'They're fast, but are they fair?' Amateur runners face Nike dilemma

Athletics - Dubai Marathon - Dubai, United Arab Emirates - January 24, 2020 General view of an athlete wearing the Nike Vaporfly shoes REUTERS/Christopher Pike

LONDON (Reuters) - British amateur runner and triathlete Holly Grundon was delighted to smash a long-held personal speed target - to finish a half marathon in less than 1 hour and 30 minutes.

But the 36-year-old's decision to switch to Nike's Vaporfly trainers before securing her new personal best (PB) time has her wondering whether she cheated herself, or dirtied a sport she's always loved for its purity.