Logged another long run with hill intervals today, increasing the pace from 10:00 to 9:30 but staying with the 5% incline. The faster pace appears to have resulted in a 5-8 point increase in HR during the steady state portion of the run, ending up at around 145 compared with around 139. This is the longest run on this cycle
One of the reasons I like using the heart rate monitor and data recorder is to get a quantitative view of how training is going. The hill interval portion of the graph is more interesting to look at. Part of what I’m after at the moment is to get a better sense of what my current LT (lactate threshold) pace is.
One of the objectives for longer interval training is to improve the body’s ability to function in the presence of lactate. The higher level of effort raises the body’s energy demand beyond what can be generated through primarily aerobic metabolism, and the anaerobic systems become more important. The body’s aerobic energy systems are much more efficient than the anaerobic systems, but have a limited rate of energy release. Training for endurance sports, such as marathons or triathlons, focus on developing the body’s cardiovascular system to increase its aerobic capacity, and also on increasing the lactate threshold, which allows sustained physical effort at a higher, partially anaerobic level.
During incline or pace intervals, you’re moving the body’s energy production in and out of mostly aerobic and mostly anaerobic modes. It is important to select levels of effort that allow recovery to an aerobic effort and also pushes into the anerobic range, but without requiring one to stop. If you simply continued at an anaerobic level of effort, you’d have to stop fairly soon, but an interval workout allows you to spend more time training at a useful level of effort. The first few intervals typically feel easier than the last ones, but the goal is to find the level of effort is difficult but can be maintained. I usually try to do at least 3 repetitions.
The adaptation we’re after is an improvement in the body’s ability to buffer lactic acid. This increases the sustainable level of energy output for longer distances. If you spend too much time too anaerobic during an endurance event, you typically exhaust the readily available glycogen (”hitting the wall”, “bonking”) which is unpleasant and dramatically reduces the energy available to skeletal muscles. The LT pace corresponds to a level of effort that is faster than comfortable, can be sustained for an extended period of time (an hour or more), and if exceeded, would quickly require that you slow down to recover from O2 debt.
Part of my current planning challenge for this year’s Big Sur Marathon is that my physiological performance is very different (worse) than where it’s been over the past few years, so I don’t have a good sense of what my sustainable paces actually are. I also don’t have a clear sense of the root cause, other than some test data showing that my breathing is slightly off.
Based on today’s data, it also looks like I can hold 9:30 pace without any problems for two hours. The HR graph isn’t trending up, either, so I may already be able to manage 9:00 pace for two hours, especially if I’m not starting off with hills.
On this training cycle, so far I’m not having any sore muscles. All of my training issues (other than not breathing well) have been with mental fatigue and elevated HR. At my current level of O2 intake, I don’t think I’m pushing the muscles very hard. We’ll see what happens with longer runs and faster paces. Although allergy season is starting, I think the medication is helping more than the allergies are hurting.
Tags:
fitness,
hrm,
marathons,
running,
training
