Aging brings damage to the musculoskeletal system, which may result in a decline in neuromuscular strength, a condition called dynapenia. Additionally, there may be impairment of strength and/or respiratory function, which promotes negative outcomes and can potentiate or accelerate the onset of dynapenia in older adults. Previous studies have shown the association of respiratory variables with sarcopenia, as well as suggesting cut-off points as diagnostic criteria for this condition. However, the identification of the association between peak expiratory flow (PEF) obtained by means of the peak flow meter with dynapenia, as well as the proposition of cut-off points to predict it in brazilian older adults, have not yet been found in the available literature.

To compare the values of PEF between dynapenic and non-dynapenic older adults, to assess the association of PEF with the diagnosis of dynapenia, and to establish cutoff points for PEF to predict dynapenia.

Cross-sectional study conducted with 382 (70,03±7,30 years) community-dwelling older adults from the urban area of Macapá, Amapá. Peak expiratory flow (PEF) obtained using a Peak Flow Meter and dynapenia based on handgrip strength were evaluated, considering three diagnostic criteria: 1(<26 kg for men and <16 kg for women), 2(<30 kg for men and <20 kg for women), and 3(based on the sample's BMI and sex). The Student's t-test was used for group comparisons, and crude and adjusted analyses using a binary logistic regression model were performed to verify the association between PEF and dynapenia (p<0,05). Receiver Operating Characteristic (ROC) curves with parameters of area under the ROC curve (AUC), sensitivity, and specificity, with a 95% confidence interval and a significance level of 5%, were generated to identify potential PEF cut-off points as discriminators of dynapenia.

Lower PEF values were observed in those with dynapenia when compared to those with non-dynapenia (p<0,001); and in the adjusted analysis, there was an inverse association between PEF and dynapenia, independent of the cutoff point considered (p<0,05). Cutoff points were established for PEF as a discriminator of dynapenia, namely: 1 (PEF≤260L/min; AUC=0.631; sensitivity=70.42%; specificity=49.20%), 2 (PEF≤280L/min; AUC=0.624; sensitivity=71.94%; specificity=45.27%) and 3 (PEF≤250L/min; AUC=0.640; sensitivity=70.37%; specificity=52.82%).

The elderly with dynapenia had lower PEF values compared to the elderly without dynapenia. In addition, PEF cut-off points have been proposed to predict dynapenia, results which demonstrate that PEF seems to influence the dynapenia process.

The identification of the association and the diagnostic criteria for dynapenia based on PEF, using the peak flow meter, a portable device widely used by physical therapists, can help to screen for this condition and based on this, propose measures for prevention and care of the elderly respiratory health.