Sex differences in the physiological responses to exercise-induced dehydration: Consequences and mechanisms?

2021 ◽  
Author(s):  
Kate Aiko Wickham ◽  
Devin G. McCarthy ◽  
Lawrence L. Spriet ◽  
Stephen S. Cheung
Keyword(s):  
Sex Differences ◽  
Mass Loss ◽  
Body Mass ◽  
Sweat Gland ◽  
Body Water ◽  
Physiological Strain ◽  
Body Mass Loss ◽  
Cardiac Strain ◽  
Exercise Onset ◽  
Exercise Induced

Physiological strain during exercise is increased by mild dehydration (~1-3% body mass loss). This response may be sex-dependent but there are no direct comparative data in this regard. This review aimed to develop a framework for future research by exploring the potential impact of sex on thermoregulatory and cardiac strain associated with exercise-induced dehydration. Sex-based comparisons were achieved by comparing trends from studies that implemented similar experimental protocols but recruited males and females separately. This revealed a higher core temperature (Tc) in response to exercise-induced dehydration in both sexes, however it seemingly occurred at a lower percent body mass loss in females. Although less clear, similar trends existed for cardiac strain. The average female may have a lower body water volume per body mass compared to males, and therefore the same % body mass loss between the sexes may represent a larger portion of total body water in females potentially posing a greater physiological strain. Additionally, the rate which Tc increases at exercise onset might be faster in females and induce a greater thermoregulatory challenge earlier into exercise. The Tc response at exercise onset is associated with lower sweating rates in females, which is commonly attributed to sex-differences in metabolic heat production. However, a reduced sweat gland sensitivity to stimuli, lower fluid output per sweat gland, and sex hormones promoting fluid retention in females may also contribute. In conclusion, the limited evidence suggests sex-based differences exist in thermoregulatory and cardiac strain associated with exercise-induced dehydration, and this warrants future investigations.

scholarly journals Impact of Exercise-induced Dehydration on Perceived Exertion During Endurance Exercise: A Systematic Review with Meta-analysis

2021 ◽  
Author(s):  
Thomas A Deshayes ◽  
Timothee Pancrate ◽  
Eric DB Goulet
Keyword(s):  
Mass Loss ◽  
Body Mass ◽  
Endurance Exercise ◽  
Perceived Exertion ◽  
Meta Analysis ◽  
Exercise Adherence ◽  
Rating Of Perceived Exertion ◽  
Body Mass Loss ◽  
Exercise Induced ◽  
The Impact

Understanding the impact of stressors on the rating of perceived exertion (RPE) is relevant from a performance and exercise adherence/participation standpoint. Athletes and recreationally active individuals dehydrate during exercise. No attempt has been made to systematically determine the impact of exercise-induced dehydration (EID) on RPE. The present meta-analysis aimed to determine the effect of EID on RPE during endurance exercise and examine the moderating effect of potential confounders using a meta-analytical approach. Data analyses were performed on raw RPE values using random-effects models weighted mean effect summaries and meta-regressions with robust standard errors, and with a practical meaningful effect set at 1 point difference between euhydration (EUH) and EID. Only controlled crossover studies measuring RPE with a Borg scale in healthy adults performing ≥ 30 min of continuous endurance exercise while dehydrating or drinking to maintain EUH were included. Sixteen studies were included, representing 147 individuals. Mean body mass loss with EUH was 0.5 ± 0.4%, compared to 2.3 ± 0.5% with EID (range 1.7 to 3.1%). Within an EID of 0.5 to 3% body mass, a maximum difference in RPE of 0.81 points (95% CI: 0.36-1.27) was observed between conditions. A meta-regression revealed that RPE increases by 0.21 points for each 1% increase in EID (95% CI: 0.12-0.31). Humidity, ambient temperature and aerobic capacity did not alter the relationship between EID and RPE. Therefore, the effect of EID on RPE is unlikely to be practically meaningful until a body mass loss of at least 3%.

23 Nutritional Intake and Weight Change in Severely Burned Patients

2021 ◽  
Vol 42 (Supplement_1) ◽  
pp. S20-S21
Author(s):  
Sandrine O Fossati ◽  
Beth A Shields ◽  
Renee E Cole ◽  
Adam J Kieffer ◽  
Saul J Vega ◽  
...  
Keyword(s):  
Wound Healing ◽  
Mass Loss ◽  
Performance Improvement ◽  
Body Mass ◽  
Total Body Surface Area ◽  
Nutritional Intake ◽  
Energy Deficit ◽  
Body Mass Loss ◽  
Improvement Project ◽  
Burn Care

Abstract Introduction Nutrition is crucial for recovery from burn injuries, as severe weight (wt.) loss can lead to impaired immunity and wound healing, infections, skin graft failure, and mortality. Previous studies recommended avoiding more than 10% wt. loss, as this level resulted in increased infection rates. However, wt. loss is often not quantifiable during the critical illness phase, with severe edema masking non-fluid related body wt. changes. Energy (kcal) deficits can be used to estimate wt. loss until the edema has resolved, but previous studies in non-burn patients indicate that actual wt. loss is less than the commonly used 3500 kcal per pound of fat (7700 kcal per kg of fat). The objective of this performance improvement project was to evaluate nutritional intake and the resulting dry wt. change in severely burned patients. Methods This performance improvement project was approved by our regulatory compliance division. We performed a retrospective evaluation on patients with at least 20% total body surface area (TBSA) burns admitted for initial burn care to our intensive care unit over a 7-year period. Patients who died or who had major fascial excisions or limb amputations were excluded. Patients who did not achieve a recorded dry wt. after wound healing were not included in this analysis. Retrospective data were collected, including sex, age, burn size, kcal intake, kcal goal per the Milner equation using activity factor of 1.4, admission dry wt., dry wt. after wound healing (defined as less than 10% TBSA open wound), and days to dry wt. after wound healing. Descriptive statistics and linear regression were performed using JMP. Significance was set at p< 0.05. Results The 30 included patients had the following characteristics: 90% male, 30 ± 11 years old, 45% ± 15% TBSA burn. They received 2720 ± 1092 kcal/day, meeting 68% ± 24% kcal goal, and took approximately 53 ± 30 days from injury to achieve dry wt. after wound healing. These patients had wt. loss of 8 ± 8 kg from the kcal deficit of 69,819 ± 51,704 during this time period. The kcal deficit was significantly associated with wt. change [p < 0.001, R2 = 0.49, wt. change in kg = (-0.000103 x kcal deficit) – 1]. This translates to one kg of body wt. loss resulting from 9709 kcal deficit. Conclusions This performance improvement project found that an energy deficit of approximately 9700 kcal in our patients equates to 1 kg of body mass loss (4400 kcal deficit equates to 1 pound of body mass loss). These findings are similar to wt. loss studies in other patient populations and contrary to the commonly used 3500 kcal per pound of fat (7700 kcal per kg of fat).

scholarly journals Simulated model of obesity and immediate metabolic disorders after gastric shunting with anastomosis in small laboratory animals

2020 ◽  
Vol 87 (9-10) ◽  
pp. 84-88
Author(s):  
R. I. Vynogradov ◽  
O. S. Tyvonchuk ◽  
K. O. Nadiein ◽  
V. V. Moskalenko
Keyword(s):  
Small Intestine ◽  
Mass Loss ◽  
Body Mass ◽  
Metabolic Disorders ◽  
Metabolic Changes ◽  
Experimental Simulation ◽  
Body Mass Loss ◽  
Simulated Model ◽  
Group I ◽  
Group Ii

Objective. To study metabolic changes and peculiarities of mineral balance depending on the common loop length while constructing of the simulated model of gastric shunting with one anastomosis during 60 days. Materials and methods. Experimental simulation of gastric minishunting with one anastomosis of various length of bilio-pancreatic loop was constructed on the rats. In 10 rats the anastomosis was formatted on level of half of total length of small intestine (Group I), and also in 10 - a third part of general length of small intestine (Group II). Control Group consisted of 5 rats. The indices of the extra body mass loss and metabolic changes were compared. Results. In the rats of Group I the index of the body mass loss have constituted 16.6% (41.7 gm), and of the Group II -20.6% (53.2 gm). Lowering of indices of mineral and prion metabolism, comparing preoperative values, was observed in both Groups. Dystrophic changes in osseous tissue of vertebral bodies of lumbar vertebral column were noted in animals of both Groups, more pronounced - in Group II. Conclusion. The protein and mineral metabolism disorders may be observed not only in large resection volume, but in exclusion of half and more segment of small bowel from general transit, using gastric shunting, what lacks significant advantages in the extra body mass loss, but leads to more profound metabolic disorders.

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