If you reside in the US I would strongly suggest to go after one of the well known certifications offered by organizations like NSCA, ACE, ACSM, NASM. Online certifications won’t do you much for your time and money spent. You need a certification that provides continuing education and not a weekend warrior mentality. For sports conditioning you can refer to NSCA (www.nsca.com) for more information. Also if you want to get some experience and mentoring in triathlon training you can contact USA Triathlon organization (www.usatriathlon.org) for more information as well. I hope this helps. Good luck.