Human skeletal sarcoplasmic reticulum Ca2+ uptake and muscle function with aging and strength training

Area of Science:

• Exercise physiology
• Skeletal muscle biology
• Aging research

Background:

• Elderly individuals often experience muscle function decline, including slower relaxation and reduced calcium handling.
• Sarcoplasmic reticulum (SR) Ca2+ uptake and Ca2+-ATPase activity are critical for muscle relaxation.
• Differences in skeletal muscle adaptations to resistance training between young and elderly women are not fully understood.

Purpose of the Study:

• To compare skeletal muscle sarcoplasmic reticulum (SR) Ca2+ uptake, relaxation, and fiber type adaptations to high-resistance training in young and elderly women.
• To determine if resistance training can reverse age-related declines in SR Ca2+ handling and muscle relaxation.
• To investigate the relationship between SR Ca2+ uptake and muscle relaxation speed in older adults.

Main Methods:

• Assessed quadriceps femoris muscle relaxation time and rate in young and elderly women.
• Measured maximal rates of SR Ca2+ uptake and Ca2+-ATPase activity from vastus lateralis muscle biopsies.
• Compared pre- and post-training adaptations in young women (YW) and elderly women (EW) after 12 weeks of high-resistance training.

Main Results:

• Elderly women exhibited slower relaxation, decreased SR Ca2+ uptake, and lower Ca2+-ATPase activity compared to young women.
• High-resistance training significantly increased SR Ca2+ uptake and Ca2+-ATPase activity in elderly women (EWT).
• Resistance training did not alter relaxation speed or fiber type distribution in either young or elderly women.

Conclusions:

• Reduced SR Ca2+ uptake in elderly women's skeletal muscle can be partially improved by resistance training.
• SR Ca2+ uptake in the vastus lateralis is not the sole determinant of slower quadriceps muscle relaxation in elderly women.
• Age-related impairments in muscle relaxation may involve mechanisms beyond SR Ca2+ uptake rate.