Question: I’ve been reading your blogs about steady state vs. interval training and they have been quite eye opening. In your article, “pole vault your way to a hot body” you talked a lot about tempo work in 400m runners. My question is, is this tempo running in kind of a low intensity interval training type situation better than long distance duration runs. If so, what is the science behind it? The way I have learned is your body begins to burn fat for fuel after about 15 minutes of aerobic work when it reaches the high oxygen consumption it needs to burn the fat. So to me, it seems like a good hour long run would yield better fat loss results than anything else.
Answer: The thing to keep in mind about the ‘extensive tempo’ running that sprinters commonly do is that the goal is not specifically aimed at fat loss (even if keeping the athletes lean is often a consequence of that type of training). Rather, it’s a way to get a large volume of relatively lower intensity work (to build work capacity, recovery, etc) while also getting in some technical work without having to slog endless miles.
Much of this reflects the odd situation that sprinters, and this is especially true in the middle distances of 400-800m have to deal with. They need the high power output for top speed but they also need the aerobic development and endurance that will allow them to
1. Be able to handle the high training volumes
‘2. Not run out of gas towards the end of the race
This puts them in a strange place metabolically, too much endless endurance work tends to compromise top speed and power output. But they need the aerobic development for the reasons stated above. Tangentially, it’s turning out (and cutting edge coaches have known this for years) that the size of the aerobic engine has a huge impact on how well the body handles acid generation during high-intensity activity.
Mitochondria actually have lactate transporters and having better developed aerobic capacity ends up improving anaerobic capacity as well. And developing this capacity takes much less out of the athlete then grinding out lots of anaerobic style intervals (which tend to be mentally and physically exhausting). As far as the fat loss question, the thing to remember is that typically the rest intervals are kept fairly short during this type of extensive tempo training. You reach a pseudo-aerobic steady state of sorts because you’re not getting complete rests between sets.
Which would explain a lot of why it has the effects that it has. Since the speed of the ‘on’ bits is also faster, it’s probably a bit more specific to the requirements of a 400m sprinter than slogging slow miles (although, as noted in one of my blog posts, they do some steady state training as well). But the overall stress of the workout still tends to be towards the lower intensity end of things since the run bits are kept short.
Will it necessarily be ‘better’ than an hour hard run? Probably not because, if nothing else, the hour run will burn far more calories (which is still the ultimate determinant of fat loss) than a 30 minute tempo session or what have you. But, as noted above, it’s more specific to what those distance sprinters need and the volume will, as a consequence, help to keep them leaner. Hope that clears things up.