The Ideal HR for IM Racing by Coach Mike Ricci From the Mailbag: A question for the first timers, or seasoned Ironman finishers who are familiar with HR zones for first timer: What is the ideal HR zone for the Bike & Run portion of a full IM for someone just hoping to finish? I was thinking it is high Z2 and low Z3. And what is the BPM difference between Bike and Run LT HR zones? Answer: While training for an Ironman race – most of our training should be done in Zone 2 – this is the ‘Endurance Zone’ – and where we can sustain an even heart rate for the longest amount of time. Why? When our heart rate is about 20-30 beats below our Race Pace HR or Lactate Threshold, we are tapping into the biggest resource we have for fuel – fat. When we are above this HR and into Zone 3, we are tapping into more of our glycogen stores for fuel and this supply will not last very long – maybe two to three hours at most before it needs to be restocked. The glycogen is a limited supply of fuel, while fat is limitless. Zone 3 efforts should be reserved for the final miles of a Half Ironman or even a marathon in a well conditioned athlete. But going into Zone 3 in an Ironman for an athlete who is racing for longer than 11 hours, would be a big mistake. When an athlete takes on a new training regimen or has not been training as much, they will experience cardiac drift at first. This is when the effort stays the same, yet the HR rises. I will allow myself to let this happen once per week when I am starting up my training again, but typically I back right down and stay within my HR parameters. Once you have a solid endurance base, you shouldn’t see much in the way of cardiac drift unless you are dehydrated and that is pretty normal. So, stick with the HR guidelines you have when you are starting out and try to avoid Zone 3 when in your early stages of IM training. If you are racing in the heat, you may need to go on RPE and let your HR drift, but only if you start to take on extra fuel b/c you will be burning through your fuel sources quicker. Training our bodies to work efficiently in Zone 2 will help us keep our HR and pace even throughout an Ironman. This theory would hold true for the bike and run portion of an Ironman. When I write a workout and I give an athlete a ‘Zone1-2’ workout, I expect the athlete to find the happy medium and train at a pace they could sustain all day. What I usually get when I check over a log is “..I went out too hard, and well I bonked..” or “..I was much faster on the first hour of my ride and then I kind of faded...” My solution is to do a better job of explaining ‘exactly’ what I want from my athletes. To provide you with a frame of reference, my LTHR (lactate threshold heart rate) on the run is about 160-163. My Zone 1 ends at about 137 bpm (beats per minute). When I run train in a Zone 1-2 workout, and I am running ‘easy’ which is like a ‘guilty pace’, and my HR is around 135 bpm. That would put me about the top of Zone 1. When I am running ‘Steady’ (which I also call my Aerobic Threshold or AeT) I am usually around 140-145 which puts me about the middle of my Zone 2. This would be right about IM effort. After 112 miles, if I can maintain this HR for another 26 miles, I should be able to run the same pace as I do on my long runs, with all things being equal. If you can follow the above and practice the discipline of just running ‘Steady’ when you are assigned those ‘Zone 1-2’ runs, you will improve your running. Spend as much time as you can running ‘Steady’ and it will pay off. Now how does this apply to biking? Once again, to provide you with a frame of reference, my LTHR (lactate threshold heart rate) on the bike is about 155-160. My Zone 1 ends at about 125 bpm (beats per minute). Most of us have about a 8-12 beat difference between bike and run LTs. When I bike train in a Zone 1-2, and I am riding ‘easy’ I am around 125 bpm. That would put me close to the top of my Zone 1. When I am biking ‘Steady’ I am usually around 135-140 which puts me about the middle to the top of my Zone 2. With the exception of climbing hills, I don’t ride over 140 in training. Sometimes I may see 145 on a steep hill, but I quickly get my HR back down by spinning easy. Most of my ‘Steady’ or AeT biking is done at 135-140 bpm. Once again this is my IM pacing effort. Realize that I have to run 26 miles after this 112 mile bike ride, so I won’t punch the accelerator at all if I want to run well. I hope this helps you in your IM quest! Michael Ricci is a USAT Level III certified coach. He can be reached for personal coaching at mike@d3multisport.com. Please visit his website at www.D3multisport.com. Back to D3 Tips