per Km.

After the delightful weather of recent days, Thursday was quite stormy, with a strong gusty south-westerly wind. As I cycled home from work I felt like a very creaky old-timer, a feeling reinforced when a succession of lycra-clad cyclists sped past me, though I consoled myself that they were all at least three decades younger than I.  It was a further slight consolation to overtake a young woman, at least forty years my junior, who had given up the battle against the wind and got off to walk up the long slow incline towards Clifton; and then a few hundred metres later, I overtook a young man who had also given up the battle with the gusty wind and the incline.

It was long past dark when I got home, but I wanted to run on a grass surface if possible, so I set out for a field about with a perimeter of almost exactly 500m not far from home. As I warmed up, I was doubtful I could even achieve 5 min/Km.  Nonetheless I decided it was best to continue even if the pace was slow.  Although it was quite dark, there was enough light in the sky to allow me to discern quite easily any obstacles the size of a cow.  A slow jog around the edge of the field revealed no fixed obstacles of any size, so I set off at as fast a pace as I could manage.   As I passed a clump of trees I was startled by very loud bang that sounded like the discharge of a shot gun.  The noise reverberated off the more distant line of trees and I wondered who could possibly be out shooting on such a dismal windy night.   Although I could hear no voices nor see any sign of a flash light, I decided it must be some youngsters out hunting for rabbits.  I kept running and hoped that visibility would be good enough to ensure that they did not mistake me for a rabbit.   I completed the first 1000m feeling like a lumbering walrus.  My eyesight was not good enough to allow me to read the time on my watch, despite the backlight, so I had little idea of the pace.  Then, as I passed the same clump of trees on the second 1000m, there was another loud bang that reverberated off the distant line of trees.  I could still see no sign of another human being but I started to become a little worried.  The fact that the two bangs had coincided with my passing of the same clump of trees made me wonder whether it was possible that I was the target.  However commonsense suggested there was no way that anyone could have imagined that there would be a runner of questionable sanity running around that field after dark on such a night, so whatever the intended target, it was not credible that it was me, and I continued with the session.     A few minutes later there was a more distant and different-sounding bang, and the sky was lit by a shower of pink stars released from a sky rocket.  With a sigh of relief and a somewhat sheepish feeling, I realised it was 4th November and tomorrow would be Guy Fawkes night.  So there were probably some kids sniggering to themselves as they ignited a banger each time I passed the clump of trees.

Midway through my third 1000m, I experienced a less puzzling but more somewhat more painful surprise.  To minimise the opposition from the gusty south-westerly, I was following a trajectory that hugged close to the hedgerow along the western edge of the field.  A sudden tearing sensation on my bare right thigh informed me that I was too close, and had snagged my leg on a bramble bush.   The session was degenerating into a circus of the absurd. Nonetheless despite the feeling of wetness that I knew must be blood running down my leg, I finished the session with a feeling of satisfaction.  As I trotted home along the roadside, concentrating on a quick light-footed gait, I no longer felt like a walrus.  I felt relaxed, happy and even perhaps nimble.

When I got home and inspected my legs I realised that any motorist whose headlights had picked me out from the road-side darkness must have wondered what mayhem had occurred.  Not only was there a vivid purple bruise, now tinged with yellow, extending from my left knee over half way down my shin toward the ankle, marking the track of the blood that had seeped subcutaneously from the site of Monday’s damage, but my right thigh was covered by an almost continuous sheet of fresh bright red blood.  However once it had been cleaned-up, it was clear that the spectacular gory mess had been produced by a few minor lacerations of my upper thigh.

When I down-loaded the data from my Polar monitor, I was actually a little disappointed to see that my pace for the three 1000m intervals had been 4:48; 4:48 and 4:47 min/Km.  However, considering how walrus-like I had felt at the beginning, and the various misadventures that had subsequently disrupted the rhythm of my running, I decided that on balance it had been a successful session.

The following morning, yesterday morning, I felt reasonably lively, but the measurement of heart rate variability revealed the lowest value that I have ever recorded while standing in a relaxed posture.  The measurement known as RMSSD was 18.2 ms whereas usually it is in the range 30-90 ms.   It was clear that my aging body was objecting a little to the misadventures that had descended upon my efforts to re-establish regular training, and it was time for another rest day.  However this morning, after a good night’s sleep, RMSSD was back up to a healthy 80.3 ms.  The dawn revealed a cloudless sky, and only a light breeze ruffled the depleted autumn leaves that had managed to cling to the trees through the winds of the previous few days.  I was eager to be out-of-doors, but aware that I should proceed with caution.

I decided on a progressive run, starting at around 6 min/Km and increasing to 5 min/Km aiming for a total distance around 17 Km, depending on how my legs coped.   It was simply a glorious day to be out.  Although the air was noticeably cooler than it had been a week previously, the sun light sparkled off the bright yellow and red leaves, and danced across the surface of the fast-flowing river, swollen with the run-off from the rain that had drenched Derbyshire and Staffordshire in recent days.

Although it was a delight to be running on such a day, the gurgling of the River Trent brought to mind an event that had occurred on the opposite side of the globe around the time that the rain was lashing the Derbyshire peaks on Wednesday night.  I was reminded of the Trent turbo-fan engine, designed and manufactured at the Rolls Royce factory in Derby, about 10 miles upstream from where I was running and named to honour that river, that had disintegrated with a force that blasted a hole in the wing of flight QF32 as it winged its way southwards from Singapore to Sydney.  Fortunately, due perhaps to the expertise of the French engineers who had designed the airframe of the Airbus-A380 and to the skill of the Qantas pilot who brought the plane safely back to Changi airport, all 460 passengers and crew had survived the ordeal.  But I wondered about the implications for the future of Rolls-Royce and its Derbyshire work-force.

But back to today, my knee was holding up well.  I gradually increased pace as planned and covered the 5Km from 12 to 17 Km in 25:50.  Over the final two Km, the effort felt similar to half-marathon effort and my pace was a little faster than 5 min/Km.  Of course my current endurance would not allow me to maintain that pace for the full duration of a half-marathon, but I felt reasonably encouraged by the progress during my first week of almost-regular training, despite the misadventures.