Identification and comparison of the predictors of maximal inspiratory force and handgrip in a healthy elderly population. The proof study

Relationship between respiratory muscle strength and grip strength in institutionalized and community-dwelling older adults

OBJECTIVE: To evaluate the relationship between respiratory muscle strength and grip strength in institutionalized and community-dwelling older adults. METHODS: This cross-sectional study had 64 voluntary participants, and 33 were institutionalized and 31 lived in the community. Maximal inspiratory pressure, maximal expiratory pressure, peak expiratory flow, grip strength, anthropometric data, and physical activity level were assessed. RESULTS: In the institutionalized group, there was no correlation between respiratory variables and grip strength, but maximal expiratory pressure was the respiratory predictor most strongly associated with grip strength (p = 0.04). In the community-dwelling group, there was a correlation between maximal inspiratory pressure and grip strength (r = 0.54), maximal expiratory pressure and grip strength (r = 0.62), and peak expiratory flow and grip strength (r = 0.64); peak expiratory flow and maximal expiratory pressure were the respiratory predictors most strongly associated with grip strength (p < 0.05). In a joint group analysis, there was an association between maximal inspiratory pressure and grip strength (r = 0.40), maximal expiratory pressure and grip strength (r = 0.57), and peak expiratory flow and grip strength (r = 0.57); peak expiratory flow and maximal expiratory pressure were the respiratory predictors most strongly associated with grip strength (p < 0.05). CONCLUSIONS: Peak expiratory flow and maximal expiratory pressure seem to be good predictors of grip strength in community-dwelling older adults, but this relationship does not seem to be maintained in institutionalized patients, possibly because of a greater loss of respiratory function.

Relationship of Muscle Mass Determined by DEXA with Spirometric Results in Healthy Individuals

INTRODUCTION

Muscle mass maybe a determining factor in the variability of spirometry results in individuals of the same sex and age who have similar anthropometric characteristics. The aim of this study was to determine the association between spirometric results from healthy individuals and their muscle mass assessed by dual energy X-ray absorptiometry (DEXA).

METHODS

A sample of 161 women and 144 men, all healthy non-smokers, was studied. Ages ranged from18 to77years. For each subject, spirometry results and total and regional lean mass values obtained by full body DEXA were recorded. A descriptive analysis of the variables and a regression analysis were performed to study the relationship between spirometric variables and lean body mass, correcting for age and body mass index (BMI).

RESULTS

In both sexes all muscle mass variables correlated positively and significantly with spirometric variables, and to a greater extent in men. After partial adjustment of correlations by age and BMI, the factor which best explains the spirometric variables is the total lean body mass in men, and trunk lean body mass in women.

CONCLUSIONS

In men, muscle mass in the lower extremities is most closely associated with spirometric results. In women, it is the muscle mass of the trunk. In both sexes muscle mass mainly affects FEV₁.

Associations between body composition, physical capabilities and pulmonary function in healthy older adults

BACKGROUND/OBJECTIVES

There are positive associations between pulmonary function (PF) and fat-free mass as well as muscle strength. Contrarily, negative associations were found with indirect measures of visceral adipose tissue (VAT). We aimed to differentiate between associations of body composition and PF by assessing mediating and moderating effects of physical capabilities.

SUBJECTS/METHODS

Cross-sectional data were assessed among 40 healthy, free-living elderly (20 males) aged 65.1-81.2 years (mean±s.d. age: 72.2±4.3 years; body mass index: 25.6±3.7 kg/m²). Total and regional skeletal muscle (SM), and adipose tissue (AT) were measured using whole-body magnetic resonance imaging. Muscle strength by handgrip dynamometry, physical activity (PA) by questionnaire, and physical performance by gait speed and sit-to-stand test (STS). Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁) were assessed by spirometry.

RESULTS

Positive associations between height-standardized FVC (FVCI) as well as FEV₁ (FEVI), and SM (r=0.435-0.520, P<0.05) were found; subcutaneous AT (SAT) and FVCI correlated negatively (r=-0.374; P<0.05). HGS and PA correlated positively with FEVI (r=0.456-0.608, P<0.05), HGS also with FVCI (r=0.595, P<0.05). Stepwise multiple regression using FVCI and FEVI as dependent variables, and total/thoracic SM, VAT, SAT, HGS, PA and physical performance as independent variables showed that (i) only HGS entered the regression for predicting FVCI (R²=0.351; standard error of estimation (SEE)=0.32 l), and (ii) HGS and PA explained 50% of FEVI (SEE=0.23 l). HGS mediated the relationship between SM and PF; the STS moderated the relationship between SM and FVCI.

CONCLUSIONS

In healthy elderly, PF is positively associated with SM; physical capabilities mediate and moderate these relationships.