Pedzisa mutsara unotevera: Akazvarwa muNeedham, Massachusetts, Arnold akapinda uye akatamba hockey yechikoro chepamusoro paNoble neGreenough Chikoro uye chirongwa cheBoston Junior Bruins asati ajoina USA Hockey National Team Development Chirongwa chemwaka wa2009-10. Pamutambo weU-17, Arnold aive kaputeni wechikwata chechikwata chakasarudzwa icho chakatora chikamu mumakwikwi mashanu emarudzi muSlovakia; akatumidzwa zita remutambi anokosha kwazvo mumutambo. Pa 2010 IIHF World U18 Championships, Arnold akarekodha mapoinzi matatu mumitambo mitanhatu seNational Team Development Program, inomiririra United States, yakahwina menduru yegoridhe. Pa
2010 National Hockey League (NHL) Entry Draft, Arnold akasarudzwa mumutambo wechina, 108th yose, neCalgary Flames.