Bed rest can spell disaster for elderly people whose muscle mass is declining. A couple of days in bed – say during a bout of flu – can cost valuable kilograms of muscle, which may mean the difference between being able to live independently and having to rely on help. HMB can help write researchers at the University of Arkansas soon in Clinical Nutrition.
The researchers used a total of 19 men and women subjects aged between 60 and 76. The elderly subjects had to lie in bed for 10 days, after which they were given rehabilitation for eight weeks in the form of strength training. Eight people took a placebo for the duration of the experiment; eleven took 3 g calcium HMB each day. The subjects took their HMB in two doses of 1.5 g divided over the day. Supplementation started five days before the subjects had to retire to bed and stopped at the end of the rehabilitation period.
The subjects were given a diet that provided 0.8 g protein per kg bodyweight daily.
Taking the supplement during the period of bed rest reduced the breakdown of muscle mass and the decline in muscle power in the legs The researchers assessed muscle power by measuring the strength the subjects managed to develop on a leg extension machine as their knee joint made an angle of 60 and 180 degrees.
The subjects that were taking HMB reacted better to the strength training after the bed rest.
The researchers studied the production of muscle tissue [in this case the FSR] in the subjects by examining samples of muscle tissue from their legs. Production was higher in the subjects that had received HMB, but the difference between the experimental subjects and those in the control group was not significant.
“HMB is an effective nutritional intervention for preservation of muscle mass in healthy older adults confined to bed rest”, the researchers conclude. “It may be that a greater availability of essential amino acids was required than we provided, by using the RDA as a guideline for protein intake, for a stimulatory effect of HMB on muscle FSR to reach statistical significance.”
“In that light, an effective therapeutic regimen for preventing muscle decline over extended hospitalization may involve a combination approach of using HMB plus essential amino acids (or a high quality protein source that provides essential amino acids) and possibly vitamin D to effectively preserve muscle mass, strength and function.”
The study was financed by Abbott Nutrition, a manufacturer of supplements and clinical nutritional products.
Effect of ?-hydroxy-?-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults
Loss of muscle mass due to prolonged bed rest decreases functional capacity and increases hospital morbidity and mortality in older adults.
To determine if HMB, a leucine metabolite, is capable of attenuating muscle decline in healthy older adults during complete bed rest.
A randomized, controlled, double-blinded, parallel-group design study was carried out in 24 healthy (SPPB ? 9) older adult subjects (20 women, 4 men), confined to complete bed rest for ten days, followed by resistance training rehabilitation for eight weeks. Subjects in the experimental group were treated with HMB (calcium salt, 1.5 g twice daily – total 3 g/day). Control subjects were treated with an inactive placebo powder. Treatments were provided starting 5 days prior to bed rest till the end rehabilitation phase. DXA was used to measure body composition.
Nineteen eligible older adults (BMI: 21–33; age: 60–76 year) were evaluable at the end of the bed rest period (Control n = 8; Ca-HMB n = 11). Bed rest caused a significant decrease in total lean body mass (LBM) (2.05 ± 0.66 kg; p = 0.02, paired t-test) in the Control group. With the exclusion of one subject, treatment with HMB prevented the decline in LBM over bed rest ?0.17 ± 0.19 kg; p = 0.23, paired t-test). There was a statistically significant difference between treatment groups for change in LBM over bed rest (p = 0.02, ANOVA). Sub-analysis on female subjects (Control = 7, HMB = 8) also revealed a significant difference in change in LBM over bed rest between treatment groups (p = 0.04, ANOVA). However, differences in function parameters could not be observed, probably due to the sample size of the study.
In healthy older adults, HMB supplementation preserves muscle mass during 10 days of bed rest. These results need to be confirmed in a larger trial.