Use of Exercise Snacks to Improve Upper Body Fitness

The academic demands imposed on graduate students present a barrier to performing regular resistive exercise and promote a sedentary lifestyle, which can lead to losses in upper-body strength, power, and endurance.

There are many causes of loss of lean body mass (LBM) in the general population. Decreases in strength and LBM typically begin between thirty and forty years of age and progress at a rate of 3-10% per decade. After the age of 70, the rate of LBM loss and strength decline accelerates to approximately 3% per year. These changes may be attributed to immobilization, loss of appetite, muscular dystrophies, chronic disease, aging, and sedentary behavior. By age 65, difficulty with dressing, transferring, walking, and toileting occurs at rates between 14% and 17%. By age 75, the incidence of difficulty increases to between 20% and 27%, and by age 85, difficulty with dressing, bathing, walking, toileting, and transferring increases to between 26% and 36%. Decreases in LBM and strength are strong indicators of negative health outcomes and represent one of the primary contributors to sarcopenia, alongside anorexia, dehydration, and cachexia. Loss of LBM combined with obesity further increases the risk of developing type II diabetes due to the role of skeletal muscle in glycemic control. Reductions in LBM also negatively affect bone density and metabolic rate.

Resistance training is one of the most effective interventions for improving physical performance and long-term health across the lifespan. Resistance training enhances muscular strength, endurance, and neuromuscular control, all of which are essential for optimal movement, joint stability, and performance of daily functional activities. Resistance exercise stimulates muscle hypertrophy, improves motor unit recruitment, increases LBM, and supports metabolic health through improved insulin sensitivity and elevated resting metabolic rate.

In older adults, resistance training increases muscle mass, strength, and power, while reducing difficulty performing daily activities and supporting independence with aging. Moderate-intensity, short-term resistance training significantly improves insulin sensitivity and HbA1c levels in older adults. In older women, resistance training reduces age-related declines in cortical bone health and bone mineral density of the hip and spine. Resistance training also reduces mild to severe depressive symptoms, thereby improving quality of life across age groups.

The American College of Sports Medicine (ACSM), American Heart Association (AHA), National Institutes of Health (NIH), and National Health Service (NHS) recommend performing resistance exercises at least twice per week for all major muscle groups, including the legs, hips, back, chest, abdomen, shoulders, and arms. These exercises are generally recommended at moderate intensity, characterized by muscular fatigue after completing 12-15 repetitions.

Despite the known benefits of resistance exercise, many individuals face barriers to consistent participation. Physical limitations associated with aging, chronic health conditions, psychological factors (e.g., lack of motivation, fear of injury, embarrassment), limited transportation, financial constraints, and environmental factors such as weather can all negatively affect adherence.

Among graduate students, time constraints related to academic workload are a primary barrier to regular resistance exercise and promote sedentary behavior. Previous studies have demonstrated declines in fitness and exercise participation during graduate training. Limited institutional support for physical activity and financial constraints further exacerbate barriers to consistent resistance training.

A potential solution to declining fitness among graduate students is the integration of resistive "exercise snacks" (ES). Exercise snacks are brief bouts of exercise lasting 1-5 minutes, separated by short rest periods, and performed multiple times per day. These sessions can be completed as little as three times per week.

Current literature strongly supports the viability of the ES approach. A 2024 systematic review by Yin et al. examining 11 randomized controlled trials found that ES protocols improved strength, flexibility, and balance in older adults without requiring equipment, while reducing common barriers such as time constraints and access limitations. Additional randomized trials have demonstrated improvements in cardiorespiratory fitness, muscular strength, power, and adherence using minimal-volume ES protocols across diverse populations.

Collectively, the literature supports ES as a time-efficient and effective training strategy for improving muscular and cardiovascular outcomes while enhancing adherence among populations facing barriers to traditional exercise. However, research examining upper-body resistance-based ES in young adult populations remains limited.

The objective of this study is to determine the effects of a six-week upper-body ES program performed at submaximal intensities on upper-body strength, power, endurance, participant retention, adherence, and satisfaction. The study aims to determine whether short-duration, repeated submaximal ES performed multiple times per day, three days per week, elicits positive adaptations in upper-body muscular performance among graduate students who do not regularly engage in resistance training.

It is hypothesized that the ES group will demonstrate greater improvements in upper-body strength and endurance compared to a control group maintaining usual physical activity. A secondary hypothesis is that outcomes in the ES group will not differ from those observed in a maximal-intensity, once-daily resistance exercise group performing the same exercises three days per week. A third hypothesis is that the ES group will demonstrate greater participant retention, adherence, and satisfaction compared to the maximal-intensity exercise group.

Investigating the effects of upper-body resistive ES on muscular performance in graduate students may identify an accessible, time-efficient, and lower-effort training strategy capable of improving strength, power, and adherence despite substantial academic demands.