Using Drosophila to Understand Biochemical and Behavioral Responses to Exercise.
Exerc Sport Sci Rev. 2018 Jan 15;:
Authors: Sujkowski A, Wessells R
The development of endurance exercise paradigms in Drosophila has facilitated study of genetic factors that control individual response to exercise. Recent work in Drosophila has demonstrated that activation of octopaminergic neurons is alone sufficient to confer exercise adaptations to sedentary flies. These results suggest that adrenergic activity is both necessary and sufficient to promote endurance exercise adaptations.
PMID: 29346165 [PubMed - as supplied by publisher]
Pacing strategies by age in marathon cross-country skiing.
Phys Sportsmed. 2018 Jan 18;:
Authors: Nikolaidis PT, Knechtle B
OBJECTIVES: Pacing strategies have mainly been investigated for runners, but little is known for cross-country skiers. The aim of the present study was to investigate whether differences in pacing strategies do exist between younger and older cross-country skiers competing in the 42km 'Engadin Ski Marathon'.
METHODS: Pacing was studied in 105,565 cross-country skiers (classified in 5-year age groups) competing between 1998 and 2016 in this race by examining changes of mean section velocity in 10km (Change A, i.e. 100×(velocity in the 10-20km section - velocity in the 0-10km section)/velocity in the 0-10km section), 20km (Change B) and 35km (Change C).
RESULTS: A small sex×distance (i.e. Change A versus Change B versus Change C) interaction on change of velocity was shown (P<.001, η2=0.016), with women showing a less even pacing than men. In women, there was a trivial main effect of age group on Change A (P<.001, η2=0.008) with a smaller decrease in velocity in age group <20 (-7.4%) and larger decrease in velocity in age group 75-79 (-12.8%), and Change B (P=.006, η2=0.004) with smaller increase in velocity in age group 75-79 (+30.6%) and larger increase in velocity in age group 40-44 (+37.7%), but not on Change C (P=.784, η2=0.003). In men, a small main effect of age group on Change A was shown (P<.001, η2=0.019), with a smaller decrease of velocity in age group <20 (-3.5%) and larger in age group 70-74 (-10.5%). Trivial main effects of age group on Change B (P<.001, η2=.002), with a smaller increase of velocity in age group 85-89 (+25.8%) and larger increase in age group 70-74 (+33.0%), and Change C (P<.001, η2=0.003), with smaller decrease of velocity in age group 85-89 (-38.2%) and larger decrease in age group 80-84 (-41.0%), were found.
CONCLUSIONS: Based on these findings, it was concluded that men and young cross-country skiers had a more even pacing than women and older cross-country skiers, which was in contrast with previous findings in other endurance sports, suggesting that the sex- and age-related differences in pacing might be sport-dependent.
PMID: 29345960 [PubMed - as supplied by publisher]
Caffeine Improves Triathlon Performance: A Field Study in Males and Females.
Int J Sport Nutr Exerc Metab. 2018 Jan 18;:1-34
Authors: Potgieter S, Wright HH, Smith C
The ergogenic effect of caffeine on endurance exercise is commonly accepted. We aimed to elucidate realistically the effect of caffeine on triathlon event performance using a field study design, while allowing investigation into potential mechanisms at play. A double-blind, randomized, crossover, field trial was conducted. Twenty-six triathletes (14 males, 12 females) participated (age: 37.8±10.6 years, habitual caffeine intake: 413±505 mg/day, percentage body fat: 14.5±7.2%, training/week: 12.8±4.5 hours). Microencapsulated caffeine (6 mg/kg body weight) was supplemented 60 minutes pre-trial. Performance data included time to completion (TTC), rating of perceived exertion (RPE) and profile of mood states (POMS). Blood samples taken before, during and post-race were analyzed for cortisol, testosterone and full blood count. Capillary blood lactate concentrations were assessed pre-race, during transitions and 3, 6, 9, 12, 15 minutes after triathlons. Caffeine supplementation resulted in a 3.7% reduction in swim time (33.5±7.0 vs. 34.8±8.1 minutes, p<0.05) and a 1.3% reduction in TTC (149.6±19.8 vs. 151.5±18.6 minutes, p<0.05) for the whole group. Gender differences and individual responses are also presented. Caffeine did not alter RPE significantly, but better performance after caffeine supplementation suggests a central effect resulting in greater overall exercise intensity at the same RPE. Caffeine supplementation was associated with higher post-exercise cortisol levels (665±200 vs. 543±169 nmol/l, p<0.0001) and facilitated greater peak blood lactate accumulation (ANOVA main effect, p<0.05). We recommend that triathlon athletes with relatively low habitual caffeine intake may ingest 6 mg/kg body weight caffeine, 45-60 minutes before the start of Olympic-distance triathlon in order to improve performance.
PMID: 29345161 [PubMed - as supplied by publisher]
Effects of hereditary moderate high fat diet on metabolic performance and physical endurance capacity in C57BL/6 offspring.
Mol Med Rep. 2018 Jan 16;:
Authors: Liu F, Zhang G, Sheng X, Liu S, Cui M, Guo H, Xue J, Zhang L
Obesity in pregnant women presents a risk to fetal health, leading to numerous metabolic syndromes and chronic inflammation risks. Previously, physical exercise was considered to be one of the primary treatments for obesity. However, the effect of fat consumption throughout the life cycle on physical endurance capacity remains unknown. A total of two groups of female mice (age, 6 weeks; C57BL/6J) were fed with a normal chow diet and a moderate high fat diet (MHFD), during pregnancy and lactation (8 weeks), with the offspring receiving the same diet as the mother. When filial mice were 8, 16 and 24 weeks old, they were tested for endurance, blood pressure (BP) and glucose tolerance, as well as adipose tissue infiltration and macrophage subtype. Compared with the control group, filial mice in MHFD groups exhibited increased BP and glucose levels and larger adipose cells (~4‑fold). During adolescence, the obese filial mice demonstrated increased endurance compared with controls. Endurance declines in middle and old age; the endurance of aged obese mice was 29% that of lean ones. In addition, body coordination and movement memory did not notably change. The expression of cluster of differentiation 68, one of the most reliable markers of macrophages, increased by 2.48‑fold, demonstrating that macrophages were recruited and underwent infiltration. In addition, increased tumor necrosis factor‑α and decreased interleukin‑10 expression demonstrated that infiltrated macrophages are polarized to the M1 state, which weakens physical endurance and resists type M2 macrophages, which exhibit repairing functions. In conclusion, hereditary MHFD weakens physical endurance and alters the metabolic characteristics of C57BL/6 offspring.
PMID: 29344657 [PubMed - as supplied by publisher]
Understanding the factors that effect maximal fat oxidation.
J Int Soc Sports Nutr. 2018;15:3
Authors: Purdom T, Kravitz L, Dokladny K, Mermier C
Lipids as a fuel source for energy supply during submaximal exercise originate from subcutaneous adipose tissue derived fatty acids (FA), intramuscular triacylglycerides (IMTG), cholesterol and dietary fat. These sources of fat contribute to fatty acid oxidation (FAox) in various ways. The regulation and utilization of FAs in a maximal capacity occur primarily at exercise intensities between 45 and 65% VO2max, is known as maximal fat oxidation (MFO), and is measured in g/min. Fatty acid oxidation occurs during submaximal exercise intensities, but is also complimentary to carbohydrate oxidation (CHOox). Due to limitations within FA transport across the cell and mitochondrial membranes, FAox is limited at higher exercise intensities. The point at which FAox reaches maximum and begins to decline is referred to as the crossover point. Exercise intensities that exceed the crossover point (~65% VO2max) utilize CHO as the predominant fuel source for energy supply. Training status, exercise intensity, exercise duration, sex differences, and nutrition have all been shown to affect cellular expression responsible for FAox rate. Each stimulus affects the process of FAox differently, resulting in specific adaptions that influence endurance exercise performance. Endurance training, specifically long duration (>2 h) facilitate adaptations that alter both the origin of FAs and FAox rate. Additionally, the influence of sex and nutrition on FAox are discussed. Finally, the role of FAox in the improvement of performance during endurance training is discussed.
PMID: 29344008 [PubMed - in process]
A community-based exercise program to increase participation in physical activities among youth with disability: a feasibility study.
Disabil Rehabil. 2018 Jan 17;:1-8
Authors: Shields N, van den Bos R, Buhlert-Smith K, Prendergast L, Taylor N
PURPOSE: To evaluate the feasibility of a student-mentored community-based exercise program for youth with disability.
METHOD: Nineteen youth (nine female; mean age 18 years) with disability (seven cerebral palsy, six Down syndrome, three spina bifida, two autism spectrum disorder, one spinal cord injury) were recruited. Each participant was matched with a student mentor and exercised twice a week for 12 weeks at their local gymnasium. Five domains of feasibility were assessed: demand, implementation, practicality, limited efficacy testing, and acceptability.
RESULTS: Demand comprised 55 expressions of interest. Demonstrating evidence of implementation, 91% of scheduled sessions were attended and training fidelity (comparing training load in weeks 1 and 12) showed exercise intensity significantly increased for strength and aerobic exercises. The program was practical with no major and 17 minor adverse events (e.g., muscle soreness). Limited efficacy testing was demonstrated by increased arm (4 kg, 95% CI: 1-7) and leg strength (43 kg, 95% CI: 24-62), walking endurance (80 m, 95% CI: 24-137), and improvement in three dimensions of health-related quality of life (autonomy, physical, and psychological well-being). The program was accepted very positively by participants.
CONCLUSIONS: A student-mentored community-based exercise program feasibly engages youth with disability in community-based exercise. Implications for Rehabilitation A 12-week community-based student-mentored exercise program for youth with disability is feasible. Exercising in a real-world setting with a student mentor has a positive effect on physical and psychological well-being of youth with disability.
PMID: 29343130 [PubMed - as supplied by publisher]
Interstitial Glucose and Physical Exercise in Type 1 Diabetes: Integrative Physiology, Technology, and the Gap In-Between.
Nutrients. 2018 Jan 15;10(1):
Authors: Moser O, Yardley JE, Bracken RM
Continuous and flash glucose monitoring systems measure interstitial fluid glucose concentrations within a body compartment that is dramatically altered by posture and is responsive to the physiological and metabolic changes that enable exercise performance in individuals with type 1 diabetes. Body fluid redistribution within the interstitial compartment, alterations in interstitial fluid volume, changes in rate and direction of fluid flow between the vasculature, interstitium and lymphatics, as well as alterations in the rate of glucose production and uptake by exercising tissues, make for caution when interpreting device read-outs in a rapidly changing internal environment during acute exercise. We present an understanding of the physiological and metabolic changes taking place with acute exercise and detail the blood and interstitial glucose responses with different forms of exercise, namely sustained endurance, high-intensity, and strength exercises in individuals with type 1 diabetes. Further, we detail novel technical information on currently available patient devices. As more health services and insurance companies advocate their use, understanding continuous and flash glucose monitoring for its strengths and limitations may offer more confidence for patients aiming to manage glycemia around exercise.
PMID: 29342932 [PubMed - in process]