First 1/2 IM coming up in two weeks- depending on August heat, HR may climb out of the aerobic zone to which my plan tells me to stick. Plans says stay aerobic at all costs even to the point of walking. Is this really necessary? Isn’t more about keeping a pace you can maintain for the whole event, or am I going to be really sorry at mile 9 of the run if I don’t stay aerobic to the point of walking?
I can’t answer your question directly, but I can say that if you disregard the heat to maintain pace with an accelerated HR, you will be walking in short order.
Heat will take 30 to 60 seconds per mile off your pace. Walking will take 5 minutes poer mile off your pace. You decide.
XXX,
Is this a training race for you? If it is then you may be better to stick to your plan as going too hard may lead to increased recovery time and a loss of training time for your main race later in the season. However if the HIM is one of your ‘A’ races then do your best get to the finish line as fast as you can!!!
Good luck with whatever you decide
Tommo
Not as sorry as you’ll feel when people pass you while you are walking. Heartrate monitors are great in training, and also for most of your race too. But, this is a race, and sometimes you need to go a little bit outside of your comfort zone. If you’re doing a half, I would hope you’ve done plenty of long runs. If that is the case, toss your heartrate monitor before your run, and go by feel. You might be surprised at what you can do. Just make sure you really focus on your hydration.
Second season of Tris, so Olympic distances have been the norm so far. This is my A race for the year and will be the longest distance to-date. 've trained really hard for this so I know I’m physically ready but am concerned about the heat-induced cardiac drift and whether I should throttle effort back given the heat.
I figured I’d step up one distance at a time and graduate to FIMs next year if each season/distance works out well. Looks like I better get to the end as quickly as I can while making sure I can. Thanks for your input. I really appreciate it.
Should probably watch out for this guy:
.
Hey, this is your FIRST 1/2IM race, unless you have a very strong background in sports, don’t expect to set the world on fire. Enjoy the experience and get one under your belt. NOW to answer your question: If you were an ELITE triathlete, you could expect to slow down in the run from 5-10% under very hot conditions vs ideal running weather. So say you expected to average 8min/mi under ideal conditions, if it’s very hot, expect to do around between 8:24-8:48/mi pace. Now since this is your first 1/2IM, I’d double the slowdown to 8:48-9:36/mi. You can usually see around a 10 beat/min increase in HR at high temps vs ideal temps, for the same pace. If you follow your HR guideline, you’ll automatically get this slowdown. BUT as I said, just get one under your belt if it’s too hot. You have plenty of time to improve on your performance.
This is your first 1/2 IM?
Speaking from experience, the best way not to blow up on the run is to keep yourself under control during the bike. Keeping the pace moderate on the bike may cost 5-10 minutes, but that’s better than keeping those 5-10 minutes on the bike and then losing 1/2 hour on the run cause ya went out too hard.
In short:
Use the HRM on the bike. Ditch it on the run and go for the gusto with whatever you have leftover.
Exactly!! Get rid of that monitor for racing and go off perceived effort and “feel”. Hard to imagine how we ever survived before all these gadgets. Just go for it…it is a race after all.
I’ll tell you what we did before HR monitors. I’ve raced for 35 years, and most of us died at the latter stages of races, because we went by feel and went TOO HARD at the front end of the race. Only the top athletes, after long training and pacing runs, knew how to pace themselves in races. Many of them did even pace or negative split pacing. Us amatures (that’s about 99.9% of us on this chat page, don’t know how to pace ourselves in races, and blow-up in the latter stages. You go by feel if you know exactly what you’re doing, OR you go slow enough so you don’t blow up but than never hit your real potential.
I don’t know the answer to this but does a heat induced increase in HR really mean you’re going “anaerobic”?
It seems to me that if it is hot, your heart is going to be working harder to move blood around your body both it increase cooling and because your blood may be a little thicker due to dehydration. But, that does not mean that the higher heartrate you see is the result of your muscles crying out for more oxygen/fuel which is what happens when your HR climbs solely because of effort level.
I think you need to be looking at more than your HR in this situation to determine your pace and its going to take more than just keeping your HR down by reducing perceived effort to get you through a hot run. Heat will slow you down but not because it takes you out of your aerobic zone.
I am doing my first half on Sunday, August 7. The run will be hot. Here is some advice I am taking to heart:
http://www.byrn.org/gtips/halfpace.htm
Compared to an oly race, I plan to stretch it out and go a bit slower for most of the swim, take it easy for the first hour of the bike and take it easy the first 5 miles of the run. By that I mean while I can charge out at 6:30 miles nearly every time I race an oly, in this race I plan to do 7:30s (and no faster) for the first 5 miles of the run. I have a pretty good idea what those feel like, at least after biking for 2+ hours … I’ll try to throw down some sub-7s if I feel spry later in the run.
I am not going to wear my HRM as I never do in races. To me its a distraction. I am just going to go by feel. I have done a dozen oly races and enough 1/2 IM-focus bricks (30 min. run/2:15 bike/40 min. run) that I feel like I have a decent idea of what pace to go. I’ll find out soon.
HR can vary greatly from training to racing. It’s not uncommon to see a HR 5-10 beats higher for a race than similiar effort in training. Second, high heat and humidity will increase your HR. Your HRM may say your into your LT zone but your running pace may still be an aerobic pace. Will you listen to your body or will you slow and listen to your HRM? Hence learning how you feel at threshold or at long run pace, is as important, if not more, than being a slave to your HRM.
I’d advocate adding in some wiggle room to your HR zones based upon how your recent testing went, temp, humidity, excitement etc. No need to walk b/c your aerobic when your HRM says 5 beats too fast.
Anaerobic is without oxygen. In the heat, most of the blood supply is diverted to the surface (skin) for cooling. This means less blood(oxygen) to the muscles. The muscles are still working hard and need the blood supply(oxygen). With less blood flow to the muscles, the body tells the heart to pump faster in order to supply this oxygen, also because of the heat, the temperature control system in the body tells the heart to pump faster. The cooling sytem and the muscles are in competition for this supply. Who do you think will win out? Cooling has a higher priority in the body than working muscles! Except under very extreme conditions (such as strong mental power, drugs, life & death situation, etc.), the muscles will win out. This is why some people go into heat stroke (a prime example was Simpson the cyclist who died of heat stroke while under the influence of amphatamines). So in answer to your question, yes you’ll go anaerobic.
I guess my point was that if the only “load” on the system is supplying oxygen to the muscles a HR of, say, 155 will not mean the same thing as a HR of 155 if you add a cooling load to the system. If your heart rate goes up (e.g. to 170), you will be able to supply both loads when in theory you are beyond your LT. At some point, you will overload the system just as you can on a cool day but that the overload comes at a higher HR than your “normal” LT HR.
Of course, I’m just winging it 
STP, your question is very good and your reasoning is rational BUT, you also know that when you do the test to determine LT, temperature of your surrounding is not included in the calculation. By the way, if you do include extreme high temperature, LT will actually decrease NOT increase. Your LT calc is a snapshot of your fitness (actually efficiency of the body under performance conditions) at the time taken. Muscle efficiency is directly related to oxygen consumption and LT. As you become more fit, your LT increase to some maximum potential determined by your parents. A few other things that effect HR for the same perceived effort are:. 1. HR drift caused by dehydration 2. HR drop is due to low sugar 3. High HR is due to not recovering properly or illness or heat . This is why racing on HR monitoring alone is not the whole picture. So back to your original inquiry, as the surrounding temperature goes up, your internal temp also goes up to some extent and is dependent on the efficiency of your cooling system. As your internal temperature goes up, the efficiency of your muscles go down. Your LT essentially remains the same unless it is very hot and the muscle efficiency decrease enough to cause a change in your LT.
I’m doing my first HIM on 9/11 in North Texas where it’ll be crazy hot. I’ve recently determine that my sweat rate in hot and humid conditions is an astonishing 5.5 lbs/hr! (I’ve tested this several times.) From experience, I know I can stomach close to 3 lbs/hr, but that still shorts me 2.5 lbs/hr and since I expect to finish in over 6 hrs, I’m worried about dangerous weight loss from water (I’m 185 lbs), and the obvious performance loss associated with it.
Any comments or suggestions?
Hey are you doing Spokane too?
I like to not even wear a watch in some races, just get the surprise when I come up to the line… most times it’s been a pleasant surprise.
WOW, that’s almost 6 pints/hr, you sure that’s right?? In a 1/2IM that is roughly 30 pints for the bike/run portion. To give you some idea, most trained athletes in very hot humid conditions might loose at most 3 or 4 pints/hr and many get by with 2. I’d also be concerned about electrolyte loss. Do you have any cramping symptoms in your training workouts? In fact what have you done during training to counter this sweat loss? Whatever works in training should work race day.
“include extreme high temperature, LT will actually decrease NOT increase”
Hey polarbear, I have noticed my LT decrease in very hot/humid weather, what is actually happening to cause it??