Fitbit is updating two older devices, the 2013 Flex and the 2014 Charge, mostly to bring them in line with what newer devices and rivals offer. In addition, the company wants to help you exercise more by making you think you're hiking famous trails, with the new "Adventures" motivational feature that will be available to all Fitbit users through a free app update Monday.

The feature tracks the distance you've walked or run and maps it against actual trails, starting with three at Yosemite National Park in California. The app will unlock badge-like images of trail landmarks as you progress. Other rewards include "fun facts" and health tips along the way. Fitbit will add other destinations, including the ability to "run" the course of the New York City Marathon.

One of Fitbit's most popular features has been its ability to let friends and family compare steps they've taken throughout the day. Fitbit says those who participate in such challenges tend to take 30 percent more steps. The company says Adventures is designed to offer similar challenges even if people haven't assembled real-life groups.

Fitbit is also updating the 2013 Flex and the 2014 Charge. Charge 2 and Flex 2 track your most important health and fitness stats, with new looks. Both products are available globally today for presale, with retail availability starting this fall:

• Fitbit Charge 2: In addition to PurePulse heart rate tracking, it now features new health and fitness tools, the smart notifications, and a new design with a larger display and interchangeable bands that let you go from a workout to a night out.
• Fitbit Flex 2: Fitbit?s ultra-slim, swim-proof fitness wristband features a removable tracker that transforms with classic bands, elegant bangles or pendants, allowing you to track all-day activity, exercise and sleep.

Top features of Charge 2 include:

• PurePulse: Continuous heart rate tracking makes it easier to maximize workouts. Charge 2 advances health and fitness tracking with two new features:
  • Get a snapshot of your cardio fitness level: Automatically find out how fit you are with a personalized cardio fitness level and score, based on your estimated VO2 Max, that are calculated using your user profile, heart rate and exercise data. Plus, get guidance to take action and improve your score over time by increasing exercise frequency, intensity, or by reaching a healthier weight.
• Relax with guided breathing sessions: Charge 2 offers a relaxing experience that calms your body through personalized deep-breathing sessions called "Relax". The beat-to-beat changes in your heart rate determine your personalized breathing rate for each experience. Two- and five-minute sessions display real-time heart rate visualizations, animations and vibrational cues to help you align each inhale and exhale with the guide, and find moments of calm throughout your day.
• Get real-time, actionable exercise stats right on the display.
• Multi-sport modes: Track specific workouts like runs, bike rides, weights, yoga and more, plus get post-exercise summaries and a detailed report of your activity in the Fitbit app.
• Connected GPS: Links your fitness wristband with the GPS in your smartphone to provide even more precise and actionable real-time stats, like pace and distance when you?re running, while recording a map of your route in the app.
• Interval workout mode: Guides you in alternating periods of high-intensity exercise and recovery to maximize workouts like circuit training so you can stay focused on your workout.
• Smarter, easier all-day tracking: Sensors make tracking your whole day effortless by automatically capturing all-day activity and sleep. SmartTrack automatic exercise recognition records everyday activities like walking, running, elliptical, and more with ease. Reminders to Move motivate you to stay active throughout the day.
• New design: The modular design and easy-to-read tap-sensitive display is four times larger than Charge HR, letting you personalize a look that fits your style with interchangeable bands and clock faces.

Flex 2

Fitbit has enhanced Fitbit Flex, into an ultra-slim, swim-proof fitness wristband. With smarter exercise features, Flex 2 tracks your fitness and provides friendly motivation.

Top features include:

• Ultra-slim design: Now 30% smaller, Flex 2 features a removable tracker and interchangeable slim, classic fitness bands in seven colors.
• Accessory options: Transform and customize Flex 2 in a variety of Fitbit-designed bracelets and pendants to best suit your style or activity. Choose from a range of mirror-finish bangles in silver stainless steel, and 22k-plated gold or rose gold stainless steel, or lariat-style necklaces in silver stainless steel or 22k-plated gold stainless steel.
• Swim-proof and automatic swim tracking: As Fitbit?s first swim-proof wristband, Flex 2 is water resistant up to 50 meters, and it automatically tracks your pool swims including laps, duration and calories burned in the Fitbit App.
• Effortless and automatic: Track your most important health and fitness stats, plus:
  • SmartTrack automatic exercise tracking recognizes select workouts (walks, runs, rides, elliptical, sports, aerobic workouts, and now swims).
  • Reminders to Move help you stay active with friendly reminders to reach mini hourly step goals and reduce stationary time.
  • Personalized weekly exercise goals.
  • Smarter: A LED display uses color-coded lights to show progress toward your daily goal, and keeps you connected with call and text notifications

Charge 2 and Flex 2 are available for presale today on Fitbit.com and tomorrow at major North American retailers online, including Amazon.com, Best Buy, Brookstone, Dick?s Sporting Goods, Nordstrom, REI, Target and Verizon. Fitbit Charge 2 and Flex 2 will be available globally at other major retailers in September and October, respectively. Prices below are on Fitbit.com, pricing at retailers may vary.

Fitbit Charge 2 ($149.95) tracker with a classic fitness band in black, blue, plum or teal Classic fitness accessory bands in four colors, sold separately ($29.95) Luxe premium leather accessory bands in blush pink, brown and indigo ($69.95)
Special edition series in gunmetal and rose gold coming soon ($179.95)

Fitbit Flex 2 ($99.95) tracker with a classic fitness band in black, lavender, magenta or navy Classic fitness accessory bands in seven on-trend shades of black, blush pink, gray, lavender, magenta, navy and yellow, coming soon and sold separately ($14.95)
Classic 3-pack fitness accessory band hues in Pink (blush pink, lavender and magenta) and Sport (gray, navy and yellow) coming soon ($29.95)
Bangle accessory in gold, rose gold ($99.95) and silver stainless steel ($89.95) Pendant accessory in gold ($99.95) and silver stainless steel ($79.95)