A large number of muscle groups are active to varying degrees in the freestyle stroke primarily used by triathletes and long distance swimmers. It’s useful therefore to have an understanding of these muscles when identifying any potential shortfall in your stroke.
The Upper Body: The Stroke
Active during the initial phase of the pull stabilising the forearm for a strong pull and later active during the recovery phase of the stroke. Strengthening the Bicep can therefore be beneficial in providing more propulsive force.
Example Exercise: Bicep Curl
Key in the extension of the arm during the mid and late pull phases of the freestyle stroke. Developing strong triceps is therefore beneficial in developing more propulsive force.
Example Exercise: Tricep Extension
The deltoids are responsible for the rotation of the shoulder joint. They therefore see a large amount of use throughout all phases of the stroke but primarily in the recovery phase returning the hand to the overhead position. The deltoid is also key in stabilising the shoulder joint during the pull phase of the stroke along with those muscles composing the rotator cuff.
Example Exercise: Arnold Press
Pectorals & Latissimus Dorsi
Combined these two muscles provide the majority of power throughout the pull phase of the freestyle swimming stroke. The pectorals major handles the initial part of the pull through whereas in the late phase of the stroke the Latissimus Dorsi takes over.
Example Exercise: Chest Pullover
The serrated anterior is active throughout the entire duration of the swim stroke and us essential to maintaining stability within the shoulder joint and scapular. Specific strengthening exercises for the serrated anterior are therefore beneficial in promoting optimum performance.
Example Exercise: Scapular Push Up
Often observed as being well developed in competitive swimmers the trapezius is primarily involved in the stabilisation of the shoulder blade and is mainly active during the recovery phase of the stroke.
Example Exercise: Shrugs
Works as synergistic to the Latissimus Dorsi during the mid to late pull phase of the swimmers stroke. Provides additional power as well as helping to stabilise the shoulder.
Example Exercise: Medial Rotation of the Shoulder
Works as an antagonist muscle to the pectorals during the internal rotation of the shoulder in the mid phase of the pull through the water.
Example Exercise: Lateral Rotation of the Shoulder
Active while in the high elbow position during the initial phase of the pull as well as the recovery phase of the stroke. Responsible for stabilising the shoulder and provides some power in the initial pull.
Example Exercise: Bent Over Row
Subscapularis, Supraspinatus & Infraspinatus
Both Active throughout the recovery phase of the stroke but primary function is to act as a stabiliser for the shoulder.
Example Exercise: YTWL
The Lower Body: The Kick
Rectus Femoris is key in the initial phase of the kick and provides a more powerful kick generating extension at the knee and increasing propulsive force.
Example Exercise: Barbell Squat
Main hip extensor responsible for the recovery or upbeat phase of the swimmers kick.
Example Exercise: Hamstring Curl
Gluteal muscles (Maximus & Minimus)
Key hip flexor contracting during the initial recovery phase of the kick prior to the activation of the hamstring
Example Exercise: Glute Bridge
Key in the initial phase of the downbeat or propulsive phase of the swimmers kick initiating movement at the hip and knee.
Example Exercise: Double Leg Raise
Additional Hip Flexors
A number of additional muscles are active in controlling and stabilising the internal and external rotation of the hip during the swimmers kick including the adductors, Sartorius and a number of other small muscles.
Example Exercise: Knee Raise
Controlling the foot
Gastrocnemius, Soleus & Tibialis Anterior all function to maintain the plantar flexed position of the foot against the pressure of water during the propulsive phase of the kick.
Example Exercise: Calf Raise
The Core: Body Roll and Position
The main muscles of the core include those located in the lower back (Erector Spinae) and the abdominals (Transverse & Rectus Abdominus) are active near constantly providing a stabilising force for the body.
Example Exercise: Plank Hold
The Internal & External Obliques are responsible for the rotation of the trunk and provide a strong body rotation in the water.
Example Exercise: Trunk Rotation