There’s a crew I once ran with on Mondays who after finishing the run would as a group do 8 Minute Abs, eight different 1-minute floor exercises for core strength. There was no formal structure to what exercises the crew did, other than they always finished with a 60 second plank.
Strength training after easier runs is typically a good idea, a low key, short opportunity to engage the core muscles a little bit after a low key run.
Most top training programs ask you incorporate a modicum of strength training in whatever form. Hal Higdon’s intermediate plans ask for you to do a bit of strength work after easier early-week runs. Brad Hudson and others swear by hill sprints as a low-impact way to strength train your lower body running muscles. The Hanson Marathon Method has you do some faster-than-marathon tempo runs as a sort of “strength” workout.
Your legs and hips aren’t the only muscles important to healthy, quality running form. Your upper body requires engaged core muscles to maintain a solid alignment that supports and augments, rather than inhibits, your running efficiency.
Many people as they tire begin to fall back into bad posture, though many run with bad posture whether or not they’re tired. Bad posture pulls the core and hips in one direction and gives your glutes/flexors more work to do on top of continuing to take steps with a(n often) tired lower body.
There’s all sorts of resources on effective posture but I’ll hit the basics:
When standing, a healthy aligned torso is upright and relaxed yet strong atop the hips, not pulling or leaning hard in any direction. The head and neck don’t necessarily have to be straight atop the shoulders, but shouldn’t droop forward. The shoulders should be strong and relaxed, not hunched.
When running, there may be a slight lean forward of the upper body, like how a Segway is prompted to move when you ride it. But the head, neck and torso otherwise remain strong and aligned atop your hips as you run. Nothing should hunch forward.
I don’t mean to turn this into a posture post. I only point this out to highlight the importance of core strength in your running development. Without a strong core, most of the keys to posture I described will be difficult if not impossible for someone lacking any of the above to develop and maintain. You can’t force good posture that sticks. There must be strength behind better habit formation.
Some core training is certainly valuable for improving not just your running, but your overall posture and alignment, a key component to effective running. It obviously won’t guarantee improvement, but it can certainly help.
However, like any training, it’s important not to overdo core training. This is a key reason top training plans don’t ask you to strength train in any way more than twice a week.
Imagine an example of a guy who tries to train for a marathon, while still lifting weights six times a week. Unless he’s taking performance enhancing drugs and eating 4000+ calories a week, he’s probably going to break down, burn out, get injured, drop dead… take your pick of any of the above. Even if his powerlifting doesn’t involve his running muscles and his running never involves his swole upper body… it’s asking too much of his organs, hormones, nutrition and recovery to effectively rebuild and maintain ALL of that.
To a lesser extent, consider that if you’re not already planking hard every single day or hitting Orange Theory or the Pilates studio all week long… your core has a limited capacity for strenuous exercise. Your body has a limited capacity for facilitating the rebuild and recovery from moderate to hard exercise, and you’re already taxing it with regular running. The capacity to handle additional core training and the effective recovery and growth from all of the above has limits.
So yes, do some core training once or twice a week. But the more running volume you ask of yourself, the less cross training you should ask of yourself.
8 Minute Abs isn’t too much. A quick blast of core work after a shorter run is honestly a great idea.
But a full, challenging strength workout on top of a distance run might be. It’s like how asking you to do difficult reps after a long run might be too much.
What your effective middle ground is depends on a lot and is your call. I encourage you to take it easy and add strength training gradually in small bite-sized increments. And definitely cut back on strength training during more difficult training periods such as peak mileage weeks or race weeks.
Remember that your top goal is to be in your best running shape. Make sure your core training sets you up for success, rather than hindering it.