UK Anti-Doping (UKAD) has announced 1,406 tests were conducted from July 1 to September 30 as competitive sport returned to the country following the first nationwide lockdown.
UKAD said this represents a significant increase of tests from the previous quarter, when sporting activity was effectively halted amid the coronavirus pandemic.
The agency defines a test as any attempt to test an athlete in a single sample collection session, with multiple samples - blood and/or urine – collected.
If the athlete is not located or unavailable for testing, this is defined as one unsuccessful test attempt, regardless of the number of planned samples to be collected from that athlete.
A total of 1,307 tests were successfully carried out, while 99 were unsuccessful.
Four adverse analytical findings were reported during the second quarter of the year.
A total of 1,532 have been conducted by UKAD this year, as part of the domestic and international anti-doping testing programme.
Overall 1,431 were successful.
"I'm very proud of the work our testing team who have delivered a substantial increase to our testing programme in very challenging circumstances," said UKAD director of operations Pat Myhill.
"These figures should reassure the public as they show that we have been able to track the return of sport with a robust and thorough testing programme.
"As we know the significant COVID-19 restrictions in place are still affecting us all, and this is no different to operating a testing programme.
"The different Government and local authority restrictions in place across the UK require us to adapt our processes to meet our testing requirements across the regions and nations.
"Testing is just one part of a successful anti-doping programme and our education programme has educated thousands of athletes since March, and we continue to process and act on intelligence reports.”
UKAD said the highest numbers of tests were in football, cricket, rugby union and league, and athletics.
The Football Association conducted 362 tests, followed by the England and Wales Cricket Board on 171.
The Rugby Football Union and the Rugby Football League conducted 150 and 146 tests respectively, while the figure for UK Athletics was 92.
UKAD said the quarterly report also includes tests conducted on behalf of UKAD on UK athletes based overseas.
Athletes competing internationally could also have been tested by their respective International Federation.