pete75 wrote: ↑25 Jan 2023, 9:56am
Yes, diagnosed in 2014. Didn't know I had it until discovered in a routine blood pressure check
If the electrical activity passes from the atria through the AV node to the ventricles you get tachycardia, known as Fast AF, and you wouldn’t be in any doubt if you had that. Any heart rate over 150bpm is a ticket to resus on the red telephone, and my record HR from the days when I was still un-medicated is 260bpm. If I tried to stand up like that I was on the verge of passing out.
re_cycler wrote: ↑25 Jan 2023, 4:19pmReading through the linked papers there plenty of reference to endurance sport. What I didn't see is a definition to what is considered endurance. In this case should I assume it is defined as an extended time spent at Zone 3 heart rate zone or above ?
There is no standardised definition, because it’s not known. From the ESC Guidelines you posted on the other thread:
“Exercise and atrial fibrillation. The threshold lifetime sports activity for increasing the risk of developing AF is unknown. It is also unknown whether ongoing participation in vigorous exercise at the same intensity after successful AF ablation is associated with a higher risk of AF recurrence.”
There’s a catch-22: it’s difficult to get accurate study results if you can’t separate study & control groups reliably and it’s difficult to separate the groups accurately without knowing the threshold that divides them. If you read some papers about exercise and arrhythmia you’ll see the details of the groups in each one.
Some examples:
2012 Calvo et al: Atrial fibrillation and atrial flutter in athletes.
found 63% of LAF patients who had a history of 3hr/wk of sport for 2yr, compared with just 15% of non-AF controls.
2011 Wilhelm et al: AF and Lifetime Training Hours in Non-elite Athletes
This is a study of 60 non-elite runners stratified according to lifetime training hours (<1500,1500-4500, and >4500). Various biological parameters were measured and compared between groups:
“Signal-averaged P-wave analysis can detect intra-atrial conduction delay and has been used in patients with and without structural heart disease to predict risk of AF”, this was significantly higher in the high activity group.
“square root of mean squared differences of successive normal-to-normal RR intervals (RMSSD) is an accepted measurement of vagal activity in athletes”, this was also significantly higher in the high activity group. Prevalence of AF was found to be 13 times that of a sedentary population.
2009 Mont et al: Endurance sport practice as a risk factor for AF and atrial flutter.
Defines an athlete as >3hr/wk for >10yr, sport increases risk of AF, odds ratio 5.06 to 8.80. Activity increases risk whether recreational or occupational. Results are suggestive of a threshold effect at around 1500 lifetime hours.
2008 Mont: Physical activity, height, and atrial fibrillation.
Conclusion is that accumulated lifetime physical activity (work or play), height, and left atrial size are risk factors for LAF in healthy middle-aged individuals
Moderate exercise:
>6626h increases risk 23 fold,
139-6625h 6.5 fold.
Heavy exercise:
OR=1.8 @ <564h,
OR=7.3 @ >564h. (My lifetime hours are 8300!)
Intensity definitions:
Sedentary: No physical effort.
Light: No increase in heart rate.
Moderate: Light sweating.
Heavy: “Vigorous” (>6 METs)
2008 Molina: Long-term endurance sport increases the incidence of LAF.
Sport is found to be a risk factor for LAF, with a hazard ratio of 8.80. Sedentary is defined as <300kcal/day.
2006 Warburton et al: Review: Health benefits of physical activity.
The fit and active enjoy a 50% reduction in risk of death from any cause. Activity of 1000kcal/wk reduces mortality by 20%. Relative risk of no exercise approaches that of smoking. Effect is graded; small increases in activity also reduce risk. 1600kcal/wk (230kcal/day) is effective at halting coronary artery disease.
2006 Elosua et al: Sport practice and the risk of lone atrial fibrillation.
Current sport practice was associated with a higher prevalence of LAF (OR = 3.13). More than 1500 lifetime hours of sport appears to be the threshold. >1500 h was associated with LAF (OR = 2.87).
re_cycler wrote: ↑25 Jan 2023, 4:19pmThe other thing I couldn't determine was whether as a group the increased risk of atriall fibrillation also came with a decreased risk in other negative medical conditions.
The exercise recommendation for health is 1000 METmins/wk which would be 150mins @ 6.5 METS (~11mph cycling), that’s waaay below what a typical cycling enthusiast is likely to be doing. You can see why it’s been set at that level though, there’s a law of diminishing returns, with little health benefit to be had from doing more:
I was doing about 5-6 times the recommended exercise level.