So I’m always seeing exhortations to try to negative split, both in training and in racing. Is there any physiological benefit to this?
absolutely. If you chose your first split right, then run even or slightly negative (assuming you’re completely spent at the end), then you have gone as fast as you possible could have. Running negative splits is a great way to keep you effort consistant.
If you run a 5-min fasster second half, you’re not pushing yourself hard enough and if you run 5 minutes slower, you are pushing yourself early. A more consistant effort will yeild a better time for the same workload.
You mean like this?
**A more consistant effort will yeild a better time for the same workload. **
That would be my feeling, generally, but it seems a little at odds with the idea of a negative split, no?
No, that’s fartlick.
-1 second is still a negative split. I see no advantage of running a -5 min split. That just means you didn’t go hard enough. The key is to run hard for the first half… harder than you would expect yourself to keep up, then watch the clock on the home stretch.
I don’t normally keep track of 1/2 split times on long runs. I keep track of what my mile-pace is by timeing my runs and knowing where the 2,3,4,5, etc mile-marks are. I became obsessed with split while becoming a decent 800m runner in high school, where it has always been a challenge for me to run even splits. I don’t think using 1/2 run splits is useful over 3 mile runs because over 3 miles, your body and your chi changes with every mile. Mile 4 may feel like shit, but you may fly through mile 7. I will, however, try to average a predetermined rate of speed. Like, if I go out for 8 miles, I will want to be back home at 60 min, no matter how shitty mile 4 was.
Those are my thoughts. I’m not a coach, doctor, or PT, just a runner.
God, that made my day, right there.
Negative splits are always the way to go.
Every endurance athlete should get behind the wheel of a Toyota Prius for a week and keep their eye on the MPG readout. Humans are not unlike internal combustion engines when it comes to burning fuel, a lot of accelerating and slowing, or driving very fast for a period of time burns fuel at a much higher rate than if the driver kept at a constant 56 mph.
When running long distances such as a marathon fuel management is crucial. Your muscles can only store so much glycogen and you are extremely limited in how much you can absorb while running, so you should try to lock in at your goal pace and run as evenly as possible.
Most coaches advocate negative splits because 99% of runners either over estimate their fitness or get carried away in the early miles and end up crashing badly later in the race. Holding back in the early part of the race is a good habit to get into and 9 times out of 10 it will get you to the finish line faster than going out at your projected goal pace.
In my last good marathon I hit the halfway averaging about 6:07, from 13 to 18 I averaged 5:55, and 18 to 26 I averaged sub 5:50 with mile 26 my fastest of the day in 5:25. This is a little too conservative to be completely ideal because I was lacking a little confidence in my fitness because of a bad tuneup race but that ended up being a blessing in disguise and I ran a PR.
Running negative splits on training runs is a very good habit to develop and it will pay dividends when you race.
Matt, it seems to me that the main issue you raise is a matter of pacing experience. While I agree that negative splits might be helpful in keeping one from blowing up too quickly, it also seems to me that running a constant pace, if one can, would be more efficient. To take your car example, what’s more efficient- driving at 56 mph the whole time, or driving at 45 mph, then 50 mph, then 55 mph, then 60 mph over a given distance, averaging out to 56 mph?
Locking in at a constant pace is always the most efficient way to run…the only problem with that is that the vast majority of runners lock in at too fast a pace early on abd blow up. If you look at any of the big city marathon results and study the splits you’ll see that outside the top 50 or so finishers, the vast majority of runners run big positive splits.
Negatives splits are not as efficient as running a constant pace but if you try to go with a constant pace every time you’re gonna blow up a in pretty good proportion of your races. Perfection is hard to attain…better to hold back early, and lose a little time than blow up late and lose A LOT of time.
I ran the LA marathon last year and went through the half in a very conservative 1:19 (it was a very hot day), by mile 18 I was toast and was struggling to hold 7 minute pace, by mile 22 I was running 8 minute miles. There were 40,000 runners behind me and in the last miserable 10 miles of my race ony one person passed me…I kept waiting for hoardes of runners to come streaming by but they never came.
Negatives splits are not as efficient as running a constant pace but if you try to go with a constant pace every time you’re gonna blow up a in pretty good proportion of your races.
OK, that’s more along the lines of what I’m asking, thanks. I agree that there are times when it’s probably prudent to negative split, but a lot of the stuff I see about it makes it sound like a victory in and of itself. “Great training run- I ran negative splits!!” Great- so what? “Awesome race- I ran the second half faster than the first!” OK, but it would have been better to run consistently, right?
Like you say, it’s a necessary skill to have, but I don’t see any physiological benefit to it.
I agree w/ what Matt is saying, from my own very limited experience, and also from what I saw at the 10k I did on Sunday. It is a strategy that is somewhat easier to attain (or attempt to) than keeping an absolutely steady pace.
(FWIW, back in the day 20+ yrs ago when I was a HS 800m runner, all my PR’s were negative splits)
I screwed up (I’m a rookie at this stuff all over again) and went out a tad too fast, even tho it didn’t seem so at the time. So, I went out about 5-10 secs faster than my per-mile race pace for mile 1, and then paid for it by running 5-10 secs slower per mile for the other 5.2 miles. RATS!!!
Amazingly, even tho I felt like I was going backwards from the turnaround until about halfway back, I only got passed by maybe 3 people (out of a field of 550). Probably because, everybody else behind me screwed up even bigger than I did, and went out WAY too fast. << I kept waiting for hoardes of runners to come streaming by but they never came.>> Exactly.
PS - Thanks for the race tips Matt!!! I didn’t quite hit my goal time, but still PR’d over my previous “race” 10k efforts by about 50 seconds. 
And here’s where I get confused: What about locking in at a steady HR, rather than a steady pace per mile? If I’m doing an IM at roughly 70-75% of max HR(as rcommended by several coaches) I’ll never negative split due to HR drift. Yet I know I haven’t gone out too hard or too easy becasue my level of intensity was where it should be.
Frank
I’ll never negative split due to HR drift.
And you’ll never negative split if you’re stuck to a too literal idea of perceived effort as a guide, either, since the sixth mile is always going to be harder than the first at the same speed. You have to be experienced enough to take these variations into account.
To move the discussion away from running a bit and into cycling, this might be a good arguement for racing with power instead of HR.
In races, only time I think about negative splits is if I haven’t done adequate work to know how to pace myself evenly. I’m a decent runner (not that fast, but I’ve been doing it for a while) and I generally know what a 10k effort should feel like. I’m quite a novice at swimming and biking, so it ensures that I don’t die 3/4 of the way through. I start with what I think will be a good effort, and back off just a little bit for the first half. Then over the last half build a little bit towards the end if I have it. I’d like to get away from that, but it often seems like it’ll be years before I have that sort of knowledge and experience in cycling and swimming.
In training, again running I go for even splits because I know how. I’m clueless in cycling and swimming. I really focus on it in swimming because I really slow down when I get tired. What seems like a negative split is often even when I look at the clock.
As for going out too fast, I’m constantly amazed at how the entire field will do that. I’ve been racing (this time around) for about a year now, and I’ve gotten used to it. It would be nice if I could pace off people, but I’ve found it best to just ignore everyone for the first mile or two.
My impression has always been that negative splits is the way to go for racing (for what seems like obvious reasons), but not all or most training. Perhaps race-simulation training…?
I’m like you artrent, a half decent runner giving triathlons a go. Wildflower was my first real one (I did a fun sprint last year) …I can’t access the results because of some dumb firewall but to the best of my recollection I was about 1100th overall in the swim, 400 something on the bike and I think 36th on the run…probably about 3000th on transition times too.
I knew I sucked in the water but I thought my running fitness would translate a little better to the bike. I guess I need to spend more time in the saddle…and get some aerobars.
“And you’ll never negative split if you’re stuck to a too literal idea of perceived effort as a guide, either, since the sixth mile is always going to be harder than the first at the same speed. You have to be experienced enough to take these variations into account.”
Not to be argumentative or dense BUT I’m not talking about perceived effort but rather actual effort as indicated by HR. Of course the 6th or 26th mile will be harder than the first at the same speed. But not nearly so if they are run at the same HR. Let’s say it was a tough swim and hard bike. What does that do to the run pace I’ve planned on? How much slower should I go out in order to negative split? Why not just determine the HR I know I can sustain instead of guessing at the pace I think I can sustain? But then, to borrow your phrase, you do have to be experienced enough to know your sustainable HR. And, yes, at some point in the raceyou need to forget about heart rate and just bust it!
Frank
Not to be argumentative or dense No worries. I might be a little dense myself, but I’m not trying to be argumentative, either. Just kicking an idea back and forth a little to see if I can’t learn sumfin.
I’m not talking about perceived effort but rather actual effort as indicated by HR. Yeah, I know- I was just pointing out that HR drift and perceived effort might be somewhat similar in that they change over time for the same effort, and you just have to take that into account. Just as you would try to maintain the same speed at mile five, even though your perceived effort has increased, you’re going to try to maintain the same speed, even though your HR has drifted up some, right?
Let’s say it was a tough swim and hard bike. What does that do to the run pace I’ve planned on? How much slower should I go out in order to negative split? Why not just determine the HR I know I can sustain instead of guessing at the pace I think I can sustain?
That’s an interesting point. Let’s say you planned on running at 75% of max HR, but your swim and bike were a lot harder than you expected. Can you finish the run while staying at 75% of max?
I did my first 1/2 marathon over the weekend, and I was anerobic (and above my target hr) standing at the start line.
The gun hadn’t gone off yet, and I thought shoot, I better slow down.
My hr ended up being 10-15 beats higher than expected (and during training) the whole race, with an ave. hr for the last 4-5 miles nearing 90%. I didn’t even think that was possible. I did negative split slightly and feel pretty good the whole way however. If I tried to run at some kind of HR pace it would have been a complete joke.