For each exercise, gradually increase the number of repetitions until you reach the top of the suggested rep range, then increase the number of sets.
The first exercise, and also the most challenging, is the chin-up, which works your upper back, rear shoulders and biceps.
It’s best to perform chin-ups using an “underhand” grip, with your palms facing toward you on the bar. Use a door frame or tree branch if you need help locating a bar.
Do one to three sets of 5 to 10 repetitions every other day.
Next up is the push-up, which targets your chest, front shoulders and triceps.
Do one to three sets of 15 to 30 reps every other day. Just be sensitive to signs of lower-back discomfort, as push-ups place stress on your lumbar spine.
The third exercise is the twisting trunk curl, which works the abdominal and oblique muscles of your midsection.
Lying on your back with your knees bent and feet flat on the floor, lift your head and shoulders off the ground just like a regular abdominal crunch, but twist your body to the side – alternating left and right – on the way up.
Do one to three sets of 15 to 30 slow and controlled reps every other day.
The final exercise is the trunk extension for the lower back muscles, a particularly vulnerable area for runners.
Lying face down with your elbows out and hands under your chin, lift your chest a few inches off the floor, then lower it. Do one to three sets of 5 to 15 reps, slow and controlled, on the same days as the twisting trunk curls.