At the 2001 &lt;a href="IAAF%20World%20Youth%20Championships%20in%20Athletics"&gt;IAAF/Westel World Youth Championships&lt;/a&gt;, Cuddihy qualified for the final of the 400 metres by finishing second in her heat with a time of 54.16, a season's best. On 14 July, Cuddihy finished fifth in the final at the World Youth Championships. The following year at the &lt;a href="IAAF%20World%20Junior%20Championships%20in%20Athletics"&gt;IAAF/Coca-Cola World Junior Championships&lt;/a&gt; in Kingston, Jamaica, Cuddihy finished sixth in the final. On 12 June 2003, at a European GP meeting in Riga, Latvia, Cuddihy broke the junior Irish national record in the 400 metres with a time of 53.21 seconds. At the NCAA Championships in Sacramento, California in mid-June 2003, Cuddihy came second with a time of 53.85 seconds. The following month, she won a silver medal at the 2003 European Athletics Junior Championships in the 400 metres.