scholarly journals Lack of Evidence for Non-Local Muscle Fatigue and Performance Enhancement in Young Adults

2021 ◽  
pp. 339-348
Author(s):  
Gerard M.J. Power ◽  
Emily Colwell ◽  
Atle Hole Saeterbakken ◽  
Eric J. Drinkwater ◽  
David G. Behm
Keyword(s):  
Contact Time ◽  
Performance Enhancement ◽  
Knee Extension ◽  
Muscle Performance ◽  
Knee Extensors ◽  
Small Magnitude ◽  
Post Test ◽  
Proxy Measure ◽  
Non Local ◽  
And Performance

Post-activation performance enhancement (PAPE) is an improvement to voluntary muscle performance following a conditioning activity. There is evidence of fatigue resistance deficits in non-exercised muscles following unilateral fatiguing exercise of a contralateral muscle. The purpose of this study was to determine if a unilateral conditioning exercise protocol could induce PAPE in a contralateral, non-exercised muscle in young healthy adults. Thirty-two recreationally trained (n = 16) and athletically trained (n = 16) participants (16 males; age: 22.9 ± 2.03 years; height: 1.81 ± 0.06 m; weight: 82.8 ± 9.43 kg, and 16 females; age: 23.1 ± 2.80 years; height: 1.67 ± 0.07 m; weight: 66.4 ± 11.09 kg) were randomly allocated into two groups (dominant or non-dominant limb intervention). The experimental intervention, involved a conditioning exercise (4-repetitions of 5-seconds knee extension maximal voluntary isometric contractions: MVIC) with either the dominant (DOM) (n = 16) or non-dominant (ND) (n = 16) knee extensors with testing of the same (exercised) or contralateral (non-exercised) leg as well as a control (no conditioning exercise: n = 32) condition. Testing was performed before, 1-minute and 10-minutes after a high intensity, low volume, conditioning protocol (2 sets of 2x5-s MVIC). Pre- and post-testing included MVIC force and F100 (force developed in the first 100 ms: a proxy measure of rate of force development) and unilateral drop jump (DJ) height and contact time. There were no significant MVIC peak force or EMG nor DJ height or contact time interactions (intervention x limb dominance x time). The pre-test (0.50 ± 0.13) dominant leg MVIC F100 forces exceeded (p = 0.02) both post-test and post-10 min by a small magnitude 8.7% (d = 0.31). There was also a significant (p = 0.02) time x intervention leg x testing leg intervention, although it was observed that the control condition was as likely to demonstrate small to large magnitude changes as were the dominant and non-dominant legs. Following the conditioning activity, there was no significant evidence for non-local improvements (PAPE), or performance decreases.

The Effects of Taping on Muscle Activity and Throwing Velocity in Fatigued Baseball Players

2021 ◽  
Vol 3 (1) ◽  
pp. 18-29
Author(s):  
Kara-Lyn R. Harrison ◽  
Paolo Sanzo ◽  
Carlos Zerpa ◽  
Taryn Klarner
Keyword(s):  
Pilot Study ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Performance Enhancement ◽  
Maximum Velocity ◽  
Baseball Players ◽  
Kinesio Tape ◽  
Significant Difference ◽  
Post Test ◽  
And Performance

Due to the repetitive high forces and torques placed on an individual during a baseball pitch, shoulder pain is present in 46-57% of pitchers. Therapeutic taping has been proposed to have beneficial qualities in injury prevention, rehabilitation, and performance enhancement via muscular facilitation. Therefore, the purpose of this pilot study was to investigate the effect of taping on the velocity of an overhead baseball throw and muscle activation patterning of the supraspinatus, infraspinatus, and pectoralis major muscles in baseball players after muscle fatigue was induced. Participants were asked to complete three pre-test maximum velocity overhead throws, a fatiguing protocol, followed by three post-test maximum velocity pitches. There was no statistically significant difference in throwing velocity or muscle activity with the application of the different taping conditions in the three phases of an overhead baseball throw. These finding suggest Kinesio Tape® does not change muscle activation or velocity of overhead baseball throws when compared to a no tape condition.

scholarly journals Investigation of Inter-Limb Symmetry in Knee Extensors Using Different Strength Outcome Measures

Diagnostics ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1882
Author(s):  
Darjan Smajla ◽  
Jure Žitnik ◽  
Nejc Šarabon
Keyword(s):  
Regression Line ◽  
Knee Extension ◽  
Cross Sectional Study ◽  
Voluntary Contraction ◽  
Muscle Performance ◽  
Knee Extensors ◽  
Strong Correlations ◽  
Cross Sectional ◽  
Isokinetic Torque ◽  
Leg Dominance

Muscle performance between contra-lateral knee extensors is most often assessed using maximal test for isometric/isokinetic torque evaluation. Recently, the rate of force development scaling factor (RFD-SF) has been used to evaluate neuromuscular capacity with a range of submaximal target peak torques, which could highlight other aspects of inter-limb (a)symmetry. The aim of our study was to investigate the differences, associations, and agreement between inter-limb symmetries of knee extensors using maximal torque (Tmax) rate of torque development (RTD), slope of the RFD-SF regression line (k), and theoretical peak of RTD (TPRTD). A total of 236 young, healthy athletes participated in the cross-sectional study. All participants performed unilateral knee extension (maximal voluntary contraction protocol and RFD-SF protocol) with both legs in the isometric knee dynamometer. Inter-limb symmetries were calculated for each outcome measure. Our results showed significant differences between all symmetry values (Tmax (91.7%), RTD (85.2%), k (94.2%), TPRTD (95.9%)). Significant strong correlations were found between symmetry values calculated from k and TPRTD (r = 0.88, p < 0.001), while weak correlation was found between Tmax and RTD (r = 0.17, p < 0.01. Fair agreement regarding leg dominance was found between Tmax and RTD values. Our results suggest that inter-limb (a)symmetries are metric- and task-specific.

A Measure of Motor Control at the Knee in Cerebral Palsy

2001 ◽  
Vol 17 (4) ◽  
pp. 335-343 ◽  
Author(s):  
Jack R. Engsberg ◽  
Joanne M. Wagner ◽  
Angela K. Reitenbach ◽  
Kevin W. Hollander ◽  
John W. Standeven
Keyword(s):  
Cerebral Palsy ◽  
Motor Control ◽  
Standard Deviation ◽  
Knee Extension ◽  
Knee Extensors ◽  
Median Frequency ◽  
Time Data ◽  
Average Standard Deviation ◽  
Small Magnitude ◽  
Target Force

This investigation developed a measure of motor control for the knee extensors in adults with cerebral palsy (CP). Four adults with CP and 4 able-bodied (AB) adults participated. A KinCom dynamometer rotated the knee from approximately 90º of knee flexion to 10º/s less than the participant’s maximum knee extension at a speed of 10º/s, while the participant attempted to match a 44.5-N “target” force. The average, standard deviation, and median frequency of the force-time data were used to describe the test results. The individual force values for the AB group were near the target force and clustered together. The values for the CP group were also near the target force, but displayed greater variation. The average standard deviation for the CP group was more than three times larger than that of the AB group. The average median frequency for the CP group was less than that of the AB group. Results pointed to differing strategies for each group as they attempted to match the target force. The AB group attempted to match the target force with frequent small-magnitude force changes, while the CP group attempted to match the target force with fewer oscillations of greater magnitude. The methods employed in the present investigation are initial attempts to quantify one aspect of motor control, a visually guided tracking task.

scholarly journals Effects of Vibration Exercise on Muscle Performance and Mobility in an Older Population

2007 ◽  
Vol 15 (4) ◽  
pp. 367-381 ◽  
Author(s):  
Sven Rees ◽  
Aron Murphy ◽  
Mark Watsford
Keyword(s):  
Functional Performance ◽  
Knee Extension ◽  
Muscle Performance ◽  
Facilitatory Effect ◽  
Control Group ◽  
Older Population ◽  
Timed Up And Go ◽  
Performance Tasks ◽  
Knee Extension Strength ◽  
And Performance

This study was designed to investigate the effects of vibration on muscle performance and mobility in a healthy, untrained, older population. Forty-three participants (23 men, 20 women, 66–85 y old) performed tests of sit-to-stand (STS), 5- and 10-m fast walk, timed up-and-go test, stair mobility, and strength. Participants were randomly assigned to a vibration group, an exercise-without-vibration group, or a control group. Training consisted of 3 sessions/wk for 2 mo. After training, the vibration and exercise groups showed improved STS (12.4%, 10.2%), 5-m fast walk (3.0%, 3.7%), and knee-extension strength (8.1%, 7.2%) compared with the control (p< 0.05). Even though vibration training improved lower limb strength, it did not appear to have a facilitatory effect on functional-performance tasks compared with the exercise-without-vibration group. Comparable mobility and performance changes between the experimental groups suggest that improvements are linked with greater knee-extension strength and largely attributed to the unloaded squats performed by both exercise groups.

scholarly journals Mechanical and Microstructural Characteristics of Calcium Sulfoaluminate Cement Exposed to Early-Age Carbonation Curing

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3515
Author(s):  
Weikang Wang ◽  
Xuanchun Wei ◽  
Xinhua Cai ◽  
Hongyang Deng ◽  
Bokang Li
Keyword(s):  
Cement Paste ◽  
Pore Diameter ◽  
Performance Enhancement ◽  
Diameter Distribution ◽  
Early Age ◽  
Calcium Sulfoaluminate ◽  
Starting Point ◽  
And Performance ◽  
Curing Pressure ◽  
Carbonation Curing

: The early-age carbonation curing technique is an effective way to improve the performance of cement-based materials and reduce their carbon footprint. This work investigates the early mechanical properties and microstructure of calcium sulfoaluminate (CSA) cement specimens under early-age carbonation curing, considering five factors: briquetting pressure, water–binder (w/b) ratio, starting point of carbonation curing, carbonation curing time, and carbonation curing pressure. The carbonization process and performance enhancement mechanism of CSA cement are analyzed by mercury intrusion porosimetry (MIP), thermogravimetry and derivative thermogravimetry (TG-DTG) analysis, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that early-age carbonation curing can accelerate the hardening speed of CSA cement paste, reduce the cumulative porosity of the cement paste, refine the pore diameter distribution, and make the pore diameter distribution more uniform, thus greatly improving the early compressive strength of the paste. The most favorable w/b ratio for the carbonization reaction of CSA cement paste is between 0.15 and 0.2; the most suitable carbonation curing starting time point is 4 h after initial hydration; the carbonation curing pressure should be between 3 and 4 bar; and the most appropriate time for carbonation curing is between 6 and 12 h.

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