Cautious optimism

The goal and the strategy

The evidence suggests that my strategy to overcome my recent acute fatigue syndrome with short sessions that include some moderate intensity running might be working.  The goal is to re-train my brain to accept that my body can safely cope with producing at least a moderate power output.  In my post last Monday (31st Aug), I compared the Poincare plot of heart inter-beat intervals recorded during an elliptical staircase session during a mild setback on my path to recovery, with a plot from a similar session in mid-July before the onset of fatigue.  The feature of interest was the extensive spread of points across the 45 degree line on 31st August, indicating excessive input from the parasympathetic nervous system.  This was apparently responsible for the fact that my heart rate could not rise above 143 bpm (averaged over 5 sec intervals), when I increased my power output from 200 to 240 watts.  I had to rely on anaerobic metabolism to generate the increase in power.  This was extremely demanding and in retrospect it was not surprising I found it very difficult to maintain 240 watts for more than a few minutes.  Clearly if I want to be able to produce a moderate power output, it was necessary to teach my non-conscious brain that it could relax the tight control at least a little.

Executing the strategy

During the past week I have done three elliptical sessions and two runs, each relatively short but each including a small amount of moderate intensity activity.  The increase in my heart rate from resting to standing during the orthostatic tests in the mornings has stabilized around 5 bpm – still a rather small increase, but probably within my normal range.  Encouraged by the signs of recovery, I repeated an elliptical staircase session on Friday.  To avoid the risk of stressing my heart too much, I spent only 2 minutes at each level of power output in contrast to 4 minutes at each level on previous occasions.  When I increased my power-out to 240 watts, my pulse rose to 147 bpm.  Although producing this power output required some effort, it was not so crushingly difficult as it had been when my maximum heart rate had been clamped at 143 bpm by my tyrannical parasympathetic nervous system, on 31st August.

Here are the Poincare plots for the three elliptical staircase sessions: mid-July, 31st  August and Friday (4th September).  The plot for Friday’s session is not fully comparable with the other two, because it was recorded after only 27 minutes of exercise, compared with 52 minutes in the other two sessions, and furthermore, the plot is based on a sample of heart beats over 1 minute rather than 2 minutes (because the plots can be misleading during a period of increasing heart rate immediately after an increase in power output).  Nonetheless, the three plots are as comparable as can be achieved in the circumstances.  The crucial point of interest is that the spread of points at right angles to the 45 degree line, which represents parasympathetic activity, is back to a level similar to that in mid-July.  This amount of spread is represented by the quantity, SD1, which was 4 ms  in mid-July; 13.4 ms on 31st August and 3.1 ms on 4th September.   This provides further confirmation that the over-zealous parasympathetic nervous system that had clamped my cardiac output on 31st Aug, forcing me to employ anaerobic metabolism to produce even a moderate power output, had learned by yesterday that it could safely allow the rise in heart rate necessary to generate 240 watts aerobically.

Poincare plots of interbeat intervals in the upper aerobic zone during elliptical sessions before the onset of fatigue (July); during fatigue (August); and during recovery (September)

Poincare plots of interbeat intervals in the upper aerobic zone during elliptical sessions before the onset of fatigue (July); during fatigue (August); and during recovery (September)

It is of course ironic that I am celebrating being able to push my heart rate to 147 in order to achieve a power output of 240 watts.  In June, I was pleased when I managed to produce 240 watts at a heart rate of 141.  However, in June my heart rate increased steadily as power output increased.  As I increased output from 200 to 240 watts, heart rate rose from 132 bpm to 141 bpm – in other words, in June, my relatively low heart rate was not due to clamping by the parasympathetic nervous system, but simply the result of being fitter.  ( It is not surprising that my aerobic fitness has decreased somewhat since early June, due to my illness and the fatigue that developed in its aftermath.  The increase in heart rate at 240 watts from 141 bpm in June to 147 bpm yesterday appears to reflect a decrease of around 4% in my aerobic capacity.  That is not too bad in light of the severity of my illness in June/July.)

A short tempo run

Encouraged by the apparent success of my strategy of short, moderately intense training sessions, yesterday (Saturday) I decided to do a 4Km tempo run.  In my only previous running session this week, I had done an easy 5Km including 4 stride-outs of 200-300m at a pace of around 4:45 /Km.  At the time, it would have required great effort to have increased to a pace any faster than this.  Nonetheless, because of my growing confidence, yesterday I decided to aim for a pace of 4:40 /Km for the 4Km run.

After warming up, I set off running comfortably with a gentle breeze behind me and reached the half-way point in 9:18 (4:39 min/Km) with an average heart rate of 138 bpm.  I anticipated that when I turned into the wind, it would no longer feel like a gentle breeze.  As expected, I had to increase the effort and my heart rate rose rapidly to 145, but I felt fine.  I covered the return journey in 9:20 despite the head-wind, giving a total of 18:38 (4:39.5 /Km).   I arrived home very pleased with my progress.

The next day

However, the crucial question is whether or not today’s orthostatic test would show any evidence of a parasympathetic clampdown indicating over-exertion yesterday.  In fact, this morning the orthostatic difference was 5.4 bpm which is virtually identical to the average value of 5.3 bpm for the entire week.

Thus, at this stage it appears that I am recovering from the excessive parasympathetic activity that had apparently produced the feelings of severe fatigue I had suffered two weeks ago.  Overall the evidence of the past few weeks is consistent with my previous suspicion that my parasympathetic nervous system tends to be over-active.  Furthermore, the evidence of the past week supports the hypothesis that the non-conscious part of the brain that regulates the parasympathetic system can be trained to relax the tightness of its  grip on the control of heart rate.  The question of whether or not I could have achieved the same outcome simply by resting remains unanswered, though the evidence from clinical studies that graded exercise can promote recovery from fatigue inclines me to think that the low volume, moderate intensity program was the right thing to do.


I remain aware that the parasympathetic nervous system serves a crucial protective role and therefore, I must be cautious in trying to modify it.  It is likely that the parasympathetic clampdown and the associated fatigue arose because I had been a little too vigorous in the attempts in early August to regain fitness after my illness in June and July.  Therefore, I will continue carefully, but I am cautiously optimistic.

9 Responses to “Cautious optimism”

  1. Ewen Says:

    That must be a pleasing result – a sign to keep going with the moderate intensity sessions. I remember reading about some research quite some years ago about moderate intensity exercise improving the recovery of athletes with colds and other mild illnesses (recovery was quicker for the exercise group as compared to the total rest group).

    The poincare plot on 4 September is dramatically different to the previous one – the new HRV Polar is producing some interesting results.


    But first, glad to see your making nice progress again.
    Haile Gebrselassie- Lightning bolt and center of gravity.
    It seems every time I read a running magazine coaches and running Guru’s are telling you to land under your center of gravity to reduce braking forces and help you run faster, BUT when I watch slow motion videos of Geb and Bolts- 2 of the fastest athletes at both short and long distance events I notice they land well in front of there COG, do they know something the running Guru’s have missed, or could Bolts and Geb run even faster if they landed closer to their COG?
    Also if you land well in front of your COG but are pulling your foot back to match the speed of the ground- is this no longer over striding?

  3. canute1 Says:

    While it sound sensible to land under the COG to avoid braking, it is in fact impossible to land under the COG and remain upright, at contant speed, unless you spend zero time on stance, in which case ground reaction force would be infinite and your leg would disintegrate.
    When the foot is on the ground behind the COG in late stance, there is a gravitational torque that tends to rotate the body head-forwards and down. When running at constant speed, if this face forward and down torque is not balanced by a torque in the opposite direction applied earlier in the stance phase (ie with the point of foot support ahead of the COG) the body will simply rotate forwards and your will land flat on your face after a few strides. So landing in front of the COG is essential to avoid either a face down crash (or infinite forces and disintegration of your leg).
    Video evidence shows that even Dr Romanov, the proponent of POSE technique, lands in front of his COG (see the PoseTech site), but POSE coaches imply that because full weighting does not occur until midstance, the time on the ground before midstance does not count as landing in front of the COG. I think this is simply wrong.

    Maybe Geb and Bolt could run faster by landing closer to their COG, but they would have to spend less time on stance and this would require greater leg strength to oppose the greater ground reaction forces.


    Thanks for that great reply, After talking to my coach Barry Magee and also Pete mcgill of ‘younger legs’ I’m now coming to the conclusion that a good knee drive is very important in being able to run faster would you agree with this?
    Also what do you think of Dr Yessis’s ideas and book ‘ EXPLOSIVE RUNNING’

  5. Ewen Says:

    Canute, by “in front of C of G”, I take it you mean “behind C of G” when taken from the point of view of the runner looking forward?

  6. dvd vierge Says:

    That’s good to see that you are making such a good recovery.
    You should keep try doing such an practice regularly and I am your that you will be OK in few days.

  7. canute1 Says:

    Rick, I agree that drive from the knee is important, though the so-called extensor paradox indicates that there is relatively little active contraction of the quadriceps at the point of lift off from stance, suggesting that a lot of the power comes from elastic recoil. Therefore I think that plyometric training is likely to increase speed, though I am cautious about the risk of muscle damage from plyometrics , especially in older runners
    I agree with most of the ideas presented by Dr Yessis, though I think that it is necessary to be careful about the mental image invoked during lift-off to avoid risk of over-striding. In general the brain does not send messages invoking single muscle contractions but rather programs full sequences and therefore it is useful to have a mental image of the action of the entire gait cycle. Similarly, I think one needs to be cautious about the image implied by Gordon Pirie’s term ‘bounding.’ I employ a mental image of an elliptical trajectory that carries the foot forwards at lift-off and brings it back relative to the torso (but near to zero velocity relative to ground). I do not focus on actively pushing at lift-off.

  8. canute1 Says:

    Ewen, I meant landing with the point of support (i.e. forefoot) in front of the CoG in the sense of nearer to the finish line and hence in front whether viewed by the runner or by an observer beside the track. This results in a gravitational torque acting in a head back-and-downwards direction during the first part of stance, that is essential to counteract the head forward-and-down gravitational torque generated in the late stage of stance when the point of support is behind the CoG.

    Dvd, thanks for your encouragement. As you will see from my post on 12 September, I think I am now recovered from the fatigue,

  9. Ewen Says:

    Thanks Canute – that’s a clearer description. If the point of support was further from the finish line then the runner would fall on their face – like in the slippery dip video.

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