This article was originally posted by Ryan at the original HillRunner.com Blogs.

I think I sometimes drive the runners I coach crazy talking about efforts. Easy, 10K effort, 5K effort, half marathon effort. These are common phrases in discussions.

Just this past week, I’ve had discussions with three runners I coach on what exactly these efforts mean and/or why I prefer training by effort over other methods, such as pace. I may explore this topic further in a future post but I’d like to share some high level thoughts on a few key points that I believe make training by effort the best way to train.

1) Training by effort helps you learn the correct effort to run a race at. You’re going to make a few mistakes when learning a new skill like running by effort. Would you rather make those mistakes and learn from them in a workout or in a race? Why is this skill important in racing? Read on…

2) Training and racing by effort allows you to adjust for variables on the fly. Once you’ve honed your skill to run by effort, you will naturally adjust for things like adverse (or more ideal than expected) weather conditions, course related factors such as hills or even factors such as the lack of sleep you got last night or the stress of a bad day at work. Running simply by pace won’t account for these factors and will leave you running a less than optimal pace/effort level. Running by heart rate may help you with some of these factors but it won’t do much when your legs are fatigued because you helped your friend move yesterday. Also, your heart rate doesn’t always respond to all stresses in an expected way and doesn’t always respond to your effort level instantly. If you fine tune your ability to feel your effort, you can know instantly when your effort level changes. Relying on heart rate may leave a delayed response. You’ll find out before disaster strikes but will you find out in time to adjust for an optimal performance?

3) Running by effort ensures you’re doing the workout you intend to do. When trying to stimulate a physiological response from our training, we need to hit a certain effort level. Depending on some of the factors mentioned above (weather, course factors, life factors leading to more or less stress than usual) a given pace may be too fast or too slow to best target the training stimulus we want to focus on. If you’re doing a workout that should target 5K pace/effort but you take the workout to the hills, you have to back off your pace. How much? Every hill is different. It’s hard to tell without going by effort.

4) Running by effort removes your succeptibility to technological glitches. Just last week, I had a run where my Garmin flaked out. It had me starting far from where I actually did start and reported a first mile of 3:31. No problem. I wasn’t relying on it so I just ignored it and figured it was just a stopwatch for that run. What if I was relying on it to set my pace? Would I have been lost until it locked into my location? What if this happened on race day and I was relying on it to set my race pace?

This article was originally posted by Ryan at the original HillRunner.com Blogs.

Writing about another study (I promise this blog won’t become all about reviewing studies but this will be a part of it). This time, a study of how weight loss as a proxy for dehydration and myoglobinuria as a proxy for muscle breakdown are related to reduction in muscle power. Essentially, the idea of this study is to determine what the correlation is between late race muscle fatigue and two commonly held explanations for that muscle fatigue.

In a break from commonly held assumptions, body mass loss (the proxy for dehydration) did not seem to affect muscle power output. Participants in the study ranged from gaining body mass to losing more than 4% of body mass (that would be 6 pounds for a 150 pound person) during a marathon but loss of power output was not correlated with body mass loss.

On the other hand, there is a quite strong correlation between myoglobinuria production (the proxy for muscle breakdown) and muscle fatigue.

What does this tell us? Well, I would still strongly suggest not ignoring fluids during a marathon, especially a warm weather marathon. However, don’t go to extremes. I recall a few individuals telling me that I should follow their hydration plans because they actually gained weight during marathons. Why should we believe that this is ideal? It’s been shown that the best marathoners tend to lose weight during marathons, typically in the range of 5% of body weight but some even more. Now, we have more evidence that this singular focus on hydration may not help.

Instead, we should be focused on not breaking down our muscles. So how do we do that? We train our muscles. Nothing all that new here. Lots of long runs, lots of volume at faster paces. In addition, though, I think this suggests again the importance of not going out too fast. If you go out too fast, your muscles are going to break down earlier. This will reduce their ability to keep performing at an optimal level earlier than if you go out on pace or even negative split a bit.

With Boston coming, here’s another thought. The early miles are downhill. Getting too carried away on early downhills will damage your muscles, especially the quads, even more. We all know (I hope) it’s important to not get too carried away early at Boston. This likely explains one reason for that. Your muscles will break down earlier and you’ll again lose your ability to perform at an optimal level earlier than if you play it safe on the early downhills.