Wearable health technology first started in hospitals as a way to help people with injuries heal faster. Now, the trend has gone mainstream and pro-active; one in five online adults uses a wearable device, and the majority of those devices are health-related, according to Forrester Research.

"Americans are using a variety of wearable devices to help them reach their wellness goals," says Mike Nohilly, an expert in wearable technology for Slendertone. "Once, people would have needed a doctor's visit to find out key wellness numbers like BMI or blood pressure, or needed gym equipment to monitor their heart rates while exercising. Wearable devices allow them to do all those things, and even tone specific muscle groups, at their own convenience."

Here are five wearable health devices and how you can use them to help build fitness and better health whether at work or at home:

Fitness trackers

Stock photo

If it seems like everyone is wearing some kind of fitness tracker, you're not imagining it. The top wearable of 2015 was a fitness tracker that shipped more than 21 million units and represented nearly 38 percent of the wearables market, according to International Data Corporation. Fitness trackers allow wearers to monitor key health indicators, such as heart rate or calories burned. You can also use them to set and track exercise goals, such as walking a certain number of steps per day, or monitor your heart rate while exercising to ensure you reach a target zone.

Pain relief braces

Worn like traditional braces, smart braces use neurostimulation sensors, built into the fabric, to ease pain with low-level electrical impulses. Wearers rely on the bands to help relieve joint pain from chronic conditions like arthritis. Some come with a smartphone app that allows you to track usage and sleep patterns.

Ab toners

Instead of spending hours in the gym doing crunches, you can enhance your workout by wearing a piece of technology that works to strengthen, firm and tone your abs. The Slendertone Connect Abs wearable belt and others use electrical muscle stimulation (EMS) to stimulate the major abdominal muscles, and can be worn and used at any time -- even under your clothes. Users report visible results in six to eight weeks when used at least five days per week for 30 minutes. You can control this FDA-cleared device through an app on Android or Apple smartphones, and choose one of five goal-driven programs, from essential toning to post-natal and even advanced toning. The app also tracks and shares data on your progress.

Sleep trackers

Getting the right amount of sleep is critical for overall health, so sleep trackers have gained popularity as aids to help people get better rest. Many types are available and some are wearable. Sleep trackers monitor such sleep metrics as REM phases, how long per night you spend in light sleep versus deep sleep, wake times, how quickly you fall asleep, what time you sleep each night and more.

UV detectors

An emerging form of wearable technology, UV detectors monitor skin exposure to harmful ultraviolet radiation -- the portion of sunlight that causes sunburn, tanning and skin cancer. Multiple versions are under development, and one commercially available detector is a small patch that you wear on your skin and then scan using your smartphone that's been equipped with a special app. The app allows you to read the information recorded in the patch so you know your UV exposure, and offers tips for sun safety, including what level SPF sunscreen you should wear.

"Many health care and tech industry watchers say the wearable health care device trend is really just getting started," Nohilly says. "Technology has great potential to help make it easier than ever to achieve our health and fitness goals, whether we want to get a better night's rest, improving cardiovascular health or get toned abs."