scholarly journals Accounting for the Nutritional Context to Correctly Interpret Results from Studies of Exercise and Sedentary Behavior

Nutrients ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 2230
Author(s):  
Barry Braun ◽  
Alissa Newman

There is a wealth of research lauding the benefits of exercise to oppose cardiometabolic disease such as diabetes, CVD and hypertension. However, in the great majority of these studies, the nutritional context (energy balance, deficit, or surplus) has been ignored, despite its profound effect on responses to both exercise and inactivity. Even a minor energy deficit or surplus can strongly modulate the magnitude and duration of the metabolic responses to an intervention; therefore, failure to account for this important confounding variable obscures clear interpretation of the results from studies of exercise or inactivity. The aim of this review is to highlight key lessons from studies examining the interaction between exercise and sedentary behavior, energy status, and glucose and insulin regulation. In addition to identifying notable problems, we suggest a few potential solutions.

2020 ◽  
Author(s):  
Pinghui Yu ◽  
Ning Jiang ◽  
Weimeng Fu ◽  
Guangjie Zheng ◽  
Guangyan Li ◽  
...  

Abstract Background: Glutathione (GSH) is important for plants to resist abiotic stress, and a large amount of energy is required in the process. However, it is not clear how the energy status affects the accumulation of GSH in plants under cold stress. Results: Two rice pure lines, Zhongzao39 (ZZ39) and its recombinant inbred line 82 (RIL82) were subjected to cold stress for 48 h. Under cold stress, RIL82 suffered more damages than ZZ39 plants, in which higher increases in APX activity and GSH content were showed in the latter than the former compared with their respective controls. This indicated that GSH was mainly responsible for the different cold tolerance between these two rice plants. Interestingly, under cold stress, greater increases in contents of carbohydrate, NAD(H), NADP(H) and ATP as well as the expression levels of GSH1 and GSH2 were showed in RIL82 than ZZ39 plants. In contrast, ATPase content in RIL82 plants was adversely inhibited by cold stress while it increased significantly in ZZ39 plants. This indicated that cold stress reduced the accumulation of GSH in RIL82 plants mainly due to the inhibition on ATP hydrolysis rather than energy deficit. Conclusion: We inferred that the energy status determined by ATP hydrolysis involved in regulating the cold tolerance of plants by controlling GSH synthesis.


Author(s):  
Bradley E. Alger

This chapter reports original data from two surveys conducted to find out how scientists view the hypothesis and related concepts. One was an online survey of hundreds of members of biological research societies. The scientists reported on their knowledge of and training in the use of the hypothesis, their views about hypothesis testing as compared with other modes of conducting science, such as Discovery Science, open-ended questioning, and Big Data methods. Respondents estimated how the various scientific modes influenced their work and how much they relied on each one. Most respondents,70% of them, reported having received little or no training in scientific thinking; however, 90% felt confident about their thinking skills. Nevertheless, more than 90% felt that formal training in this area would be helpful. The great majority relied on hypotheses in their research work. The second survey, analyzed all (more than 150) neuroscience research papers that appeared sequentially in top journals during 2015 to determine how the papers were structured, particularly with respect to the hypothesis. Only 33% of the papers had an explicitly stated hypothesis, whereas, in 45%, the hypothesis was “implicit.” A minor, though notable, fraction of the papers misused the term “hypothesis.” The results are germane to several topics covered in the remainder of the book.


2015 ◽  
Vol 27 (1) ◽  
pp. 30-33
Author(s):  
Alon Eliakim

Introduction:Competitive female athletes restrict energy intake and increase exercise energy expenditure frequently resulting in ovarian suppression. The purpose of this study was to determine the impact of ovarian suppression and energy deficit on swimming performance (400-m swim velocity).Methods:Menstrual status was determined by circulating estradiol (E2) and progesterone (P4) in ten junior elite female swimmers (15-17 yr). The athletes were categorized as cyclic (CYC) or ovarian-suppressed (OVS). They were evaluated every 2 weeks for metabolic hormones, bioenergetic parameters, and sport performance during the 12-week season.Results:CYC and OVS athletes were similar (p > .05) in age (CYC = 16.2 ± 1.8 yr, OVS = 17 ± 1.7 yr), body mass index (CYC = 21 ± 0.4 kg·m, OVS = 25 ± 0.8 kg·m), and gynecological age (CYC = 2.6 ± 1.1 yr, OVS = 2.8 ± 1.5 yr). OVS had suppressed P4 (p < .001) and E2 (p = .002) across the season. Total triiodothyronine (TT3) and insulin-like growth factor (IGF-1) were lower in OVS (TT3: CYC = 1.6 ± 0.2 nmol·L, OVS = 1.4 ± 0.1 nmol·L, p < .001; IGF-1: CYC = 243 ± 1 μg·mL, OVS = 214 μg·mL p < .001) than CYC at week 12. Energy intake (p < .001) and energy availability (p < .001) were significantly lower in OVS versus CYC. OVS exhibited a 9.8% decline in Δ400-m swim velocity compared with an 8.2% improvement in CYC at week 12.Conclusions:Ovarian steroids (P4 and E2), metabolic hormones (TT3 and IGF-1), and energy status markers (EA and EI) were highly correlated with sport performance. This study illustrates that when exercise training occurs in the presence of ovarian suppression with evidence for energy conservation (i.e., reduced TT3), it is associated with poor sport performance. These data from junior elite female athletes support the need for dietary periodization to help optimize energy intake for appropriate training adaptation and maximal sport performance


2020 ◽  
Author(s):  
Pinghui Yu ◽  
Ning Jiang ◽  
Weimeng Fu ◽  
Guangjie Zheng ◽  
Guangyan Li ◽  
...  

Abstract Background Glutathione (GSH) is important for plants to resist against abiotic stress, and a large amount of energy is required in the process. However, it is not clear how the energy status affects the accumulation of GSH in plants under cold stress. Results Two rice genotypes, Zhongzao39 (ZZ39) and its recombinant inbred line 82 (RIL82) were subjected to cold stress for 48 h. Under cold stress, RIL82 suffered more damages than ZZ39 plants, in which the latter had higher increases in APX activity and GSH content than the former compared with their respective controls. This indicated that GSH was mainly responsible for the different cold tolerance between these two rice plants. Interestingly, under cold stress, greater increases in contents of carbohydrate, NAD(H), NADP(H) and ATP as well as the expression levels of GSH1 and GSH2 were showed in RIL82 than ZZ39 plants. In contrast, ATPase activity in RIL82 plants was adversely inhibited by cold stress while it significantly increased in ZZ39 plants. This indicated that cold stress reduced the accumulation of GSH in RIL82 plants mainly due to the inhibition on ATP hydrolysis rather than energy deficit. Conclusion We inferred that the energy status determined by ATP hydrolysis involved in regulating the cold tolerance of plants by controlling GSH synthesis.


1990 ◽  
Vol 38 (3B) ◽  
pp. 541-554 ◽  
Author(s):  
H. Everts

In 6 feeding trials with pregnant ewes, blood glucose concentrations were affected by litter size after day 84 of pregnancy. An increase in litter size decreased blood glucose during the last phase of pregnancy. At day 141 a sharp increase in glucose was seen. Ewes with ketosis had after day 126 of pregnancy a significant lower glucose concentration. beta -Hydroxybutyrate (BHB) and non-esterified fatty acids (NEFA) were also affected by litter size in the last months of pregnancy. With increasing litter size BHB increased more dramatically than NEFA concentrations. Ewes with ketosis had higher BHB and NEFA concentrations in the last month of pregnancy. Ewes on treatments with a higher metabolizable energy (ME) intake (rations with 60% of the energy originating from concentrates) had a higher glucose, a lower BHB and a lower NEFA concentration in the last month of pregnancy than ewes given a diet with 40% of the energy originating from concentrates. A lower incidence of ketosis on treatments with a higher energy intake was expected, but not seen. Probably, energy deficit is not the only factor inducing ketosis. With regression models the energy requirement of pregnant ewes with a body weight of about 85 kg during the last month of pregnancy was estimated. ME requirement in MJ per day for a ewe with a single, twin, triplet, quadruplet and quintuplet was 13.0, 15.9, 17.1, 18.4 and 19.1, respectively. The estimated energetic efficiency of conceptus growth was about 0.16. (Abstract retrieved from CAB Abstracts by CABI’s permission)


Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Todd F. Hutchinson ◽  
Michael C. Stambaugh ◽  
Joseph M. Marschall ◽  
Richard P. Guyette

Abstract Background Knowledge of historical fire regimes informs the restoration of woodland communities. In the Appalachian Plateau of Ohio and Kentucky, USA, little is known about the long-term history of fire in oak–pine communities, which are declining in the region. To address this knowledge gap, two sites with remnant fire-scarred yellow pines, Hatton Ridge in Kentucky and McAtee Run in Ohio, were studied to document aspects of the historical fire regime. Cross-sections from fire-scarred yellow pines were collected. Fire chronologies were constructed and fire intervals were calculated using standard dendrochronological methods. Results Fires, the great majority of which occurred in the dormant season, were frequent at both sites from circa 1750 at Hatton and 1800 at McAtee, until the suppression period (1930 to present); only one fire was recorded after 1930. Mean fire intervals (MFI) for the entire period were nearly identical, 4.7 and 4.4 years at Hatton and McAtee, respectively. At both sites, MFIs were lowest in the industrial period (1850 to 1930). At Hatton, the MFI was 6.6 years before 1850 and 3.5 years from 1850 to 1930, while at McAtee, the MFI was 8.4 years before 1850 and 2.7 years from 1850 to 1930. At both sites, the occurrence of fire was not more frequent than expected in years associated with a drought. At McAtee, the majority of pine establishment occurred in pulses during two periods, 1770 to 1781 and 1853 to 1867, suggesting stand-scale canopy disturbances; the second pulse was associated with frequent burning. In contrast, large pulses of pine establishment were not found at Hatton. Conclusions Yellow pines were a component of these communities, which experienced frequent fire for at least 130 to 160 years. After more than 70 years with little or no fire, yellow pines are now a minor component of the overstory and pine regeneration is essentially absent. Although intensive management with partial harvesting and frequent fire would be required to restore oak–pine woodlands on appropriate sites, it would serve to sustain these increasingly uncommon communities.


1974 ◽  
Vol 1 (4) ◽  
pp. 149-157 ◽  
Author(s):  
D. B. Johnson

A sample of 62 cases of supernumerary teeth found in the lateral incisor area was selected and analysed. The great majority of these teeth were supplemental teeth, with deciduous precedents. Both teeth (the normal incisor and supernumerary) showed reduction in size as compared to the unaffected side. Differences were found between the mesial unit and the distal—the mesial being larger and having an incisor shape and the distal smaller and resembling a canine. Many of the pairs were similar to supernumerary teeth found in cleft lip and palate and there were also effects upon the other teeth particularly central incisors. Stigmata of cleft were observed in the alveolus, nasal floor and hard palate in a significant proportion of cases. It is concluded that supernumerary laterals arise by gemination or failure of development of normal odontogenic material. The anomaly fulfils the hypothetical criteria for a microform of cleft and may be the result of a minor error in embryonic fusion.


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