Resistance Exercise and Low-Intensity Physical Activity Breaks in Sedentary Time to Improve Muscle and Cardiometabolic Health

Although awareness of the detrimental impact that sedentary behavior has on skeletal muscle and cardiometabolic health has increased over the last 20 years, more than 60% of older adults remain sedentary for greater than 8 hours per day. Moreover, 80% to 90% of adults 60 years of age or older do not meet the current public health guidelines for aerobic exercise (AE) or resistance exercise (RE) based physical activity (PA). Collectively, these adverse health behaviors contribute to the development of multiple chronic medical conditions commonly afflicting older adults, including type 2 diabetes, cardiovascular disease, sarco/dynapenia, frailty, and premature mortality. Emerging evidence suggests that breaking up sedentary time with light intensity PA (LPA) improves muscle and cardiometabolic health. Recent data also suggest that RE combined with moderate intensity AE effectively improves muscle and cardiometabolic health in older adults. However, the impact that RE combined with LPA breaks in sedentary time has on muscle and cardiometabolic health in older adults remains unknown. The overall objective of this pilot study is to determine the effect of 16 weeks of RE alone or RE combined with LPA breaks in sedentary time on muscle and cardiometabolic health.

Inclusion criteria

• Are capable and willing to give written informed consent, and understand exclusion criteria
• 65-80 years of age inclusive
• Body Mass Index (BMI) between 18.5-34.9 kg/m2, inclusive
• Physically inactive determined by self-report
• Stable medical therapy for allowable medications for 30 days defined as:

• No addition or removal of a medication
• No change in dosage of a medication
• Having no life-threatening conditions or diseases
• Willing to allow researchers to use data, bio-specimens (blood and muscle tissue), and images (e.g., magnetic resonance imaging) for research purposes after study participation is completed
• At least 2 weeks post-completion of the COVID19 vaccine regimen. a. Acceptable proof of vaccine includes a completed vaccine card and/or letter from a healthcare provider indicating the date that the COVID19 vaccine was completed.

Exclusion criteria

• Nursing home resident
• Physically Active:

a. > 100 min/wk of moderate OR > 50 min/wk vigorous intensity PA

• Saint Louis University Mental State (SLUMS) score < 21
• Evidence or self-report history of deep vein thrombosis, pulmonary embolism, cardiovascular, peripheral vascular, cerebral vascular, pulmonary, or renal disease
• Evidence or self-report history of type 1 or 2 diabetes mellitus
• Evidence or self-report history of a bleeding disorder
• Evidence or self-report history of recurrent vasovagal episodes
• Evidence or self-report history of severe depression, Schizophrenia, bipolar disease
• Evidence or self-report history of mobility disability requiring a walker, wheel chair, or inability to walk across a small room.
• Evidence or self-report history of orthopedic limitations that would preclude them from participation in a dynamic exercise program
• Evidence or self-report history of severe arthritis (either osteoarthritis or rheumatoid arthritis) that would preclude them from participation in a dynamic exercise program
• Evidence or self-report of history untreated thyroid dysfunction.
• Weight loss of > 10% in the last 3 months prior to screening
• History of weight loss surgery.
• Use of medications known to influence study outcomes, such as:

• Insulin
• Oral antidiabetic medications (e.g., metformin)
• Corticosteroids
• Beta-blockers

c. Anticoagulants

• Allergy to lidocaine
• Active smoking
• Current consumption of > 14 alcoholic drinks per week based on self-report
• Regular participation in resistance or aerobic exercise training within 3 months of initial screening
• Absolute Contraindication to Exercise as Defined by the American College of Sports Medicine,16 including:

• Resting diastolic blood pressure > 100 mm Hg
• Resting systolic blood pressure > 180 mm Hg
• Resting heart rate > 100 beats per min
• Having a body weight greater than 440 pounds
• Having medical implants such as a pacemaker or metal joint replacements
• Having tattoos or permanent makeup completed <30 days prior to the visit
• Recent (past 3 months) cancer diagnosis, undergoing immunotherapy, taking immune suppressants
• Presence of allergies or infections requiring antibiotics within the past 14 days
• Recent (past 3 months) major surgery on the abdomen, pelvis, or lower extremities
• Any other condition that in the judgement of the Principal Investigator and/or the Medical Director of this protocol may interfere with study participation and adherence to the protocol.
• Evidence or self-report history of severe depression in the last 5 years.