DETERMINATION OF OPTIMAL RESISTANCE FOR LOWER BODY PEAK POWER

1999 ◽  
Vol 31 (Supplement) ◽  
pp. S79
Author(s):  
M. G. Collins ◽  
S. S. Kimple ◽  
D. G. Dolny ◽  
H. P. Davis
Keyword(s):  
Peak Power ◽  
Lower Body

Coordinated changes in contractility, energetics, and isomyosins after aortic stenosis

1987 ◽  
Vol 252 (2) ◽  
pp. H275-H282
Author(s):  
Y. Lecarpentier ◽  
L. B. Bugaisky ◽  
D. Chemla ◽  
J. J. Mercadier ◽  
K. Schwartz ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Peak Power ◽  
Ventricular Hypertrophy ◽  
Left Ventricular ◽  
Ascending Aorta ◽  
Peak Power Output ◽  
Shortening Velocity ◽  
Old Rats ◽  
Quantitative Changes

To investigate possible alterations of myocardial performance in young rats, cardiac hypertrophy was induced by stenosis of the ascending aorta (AS) in three groups of 25-day-old rats that were compared with three groups of sham-operated controls (C). The cardiac overload duration was 8-10 days, 1 mo, and 2 mo in groups 1, 2, and 3, respectively. Mechanics and energetics were studied in left ventricular papillary muscles, and determination of the V1 and V3 isomyosin pattern was achieved in the same papillary muscle. The majority of quantitative changes concerning the cardiac growth process, contractility, and isomyosin shifts occurred within 8-10 days of stenosis. At this point, the degree of left ventricular hypertrophy relative to C was 53 +/- 6%, whereas maximum unloaded shortening velocity (Vmax) decreased significantly (2.8 +/- 0.1 in C vs. 1.9 +/- 0.1 Lmax/s in AS), peak power output (Emax) decreased (1.8 +/- 0.3 in C vs. 0.6 +/- 0.1 in AS), and the curvature of Hill's hyperbola increased (1.3 +/- 0.4 in C vs. 2.0 +/- 0.7 in AS); moreover, the percent V1 isomyosin decreased significantly (98 +/- 1 in C vs. 51 +/- 3% in AS) and the percent V3 isomyosin increased significantly (2 +/- 1 in C vs. 26 +/- 2% in AS). Beyond 8-10 days of AS, additional changes in cardiac hypertrophy and in mechanical and biochemical parameters were less marked.(ABSTRACT TRUNCATED AT 250 WORDS)

Refractory Metal Facings for Protection of Metal Surfaces Subjected to Repeated High-Temperature Pulses

1959 ◽  
Vol 81 (2) ◽  
pp. 197-202
Author(s):  
Aaron Cohen ◽  
Edward Homer
Keyword(s):  
Refractory Metal ◽  
Peak Power ◽  
Direct Relationship ◽  
High Energy ◽  
Analytical Determination ◽  
High Peak Power ◽  
Resonant Structure ◽  
High Energy Electrons ◽  
The Impact

Because the operating frequency of a magnetron has a direct relationship to the size of the resonant structure, the power at a given frequency that can be obtained from a magnetron may be limited by the temperature which the resonating structure can withstand. A rise in the temperature of the resonant structure is caused by the impact of high-energy electrons emitted from the cathode at high peak-power levels for short durations. This paper deals with the analytical determination of the temperature of the resonant structure, a solution to the heat problem in which a thin coating of refractory metal is used to prevent the vulnerable components from melting, and some experimental results to verify the analysis.

Functional Lower-Body Power: A Comparison Study Between Physically Inactive, Recreationally Active, and Masters Athlete Late-Middle-Aged Adults

2016 ◽  
Vol 24 (4) ◽  
pp. 501-507 ◽  
Author(s):  
Jordan M. Glenn ◽  
Michelle Gray ◽  
Jennifer L. Vincenzo ◽  
Matthew S. Stone
Keyword(s):  
Peak Power ◽  
Average Power ◽  
Functional Fitness ◽  
Lower Body ◽  
Middle Aged ◽  
Active Lifestyle ◽  
Sit To Stand ◽  
Masters Athlete ◽  
Middle Aged Adults ◽  
Lower Body Power

Muscular power decreases with age, and lower-body power relates to overall functional fitness; however, functional lower-body power has not been evaluated in late-middle-aged (LMA) populations. Purpose:To evaluate average and peak lower-body functional power and velocity among sedentary (SED), recreationally active (RA), and masters athlete (MA) LMA adults.Methods:Participants were SED (n = 13, age = 59.3 ± 4.5 years), RA (n = 35, age = 59.6 ± 5.0 years), and MA (n = 26, age = 56.7 ± 5.4 years). Five sit-to-stand trials were completed to assess lower-body functional power. Average/peak power and velocity were calculated for each trial. Power was expressed relatively to account for participant body weight. Results:MA (13.44 ± 2.76 W/kg) had significantly (p < .01) greater peak power compared with SED (9.99 ± 2.70 W/ kg) and RA (9.93 ± 2.30 W/kg). Similar significant (p < .01) differences existed for peak velocity (SED = 1.02 ± 0.22 m/s, RA = 1.04 ± 0.22 m/s, MA = 1.25 ± 0.19 m/s). No differences existed for average power or velocity between groups.Conclusions:Maintaining a competitively active lifestyle results in greater lower-body functional power in LMA adults and may support longitudinal functionality.

scholarly journals Verification-phase tests show low reliability and add little value in determining V̇O2max in young trained adults

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245306
Author(s):  
Jonathan Wagner ◽  
Max Niemeyer ◽  
Denis Infanger ◽  
Timo Hinrichs ◽  
Clement Guerra ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
No Value ◽  
Cardiorespiratory Fitness ◽  
Peak Power ◽  
Diurnal Variations ◽  
Peak Power Output ◽  
Fitness Tests ◽  
Image Position ◽  
Additional Value

Objective This study compared the robustness of a V˙O2-plateau definition and a verification-phase protocol to day-to-day and diurnal variations in determining the true V˙O2max. Further, the additional value of a verification-phase was investigated. Methods Eighteen adults performed six cardiorespiratory fitness tests at six different times of the day (diurnal variation) as well as a seventh test at the same time the sixth test took place (day-to-day variation). A verification-phase was performed immediately after each test, with a stepwise increase in intensity to 50%, 70%, and 105% of the peak power output. Results Participants mean V˙O2peak was 56 ± 8 mL/kg/min. Gwet’s AC1 values (95% confidence intervals) for the day-to-day and diurnal variations were 0.64 (0.22, 1.00) and 0.71 (0.42, 0.99) for V˙O2-plateau and for the verification-phase 0.69 (0.31, 1.00) and 0.07 (−0.38, 0.52), respectively. In 66% of the tests, performing the verification-phase added no value, while, in 32% and 2%, it added uncertain value and certain value, respectively, in the determination of V˙O2max. Conclusion Compared to V˙O2-plateau the verification-phase shows lower reliability, increases costs and only adds certain value in 2% of cases.

scholarly journals Determination of Partial Photochemical Quantum Yields of Reversible Photoisomerizations of Stilbene-1 Derivatives

1985 ◽  
Vol 40 (4) ◽  
pp. 317-323
Author(s):  
G. Gauglitz ◽  
R. Goes ◽  
W. Stooß ◽  
R. Raue
Keyword(s):  
Reaction Time ◽  
Peak Power ◽  
Quantum Yields ◽  
Detailed Knowledge ◽  
Laser Dyes ◽  
Derivatives Of ◽  
Laser Activity

Partial photochemical quantum yields of derivatives of stilbene-1 can be determined by a new microprocessor controlled apparatus for the measurement of fluorescence intensities in dependence on reaction time. The consecutive photoproducts must not be known. Some of the 20 examined dyes show laser activity combined with relatively high photostability. Photochemical quantum yields and laser peak power were determined in dependence on structure. A detailed knowledge of the photokinetic parameters gives the opportunity to obtain indications of efficient and photostable laser dyes.

scholarly journals Assessing Lower-Body Peak Power in Elite Rugby-Union Players

2011 ◽  
Vol 25 (6) ◽  
pp. 1616-1621 ◽  
Author(s):  
Christos K Argus ◽  
Nicholas D Gill ◽  
Justin WL Keogh ◽  
Will G Hopkins
Keyword(s):  
Peak Power ◽  
Rugby Union ◽  
Lower Body

scholarly journals Which anthropometric and lower body power variables are predictive of professional and amateur playing status in male rugby union players?

2018 ◽  
Vol 14 (1) ◽  
pp. 82-90 ◽  
Author(s):  
Thomas W Jones ◽  
Karen Keane ◽  
Andrew Smith ◽  
Jack Dent ◽  
Kevin McShane ◽  
...  
Keyword(s):  
Physical Performance ◽  
Peak Power ◽  
Peak Velocity ◽  
Rugby Union ◽  
Peak Force ◽  
Lower Body ◽  
Anthropometric Measures ◽  
Standard Data ◽  
Time To Peak ◽  
Lower Body Power

The purpose of this study was to compare anthropometric and lower body power measurements between current professional and amateur male rugby union players. The present study also sought to determine which anthropometric and physical performance variables were predictive of playing standard. Thirty professional and 30 amateur RU players performed Wattbike 6 s maximal effort (WB6S) and countermovement (CMJ) and squat jump (SJ) assessments, anthropometric measures were also taken. Dependant variables recorded and analysed including: body mass, stature, Σ8 site skinfolds, WB6S absolute and relative peak power, CMJ and SJ average concentric force, jump height, peak velocity, time to peak force, rate of force development (RFD) and absolute and relative peak force and power. Professional players were heavier, taller and leaner than their amateur counterparts ( p < 0.05). Professional players performed significantly better in all physical performance measures except CMJ and SJ time to peak force, CMJ RFD and SJ relative peak force. Variables which were predictive of playing standard were: Σ8 skinfolds, CMJ peak velocity and WB6S absolute and relative peak power ( p < 0.05). These findings indicate that the current body of male professional RU players is anthropometrically and physically superior to their amateur counterparts, although not all variables assessed here were predictive of playing standard. Data presented here indicate that Σ8 skinfolds, WB6S absolute and relative power and CMJ peak velocity are predictive of playing standard, whereas other anthropometric and strength and power variables are not.

Similar maximal oxygen uptake assessment from a step cycling incremental test and verification tests on the same or different day

2020 ◽  
Vol 45 (4) ◽  
pp. 357-361 ◽  
Author(s):  
Leonardo Trevisol Possamai ◽  
Fernando de Souza Campos ◽  
Paulo Cesar do Nascimento Salvador ◽  
Rafael Alves de Aguiar ◽  
Luiz Guilherme Antonacci Guglielmo ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Power Output ◽  
Maximal Oxygen Uptake ◽  
Peak Power ◽  
Individual Variability ◽  
Peak Power Output ◽  
Time To Exhaustion ◽  
Incremental Test ◽  
Incremental Protocol

The present study aimed to compare maximal oxygen uptake of a step incremental test with time to exhaustion verification tests (TLIM) performed on the same or different day. Nineteen recreationally trained cyclists (age: 23 ± 2.7 years; maximal oxygen uptake: 48.0 ± 5.8 mL·kg−1·min−1) performed 3 maximal tests as follows: (i) same day: an incremental test with 3-min stages followed by a TLIM at 100% of peak power output of the incremental test (TLIM-SAME) interspaced by 15 min; and (ii) different day: a TLIM at 100% of peak power output of the incremental test (TLIM-DIFF). The maximal oxygen uptake was determined for the 3 tests. The maximal oxygen uptake was not different among the tests (incremental: 3.83 ± 0.41; TLIM-SAME: 3.72 ± 0.42; TLIM-DIFF: 3.75 ± 0.41 L·min−1; P = 0.951). Seven subjects presented a variability greater than ±3% in both verification tests compared with the incremental test. The same-day verification test decreased the exercise tolerance (240 ± 38 vs. 310 ± 36 s) compared with TLIM-DIFF (P < 0.05). In conclusion, the incremental protocol is capable of measuring maximal oxygen uptake because similar values were observed in comparison with verification tests. Although the need for the verification phase is questionable, the additional tests are useful to evaluate individual variability. Novelty Step incremental test is capable of measuring maximal oxygen uptake with similar values during TLIM on the same or different day. Although the necessity of the verification phase is questionable, it can allow the determination of variability in maximal oxygen uptake.

Diaphragm contractile dysfunction in MyoD gene-inactivated mice

2002 ◽  
Vol 283 (3) ◽  
pp. R583-R590 ◽  
Author(s):  
Jessica L. Staib ◽  
Steven J. Swoap ◽  
Scott K. Powers
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Contractile Properties ◽  
Peak Power Output ◽  
Force Frequency ◽  
Shortening Velocity ◽  
Frequency Relationship ◽  
Myod Gene

MyoD is one of four myogenic regulatory factors found exclusively in skeletal muscle. In an effort to better understand the role that MyoD plays in determining muscle contractile properties, we examined the effects of MyoD deletion on both diaphragmatic contractile properties and myosin heavy chain (MHC) phenotype. Regions of the costal diaphragm from wild-type and MyoD knockout [ MyoD (−/−)] adult male BALB/c mice ( n = 8/group) were removed, and in vitro diaphragmatic contractile properties were measured. Diaphragmatic contractile measurements revealed that MyoD (−/−) animals exhibited a significant ( P < 0.05) downward shift in the force-frequency relationship, a decrement in maximal specific tension (Po; −33%), a decline in maximal shortening velocity (Vmax; −37%), and concomitant decrease in peak power output (−47%). Determination of MHC isoforms in the diaphragm via gel electrophoresis revealed that MyoD elimination resulted in a fast-to-slow shift ( P < 0.05) in the MHC phenotype toward MHC types IIA and IIX in MyoD (−/−) animals. These data indicate that MyoD deletion results in a decrease in diaphragmatic submaximal force generation and Po, along with decrements in both Vmax and peak power output. Hence, MyoD plays an important role in determining diaphragmatic contractile properties.

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