Training for endurance and strength: lessons from cell signaling

Area of Science:

• Exercise physiology
• Molecular biology
• Sports science

Background:

• Concurrent training, exercising for strength and endurance simultaneously, leads to reduced adaptation compared to isolated training.
• Resistance exercise promotes muscle hypertrophy, while endurance exercise enhances mitochondrial and capillary adaptations.
• Recent advances offer molecular explanations for the concurrent training effect.

Purpose of the Study:

• To explain the molecular mechanisms behind the concurrent training effect.
• To investigate the roles of specific protein kinases in mediating exercise adaptations.
• To identify how these pathways interact and potentially interfere with each other.

Main Methods:

• Review of molecular signaling pathways involved in muscle adaptation to exercise.
• Focus on the roles of Protein Kinase B (PKB/Akt) and AMP-activated protein kinase (AMPK).
• Analysis of how these kinases regulate protein synthesis, breakdown, and mitochondrial adaptations.

Main Results:

• PKB/Akt activation promotes muscle hypertrophy by increasing protein synthesis and decreasing breakdown.
• AMPK activation enhances endurance adaptations, including increased mitochondrial protein and glucose transport.
• PKB and AMPK signaling pathways antagonistically interfere with each other's downstream effects.

Conclusions:

• The concurrent training effect is explained by the molecular blockade between PKB and AMPK signaling.
• This molecular antagonism hinders the simultaneous development of both strength and endurance phenotypes.
• Understanding these interactions can inform the design of optimized training programs for maximal strength and endurance gains.