|Women's cross-country skiing|
|2006 Turin||Individual sprint|
|2005 Oberstdorf||Team sprint|
Sidko won a bronze medal in the Individual Sprint at the 2006 Winter Olympics in Turin. She also won a bronze in the Team sprint (with Yuliya Chepalova) at the 2005 FIS Nordic World Ski Championships in Oberstdorf and had her best individual finish of 12th in the Individual sprint in 2003. Sidko has nineteen wins at various levels in distances in up to 10 km since 2002. She took the 2007-08 season off due to pregnancy but returned for the 2008-09 season.
Sidko was banned from competing at the 2010 Vancouver Olympics for breaking anti-doping rules. She had tested positive for EPO at a race in Krasnogorsk 26 December 2009 and was subsequently banned from competing in the sport for two years.
- "Doping puts end to Olympic dream for 30 athletes". Russia Today. Archived from the original on 15 February 2010. Retrieved 15 February 2009.
- Topher Sabot: Russian Alena Sidko Tests Positive for EPO, fasterskier.com, 20 January 2010