Michelle Trachtenberg, Hayden Panettiere and Joan Cusack talk Ice Princess

Disney's Ice Princess casts Michelle Trachtenberg as a physics whiz who discovers a talent for figure skating. The actress, best known for TV's Buffy, the Vampire Slayer, endured physical training on top of the normal acting rigors to play Casey Carlyle. In a way, this was her Million Dollar Baby.

"I really struggled with the lack of makeup in this role," she joked. "In the physical sense, it is. I trained extremely hard for the movie. When we weren't shooting, I was working, training five hours a day, five days a week, and I had ballet every other day. Was constantly on the ice. And then when we were shooting, I was working seven days a week because five days of shooting and then on the weekends doing all the choreography, learning whatnot, and I was working 20-22 hour days, because I was one of the only adults on the movie. Everyone else was pretty much a minor, so after 10 hours they went home and I was still there on ice skates, working my way around."

The physics were accurate too and sometimes had to be redone after somebody double checked them. "Every theory that I say in the movie, every physic shout out is all correct. In fact, we shot one scene where I say m x a = m mass and all that stuff, and we mixed up a letter, so there's one shot where you're like why are we on the back of her head? Because we looped in the right term, because we didn't want to teach any kids wrong."

With a three year stint on a television show in between movies, and her beginnings on soap operas and sitcoms, Trachtenberg appreciates the differences between media. "The one thing that you don't get with movies is that you don't actually get to talk or experience the people that you're putting these things out for. With sitcoms, the audience is right there. You can hear them laugh immediately. TV it's right away. With movies you gotta wait some time. So it's interesting."

As for returning to TV, and particularly the role of Dawn in Buffy, Trachtenberg prefers not to look backwards. "I'm sure that there was tons of talk. I'd heard something here and there. [I've said] that I never want to play a character again. I don't mean any disrespect for the creators and producers of my previous projects because I never pick a project carelessly. I always have some heart attached to it."

Playing rival ice princess Gen Harwood, Hayden Panettiere also recorded a song for the film. "I sing a song at the end credits called ‘I Fly,' and it's on the soundtrack," she said. "I've been in the studio a lot with my voice manager, Valerie Morris, who's phenomenal. I've spent a lot of time on the mic, even recently, and have just been really looking for the type of music that I want to do and looking for the right record company, and everything. It's been exciting. Music has always been a passion of mine. I love music, more than anything. I really love music, just listening to it. Five For Fighting is one of my favorite bands, and I love everything from Alison Krauss to Josh Groban to Faith Hill and Jessica Andrews. It's pretty much a place to be free. Being in the acting business, you're portraying roles that aren't yourself. So, when you get in the studio and you get to sing these songs, you get to put yourself into them."

Panettiere's character is the champion figure skater in training who has already devoted her life to physical preparation, at her mother's encouragement, even force on occasion. Compared to Trachtenberg's brainy character, Panettiere feels she could relate to both girls.

"I think I'm somewhere in the middle. I am more of a laid back girl than Gen is. She's definitely a girly girl, very into her looks. I'm not saying that I'm not, but I definitely like sweat pants and my comfy clothes, my Uggs and my pajamas. But, I like school and I'm pretty good at school. I get A's. I do like science too. I love science. And, I can do math relatively well. I just have a great teacher. When you have a great teacher, then it makes the world. I really didn't like chemistry when I first started it this year. I have to say, I really didn't like it because I was on my own, doing it with the home schooling program, and I was sitting there looking at my book going, ‘This is total mumbo jumbo. I have no idea what they're talking about.' It made no sense. And then, I got a chemist, who is actually my tutor, to come to my house to do school, and he makes things so easy and it's so fun to learn. I do like chemistry now."

She also got to have one of Hollywood's most famous single girls play her mother in the movie, Kim Cattrall. "She's phenomenal. She's amazing. She's the sweetest person. She was just such a love to work with. All I'd ever seen her in was Sex and the City, and so going into it, I didn't really know what to expect. I went into the table reading and she was just amazing. Samantha totally left my mind. It was hard for me to think of her like that anymore. She's such a sweet person and she's really good in this film. She and I have the same birthday, so it was exciting."

Providing the other maternal influence is Joan Cusack. As Casey's mom, she would prefer her daughter to stick with academics. Standing up to Cattrall's character in many scenes, Cusack drew on her own maternal instincts to protect her children.

"I think it comes from that passionate parenting thing where you know what, whatever is going on with your kid, if someone does something to your child, it's beyond beyond," Cusack said. "That's totally unacceptable."

With her own children, Cusack expects to soon be dealing with the balance between study and activities in real life. "That's hard. Can they do both? That's a huge balance, I think, with kids. It's everything, you know, it's social life, it's academics, it's sports. I actually think that having a good sense of themselves is the most important thing, actually kind of more emotional intelligence, because then you can say, ‘Okay, here's a challenge I think you can handle,' and they can go for it freely. Or ‘I see this in you, you're good in this, you're good in that. Do it. Do it and enjoy it,' so it's not a struggle as much, when they have a good sense of themselves, I think. When they don't have that it's hard to do everything, and then you're pushing, and they don't know what they really like."

Ultimately, there are strong parallels between Cusack and Cattrall's characters, both wanting the best for their children but believing in different endgames. "We're both kind of pushing what we think our kids should be like on the kid instead of letting them, bringing out their own potential and what's right for them, sort of crossing that line where you want to shape your kid but you don't want to shape them into you; you want to shape them into them."

Playing the parent in Ice Princess gave Cusack a little bit of insight into her own mothering instincts. "I think it's fun to have work that you can relate to, that you can feel like is meaningful. I mean, I might think that's a thing that a lot of parents do. I see it in my own parenting all the time. I definitely don't want them to be actors, but that would be hard, if my sons wanted to do that. It would be really hard for me, because it's a really tough life, and you wouldn't want to put that on your kid, but if that was what you really wanted to do… I mean, you see it in small ways with they have a friend that they want to play with that is not the best influence, but they really want to play with that person, but there's so much you can shape. You've just got to say, ‘He has so much fun with that kid,' you've got to let him do it. It just kind of reinforces [things that are] good to think about, important to think about, fun to sit and talk about."

Ice Princess opens Friday.