11/1/15 6:53 PM

the VN article about Zinn's problems and <a href="http://www.cyclingforum.com/phpBB2/viewtopic.php?t=11391">this forum thread</a> got me thinking.

is there something specific to the physiological demands of competitive cycling, the incredibly spikey nature of the power/HR in particular, that makes cycling more likely to cause arrythmia in older cyclist compared to say running or speed-skating xc-skiing or any one of a number of other endurance sports? the other sports can be similarly demanding, but the HR demands are generally pretty smooth.

in bike racing HR traces are all over the freakin' map. well mine are. one second i'm noodling along barely above 100 and the next moment my HR is knocking at 190.

anyway, just curious if there's a sport-specific dimension to this.

11/1/15 10:54 PM

The first study that I came across a few years ago was a study on Finnish Elite cross country skiers and 20% of them developed AFib. The demands of XC skiing are not that different then cycling as most courses have a good amount of altitude change. I still skate ski and the HR is pretty high when climbing and of course quite low when going down the other side similar to cycling. I think running (non-trail) and speed skating would have a more constant heart rate. There may be something to this as I have not seen as much about AFib and running as I have about cycling and XC skiing but I have no data to back this up.

11/2/15 1:14 PM

I think cyclist tend to go much harder when they go hard compared to runners. I think the average HR is higher for running (shorter efforts and very steady).

Running just can't hit the peaks that cycling can because their is much less anaerobic effort in cycling.

11/2/15 1:52 PM

Maybe not just the same, but I think longterm runners have cardiac concerns as well. I recalled the runner/author Jim Fixx who died suddenly of a heart attack, and a minute of googling yielded, FWIW:

http://www.runnersworld.com/newswire/heart-risk-marathoners-have-larger-plaques-in-arteries

11/3/15 6:08 PM

OK CTS study of its coached athletes found no correllation to cycling. Maybe the presence of A Fib in general population also carries over into cyclists etc.

Myself I have a bundle branch block from excercise related left ventricular hypertrophy but aside from the timing of the chamber firing being slightly delayed, have absolutely no symptoms. I am 56 and have been racing competitively since age 13 (never at any level lower than cat 2 on road or track since leaving the junior ranks). I can still spike my heartrate into the 230 range with a 1400 watt =/- effort but no afib. Back to normal operating range within 90 seconds. I tend to race with heartrate in the 130s to 140s and a bit higher when making a hard effort.

After all this time, I do not characterize masters racing as an "endurance" sport, rather as a "speed/power " sport, more like power lifting. While I occassionally ride senior crits of 50 miles or 100K, these tend to be my longest rides. The longest Masters races I do tend to be around an hour, with under 30 minutes being typical.

From October to December I ride steady an hour or so a day and try to get 20 days a month on the bike. December through early April, I throw in a Computrainer interval workout of around an hour once or twice a week (after I'm done, I can hardly walk and am shot for 72 hours). Late April through Early October I just race and recover. This last season for example, I rode 57 races, missed three weeks in mid-June due to viral illness, and won 8 of those events. 7 Masters, 1 senior men. 3 road races, 2 time trials, 2 track races, and 1 crit. I plan to race about 70 times next season.

11/5/15 8:28 AM

attention from the more mainstream media:
http://www.wsj.com/articles/the-potential-cardiac-dangers-of-extreme-exercise-1446681536

11/5/15 9:34 PM

quote:

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I can still spike my heartrate into the 230 range with a 1400 watt =/- effort but no afib. Back to normal operating range within 90 seconds.

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