Anatomy of running: CALF MUSCLES
Anatomy and Function
Running, whether it’s a marathon or a sprint, places significant demands on the posterior leg muscles. Two key players in the lower leg are the gastrocnemius and soleus muscles, commonly known as your "calf" muscles or triceps surae. Understanding their anatomy and function can help runners optimize their training and prevent injuries.
The gastrocnemius has two heads to the muscle, the larger and more visible of the two muscles forming the bulk of the calf. This muscle originates from the femur, crosses the posterior aspect of the knee joint and converges as the single achilles tendon. The medial head attaches at the medial condyle of the femur, while the lateral head attaches at the lateral condyle of the femur. The gastrocnemius is primarily responsible for plantarflexion of the foot (pointing the toes downward) and also assists in knee flexion.
The soleus is situated beneath the gastrocnemius, a flatter and deeper muscle originating from the proximal tibia and fibula. Like the gastrocnemius, the soleus inserts at the calcaneus via the achilles tendon. The soleus is involved in plantarflexion of the foot, particularly when the knee is in a flexed position.
Function in Running
During the gait cycle the gastroc-soleus complex concentrically produces a strong push-off at the terminal stance phase, propelling the runner forward. The distribution of load on these structures varies depending on terrain, biomechanics, and the speed of the runner.
Long, relatively slow efforts of moderate intensity require the endurance of the soleus muscle. The soleus is composed predominantly of type I "slow twitch" muscle fibers, and therefore is highly resistant to fatigue. Additionally the soleus helps maintain posture and stability of the lower leg over long durations of activity, ensuring efficient energy use and reducing risk of energy. While both muscles contribute to plantarflexion, the endurance capacity of the soleus ensures that runners can maintain an efficient stride for extended periods of time.
As speed increases from moderately-high effort tempo runs up to sprinting, the muscular power demands increase as well. The gastrocnemius muscle is critical in this context, as it contains a higher proportion of type II "fast twitch" muscle fibers which are capable of generating quick, forceful contractions. This allows for a more powerful stride, increased force through the ground at push-off to propel the runner further with each step. Additionally to its role in plantarflexion of the ankle, the gastrocnemius contributes to knee flexion which influences the characteristically high heel lift seen as running speeds increase.
Training the Gastroc-Soleus Complex
Strengthening and condition for the gastrocnemius may incorporate plyometric exercises like pogos, drop jumps from a box, and uphill sprints or sled push to enhance explosive power. Strengthening can be done with calf raises with a straight leg focus on gastrocnemius activation. Considering the increased type I fibers in the soleus, we may perform exercises like a forward lunge with heel raises, wall sit heel raises, seated calf raises and slow/heavy loading including heavy sled push, uphill walking to build strength and stamina in the soleus.
To improve flexibility in the gastrocnemius, we may target this muscle by stretching with a straight knee. Techniques like wall stretches, low load long duration heel hangs off a step, and downward dog yoga poses are effective. The soleus requires a bent-knee position to isolate its fibers. Modified wall stretches and front-foot elevated lunges driving the knees over the toes can help improve flexibility and ankle mobility.
Recovery and Injury Prevention
Most running-related injuries in this region of the body are a result of either training error or strength/mobility limitations relative to the demands placed upon the body. Training errors can be mitigated by finding the appropriate balance between rest and recovery, allowing adequate recovery time between intense training sessions to prevent overuse injuries such as achilles tendinopathy or muscle strains. Recovery may be enhanced with use of tools such as massage instruments or foam rollers to relieve tension and promote blood flow. Additionally we must not neglect holistic recovery modalities including sleep and stress-management.
The gastrocnemius and soleus muscles are indispensable for runners, each contributing uniquely to different types of running. By understanding their anatomy and function, and incorporating specific training and recovery strategies, runners can enhance performance and minimize the risk of injury. Whether you’re aiming for a marathon or a sprint, a well-conditioned gastroc-soleus complex is your ally on the road and the trails.
