Diving Into First Base: Maybe Not Crazy

“Chester wouldn’t play baseball unless Wilson played, and they never swung at the first pitch or slid headfirst.” — Chester’s Way, by Kevin Henkes

Most of us have been taught that running through the bag is unequivocally faster than diving into it. Those who dive into first base are often ridiculed for doing so, risking injury to themselves while simultaneously making themselves less likely to beat the throw. However, a new way of thinking about the physical effects on the runner as he dives through the bag — pioneered by the father/son duo that make up “Baseball con Ciencia” — shows that the diving runner could close the distance to the first base bag at a faster rate. Theoretically.

Let’s put aside the risk of injury for now. Diving into the first base bag puts appendages at risk that would not having anything to do with running through that same bag. But that’s another topic. For now, we’re just concerned with the physics of it all.

For now, let’s just talk about the dive into the bag in three parts, as Norberto Rivas Sr and Jr have done on their blog.

The Preparation for the Jump
In order to jump down towards the bag, the runner has to get more horizontal. That’s just how it works. Getting horizontal may not seem to be an advantageous thing in itself, but getting there does two things that help. In going towards the earth, your body is allowing gravity to help it lean forward. This stretches out your stride, as well. Here’s what it looks like on a collection of stills from Baseball con Ciencia:

Diving angle drop gravity center

By the calculations of the Rivas duo, this step gives the diver a ten centimeter advantage over the runner. Not large, but it adds up.

The Jump
There are two advantages to jumping.

The first is mechanical or muscular. After preparing to jump, your body is pointed in one direction and the lunge can be one last explosive movement from your legs. In other words, while you are running upright, you’re using your muscles to push both horizontally and vertically. In the dive, you’re doing a squat, and pushing entirely in one direction.

It’s certainly possible that, in some sports, your vertical muscles would be less developed than your horizontal ones. Long distance running, perhaps. But short distance runners and baseball players usually develop both aspects of their muscles, as recent running theory has shown is a smart idea. So if you do squats, that dive can be powerful, as it fully uses one of the largest muscles in your body to push in one direction. You can read a little more about this phenomenon in this excellent post by David Kagan on The Hardball Times.

The second advantage to jumping comes from the fact of flight. You’re no longer connected to the ground, and you are allowing gravity to fuel your flight as you fall closer to the base.

There is some deceleration due to air friction — Physics professor Alan Nathan called air friction’s impact minimal in this situation — but then there’s actually acceleration on the second half of the fall according to Rivas. Rivas explained in an email. “We found a deceleration, as expected, from 9 m/s to 8.35 m/s on the first 1.08 meters of hip flight,” he admitted. “But on the second 1,05 m. of flight, we register an acceleration, passing from 8.35 m/s to 8.68 m/s. This acceleration was limited, because, as soon the hands’ friction with the floor occurs, the deceleration by body/floor friction begins.”

The Rivases estimate that the explosion plus the flight increases the divers’ advantage over the runners by .71m, and made a video showing the difference in controlled conditions — one runner, synched to himself to show the advantage.

They key to maintaining the advantage is technique. According to Rivas, “The average velocity reached by the runner in the last long step is 9.5 m/s. The average velocity of first .6 meter of sliding is 6.2 m/s, and the average velocity of full body sliding was 5.2 m/s.” Since the diver had a .81m headstart at the end of his dive (25.6 inches), it should take much more than a meter (three feet) of sliding for the runner to overtake the diver.

Nathan, when contacted, felt it is possible that, under the right conditions, the diver could beat the runner. He wasn’t sure about Rivas’ explanations, though. “It could be simpler — you’re stretching your hand out, and the extremity of your body is touching the bag before the rest of your body.”

The roles of gravity and air friction might be overrated in this analysis, he felt, but he did admit that gravity would give your body an assist by “helping to provide the torque” necessary in getting into a diving position. That links up at least generally with what the Rivases say about the benefits of the diving position above. If your technique is right, gravity helps your body along.

But really, the whole advantage gained throughout the dive depends on technique, according to the Rivas family. Their main critiques of the ESPN Sports Science takedown of diving had to do with two points.

One, they felt that Sports Science didn’t make sure that the two runners being compared were at the same velocity going into the slide, which might be a matter of science or technique.

Two, they felt that the example runner did not make enough of the muscular advantage gained by lunging. You’ll see Barry Larkin and Harold Reynolds discuss some of the proper technique of running into a dive into first here. They even mention the aspect of keeping the sliding distance short. Rivas feels that the proper technique has a runner beginning the process at 23 feet, diving at 13 feet, and sliding about a foot or less to the bag.

And, let’s return to the injury factor that we left alone at the beginning of this piece. Even if Nathan believed it was possible for the diver to beat the runner, he thought it was a dangerous activity, particularly since he felt the runner should literally be diving straight for the bag.

Rivas once again felt that technique was the answer here, too. He pointed out that Brett Gardner does a great job of sliding on his wrists, not his palms, so that he can keep his fingers up, and included a still of Gardner sliding as a reference point.

before impact

In the opinion of Rivas, the action is low risk with the right approach. But it does seem like a lot of this hangs on technique. You certainly wouldn’t want your Josh Hamiltons sliding into first base regularly; that’s an easy way to get hurt.

But your Brett Gardners? They are used to sliding head first, and they know how to use their last explosive movement going into the slide correctly. They might actually get an advantage from diving into that first base bag. At the very least, it might not slow them down enough to be worth all the outrage.

With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.

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Captain Tenneal
7 years ago

Again, why do people refuse to believe this? You don’t see outfielders trying to run out every ball; they dive when it’s too far away to reach. It’s nice to see the physics and whatnot behind this, though.

Michael Sweeney
7 years ago

Outfielders dive because you cannot catch a ball with your feet.

The case for diving into first would be ironclad if you had to touch the base with your hand.

Kennesaw State University
7 years ago

I replied without even seeing yours first… I wasn’t copying you, I swear! 😀

Captain Tenneal
7 years ago

Yes, I know that, and I should have mentioned something about it. Even if they were only trying to kick it there is just no way to reach a bunch of those balls. There aren’t a lot of chances for shoestring catches.

7 years ago

Diving in the field also gives you the extra time it takes for the ball to travel from your upper body to the level you reach in your dive. Not the case for first base.

7 years ago

If your suggestion is correct, wouldn’t we expect soccer players to never making diving header plays? I mean, they CAN make the play with their feet. Why not do so?

I imagine it is because they can get their head to the ball with a diving motion faster than they can get their feet there by running. I suspect THAT is the same general principle behind outfielders diving.

7 years ago
Reply to  drew_willy

What? No, soccer plays CAN’T make all plays with their feet. If the ball is travelling in front of the player, perpendicular to the players path at a good clip, at say 6 feet high, a header is pretty much the only way to make contact with the ball.
Your analogy doesnt really work.

7 years ago
Reply to  drew_willy


I don’t know why the website won’t let me reply specifically to your comment. Best attempt I can make here.

Nothing in what I wrote suggested that soccer players will be capable of making EVERY play with their feet. Further, what I wrote ought to have suggested that I was referring to plays where the ball is significantly nearer to the ground than what you have described (6ft off the ground); that is why I posted in response to a discussion of diving catches in the outfield – a scenario in which the ball is near to the ground. I thought it would’ve been clear that I was discussing cases where the ball is low, not up at 6 ft, which would obviously be disanalogous to a diving catch in the outfield.

Maybe this Ronaldo clip – https://www.youtube.com/watch?v=06vWyHbeu3A – gets closer to what I mean. Sure, he isn’t on the ground, but I think it is clear that he heads the ball well lower than 6ft, and I would argue the ball was low enough that he could’ve made a play with his legs (or at the very least his torso). Why didn’t he do so? I *suspect* it is because diving for a header was actually faster than the alternative.

Or how about this clip? https://www.youtube.com/watch?v=Ev1S8quL9rE The dude pretty clearly misses, but the intent is there. Why not just lunge at the ball with his feet? Wouldn’t that be faster, under Sweeney’s thinking?

Kennesaw State University
7 years ago

Because just touching the ball with your foot doesn’t qualify as an out, but touching the base with your foot (could) qualify as being safe.

7 years ago

If you could catch with your foot then outfielders wouldn’t have to dive to catch a ball. The fact that you can touch the bag with your foot which is naturally closer to the ground gives you another advantage. When running to the base, your hand will need to travel a further distance than your foot to reach the base. It might be that under perfect conditions you can make it to the base the slightest fraction of a second faster but in reality, over 90% of the time, you will slide sub-optimally and make it take longer.

You can find dozens of studies showing that it takes longer to slide than to run through the base and just because one person publishes a something showing a different result doesn’t invalidate all the other studies on the subject. I appreciate that Eno is looking at a different approach since I feel like he explores the other side of what is widely accepted better than most do, I just don’t think that this invalidates years of research.

Captain Tenneal
7 years ago
Reply to  Los

Actually, I’ve always agreed with this point, too. I think it is too difficult to be consistently perfect for diving to actually be worth it. It’s one of those things that I’d pull out in a desperate situation where I knew I’d be out but maybe a lucky perfect dive gets that extra tenth of a second.

I’m not actually advocating that it be done often, just that it IS viable (potentially).

7 years ago

Except if it’s something you only pull out in desperate situations, you have even less practice at it and are less likely to do it well.