John D. Sorkin

John D. Sorkin

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John D. Sorkin


Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

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

Representative Publications

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1 November 2021 in Journal of Surgical Research
Verified
Journal Article
Closed access
NPNikhil K. Prasad
Nikhil K. Prasad
BEBrian R. Englum
Brian R. Englum
DTDouglas J. Turner
Douglas J. Turner
RLRachel Lake
Rachel Lake
TSTariq Siddiqui
Tariq Siddiqui
BLBrajesh K. Lal
Brajesh K. Lal

30 July 2013 in Neurorehabilitation and Neural Repair
Verified
Journal Article
Open access
PDF file
ASAlyssa D. Stookey
Alyssa D. Stookey
MMMichael G. McCusker
Michael G. McCusker
JSJohn D. Sorkin
John D. Sorkin
LKLeslie I. Katzel
Leslie I. Katzel
MSMarianne Shaughnessy
Marianne Shaughnessy
FIFrederick M. Ivey
Frederick M. Ivey
Purpose. Impaired economy of gait, prevalent in chronic stroke secondary to residual gait deficits, is associated with intolerance for performing activities of daily living. Gait economy/efficiency is traditionally assessed by determining the rate of oxygen consumption during submaximal treadmill walking. However, the mechanics and energetics of treadmill versus overground walking are very different in stroke survivors with ambulatory deficits. Clearly, overground cardiopulmonary measures are needed to accurately profile movement economy after stroke. An obstacle to obtaining such measures after stroke has been the absence of reliable portable metabolic monitoring equipment. The purpose of this study was to establish the test–retest reliability of a portable metabolic monitoring device during overground walking in hemiparetic stroke survivors. Methods. Twenty-three chronic hemiparetic stroke survivors underwent two 6-minute walk tests while wearing a COSMED K4b2 portable metabolic measurement system. Intraclass correlations coefficients (ICC) were calculated for both cardiopulmonary parameters and distance covered to determine test–retest reliability. An ICC of ≥0.85 was considered reliable. Results. ICCs for relative Vo2 (0.90), absolute Vo2 (0.93), Vco2 (0.93), and minute ventilation (0.95) demonstrated high reliability, but not for heart rate (0.76) or respiratory exchange ratio (0.64). There was no significant difference in the distance each participant walked between the first and second tests, eliminating distance as a potential confounder of our analyses (ICC = 0.99). Conclusions. Our results strongly support the reliability of the K4b2 for quantifying overground gait efficiency after stroke. Use of this device may enable researchers to study how varying poststroke rehabilitation interventions affect this central measure of health and function.

26 May 2025 in Nutrients
Verified
Journal Article
Open access
PDF file
GBGalya Bigman
Galya Bigman
Marius Emil RusuMarius Emil Rusu
Marius Emil Rusu
NSNicole Shelawala
Nicole Shelawala
JSJohn D. Sorkin
John D. Sorkin
BBBrock A. Beamer
Brock A. Beamer
Alice RyanAlice Ryan
Alice Ryan
Background/Objectives: Long COVID-19 is characterized by persistent symptoms lasting three months or more following SARS-CoV-2 infection. Nutrition has emerged as a modifiable factor influencing recovery trajectories and symptom burden; however, existing evidence remains fragmented across diverse study designs and populations. This scoping review synthesized global evidence on the role of diet and nutrition in managing long COVID-19 symptoms and supporting recovery. Methods: Following PRISMA-ScR and Joanna Briggs Institute guidelines for scoping reviews, we searched major biomedical databases for studies published between 2020 and 2025. Eligible studies examined dietary intake, nutritional status, or nutrition-related interventions in adults with long COVID-19. Results: After duplicates were removed, 1808 records were screened, resulting in 50 studies that met the inclusion criteria—27 intervention studies and 23 observational studies. Nutritional exposures included micronutrients (e.g., vitamins D, K2), amino acids (e.g., L-arginine), multinutrient formulations, microbiota-targeted therapies (e.g., probiotics, synbiotics), nutritional status, diet quality, and whole-diet patterns (e.g., the Mediterranean diet). Approximately 76% of studies reported improvements in long COVID-19-related symptoms such as fatigue, mood disturbances, physical function, and markers of inflammation. Conclusions: Diet and nutrition may support long COVID-19 recovery by targeting inflammation and the gut microbiome to alleviate symptoms and improve functional outcomes. Well-powered trials of whole-diet approaches, combined with targeted supplementation, are needed to confirm their potential as scalable, accessible tools for post-COVID-19 recovery and management.

13 July 2021 in The American Journal of Clinical Nutrition
Verified
Journal Article
Open access
PDF file
JSJohn D Sorkin
John D Sorkin
MMMark Manary
Mark Manary
PSPaul A M Smeets
Paul A M Smeets
AMAmanda J MacFarlane
Amanda J MacFarlane
AAArne Astrup
Arne Astrup
DTDeirdre K Tobias
Deirdre K Tobias
Two questions regarding the scientific literature have become grist for public discussion: 1) what place should P values have in reporting the results of studies? 2) How should the perceived difficulty in replicating the results reported in published studies be addressed? We consider these questions to be 2 sides of the same coin; failing to address them can lead to an incomplete or incorrect message being sent to the reader. If P values (which are derived from the estimate of the effect size and a measure of the precision of the estimate of the effect) are used improperly, for example reporting only significant findings, or reporting P values without account for multiple comparisons, or failing to indicate the number of tests performed, the scientific record can be biased. Moreover, if there is a lack of transparency in the conduct of a study and reporting of study results, it will not be possible to repeat a study in a manner that allows inferences from the original study to be reproduced or to design and conduct a different experiment whose aim is to confirm the original study's findings. The goal of this article is to discuss how P values can be used in a manner that is consistent with the scientific method, and to increase transparency and reproducibility in the conduct and analysis of nutrition research.

9 December 2024 in Nutrients
Verified
Journal Article
Open access
PDF file
GBGalya Bigman
Galya Bigman
Marius Emil RusuMarius Emil Rusu
Marius Emil Rusu
AKAmber S. Kleckner
Amber S. Kleckner
JSJohn D. Sorkin
John D. Sorkin
YJYichen Jin
Yichen Jin
Alice RyanAlice Ryan
Alice Ryan
Background: Plant-based diets are associated with various health benefits; however, their impact on physical performance in aging populations remains unclear. Objectives: To investigate the associations between adherence to plant-based diets and physical performance, focusing on their potential protective effects against age-related declines in function. Methods: Data were obtained from men and women aged 40 years or older in the Baltimore Longitudinal Study of Aging (BLSA) (mean ± SD age: 68 ± 13 years at the first dietary visit; n = 1389). Dietary intake was assessed using a food frequency questionnaire (FFQ). Plant-based diets, calculated from 18 food groups, were categorized as overall (PDI), healthful (hPDI), or unhealthful (uPDI), and their tertiles across visits were analyzed. Multivariable linear mixed-effects models were used to examine the association between repeated measurements of three physical performance outcomes—Short Physical Performance Battery (SPPB), grip strength (kg), and gait speed (m/s)—and adherence to each plant-based diet. Results: In fully adjusted models, SPPB and grip strength were significantly associated with both hPDI and uPDI, but not with PDI. For hPDI, the intermediate tertile showed the greatest benefit, with SPPB scores 0.5 points higher (βT2vs.T1 = 0.50, 95% CI: 0.30–0.70, p < 0.001) over the follow-up period. In contrast, for uPDI, a 0.27-point lower SPPB score was seen (βT3vs.T1 = −0.27, 95% CI: −0.48 to −0.07, p = 0.009). Longitudinally, grip strength was positively associated with hPDI (βT3vs.T1 = 1.14, 95% CI: 0.24–2.05, p = 0.0013). Similar results were observed in older adults aged ≥65 years. Conclusions: Adherence to hPDI may benefit lower body function and muscle strength, while uPDI appears to have adverse effects. This suggests that the quality of plant-based foods is essential for maintaining functional well-being in older adults. Further research is needed to confirm these findings, explore underlying mechanisms, and identify strategies to optimize plant-based dietary patterns for aging populations.

20 August 2020 in Brain Sciences
Verified
Journal Article
Open access
PDF file
Ruth AkinlosotuRuth Akinlosotu
Ruth Akinlosotu
NANesreen Alissa
Nesreen Alissa
JSJohn D. Sorkin
John D. Sorkin
GWGeorge F. Wittenberg
George F. Wittenberg
KWKelly Westlake
Kelly Westlake
The objective of this study was to examine age-related differences in arm and trunk responses during first and repeated step induced balance perturbations. Young and older adults received 10 trials of unpredictable lateral platform translations. Outcomes included maximum arm and trunk displacement within 1 s of perturbation and at first foot lift off (FFLO), arm and neck muscle activity as recorded using electromyography (EMG), initial step type, balance confidence, and percentage of harness-assisted trials. Compared to young adults, older adults demonstrated greater arm and trunk angular displacements during the first trial, which were present at FFLO and negatively associated with balance confidence. Unlike young adults, recovery steps in older adults were directed towards the fall with a narrowed base of support. Over repeated trials, rapid habituation of first-trial responses of bilateral arm and trunk displacement and EMG amplitude was demonstrated in young adults, but was absent or limited in older adults. Older adults also relied more on harness assistance during balance recovery. Exaggerated arm and trunk responses to sudden lateral balance perturbations in older adults appear to influence step type and balance recovery. Associations of these persistently amplified movements with an increased reliance on harness assistance suggest that training to reduce these deficits could have positive effects in older adults with and without neurological disorders.