The effect of ageing and exercise on skeletal muscle function

Area of Science:

• Skeletal muscle physiology
• Aging research
• Exercise science

Background:

• Skeletal muscle contractile and biochemical properties change with age.
• The impact of aging and exercise on these properties requires further investigation.

Purpose of the Study:

• To investigate the effects of aging and regular exercise on the contractile and biochemical properties of fast- and slow-twitch skeletal muscles in rats.
• To determine how aging influences muscle relaxation time, tension, shortening velocity, and fatigue.

Main Methods:

• Comparison of fast- and slow-twitch skeletal muscles from rats at 9, 18, and 28 months of age.
• Assessment of isometric twitch duration, one-half relaxation time (1/2RT), peak tension (Po), rate of tension development/decline, maximal shortening velocity, and muscle fatigue.
• Biochemical analysis of sarcoplasmic reticulum Ca2+ uptake, glycogen, and lactate levels.

Main Results:

• Isometric twitch duration and 1/2RT were prolonged with aging, particularly in slow-twitch muscle, developing late in life.
• Twitch/tetanic tension (Po), peak tension rates, and maximal shortening velocity remained unchanged with age and exercise.
• Muscle fatigue was not affected by aging, but aged rats showed increased glycolysis and glycogen utilization.

Conclusions:

• Aging significantly alters skeletal muscle relaxation properties, but not maximal force or velocity.
• Regular exercise demonstrated limited effects on age-related changes in muscle contractile function.
• Aged rats exhibit altered metabolic responses during contractile activity, suggesting increased reliance on glycolysis.