Approximately 1.6 million smartwatches were shipped in the second half of 2013, and over 17 million total wristworn trackers are expected to ship in 2014, according to market research firm Canalys.

Fitbit shipped the most wearable bands (58 percent market share), which Canalys suggested could be because Fitbit launched its Flex and Force bands in May and October 2013 respectively. Jawbone had the second largest market share with 21 percent. After Jawbone, Canalys found Nike had 14 percent and the other fitness bands made up the last 8 percent.

In the smartwatch category, Samsung Galaxy Gear had the largest market share, 54 percent, and Sony had the second most shipments, 19 percent. Pebble, a fitness-focused smartwatch was just under Sony's shipment numbers, at 16 percent. All other smartwatches made up the last 11 percent.

"Basic band vendors have greater wearable expertise and have shipped greater numbers to date, but smart bands are already growing faster," Chris Jones, VP and Principal Analyst at Canalys said in a statement. "Increasingly, smart bands will adopt basic band features as the two categories converge."

Some of this convergence might already be evident. Fitbit's newest band, the Force, has more display features than its predecessor, Fitbit Flex. The biggest convergence could be Apple's rumored iWatch, which will at least have some fitness features, given the company's recent hiring spree.

Canalys also predicts wearable bands will represent a large opportunity in the medical and wellness segment and in 2014, the smart band segment is estimated to reach 8 million. Shipments will grow to over 23 million units by 2015, and over 45 million by 2017.

"The wearable band market is really about the consumerization of health," Canalys Analyst Daniel Matte said. "There will be exciting innovations that disrupt the medical industry this year, and with the increased awareness about personal wellbeing they will bring to users, having a computer on your wrist will become increasingly common."

Another market research company, NPD Group, reported that Fitbit, Jawbone, and Nike made up 97 percent of all smartphone-enabled activity trackers sold at brick-and-mortar stores or through big ecommerce sites. NPD's data was calculated from the entire 2013 year, beginning in January 2013 and ending in early January 2014.

According to NPD, Fitbit’s devices accounted for 68 percent of devices sold; Jawbone UP sales accounted for 19 percent of all devices sold; and Nike FuelBand sales made up 10 percent of sales. All other activity tracking devices together accounted for the remaining 3 percent of sales.