Different Muscle Action Training Protocols on Quadriceps-Hamstrings Neuromuscular Adaptations

Area of Science:

• Sports Science
• Exercise Physiology
• Biomechanics

Background:

• Understanding neuromuscular adaptations to different training protocols is crucial for optimizing athletic performance and rehabilitation.
• Isokinetic training, utilizing concentric and eccentric muscle actions, is a common method for assessing and improving muscle function.

Purpose of the Study:

• To compare the effects of three distinct isokinetic training protocols (concentric/concentric, eccentric/eccentric, concentric/eccentric) on neuromuscular adaptations of the quadriceps and hamstrings.
• To investigate changes in muscle thickness, quality, activation, coactivation, and electromechanical delay following short-term training.

Main Methods:

• Forty male volunteers underwent 6 weeks of isokinetic training, with intensity and volume progressively increased.
• Participants were randomly assigned to concentric/concentric, eccentric/eccentric, concentric/eccentric, or control groups.
• Measurements of muscle thickness, quality, activation, coactivation, and electromechanical delay were taken before and after the training period.

Main Results:

• All training protocols significantly increased quadriceps and hamstrings muscle thickness (MT) compared to the control group.
• The concentric/eccentric (CON/ECC) and eccentric/eccentric (ECC/ECC) training groups showed a greater magnitude of change in MT.
• No significant differences were observed between groups for other neuromuscular variables assessed.

Conclusions:

• Short-term isokinetic training protocols involving different muscle actions lead to comparable increases in quadriceps and hamstrings muscle size.
• CON/ECC and ECC/ECC training protocols may yield superior muscle hypertrophy compared to CON/CON.
• Further research is needed to explore long-term effects and other neuromuscular adaptations.