The effects of oral amino acid intake on ambulatory capacity in elderly subjects.
OBJECTIVE
The combination of high prevalence of inactivity in the older population, and high risk of ill-health and disability associated with inactivity, suggests that interventions that are successful in increasing levels of activity may have a great impact on population health in later life. With advancing age, the risk of developing serious nutritional deficiencies also increases. This study was designed to assess the effects of dietary amino acid supplementation on effort tolerance in healthy elderly subjects with reduced physical activity.


METHODS
Forty-four subjects (age > 65 years) with sedentary life-style and lower health-related quality of life were studied. Subjects, in an open-label fashion, received an oral amino acid mixture (AAM, 12 g/day) containing essential and non-essential amino acids for a 3-month period. Ambulatory dysfunction resulting in sedentary life-style was assessed by a 6-min walk test. A walking impairment questionnaire (WIQ) was used to evaluate self-perceived ambulatory dysfunction. Maximal isometric muscular strength of the right hand was measured during isometric exercise by a handgrip dynamometer.


RESULTS
The 6-min walk distance increased from 214.5 +/- 32 to 262.8 +/- 34.8 m (p < 0.001) after AAM treatment. The baseline scores on the three subscales of WIQ changed significantly during treatment: WIQ distance increased from 56.2 +/- 12.9 to 66.3 +/- 12.8% (p < 0.001); WIQ speed from 52 +/- 12.6 to 69.2 +/- 14.8% (p < 0.001) and WIQ stairs from 74.4 +/- 22.6 to 94.2 +/- 25% (p < 0.001), as did maximal isometric muscular strength (16.6 +/- 2.4 vs 19.2 +/- 2.2 kg, p < 0.001). Changes in plasma glucose (+11 +/- 11 mg/dL), total cholesterol (0 +/- 39 mg/dL), HDL cholesterol (0 +/- 17 mg/dL), and triglycerides (-11 +/- 58 mg/dL) were not significant between baseline and AAM.


CONCLUSIONS
An oral amino acid supplement, as used in this pilot study, improves ambulatory capacity and maximal isometric muscle strength in elderly subjects without affecting the main metabolic parameters. Amino acid supplementation may thus represent useful non-pharmacological intervention to maintain physical fitness in these subjects.
Scognamiglio
Roldano
R
Division of Metabolic Diseases, University of Padova, Padova, Italy. r.scognamiglio@unipd.it
Avogaro
Angelo
A
Negut
Christian
C
Piccolotto
Roberto
R
de Kreutzenberg
Saula Vigili
SV
Tiengo
Antonio
A
D000284:Administration, Oral; D000368:Aged; D000596:Amino Acids / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D008297:Male; D009132:Muscles / Q000187:drug effects* / Q000502:physiology* / Q000503:physiopathology; D013997:Time Factors; D016138:Walking / Q000502:physiology*
D000596:Amino Acids