There are a number of companies attempting to disrupt personal fitness using mobile apps to provide an engaging user experience that motivates and informs. One that definitely stands out is Skimble, which has just recently passed the 2 million download milestone and, impressively, has already achieved profitability as a bootstrapped startup.

Skimble was founded out of the idea that people want advice and motivation to help them meet their fitness goals, and many people would love to be able to hire personal trainers to tell them what exercises will be most effective. Skimble was a member of the original Rock Health class and their success is absolutely no fluke.

I have had the pleasure of interacting with a lot of entrepreneurs in the digital health space and I can say without hesitation that Maria Ly and her team at Skimble are among the best of the best.  Check out our interview with Maria Ly below and see the video of her recent TEDxUW talk.

Skimble is really two different applications that compliment each other, (1) the Skimble Workout Trainer and (2) the Skimble Sports Tracker, both of which are available for free on both Android and iOS. The Skimble Workout Trainer features complete workout regimens for fitness enthusiasts and athletes, with a number of programs available for free and many more available for purchase at a modest fee.

The workouts typically cost between $5 and $15, which the company is hoping will be seen by users as an attractive alternative to the $80+ it can cost to hire a professional personal trainer at a gym. Currently, the app includes thousands of exercise routines and will soon include hundreds of videos to go along with the current instructional audio clips and stop-motion photos. Users can custom design their own workout routines using an easy to navigate database of exercises and complementary audio clips.

The GPS Sports Tracker allows users to automatically track 45 different physical activities and earn points based on the intensity and duration of that activity in a competition with other users. Sports that can be tracked using the app include sky diving, slack lining, climbing, yoga, ping pong, horseback riding and skateboarding.

The company has recently struck a deal with Harvard Medical School to create the “Harvard Health Gym Coach” to create plans designed by Harvard medical professionals, a deal the company hopes to use as a model for future partnerships with similarly distinguished institutions which will be a significant competitive advantage.According to co-founder Mary Ly, formerly a member of the International Product Group at Google, Skimble is both bootstrapped and profitable and has encouraging user metrics, such as 50 percent download-to-sign-up conversion rate, 30 percent 30-day retention rates, and 20 min in-app session times.

One key reason why the company is profitable is the fact that they are so effective at monetizing each user, whether it be with ads, in app purchases or upgrade to the pro version of the product. Skimble’s other co-founder is Gabe Vanrenren, previously co-founder of Flurry, which specializes in helping mobile app developers maximize engagement with their users. This is probably one of the key reasons why Skimble has been able to achieve such positive user metrics and their 2 millionth download in early 2012, making them one of the top health apps in the App Store.

Skimble’s apps bring me back to the days when ESPN would have personal fitness gurus during the daytime (before SportsCenter essentially became a 24-hour news program) and each would have their own exercise products and self-branded machines. I had thought these personal fitness brands would be forever relegated to the late night infomercials and NBC’s The Biggest Loser. That is until I saw Skimble and it became clear they are offering personal trainers a new media platform to brand themselves and distribute their products via mobile devices.

The quantified self movement has certainly seemed to gather some steam in recent months as more and more people begin experimenting with various methods of tracking oneself to generate meaningful and useful data.

Healthrageous (@healthrageous) is one company betting that this movement will soon become big business.

The company was founded by physicians associated with Harvard Medical School following a 2008 study by researchers at the Center for Connected Health, a division of Partners HealthCare, which tracked individuals with hypertension who worked for the computing company EMC. Employees were asked to keep track of their blood pressure at home and participants received feedback on their progress.

The program proved quite successful at lowering blood pressure. Not only did an independent auditor of the study suggest that some EMC staffers would avoid heart attacks and strokes as a result of the feedback they received, the program was also estimated to have a 3:1 financial return.

An example of the machine learning technology, referenced several times by, Mr Zobol, would be the platform asking an individual whether they want to lower their blood pressure through diet and exercise or with the help of medication. Users who respond that they prefer to do it naturally can be informed that people who exceed 10,000 steps per day have a greater likelihood of bringing systolic blood pressure down to healthy levels.

Users would then try to steadily increase the amount they walk and wear pedometers to assess whether they are succeeding–with the software providing encouragement in a variety of different ways.

According to a Technology Review profile of the company, Healthrageous already has 1,600 users generating $500,000 in annual revenue across at least seven institutional clients. The company is poised to release the platform to the general public by the end of 2012.

Below you can read my interview with Greg Zobel, VP of Business Development for the 18 month old company, who explains to me a little bit about their vision for the quantified self business model.

BTE: What is the inspiration behind Healthrageous?

Greg Zobel: Essentially, to find a way to use machine learning to make meaningful sense of the data being collected from all the various sensor devices you see around the floor here.

BTE: Which devices are currently part of your ecosystem?

Greg Zobel: We are very device agnostic. The devices that are currently plugged in are mostly fitness or A&E devices, but literally any wireless device can plug into this platform.

BTE: What is the business model for this platform?

Greg Zobel: Essentially, this is a machine learning platform that is marketed through various channels to consumers. Not directly to consumers, but through channels, for instance health plans, employers, and what we call “health adjacencies”, such as the large weight loss programs around the country (i.e. Jenny Craig). Anybody really that has an engagement problem, that needs to hold onto their clients and become more engaged with their customers.

BTE: So who is the client in this mixture? Who is paying you?

Greg Zobel: Typically, or at the moment, clients are health plans who is embedding our product either into their wellness offering or into their disease and care management offering. I don’t know how much you know about what is going on in that space right now, but there are a lot of things like like high deductible health plans who are using our platform to reduce premiums for those who are on the healthier side.

BTE: So lower premiums for people who are active, and you guys are contracted to monitor and support the data?

Greg Zobel: Right, and we do it objectively, which is very important.

BTE: So I assume there is a consumer web app that gives users access to their data?

Greg Zobel: Correct. Virtually every person using the system is a consumer, like you or I, and they have access to their data both through the web and via all three mobile platforms. We use wearable wireless devices to capture the data and smartphone apps provide the interface to the consumer.

BTE: So very little computing actually takes place on the smartphone? It serves as more of an application interface for the cloud-based data captured by wearable sensors?

Greg Zobel: Correct. We are a machine learning platform, taking in massive amounts of information, asking users questions to conduct a health risk assessment, building a profile of each user and then pushing messages back out to you as the user which we know are relevant to you and will help you improve whatever aspect of your health you are working on. Its like the Pandora or Netflix for health care.

BTE: How many team members do you have today?

Greg Zobel: Currently, Healthrageous has 20 folks working in our Boston headquarters. When you lift up the veil its basically a bunch of MIT engineers, Harvard behavioral scientists and a few business development specialists like myself.

From a customer standpoint, we have six self insured employers on the platform, and our landscape changes very significantly next year because we are in the process of implementing three very large Blue Cross Blue Shield plans in California, Pennsylvania and another in the middle of the country, so it is going to be a big year for us.

BTE: Have you raised venture funding or are you self-funded?

Greg Zobel: We were officially “born” as a venture backed firm in June 2010. We have three major venture backers, North Ridge, Long River and Egan-Managed Capital, and that was our Series A round. We are in the process of raising a Series B round right now.

BTE: What is the next big step for Healthrageous? Can you share any of your business development plans as the business development director?

Greg Zobel: Well, the platform itself is designed to be stand alone–or in other words–the intel behind these other devices and services, so we are working with a lot of the big telco’s you see on the floor here who are looking for a way to figure out how to absorb the massive amounts of patient data that can be collected and make sense out of the data for the consumer. That is the layer we provide.

BTE: So you envision being able to provide the service to the consumer free of charge indefinitely?

Greg Zobel: Correct.

Rock Health (@Rock_Health) has opened applications for a second class of companies to join its San Francisco-based incubator. The program begins in the middle of January and concludes with demo day in the middle of June. Selected applicants will each receive:

• $20K startup grant
• Expert medical support from Mayo Clinic, Harvard, UCSF and Cincinnati Children’s Hospital
• Mentorship and weekly workshops from experts in design, health policy, lean startup methodology, financing, etc…
• Office space in San Francisco
• Office hours with startup counsel
• Design workshop with Cooper Design
• Support from in-house staff

Rock Health is the brainchild of Halle Tecco, who following her first year at Harvard Business School, got an internship at Apple in Cupertino, CA evaluating mobile apps for the health and medical category of the iTunes App Store. “I was on the phone all day with big hospitals and healthcare organizations who didn’t put the love into their apps,” she told Xconomy San Francisco in an impressive profile of the new digital incubator. “They were building things with a check-box strategy, and in my opinion they didn’t have much creativity or innovation”.

Tecco founded Rock Health as a non-profit incubator exclusively tailored to startups working on web- and mobile-based healthcare technologies, and has brought on board major partners including the Mayo Clinic, Harvard Medical School, Microsoft, and Qualcomm. She launched the project at SXSW just this past March and already has nearly one full session in the bag and another on the doorstep – quite an impressive 2011 for Ms. Tecco and her team.

More than 350 companies submitted applications for the inaugural Rock Health class this past June, of which the following were selected:

• Pipette: Smartphone and tablet apps that give doctors easy-to-read reports on their patients’ health progress, featuring automatic identification of critical patterns and outliers.

• WeSprout: An online community designed to help parents find resources for decision making about their children’s healthcare.

• Skimble: Healthcare fitness apps for iPhone, iPad and Android devices, including two successful titles, Workout Trainer and GPS Sports Tracker.

• Omada Health: An Ideo spinoff using social networking principles to aid patients at risk for developing diabetes through sharing of data from connected-health devices.

• Health In Reach: A transparent marketplace where patients without employer-sponsored healthcare plans can evaluate doctors and dentists based on their experience, reputation, and prices, and obtain group discount rates.

• Genomera: Crowdsourcing platform for consumer-managed open health studies.

• CellScope: Smartphone camera attachments for at-home diagnosis of ear infections in children.

• BrainBot: Brain monitoring technology for individuals, designed to help with stress management, meditation, or attention problems.

Applicants can fill out the impressively simple application form on the Rock Health website which are due by November 14th. Also, check out the incubator’s blog to find a complete guide for potential applicants.

There has been a flurry of H1N1 applications, and they are all a bit hard to differentiate. There is a notable app that was recently released. The app, HMSMobile Swine Flu Center, was developed by Harvard Medical School and costs $1.99. This is the first Swine Flu App in the App Store with a big-time medical name behind it. The app itself has built in videos explaining H1N1 and other related topics. It also has the "outbreaks near me" feature that most of the swine flu applications have. Of note, the app has a "business add on" feature, that provides advice to businesses on how to prepare for outbreaks in the workplace.

There is a nice video of the application on the Harvard website that can be found here:

The iTunes link to the application can be found here.