Force–Velocity–Power Profile in High-Elite Boulder, Lead, and Speed Climber Competitors

2020 ◽  
Vol 15 (7) ◽  
pp. 1012-1018
Author(s):  
Guillaume Levernier ◽  
Pierre Samozino ◽  
Guillaume Laffaye
Keyword(s):  
External Force ◽  
Coefficient Of Variation ◽  
High Speed ◽  
Intraclass Correlation ◽  
Force Production ◽  
Maximal Velocity ◽  
Mean Power ◽  
Power Profile ◽  
Force Velocity ◽  
The Difference

Purpose: To compare the force-production capacities among boulderers, lead climbers, and speed climbers during a pull-up test using a force–velocity–power profile. Methods: In total, 24 high-elite climbers (11 boulderers, 8 lead climbers, and 5 speed climbers) did 2 pull-ups at different percentages of their body mass (0%, 30%, 45%, 60%, and 70%). Force–velocity–power profile analyses were performed with the use of an accelerometer for each load. The intraclass correlation and coefficients of variation were calculated. A 1-way analysis of variance was performed with a Tukey post hoc test to assess the difference between the groups. Results: Regarding force, the coefficient of variation ranged from 1.00% to 6.18% and the intraclass correlation ranged from .98 to .99. For velocity, the coefficient of variation ranged from 2.75% to 6.62% and the intraclass correlation ranged from .84 to .95. The linear regression slope showed R2 to be between .93 and .99, confirming the high quality of the linear relationship between velocity and the external force produced during a pull-up. Boulderers presented significantly higher (P < .05) maximal power (+22.30% and +26.29%), mean power for the pull-up at body weight (+23.49% and +25.35%), and theoretical maximal velocity at zero force (+23.92% and +21.53%) than lead and speed climbers and a more significant curve increase (+35.21% compared with lead climbers). Conclusions: The reliability of the method was shown to be high. Moreover, boulderers were able to develop an important external force and had the capacity to maintain high speed when force production increased.

Should We Base Training Prescription on the Force–Velocity Profile? Exploratory Study of Its Between-Day Reliability and Differences Between Methods

2020 ◽  
pp. 1-7
Author(s):  
Pedro L. Valenzuela ◽  
Guillermo Sánchez-Martínez ◽  
Elaia Torrontegi ◽  
Javier Vázquez-Carrión ◽  
Zigor Montalvo ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Reliability Coefficient ◽  
Power Coefficient ◽  
Squat Jump ◽  
Jump Test ◽  
Force Velocity ◽  
Constrained Conditions ◽  
Vertical Jumps ◽  
Good Agreement

Purpose: To analyze the differences in the force–velocity (F–v) profile assessed under unconstrained (ie, using free weights) and constrained (ie, on a Smith machine) vertical jumps, as well as to determine the between-day reliability. Methods: A total of 23 trained participants (18 [1] y) performed an incremental load squat jump test (with ∼35%, 45%, 60%, and 70% of the subjects’ body mass) on 2 different days using free weights and a Smith machine. Nine of these participants repeated the tests on 2 other days for an exploratory analysis of between-day reliability. F–v variables (ie, maximum theoretical force [F0], velocity [v0], and power, and the imbalance between the actual and the theoretically optimal F–v profile) were computed from jump height. Results: A poor agreement was observed between the F–v variables assessed under constrained and unconstrained conditions (intraclass correlation coefficient [ICC] < .50 for all). The height attained during each single jump performed under both constrained and unconstrained conditions showed an acceptable reliability (coefficient of variation < 10%, ICC > .70). The F–v variables computed under constrained conditions showed an overall good agreement (ICC = .75–.95 for all variables) and no significant differences between days (P > .05), but a high variability for v0, the imbalance between the actual and the theoretically optimal F–v profile, and maximal theoretical power (coefficient of variation = 17.0%–27.4%). No between-day differences were observed for any F–v variable assessed under unconstrained conditions (P > .05), but all of the variables presented a low between-day reliability (coefficient of variation > 10% and ICC < .70 for all). Conclusions: F–v variables differed meaningfully when obtained from constrained and unconstrained loaded jumps, and most importantly seemed to present a low between-day reliability.

scholarly journals The Coefficient of Variation of Step Time Can Overestimate Gait Abnormality: Test-Retest Reliability of Gait-Related Parameters Obtained with a Tri-Axial Accelerometer in Healthy Subjects

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 577 ◽  
Author(s):  
Shunrou Fujiwara ◽  
Shinpei Sato ◽  
Atsushi Sugawara ◽  
Yasumasa Nishikawa ◽  
Takahiro Koji ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Step Length ◽  
Gait Parameter ◽  
Data Set ◽  
Gait Abnormality ◽  
Significant Difference ◽  
Assessment Time ◽  
The Difference ◽  
Gait Abnormalities

The aim of this study was to investigate whether variation in gait-related parameters among healthy participants could help detect gait abnormalities. In total, 36 participants (21 men, 15 women; mean age, 35.7 ± 9.9 years) performed a 10-m walk six times while wearing a tri-axial accelerometer fixed at the L3 level. A second walk was performed ≥1 month after the first (mean interval, 49.6 ± 7.6 days). From each 10-m data set, the following nine gait-related parameters were automatically calculated: assessment time, number of steps, stride time, cadence, ground force reaction, step time, coefficient of variation (CV) of step time, velocity, and step length. Six repeated measurement values were averaged for each gait parameter. In addition, for each gait parameter, the difference between the first and second assessments was statistically examined, and the intraclass correlation coefficient (ICC) was calculated with the level of significance set at p < 0.05. Only the CV of step time showed a significant difference between the first and second assessments (p = 0.0188). The CV of step time also showed the lowest ICC, at <0.50 (0.425), among all parameters. Test–retest results of gait assessment using a tri-axial accelerometer showed sufficient reproducibility in terms of the clinical evaluation of all parameters except the CV of step time.

scholarly journals A nanometer difference in myofilament lattice spacing of two cockroach leg muscles explains their different functions

2019 ◽  
Author(s):  
Travis Carver Tune ◽  
Weikang Ma ◽  
Thomas C. Irving ◽  
Simon Sponberg
Keyword(s):  
Lattice Spacing ◽  
Force Production ◽  
X Ray Diffraction ◽  
State Behavior ◽  
Time Resolved ◽  
Packing Structure ◽  
Leg Muscles ◽  
Force Velocity ◽  
The Difference ◽  
Tension Curves

AbstractMuscle is highly organized across scales. Consequently, small changes in arrangement of myofilaments can influence macroscopic function. Two leg muscles of a cockroach, have identical innervation, mass, twitch responses, length-tension curves, and force-velocity relationships. However, during running, one muscle is dissipative, while the other produces significant positive mechanical work. Using time resolved x-ray diffraction in intact, contracting muscle, we simultaneously measured the myofilament lattice spacing, packing structure, and macroscopic force production of these muscle to test if nanoscale differences could account for this conundrum. While the packing patterns are the same, one muscle has 1 nm smaller lattice spacing at rest. Under isometric activation, the difference in lattice spacing disappeared explaining the two muscles’ identical steady state behavior. During periodic contractions, one muscle undergoes a 1 nm greater change in lattice spacing, which correlates with force. This is the first identified feature that can account for the muscles’ different functions.

scholarly journals RADIO-ULNAR PRONATION VS FOREARM EXTENSION: WHICH THE BEST TO REACH THE MAXIMAL BADMINTON RACKET VELOCITY?

2020 ◽  
Vol 20 (2) ◽  
pp. 99-107
Author(s):  
M Phomsoupha ◽  
J Jeuvrey ◽  
G Laffaye
Keyword(s):  
Angular Velocity ◽  
High Speed ◽  
Skill Level ◽  
Maximal Velocity ◽  
Elbow Extension ◽  
End Points ◽  
Head Velocity ◽  
The Difference ◽  
Common Components

Aim. Forearm extension and radio-ulnar pronation are two common components of the final movement during each badminton smash stroke. By coordinating the forearm to produce both extension and pronation at the same time, racket head velocity can be increased. Thus, this study examined maximal velocity and racket deflection during both movements in regard with skill level. Materials and methods. Twenty-two players (8 experts and 14 novices) participated in this study. Wrist, handle and racket head velocity were recorded using high speed cameras (Vicon V8i at a frequency of 250 Hz). Results. The racket head velocity with radio-ulnar pronation was 16 % higher than with forearm extension. This higher velocity resulted from an 8 % higher acceleration and a 70 % higher maximal angular velocity of the end points of the forearm segments during radio-ulnar pronation. In each movement, experts’ maximal velocity was higher than that of novices (p < .001).The maximal velocity of the racket for novices was obtained with elbow extension (20.9 ± 4.8 m/s), with a gain of 47 %, whereas for experts, it was obtained with radio-ulnar pronation (33.9 ± 5.8 m/s), with a gain of 53 %. Conclusion. The difference between the best velocities in both samples is 39 %, obtained respectively by radio-ulnar pronation for experts and an elbow extension for novices. Forearm extension and radio-ulnar pronation acceleration on the handle led to an increase in racket head velocity.

Impairment of Sprint Mechanical Properties in an Actual Soccer Match: A Pilot Study

2016 ◽  
Vol 11 (7) ◽  
pp. 893-898 ◽  
Author(s):  
Ryu Nagahara ◽  
Jean-Benoit Morin ◽  
Masaaki Koido
Keyword(s):  
Mechanical Properties ◽  
High Speed ◽  
Force Production ◽  
Maximal Velocity ◽  
Horizontal Force ◽  
Time Data ◽  
Long Distance ◽  
Soccer Match ◽  
Long Distance Running ◽  
Before And After

Purpose:To assess soccer-specific impairment of mechanical properties in accelerated sprinting and its relation with activity profiles during an actual match.Methods:Thirteen male field players completed 4 sprint measurements, wherein running speed was obtained using a laser distance-measurement system, before and after the 2 halves of 2 soccer matches. Macroscopic mechanical properties (theoretical maximal horizontal force [F0], maximal horizontal sprinting power [Pmax], and theoretical maximal sprinting velocity [V0]) during the 35-m sprint acceleration were calculated from speed–time data. Players’ activity profiles during the matches were collected using global positioning system units.Results:After the match, although F0 and Pmax did not significantly change, V0 was reduced (P = .038), and the magnitude of this reduction correlated with distance (positive) and number (negative) of high-speed running, number of running (negative), and other low-intensity activity distance (negative) during the match. Moreover, Pmax decreased immediately before the second half (P = .014).Conclusions:The results suggest that soccer-specific fatigue probably impairs players’ maximal velocity capabilities more than their maximal horizontal force-production abilities at initial acceleration. Furthermore, long-distance running, especially at high speed, during the match may induce relatively large impairment of maximal velocity capabilities. In addition, the capability of producing maximal horizontal power during sprinting is presumably impaired during halftime of a soccer match with passive recovery. These findings could be useful for players and coaches aiming to train effectively to maintain sprinting performance throughout a soccer match when planning a training program.

Reliability and Sensitivity of Reaction Time Measurements During Quasi-Realistic Soccer Situations

Motor Control ◽  
2021 ◽  
pp. 1-11
Author(s):  
Lazar Tomic ◽  
Danica Janicijevic ◽  
Aleksandar Nedeljkovic ◽  
Bojan Leontijevic ◽  
Amador García-Ramos
Keyword(s):  
Reaction Time ◽  
Coefficient Of Variation ◽  
Size Range ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Stimulus Presentation ◽  
Soccer Players ◽  
Force Development ◽  
Professional Soccer ◽  
The Difference

Reliability and sensitivity of reaction time (RT) during quasi-realistic soccer situations was explored in 10 professional soccer players (skilled; age = 20.9 ± 3.6 years) and 10 males without soccer experience (nonskilled; age = 23.4 ± 0.5 years). The participants were instructed to react as fast as possible to a stimulus presented via the video-based method while standing on force platforms. RT was computed as the difference between the instant when the rate of force development of any leg reaches 5% of its maximal value and the instant of stimulus presentation. The results revealed acceptable to high reliability of RT (intraclass correlation coefficient median = .90; coefficient of variation ≤ 5.83%), and shorter RT for skilled compared with nonskilled participants in three out of eight comparisons (effect size range = 1.00–1.41). The video-based methods can be confidently used to assess the RT in soccer players.

scholarly journals Truncated Estimation of Skating Force-Velocity Profiling When Using High-Speed Video-Based Methods Compared to Radar-Derived Processing

2021 ◽  
Vol 9 ◽  
Author(s):  
Jerome Perez ◽  
Gaël Guilhem ◽  
Franck Brocherie
Keyword(s):  
High Speed ◽  
Ice Hockey ◽  
Time Shift ◽  
Maximal Velocity ◽  
High Speed Video ◽  
Lower Accuracy ◽  
Force Velocity ◽  
Linear Slope ◽  
Mean Differences ◽  
The Cost

This study aimed to compare the force-velocity mechanical variables derived from high-speed video- and radar-based method during forward skating sprint in ice hockey. Thirteen elite female ice hockey players performed two 40-m forward skating sprints to determine, in the horizontal plane, maximal velocity reached (Vmax), relative maximal theoretical force (F0), maximal theoretical velocity (V0), relative maximal power (Pmax), linear slope of the force-velocity relationship (FV slope), maximal value of the ratio of force (RFmax) and index of force application technique (Drf). Two different high-speed video-based methods adding a time shift (ST-TS) or not (ST) were used and independently compared to the radar-derived method. ST and ST-TS showed significant mean differences (all p &lt; 0.002) compared to radar-derived processing for all variables except for V0 (p = 0.26) and Vmax (p = 0.13) inferred from ST. In reference to radar-derived variables, ST-TS significantly induced larger lower values compared to radar of the main forward skating sprint determinants (Pmax, F0, RFmax and Drf) and moderate-to-large overestimation for velocity variables (V0 and Vmax). Correlations between ST or ST-TS and radar-derived methods ranged from trivial for velocity variables to very large for force and power variables. Consequently, practitioners must be aware that using such high-speed video-based methods would permit to determine mechanical variables at the cost of much lower accuracy and reliability than the radar-derived method.

Maintenance of Velocity and Power With Cluster Sets During High-Volume Back Squats

2016 ◽  
Vol 11 (7) ◽  
pp. 885-892 ◽  
Author(s):  
James J. Tufano ◽  
Jenny A. Conlon ◽  
Sophia Nimphius ◽  
Lee E. Brown ◽  
Laurent B. Seitz ◽  
...  
Keyword(s):  
Peak Power ◽  
Peak Velocity ◽  
High Volume ◽  
Effect Sizes ◽  
Maximal Velocity ◽  
Mean Power ◽  
Mean Velocity ◽  
Cluster Set ◽  
Cluster Sets ◽  
Force Velocity

Purpose:To compare the effects of a traditional set structure and 2 cluster set structures on force, velocity, and power during back squats in strength-trained men.Methods:Twelve men (25.8 ± 5.1 y, 1.74 ± 0.07 m, 79.3 ± 8.2 kg) performed 3 sets of 12 repetitions at 60% of 1-repetition maximum using 3 different set structures: traditional sets (TS), cluster sets of 4 (CS4), and cluster sets of 2 (CS2).Results:When averaged across all repetitions, peak velocity (PV), mean velocity (MV), peak power (PP), and mean power (MP) were greater in CS2 and CS4 than in TS (P < .01), with CS2 also resulting in greater values than CS4 (P < .02). When examining individual sets within each set structure, PV, MV, PP, and MP decreased during the course of TS (effect sizes 0.28–0.99), whereas no decreases were noted during CS2 (effect sizes 0.00–0.13) or CS4 (effect sizes 0.00–0.29).Conclusions:These results demonstrate that CS structures maintain velocity and power, whereas TS structures do not. Furthermore, increasing the frequency of intraset rest intervals in CS structures maximizes this effect and should be used if maximal velocity is to be maintained during training.

Temperature and force-velocity relationship of human muscles

1977 ◽  
Vol 42 (4) ◽  
pp. 471-475 ◽  
Author(s):  
R. A. Binkhorst ◽  
L. Hoofd ◽  
A. C. Vissers
Keyword(s):  
Temperature Effect ◽  
Coefficient Of Variation ◽  
Repeated Measurements ◽  
Muscle Temperature ◽  
Maximal Velocity ◽  
Maximal Power ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Human Muscles ◽  
Relationship Of

The force-velocity relationship of maximal contractions with the handgrip muscles is established in a group of subjects. The effect of different muscle temperatures is studied. The parameters vo (maximal velocity), Fo (maximal force), Pmax (maximal power), a/Fo and H (both parameters describing the shape of the curve), and Ft/Fo (the value of the force at which power is maximal) are established. It is shown that 1) in repeated measurements the coefficient of variation in general is less than 10% for all the parameters except a/Fo; 2) the parameter a/Fo should be discarded in comparative measurements since it is not linearly related to the course of the curve. A parameter called H should be used instead to describe the curvature; 3) an increase in muscle temperature is accompanied by an increase in magnitude of all parameters except Fo. The temperature effect expressed as Q10 in the range 22–38 degrees C is in the order of 1.2.

scholarly journals Normalization of Early Isometric Force Production as a Percentage of Peak Force During Multijoint Isometric Assessment

2020 ◽  
Vol 15 (4) ◽  
pp. 478-482
Author(s):  
Paul Comfort ◽  
Thomas Dos’Santos ◽  
Paul A. Jones ◽  
John J. McMahon ◽  
Timothy J. Suchomel ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Intraclass Correlation ◽  
Force Production ◽  
Correlation Coefficients ◽  
Collegiate Athletes ◽  
Peak Force ◽  
Specific Force ◽  
Intraclass Correlation Coefficients ◽  
Time Specific ◽  
Very High

Purpose: To determine the reliability of early force production (50, 100, 150, 200, and 250 ms) relative to peak force (PF) during an isometric mid-thigh pull and to assess the relationships between these variables. Methods: Male collegiate athletes (N = 29; age 21.1 [2.9] y, height 1.71 [0.07] m, body mass 71.3 [13.6] kg) performed isometric mid-thigh pulls during 2 separate testing sessions. Net PF and net force produced at each epoch were calculated. Within- and between-session reliabilities were determined using intraclass correlation coefficients and coefficient of variation percentages. In addition, Pearson correlation coefficients and coefficient of determination were calculated to examine the relationships between PF and time-specific force production. Results: Net PF and time-specific force demonstrated very high to almost perfect reliability both within and between sessions (intraclass correlation coefficients .82–.97; coefficient of variation percentages 0.35%–1.23%). Similarly, time-specific force expressed as a percentage of PF demonstrated very high to almost perfect reliability both within and between sessions (intraclass correlation coefficients .76–.86; coefficient of variation percentages 0.32%–2.51%). Strong to nearly perfect relationships (r = .615–.881) exist between net PF and time-specific net force, with relationships improving over longer epochs. Conclusion: Based on the smallest detectable difference, a change in force at 50 milliseconds expressed relative to PF > 10% and early force production (100, 150, 200, and 250 ms) expressed relative to PF of >2% should be considered meaningful. Expressing early force production as a percentage of PF is reliable and may provide greater insight into the adaptations to the previous training phase than PF alone.

Sign in / Sign up

Export Citation Format

Share Document