Running training alters fiber type composition in spinal muscles

Area of Science:

• Exercise physiology
• Muscle biology
• Canine research

Background:

• The impact of exercise on muscle fiber type adaptation is a well-established concept.
• However, research specifically investigating changes in spinal muscle fiber types remains limited.

Purpose of the Study:

• To investigate the effects of long-distance running on muscle fiber type distribution in canine spinal and limb muscles.
• To determine if endurance training can induce shifts in fiber type composition and oxidative capacity in stabilizing muscles.

Main Methods:

• Ten young dogs underwent a 55-week treadmill running program with gradually increasing distance.
• Control group of ten dogs received no specific exercise regimen.
• Histological analysis of multifidus (spinal) and triceps brachii (limb) muscles for fiber type composition and cross-sectional area.
• Nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) staining to assess oxidative capacity.

Main Results:

• Endurance running led to a significant increase in type II (low oxidative capacity) fibers in the lumbar multifidus.
• A shift from type II to type I (high oxidative capacity) fibers was observed in the thoracic and cervical multifidus, and triceps brachii.
• NADH-TR analysis indicated enhanced oxidative capacity within type II fibers in the trained group.

Conclusions:

• Endurance training induces significant changes in muscle fiber type composition in both limb and stabilizing spinal muscles.
• These adaptations include shifts towards fibers with higher oxidative capacity, demonstrating muscle plasticity in response to prolonged exercise.
• The findings suggest that stabilizing spinal muscles are adaptable to endurance training, similar to limb muscles.