The explosions targeted the "Race of Hope" annual marathon in Buea, in the Southwest region, 70 kilometres (43 miles) west of the country's economic capital Douala.
Mark Kangogo, 33, has been provisionally suspended after tests showed the presence of two prohibited substances in his system.
Chinese authorities have been racing to contain virus infections via mass testing of residents and targeted lockdowns.
Benson Kipruto and Diana Kipyogei completed a Kenyan clean sweep in the men's and women's races at the pandemic-delayed Boston Marathon to pick up their first major titles.
Twenty-six-year-old Ruth Chepngetich clocked 21 kilometres run in 1 hour, 4 minutes and 2 seconds to break the world record by 29 seconds in the women's category.
Hundreds of sporting events disappeared around the world during 2020 in the midst of a raging Covid-19 pandemic.
Collin Allin, 41, and wife Hilda covered the 42.2-kilometre distance by running more than 2,100 laps of their 20-metre long balcony from dawn on Saturday.
Controversy over Nike's hyper-advanced Vaporfly shoes that some say give runners an unfair advantage boosts performance of some of the sportswear giants' rivals.
Peter Snell, who is regarded as one of the greatest middle-distance runners of all-time, won the 800 meters at the 1960 Rome Olympics aged 21, and the 800-1,500 double at the 1964 Tokyo Games.
About 5,000 runners competed in the 42-kilometre marathon which started on the Asian side of Istanbul’s July 15 Martyrs’ Bridge and finished in the historic Sultanahmet Square on the city’s European side.
The feat by Eliud Kipchoge is the largest single improvement on the marathon world record since Derek Clayton improved the mark by 2:23 in 1967.
Kenya-born Rose Chelimo was in the lead by the 30-kilometre mark and won in 2 hours, 34 minutes and 51 seconds.
Subscribe to our Youtube channel for all latest in-depth, on the ground reporting from around the world.
Copyright © 2023 TRT World.