The Big Book of Endurance Training and Racing storage Engineered for the perfect fit

Engineered for the perfect fit

Ultralight fill

The soft and secure bite valve delivers a steady flow with a simple flip

Round neckline and printed with the Fjällräven logo on the front

stretchable Women's Etip™ Recycled Glove is a runner’s favorite

The Big Book of Endurance Training and Racing storage Engineered for the perfect fitAre you a triathlete, runner, cyclist, swimmer, cross country skier, or other athlete seeking greater endurance? The Big Book of Endurance Training and Racing teaches athletes how to stay healthy, achieve optimal athletic potential, and be injury free for many productive years. Dr. Philip Maffetones approach to endurance offers a truly individualized outlook and unique system that emphasizes building a strong aerobic base for increased fat burning,