Triceps Surae Muscle Architecture Adaptations to Eccentric Training.

Area of Science:

• Exercise Physiology
• Muscle Adaptation
• Biomechanics

Background:

• Eccentric exercise is integral to physical training, injury prevention, and rehabilitation.
• Eccentric training induces specific skeletal muscle morphological adaptations.
• Synergistic muscles, like the triceps surae, may exhibit varied adaptations due to architectural and functional differences.

Purpose of the Study:

• To investigate the effects of a 12-week eccentric training program on the muscle architecture of the triceps surae.
• To compare adaptations in the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and soleus (SO) muscles.

Main Methods:

• Twenty healthy males participated in a 12-week eccentric training program.
• Muscle architecture parameters (fascicle length, pennation angle, muscle thickness) were assessed via ultrasonography every 4 weeks.
• Evaluated muscles included the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and soleus (SO).

Main Results:

• Eccentric training led to significant increases in fascicle length (GM: 13.2%, GL: 8.8%, SO: 21%) and muscle thickness (GM: 14.9%, GL: 15.3%, SO: 19.1%).
• Pennation angles remained largely unchanged post-training.
• The soleus (SO) muscle exhibited the greatest increase in fascicle length, while the gastrocnemius lateralis (GL) showed the smallest gains.

Conclusions:

• Eccentric training promotes hypertrophy and fascicle elongation in all three synergistic plantar flexor muscles.
• Muscle thickness increased uniformly across the GM, GL, and SO.
• The soleus muscle, characterized by its shorter baseline fascicle length, demonstrated a proportionally larger fascicle length adaptation.