Muscular Strategy Shifts in Sprint Training: Implications for Training Cues and Exercises
Discover how understanding the shift in muscular strategies can transform your sprint training
Effective sprint training requires an in-depth understanding of the physiological demands sprinters face as they accelerate and maintain high speeds. This post summarises a 2012 study highlighting the muscular strategy shifts that occur as sprinters increase their running speed. This article explores the findings of their study, discusses the key muscular adaptations, and provides practical implications for track coaches.
Key Finding 1: The Shift at 7 m/s
The study revealed that as athletes increase their speed, they shift from relying on the ankle plantarflexors (soleus and gastrocnemius) to the hip muscles for achieving further acceleration. This change occurs around the 7 m/s mark, which is particularly relevant for sprinters who race at speeds consistently above this threshold.
Below 7 m/s: The Role of Stride Length
At lower speeds, up to around 7 m/s, increasing stride length is the primary mechanism for improving running velocity. The soleus and gastrocnemius play a significant role in generating vertical ground reaction forces that propel the body upwards and forwards. This action enhances the time the sprinter spends in the air, contributing to a longer stride.Above 7 m/s: The Shift to Stride Frequency
As speed increases, ground contact time decreases, limiting the effectiveness of the ankle plantarflexors. The force-velocity relationship of muscles means that at higher velocities, the ability of the soleus and gastrocnemius to generate force diminishes. Beyond 7 m/s, the focus shifts to increasing stride frequency, which is achieved through faster leg swing facilitated by the hip muscles—specifically the iliopsoas, gluteus maximus, and hamstrings.These muscles accelerate the legs during the swing phase, increasing stride rate and contributing to the sprinter’s maximum velocity.
Sprinters require powerful accelerations, but maintain speeds above 7 m/s for most of the race, so training must prioritise hip muscle strength and the ability to rapidly accelerate the legs during the swing phase. Key exercises should target the hip flexors, glutes, and hamstrings to maximise stride frequency and maintain efficient leg turnover.
Training Recommendations
Early Acceleration Phase (Below 7 m/s):
Strengthen the Ankle Plantarflexors: Use heavy resistance exercises like calf raises to develop the force-generating capacity of the soleus and gastrocnemius.
Plyometrics: Incorporate exercises that enhance the explosive power of the ankle plantarflexors, such as depth jumps and bounding.
Maximum Speed Phase (Above 7 m/s):
Strengthen the Hip Flexors: Prioritise exercises that develop the iliopsoas, gluteus maximus, and hamstrings to enhance rapid leg swing.
Resisted Leg Swings: Use resistance bands or light weights to overload the hip muscles during the swing phase. Ensure athletes maintain proper form to mimic the rapid hip extension needed for high stride frequency.
Plyometrics: Integrate bounding, box jumps, and other explosive exercises to enhance hip extension power.
Hill Sprints: Incorporate uphill sprints to increase hip extension and strengthen the gluteus maximus and hamstrings. Uphill sprints simulate the high hip flexion and extension forces required for efficient sprinting.
Strength Training: Exercises such as squats, deadlifts, and hip thrusts will build foundational strength in the hip muscles, which are crucial for rapid leg swing and overall sprint performance.
Possible Coaching Cues:
Early Acceleration Phase (Below 7 m/s):
"Drive through the balls of your feet"
Encourage athletes to push through the balls of the feet during the stance phase to generate maximum vertical ground reaction force. This allows the ankle plantarflexors to produce the force necessary to propel the body upwards and forward, aiding in longer strides."Focus on a powerful push-off"
Emphasize the importance of a strong push-off with each step. This will help maximize the effectiveness of the plantarflexors (soleus and gastrocnemius) in generating the upward motion needed for longer strides.“Toes Up”
Encourage full ankle extension as the sprinter pushes off the ground and dorsiflexion prior to ground contact of the swing leg. A complete extension of the ankle maximises the length of each stride and contributes to the efficiency of the sprint.
Maximum Speed Phase (Above 7 m/s):
"Quick and powerful leg swings"
Encourage athletes to focus on fast leg swings and rapid leg turnover during the swing phase. The emphasis here is on accelerating the legs as quickly as possible during the swing, driven by the hip flexors and extensors."Drive your knees up and forward"
Instruct sprinters to focus on powerful knee drives to accelerate the legs faster. Engaging the iliopsoas (hip flexors) will facilitate this movement, helping to maintain higher stride frequencies while maintaining proper posture."Stay loose and relaxed"
Tight muscles can slow down leg turnover, especially at high speeds. Coaches should remind athletes to remain relaxed, particularly in the upper body, to ensure fluid and efficient movement. Tension in the arms, shoulders, and upper body can hinder the fast leg swings necessary at higher speeds.
Key Finding 2: The Importance of Dynamic Coupling
Dynamic coupling refers to the interconnectedness of muscle groups across the body during movement. This process explains how muscles that don't directly act on a joint can still contribute to its movement by transferring forces across body segments. This principle applies in sprinting, where the muscles on one side of the body not only perform their primary role but also help accelerate the movement of the opposite limb.
For example, during the sprinting swing phase, the hamstrings of the contralateral leg (the opposite leg) assist in extending the knee of the ipsilateral leg (the leg that is in the air and about to land). Even though the hamstrings do not directly span the knee joint of the ipsilateral limb, they play a role in its extension by creating a force across the body that contributes to the overall leg movement. This creates a more fluid and efficient motion during the sprinting cycle.
Understanding dynamic coupling enables coaches to see how the entire body is interconnected during sprinting, rather than focusing on individual muscles. Sprint mechanics are complex and require seamless coordination between the body’s muscle groups. When muscles on opposite sides of the body work together, they help generate greater force, improve stride efficiency, and reduce energy wastage. For example, effective coupling between the contralateral hamstrings and ipsilateral hip flexors or quads ensures smooth, rapid leg swings and a powerful stride.
For sprinters to maximise dynamic coupling, training should focus not just on individual muscle groups but on exercises that enhance the overall coordination between opposing muscle groups. This means that coaches should incorporate exercises that strengthen both the ipsilateral and contralateral muscles in ways that mimic sprinting mechanics. By training both sides of the body to work together more efficiently, sprinters can improve the speed of their leg swings and overall sprint performance.
Examples of Exercises:
Contralateral Lunges: These exercises encourage coordination between opposing muscles in the legs, helping to improve dynamic coupling and overall sprinting posture.
Single-leg Deadlifts or RDLs: These focus on strengthening the hamstrings and glutes while encouraging balance and muscle coordination across the body.
Plyometric Drills: Bounding, lateral hops, and other plyometrics enhance the ability of muscles to work in tandem across the body by stressing explosive movements.
Key Takeaway Messages
The muscular strategy shifts identified by Dorn, Schache, and Pandy (2012) provide essential insights for sprint training, particularly for sprinters. Coaches should focus on developing hip muscle strength and power to improve stride frequency and optimise sprint performance. By addressing these key muscular strategies and incorporating the appropriate exercises, coaches can help sprinters maximise their potential and achieve peak performance at high speeds.