Training and Detraining Effects of Eccentric Exercise and Static Stretching on Hamstring Aponeurosis Dimensions

Area of Science:

• Sports Medicine
• Exercise Physiology
• Anatomy

Background:

• Muscle-tendon unit adaptations are crucial for athletic performance.
• Understanding how different training modalities affect connective tissues and muscle size is important for optimizing training programs.

Purpose of the Study:

• To compare the effects of eccentric knee-flexor training and static stretching on hamstring aponeurosis dimensions and muscle size.
• To investigate the reversibility of these changes after a detraining period.

Main Methods:

• Eleven healthy untrained men underwent 10 weeks of unilateral eccentric training or static stretching.
• Magnetic resonance imaging (MRI) was used to quantify hamstring aponeurosis and muscle volumes.
• A 4-week detraining period followed the intervention.

Main Results:

• Both eccentric training and static stretching significantly increased hamstring outer and inner aponeurosis dimensions.
• Muscle hypertrophy was observed only following eccentric training, particularly in biarticular hamstrings.
• Aponeurosis adaptations were maintained during detraining, while muscle hypertrophy decreased but remained above baseline.

Conclusions:

• Hamstring aponeurosis dimensions can be enhanced through both eccentric loading and static stretching.
• Muscle hypertrophy is primarily an adaptation to eccentric exercise and is more susceptible to short-term detraining.
• Aponeurosis and muscle size changes appear to be independent adaptations to these training modalities.