Active and Passive Immunity. Naturally acquired active immunity occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response. Artificially acquired active immunity can be induced by a vaccine, a substance that contains the antigen.
Lower back tightness can cause muscle twitching, pain and reduced range of motion. Lower back muscle tightness is the cause of a muscle spasm. This can be brought on by a strain, overuse or muscle weakness, according to BetterMedicine.com.
Hot spots for tightness are the neck, shoulders, and back. Clenching your muscles out of stress or anxiety can create knots, or they can develop due to an injury, poor posture, or even long periods of inactivity. RELATED: The Best Post-Workout Stretches. Massage is in fact one of the best ways to release the tension.