Breaststroker’s knee is an overuse injury commonly seen in swimmers, particularly those who specialise in breaststroke. The breaststroke kick, also known as the whip kick, places repetitive stress on the medial (inner) structures of the knee due to its unique biomechanical demands. Unlike other strokes, breaststroke involves a wide, circular motion of the legs that combines external rotation, abduction and forceful extension. Over time, this can irritate or damage the soft tissues in and around the knee joint.
While it most often affects competitive swimmers, breaststroker’s knee can also develop in recreational swimmers or those training intensively. Understanding this condition is key to managing symptoms and preventing long-term knee issues. It is said that the two structures most commonly affected by this condition are the medial collateral ligament (MCL) and the pes anserinus due to the location of these structures and the mechanical demands placed on them with this swim style.
Signs and Symptoms
Breaststroker’s knee typically presents with symptoms on the inner side of the knee and may range in severity depending on the swimmer’s load, technique, and individual biomechanics. Common symptoms can include:
- Pain on the medial (inner) side of the knee, especially during or after swimming
- Discomfort during the breaststroke kick, particularly at the whip phase (when the legs snap together)
- Swelling or tenderness around the medial collateral ligament (MCL) or medial joint line of the knee
- Sensation of clicking or catching in the knee with movement
- Decreased kicking power or avoidance of breaststroke due to pain
- Tightness in surrounding muscles, especially the adductors, quadriceps, and hamstrings
In chronic cases, athletes may report symptoms even during walking, squatting, or prolonged sitting.
Differential Diagnosis
Breaststrokers knee can mimic symptoms of other common conditions such as patellofemoral pain syndrome, MCL sprain or medial meniscus irritation. Hence, it is important to liaise with your physiotherapist to ensure you are maximising your treatment outcomes. Diagnosis is a process of clinical reasoning based on the mechanism of injury, location and quality of pain and other relevant history.
Causes and Contributing Factors
Breaststroker’s knee results primarily from repetitive stress and biomechanical overload. The whip kick causes the lower leg to rotate outward (external tibial rotation) and open sideways (abduction), which can strain the MCL and other structures on the inner side of the knee. Studies have revealed that there is a correlation between factors such as age, years of competitive swimming and training volume, and the likelihood of experiencing medial knee pain.
Common contributing factors include:
- Poor Technique: Excessive external rotation or knee valgus during the kick phase.
- Muscle imbalances and poor patella tracking.
- High Training Volume: Repetitive loads without adequate recovery.
- Anatomical Variations: Hypermobile joints or naturally wide hip angles (increased Q angle).
- Fatigue: As fatigue sets in, form deteriorates, increasing the likelihood of stress on the knee
Relevant Anatomy
The pes anserinus is a term used to describe the combined tendons of three muscles that attach along the inner side of the upper shin bone (proximal medial tibia). These muscles are:
- Sartorius: Runs down the front of the thigh and assists in hip flexion and knee flexion.
- Gracilis: A muscle of the inner thigh that helps adduct the hip (bring the leg inward).
- Semitendinosus: One of the hamstrings, which helps bend the knee and extend the hip.
These three tendons fan out like a goose’s foot (hence the Latin term pes anserinus) and insert on the tibia just below the knee joint. Beneath the tendons lies a small fluid-filled sac (bursa) that reduces friction. The pes anserinus provides dynamic stability to the inner knee during movement.
The MCL is a broad, flat ligament that runs along the inside of the knee joint. Its main job is to stop the knee from collapsing inward (valgus stress).
The combination of valgus stress and repeated knee flexion/rotation places tension on both the MCL and the pes anserinus tendons due to the location and actions of both structures. Over time, this can lead to irritation and inflammation.
Prognosis
Most swimmers with breaststroker’s knee recover fully with appropriate management. Early identification and a tailored rehabilitation plan are key. Recovery can take a few weeks for mild cases, while chronic or severe presentations may take several months, especially if technical changes are needed.
Adherence to physiotherapy, modifying swimming routines, and gradual return to full training typically lead to good outcomes. Rarely, if the problem persists or other injuries develop, medical imaging or further intervention may be necessary.
Treatment
Physiotherapy and Rehabilitation
Rehabilitation focuses on reducing inflammation, correcting biomechanical contributors, and improving the strength and flexibility of key muscle groups.
1. Load Management
- Temporary reduction or cessation of breaststroke training
- Modify training to focus on other strokes (e.g., freestyle, backstroke)
- Ice therapy may have anacedotal evidence following training sessions
2. Manual Therapy
- Soft tissue release for tight adductors, hamstrings, or hip flexors
- Joint mobilisation of the hip or knee if restrictions are present
3. Stretching
- Adductors, quadriceps, hamstrings, and calf muscles
- Hip flexor stretches to reduce anterior pelvic tilt
4. Strengthening
- Gluteus medius and maximus for pelvic stability
- Core strengthening to support overall lower limb control
- Quadriceps and hamstring co-contraction for balanced knee support
5. Neuromuscular Control
- Single-leg balance and control exercises
- Proprioceptive drills on unstable surfaces
- Functional exercises simulating swimming positions
6. Technique Retraining
- Video analysis of the swimmer’s kick
- Adjusting to a narrower, more controlled kick may reduce knee strain
- Coaches and physiotherapists can work together to guide technique correction
Other Management Strategies
Taping or Bracing
- Medial knee taping may offload stress during rehab
- Braces are rarely required unless instability is present
Medication
- Anti-inflammatories (e.g., ibuprofen) may be used short-term under medical advice
Cross-training
- Land based exercises, such as cycling or water running, to maintain fitness while offloading the knee in the pool
Return to Swimming
Return should be gradual, starting with strokes that don’t irritate the knee (e.g., freestyle), and progressing to short breaststroke sets. Swimmers are encouraged to:
- Avoid kick sets early in rehab
- Focus on upper body training (e.g., pull buoy work)
- Monitor for recurrence of pain and adapt training loads accordingly