QUESTION FROM ATHLETE:
I’ve noticed lately—with the exception of track work, which I’ve been rattling off just fine and have been happy with my performance—that longer runs feel like a slog.  It isn’t an issue of being unable to get HR up, which I understand is a symptom of overtraining, but rather (1) running way slower at the same high HR, and (2) being unable to run at those high HRs anymore.  Today on the hills I had to stop and walk at the top of hills, on a course I normally devour without stopping.

So I guess my question is ... is this normal?  A sign I’m doing “too much” Z2 running and not enough tempo and threshold (i.e. I’ve lost my ability to mentally endure high HR running)?  Cumulative fatigue?  All the cycling?  The heat, humidity, and dew point associated with Texas summer?  Just kind of curious on your take and whether you’ve had athletes have similar experiences. Thanks for not only the coaching but educating me along the way!

REPLY FROM COACH DAVE:
It's definitely good to get this feedback and keep an eye on things.  I think it's totally normal, but we should always be tracking.  You are finishing up a big training block and fatigue is normal--in fact, it's expected.  The "problem" with structured training like we're doing is that it's hard to directly compare any two workouts.  You can't hold everything constant (nor would you want to) such that you could just pick two workouts and compare to see progress.  When we do testing blocks, you've probably noticed that they're identical--I have only created one testing block that I use every time.  The goal is to create the same conditions each time.  Of course, that doesn't actually happen--think of all the other variables besides your workouts: sleep, nutrition, hydration, professional workload/stress, family load/stress, caffeine consumption, general health, heat/cold, humidity, wind, wear on your bike chain...it's endless and gets into tiny details.  So we do the best we can when we test but there's always some wiggle room.  Fortunately, there's wiggle room baked into the training concept.  (Some coaches and athletes think it's straight-up science, but you didn't hire one of those coaches.)  

So when you go to compare last weekend's long run with a long run from last month, they might both be in the same zone for the same number of minutes on the same course, but nothing else is held constant.  The heat and humidity is an enormous factor for a lot of athletes (myself included).  But even small shifts in which way the wind is blowing can make a difference to pace (or effort required to hold a pace).  Obviously, how much fatigue is in your system from the past weeks' workouts play a part.  And then there's that long but incomplete list that I noted above.  This is why looking at pace alone can be deceiving.  Obviously on race day, if we want to work to a specific time goal, we need to pay attention to pace.  But in training, you're going to have "fast" long runs and "slow" long runs--even if both are in Z2, for example.  And running at the same pace is going to feel different on different days.

For IM, you don't need the ability to run at high heart rate--you need to be able to run at a moderate heart rate for a long time.  So you'll definitely lose some of that top-end speed as we progress through the program.  But you are making huge fitness gains along the way that are specific to your goal.  
So on the days when you can't hold a pace/HR combination, there's actually awesome training in that.  You have to "embrace the suffering" and build mental strength to keep moving forward.  It's okay to stop and walk for a bit to catch your breath or reset mentally.  That is outstanding preparation for Ironman racing.  If you can push yourself through on the hard training days (which are not necessarily the longest or most intense days in your training plan), you'll build mechanisms that you can tap into on race day to keep you strong--knowing that you've pushed through worse.

Coach Dave is a USAT Certified Coach and believes that becoming “triathlon literate” is key to meeting your goals. Triathlon is indeed a lifestyle and like the other important areas of your life, knowledge is power. I encourage you to explore the nuances of the sport, be open to new ideas and ask questions – of yourself, of fellow swimmers, cyclists and runners, and of your coach. Whether you’re training to win or new to the sport, the most accomplished athletes are those who are open to coaching, eager to take on new challenges, and are committed to continuous improvement!