Chet Fortune works out using an altitude training mask at to increase his lung capacity. Fortune is a co-owner of Warrior Fitness Center in La Vista. Video: Weird mask, great workout In April, a few ...

All products featured here are independently selected by our editors and writers. If you buy something through links on our site, Mashable may earn an affiliate commission. Wearing a mask — like this ...

The performance-enhancing altitude mask that Olympic hopeful Sivert Guttorm Bakken was wearing when he was found dead this week “is not part of the Norwegian Biathlon Association’s organized training ...

The performance-enhancing altitude mask that Olympic hopeful Sivert Guttorm Bakken was wearing when he was found dead this week “is not part of the Norwegian Biathlon Association’s organized training ...

The performance-enhancing altitude mask that Olympic hopeful Sivert Guttorm Bakken was wearing when he was found dead this week “is not part of the Norwegian Biathlon Association’s organized training ...