Who gets more benefit from the run: a guy running 8 miles in 50 minutes or a guy running 8 miles in 65-70 minutes?

I think the OP is talking about two different runners. In that case, it's a pretty interesting question. If they are running at the same heart rate, I'd say the slower person.

Who really cares about the benefit. If they are both running the respective paces for 'easy' efforts, then Mr. 50 will dominate the other in a race. Remember, racing is absolute (time), any of the relative (HR/effort/pace) crap doesn't matter.

If by "benefit" you mean "oxygen consumption" and "training effect" then faster is better. But doing it within 70 minutes will still produce a nice training effect and will lessen the chance of soft tissue injury.

rojo wrote:

I think the OP is talking about two different runners. In that case, it's a pretty interesting question. If they are running at the same heart rate, I'd say the slower person.

If the OP is talking about two different runners I guess you're right. But obviously eben better would be 70 minutes at 6-minute-pace ;)

milermb wrote:

If they are two different people and assuming the effort level is the same in each case the slower guy has a much harder workout - he is holding the effort for much longer. Which is why Lydiard, for example, in his more recent books talked in terms of time spent runnijg rather than miles covered.

+1

If it's two different runners, for example one young, one old or one with a lot of talent, one with little talent, then the one running for 70 minutes is on a harder run than the one running for 50 minutes if they're both running at the same relative effort level. 4 hour marathon runners have a harder time training for a marathon than 2:45 marathon runners simply because their race takes a much longer time to complete.

hammer everyday wrote:

to improve wrote:

All workouts have the same purpose.

Overall they do but not on an individual basis.

Sure they do, just in smaller increments.

Nobody is talking about eccentric muscle contractions, basically what your body has to do to absorb the shock of your feet hitting the ground. The faster you are moving, the more force you are putting into the ground, and the shock your muscles have to absorb increases exponentially.

If you're defining "benefit" as amount of tissue damage at the fascia/cellular level, which I think you are, then the 50 minute run is better.

steeplechump wrote:

Nobody is talking about eccentric muscle contractions, basically what your body has to do to absorb the shock of your feet hitting the ground. The faster you are moving, the more force you are putting into the ground, and the shock your muscles have to absorb increases exponentially.

If you're defining "benefit" as amount of tissue damage at the fascia/cellular level, which I think you are, then the 50 minute run is better.

Oddly, running a slower pace often beats up the legs more.

half with your GF wrote:

Oddly, running a slower pace often beats up the legs more.

According to science or according to some anecdotes from you and your teammates?

rojo wrote:

I think the OP is talking about two different runners. In that case, it's a pretty interesting question. If they are running at the same heart rate, I'd say the slower person.

Statistically it will be the slower indeed because it has more room for improvement ie the marginal benefit will be greater.

The faster runner will only benefit more than the slower runner from his run if he’s less trained than the slower runner, which is unlikely, but potentially true (think rare, young talent).

They’re both running at same HR but whoever is “newer” to the sport benefits most.

Assuming its the same guy both of these runs provide a different stimulus. So both are beneficial but carry different benefits. My assumption is the 50 minute run would be a long tempo effort for this guy and the 65-70 min would be an easy or recovery run. There are physiological benefits that take place during each run. One run places a greater stress on the runner than the other thus the necessity of a easy run or recovery run. Ideally you are able to run harder more frequently but understand this is a double edged sword. Overloading your system is necessary to create adaptations and improvement yet too much and too frequent overload can lead to burnout/overtraining and injury...this is obviously individualized and depends on background, current fitness, etc. Hard work and recovery are 2 sides of the same train track...each side equally important and supportive to the locomotive utilizing them. You embrace hard work without recovery you end up in a ditch. You embrace recovery without hard work and you end up in a ditch on the other side. Both are necessary in the life of an athlete wishing to make the most of their ability. So to answer your question both. You can't only do one to achieve optimal performance or get the greatest benefit.

steeplechump wrote:

half with your GF wrote:

Oddly, running a slower pace often beats up the legs more.

According to science or according to some anecdotes from you and your teammates?

According to science based anecdotes.