Influence of low and normal appendicular lean mass on central blood pressure and wave reflection responses to muscle metaboreflex activation in postmenopausal women

Impaired pulse pressure amplification, augmentation index, and arterial stiffness are associated with reduced limb lean mass in overweight and obese postmenopausal women

BACKGROUND

The age-related muscle mass loss has been associated with increased arterial stiffness (brachial-ankle pulse wave velocity, baPWV) and wave reflection (augmentation index, AIx). In healthy individuals, pulse pressure (PP) is lower in the aorta compared to the brachial artery (PP amplification, PPA). Postmenopausal women experience elevated aortic stiffness leading to increased AIx and aortic PP causing reduced PPA, an independent predictor of cardiovascular mortality. It is unknown whether appendicular skeletal muscle index (ASMI), arm (ArmLM) or leg lean mass (LegLM) are negatively associated with PPA. The purpose of this study was to investigate the associations between vascular function (PPA, AIx, and baPWV) and lean mass (ASMI, ArmLM, and LegLM) in postmenopausal women.

METHODS

The study was performed in 93 postmenopausal women (48-71 years; BMI: 30 ± 7 kg/m²). PPA (brachial/aortic PP), aortic AIx, and baPWV were measured. ArmLM and LegLM were measured by dual-energy X-ray absorptiometry. ASMI was calculated as (ArmLM+LegLM)/Ht². Associations between vascular and lean mass measures were analyzed by multiple linear regression.

RESULTS

PPA was associated with ASMI (β = 0.29, p = .016) and LegLM (β = 0.25, p = .028) after adjustment for age, height, systolic pressure, strength, and heart rate. AIx was associated with ASMI (β = -0.27, p = .011), ArmLM (β = -0.25, p = .023), and LegLM (β = -0.22, p = .026), while baPWV was associated with reduced ASMI (β = -0.23, p = .043) and ArmLM (β = -0.23, p = .045), but not with LegLM (β = -0.19, p = .074) after full adjustment.

CONCLUSIONS

Our findings indicate that impaired pulsatile hemodynamics (PPA and AIx) are negatively associated with ASMI and LegLM, while arterial stiffness is negatively associated with ASMI and ArmLM. Thus, vascular dysfunction may be implicated in muscle mass loss in overweight and obese postmenopausal women.

Unraveling the Links Underlying Arterial Stiffness, Bone Demineralization, and Muscle Loss

The effects of elevated arterial stiffness on cardiovascular outcomes are widely studied, whereas the relation to noncardiovascular outcomes relevant to older persons, such as the effect on bones and muscles, is less well established. Arterial stiffness, bone demineralization, and muscle loss are all age-related processes with common risk factors, however, whether these are just parallel age-related alterations or whether these processes share common pathways is not yet understood. In this review, we outline previous literature using different assessments of arterial stiffness in various populations across the world to produce a comprehensive overview. Although there are many studies showing an association between arterial stiffness and loss of bone and muscle, the majority are cross-sectional and there is limited longitudinal evidence to justify causal conclusions. We also give an in-depth review of hypotheses and possible mechanisms which may underlie these associations including hormone dysregulation, impaired glucose metabolism, and inflammation. This narrative review highlights the associations between vessels, bones, and muscles with aging, offering insights into possible shared pathways.

Attenuated aortic blood pressure responses to metaboreflex activation in older adults with dynapenia

BACKGROUND

Low muscle strength (dynapenia) is a primary characteristic of sarcopenia, the age-related loss of muscle mass and strength or low walking speed. New evidence suggests that muscle strength positively affects blood pressure (BP) responses to exercise. As older adults with lowest handgrip strength also have lowest BP at rest, those with dynapenia may experience attenuated BP responses during physical activity. The purpose of this study was to test the hypothesis that dynapenic older adults would exhibit lower BP response to post-exercise muscle ischemia (PEMI).

METHODS

Brachial and aortic systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) were measured in older adults (age, 80 ± 5 y) with dynapenia (n = 16) and non-dynapenia (n = 9) at rest and during PEMI following 2 min of isometric handgrip exercise at 30% maximal voluntary contraction. Walking speed was assessed by an 8-foot (2.44 m) walk course.

RESULTS

Increases in aortic SBP (11 ± 2 vs. 23 ± 6 mm Hg, p = .03), DBP (6 ± 2 vs.14 ± 4 mm Hg, p = .04), and MAP (8 ± 1 vs. 17 ± 5 mm Hg, p = .02) were lower in dynapenic compared to non-dynapenic adults. Aortic MAP (r = 0.52, p < .05) response to PEMI was correlated with MVC in dynapenic adults. Gait speed was correlated with aortic DBP response to PEMI (r = 0.698, p = .05) in non-dynapenic adults.

CONCLUSIONS

Our findings indicate that aortic DBP response to muscle metaboreflex activation is attenuated in older adults with dynapenia. Normal aortic DBP response during metaboreflex activation may positively affect walking performance in non-dynapenic older adults.

Metaborreflexo inspiratório eleva a pressão arterial em indivíduos obesos e eutróficos

Resumo Introdução: O metaborreflexo, ativado pelo acúmulo de metabólitos durante o exercício, ocasiona vasoconstrição periférica, resultando em elevação da pressão arterial. Indivíduos obesos apresentam redução da endurance muscular inspiratória, sugerindo um acúmulo precoce de metabólitos e, consequentemente, alterações no metaborreflexo inspiratório. Objetivo: Comparar as respostas hemodinâmicas mediadas pelo metaborreflexo inspiratório em indivíduos obesos e em eutróficos. Método: Participaram do estudo vinte indivíduos obesos (31 ± 6 anos, dez homens, 37,5 ± 4,7 kg/m 2 ) e vinte eutróficos (29 ± 8 anos, dez homens, 23,2 ± 1,5 kg/m 2 ) submetidos a avaliação da força muscular respiratória através de manovacuometria. O metaborreflexo inspiratório foi induzido através de exercício resistido a 60% da pressão inspiratória máxima mantido até a exaustão. O protocolo controle consistiu na respiração sem resistência inspiratória (zero cmH 2 O) mantida durante 30 minutos. A pressão arterial e a frequência cardíaca foram mensuradas ao longo dos protocolos, realizados em dias distintos e em ordem randomizada. Resultados: O protocolo de indução do metaborreflexo inspiratório induziu aumento das pressões arteriais sistólica, diastólica e média, bem como da frequência cardíaca semelhante em indivíduos obesos e eutróficos. Conforme esperado, no protocolo controle as variáveis hemodinâmicas permaneceram inalteradas. Conclusão: A força muscular inspiratória não variou (p = 0,814) entre indivíduos obesos e eutróficos. Este estudo sugere que indivíduos obesos apresentam respostas hemodinâmicas, induzidas pelo metaborreflexo inspiratório, semelhantes aos indivíduos eutróficos.