Need some advise on the causes and prevention measure of a strange phenomenon that I experienced during a 70.3 race over the weekend.
The swim and first 70% of the bike route well as planned. My hydration and nutrition plan that I had experimented over the last 3 months of training was on track. But towards the last one third of the bike leg, my HR dropped from my normal race pace of 88-90% to about 80-82%. My muscular performance dropped as well where my average speed dropped from about 19MPH to about 16MPH. No matter how hard I tried to get my HR up to race pace, the HR just stayed at about 80%, even during a climb. I tried increasing/decreasing cadance, increase my perceived effort, but it did not help at all. I’m quite sure it was not an HRM indication error. the low HR problem continued throughout the run. Naturally, my run performance was not as good as I had expected, but I still managed to finish the race with some improvement to my last year’s 70.3 timing (this is my 2nd 70.3). I felt fine throughout and after the race except that I could not increase my low HR no matter how hard I tried. This is the first time I’m encountering this.
Can anyone advise what’s the cause for this? What are the prevention measures from a re-occurrance? Any reason to be concerned as far as cardiac health is concerned?
Have you checked your resting HR to see if it is elevated. Over training can cause
a lowered HR as well as elevated. Has your training been at the level your used to
and if so were you ready for that level.
Just a thought
Mike
My resting HR was normal on race day morning and I had settled on a routine training prog for the last 3 months. Although I must admit that the tapering could have been more. Other than that everything looked normal before the race.
Not trying to be rude about this, but are you “sure” your nutrition was the way it should have been? Because given the timeframe that you would have been at on the 3rd lap of a 1/2IM course, this is pointing to not enough fuel in the tank.
This also sounds like too aggressive of a pace- is the 88-90% based on threshold values, max/peak, or something else?
Personally, sounds like a nutrition, and specifically, an electrolyte issue. I’ve experienced the same thing and found that it was a lack of Na+ and K+ (Sodium/Potassium) that caused it for me. Your body needs the electrolytes to transfer the trigger signal to both your skeletal muscles and your heart. Without them, signals are decreased and rate of fire is decreased (and inconsistent ie. Cramps). It not only has an effect on cramping and strength, but on cardiac function as well.
Was it particularly hot, or did you sweat more than normal and were you taking adequate sodium/potassium supplements? Potassium always seems to be the one that gets me. I make sure to supplement before any hard workout or race, and then take in plenty of sports drink and endurolytes during the event. It is next to impossible to take in as much sodium/potassium as you are losing on a hot day.
Thanks for the feedback. I suspected it might be a nutrition and electrolyte issue as well.
The race was in Singapore so it was relatively hot and humid, but I live and train here so I should be used to the condition. Incidentally, race day was rather cloudy and cool so the race condition was actually better than what I was used to during training.
During my weekly long brick training (90km bike + 10km run) over the last 2 months before the race, my hourly nutrition plan consisted of 2 powerbar gel (about 200KCAL) and 750ml (about 26oz) of water spiked with 1.5 NUNN electrolyte tablets. So over the 4 hour session, I would consume a total of 8 packs of gel and about 4 bottles of water spiked with 6 NUNN electrolyte tablets. I could usually maintain a good bike/run pace and HR of about 88-89% for the 4hour or so. The only difference during race day was the swim effort which I had not factor in during my training… Looks like I’ll have to plan out a more robust training program and nutrition plan for my next race…