Weakness, SR function and stress in gastrocnemius muscles of aged male rats.

Aging is associated with a decline in muscle force that exceeds loss of muscle mass, suggesting that factors other than sarcopenia affect age-related muscle weakness. Here, we investigate in situ muscle force and sarcoplasmic reticulum (SR) properties in gastrocnemius muscles of adult (6-8 months) and aged (24 months) rats. Despite minimal loss of muscle mass, peak tetanic force was significantly reduced (-28%) in aged muscles.

"SR stress" in mixed hindlimb muscles of aging male rats.

Impaired sarcoplasmic reticulum (SR) function has been associated with reduced muscle force generation and locomotor function in aging animals. This study was conducted to determine the extent to which aging increased SR stress markers in male rats, and the extent to which volitional exercise affected them. We harvested medial gastrocnemius muscles from F344/BN rats that were adult (8 months; n = 8), aging (24 months; n = 8) and that aged with wheel access for 16 months (24 months; n = 4).

Development of a neuromuscular electrical stimulation protocol for sprint training.

Purpose: Sprint training is associated with several beneficial adaptations in skeletal muscle, including an enhancement of sarcoplasmic reticulum (SR) Ca(2+) release. Unfortunately, several patient populations (e.g.