What used to be a humble device used to make phone calls and maybe send a text message or two has morphed into an all-encompassing communication and multi-media smart phone capable of sending e-mails, searching the Internet, taking photos and playing music and videos.

A phone weighing less than five ounces literally contains our whole world.

Today, we find ourselves in the era of apps: applications designed to make our lives even simpler by allowing us to tweet, check stocks or even get directions in a matter of seconds without an Internet connection. The plethora of mobile apps available to smart phone users today totals tens of thousands.

We have become an “app-savvy” nation. A recent study by GetJar, the world’s second largest app store, shows that the market for mobile device software is on track to reach $17.5 billion in the next three years. Downloads of mobile apps will leap from just over 7 billion in 2009 to nearly 50 billion downloads in 2012.

In the hustle and bustle of our increasingly busy lives, wouldn’t it be great if we could bring fitness to our fingertips? maybe it’s an app that can help us lose weight, train for a race or find nutrition info on the foods we eat.

Yes, there are apps for that.

Thanks to a convenient marriage of the smart phone and fitness worlds, we now have mobile fitness applications. Today’s health and fitness applications have been developed to meet the needs of people seeking immediate information about new workouts, calories burned during exercise, nutrition advice or even exercise pointers — all designed to appeal to both those new to exercise and the devoted fitness enthusiast.

Many apps act as a virtual fitness partner by tracking your progress or even reminding you to work out. It feels like only yesterday I was marveling at the idea of a TV on a treadmill!

“Accountability” is what Joe Decker, a local fitness trainer recognized as the world’s fittest man by Guinness World Records, says is the biggest selling point for health and fitness apps.

“Granted, it’s not a person telling you what to do, but with an app, it grades you, reminds you and keeps you accountable; there’s no lying to yourself or cutting corners,” said Decker, who was given his title after breaking the Guinness World Record’s 24-hour physical fitness challenge in 2000. “It’s easy to lie to other people, but you can’t lie to an application. It’s like someone day in and day out is checking up on you.”

Decker is the fitness contributor to the iPhone application “Body and Mind Connection” by B Healthy U, a publisher of mobile applications that help individuals discover, rate and adjust their day-to-day activities to aid in increasing their energy and managing stress to lead a healthier life.

One feature of the application allows you to grade your sleep pattern by inputting factors such as diet and exercise to determine if there are any correlations as to why you may have trouble sleeping. The app also offers daily fitness and diet tips from Decker and Dr. David Katz, director of the Yale University Prevention Research Center.

As an avid exerciser and iPhone user, I took the chance to review the top ranking health and fitness iPhone and iPod Touch applications, both paid and free. here are eight great apps that tickled my fitness fancy.

iFitness (paid) — A top selling iPhone fitness application, iFitness costs $1.99 and allows users to electronically plan and log their own pre-selected or customized workouts. Touted as the “personal trainer” application, users can select exercises by muscle group, including some that can be done at home with minimal equipment; get tips on proper form and find tailored workout routines to address particular problem areas with photos and instructions for more than 130 exercises. The pre-set routines are ideal for beginners who may need more information on what muscles they are working and how many sets and repetitions to do for each exercise.

Tap & Track (paid) — Keeping a food diary can be burdensome, but Tap & Track conveniently allows you to log your daily calorie intake, find calories burned during exercise and set a diet plan to help you reach your goal weight. Tap & Track starts by calculating your Basal Metabolic Rate (BMR) to determine your body’s daily caloric needs based on your gender, age, weight and height. For $3.99, the weight management app offers an extensive nutrition database of 80,000 food items verified by nutrition experts, and nutritional information for more than 400 restaurants. Remember to consult your doctor before starting any weight-loss plan.

iTreadmill Pedometer (paid) — iTreadmill is a pedometer-based application that tracks your distance, steps and speed. Simply attach your iPhone or iPod Touch to your arm band, pocket, purse or belt clip, and a sensor in the app monitors your steps by tracking the up and down motion of your body — just don’t make your arm swings too big or you’ll throw the gauge off! if you are running outside and have to stop at a light, the app will automatically stop and restart when you pick up your pace. you can also preset the pace that you want to run or walk and iTreadmill will keep you accountable to that pace. Enter your weight before using the application and it will track average calories burned. At the time of publication, this app was half off at $.99.

Couch to 5K (paid) — The most popular beginner’s running app, Couch to 5K (or C25K for short) is the virtual equivalent of a human training partner. Many people who attempt to run get discouraged mainly because they go out too hard and too fast. C25K helps users of all abilities to get in shape to run three miles in two months, as the app developer claims, starting with a more encouraging walking and jogging regimen. The $2.99 app measures activity by distance or time, whichever is most convenient for the user. To be successful, the app requires users to dedicate 20 to 30 minutes to exercise two or three times a week.

Eat This, Not that! (paid) — Based on the best-selling book by the editor of Men’s Health magazine, the Eat This, Not that! application shows you which foods to swap for healthier options. As the name implies, the app allows users to find thousands of healthy food “swaps” to eat better and lose weight by tracking their caloric intake with a database of more than 23,000 food and menu items. you can also set a weight-loss plan, find calories burned during exercise, learn restaurant survival strategies and build a healthy grocery list by choosing from thousands of graded items.

Six Pack App (free)— This popular free iPhone application serves as a resource to guide you through 100 weight-training, yoga and stretching exercises with more than 400 detailed photo tutorials. Learn how to target specific parts of the body with images outlining which muscles you are working and find tips on what equipment to use to fully work various muscle groups. A “Don’t” tab tells you what not to do when performing an exercise to avoid injury. Bring your phone with you in the gym and use this app to guide you through a total body weight training routine.

101 Yoga Poses (free) — This free app could save you a few bucks on an expensive yoga studio membership by providing a virtual catalog of 101 yoga poses that you can practice anywhere, any time. The app is ideal for beginner yogis who could benefit from high-resolution photos and detailed step-by-step instructions on the correct form for each pose. plus, a countdown timer tells you how long to hold each pose. The only downside is the app comes sans calming music, so try to find a peaceful place to practice if possible.

Weight Watchers Mobile (free) — This popular weight-loss and management program has gone mobile! The Weight Watchers app allows faithful Weight Watchers followers to track the “points” value of a variety of foods and restaurant menu items as well as find the best options for what to eat. Mobile Weight Watchers subscribers can also find a list of activities for their fitness level and track the “points” value of those activities. As a plus, everything subscribers do on this application will be seamlessly reflected in their online Weight Watchers account.

A mobile fitness application may help you jump-start an exercise routine and keep you on a healthy track for life, but Decker still encourages people to get back to the basics for exercise.

“When it comes to changing lives, people still need to get out to work out and interact together,” said Decker, who founded Gut Check Fitness boot camp in San Diego with his wife, Nicole. “We can’t have our whole lives exist inside that phone.”

That being said, there are people who may have trouble getting out and connecting with a group, so an application can act as a stepping stone to fitness and keep people in line,” he added.

This list only breaks the surface of the many health and fitness applications available. if you are hungry for more healthy apps, click here to see more “Apps for Working Out” in the iPhone app store.

Remember to always consult a doctor before starting an exercise regimen, and take into consideration that no matter how cutting-edge an application may seem, it should not replace a qualified personal trainer who can monitor your form in person and develop an exercise plan uniquely tailored to you.

Cassie Piercey is an SDNN contributing writer.