Earlier this week, we saw that many people are excited about "Wii Fit."

Some claimed that it would be a great supplement to their exercise regimen. Others said they would use it to start exercising.

While it's great that people would want to use "Wii Fit" to get in shape, I wanted to see what a personal trainer thought. I was too busy chatting with regular folks to speak with the celebrity trainers at the Central Park event, so I sought someone local to my neighborhood.

I met with Nathan, a certified personal trainer and an employee of the Fifth Avenue Fitness Collective, at my apartment. In the industry for two years, he works individually with private clients and teaches classes to people of all ages, levels and abilities, focusing on general strength and cardio.

We went through the different elements of the game, and he gave me an assessment for each portion. Here's what he thought...

Nathan's "Wii Fit" Age And The Problem with BMI

Since Nathan was a first-time user, he had to start with the Body Test. First he input his height (5'9"), date of birth (he's 27) and how heavy his clothes were. Then the game measured his center of balance. He agreed with the anecdotes about balance -- how health experts saying people's postures have been getting worse due to lack of exercise and weakened muscles, and that an unbalanced lifestyle can lead to fat accumulation and increased risk of developing health problems.

After he entered his data, the game told Nathan his Body Mass Index, or BMI, the measure of a person's weight scaled according to height. Nathan's BMI was at 23.48, which is in the "normal" range according to the game. However, he said that fitness trainers typically don't rely on BMI. "The problem with BMI is that it doesn't take muscle mass into account," he said. "Muscle is more dense than fat, so if you are very muscular, your BMI will be actually higher; people that are more muscular are often listed as overweight or obese even though they clearly have a very low body fat percentage."

Next, Nathan took the basic balance test, a test that determines your "Wii Fit" age by giving a series of five balance tests you must complete in 30 seconds. Taking a bit longer to get his footing, Nathan finished only four out of the five tests. The result? His "Wii Fit" age was 39. His Mii shook his head and slumped over in sadness. Nathan wondered what a fitness age of 39 meant.

"I know 40 year-old body builders and runners that are way more fit than I am," he said. "How can you measure someone's fitness level by having them shift their weight back and forth?" He claimed that even if the number were his actual age or lower, he'd still have issues with the "Wii Fit" age. "Fitness is not based on age, but based on body mass, how much weight one can lift relative to their body weight, cardiovascular endurance, muscular endurance, recovery and resting heart rates and other factors -- all these key factors in fitness are not taken into account."

Nathan also had a comment about a loading screen, which said, "Make sure you warm up before exercising." He suggested that it would've been helpful for "Wii Fit" to also include warm-up exercises, since those that are likely to use "Wii Fit" may not know how to do them properly (if they'd even do them at all). "The way you want to warm up is with a slow controlled movement," he said. "There are many ways to warm up but what you want to do is gradually increase your heart rate for, ideally, around 10 minutes. Otherwise you could over exert yourself."

Yoga, Strength Training, Aerobics and Balance Games

I had Nathan try a few exercises from each of the four different sections. In Yoga, he did Deep Breathing, the Warrior Pose and the Tree. He was able to do them well, and thought the individual Yoga poses were "pretty cool." However, he maintained that he was not a yoga expert, and said that yoga has many incarnations. He told me that "Wii Fit" seems to be based on Hatha yoga, which focuses on certain poses and endurance within those poses.

"The fact that it measures you based on foot pressure is okay, but a bit short-sighted," he said. "There are many ways to balance, and unfortunately most people balance via their feet and calves, and that is not the best way to balance. The best way to balance and build balance strength is to use the core. It seems that the game tries to tell you to do that by 'lengthening your spine,' but that might be vague for people who don't understand it or have never done it before."

Then he tried some strength training (Lunges, Push-ups and Side Planks) and Aerobics (Hula Hoop, Basic Run). While all of the exercises shown were useful, he thought that there should be more specific instructions for how to position one's body. For instance, he said the lunges are "easy to cheat on" because there's no direction for knee placement, and for push-ups, elbow placement will change the focus of the movement; thus, people with shoulder widths wider than the balance board may have a hard time.

Meanwhile, the circular motion of hula hooping is a great exercise for the abs -- if done properly. Though hula hooping is a "fun, good way to get your heart rate up," people should be "careful to use their hips and their back in the circular motion"; otherwise, this can be dangerous for their back. "You need to make sure to rely on your hip and tighten the abs when doing exercises like this,” Nathan said. "Weak abs and overuse of the lower back are two causes of chronic lower back pain."

As for the basic run, if you increase your heart rate into a calorie-burning zone and maintain that heart rate, you effectively burn calories for that amount of time. However, jogging in place has people running on the balls of their feet, which causes the calves to tighten. "It would be great if the game included a heart rate monitor because there is really no way for the game to determine how much work you are doing," he said. "Also, at minimum, make sure you stretch your calves after doing this.”

As for the balance games, Nathan played soccer, ski slalom and the ski jump. "It's really fun -- the games are the best part of this thing!" he said, trying to best his scores in the ski jump multiple times. "I like that Nintendo is trying to get people to move their bodies through games. The highlight of 'Wii Fit' seems to be making exercise fun.”

Overall Assessment

As a gamer and personal trainer, Nathan thinks that it's great that Nintendo is making games that encourage people to exercise. However, he recommends that the best way for people to get fit is to exercise with other people or in a class. "Good trainers can look at you when you are doing a particular exercise and tell you what is good and what needs to be changed so that you don’t hurt yourself or do something counterproductive," he said. "It's almost just as bad to exercise improperly, than to not exercise at all."

Ultimately "Wii Fit" is not the all-encompassing fitness package that people might think it is. "Fitness isn't just about these things in the game, but it's about proper lifestyle, proper diet, stretching," he said. "I don't think I would recommend this as someone's sole way of getting fit, but I think that this is definitely a way to pique people's interest -- getting people to transition from sitting on the couch to being interested in exercise. That being said, I think that ‘Wii Fit’ is a great way to start exercising without the pressure of a gym or class setting; people just need to make sure that they are doing things correctly and safely."