Journal Title (Medline/Pubmed accepted abbreviation): New Engl. J. Med.
Page numbers: 1218-1229
doi (if applicable):
Summary of Background and Research Design
Background: Older adults are more susceptible to health problems such as cardiovascular disease and osteoporosis due to decreased physical functions. These symptoms are exacerbated by obesity. There are only a few studies to date investigating the risks and benefits of diet and/or exercise intervention in the overweight, elderly population.
Hypothesis/Research Question: Weight loss and exercise would improve physical function (strength, balance, cardiovascular function) and the combination of weight loss and exercise would have the greatest effect.
Subjects: Subjects were older than 65 yrs old, had a BMI or 30 or greater, and were not involved in a regular exercise routine. Ninety three subjects completed the study.
Experimental design: random assignment to 1 of 4 groups, as listed below, for 52 wks (1 yr)
- Control group- Participants maintained their lifestyle and were provided with information on a healthy diet with no goals to lose weight.
- Diet group- Subjects were asked to follow a diet with a 500-700 kcal energy deficit. The goal was to lose 10% of their initial body weight in the first 6 mos. and then maintain that weight for the second half of the study.
- Exercise group- These subjects participated in 90 min group exercise sessions 3x/wk that consisted of aerobic, strength, flexibility, and balance exercises. A diet plan was recommended that would help them maintain their current weight.
- Diet-exercise group- These participants followed both the diet and the exercise protocols as listed above.
Protocol: These parameters were measured at baseline, 6 mos, and 12 mos: the Physical Performance Test (7 standardized tasks including walking 50 ft, donning and doffing a coat, picking up a penny, standing from being seated in a chair, lifting a book, climbing one flight of stairs, and performing a progressive Romberg test which assesses balance; they received a score from 0 to 36 with higher scores indicating better physical status); specific physical measures such as VO2max, gait speed, one repetition maxima on certain exercises, body composition; bone mineral density; and quality of life.
Summary of research findings:
- There was an increase in the outcome of the Physical Performance Test for the diet-exercise group (5.4 ± 2.4 pts), the diet group (3.4 ± 2.4 pts), and the exercise group (4.0 ± 2.5 pts). These improvements were 21%, 12%, and 15% greater, respectively than the increase in the placebo group (P < 0.001 for the between-group differences).
- The VO2max increased the most for the diet-exercise group (3.1 ± 2.4 mL/kg/min; 17%) followed by the diet group (1.7 ± 2.3 mL/kg/min; 10%) then the exercise group (1.4 ± 1.0 mL/kg/min; 8%).
- Those in the diet group lost 10% of their initial weight and those in the diet-exercise group lost 9% of their initial weight. Those in the exercise and the control groups lost < 1% body weight on average.
- The exercise group experienced a 2% increase in lean body mass and a 1.5% increase in bone mineral density at the hip. Those in the diet-exercise group lost 3% lean body mass on average and 1.1% bone mineral density at the hip. The losses of lean body mass and bone mineral density in the diet and exercise group were less than the losses that the diet group experienced: a loss of 1.8 ± 1.7 kg lean body mass (3%) and 2% in bone mineral density.
- One-repetition maxima for biceps curl, bench press, seated row, knee extension, knee flexion, and leg press increased for the exercise and diet-exercise group and was maintained for the control and the diet groups.
- Gait speed increased in the exercise group 14% and the diet-exercise group 23%.
- The physical-component summary score which is used to measure quality of life increased 15% in the diet-exercise group, 14% in the diet group, and 10% in the exercise group.
Interpretation of findings/Key practice applications:
Both weight loss and exercise are effective at increasing physical function (walking, strength, balance, performing everyday tasks, etc.) and the combination of both weight loss and exercise is the most effective. The improvements observed may help seniors maintain their independence and reduce their risks of accidents, disability, and complications from chronic diseases.