Sales of Fitbit's fitness trackers surged in the second quarter, while Apple's Apple Watch saw its market share decline, according to IDC.
Shipments of basic wearable devices, defined as simple fitness bands with no third-party applications, climbed 48 percent above last year's levels.
Meanwhile, smart wearable devices like the Apple Watch are struggling. Overall, shipments of smart wearables declined 27.2 percent year-over-year. Things look even worse when you break out Apple Watch shipments, which plunged nearly 58 percent compared to the same quarter last year.
Apple hasn't released a new Apple Watch since the device was first unveiled last year. As IDC points out, the lack of innovation has prompted many would-be buyers to hold out for a newer model, or just opt for another smartwatch brand entirely.
"There is plenty of curiosity about what smart wearables -- particularly smartwatches -- can do, but they have yet to convince users that they are a must-have item," said Ramon Llamas, research manager for wearables at IDC. "The good news is that smart wearables are still in their initial stages and vendors are slowly making strides to improve them. But this also means that it will be a slow transition from basic wearables to smart wearables."
Coincidentally, the research comes a day before Apple holds a planned media event in San Francisco, where it's expected to unveil a revamped Apple Watch, along with its latest generation iPhone.
Overall, Fitbit's "dominance remains unchallenged" in the basic wearables segment, IDC says. The research firm found that total shipments of wearable devices increased more than 26 percent between April and June this year. Fitbit leads as the top wearable device vendor, with Xiaomi, Apple, Garmin, and Lifesense rounding out the top five, respectively.