Sandra Silva Martins

Prof. Sandra Silva Martins


Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 November 2024 in Nutrients
Verified
Journal Article
Open access
PDF file
Cláudia MendesCláudia Mendes
Cláudia Mendes
MCManuel Carvalho
Manuel Carvalho
JBJorge Bravo
Jorge Bravo
SMSandra Silva Martins
Sandra Silva Martins
Armando RaimundoArmando Raimundo
Armando Raimundo
Introduction: Leptin and ghrelin are two hormones that play a role in weight homeostasis. Leptin, which is produced primarily by adipocytes and is dependent on body fat mass, suppresses appetite and increases energy expenditure. Conversely, ghrelin is the “hunger hormone”, it stimulates appetite and promotes fat storage. Bariatric surgery significantly alters the levels and activity of these hormones, contributing to weight loss and metabolic improvements. Clarifying the interplay between bariatric surgery, weight loss, physical exercise, leptin, and ghrelin is essential in developing comprehensive strategies for optimizing the long-term outcomes for candidates who have undergone bariatric surgery, especially for sarcopenic patients. Methods: This was a randomized controlled study with two groups (n = 22). The patients in both groups had obesity and sarcopenia. A Roux-en-Y-gastric bypass (RYGB) procedure was performed on all patients. The intervention group participated in a structured exercise program three times per week, beginning one month after surgery and lasting 16 weeks. Patient assessment was performed before surgery (baseline) and after the completion of the exercise program. The control group received the usual standard of care and was assessed similarly. Results: After surgery, weight, BMI, and lean mass decreased significantly in both groups between the baseline and the second assessment. Leptin levels were not significantly different between baseline and the second assessment in the physical exercise group, but were significantly lower in the control group (p = 0.05). Ghrelin levels increased over time in both groups, but the differences were not significant. When we associated leptin (the dependent variable) with weight (the independent variable), we found that lower weight was associated with lower leptin levels. A similar relationship was also observed between the leptin and sarcopenia parameters (muscle strength and mass), as well as in the bone health parameters (bone mineral density and t-score). Higher ghrelin levels were significantly associated with higher t-scores and z-scores (p < 0.05). Conclusion: Exercise has been shown to have a significant effect on leptin and ghrelin levels after bariatric surgery. By incorporating regular physical activity into their lifestyle, bariatric patients can optimize their weight loss outcomes and improve their overall health. After the physical exercise protocol, patients in the intervention group revealed more established leptin levels, which may indicate a protected pattern concerning decreased leptin levels. An unfavorable profile was evidenced, according to which greater weight loss, sarcopenia, and osteoporosis were associated with lower leptin levels.

24 September 2024 in Preprints.org
Verified
Preprint
Open access
PDF file
Cláudia MendesCláudia Mendes
Cláudia Mendes
MCManuel Carvalho
Manuel Carvalho
JBJorge Bravo
Jorge Bravo
SMSandra Silva Martins
Sandra Silva Martins
Armando RaimundoArmando Raimundo
Armando Raimundo
Introduction: Leptin and ghrelin are two hormones that play a role in weight homeostasis. Leptin, which is produced primarily by adipocytes and is dependent on body fat mass, suppresses appetite and increases energy expenditure. Conversely, ghrelin is the “hunger hormone”, it stimulates appetite and promotes fat storage. Bariatric surgery significantly alters the levels and activity of these hormones, contributing to weight loss and metabolic improvements. Clarifying the interplay between bariatric surgery, weight loss, physical exercise, leptin, and ghrelin is essential for developing comprehensive strategies for optimizing long-term outcomes for candidates for bariatric surgery, especially sarcopenic patients. Methods: This was a randomized controlled study with two groups (n=22). The patients in both groups have obesity and sarcopenia. A Roux-en-Ygastric bypass (RYGB) procedure was performed in all patients. The intervention group participated in a structured exercise program three times per week beginning one month after surgery and lasting 16 weeks. Patient assessment was performed before surgery (baseline) and after completion of the exercise program. The control group received the usual standard of care and was assessed similarly. Results: After surgery, weight, BMI and lean mass decreased significantly in both groups from baseline to the second assessment. Leptin was not significantly different from baseline to the second assessment in the physical exercise group but was significantly lower in the control group (p=0.05). Ghrelin increased over time in both groups, but the differences were not significant. When we associated leptin (the dependent variable) with weight (the independent variable), we found that lower weight was associated with lower leptin levels. A similar relationship was also observed between leptin and sarcopenia parameters (muscle strength and mass), as well as with bone health parameters (bone mineral density and t-score). Higher ghrelin levels were significantly associated with higher t-scores and z-score (p<0.05). Conclusion: Exercise has been shown to have a significant effect on leptin and ghrelin levels after bariatric surgery. By incorporating regular physical activity into their lifestyle, bariatric patients can optimize their weight loss outcomes and improve their overall health. After the physical exercise protocol, patients in the intervention group revealed more established leptin levels, which may indicate a protected pattern concerning decreased leptin levels. An unfavorable profile was evidenced, according to which greater weight loss, sarcopenia, and osteoporosis were associated with lower leptin levels.

12 July 2024 in Preprints.org
Verified
Preprint
Open access
PDF file
Cláudia MendesCláudia Mendes
Cláudia Mendes
MCManuel Carvalho
Manuel Carvalho
JBJorge Bravo
Jorge Bravo
SMSandra Silva Martins
Sandra Silva Martins
Armando RaimundoArmando Raimundo
Armando Raimundo
Introduction: Obesity affects over 650 million individuals worldwide and it is a major public health problem. Bariatric surgery is the most effective treatment for severe obesity, resulting in significant weight reduction and improvement in obesity-related conditions. However, the weight loss achieved through bariatric surgery often correlates with a notable decrease in skeletal muscle. This correlation suggests an elevated risk of sarcopenia among patients after surgery. The aim of this study was to evaluate the effects of obesity and bariatric surgery on sarcopenia-related indicators and diagnosis before and after surgery. Methods: A total of 17 bariatric surgery patients were included in this prospective study. The parameters to diagnose sarcopenia were determined for each participant, based on EWGSOP2 and EASO/ESPEN consensuses. All evaluations were performed on the five moments of this study: before surgery and at 1, 6, 12 and 18 months after surgery. Results: In this study, 88.2% of the subjects were female, the mean BMI was 42.9 kg/m² and the mean weight was 105.9 kg. After surgery, the mean weight consistently decreased, with all differences from baseline being statistically significant (p<0.001). When using the SARC-F questionnaire for screening, the risk of sarcopenia increased post-surgery, and decreased at 12 months, declining to zero at 18 months. Muscle strength decreased significantly (p=0.002) at the 1 month after surgery assessment, with slight variations thereafter, none statistically significant. Muscle mass was normal before surgery but decreased significantly post-surgery (p<0.001). When applying the ESPEN/EASO consensus cut-off criteria for sarcopenic obesity, 35.3% of the patients met the criteria preoperatively. After surgery, the results increased to 70.6% in the first month but decreased afterward to 41.2% at 6 months. Discussion: This study evaluated the impact of bariatric surgery on sarcopenia and sarcopenic obesity, for a duration of up to 18 months after surgery, using the EWGSOP2 and ESPEN/EASO consensuses criteria. Bariatric surgery, the most effective treatment for severe obesity, often results in muscle mass loss alongside fat loss. Handgrip strength, a key sarcopenia indicator, showed a significant early post-surgery decline, whereas the weight-dependent sit-to-stand test did not. This suggests weight loss impacts different muscle function tests variably. Muscle mass decreased continuously after surgery. However, other indicators had mixed results. Applying ESPEN/EASO guidelines, the study found a temporary post-surgery increase in sarcopenic obesity, peaking at one month and returning to pre-surgery levels by six months. However, different criteria led to different results. Conclusion: The results indicate a clear deleterious impact of bariatric surgery on muscle strength and mass, the most important indicators of sarcopenia. Also, the impact seems to occur very early after surgery, indicating that the appropriate timeframe to try to prevent this effect may be the prehabilitation period followed by the post-surgery timeframe.

30 August 2024 in Preprints.org
Verified
Preprint
Open access
PDF file
CMCláudia Mendes
Cláudia Mendes
MCManuel Carvalho
Manuel Carvalho
JBJorge Bravo
Jorge Bravo
SMSandra Silva Martins
Sandra Silva Martins
Maria Otília ZangãoMaria Otília Zangão
Maria Otília Zangão
Armando RaimundoArmando Raimundo
Armando Raimundo
(1) Background: Sarcopenia, a condition characterized by a decrease in muscle mass and strength, is very common in patients with obesity and can be aggravated by bariatric surgery, potentially compromising the clinical results of surgery. There is increasing interest in pa-tient-reported outcome measures (PROMs) to assess results in other health variables that may be especially important for individual patients. The role of exercise in enhancing health-related quality of life (HRQoL) after surgery remains underexplored. This study investigated the impact of exercise on HRQoL in bariatric sarcopenic patients via the Sarcopenia Quality of Life (SarQoL) questionnaire. (2) Method: Candidates for surgery took part in the EXPOBAR program and were randomized into experimental and control groups. The intervention lasted 16 weeks, starting one month after surgery, and included combined aerobic and resistance exercise. Outcomes, including body composition and physical fitness parameters, were measured before and after the intervention. All participants underwent gastric bypass surgery (RYGB). (3) Results: The baseline characteristics of the participants were not significantly different between the two groups. All patients met the criteria for moderate/severe obesity and the EASO/ESPEN criteria for sarcopenia, namely, reduced muscle strength assessed by grip strength and reduced muscle mass assessed by the ASMM score/weight. After completing the study protocol, patients in both groups had increased HRQoL, but the increase was significantly greater in the intervention group than in the control group. (4) Conclusion: Our findings suggest that exercise plays a crucial role in improving both physical and psychological well-being in postbariatric patients, highlighting the need to integrate structured exercise programs in post-surgery care. This study was prospectively registered at Clinicaltrials.gov (NCT03497546).