Causes of Hip Flexor Pain in Triathletes + How to Fix It

Jun 08, 2023
hip flexor pain

Hip flexor pain in triathletes is a relatively common phenomenon because of the tremendous demand placed on them in each of the three triathlon disciplines. Swimming, cycling and running all stress this group of muscles repeatedly, both directly and indirectly. In this article we’ll explore the causes of this pain and how to fix tight hip flexors for triathletes at all levels.

What Are Hip Flexors?

When we use the term hip flexors it is in reference to a particular group of muscles whose primary function is to flex the hip. Hip flexion can be defined as movement of the thigh towards the front of the body. For example, raising your knee up towards your chest, or lying down and lifting your leg straight up towards the sky.

The two main hip flexor muscles are iliopsoas (composed of the iliacus and psoas major muscles) and rectus femoris (a quadriceps muscle). These muscles work together to contract and pull the thigh towards the abdomen, a function that occurs when you kick while swimming, on the upstroke while pedaling, and in the swing phase of your running gait.

With the above knowledge in mind, we can already start to form a preliminary understanding of why triathletes develop hip flexor pain. No matter which sport(s) you’re training on a particular day, or what distance of triathlon you’re competing in, you will throughout the process contract these muscles hundreds of thousands of times.

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Triathlete Hip Flexor Pain: Causes

To determine the cause of a triathlete’s hip flexor pain, it is best to look at each of the three sports individually. Let’s dive briefly into the unique factors that may be overloading or otherwise hindering the hip flexors of a triathlete while swimming, cycling, and/or running.


Swimming’s weightless environment in the water provides some unique challenges to the body. It can be harder to get different muscle groups working together, especially for beginners, because they now have a distorted feedback loop that they’re not accustomed to; i.e. moving against the resistance of water as opposed to gravity.

Having a strong, well-integrated core is extremely important for success while swimming. If you already have poor coordination and strength in your abdomen, it will be even harder to activate it properly while swimming. This can result in your legs working in isolation and trying to kick the rest of your body through the water, almost guaranteeing overload of the hip.

The hip flexors are vulnerable to overuse as a result of the above point and the excessive kicking motions of swimming. There is a fine balance between how much upper body one should use and how much lower body one should use to be most efficient in the water. The muscles in your legs are stronger, but using them too much can be extremely fatiguing.


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Bikes were made for humans, but humans were not made for bikes. The hip joint in particular is compromised while cycling largely because it never fully flexes or extends throughout the pedal stroke, and is exacerbated by the forward folded torso. This means the hip flexor muscles are always in a semi-shortened position, which can have detrimental long-term consequences.

Davis’s Law is a concept used in anatomy and physiology stating that soft tissue will model itself according to the stress imposed upon it. In the case of a chronically shortened muscle, it will eventually respond by dropping sarcomeres (the base units of muscle), resulting in a physically shorter muscle that cannot return to its normal length.

This cramped position is further aggravated by increased time spent sitting whilst doing other activities in modern life; office work, driving, watching TV, etc. Seated positions shorten our hip flexors, make them tight, and often contribute to ache, pain, and irritation in the front of the hip. Sitting also weakens the muscles on the other (back) side of the hip, namely your glutes.


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Running is certainly the highest impact of each of the three sports, and is also the only one where you are working against the full force of gravity (the bike supports much of your weight while cycling). Research shows that you can experience forces over 3x your bodyweight while running, suggesting that wear and tear might be more prevalent in certain bodily structures.

The two phases of gait are relevant here when talking about hip flexor pain. As a person finishes stance phase and transitions to swing, their leg is behind them and preparing to swing through to the front of their body in preparation for landing. The hip flexors help pull the leg through swing phase, and this is something that takes place thousands of times during a run.

Poor running form can place excessive strain on the hip flexor muscles, particularly if the athlete is pulling their leg too far forward out in front of them. This is often seen in people who heel strike as opposed to a mid-forefoot strike, and carries other problems in the forms of excessive braking and reduced shock absorption.

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Triathlete Hip Flexor Pain: Fixes

With all that background out of the way, we can now focus on treatment for hip flexor pain and solutions that broadly apply across each of the three disciplines. 

Form Coaching

Doing a one-on-one session with a professional coach in each sport (not a triathlete, but someone who is a dedicated swimmer, cyclist, and runner) is one of the most worthwhile investments a person can make. These people will have an eye for identifying inefficiencies and make sure you aren’t overusing the hips as a result of weakness, positioning, or just faulty movement patterns.

Bike Fitting

For cycling, if your bike is not fitted to you properly, you can overload the hip flexors in a number of ways. For example, if the handlebars are too low, you will lean too far forward, cramping the hip joint. If the saddle is too low, you will have excessive hip flexion and over-facilitation of the hip flexors. So on and so forth.

Lower Abdominal Training

Training the lower abdominals teaches you to stabilize your pelvis (by rotating it backwards) and lower back against the pull of your hip flexors (your psoas attaches to your low back). This is achieved by doing exercises like a single leg raise (below) where you focus on keeping your lower back flat on the ground as you lift each leg up and down.

Before lifting your leg, rotate your pelvis back so there is no space between your lower back and the ground. Maintain this position throughout. This forces the core muscles to resist the pull of the hip flexors, and teaches them to work together during hip flexion. Try a set of 5-10 on each side to start.

Strengthen the Hip & Leg

By participating in a comprehensive strength training program designed for triathletes, you will develop all the muscles around the hip joint and give it the balance it needs to thrive while swimming, cycling, and running. Exercises like squats, lunges, deadlifts, hip thrusts, calf raises, and hamstring curls are all great movements that you should be doing regularly.

Hip Flexor Stretches & Mobility

Finally, you can provide some relief to overworked, tired hip flexors by gently stretching and mobilizing them. If you are currently experiencing hip flexor pain and are still trying to train, you can try stretching them prior to your swim, bike, or run. This offers a temporary dampening effect that relaxes over-facilitated hip flexors, allowing other muscles to work instead.

Low Lunge Stretch: Focus on keeping the butt squeezed and the pelvis rotated back to support the lower back and emphasize stretching the hip flexor muscles themselves. Perform for 30-60 seconds on each side.

 Hip Rehab for Triathletes

Looking for a program that will help you address the muscle imbalance that is likely causing your hip pain? Dynamic Triathlete is an online training platform designed to help triathletes become stronger and faster while training pain free for years to come. Complete your regimen with an all-inclusive program that addresses mobility, flexibility, strength and injury prevention, all for a fraction of the cost of one physiotherapy appointment. Try out our 6 Week Hip Function & Rehab Program and experience the results for yourself. Click here to try 7 days free!

 Written by Eric Lister – Certified Personal Trainer & Corrective Exercise Specialist

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