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Development Team Member
Posts: 65
I have two clients I have Moxy tested 5/1/5 that have had excessively high heart rates at the beginning of the tests which come down into steady state about 10 minutes in which is normal.  The funny thing is it only happens in the fall and occurs both outside running and on the treadmill. Both are endurance athletes (Ironmen), both have been training consistently for years, both are experienced users of their monitors AND we have tested this on Garmin and Polar HRM.  They have both experienced HR's in the 180's where normally starting at a low speed it is in the 90's.  SmO2 and tHb trends haven't shown anything abnormal at the beginning of the tests.  Any speculation as to why it would only happen seasonally?  

Development Team Member
Posts: 49
This is a bit of a stab in the dark, but atrial fibrillation is a problem that can appear amongst endurance athletes. I believe it generally shows in athletes who have been involved in endurance sport for many years and is linked in part to the amount of endurance volume they are doing. This article provides some detail. In elite rowing both Rob Waddell and Xeno Mueller, two Olympic champion single scullers have had cases. My understanding is that atrial fibrillation often displays itself as an extremely elevated heart rate. I have no idea what their training volume is like, but perhaps the abnormal heart rate could be linked to the amount of endurance volume they're doing at that point of the year?

Development Team Member
Posts: 65
Thanks NK.  I do have one athlete with an AF diagnosis but it's not these two.  This would be their off-season so on average 6-8 hours of easy a week compared to their 15-18 during competition.  There certainly seems to be more chatter about AF among endurance athletes.  I will re-look at this as a possibility.
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
This  AF is a problem  we know  since many years. The  hindrance  why we not like to talk about is  the fact, that we  may overestimate the benefit  of  extreme   endurnace  sport  when in fact  all extreme version may create  some problems.
  1. S.M. If you have a 5/2/5   assessment sent me the cvs  file as there  are some   very specific places  we may pick up this problem  . I will show later  some   pictures  of    clients  who had  AF   and we  where looking  with Physio flow  and NIRS  what  may happen  and it  does not   show up during load  but in the recovery part.
. Here a   newer  article but there are ample  of articles  to this  part. 

Atrial fibrillation in endurance athletes.


University Hospital, Bern, Switzerland.


There is a growing population of veteran endurance athletes, regularly participating in training and competition. Although the graded benefit of exercise on cardiovascular health and mortality is well established, recent studies have raised concern that prolonged and strenuous endurance exercise may predispose to atrial and ventricular arrhythmias. Atrial fibrillation (AF) and atrial flutter are facilitated by atrial remodelling, atrial ectopy, and an imbalance of the autonomic nervous system. Endurance sports practice has an impact on all of these factors and may therefore act as a promoter of these arrhythmias. In an animal model, long-term intensive exercise training induced fibrosis in both atria and increased susceptibility to AF. While the prevalence of AF is low in young competitive athletes, it increases substantially in the aging athlete, which is possibly associated with an accumulation of lifetime training hours and participation in competitions. A recent meta-analysis revealed a 5-fold increased risk of AF in middle-aged endurance athletes with a striking male predominance. Beside physical activity, height and absolute left atrial size are independent risk factors for lone AF and the stature of men per se may explain part of their higher risk of AF. Furthermore, for a comparable amount of training volume and performance, male non-elite athletes exhibit a higher blood pressure at rest and peak exercise, a more concentric type of left ventricular remodelling, and an altered diastolic function, possibly contributing to a more pronounced atrial remodelling. The sports cardiologist should be aware of the distinctive features of AF in athletes. Therapeutic recommendations should be given in close cooperation with an electrophysiologist. Reduction of training volume is often not desired and drug therapy not well tolerated. An early ablation strategy may be appropriate for some athletes with an impaired physical performance, especially when continuation of competitive activity is intended. This review focuses on the prevalence, risk factors, and mechanisms of AF in endurance athletes, and possible therapeutic options.  

  I had  myself  extreme AF   a  few years back   in connection  with thyroid    reactions.
. I was  schedualed for ablation  but started  to do some remodelling training  of my   right cardiac   ventricle  and I am of   medication  and have  no AF  since  over 5  years now..

 Here another   article  as I have a  " full" library of them  , when I was running into trouble . That's  when I started  to use Physio flow during workouts   to see, how I could influence   stroke volume as well as  LVET  and CCT.
 Hundreds  of hours  of  training   hooked up  to Physio flow  and NIRS  to learn to " manipulate "  blood  flow  and contraction time as well stroke  volume. We  may   look  over the next  few  month  or perhaps years  on here, why we  developped  the idea of physiological testing  ,   instead  of  " performance " testing, as , if healthy  hits  your own   body  you start to think    much more physiologiclaly  than   using  mathematical  forumulas.


Int J Cardiol. 2006 Feb 8;107(1):67-72.


Endurance sports is a risk factor for atrial fibrillation after ablation for atrial flutter.


Heidbüchel H, Anné W, Willems R, Adriaenssens B, Van de Werf F, Ector H.




Department of Cardiology, University Hospital Gasthuisberg, University of Leuven, Herestraat 49, B-3000 Leuven, Belgium.






Sports activity has been associated with the development of atrial arrhythmias. Atrial fibrillation (AF) is frequently observed after successful ablation for atrial flutter. Sports activity as a risk factor for AF development after flutter ablation has not been studied.




We analyzed outcome in 137 patients (83% men) after ablation for isthmus-dependent atrial flutter (excluding patients with concomitant ablation for atrial tachycardia or fibrillation). Sports activity before and after ablation was evaluated by detailed questionnaires. Endurance sports was defined as (semi-)competitive participation in cycling, running or swimming for > or =3 h/week (and for > or =3 years pre-ablation). Median follow-up was 2.5 years. Survival free of AF was evaluated with Kaplan-Meier curves and log-rank statistics. Multivariate analysis was based on Cox proportional hazard evaluation.




Acute ablation success was 99% and flutter recurrence 4.4%. Thirty-one patients (23%) had been regularly engaged in endurance sports before ablation and 19 (14%) continued regular sports activity afterwards. Those performing sports were slightly younger. A history of endurance sports was a significant risk factor for post-ablation AF (univariate HR 1.96 (1.19-3.22), p<0.01, and multivariate HR 1.81 (1.10-2.98), p=0.02). Also continuation of endurance sports activity after ablation showed a trend for increased risk to develop AF despite a relatively small sample size (n=19; multivariate HR 1.68 (0.92-3.06), p=0.08). Cox proportional hazard calculations revealed a 10% and 11% increased risk for AF development per weekly hour sport performed before and after ablation respectively (p<0.01 for both).




A history of endurance sports activity is associated with the development of AF after ablation of atrial flutter.


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Long-term outcome of radiofrequency catheter ablation for typical atrial flutter: risk prediction of recurrent arrhythmias.[J Cardiovasc Electrophysiol. 1998]

Common atrial flutter and atrial fibrillation are not always two stages of the same disease. A long-term follow-up study in patients with atrial flutter treated with cavo-tricuspid isthmus ablation.[J Cardiovasc Med (Hagerstown). 2006]

Studies on the prevalence of complicated atrial arrhythmias, flutter, and fibrillation in patients with reciprocating supraventricular tachycardia before and after successful catheter ablation.[Pacing Clin Electrophysiol. 2001]

Review Typical atrial flutter ablation and the risk of postablation atrial fibrillation.[Ital Heart J. 2005]

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Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Here  perhaps  a  nice one   as we  will hopefully this week look into rowing  and  cross country  testing  with MOXY.
  Cardiac out put  may be limited  in sports  , where we  have   multiple  muscle mass involvement..  MOXY  could be  a potential  early indication  to  control   intensity  in this  sport  to   avoid   using the cardiac  system  always as a compensator.
Eur J Cardiovasc Prev Rehabil. 2010 Feb;17(1):100-5. doi: 10.1097/HJR.0b013e32833226be.

High prevalence of atrial fibrillation in long-term endurance cross-country skiers: echocardiographic findings and possible predictors--a 28-30 years follow-up study.


Department of Cardiac Rehabilitation, Feiringklinikken, Feiring, Norway.



Lone atrial fibrillation (LAF) seems to be more common in endurance-trained male athletes than in men in the general population. The reason for this has not been found.


To determine the prevalence of LAF in long-term endurance cross-country skiers and to examine possible predictors.


Of 149 healthy, long-term trained cross-country skiers from three different age groups who were invited, 122 and 117 participated in the studies in 1976 and 1981, respectively. At follow-up in 2004-2006, 78 men participated, with 33 in age group I (54-62 years), 37 in group II (72-80 years) and eight in group III (87-92 years), whereas 37 individuals had died and seven could not be tracked. The examination programme applied in 1976, 1981 and 2004-2006 consisted of an electrocardiographic monitoring during rest and exercise and a maximal exercise test. Echocardiography was performed in 2004-2006.


A high prevalence (12.8%) of LAF was found. The only predictor from both 1976 and 1981 associated with LAF was a long PQ time (r=0.38, P=0.001 and r=0.27, P=0.02, respectively), whereas bradycardia was another predictor from 1981 (r=0.29, P=0.012). At follow-up, left atrial enlargement was a marker associated with LAF (P<0.001).


Long PQ time, bradycardia and left atrial enlargement seem to be important risk factors for LAF among long-term endurance cross-country skiers.

Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
Here  the pic.  from S.M  case  to  show  you  what we are talking about.

Attached Images
Click image for larger version - Name: SM_AF_1_SmO2_tHb.jpg, Views: 25, Size: 69.48 KB 


Development Team Member
Posts: 49
Hi Juerg,

You mentioned that Atrial Fibrillation could be a negative adaption to a training load placed on an athlete. Would it occur in cases where the heart is compensating for a long time for a limiter somewhere else in the body? Is it related to a specific type of limiter? Or is my thinking from your suggestion way out of whack here?
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
No, you are  again bang on.
 . The   whole  physiological systems   work,  as we discuss here, as a team.
 So  as in any good team  we always have  some limiter  and some , who  on that particular moment  will    jump in and  compensate.
The   question   is  simply   on how long a  compensator  can afford  to   do the additional job   and not  running himself into trouble.
 There  is   basically  in any  physiological system  a main worker  and some  who can    help  and compensate.
 The muscular system  is a beautifully example.
  You have the muscle  chains  as well as the muscle slings. You have  disharmony  in a motion  or you have a  dys- balance in a motion.
  Most  can  recall   an all out 400 m  run in track and field.
  You look great  and loose  the first  100 m.  great hip extension  over the    main  hipextensor  ( glut  maximus ).
  Than     you start to look  okay     between   200  and perhaps 300 m  but  getting somewhat   tight  and than you look ugly    running the last  100 m stretch down.
 You have  minimal  hip extension  the hamstrings  start to jump in to  try to help  which tilts  your pelvic   so you look as  if you start sitting   more than  hip extension. Your glut  medius   will start to try  to do some  hip  extension but messes  up  with   rotational  action  and your legs  start  to move  out     and  ER.
. So  in cases of   technique  your  are really not looking  great.
   and if you train this   ( lactate tolerance )  smile    you very often   destroy   a perfect technique   by  using  compensator's  to    help  for the limitation  of the hipextensor.
  In a more    internal situation.
  Kidney  and respiration.
  balance  of  pH  and   with it    the functioning of the   metabolic  reactions.
    Respiratory   problems   overload  kidney's  and if it keeps going on over many years    respiratory  clients   often  end up with kidney problems.
  If  we stay here  ,  COPD  people  start to overload the  right  cardiac ventricle  and  often end up as  cardiac  patients  , when in fact the problem  was a  respiratory limitation forcing the   cardiac system to compensate.
 In  rowing  we have a   multitude of  reactions.
 1.  Upper and lower body involvement  so   question of    steeling blood  from one body part to  keep  another body part happy. Question,  which one  will win ?
 Compression of the thorax   with compression  on the pulmonary system  as well as on the cardiac system.
. Core stability  muscles  versus abdominal muscles.
  Diaphragm  as the   most important  core   stability muscle.
  So if we get    tired   and the respiratory system  starts  to get into trouble the diaphragm  will loose  its    job  for  core stability  and  you will  start  to  try  to compensate  to move the strength  over legs   through core  to  arms  or vica  verca.
  Who  compensates  for the diaphragm.
    What muscle.  and if  this  muscle groups really starts  to compensate  what    kind of    pressure will it create   on the cardiac system.
. Question of      muscle contraction  and possible  venous occlusion  towards the end of a  race.
  So question of  pre load  due to reduced blood volume return,   so question on  how the  cardiac  system  may try to compensate    due to the lower  preload. ( EF %  LVET  and therefor CCT    higher up  meaning less O2  for the cardiac  muscle itself. ???
 So many  many  interesting questions   . lots' of speculation   very little  answers   ( yet ).

Development Team Member
Posts: 65
So these last points are interesting.  As mentioned earlier this client only experiences these symptoms in the fall when volume is down.  He also experiences muscle tightness and pain in his hips (glute med/pifirormis/QL), hip flexors and triceps surae plus posterior tib that he does not experience in season training and competition.  He has a hard time with circulation to his feet so in season spends a lot of time keeps his calves warm using calf sleeves, hot baths and of course it is a lot warmer outside.  
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
S. M  that sounds  very  interesting and as we see his  Hr  regulated  itself out    with time  ???    blood circulation.
  Pre load ?   SV  , HR  reaction???
 Very interesting and it shows, that sometimes   strange   results  have to be look ed  very carefully  before making and  conclusion.
.  Interesting would be to see, if  we  " warm " up his   lower extremity different let's  say on a bike before a  running test  so no eccentric  , whether his HR   than  does not react  the same  way  or  passive  warming up  with hot  cold      treatment.  Hmmm nature is amazing  and    in some cases  we may have a  strange  diagnosis   creating   out of  a  healthy situation a  sick  person.  (  scary  to think on ideas like that.
 Thee  is a great study  done  I think by  an Alberta  university , where the tested    young health  athletes  out of   the  start phase   and   a  high number  had " arrhythmia  in the EKG  for about  5 - 10 min before  they settled  in.

Development Team Member
Posts: 65
He does not get the same HR reaction when riding the bike outside or on the trainer at anytime of the year.  I will try the pre-warming passively and see if that makes a difference.
Juerg Feldmann

Fortiori Design LLC
Posts: 1,530
hmmm that would  point in the direction  we speculated  above   so now  try  warm up   and than running and see,whether we  do not get  a  HR  reaction as well.
  Eccentric  load   can have   as well some  interesting reactions on HRV . Run up hill    run downhill same  speed  and look the different in HRV   some  have an incredible high HRV  if running downhill.   One of the possible reasons  is the reaction of HRV  due to  very different  breathing pattern. We  can look that as well.   An  other add on.  Do a " VO2  max " test in running downhill and  flat and uphill and  you have  three  different  " VO2  max " values ???
 So m much  for VO2  max :
  If you like to see  why  do the same  with  NIRS MOXY  and you will have three different muscular reaction  trends  with  tHb  as well a SmO2  showing you that this are  three  slightly different activities  with different muscle chain   involvements.  This   can than  help  you     if you like  for example  to train  deoxygenation versus  reoxygenation by  choosing   down  or up hill run  for certain interval ideas. Amotehr  great       use  of MOXY to see, what you are really  doing  in   connection with metabolic   trends  and   blood flow.
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