Interval training. Just the words alone can make us shudder. They aren’t your nice, steady state, zone 2 run. No. Instead, they’re sprints, shuttle runs, tempo efforts, hill climbs. None of it is nice. All of it will test your lungs and legs.  But if you can learn to find beauty in the suffering, there are tremendous benefits to incorporating interval sessions once a week. They’ll help your marathon endurance training , build strength throughout your body, supercharge your mental resilience, and, crucially, shave precious minutes off your PB. Here’s everything you need to know. Want the latest fitness advice and workouts to tackle any adventure? Sign up for our Blueprint newsletter . The Benefits of Interval Training for Endurance Athletes ‘Need’ is a strong word, but intervals are pretty great for you.…