Blog 2: Everything Triathlon
Part 2: The Most Common Triathlon Injuries — And the Real Reasons They Happen
Welcome back to Everything Triathlon. In Part 1 Dr. Keirstyn covered why training across three disciplines creates a unique injury environment and why the run leg is where most problems express themselves even when the cause is upstream. Now we get specific with the injuries I see most consistently in triathletes and exactly what's driving them.
1. Running Overuse Injuries — The Most Common Category
Because the run is performed in a fatigued state after the swim and bike, running injuries dominate the triathlon injury landscape. The most frequent:
IT Band Syndrome:
Lateral knee pain that appears at a consistent distance into the run and forces you to stop. In triathletes, glute fatigue from the bike is a major driver. When the glutes are no longer effectively stabilizing the hip after two hours of cycling, the IT band compensates. The run is where it fails.
Patellofemoral Pain (runner's knee):
Pain around the kneecap, especially on descents or after long brick sessions. The quad dominance that develops on the bike loads the patella, and running with already-fatigued quads amplifies it.
Stress Reactions and Stress Fractures:
More common in higher volume training blocks and in athletes who increase run mileage too aggressively relative to their bone density and nutrition status. The tibia and metatarsals are the most common sites in triathletes.
Plantar Fasciitis and Achilles Tendinopathy:
Both are load-dependent overuse injuries that develop when run volume increases faster than the tissue can adapt. The transition from bike to run in training is a particular trigger. The calf and Achilles are working in a shortened position on the bike and then asked to load eccentrically immediately in the run.
2. Swimmer's Shoulder
The shoulder is the primary engine of the swim and takes on significant repetitive loading across a triathlon training season. Swimmer's shoulder is an umbrella term covering several presentations:
Rotator Cuff Impingement:
The most common, driven by repetitive overhead motion with poor mechanics. In triathletes who swim less frequently than pure swimmers, technique tends to be less refined and compensation patterns more pronounced.
Rotator Cuff Tendinopathy:
Develops when shoulder volume increases too quickly or when stroke mechanics break down under fatigue. Entry-hand crossover, dropped elbow at catch, and inadequate rotation are the mechanical culprits I see most.
Biceps Tendinopathy:
Pain at the front of the shoulder, often worse with the catch phase. Frequently accompanies rotator cuff issues as a secondary structure under excess load.
For sprint and Olympic distance triathletes, the swim is shorter but often is swam at a higher relative intensity —> which means mechanics break down faster and the shoulder is loaded at a greater rate for the distance.
3. Cycling-Related Issues
The bike leg creates a specific set of problems that often don't announce themselves until the run:
Lower Back Pain:
Sustained hip flexion posture on the bike compresses the lumbar discs and tightens the hip flexors. Athletes with poor thoracic mobility compensate by rounding the lower back. After two to four hours in this position, the lumbar spine is in no condition to absorb run impact.
Knee Pain from Bike Fit:
Saddle height is the most common culprit. Too low and the knee is loaded at a compression-dominant angle all ride. Too high and the hip rocks with every pedal stroke, loading the IT band and lateral structures. A proper bike fit is one of the single highest-return investments a triathlete can make.
Hip Flexor Tendinopathy:
The psoas and rectus femoris work continuously throughout the pedal stroke. High volume cycling without adequate hip flexor loading capacity leads to tendinopathy at the hip or anterior thigh, often perceived as a groin or deep hip ache.
4. Overtraining: The Triathlon-Specific Injury Risk
Triathlon carries a unique overtraining risk because three disciplines each feel individually manageable. An athlete who swims four times, bikes four times, and runs four times per week might feel like each individual session is fine — but the cumulative load is equivalent to what many professional athletes carry. The body doesn't distinguish between sports when it's tallying recovery demand. In the next blog we are going to dive deep into what I have come to believe is the most important area to train as a triathlete —> STRENGTH. Stay tuned!
Overtraining syndrome in triathletes presents as: persistent fatigue that doesn't resolve with a rest day, declining performance despite consistent training, elevated resting heart rate, frequent illness, mood changes, and motivation loss. These are not signs of weakness, they're signs the load has exceeded the body's adaptive capacity.
Up Next — Building Your Triathlon Body
You know what breaks down and why. Part 3 of Everything Triathlon covers the strength, mobility, and preparation work that keeps you healthy through your build and across all three disciplines. See you there.
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Recognize any of these injury patterns in your own training? Don't wait for a DNF to do something about it. I work with triathletes to find the actual driver of their injury — not just treat the symptom. Book an assessment at Endurance Therapeutics with Dr. Keirstyn today and let's sort it out!
📍 Endurance Therapeutics | Oakville, Ontario
📞 905-288-7161