What Do Hockey Visors and Birth Control Hormone Shots Have in Common?

The New York Times recently reported that using Depo-Provera, one of the most popular contraceptives in eastern and southern Africa, may increase a person’s risk of transmitting HIV. I fear this is a case for The Guardian‘s Ben Goldacre… where a study gets a bit (understatement) too much spin in the media. I first became aware of this while in Uganda and saw the following headline in the local paper: “The injectable contraceptive that could double the risk of women contracting HIV.” That sure sounds like the shot itself does something. Or could this instead be a by-product of behavior change? Huge difference if you are deciding what birth control to use!

The Times article cited a study recently published in The Lancet, which showed that women using hormonal contraception—primarily the injection more commonly known in the U.S. by its brand name, Depo-Provera—were twice as likely to acquire HIV from their infected partners, and twice as likely to transmit the virus to their HIV-negative partners.

Whether this is because of biophysical changes or behavior changes is not obvious. And the paper acknowledges this. Several studies have questioned whether hormonal contraceptives have physiological effects beyond pregnancy prevention, perhaps by altering hormone levels in genital tissue or vaginal lining. To support that possibility, this study tests for the concentration of the HIV virus in women’s vaginal fluid, and finds that women using hormonal contraceptives have higher concentrations of the virus than women who are not using the same birth control method, even though the level of HIV in their blood is no different.

But this test still does not disprove that women may be acting differently from the ones using other forms of birth control. Rather than the hormone itself exacerbating the HIV epidemic, this might just be another example of the Peltzman effect: drivers wearing seatbelts feel more secure, and therefore drive less carefully; the number of traffic accidents goes up, and the benefit of wearing a seatbelt is offset. Women using hormonal contraception may feel more protected against pregnancy, and so take fewer precautions against other risky sexual behaviors, leading to increased transmission of HIV and other sexually transmitted diseases. Or, women lose the socially-acceptable reason for wearing a condom (“I don’t want to get pregnant”) and are stuck having to resort to a trickier message to an impending sexual partner (“I don’t trust you to not have HIV.”) So they end up having more unprotected sex.

In The Lancet study, all contraceptive use was self-reported, including hormonal contraceptives and condoms. This is obviously not easy data to collect, in a truthful way (see earlier post on List Randomization for one technique). Still, there is some evidence that people using hormonal contraceptives engaged in riskier sexual behavior. For women with HIV, the ones using hormonal contraception were slightly—and statistically significantly—more likely to have sex without a condom with their HIV-negative partners (12.9 percent) compared to those not using hormonal contraception (10.1 percent).

The World Health Organization is now reconsidering its recommendations on contraceptives, while international health organizations like FHI 360 were quick to respond that more rigorous evaluation is needed. Clearly a case of unintended consequences… personally my hope (hopefully not falsely optimistic) is that the lesson is to integrate lessons about risks of HIV transmission; or perhaps the answer is more private administration of Depo-Provera? Certainly at a minimum this is a call for a better understanding of the behavior change.

And what’s all this have to do with hockey? This recent paper by Alberto Chong and Pascual Restrepo finds that hockey players got more penalty time after switching to helmets with visors, ie, ones that protect them a bit more.

While we’re on the topic of hockey, can someone more informed than I explain why they don’t make Sumo wrestlers goalies? Or a Sumo goalie and one Sumo defender? Is it because it would shift the equilibrium too fast and everyone would do it, and then just cause rule changes to prohibit it? Or do existing rules prohibit it in some way? Or, is it just too hard to find one who can ice skate?



Maybe it's because hockey coaches read Freakonomics and don't trust sumo wrestlers.


I have wondered the exact same thing about hockey for years. Why not find a player large enough to basically cover (read: engulf) the entire goal?

Joshua Northey

I just played a hockey game a couple hours ago.

A) The goal is 4ft high by 6 ft wide, you wont actually find people big enough to cover the 24ft^2. Particularly since people are generally taller than they are wide.

More importantly:

C) Even at my level (30 and 40 year old men's league players who were not quite good enough to play Division 1 in college) we are good enough to put the puck in very small spaces. Just today I got two goals in slots that were probably 6"X6". Even with a very big person in there are going to be a lot of those slots in a 4'X6' goal and they won't have the mobility to close them that more limber goalies do.

To be fair a lot of the best goalies are very tall, because being larger does help, but at the higher levels they are also generally extremely thin because quickness is exceedingly important.


Goalie's themselves are often the smallest (body mass-wise, not height-wise) people on a hockey team. They excel because of flexibility and quickness, not because they naturally take up space. A more pertinent question might be, "why don't they make ninjas into hockey goalies?"


Re: Sumo hockey goalies, I imagine part of it is that you couldn't get them on ice skates. Another reason is that some teams value a puck moving goalie ( like Brodeur, Thomas, etc) to help negate the opposing team's offensive set up. I can't imagine a Sumo goalie would be to mobile or nimble with the puck.

It would make the elusive "goalie fight" that much more interesting though.....


They ran some tests on sports science pertaining to your sumo question. video here: http://www.youtube.com/watch?v=sP8ZVWiZUMA


Well the puck is so small they could probably get it through the sumo wrestlers legs and he wouldn't be able to defend the goal due to his inability to bend that way...


Your last sentence is the reason: can't find a sumo wrestler who can skate. Also, the sumo wrestler would need to be 6' wide.


The biggest problem with a sumo goalie is the rules governing equipment. There is a maximum size for goalie pads, and any person large enough to cover the net would be far too large to be protected. A sumo goalie could theoretically play, but they'd be taking slap shots (sometimes at more than 100 mph) to almost completely unprotected parts of the body. There's a few other issues (the goalie is also required to skate to the net under their own power, and his team would have to score against a defense that's sure to take cheapshots on such an unsportsmanlike opponent), but the pads are the primary issue.

Andrew Collins

Hockey question, Canadian to the rescue.

There is no rule against this practice but there are rules limiting the size of a goaltenders pads and equipment. To find a goalie large enough to cover the entire net while keeping his body protected for the puck that can be shot at over 100 mph would be impossible.

Many times you see larger guys playing goalie for recreational or beer league hockey because they are simply too slow to keep up with play as a player. The goalie position requires too much speed and quick reflexes for these guys to be effective (aside from Tim Thomas and Martin Brodeur of course).


On the topic of sumo goalie. Not totally scientific but it has been 'tested' on Sports Science with NHLer George Parros. http://www.youtube.com/watch?v=sP8ZVWiZUMA is the video.


I read something a while back that pondered whether head & neck injuries were more common in American football (NFL) due to helmets & pads...the idea being that you're perhaps more likely to launch your head into someone if it's protected by a facemask and helmet.


The reason someone hasn't done this is because no matter how big a goalie is, there are still pad restrictions. So a huge goalie that couldn't butterfly would be extremely set back, and they would just shoot low on him every time. Also, agility is a big part of being a goalie (i.e. moving side to side) which I'm assuming a sumo wrestler would have trouble with.


The issue is mechanical advantage. It helps in basketball to be tall but very tall people are often less coordinated and/or slower afoot so we've seen large numbers of very large players fail in the NBA because the game requires movement both up and down the court and in defense around the basket. Mechanical advantage shifts as the requirements of the game (and the rules) demand.

Same for hockey. A very large player has a mechanical advantage blocking the net but pucks are shot at angles and into small spaces so the advantage shifts to those who can cover the net AND move about quickly AND cover the small spaces quickly AND get to the puck behind the net to control and clear it from their end. There have been large goalies - maybe the best, Ken Dryden, was (and I assume still is) 6'4" - but few are able to shift around and react well enough to play at a top level.

The visor paper is cool but more work needs to be done about the kinds of penalties taken. Do players who use visors become generally more aggressive or are they taking more penalties of a certain kind, like high sticking or slashing. If you wear a visor, you might feel more protected against high sticking so you do it more. It's a question if there is more charging, etc.



Aside from the astute reasons already submitted, another reason a sumo goalie isn't the best option is that goalies are not there to simply block the puck blindly from going in the net. An effective goalie as to _catch_ the puck as often as he can to prevent rebounds and so he can distribute the puck to his defenders or earn a face-off. Also, direction of the inevitable rebounds is key - he'll want to angle them to the corners and not out in the face of the goal. Moreover, goalies play the puck when it is dumped in by the opposing team and there is no immediate threat to the goal.

Without these skills, who needs human goalies anyway? May as well just put a hunk of plywood in the goal and make the game more like basketball. (Not a serious suggestion.)


The problem is that even a very fat guy laying down on his side in front of the net would leave a few holes where his legs are, and hockey forwards are very good at putting the puck into small holes (http://www.youtube.com/watch?v=UG7fWRI1akE&feature=player_embedded), particularly in the corners of the net.


Because when they fall they have to get up. Fast.

I think the same phenom happened when the NHL players started wearing helmets. There were more injuries: cuts, head injuries, etc. because players were less disciplined with their sticks.


No hockey player has been worried about getting a concussion from a hockey stick. Maybe helmets have made the intensity of headshots increase, but not cuts.

Once visors become mandatory I could see stick use being less disciplined but former NHL-ref Kerry Fraser recently noted that thing only thing that has made stick use more responsible (over his 20+ years) has been penalties for high-sticking. (And that won't change once visors are mandatory.)


Any sumo wrestler would learn to skate given the potential paycheque of a quality NHL-calibre goalie. Ed Jovanoski (an all-star defenseman is his heyday) didn't learn to skate until he was 13, for instance.

The net is 6' wide. No one is big enough to cover all that up and at some point you're going to exchange coverage for motility, making it easy to score in whatever openings are left.


Sumo wrestlers are probably quick and mobile for their size and big/tall - all good things for a hockey goalie.

That said, a sumo wrestler is good at knocking people over and maybe falling gracefully. However, there's no need for a sumo wrestler to get up quickly after being knocked down. That would be a problem in hockey.

Probably the most important thing, after skating, is vision and anticipation. What's going to happen and when. Sumo wrestling is of no help.