This study evaluates whether resistance exercise will improve immune responses to the seasonal influenza vaccine in older adults. One third of the participants will perform exercise in the arm that receives the vaccine, one third of the participants will perform the same exercise in the arm that does not receive the vaccine, and one third will only receive the vaccine.

Resistance exercise, particularly novel eccentric exercise, recruits immune cells to the targeted muscle. The exercises selected here targets the deltoid and biceps brachii muscles-those same muscles that the flu vaccine is delivered to during typical vaccination.

Inclusion Criteria:

• non-frail older adult (≥65 years old) of any sex and race/ethnicity
• non-smokers (>10 yrs)
• meets American College of Sports Medicine criteria for participation in exercise
• US resident

Exclusion Criteria:

• underlying medical problems that contraindicate supervised resistance exercise
• past or present history of autoimmune disease, HIV, hepatitis, stroke, or cardiovascular disease
• current debilitating arthritis of the shoulder
• central or peripheral nervous disorders
• bedridden in the past three months
• history of vaccine-related allergies, or severe egg allergy;
• physician-confirmed influenza infection in the prior year
• regular user of corticosteroids
• functional or cognitive impairment that would limit exercise performance or prohibit informed consent
• blood pressure greater than 160/90
• participation in resistance arm exercises in the prior 6 months

De-identified individual participant data for all primary and secondary outcome measures will be made available.

Data will be available within 6 months of study completion.

Data access requests will be reviewed by an external independent review panel. Requestors will be required to sign a Data Access Agreement.