Strong hip flexors drive your knee forward with each stride, help you maintain a longer step length, and keep your pelvis stable throughout a run. Most runners neglect these muscles because running itself feels like it should be enough, but the repetitive motion of distance running actually creates an imbalance that leaves hip flexors both tight and weak. Targeted strengthening, done at least twice a week, corrects that imbalance and can measurably improve your running economy.
What Your Hip Flexors Actually Do While Running
Your hip flexors are a group of muscles deep in your front hip, with the iliopsoas (a combination of two muscles running from your lower spine through your pelvis to your thighbone) doing the heaviest lifting. The rectus femoris, which is part of your quadriceps, and the sartorius, which angles across your thigh, also contribute.
During each stride, these muscles work in a coordinated sequence. As your foot leaves the ground, the rectus femoris and sartorius fire first to accelerate your leg forward in the early swing phase. Then the iliopsoas takes over during late swing, when your hip reaches peak flexion angle and your leg extends to its full stride length. This late-swing activation is what allows you to take longer steps without overstriding. The iliopsoas also contributes to lumbar and pelvic stability, helping maintain your trunk posture so energy goes into forward motion rather than compensating for a wobbly core.
When you increase your cadence (taking faster steps), the rectus femoris and sartorius work harder to rapidly flex the hip and accelerate the limb. When you increase step length, the iliopsoas ramps up significantly. This means both speed work and long runs place high demands on different hip flexor muscles, and weakness in any part of the group limits your performance.
Why Runners Are Both Tight and Weak
Here’s the counterintuitive part: your hip flexors can feel extremely tight while simultaneously being weak. Runners often assume tightness means the muscles are overworked and strong, so they stretch aggressively. But the tightness is frequently a protective response to weakness and overuse without adequate strengthening.
The underlying problem starts with muscle imbalances. During running, your calves, hamstrings, and quadriceps do enormous work and grow progressively stronger. Your glutes, which should be powerful hip extensors, often remain underactive compared to these other groups. When the glutes don’t pull their weight, the hip flexors compensate by staying in a shortened, “guarded” position. This creates an exaggerated forward pelvic tilt where your lower back arches and your butt sticks out. The tight hip flexors then make it harder to engage your abs effectively, compounding the instability.
Static stretching alone can’t fix this. A few seconds of stretching doesn’t undo the hours of repetitive shortening that running causes. Contracting and strengthening the muscles that are chronically lengthened and weak produces a far greater effect than passively stretching the ones that feel tight. For most runners, this means actively strengthening the hip flexors and glutes together rather than just stretching and foam rolling.
How Stronger Hip Flexors Improve Running Economy
Running economy is essentially how much energy you burn at a given pace. The less energy you waste, the easier a pace feels and the longer you can sustain it. Research on recreational runners found that the ratio of hip flexor strength to hip extensor strength was strongly correlated with running economy, particularly at moderate speeds and on inclines. Runners with relatively stronger hip flexors compared to their extensors used less energy at the same pace.
The key word is “relative.” Absolute hip flexor strength on its own didn’t predict running economy. What mattered was the balance between the front and back of the hip. This makes physiological sense: if your extensors (glutes and hamstrings) overpower your flexors, the flexors can’t efficiently recover the leg during swing phase, and you waste energy with each stride. Strengthening your hip flexors to match your already-strong extensors closes that gap.
How to Test Your Hip Flexor Strength
A simple self-check: stand on one leg and drive the opposite knee up to waist height. Hold it there for 10 to 15 seconds without leaning your trunk backward or letting the knee drop. If you can’t hold the position, or if you feel the effort mostly in your lower back rather than the front of your hip, your hip flexors are likely weak relative to your body weight and running demands.
For a more specific assessment, the Thomas Test distinguishes between tightness and weakness. Lie on your back at the edge of a table or high bed, pull one knee to your chest, and let the other leg hang freely off the edge. If the hanging thigh rises above horizontal, you have tightness in the one-joint hip flexors (iliopsoas). If the knee straightens out instead of staying bent at roughly 90 degrees, the two-joint muscles (rectus femoris) are tight. But tightness and weakness coexist in runners, so even if the test shows shortness, you still benefit from strengthening rather than just stretching.
Five Exercises That Build Hip Flexor Strength
Aim for 2 to 3 sets of 10 to 12 reps per exercise, at least twice a week. Space your sessions at least 48 hours apart, and avoid doing heavy hip flexor work the day before a hard running workout.
Standing Marches With Resistance Band
Loop a resistance band around both feet. Stand tall and drive one knee up toward your chest against the band’s tension, keeping your standing leg locked and your torso upright. Lower slowly. This directly mimics the swing-phase motion of running while loading the iliopsoas through its full range. Focus on pulling the knee high rather than leaning back to cheat the movement.
Hanging Knee Raises
Hang from a pull-up bar with arms straight. Raise both knees toward your chest without swinging, then lower under control. If a pull-up bar isn’t available, do these lying flat on your back (reverse crunches), pressing your lower back into the floor as you bring your knees up. This exercise strengthens the hip flexors and lower abdominals together, addressing the core-stability component that tight hip flexors often compromise.
Psoas March (Seated)
Sit on the edge of a chair or bench with your feet flat on the floor. Place your hands on top of one thigh and press down while simultaneously driving that knee upward against your hands. Hold the contraction for 3 to 5 seconds, then switch sides. This isometric hold isolates the iliopsoas without involving momentum, building strength at the exact joint angle where many runners are weakest.
Single-Leg Lowering
Lie on your back with both legs straight up toward the ceiling. Keeping your lower back pressed into the floor, slowly lower one leg until it hovers a few inches above the ground, then bring it back up. The working hip flexor on the lowering side controls the descent eccentrically, which builds the kind of deceleration strength needed during late swing phase when your leg extends before foot strike.
Banded Hip Flexion in Split Stance
Anchor a resistance band behind you at ankle height. Step into the band with one foot and stand in a staggered stance. Drive the banded knee forward and up, holding briefly at the top. This replicates the propulsive demand of running against resistance, training the hip flexors to generate force while the opposite leg stabilizes your pelvis, just as it does mid-stride.
How to Fit This Into Your Running Schedule
The twice-a-week minimum is non-negotiable for building strength rather than just maintaining it. Most runners find it easiest to pair hip flexor work with their regular strength sessions on easy run days or rest days. If you’re currently doing no strength training at all, start with just 2 sets of each exercise and build to 3 over two to three weeks.
Progression matters more than adding exercises. Once 12 reps feel comfortable, increase the band resistance, add a light ankle weight, or slow down the eccentric (lowering) phase to 4 seconds. The hip flexors respond to progressive overload just like any other muscle group, and runners who plateau often do so because they’ve been doing the same bodyweight routine for months without increasing the challenge.
You can also integrate activation drills before runs. A single set of 8 to 10 standing marches per side, done at moderate effort without a band, primes the hip flexors and reminds your nervous system to recruit them during your stride. This is especially useful before speed sessions or hill workouts, where hip flexor demand is highest.
Injury Risks From Neglecting Hip Flexor Strength
The most direct risk is a hip flexor strain, which causes sharp pain at the front of the hip and can sideline you for weeks. But the downstream effects of weakness are often more insidious. When hip flexors can’t adequately control pelvic position, your lower back compensates, leading to lumbar pain that many runners mistakenly attribute to core weakness alone. The altered mechanics can also contribute to hip impingement, where the thighbone and pelvis compress soft tissue during deep flexion.
Weak hip flexors also change how forces distribute through your legs. If you can’t drive your knee forward efficiently, your hamstrings and calves absorb more impact and do more work than they’re designed for at those angles. Over a training cycle, this redistribution of load increases the risk of strains in those overworked muscles. Strengthening the hip flexors doesn’t just make them more resilient to strain. It protects the entire kinetic chain by keeping each muscle group working in its intended role.