Dee ihe na-aga n'ihu maka paragraf a - Nwa amaala Needham, Massachusetts, Arnold gara ma kpọọ hockey ụlọ akwụkwọ sekọndrị na Noble na Greenough School na mmemme Boston Junior Bruins tupu ya esonye na USA Hockey National Team Development Program maka oge 2009<unk>10. Na U-17, Arnold bụ onye isi otu egwuregwu ahọpụtara nke sonyere na asọmpi mba ise na Slovakia; akpọrọ ya onye ọkpụkpọ kachasị baa uru na asọmpi ahụ. Na 2010 IIHF World U18 Championships, Arnold dekọtara isi ihe atọ n'egwuregwu isii dịka National Team Development Program, na-anọchite anya United States, meriri nrite ọla edo. Na 2010 National Hockey League (NHL) Entry Draft
, A họpụtara Arnold na agba nke anọ, nke 108 n'ozuzu, site na Calgary Flames.