Relationship between dynapenia and cardiorespiratory functions in healthy postmenopausal women: novel clinical criteria

Objective: Muscle strength seems to be a better indicator of physical limitations than skeletal muscle mass is. The purpose of this study was to investigate, using a new developed clinical tool, the relationship between type I dynapenia and cardiorespiratory functions in postmenopausal women. Methods: Forty-six postmenopausal women were recruited and divided into two groups (dynapenic vs nondynapenic). Body composition (bioelectrical impedancemetry), muscle strength (dynamometer), cardiorespiratory functions (maximum oxygen consumption and forced expiratory volume in 1 second), resting energy expenditure (indirect calorimetry), and dietary intake (3-d dietary journal) were measured. Results: Type I dynapenia was defined as less than 1.53 kg per skeletal muscle mass (kg) based on handgrip dynamometer. Significant differences were found between dynapenic (n = 23) and nondynapenic (n = 23) postmenopausal women for cardiorespiratory functions (maximum oxygen consumption, P = 0.003; and forced expiratory volume in 1 second, P = 0.046). We observed no differences between groups for age, age at menopause, use of hormone therapy, body mass index, waist circumference, fat mass, resting energy expenditure, and total energy intake, which are known to be potential confounders. No differences were observed for cardiorespiratory functions when our population was divided into sarcopenic and nonsarcopenic groups. Conclusions: Type I dynapenic women have significantly poorer cardiorespiratory functions that do nondynapenic women even if they presented the same skeletal muscle mass index. Thus, based on our results, dynapenia could potentially be used as a marker of cardiorespiratory functions. The clinical method developed to identify dynapenic women could be used by health professionals.