Objective: This systematic review aimed to critically analyze the literature to determine how high-intensity intermittent training(HIIT) affects recreational endurance runners in the short-and long-term.Methods: Elect...Objective: This systematic review aimed to critically analyze the literature to determine how high-intensity intermittent training(HIIT) affects recreational endurance runners in the short-and long-term.Methods: Electronic databases were searched for literature dating from January 2000 to October 2015. The search was conducted using the key words "high-intensity intermittent training" or "high-intensity interval exercise" or "interval running" or "sprint interval training" and "endurance runners" or "long distance runners". A systematic approach was used to evaluate the 783 articles identified for initial review. Studies were included if they investigated HIIT in recreational endurance runners. The methodological quality of the studies was evaluated using the Physiotherapy Evidence Database(PEDro) scale(for intervention studies) and the modified Downs and Black Quality Index(for cross-sectional studies).Results: Twenty-three studies met the inclusionary criteria for review. The results are presented in 2 parts: cross-sectional(n = 15) and intervention studies(n = 8). In the 15 cross-sectional studies selected, endurance runners performed at least 1 HIIT protocol, and the acute impact on physiological, neuromuscular, metabolic and/or biomechanical variables was assessed. Intervention studies lasted a minimum of 4 weeks, with 10 weeks being the longest intervention period, and included 2 to 4 HIIT sessions per week. Most of these studies combined HIIT sessions with continuous run(CR) sessions; 2 studies' subjects performed HIIT exclusively.Conclusion: HIIT-based running plans(2 to 3 HIIT sessions per week, combining HIIT and CR runs) show athletic performance improvements in endurance runners by improving maximal oxygen uptake and running economy along with muscular and metabolic adaptations. To maximize the adaptations to training, both HIIT and CR must be part of training programs for endurance runners.展开更多
The development of the cotton fiber is very sensitive to temperature variation, and high temperature stress often causes reduced fiber yield and fiber quality. Short-term high temperature stress often occurs during co...The development of the cotton fiber is very sensitive to temperature variation, and high temperature stress often causes reduced fiber yield and fiber quality. Short-term high temperature stress often occurs during cotton production, but little is known about the specific timing and duration of stress that affects fiber development. To make this clear, pot experiments were carried in 2014 and 2015 in a climate chamber using cotton cultivars HY370WR（less sensitive variety） and Sumian 15（heat sensitive variety）, which present different temperature sensitivities. Changes of the most important fiber quality indices（i.e., fiber length, fiber strength and marcironaire） and three very important fiber development components（i.e., cellulose, sucrose and callose） were analyzed to define the time window and critical duration to the high temperature stress at 34°C（max38°C/min30°C）. When developing bolls were subjected to 5 days of high temperature stress at different days post-anthesis（DPA）, the changes（Δ%） of fiber length, strength and micronire, as a function of imposed time followed square polynomial eq. as y=a＋bx＋cx^2, and the time around 15 DPA was the most sensitive period for fiber quality development in response to heat stress. When 15 DPA bolls were heat-stressed for different durations（2, 3, 4, 5, 6, 7 days）, the changes（Δ%） of fiber length, strength and micronire, as a function of stress duration followed logistic equations y=A_1-A_2/1＋（x/x_0）~p＋A_2. Referred to that 5, 10 and 15% are usually used as criteria to decide whether techniques are effective or changes are significant in crop culture practice and reguard to the fiber quality indices change range, we suggested that 5% changes of the major fiber quality indices（fiber length, fiber strength and micronaire） and 10% changes of fiber development components（cellulose, sucrose and callose） could be taken as criteria to judge whether fiber development and fiber quality have been significantly affected by high temperature stress. The key time window for cotton fiber development in response to the high temperature stress was 13–19 DPA, and the critical duration was about 5 days.展开更多
In this study, we investigated the effect of sodium bicarbonate (NaHCO3) supplementation at a dose of 0.2 g·kg−1 40 min before an exercise on intermittent endurance performance and gastrointestina...In this study, we investigated the effect of sodium bicarbonate (NaHCO3) supplementation at a dose of 0.2 g·kg−1 40 min before an exercise on intermittent endurance performance and gastrointestinal distress. The participants were six healthy male students of a university. The Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2) was used for the evaluation of intermittent endurance. The participants ingested water (Cont) or NaHCO3 independently at three timings. After drinking water, the Yo-Yo IR1 was performed for 2 min as warm-up. After resting for 5 min, the Yo-Yo IR2 was initiated. The measurement items were exercise distance, nutrition intake, biochemical test results, and blood gas analysis findings. The participants who ingested NaHCO3 had a 14% extended distance than those who ingested Cont, and 2/3 of those who took NaHCO3 showed a better motor performance. No significant difference was observed between the participants who took Cont and NaHCO3 in terms of pH level at baseline, and the NaHCO3 level was significantly higher during pre- and post-exercise (p 3 in terms of bicarbonate ion level at baseline, and the NaHCO3 level was significantly higher during pre- and post-exercise (p 3 at a low dose (0.2 g·kg−1), their exercise ability during an intermittent endurance test has improved. Furthermore, when digestive absorption is considered, eating a meal in advance may be able to suppress the onset of gastrointestinal distress.展开更多
Fuel cell is a device that converts the chemical energy in the reactants into the electrical energy after steps of sequential electrochemical processes with no significant impact on the environment. For high altitude ...Fuel cell is a device that converts the chemical energy in the reactants into the electrical energy after steps of sequential electrochemical processes with no significant impact on the environment. For high altitude long endurance (HALE) of unmanned aircraft system (UAS) where fuel cell operates as a prime source of power, the operation and performance of a PEM fuel cell at different level of altitudes is vitally important. In this paper, the impact of direct using extracted air from high altitudes atmosphere in order to feed the stack is investigated, and the governing equations of the supplied air and oxygen to the PEM fuel cell stack are developed. The impact of high altitudes upon the operation and the consumption of air are determined in order to maintain certain level of delivered power to the load. Also the implications associated with operating the PEM fuel cell stack at high altitudes and different technical solutions are proposed. Various modes of Integral, Proportional-Integral, and Proportional-Integral-Derivative controller are introduced and examined for different time setting responses in order to determine the most adequate trade-off choice between fast response and reactants consumption which provides the necessary optimization of the air consumption for the developed model of PEM fuel cell used for UAS operation.展开更多
Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive the...Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive thermal management. In this paper, a multi-node transient thermal model for airborne electronic equipment is set up based on the thermal network method to predict their dynamic temperature responses under high altitude and long flight time conditions. Some relevant factors are considered into this temperature prediction model including flight environment,radiation, convection, heat conduction, etc. An experimental chamber simulating a high altitude flight environment was set up to survey the dynamic thermal responses of airborne electronic equipment in a UAV. According to the experimental measurement results, the multi-node transient thermal model is verified without consideration of the effects of flight speed. Then, a modified way about outside flight speed is added into the model to improve the temperature prediction performance. Finally, the corresponding simulation code is developed based on the proposed model. It can realize the dynamic temperature prediction of airborne electronic equipment under HALE conditions.展开更多
To study the high-fat-diet induced rat obesity and the of fect of endurance training on the body fat content of obese rats, we randomly divided 66 male weanling SD rats into control(16 rats) and high fat diet group(50...To study the high-fat-diet induced rat obesity and the of fect of endurance training on the body fat content of obese rats, we randomly divided 66 male weanling SD rats into control(16 rats) and high fat diet group(50 rats). After 10 weeks, we chose diet-induced obese rats(DIO, 26 rats) and divided them into endurance training group(DIO-T, 8 rats) and DIO groups(DIO, 18 rats) randomly. Aner 8 weeks, endurance training, all rats were killed. The results showed that nosignificant difference was found between groups in body weight, the feed efficiency of DIO groups was higher than control groups, tke carass fat con tent of DIO-T group was significantlylower than DIO group, and plasma insulin concentration of DIO group was higher than control and DIO-T groups. It was suggested that rats’ obesity was induced obesity by high fat diet, dietary obesity had relation to higher eding efficiency and hyperinsulinemia. Endurance training can effectively reduce the body fat content of high-fat-diet induced obese rats by improving its hyper-insulinemia. Plasma TCH and TG of all rats had no significant difference.展开更多
基金the University of Jaén for its support to the present study
文摘Objective: This systematic review aimed to critically analyze the literature to determine how high-intensity intermittent training(HIIT) affects recreational endurance runners in the short-and long-term.Methods: Electronic databases were searched for literature dating from January 2000 to October 2015. The search was conducted using the key words "high-intensity intermittent training" or "high-intensity interval exercise" or "interval running" or "sprint interval training" and "endurance runners" or "long distance runners". A systematic approach was used to evaluate the 783 articles identified for initial review. Studies were included if they investigated HIIT in recreational endurance runners. The methodological quality of the studies was evaluated using the Physiotherapy Evidence Database(PEDro) scale(for intervention studies) and the modified Downs and Black Quality Index(for cross-sectional studies).Results: Twenty-three studies met the inclusionary criteria for review. The results are presented in 2 parts: cross-sectional(n = 15) and intervention studies(n = 8). In the 15 cross-sectional studies selected, endurance runners performed at least 1 HIIT protocol, and the acute impact on physiological, neuromuscular, metabolic and/or biomechanical variables was assessed. Intervention studies lasted a minimum of 4 weeks, with 10 weeks being the longest intervention period, and included 2 to 4 HIIT sessions per week. Most of these studies combined HIIT sessions with continuous run(CR) sessions; 2 studies' subjects performed HIIT exclusively.Conclusion: HIIT-based running plans(2 to 3 HIIT sessions per week, combining HIIT and CR runs) show athletic performance improvements in endurance runners by improving maximal oxygen uptake and running economy along with muscular and metabolic adaptations. To maximize the adaptations to training, both HIIT and CR must be part of training programs for endurance runners.
基金funded by the National Natural Science Foundation of China(31271654,31471444)the Natural Science Foundation of Jiangsu Province,China(BK20131318)
文摘The development of the cotton fiber is very sensitive to temperature variation, and high temperature stress often causes reduced fiber yield and fiber quality. Short-term high temperature stress often occurs during cotton production, but little is known about the specific timing and duration of stress that affects fiber development. To make this clear, pot experiments were carried in 2014 and 2015 in a climate chamber using cotton cultivars HY370WR（less sensitive variety） and Sumian 15（heat sensitive variety）, which present different temperature sensitivities. Changes of the most important fiber quality indices（i.e., fiber length, fiber strength and marcironaire） and three very important fiber development components（i.e., cellulose, sucrose and callose） were analyzed to define the time window and critical duration to the high temperature stress at 34°C（max38°C/min30°C）. When developing bolls were subjected to 5 days of high temperature stress at different days post-anthesis（DPA）, the changes（Δ%） of fiber length, strength and micronire, as a function of imposed time followed square polynomial eq. as y=a＋bx＋cx^2, and the time around 15 DPA was the most sensitive period for fiber quality development in response to heat stress. When 15 DPA bolls were heat-stressed for different durations（2, 3, 4, 5, 6, 7 days）, the changes（Δ%） of fiber length, strength and micronire, as a function of stress duration followed logistic equations y=A_1-A_2/1＋（x/x_0）~p＋A_2. Referred to that 5, 10 and 15% are usually used as criteria to decide whether techniques are effective or changes are significant in crop culture practice and reguard to the fiber quality indices change range, we suggested that 5% changes of the major fiber quality indices（fiber length, fiber strength and micronaire） and 10% changes of fiber development components（cellulose, sucrose and callose） could be taken as criteria to judge whether fiber development and fiber quality have been significantly affected by high temperature stress. The key time window for cotton fiber development in response to the high temperature stress was 13–19 DPA, and the critical duration was about 5 days.
文摘In this study, we investigated the effect of sodium bicarbonate (NaHCO3) supplementation at a dose of 0.2 g·kg−1 40 min before an exercise on intermittent endurance performance and gastrointestinal distress. The participants were six healthy male students of a university. The Yo-Yo intermittent recovery test level 2 (Yo-Yo IR2) was used for the evaluation of intermittent endurance. The participants ingested water (Cont) or NaHCO3 independently at three timings. After drinking water, the Yo-Yo IR1 was performed for 2 min as warm-up. After resting for 5 min, the Yo-Yo IR2 was initiated. The measurement items were exercise distance, nutrition intake, biochemical test results, and blood gas analysis findings. The participants who ingested NaHCO3 had a 14% extended distance than those who ingested Cont, and 2/3 of those who took NaHCO3 showed a better motor performance. No significant difference was observed between the participants who took Cont and NaHCO3 in terms of pH level at baseline, and the NaHCO3 level was significantly higher during pre- and post-exercise (p 3 in terms of bicarbonate ion level at baseline, and the NaHCO3 level was significantly higher during pre- and post-exercise (p 3 at a low dose (0.2 g·kg−1), their exercise ability during an intermittent endurance test has improved. Furthermore, when digestive absorption is considered, eating a meal in advance may be able to suppress the onset of gastrointestinal distress.
文摘Fuel cell is a device that converts the chemical energy in the reactants into the electrical energy after steps of sequential electrochemical processes with no significant impact on the environment. For high altitude long endurance (HALE) of unmanned aircraft system (UAS) where fuel cell operates as a prime source of power, the operation and performance of a PEM fuel cell at different level of altitudes is vitally important. In this paper, the impact of direct using extracted air from high altitudes atmosphere in order to feed the stack is investigated, and the governing equations of the supplied air and oxygen to the PEM fuel cell stack are developed. The impact of high altitudes upon the operation and the consumption of air are determined in order to maintain certain level of delivered power to the load. Also the implications associated with operating the PEM fuel cell stack at high altitudes and different technical solutions are proposed. Various modes of Integral, Proportional-Integral, and Proportional-Integral-Derivative controller are introduced and examined for different time setting responses in order to determine the most adequate trade-off choice between fast response and reactants consumption which provides the necessary optimization of the air consumption for the developed model of PEM fuel cell used for UAS operation.
基金the financial support of National Key R&D Program of China (No.2017YFB1201100)
文摘Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive thermal management. In this paper, a multi-node transient thermal model for airborne electronic equipment is set up based on the thermal network method to predict their dynamic temperature responses under high altitude and long flight time conditions. Some relevant factors are considered into this temperature prediction model including flight environment,radiation, convection, heat conduction, etc. An experimental chamber simulating a high altitude flight environment was set up to survey the dynamic thermal responses of airborne electronic equipment in a UAV. According to the experimental measurement results, the multi-node transient thermal model is verified without consideration of the effects of flight speed. Then, a modified way about outside flight speed is added into the model to improve the temperature prediction performance. Finally, the corresponding simulation code is developed based on the proposed model. It can realize the dynamic temperature prediction of airborne electronic equipment under HALE conditions.
文摘To study the high-fat-diet induced rat obesity and the of fect of endurance training on the body fat content of obese rats, we randomly divided 66 male weanling SD rats into control(16 rats) and high fat diet group(50 rats). After 10 weeks, we chose diet-induced obese rats(DIO, 26 rats) and divided them into endurance training group(DIO-T, 8 rats) and DIO groups(DIO, 18 rats) randomly. Aner 8 weeks, endurance training, all rats were killed. The results showed that nosignificant difference was found between groups in body weight, the feed efficiency of DIO groups was higher than control groups, tke carass fat con tent of DIO-T group was significantlylower than DIO group, and plasma insulin concentration of DIO group was higher than control and DIO-T groups. It was suggested that rats’ obesity was induced obesity by high fat diet, dietary obesity had relation to higher eding efficiency and hyperinsulinemia. Endurance training can effectively reduce the body fat content of high-fat-diet induced obese rats by improving its hyper-insulinemia. Plasma TCH and TG of all rats had no significant difference.
