Salvador J. Jaime

Influence of L-citrulline and watermelon supplementation on vascular function and exercise performance.

Purpose of review L-Citrulline, either synthetic or in watermelon, may improve vascular function through increased L-arginine bioavailability and nitric oxide synthesis. This article analyses potential vascular benefits of L-citrulline and watermelon supplementation at rest and during exercise. Recent findings There is clear evidence that acute L-citrulline ingestion increases plasma L-arginine, the substrate for endothelial nitric oxide synthesis. However, the subsequent acute improvement in nitric oxide production and mediated vasodilation is inconsistent, which likely explains the inability of acute L-citrulline or watermelon to improve exercise tolerance. Recent studies have shown that chronic L-citrulline supplementation increases nitric oxide synthesis, decreases blood pressure, and may increase peripheral blood flow. These changes are paralleled by improvements in skeletal muscle oxygenation and performance during endurance exercise. The antihypertensive effect of L-citrulline/watermelon supplementation is evident in adults with prehypertension or hypertension, but not in normotensives. However, L-citrulline supplementation may attenuate the blood pressure response to exercise in normotensive men. Summary The beneficial vascular effects of L-citrulline/watermelon supplementation may stem from improvements in the L-arginine/nitric oxide pathway. Reductions in resting blood pressure with L-citrulline/watermelon supplementation may have major implications for individuals with prehypertension and hypertension. L-Citrulline supplementation, but not acute ingestion, have shown to improve exercise performance in young healthy adults.

Combined whole-body vibration training and l-citrulline supplementation improves pressure wave reflection in obese postmenopausal women.

Postmenopausal women have increased wave reflection (augmentation pressure (AP) and index (AIx)) and reduced muscle function that predispose them to cardiac diseases and disability. Our aim was to examine the combined and independent effects of whole-body vibration training (WBVT) and l-citrulline supplementation on aortic hemodynamics and plasma nitric oxide metabolites (NOx) in postmenopausal women. Forty-one obese postmenopausal women were randomized to 3 groups: l-citrulline, WBVT+l-citrulline and WBVT+Placebo for 8 weeks. Brachial and aortic systolic blood pressure, diastolic blood pressure, AP, AIx, AIx adjusted to 75 beats/min (AIx@75), and NOx were measured before and after 8 weeks. All groups similarly decreased (P < 0.05) brachial and aortic pressures as well as AP, and similarly increased (P < 0.05) NOx levels. AIx and AIx@75 decreased (P < 0.01) in the WBVT+l-citrulline and WBVT+Placebo groups, but not in the l-citrulline group. The improvement in AIx@75 (-10.5% ± 8.8%, P < 0.05) in the WBVT+l-citrulline group was significant compared with the l-citrulline group. l-Citrulline supplementation and WBVT alone and combined decreased blood pressures. The combined intervention reduced AIx@75. This study supports the effectiveness of WBVT+l-citrulline as a potential intervention for prevention of hypertension-related cardiac diseases in obese postmenopausal women.

Benefits of whole-body vibration training on arterial function and muscle strength in young overweight/obese women

The early arterial dysfunction linked with obesity and a sedentary lifestyle heightens the likelihood of suffering from future cardiovascular events. Whole-body vibration training (WBVT) may improve systemic arterial stiffness (brachial-ankle pulse wave velocity (baPWV)) and muscle strength in pre- and post-menopausal women. However, the effectiveness of WBVT to impact the arterial segments included in baPWV is unknown. The aim of this study was to investigate the effects of WBVT on aortic and leg arterial stiffness in young sedentary overweight/obese women. Thirty-eight young (21 years) overweight/obese women were randomized to WBVT (n=25) or a nonexercising control (CON, n=13) groups for 6 weeks. PWV, brachial and aortic blood pressures (BP), wave reflection (augmentation index (AIx)) and leg muscle strength measurements were acquired before and after 6 weeks. WBVT significantly reduced carotid-femoral PWV (aortic stiffness, P<0.05), femoral-ankle (leg arterial stiffness, P<0.01) and baPWV (systemic arterial stiffness, P<0.01) compared with CON. The reduction in brachial systolic BP (SBP), heart rate, aortic SBP, aortic diastolic BP, AIx normalized to a heart rate of 75 beats per min (AIx@75; P<0.01) and AIx (P<0.05) following WBVT was significant compared with CON (P<0.05). WBVT increased leg muscle strength compared with CON (P<0.001). There was a significant negative correlation between changes in relative muscle strength and aortic stiffness (r=−0.41, P<0.05). WBVT led to reductions in arterial stiffness, central BP and wave reflection in young obese women. WBVT may be an effective intervention toward vascular health promotion and prevention in young overweight/obese women (ClinicalTrials.gov identifier: NCT02679898).

l -Citrulline supplementation attenuates blood pressure, wave reflection and arterial stiffness responses to metaboreflex and cold stress in overweight men

Combined isometric exercise or metaboreflex activation (post-exercise muscle ischaemia (PEMI)) and cold pressor test (CPT) increase cardiac afterload, which may lead to adverse cardiovascular events. l-Citrulline supplementation (l-CIT) reduces systemic arterial stiffness (brachial-ankle pulse wave velocity (baPWV)) at rest and aortic haemodynamic responses to CPT. The aim of this study was to determine the effect of l-CIT on aortic haemodynamic and baPWV responses to PEMI+CPT. In all, sixteen healthy, overweight/obese males (age 24 (sem 6) years; BMI 29·3 (sem 4·0) kg/m2) were randomly assigned to placebo or l-CIT (6 g/d) for 14 d in a cross-over design. Brachial and aortic systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP), aortic augmented pressure (AP), augmentation index (AIx), baPWV, reflection timing (Tr) and heart rate (HR) were evaluated at rest and during isometric handgrip exercise (IHG), PEMI and PEMI+CPT at baseline and after 14 d. No significant effects were evident after l-CIT at rest. l-CIT attenuated the increases in aortic SBP and wave reflection (AP and AIx) during IHG, aortic DBP, MAP and AIx during PEMI, and aortic SBP, DBP, MAP, AP, AIx and baPWV during PEMI+CPT compared with placebo. HR and Tr were unaffected by l-CIT in all conditions. Our findings demonstrate that l-CIT attenuates aortic blood pressure and wave reflection responses to exercise-related metabolites. Moreover, l-CIT attenuates the exaggerated arterial stiffness response to combined metaboreflex activation and cold exposure, suggesting a protective effect against increased cardiac afterload during physical stress.

Impact of age on aortic wave reflection responses to metaboreflex activation and its relationship with leg lean mass in post-menopausal women

Wave reflection (augmentation pressure [AP] and index [AIx]) is greater in older women than men. Resting AP is a better wave reflection index than AIx in older adults. The negative relationship between wave reflection and lean mass (LM) has been inconsistent. We investigated the impact of age and LM on aortic hemodynamic responses to metaboreflex activation in post-menopausal women. Post-menopausal women, younger and older (n=20 per group) than 60 years, performed 2-min isometric handgrip at 30% of maximal force followed by 3-min post-exercise muscle ischemia (PEMI). We measured carotid-femoral pulse wave velocity (cfPWV) and femoral-ankle PWV (faPWV) at rest, and aortic systolic blood pressure (aSBP), pulse pressure (aPP), AP, AIx, and AIx-adjusted for heart rate (AIx@75) at rest and during PEMI using tonometry. Arm and leg LM were measured by DEXA. Resting cfPWV, aSBP, and aPP were higher, while AIx@75 and leg LM were lower in older than younger women. aSBP and aPP increased similarly during PEMI in both groups. Increases in AP (P<0.05), AIx (P<0.05), and AIx@75 (P<0.01) during PEMI were greater in older than younger women. From these responses, only AP during PEMI was correlated (P<0.05) positively with aSBP and aPP responses, and negatively with leg LM. Resting faPWV, but not cfPWV, was correlated (P<0.01) with AP, aSBP, and aPP during PEMI. Therefore, PEMI induces greater wave reflection responses in older than younger post-menopausal women. Our findings suggest that the increased AP response to PEMI is related to leg arterial stiffness and muscle loss in older women.

Whole-body vibration as a potential countermeasure for dynapenia and arterial stiffness

Age-related decreases in muscle mass and strength are associated with decreased mobility, quality of life, and increased cardiovascular risk. Coupled with the prevalence of obesity, the risk of death becomes substantially greater. Resistance training (RT) has a well-documented beneficial impact on muscle mass and strength in young and older adults, although the high-intensity needed to elicit these adaptations may have a detrimental or negligible impact on vascular function, specifically on arterial stiffness. Increased arterial stiffness is associated with systolic hypertension, left ventricular hypertrophy, and myocardial ischemia. Therefore, improvements of muscle strength and arterial function are important in older adults. Recently, whole-body vibration (WBV) exercise, a novel modality of strength training, has shown to exhibit similar results on muscle strength as RT in a wide-variety of populations, with the greatest impact in elderly individuals with limited muscle function. Additionally, WBV training has been shown to have beneficial effects on vascular function by reducing arterial stiffness. This article reviews relevant publications reporting the effects of WBV on muscle strength and/or arterial stiffness. Findings from current studies suggest the use of WBV training as an alternative modality to traditional RT to countermeasure the age-related detriments in muscle strength and arterial stiffness in older adults.

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

Sarcopenia, defined by reduced appendicular skeletal muscle mass (ASM)/height2 (ASMI), is associated with increased arterial stiffness (brachial‐ankle pulse wave velocity, baPWV) and wave reflection (augmentation index, AIx). Blood pressure (BP) responses to metaboreflex activation (post‐exercise muscle ischemia, PEMI) are exaggerated in older prehypertensives and hypertensives. We examined peripheral and aortic haemodynamics at rest and during PEMI in postmenopausal women with low‐ASMI and normal‐ASMI. Resting radial AIx and baPWV as well as brachial and aortic systolic BP, pulse pressure, systolic time index, and subendocardial viability ratio (SEVR) responses to PEMI were greater in women with low‐ASMI than normal‐ASMI. Increased baPWV associated with low‐ASMI may play a major role in the exaggerated pulse pressure and SEVR responses to PEMI in postmenopausal women.