The Karvonen formula, which is widely used to estimate exercise intensity, contains maximum heart rate, H Rmax, as a variable. This study employed pedaling experiments to assess which of the proposed formulas for calc...The Karvonen formula, which is widely used to estimate exercise intensity, contains maximum heart rate, H Rmax, as a variable. This study employed pedaling experiments to assess which of the proposed formulas for calculating H Rmaxwas the most suitable for use with the Karvonen formula. First, two kinds of experiments involving an ergometer were performed: an all-in-one-day experiment that tested eight pedaling loads in one day, and a one-load-per-day experiment that tested one load per day for eight days.A comparison of the data on 7 subjects showed that the all-in-one-day type of experiment was better for assessing H Rmaxformulas,at least for the load levels tested in our experiments. A statistical analysis of the experimental data on 47 subjects showed two of the H Rmaxformulas to be suitable for use in the Karvonen formula to estimate exercise intensity for males in their 20 s. In addition, the physical characteristics of a person having the greatest impact on exercise intensity were determined.展开更多
Background:One-legged pedaling is of interest to elite cyclists and clinicians.However,muscular usage in 1-legged vs.2-legged pedaling is not fully understood.Thus,the study was aimed to examine changes in leg muscle ...Background:One-legged pedaling is of interest to elite cyclists and clinicians.However,muscular usage in 1-legged vs.2-legged pedaling is not fully understood.Thus,the study was aimed to examine changes in leg muscle activation patterns between 2-legged and 1-legged pedaling.Methods:Fifteen healthy young recreational cyclists performed both 1-legged and 2-legged pedaling trials at about 30 Watt per leg.Surface electromyography electrodes were placed on 10 major muscles of the left leg.Linear envelope electromyography data were integrated to quantify muscle activities for each crank cycle quadrant to evaluate muscle activation changes.Results:Overall,the prescribed constant power requirements led to reduced downstroke crank torque and extension-related muscle activities(vastus lateralis,vastus medialis,and soleus)in 1-legged pedaling.Flexion-related muscle activities(biceps femoris long head,semitendinosus,lateral gastrocnemius,medial gastrocnemius,tensor fasciae latae,and tibialis anterior)in the upstroke phase increased to compensate for the absence of contralateral leg crank torque.During the upstroke,simultaneous increases were seen in the hamstrings and uni-articular knee extensors,and in the ankle plantarflexors and dorsiflexors.At the top of the crank cycle,greater hip flexor activity stabilized the pelvis.Conclusion:The observed changes in muscle activities are due to a variety of changes in mechanical aspects of the pedaling motion when pedaling with only 1 leg,including altered crank torque patterns without the contralateral leg,reduced pelvis stability,and increased knee and ankle stiffness during the upstroke.展开更多
采用文献资料法,在PubMed、Web of Science、Scopus、Taylor&Francis数据库中对相关研究进行检索,主要汇总、分析有关骑行中肌肉激活和协同的研究文献。结果发现:肌肉的募集模式和协同激活影响到全身的代谢功率、曲柄上的输出功率...采用文献资料法,在PubMed、Web of Science、Scopus、Taylor&Francis数据库中对相关研究进行检索,主要汇总、分析有关骑行中肌肉激活和协同的研究文献。结果发现:肌肉的募集模式和协同激活影响到全身的代谢功率、曲柄上的输出功率以及骑行的总效率;下肢肌肉的激活在蹬踏过程中普遍存在双边不对称现象;一个完整蹬踏周期内不同阶段的下肢肌肉激活水平有差异,曲柄角度、地形、姿势、蹬踏频率也会对肌肉的募集产生影响;膝关节疼痛、肩颈酸痛、腰背疼痛等与肌肉异常工作有关的非创伤性损伤在骑行者身上频发。后续的研究可以着力于探究通过调整设置更匹配个体参数自的行车设定去改善非创伤性损伤中肌肉因素。展开更多
Purpose: The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake(%VO_(2max)), percentage of maximal heart rate(%HR_(ma...Purpose: The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake(%VO_(2max)), percentage of maximal heart rate(%HR_(max)), %VO_2 reserve(%VO_2R), and %HR reserve(%HRR)) in order to obtain the more appropriate method for exercise intensity prescription when using an immersible ergocycle(IE) and to propose a prediction equation to estimate oxygen consumption(VO_2) based on IE pedaling rate(rpm) for an individualized exercise training prescription.Methods: Thirty-three healthy participants performed incremental exercise tests on IE and dryland ergocycle(DE) at equal external power output(Pext). Exercise on IE began at 40 rpm and was increased by 10 rpm until exhaustion. Exercise on DE began with an initial load of 25 W and increased by 25 W/min until exhaustion. VO_2 was measured with a portable gas analyzer(COSMED K4b^2) during both incremental tests. On IE and DE, %VO_2R, %HRmax, and %HRR at equal Pext did not differ(p > 0.05).Results: The %HRR vs. %VO_2R regression for both IE and DE did not differ from the identity line %VO_2R IE = 0.99 × HRR IE(%) + 0.01(r^2= 0.91, SEE = 11%); %VO_2R DE = 0.94 × HRR DE(%) + 0.01(r^2= 0.94, SEE = 8%). Similar mean values for %HRmax, %VO_2R, and %HRR at equal Pext were observed on IE and DE. Predicted VO_2 obtained according to rpm on IE is represented by: VO_2(L/min) = 0.000542 × rpm2-0.026 × rpm + 0.739(r = 0.91, SEE = 0.319 L/min).Conclusion: The %HRR–%VO_2R relationship appears to be the most accurate for exercise training prescription on IE. This study offers new tools to better prescribe, control, and individualize exercise intensity on IE.展开更多
Once I found a pink moth on our front porch. I was per-haps eight years old, and it happened as I stepped out throughmy front door into the glass-enclosed vestibule, nearly like agreenhouse, where we left our boots in...Once I found a pink moth on our front porch. I was per-haps eight years old, and it happened as I stepped out throughmy front door into the glass-enclosed vestibule, nearly like agreenhouse, where we left our boots in the winter. A mothwas desperately trying to find its way off the porch. Several times I had found a bee or a moth trapped on展开更多
Yuan Jianglei has an amazing story to tell. The 27 year old is one of a handful of people who can say they have cycled through Africa - solo.Yuan began his epic adventure in the West African country of Benin, ending 1...Yuan Jianglei has an amazing story to tell. The 27 year old is one of a handful of people who can say they have cycled through Africa - solo.Yuan began his epic adventure in the West African country of Benin, ending 10,544 km and 333 days later in his hometown of Ningbo, east China＇s Zhejiang Province.展开更多
Yuan Jianglei,27,is one of a handful of people who can say they have cycled through Africa completely solo.Beginning his epic adventure in the West African country of Benin,Yuan finished 10,544 km and 333 days later i...Yuan Jianglei,27,is one of a handful of people who can say they have cycled through Africa completely solo.Beginning his epic adventure in the West African country of Benin,Yuan finished 10,544 km and 333 days later in his hometown of Ningbo, east China＇s Zhejiang Province. The journey, which came to a celebratory end in September 2017, took him through 16 countries.展开更多
The 'Bicycle Kingdom' seeks to be among medal nations in cycling events at the 2008 Olympic Games Although China has the largest number of people riding bicycles in the world, most Chinese ride to commute out ...The 'Bicycle Kingdom' seeks to be among medal nations in cycling events at the 2008 Olympic Games Although China has the largest number of people riding bicycles in the world, most Chinese ride to commute out of necessity and not really for sports, said Chen Jianmin, Head Coach of Hunan Cycling Club.展开更多
基金supported by Health Science Center Foundation,Japan
文摘The Karvonen formula, which is widely used to estimate exercise intensity, contains maximum heart rate, H Rmax, as a variable. This study employed pedaling experiments to assess which of the proposed formulas for calculating H Rmaxwas the most suitable for use with the Karvonen formula. First, two kinds of experiments involving an ergometer were performed: an all-in-one-day experiment that tested eight pedaling loads in one day, and a one-load-per-day experiment that tested one load per day for eight days.A comparison of the data on 7 subjects showed that the all-in-one-day type of experiment was better for assessing H Rmaxformulas,at least for the load levels tested in our experiments. A statistical analysis of the experimental data on 47 subjects showed two of the H Rmaxformulas to be suitable for use in the Karvonen formula to estimate exercise intensity for males in their 20 s. In addition, the physical characteristics of a person having the greatest impact on exercise intensity were determined.
基金supported by the University of Massachusetts Amherst(SP:Graduate School Fellowship,and School of Public Health and Health Sciences Dean’s PhD Summer FellowshipGEC:Faculty Research Grant).
文摘Background:One-legged pedaling is of interest to elite cyclists and clinicians.However,muscular usage in 1-legged vs.2-legged pedaling is not fully understood.Thus,the study was aimed to examine changes in leg muscle activation patterns between 2-legged and 1-legged pedaling.Methods:Fifteen healthy young recreational cyclists performed both 1-legged and 2-legged pedaling trials at about 30 Watt per leg.Surface electromyography electrodes were placed on 10 major muscles of the left leg.Linear envelope electromyography data were integrated to quantify muscle activities for each crank cycle quadrant to evaluate muscle activation changes.Results:Overall,the prescribed constant power requirements led to reduced downstroke crank torque and extension-related muscle activities(vastus lateralis,vastus medialis,and soleus)in 1-legged pedaling.Flexion-related muscle activities(biceps femoris long head,semitendinosus,lateral gastrocnemius,medial gastrocnemius,tensor fasciae latae,and tibialis anterior)in the upstroke phase increased to compensate for the absence of contralateral leg crank torque.During the upstroke,simultaneous increases were seen in the hamstrings and uni-articular knee extensors,and in the ankle plantarflexors and dorsiflexors.At the top of the crank cycle,greater hip flexor activity stabilized the pelvis.Conclusion:The observed changes in muscle activities are due to a variety of changes in mechanical aspects of the pedaling motion when pedaling with only 1 leg,including altered crank torque patterns without the contralateral leg,reduced pelvis stability,and increased knee and ankle stiffness during the upstroke.
文摘采用文献资料法,在PubMed、Web of Science、Scopus、Taylor&Francis数据库中对相关研究进行检索,主要汇总、分析有关骑行中肌肉激活和协同的研究文献。结果发现:肌肉的募集模式和协同激活影响到全身的代谢功率、曲柄上的输出功率以及骑行的总效率;下肢肌肉的激活在蹬踏过程中普遍存在双边不对称现象;一个完整蹬踏周期内不同阶段的下肢肌肉激活水平有差异,曲柄角度、地形、姿势、蹬踏频率也会对肌肉的募集产生影响;膝关节疼痛、肩颈酸痛、腰背疼痛等与肌肉异常工作有关的非创伤性损伤在骑行者身上频发。后续的研究可以着力于探究通过调整设置更匹配个体参数自的行车设定去改善非创伤性损伤中肌肉因素。
基金provided by the éPIC Foundation and the Montreal Heart Institute Foundation
文摘Purpose: The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake(%VO_(2max)), percentage of maximal heart rate(%HR_(max)), %VO_2 reserve(%VO_2R), and %HR reserve(%HRR)) in order to obtain the more appropriate method for exercise intensity prescription when using an immersible ergocycle(IE) and to propose a prediction equation to estimate oxygen consumption(VO_2) based on IE pedaling rate(rpm) for an individualized exercise training prescription.Methods: Thirty-three healthy participants performed incremental exercise tests on IE and dryland ergocycle(DE) at equal external power output(Pext). Exercise on IE began at 40 rpm and was increased by 10 rpm until exhaustion. Exercise on DE began with an initial load of 25 W and increased by 25 W/min until exhaustion. VO_2 was measured with a portable gas analyzer(COSMED K4b^2) during both incremental tests. On IE and DE, %VO_2R, %HRmax, and %HRR at equal Pext did not differ(p > 0.05).Results: The %HRR vs. %VO_2R regression for both IE and DE did not differ from the identity line %VO_2R IE = 0.99 × HRR IE(%) + 0.01(r^2= 0.91, SEE = 11%); %VO_2R DE = 0.94 × HRR DE(%) + 0.01(r^2= 0.94, SEE = 8%). Similar mean values for %HRmax, %VO_2R, and %HRR at equal Pext were observed on IE and DE. Predicted VO_2 obtained according to rpm on IE is represented by: VO_2(L/min) = 0.000542 × rpm2-0.026 × rpm + 0.739(r = 0.91, SEE = 0.319 L/min).Conclusion: The %HRR–%VO_2R relationship appears to be the most accurate for exercise training prescription on IE. This study offers new tools to better prescribe, control, and individualize exercise intensity on IE.
文摘Once I found a pink moth on our front porch. I was per-haps eight years old, and it happened as I stepped out throughmy front door into the glass-enclosed vestibule, nearly like agreenhouse, where we left our boots in the winter. A mothwas desperately trying to find its way off the porch. Several times I had found a bee or a moth trapped on
文摘Yuan Jianglei has an amazing story to tell. The 27 year old is one of a handful of people who can say they have cycled through Africa - solo.Yuan began his epic adventure in the West African country of Benin, ending 10,544 km and 333 days later in his hometown of Ningbo, east China＇s Zhejiang Province.
文摘Yuan Jianglei,27,is one of a handful of people who can say they have cycled through Africa completely solo.Beginning his epic adventure in the West African country of Benin,Yuan finished 10,544 km and 333 days later in his hometown of Ningbo, east China＇s Zhejiang Province. The journey, which came to a celebratory end in September 2017, took him through 16 countries.
文摘The 'Bicycle Kingdom' seeks to be among medal nations in cycling events at the 2008 Olympic Games Although China has the largest number of people riding bicycles in the world, most Chinese ride to commute out of necessity and not really for sports, said Chen Jianmin, Head Coach of Hunan Cycling Club.
