Another great article

Dave Scott Q & A: How to Avoid Hitting a Wall
By Dave Scott For Active.com
Hitting the Wall on Long Runs
Dave,I'm a long-time runner (12 marathons, one ultra) who has had a problem with fatigue that comes on about 75 to 80 minutes into a long run. It doesn't matter what I do as far as rest before the run, eating or drinking--or even taking walk breaks. I ultimately bonk prematurely for my (presumed) fitness level. My other sub-hour workouts tend to go fine, even if I push the pace.
I've had blood work done that didn't show anything, plus non-traditional testing to see if I had any other medical problems. I've used a heart rate monitor to keep my heart rate under 130 (based on treadmill tests) and that didn't help. I've chased this problem for two years and would like to know if you have any ideas on how to move forward. I love running and would like to do more marathons, but that's out of the question until I get this resolved. Thank you for your time. For the record, I'm a 49-year-old male and have been running for over 20 years. -Kelly
Kelly, are you including one to two sessions per week that elevate your "economy of pacing," which should be faster than your marathon pace? Here's how to do it:
Session No. 1: Include a "swing pace" of one minute. What this means is: If your pace in the marathon is seven minutes per mile, select a run of 40 to 50 minutes (after warm up) that swings the pace from 20 seconds slower to 40 seconds faster (7:20 to 6:20 per mile). Interject this pace fluctuation for an equal amount of time in your session.
Start with a two-minute segment of 7:20 followed by a two-minute segment of 6:20. Repeat this for the 40- to 50-minute block. As your fitness improves, increase the swing to a greater percentage at the 6:20 pace. The advantage of running this session is that it teaches you to burn fuel economically. Conserving muscle glycogen is key to your marathon, and teaching your engine to burn more efficiently is paramount to your success.
Session No. 2: Include either a tempo session equal to five to seven miles at 10 to 15 seconds slower than your 10K pace, or, if this sounds too daunting, select a road or track session of repeats for three to seven minutes (For example: 9 x 100, 7 x 1,200 or 6 x 1 mile). The pace should be hard to very hard.
Here's the key ingredient: keep your recovery between repeats at 15 to 45 seconds. Again, the stimulus for the workout is to increase your muscle strength and fuel economy. And yes, this will help your marathon.
These sessions should be spaced with a two-day window between workouts. Lastly, the first session can be included in your long run. Adding speed will enhance your ability to endure.
Super-slow Resistance Training
Dear Dave, I would appreciate your valuable feedback on the potential benefits of using the super-slow strength training method when training for triathlons.-Phil
Phil, Numerous studies have shown that super-slow training is not advantageous over three sets of six to 12 reps for increasing muscle recruitment and strength. The biggest flaw for triathletes is that they do not include full kinetic chain muscular movements that involve the glutes, back, hips, quads and arms. Even though the exercises (see below) are not triathlon-muscle specific, they will increase the production of growth hormone (GH). GH elevates protein synthesis and increases fat metabolism. The exercises enhance the strength of the entire skeletal system which is important for the triathlete.
My suggestion is to include exercises that enhance the strength of your core, hips, glutes, back, quads and shoulder girdle—the specific exercises (include at least two per session) to elevate GH levels. This is a partial list; I have more exercises on my website, www.davescottinc.com, in the e-programs section under Tri Training.
Squat and curl press with a dumbbell
Leg lifts
Fitball roll-outs with a pike up to a push up
Squat using a bar to over-head press
That's a start,-Dave
When is Enough, Enough?
Dave,I'm a 49-year-old male, married with two boys and 10 years of triathlon under my belt. I'm fortunate. I live a good life, run with one son, swim with the other, do tri relays together. Yet over the past year I just don't seem to recover like I used to. My sleep, mood and outlook have been really altered. I've taken months off (up to three at a time), work with a heart rate monitor, and log everything, yet I get the same results: really bad sleep and quality of life issues. Is it time for an extended break?
Better yet, define an extended break. I've contemplated a year or more off just to see what will happen, but I really do love doing what I do and so do my boys. To stop for that kind of time is a lot to give up without input from a knowledgeable source. What can you impart to me on this subject? -Mark
Mark, your question is a broad one, and certainly your symptoms of poor sleep, mood changes and quality of life issues are complex. Let's take a look at a few areas which will hopefully get you back on track.
To Combat Poor Sleep Patterns
Reduce your caloric intake at dinner and do not have a late night snack within 90 minutes of bedtime.
Take a short nap (20 to 30 minutes) if necessary, but no longer.
Try a short walk (15 to 30 minutes) after dinner.
Don't drink caffeine and limit alcohol to one drink per night.
Use blackout curtains in your bedroom.
Consider using white noise as a means to limit outside noise.
Write down a list of things to do for the next day one to two hours before going to bed.
Don't mentally review work, events, kid stuff, etc. when you put your head on the pillow.
Exercise
Don't stop for three months! Exercise, even for 30 minutes a day, is vital for your immune system, overall health and a good night's sleep.
Exercise elevates the morphine-like chemical endorphins, providing a huge daily jolt of positive energy.
Change your exercise routine: one to two sessions per week. For example, join a Masters swim or running group, join a gym, try a different route for your bike and run sessions. Include three to eight efforts of 45 seconds to three minutes—building in length and frequency—where you are working moderately-hard to hard.
Mental and Emotional Stability
Write down your specific goals every two weeks. Specifically, what pace, heart rate, distance, watts, perceived exertion or simply how you felt during a session. When the goals are well defined without taking the fun out of the exercise sessions, the feelings of accomplishment are much more gratifying.
Look at the goals on a daily basis and revise them every two weeks.
Lastly, we all go through flat spots. Continue with your exercise routine. Try to get in seven to eight hours of sleep and stay ahead of your boys!
Good luck,-Dave