31 May Immobility and The Power of Muscle Training

Every muscle cell lives for the entire life of its individual. New cells are produced after trauma. Muscle fibers are capable of healing through a process of regeneration. They can recover in the exact same way as they were prior to the damage.

Muscle metabolic turnover is rapid, in adult’s muscles can regenerate in 7-15 days. This is seen how quick muscle can adapt i.e. grow after new mechanical requirements, weight lifting for example. This is because they are biologically very busy, have a generous blood supply, nutrients and energy.

Training – the maximum weight that can be lifted during weight training exercises can be increased by 100% in twelve months firstly due to increased endurance and improved neuromuscular activation efficiency and therefore increased proportion of fibers that can fire at one time and secondly hypertrophy, or growth of the muscle in adaptation to the training.

Conversely, inactivity and immobility reduce muscle mass. Within hours a decrease in protein synthesis can be demonstrated. Muscles that are immobilized, often in shortened positions, decrease in length and girth. Bones become stiffer and lose extensibility. Complete immobilization of the leg for 6 weeks can reduce the size of the quadriceps muscle by up to 20%.

Facts:

• Muscle protein syntheses decreases within 6 hours of total immobilisation
• Two weeks of cast immobilization decreases muscle fiber size
• As myofibrils degenerate fibrous and fat tissue become progressively larger
• Six weeks of cast immobilization can decrease the weight of animal muscle nearly 25% and after 22 weeks 70%
• In humans, 6 weeks forearm cast immobilisation reduced adductor pollicus longus voluntary contraction by 55%

Endurance training performed for 30-60 mins increases the capacity of muscles for sustained effort. It increases the number and size of muscle cell mitochondria, muscle glycogen concentrations and the proportion of muscle cells identified as having oxidative capacity can double.

Strength training using high tension, low repetition muscle activity increases muscle strength and volume primarily by causing hypertrophy or growth. The muscle cell grows by scrutinizing requirements and producing more myofibrils, the contractile element of the cell, and hence it enlarges due to perceived greater need for same.

Start easy and build slowly.