Caffeinated Gum Does Not Influence RPE-Regulated Cadence in Recreationally-Active, College Females Regardless of Habitual Caffeine Consumption

International Journal of Exercise Science 14(2): 1375-1387, 2021. Caffeine (CAF) has been extensively studied for its ergogenic and analgesic effects during exercise. However, the majority of these studies have been conducted in male populations. This study investigated the effects of acute CAF chewing gum on self-selected exercise intensity during a rating of perceived exertion (RPE) production trial in active females (n = 16, 21.0 ± 2.8 y). Data were also analyzed based on habitual CAF consumption level. Participants completed a V̇O2peak trial, followed by a familiarization and two randomized, triple-blinded experimental RPE production trials on an arm ergometer [clamped resistance, blinded to self-selected cadence (CAD)] with either CAF gum (300 mg; 4.8 ± 0.7 mg/kg-1 body mass) or placebo (PLA), at a prescribed RPE of 4 and 7 (10 min each). Self-selected CAD did not statistically differ (p \u3e 0.05) between CAF or PLA for an RPE4 (37.7 ± 1.6 vs. 37.6 ± 1.6 rev·min-1) or RPE7 (42.9 ± 1.6 vs. 41.2 ± 1.7 rev·min-1), respectively. There were no statistical differences between treatment groups for any other variables, except restlessness rating which was significantly higher (3.5 vs. 2.2; p = 0.03, d = 0.64) for the CAF group compared to PLA. Secondary analysis revealed no statistical differences for any variables between habitual consumers of low (23 ± 20 mg/day) or mod/high (195 ± 93 mg/day) CAF. Our data support previous studies examining CAF in women across different testing modalities and suggest that regardless of habitual CAF consumption, females might require higher doses of CAF to replicate subjective and physiological responses commonly observed using similar RPE production protocols in male participants. These findings support the need for additional investigations into female physiological and perceptual responses following CAF ingestion

Ceacam1 separates graft-versus-host-disease from graft-versus-tumor activity after experimental allogeneic bone marrow transplantation.

BACKGROUND: Allogeneic bone marrow transplantation (allo-BMT) is a potentially curative therapy for a variety of hematologic diseases, but benefits, including graft-versus-tumor (GVT) activity are limited by graft-versus-host-disease (GVHD). Carcinoembryonic antigen related cell adhesion molecule 1 (Ceacam1) is a transmembrane glycoprotein found on epithelium, T cells, and many tumors. It regulates a variety of physiologic and pathological processes such as tumor biology, leukocyte activation, and energy homeostasis. Previous studies suggest that Ceacam1 negatively regulates inflammation in inflammatory bowel disease models. METHODS: We studied Ceacam1 as a regulator of GVHD and GVT after allogeneic bone marrow transplantation (allo-BMT) in mouse models. In vivo, Ceacam1(-/-) T cells caused increased GVHD mortality and GVHD of the colon, and greater numbers of donor T cells were positive for activation markers (CD25(hi), CD62L(lo)). Additionally, Ceacam1(-/-) CD8 T cells had greater expression of the gut-trafficking integrin α(4)β(7), though both CD4 and CD8 T cells were found increased numbers in the gut post-transplant. Ceacam1(-/-) recipients also experienced increased GVHD mortality and GVHD of the colon, and alloreactive T cells displayed increased activation. Additionally, Ceacam1(-/-) mice had increased mortality and decreased numbers of regenerating small intestinal crypts upon radiation exposure. Conversely, Ceacam1-overexpressing T cells caused attenuated target-organ and systemic GVHD, which correlated with decreased donor T cell numbers in target tissues, and mortality. Finally, graft-versus-tumor survival in a Ceacam1(+) lymphoma model was improved in animals receiving Ceacam1(-/-) vs. control T cells. CONCLUSIONS: We conclude that Ceacam1 regulates T cell activation, GVHD target organ damage, and numbers of donor T cells in lymphoid organs and GVHD target tissues. In recipients of allo-BMT, Ceacam1 may also regulate tissue radiosensitivity. Because of its expression on both the donor graft and host tissues, this suggests that targeting Ceacam1 may represent a potent strategy for the regulation of GVHD and GVT after allogeneic transplantation

Tension-Compression Loading with Chemical Stimulation Results in Additive Increases to Functional Properties of Anatomic Meniscal Constructs

Objective: This study aimed to improve the functional properties of anatomically-shaped meniscus constructs through simultaneous tension and compression mechanical stimulation in conjunction with chemical stimulation. Methods: Scaffoldless meniscal constructs were subjected to simultaneous tension and compressive stimulation and chemical stimulation. The temporal aspect of mechanical loadingwas studied by employing two separate five day stimulation periods. Chemical stimulation consisted of the application of a catabolic GAG-depleting enzyme, chondroitinase ABC (C-ABC), and an anabolic growth factor, TGF-b1. Mechanical and chemical stimulation combinations were studied through a full-factorial experimental design and assessed for histological, biochemical, and biomechanical properties following 4 wks of culture. Results: Mechanical loading applied from days 10–14 resulted in significant increases in compressive, tensile, and biochemical properties of meniscal constructs. When mechanical and chemical stimuliwere combined significant additive increases in collagen per wet weight (4-fold), compressive instantaneous (3-fold) and relaxation (2-fold) moduli, and tensile moduli in the circumferential (4-fold) and radial (6-fold) directions were obtained. Conclusions: This study demonstrates that a stimulation regimen of simultaneous tension and compression mechanical stimulation, C-ABC, and TGF-b1 is able to create anatomic meniscus constructs replicating the compressive mechanica

Effects of a 28-Day Carbohydrate-Restricted Diet on Metabolic and Performance Markers in Professional Firefighters

PURPOSE:Firefighters (FF) experience acute physiological and psychological stressors such as disturbed sleep patterns, frequent snacking, smoke exposure, and intense physical exertion, likely contributing to a significant risk for cardiovascular disease (CVD) and sudden cardiac death. Additionally, FF have high obesity prevalence rates and low cardiovascular fitness levels. Proper dietary and exercise regime interventions may decrease CVD risk. Carbohydrate-restricted diets (CRD) may benefit FF health through increased metabolic flexibility, decreased fat mass, and improved body composition, without negatively affecting the strength and aerobic performance. METHODS:Twenty-one healthy, male professional FF recruited from local fire departments underwent 9 testing sessions: Trials 1-3 were used as familiarizations, Trials 4-6 (15-days later) established a baseline, and Trials 7-9 were performed following a 28-day CRD. The 28-day CRD consisted of a carbohydrate (CHO) restricted (less than 25%/day), caloric ad-libitum diet protocol allowing flexibility and mimicking real-life eating patterns. FF Physical Performance Assessment (FPPA) variables (2.41-km run, pull-ups, push-ups, and sit-ups) were analyzed using dependent t-test. Additionally, substrate oxidation rates for fats and CHO (g·min-1) were measured during Graded Exercise Testing (GXT) at 5 timepoints and analyzed using a 2 x 5 (Treatment x Timepoint) RMANOVA. RESULTS:A significant difference (pp\u3c 0.05). CONCLUSION:The study’s purpose was to examine the effects of a 28-day CRD among FF. The diet increased fat oxidation, decreased CHO oxidation during GXT, and was associated with improved FPPA 2.41-km run time and pull-ups. FF following a CRD can significantly reduce their risk for CVD and improve on-duty performance

Impact of Time Restricted Feeding on Markers of Cardiometabolic Health

Time restricted feeding (TRF) is a form of intermittent fasting in which all calories are consumed within a certain amount of time (i.e. 6-8 hrs) only water is ingested for the remainder of the day. Previous research shows improvements in body composition and some markers of cardiometabolic health, but it is not clear if these results were due to the decreased eating window, or due to a decrease in caloric intake that typically occurs with fasting protocols. PURPOSE: to assess whether a caloric deficit is necessary to achieve improvements in cardiometabolic health as well as evaluate the impact TRF has on blood markers of oxidative stress. METHODS: Participants (n=22) were apparently healthy young men (22 ± 2.5 yrs; 178.4 ± 6.9 cm; 90.3 ± 24 kg) randomized into an iso-caloric group (had to consume the same number of calories as before the study) or an ad libitum group. Both groups participated in a TRF protocol of 8 hours feeding and 16 hours of fasting (water only) daily for 28 days. Before and upon completion of the study, the following measures were taken: blood pressure, body fat percentage, fat mass, fat free mass, insulin, cortisol, growth hormone, glutathione, superoxide dismutase, adiponectin, blood lipid panel, and blood glucose. RESULTS: Both groups demonstrated significantly (pCONCLUSION:A TRF protocol with an 8-hour eating window can improve markers of cardiometabolic health including body composition, blood pressure, lipids, and adiponectin without changing daily caloric intake

Time-restricted feeding for the prevention of cardiometabolic diseases in high-stress occupations: A mechanistic review

© 2019 The Author(s). Published by Oxford University Press on behalf of the International Life Sciences Institute. All rights reserved. Factors such as shift work, poor diet, lack of physical activity, and irregular sleep patterns put men and women employed in high-stress occupations (e.g., firefighters, police officers) at risk for cardiometabolic diseases. Time-restricted feeding (TRF) is a new approach to combatting many of these diseases; it places an emphasis on when meals are consumed, rather than calorie content. By only manipulating the eating window, and without changing the food composition of the diet, research in rodent models has shown promising results that have health implications in people, such as obesity prevention, improved insulin sensitivity, and decreased oxidative stress, inflammation, and cholesterol synthesis. Human trials remain limited and the current data are mixed with regard to TRF and improving health. Present findings suggest the timing of the feeding-fasting window, with feeding taking place in the waking hours and fasting in the evening hours, might offer the greatest benefit for improving cardiometabolic markers. Although additional human trials are needed, TRF might reset and synchronize metabolic clocks found throughout the body that are disturbed with obesity, shift work, and frequent eating. Therefore, TRF might offer an effective feeding-fasting paradigm with significant clinical implications for the management and treatment of cardiometabolic diseases observed in individuals in high-stress occupations in the United States and in the US population in general. This review outlines the current rodent and human evidence in these areas and the efficacy of TRF for improving human health

Exogenous ketone salts do not improve cognitive performance during a dual-stress challenge

© 2020 Human Kinetics, Inc. In the present study, our team aimed to investigate the effects of acute ingestion of a ketone salt (KS) supplement on the cognitive performance in healthy college-aged males during a dual-stress challenge (DSC). Following a peak oxygen uptake test and DSC familiarization, 16 males completed a DSC while cycling at 60% of their respective peak oxygen uptake after ingesting either a commercially available racemic (D- and L-)β-hydroxybutyrate (β-OHB) KS (0.38 g/kg body mass) or a placebo, using a triple-blinded, crossover, and counterbalanced design. The participants consumed the KS or placebo at -60 and -15 min prior to the start of the DSC. Heart rate, rating of perceived exertion, and blood β-OHB and glucose were sampled throughout. The DSC consisted of a mental arithmetic challenge and a modified Stroop Color Word, which alternated every 2 min for 20 min. Upon completion of the DSC, responses for correct, incorrect, and no responses were recorded for the mental arithmetic challenge and Stroop Color Word. Blood β-OHB was elevated with KS by -15 min and remained so throughout (p \u3c -001), peaking at 0.76 ± 0.32 mM. Blood glucose was lower with KS compared with the placebo at -15 and 10 min by 9% and 5%, respectively (both ps \u3c .05). There were no differences between the treatments for heart rate, rating of perceived exertion, mental arithmetic challenge, or Stroop Color Word. Overall, this study suggests that KSs are not effective aids for enhancing cognitive performance during a DSC, which might partially be explained by the inability of currently available commercial KS supplements to elevate β-OHB blood concentrations above ∼1.0 mM