While 70 million wearables will ship in 2014, that figure will fall to 68 million next year.
That is because the entry of smartwatches into the marketplace will have overlap in functionality.
But the figure is set to rise again in 2016 because lower cost machines will be available along with a variety of different designs.
The push to get people to use fitness wearables is being funded by a number of industry giants including Qualcomm, Apple, Google, Samsung, Microsoft, Nike and Intel.
Gartner sys the five main form factors are smart wristbands, sports watches, other fitness monitors, heart rate monitor chest straps and so called smart clothes.
This last category has the biggest potential for growth, according to Gartner and so-called “smart shirts” are no becoming available. The research firm didn’t say whether the next step will be “smart pants”.
While smartwatches will come in many different price range, those costing $150 or over are likely to include accelerometers and gyroscopes but unlike health wristbands will have to tell the time and have the capacity to send and receive texts.