Crutches are a common mobility aid used temporarily to help a person move while recovering from a lower extremity injury or surgery. Their primary function is to offload weight from the injured leg, knee, or ankle, allowing for non-weight-bearing, partial weight-bearing, or toe-touch-only ambulation. Using crutches requires significant physical exertion, engaging a complex network of muscles throughout the upper body and torso. This method of locomotion demands strength and coordination to maintain balance and achieve forward momentum.
The Core Movers: Muscles in the Upper Body
The process of moving forward with crutches, often called a swing-through or three-point gait, depends heavily on the muscles of the arms and shoulders for propulsion and support. The Triceps Brachii, the large muscle on the back of the upper arm, acts as the primary extension muscle. It generates the powerful push-off force needed to lift the body off the ground, repeatedly contracting with each step as the elbow straightens to bear the user’s weight through the handgrips.
The Deltoids, which cap the shoulder, are continuously engaged to stabilize the shoulder joint and position the crutches during the swing phase. The anterior part of the deltoid muscle helps lift and control the shoulder as the crutches are moved forward. The Pectoralis Major, the large chest muscle, assists the triceps in pressing down on the handgrips, providing additional power and stability for the downward push.
Forearm and hand muscles are also constantly at work, focusing on grip strength to maintain a secure hold on the crutch handles. Without a firm grip, the body’s weight cannot be effectively transferred through the crutches to the ground.
Stabilization and Balance: Muscles in the Torso and Hips
While the arms provide the power, the torso and hip muscles are responsible for maintaining an upright posture and preventing the body from swaying laterally. The Latissimus Dorsi, the broad muscles of the middle and lower back, play a role in pulling the shoulders down and back. This helps stabilize the shoulder blades and trunk against the downward force of the crutches, creating a stable base for the arms to push off from.
The Abdominal muscles, collectively known as the core, are continuously activated to prevent excessive torso rotation and maintain the body’s center of gravity. This constant contraction is necessary to achieve smoother movement and prevent loss of balance during weight transfer. Prolonged crutch use often results in improved core strength.
The Gluteal Muscles and Hip Flexors of the healthy, weight-bearing leg are also heavily recruited to stabilize the pelvis and control the movement of the healthy leg. With each step, the healthy leg must bear the full body weight plus the force generated by the crutches, demanding increased strength and endurance from the gluteus medius to prevent the pelvis from dropping on the injured side. This increased demand on the hip stabilizers often explains why a person may feel soreness in the non-injured side’s hip after extended crutch use.
Technique Matters: Maximizing Efficiency and Safety
Using crutches effectively requires proper technique, which directly influences muscle engagement and movement efficiency. The most important technique is to shift body weight through the hands and arms, not by resting on the axillary pads beneath the armpits. Resting on the pads can compress nerves and blood vessels, leading to a condition known as crutch palsy.
Proper adjustment of the crutch height is necessary to ensure the primary force is generated by arm and shoulder power. The handgrips should be positioned so the elbows are slightly bent (15 to 30 degrees), allowing the triceps to fully extend and provide the strongest push. Correct posture, involving keeping the crutches close to the body and looking forward, facilitates proper engagement of the core and back muscles for better balance.
Relying on the powerful downward extension of the arms and the stabilizing force of the torso maximizes movement efficiency. This focus on correct muscle action prevents unnecessary strain and fatigue, making ambulating on crutches safer and less taxing.