Arthritis Pilot for Preserving Muscle While Losing Weight

The loss of muscle mass and bone density during weight loss is partially attributed to the decrease in mechanical stress on these tissues as weight is reduced. As a result, performing exercises that enhance muscle and gravitational loading during the period of caloric restriction usually diminishes the relative amount of muscle and bone loss for a given weight loss, but these interventions do not fully prevent all muscle and bone loss.In addition, conventional exercise training interventions often require expensive equipment, on-site participation, and, ideally for older, obese adults, safety supervision by trained exercise leaders. Moreover, the exercises performed may not fully translate into improvement in daily tasks due to training specificity, and are not always tolerated or sustained, especially in obese persons with OA. On the other hand, it is conceivable that treating the decrease in mechanical load from weight loss by externally replacing lost weight via use of a weighted vest may also be effective for reducing muscle and bone loss during caloric restriction. In animal models, mechanisms regulating skeletal tissue structure and function respond in a similar fashion to increases in actual or externally-added body mass. Also, research shows that exercising while wearing weighted vests can improve bone density, muscle mass, and lower extremity strength in older adults. However, no prior studies have examined the effects of weighted vest use on muscle mass and bone density during a period of intentional weight loss.

The main objective of this pilot study is to assess feasibility (accrual, retention, compliance) of daily use of a weighted vest during a diet intervention, to estimate the variability of outcome measures, and to obtain preliminary estimates of treatment efficacy. A controlled, randomized design will be used so we can obtain a realistic estimate of accrual and an unbiased estimate of treatment efficacy.

A total of 36 older (age=65-79 yrs), obese (BMI=30-40 kg/m2), sedentary men and women with x-ray evidence of knee OA will undergo a 22 week weight loss intervention (targeting 10% weight loss) with randomization to one of two groups (n=18/grp): 1) No vest use (Control); or 2) Progressive weighted vest use during normal daily activities (VEST).

Inclusion criteria

• BMI=30-40 kg/m2; Wt<135 kg,
• self- reported MD diagnosis of osteoarthritis
• No evidence of clinical depression or other contraindications for participation in voluntary weight loss,
• Sedentary lifestyle (<30 min, 3 d/wk of exercise),
• Able to provide own transportation to study visits and intervention,
• Not dependent on a cane or walker,
• Willing and able to consume meal replacement products,
• Not involved in other research study,
• Approved for participation by Medical Director,
• Willing to provide informed consent.

Exclusion criteria

• Weight loss or gain (±5%) in past 6 mos,
• Excessive alcohol use (> 14 drinks/wk),
• Smoker (>1 cigarette/d or 4/wk within yr),
• Evidence of cognitive impairment (MoCA score <22) or difficulty with hearing or vision that would interfere with study participation, Insulin-dependent or uncontrolled diabetes (FBG >125 mg/dl) or Hypertriglyceridemia (TG>400 mg/dl),
• Osteoporosis (T-score< -2.5 on hip or spine); Hip fracture, joint replacement, or spinal surgery in past 6 mos, or hyperkyphosis,
• Uncontrolled hypertension (BP>160/90 mmHg) or abnormal kidney or liver tests per Medical Director discretion,
• Self- reported hepatitis B or C,
• Severe anemia (Hb<10 g/100 ml),
• Past or current uncontrolled endocrine/metabolic disease, neurological or hematological disease, fibromyalgia, chronic pulmonary disease, hyperparathyroidism, rheumatoid arthritis, unstable angina, MI, cardiac surgery within 3 months,
• Cancer requiring treatment in past year except non-melanoma skin cancers,
• Regular use of medications that may influence body weight, hormones, weight loss medications, bone remodeling medication, prior use of medications that affect bone, insulin-dependent,
• Unable to tolerate vest run-in.