Fitness trackers on mobiles helped people stay healthy amid pandemic lockdowns but the devices also added stress with information overload about COVID-19, a study has found.

An article published in the latest issue of the journal PLOS Digital Health examines how technology was used around the world at the height of the pandemic between July and September 2020.

An international team, led by University of Sydney PhD candidate Huong Ly Tong, surveyed more than 500 people from 32 countries and found 83 per cent used apps to stay active.

"The study found people who used mobile apps were more likely to be more active," Ms Tong said.

"This demonstrates that technology can play an important role in helping to promote healthy behaviours, even during the unique circumstances of the pandemic."

Around a third of people surveyed in the study, mostly Australians, said apps also came in handy to manage their mental health.

But the authors also found apps and social media functioned as a "double-edged sword".

"On one hand, these apps helped people maintain a sense of normalcy, to stay active and connected," said University of Sydney senior researcher Dr Liliana Laranjo.

"But at times, they also had a negative emotional impact when people felt exposed to too much information about COVID-19 online or when they felt they weren't meeting their fitness goals on trackers."

Australia recorded 64 deaths across its two most-populous states in Saturday's reported figures, and almost 9500 new cases.

LATEST 24-HOUR COVID-19 DATA:

Victoria: 3354 cases, 30 deaths, 471 in hospital with 30 in ICU

NSW: 6116 cases, 34 deaths, 1908 in hospital with 56 in ICU

Queensland: 2647 cases, 20 deaths, 394 in hospital with 17 in ICU

WA: 1624 cases, seven deaths, 237 in hospital with seven in ICU

SA: 851 cases, five deaths, 263 in hospital with nine in ICU

Tasmania: 323 cases, one death, 56 in hospital with three in ICU

ACT: 252 cases, no deaths, 121 in hospital with four in ICU

NT: 134 cases, no deaths, 27 in hospital with none in ICU