Rose chafer beetles(Protetia cuprea)are pollinators as well as agricultural pests,flying between flowers and trees while foraging for pollen and fruits.Calculating the energy they expend on flying during foraging acti...Rose chafer beetles(Protetia cuprea)are pollinators as well as agricultural pests,flying between flowers and trees while foraging for pollen and fruits.Calculating the energy they expend on flying during foraging activity faces the challenge of measuring the metabolic rate(MR)of free-flying insects in an open space.We overcame this challenge by using the bolus injection of ^(13)C Na-bicarbonate technique to measure their metabolic energy expenditure while flying in a large flight arena.Concurrently,we tracked the insects with high-speed cameras to extract their flight trajectory,from which we calculated the mechanical power invested in flying for each flight bout.We found that the chemical(metabolic)energy input converted to mechanical flight energy output at a mean efficiency of 10.4%±5.2%,with a trend of increased efficiency in larger conspecifics(efficiency scaled with body mass to the power of 1.4).The transition in the summer from a diet of pollen to that of fruits may affect the energy budget available for foraging.Starved P.cuprea,feeding on apples ad libitum,increased their body mass by an average of 6%in 2 h.According to our calculations,such a meal can power a 630-m flight(assuming a carbohydrate assimilation efficiency of 90%).Pollen,with a low water and carbohydrate content but rich in proteins and lipids,has a higher caloric content and should assimilate differently when converting food to flight fuel.The high cost of aerial locomotion is inherent to the foraging behavior of rose chafers,explaining their short flight bouts followed by prolonged feeding activity.展开更多
Background： Smokeless tobacco is widely used by athletes to enhance performance. Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems, involving tissue blood flow and cir...Background： Smokeless tobacco is widely used by athletes to enhance performance. Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems, involving tissue blood flow and circulatory vasoreactivity. The aim of this study was to investigate the effects of the oral smokeless tobacco （Swedish snus （SS）） on the perception of fatigue and time to exhaustion （TTE） during moderate-intensity aerobic exercise. Methods： Fourteen healthy non-tobacco male users were recruited for a double-blind, controlled crossover design （SS vs. snus placebo （SP））. Subjects were tested for 3 sessions： experimental session 1 （Exp 1） consisted of an incremental test to determine the maximal aerobic power out-put （Wmax）, whereas Exp2 and Exp3 consisted of exercising at 65%Wmax until exhaustion in SS or SP conditions. During Exp2 and Exp3, muscle and cerebral oxygenation was assessed by means of near-infrared spectroscopy, and the rating of perceived exertion （RPE） was recorded. Results： Comparing SS with SP tests, significant differences （p 〈 0.05） were found in the values of cerebral （-3%） and muscular tissues oxygenation （-4%） in the first 30 min of exercise. The RPE values were not significantly different between the 2 conditions （SS vs. SP）. No significant difference was found in TTE （SS： 54.25 ± 21.84 min; SP： 50.01 ± 17.03 min）. Conclusion： This study showed that muscular and cerebral oxygenation increased significantly with snus administration during an endurance exercise until exhaustion, but this did not affect fatigue perception and TTE. The results showed that snus could not be considered an ergogenic substance in non-tobacco users.2018 Published by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license. （http：//creativecommons.org/licenses/by-nc-nd/4.0/）.展开更多
Purpose The aim of this study was to determine the modulatory roles of biological maturity and age on the predictors of performance in youth swimmers and their stability over a six-month training cycle.Methods In tota...Purpose The aim of this study was to determine the modulatory roles of biological maturity and age on the predictors of performance in youth swimmers and their stability over a six-month training cycle.Methods In total,28 swimmers(10 pre-pubertal[6 boys],11.1±1.8 years;18 pubertal[8 boys],15.2±2.0 years old)and 26 untrained controls(15 pre-pubertal[10 boys],9.7±1.5 years;11 pubertal[6 boys],14.4±0.5 years old)were recruited.At baseline,3-and 6-months,participants completed an incremental ramp cycle test,isometric handgrip strength test and countermovement jumps,with speed assessed as a measure of performance in swimmers.Principle component analysis(PCA)identified factors that described youth swimmers’physical profile,with linear mixed models subsequently used to determine their interaction with age and maturity on performance.Results Aerobic fitness and upper body strength were significantly higher in the trained participants,irrespective of maturity status or time-point.Four key factors were identified through PCA(anthropometrics;strength;aerobic capacity;aerobic rate),accounting for 90%of the between parameter variance.Age exerted a widespread influence on swimming performance predic-tors,influencing all four factors,whilst maturity only influenced the aerobic factors.The key age of divergence was 13 years.Conclusion Overall,the present study found no evidence of a maturational threshold in the aerobic or strength-related response to training in youth.The influence of age on performance predictors suggests that utilising a single or select group of parameters to inform selection and/or talent identification throughout the dynamic processes of growth and maturation should be avoided.展开更多
文摘Rose chafer beetles(Protetia cuprea)are pollinators as well as agricultural pests,flying between flowers and trees while foraging for pollen and fruits.Calculating the energy they expend on flying during foraging activity faces the challenge of measuring the metabolic rate(MR)of free-flying insects in an open space.We overcame this challenge by using the bolus injection of ^(13)C Na-bicarbonate technique to measure their metabolic energy expenditure while flying in a large flight arena.Concurrently,we tracked the insects with high-speed cameras to extract their flight trajectory,from which we calculated the mechanical power invested in flying for each flight bout.We found that the chemical(metabolic)energy input converted to mechanical flight energy output at a mean efficiency of 10.4%±5.2%,with a trend of increased efficiency in larger conspecifics(efficiency scaled with body mass to the power of 1.4).The transition in the summer from a diet of pollen to that of fruits may affect the energy budget available for foraging.Starved P.cuprea,feeding on apples ad libitum,increased their body mass by an average of 6%in 2 h.According to our calculations,such a meal can power a 630-m flight(assuming a carbohydrate assimilation efficiency of 90%).Pollen,with a low water and carbohydrate content but rich in proteins and lipids,has a higher caloric content and should assimilate differently when converting food to flight fuel.The high cost of aerial locomotion is inherent to the foraging behavior of rose chafers,explaining their short flight bouts followed by prolonged feeding activity.
基金supported by research funds allocated to the following departments at the University of Verona:Neurosciences,Biomedicine and Movement Sciences,and Diagnostic and Public Health
文摘Background： Smokeless tobacco is widely used by athletes to enhance performance. Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems, involving tissue blood flow and circulatory vasoreactivity. The aim of this study was to investigate the effects of the oral smokeless tobacco （Swedish snus （SS）） on the perception of fatigue and time to exhaustion （TTE） during moderate-intensity aerobic exercise. Methods： Fourteen healthy non-tobacco male users were recruited for a double-blind, controlled crossover design （SS vs. snus placebo （SP））. Subjects were tested for 3 sessions： experimental session 1 （Exp 1） consisted of an incremental test to determine the maximal aerobic power out-put （Wmax）, whereas Exp2 and Exp3 consisted of exercising at 65%Wmax until exhaustion in SS or SP conditions. During Exp2 and Exp3, muscle and cerebral oxygenation was assessed by means of near-infrared spectroscopy, and the rating of perceived exertion （RPE） was recorded. Results： Comparing SS with SP tests, significant differences （p 〈 0.05） were found in the values of cerebral （-3%） and muscular tissues oxygenation （-4%） in the first 30 min of exercise. The RPE values were not significantly different between the 2 conditions （SS vs. SP）. No significant difference was found in TTE （SS： 54.25 ± 21.84 min; SP： 50.01 ± 17.03 min）. Conclusion： This study showed that muscular and cerebral oxygenation increased significantly with snus administration during an endurance exercise until exhaustion, but this did not affect fatigue perception and TTE. The results showed that snus could not be considered an ergogenic substance in non-tobacco users.2018 Published by Elsevier B.V. on behalf of Shanghai University of Sport. This is an open access article under the CC BY-NC-ND license. （http：//creativecommons.org/licenses/by-nc-nd/4.0/）.
文摘Purpose The aim of this study was to determine the modulatory roles of biological maturity and age on the predictors of performance in youth swimmers and their stability over a six-month training cycle.Methods In total,28 swimmers(10 pre-pubertal[6 boys],11.1±1.8 years;18 pubertal[8 boys],15.2±2.0 years old)and 26 untrained controls(15 pre-pubertal[10 boys],9.7±1.5 years;11 pubertal[6 boys],14.4±0.5 years old)were recruited.At baseline,3-and 6-months,participants completed an incremental ramp cycle test,isometric handgrip strength test and countermovement jumps,with speed assessed as a measure of performance in swimmers.Principle component analysis(PCA)identified factors that described youth swimmers’physical profile,with linear mixed models subsequently used to determine their interaction with age and maturity on performance.Results Aerobic fitness and upper body strength were significantly higher in the trained participants,irrespective of maturity status or time-point.Four key factors were identified through PCA(anthropometrics;strength;aerobic capacity;aerobic rate),accounting for 90%of the between parameter variance.Age exerted a widespread influence on swimming performance predic-tors,influencing all four factors,whilst maturity only influenced the aerobic factors.The key age of divergence was 13 years.Conclusion Overall,the present study found no evidence of a maturational threshold in the aerobic or strength-related response to training in youth.The influence of age on performance predictors suggests that utilising a single or select group of parameters to inform selection and/or talent identification throughout the dynamic processes of growth and maturation should be avoided.
