Julianna Pena's injury story, however actual or fictionalized, caught my attention. I had never considered it fully, but her situation sparked a thought I've been unable to shake: women face a training environment that is essentially impossible to replicate for men.

Men face no gender where they are at near constant disadvantage when it comes to physical prowess. Whatever challenges they may face in the course of their career, it is highly unlikely men will ever succumb to the contours of gender discrimination at any gym. And while female fighters glean some benefit from training with men, the inverse isn't necessarily true, at least not to the same degree. Women also must deal with a gender in predominant number that, as Pena's situation underscores, offer the significant potential for injury both small and catastrophic.

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In short, I wonder what it's all like. Are men a 'tax' women fighters have to pay in order to succeed? Do they need them at all? Certainly there's some benefit and absolute necessity to training with men, but is it just stronger and faster training partners? Is the only downside merely injury or is there more to the story?

When it comes to being a professional female mixed martial arts fighter, what is the truth about the ups, downs and unknowns when it comes to training with men?

To help with perspective, I consulted a few experts - Invicta matchmaker, UFC and Strikeforce veteran Julie Kedzie; UFC and former Strikeforce bantamweight champion Sarah Kaufman; Invicta atomweight champion Michelle Waterson; and former Invicta atomweight champion Jessica Penne - on the risks, rewards and bizarre circumstances women encounter when it comes to training with men.

Is training with men a requirement to be a world-class competitor?

Kedzie: "That's a weird question because I don't think you can be world-class fighter without training with good training partners. Whether they're male or female, I think you just have to have the right training partners. If you have a whole bunch of men, but they suck, then no, you're not going to be a world class fighter. If you have a whole bunch of women and they suck, you're not going to be a world-class fighter. If you have a whole bunch of men that are really good, then you'll probably rise to the occasion, likewise with women."

Waterson: "When we fight, we fight against women and women fight differently than men. I feel like women are a little bit more aggressive, a little bit more out of control, a little bit more emotional when it comes to fighting. If you're always training with men, you don't get those aspects of the fight game. Also, when you do train with women, it's competition. The person across from you that you're training with, even though they're your training partner, deep in their head they're to prove something to you and to themselves."

What is the best aspect of training with men?

Penne: "I feel like their intensity is really beneficial. Also, they're stronger, faster than females, so you get used to that kind of speed going to females sometimes, it's a little bit more beneficial.

You also get used to carrying a lot more weight than somebody your own size. You have to carry heavier loads and when you're fighting a female your own size, it feels a lot easier."

Waterson: "I think it goes back to what kind of men you're training with. I feel like the smaller guys are good because they give you the speed. A lot of the guys I train with, they don't go hard because they don't want to try to hurt you, but they give you the speed and the pressure that is needed to get better.

"When I started fighting, I was training with a lot of males. I kind of became a counter fighter. I learned how to counter off of other people's movements. You have to learn how to be a lot more technical when you training someone that's over powering you."

Kedzie: "Their durability. You can hit a man pretty hard. They may say 'ow', but they probably won't and that might be their ego. You can get a sense of how hard you can hit.

"It's nice to go with someone that's stronger than you. Many women are stronger than me as well, but it's nice to go with someone that's always stronger than me so that I can get a sense of how hard to go in an actual fight."

What is the worst aspect of training with men?

Kedzie: "They always try to correct you. Especially if you're the lone women in the room, everybody just finds some reason to correct you, some reason to try and teach you more when sometimes you're just there for your workout. That drives me bananas. I have a lot of confidence in my own abilities. 'Oh, that's wrong! That's wrong' tends to get my hackles up even more.

'Oh, she's a girl. Let's show her what to do.' I hate that."

Penne: "There's more potential for injury. My training partners that I have at Reign MMA are extremely trustworthy. I trust them. I've known them for years. I've trained with them for years. I trust them that they won't retaliate because that's been an issue in the past at other gyms I've been to. Guys have some ego problems and it has led to me getting injured and no longer training with those people."

Waterson: "Sometimes if a male has an ego because for a male, it's a lose-lose for them. If they go too easy on you and you whip their ass, then they got beat by a girl. If they beat you up, they're being an asshole because you beat up a girl.

I really do think it's on the person. That's just my thought for never ever comparing males to females when I'm training. When I'm going to the gym, everybody is my training partners. I don't view them male-female. I have a lot of male training partners I enjoy rolling with more than females just because they give me better work. I think whether it's male or female, they're certain people you click with and you're able to mesh well with and train better with."

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Have you personally experienced any training accidents from training with men?

Kedzie: "The only times I've been knocked out in training has been by men, not women. I would take the blame on myself for that because it wasn't that they were going too hard for me. It was mostly they were going light and I was going to hard.

It's not that they would actually have too much pressure on me, but that I would slam into them."

Penne: "I've gotten my ribs popped by guys. Accidents happen when guys are so much bigger and sometimes egos get involved. They can go a little bit too hard.

It may not be a big deal to women at competing at 25, 35, 45, but I'm a 105-er. I'm the smallest person in there. It's not an even playing field.

Although, what's funny is my coach Mark [Munoz], who fights at 185, will come in and he'll move around with me. I've never been injured training with him. He's a professional, great athlete and knows how to move his body. He knows how to not hurt me."

Everyone knows men can be faster or stronger. Mechanically, are there any other differences?

Kaufman: "You definitely benefit from working with people who inherently, even if they're the same size as you, are going to have more strength. Not necessarily better endurance, but their lung capacity has the potential to be better. Their balance is different, not necessarily better or worse.

But things are different. They have different body structures and different muscle capacities, so being able to be pushed, it can be a benefit, but you can also sometimes get frustrated because I'm trying to do things in training that in fights have worked for me, but with people who are stronger, faster, more explosive in that regard. You can get frustrated in training because you can be like, 'Oh, I'm getting in. I have my hands closed, it's a super deep shot and somehow, they muscle out of it.' And my coach has to sit there and say, 'You know that they're 20 pounds heavier and they're a dude, right?

You have to think about that, but you don't want to think about that."

Penne: "If we're working clinch takedowns, a man's upper body is a lot broader than a woman's so you get used to having a certain grip, gripping a certain way and when you go with a female, they're a lot smaller, so all of sudden your grip is loose and it messes with your technique."

"Particularly with guard passing, men are not nearly as flexible as females. So, in my opinion, it's a lot easier to pass males' guards than it is females. Me, I'm extremely flexible and I never really had to deal with flexibility from a male training partner the way I did from a female training partners."

Ok, what about women who've almost exclusively trained with men and only now have female training partners? What have been the benefits of that change?

Penne: "It's helped a lot just having somebody more realistic to what you're going to be fighting. Men and women, our bodies are so different. We move differently. It's really been beneficial. Not to mention, being able to apply the techniques you drill in class. I feel like my learning curve has gone up because I've had female training partners.

It's been really beneficial in terms of learning techniques. It's a lot harder to do them on male training partners because I'm at the smallest weight class there is. Most of the male training partners I have fight at 155. I sometimes get a 135-er in there. The bodies are just so different, it's really beneficial to train with a female."

How do you build the sort of 'trust' needed in your male training partners necessary to get the best, but also safest training possible?

Penne: "It takes a while, honestly. It's like any relationship, you have to build it over time. It takes a lot of practice and communication, just knowing your partner and knowing where they're at. It's nothing you get right off the bat. It's really learned through time and practice and training with partners."

What's the right mix of training you need to be a world-class competitor and stay as safe and healthy as possible?

Kedzie: "I don't think you're missing out on something, but there is a benefit to having female training partners in the sense that you fight women, you don't fight men. I don't know the actual scientific ratio, but there's a muscle density difference you have to deal with with women vs. men. Women tend to be a little more flexible when you put submissions on them.

At least in my experience training with women, our competition level against each other is higher than if I were going with a male training partner because the male training partner will either take it too easy or maybe go hard without meaning to. With a woman, we're basically trying to take each other's heads off the whole time."

Penne: "It would definitely be mixed. I would say 50/50. I would want half male, half female training partners."

Kaufman: "I think whatever works for you, but I do think it's nice to have that balance. As a female training with men, you inherently know they're stronger, they've the potential to be more explosive, they have the potential to be this and that. At least for me, you tend to have a little bit more fight when you have another female who is your size because, in theory, you should be equal or better or maybe they're better, but it pushes you differently.

I think it's definitely good to have both. You can be a world-class female athlete with only females around you. You can also be a world-class athlete with only males around you as long as you have right group who is supportive, great coaching and the ability to let the bad days go and welcome the good days in training, no matter what."

What advice do you have for women who currently train or want to take up mixed martial arts?

Penne: "You really have to be on it with communicating your needs and where you're at. I spent most of my career training with male training partners and always feeling like I had to train with everybody. I wasn't happy if I didn't train with everybody, no matter what size. But in the last year, I've become very vocal about sayings 'yes' or 'no' when people know if I'm injured, had two training sessions before this one. Just really communicate what you need from your training partners and to your coaches. Don't be afraid to say, 'no, thank you.' Don't be afraid to grab somebody if you want them to be your training partner."

Waterson: "For one, be smart. Listen to your body. At the same time, this is a sport not for the weak. You can't fold under pressure. You have to show your worth. I feel like the best way to get someone's respect is to show up and work and not make it a 'Oh, I'm a girl. You should give me this type of respect' or 'You should treat me differently'. When you go into training, it should be, 'I'm a fighter and I'm here to fight. You're my teammate, boy or girl.'"

Kedzie: "If I'm a 135 pound woman, the 135 pound man I'm sparring is going to be stronger than me. When I choose to train with men, I choose to train with more experienced men than less experienced men because they know what they're doing. I know what I'm doing and we can work situational things a little bit more than going ape s--t and trying to take each other's heads off."