scholarly journals Quantification of Inter-Limb Symmetries With Rate of Force Development and Relaxation Scaling Factor

2021 ◽  
Vol 12 ◽  
Author(s):  
Darjan Smajla ◽  
Jure Žitnik ◽  
Nejc Šarabon
Keyword(s):  
Muscle Contraction ◽  
Outcome Measures ◽  
Force Production ◽  
Scaling Factor ◽  
Rate Of Force Development ◽  
Cross Sectional ◽  
Tennis Players ◽  
Force Development ◽  
Gender And Sports ◽  
Contraction And Relaxation

The inter-limb (a)symmetries have been most often assessed with the tests that quantify the maximal muscle capacity. However, the rapid force production and relaxation during submaximal tasks is equally important for successful sports performance. This can be evaluated with an established rate of force development and relaxation scaling factor (RFD-SF/RFR-SF). The aims of our study were (1) to assess the intra-session reliability of shortened RFD-SF/RFR-SF protocol and its absolute and symmetry outcome measures, (2) to compare the main absolute RFD-SF/RFR-SF outcome measures (slopes of RFD-SF and RFR-SF: kRTD–SF and kRFR–SF, theoretical peak RFD/RFR: TPRFD and TPRFR) across gender and sports groups, and (3) to compare inter-limb symmetries across gender and sports groups for main outcome measures (kRFD–SF, kRFR–SF, TPRFD, and TPRFR). A cross-sectional study was conducted on a group of young health participants (basketball and tennis players, and students): 30 in the reliability study and 248 in the comparison study. Our results showed good to excellent relative and excellent absolute reliability for the selected absolute and symmetry outcome measures (kRFD–SF, kRFR–SF, TPRFD, and TPRFR). We found significantly higher absolute values for kRFD–SF and TPRFD in males compared to females for the preferred (kRFD–SF: 9.1 ± 0.9 vs. 8.6 ± 0.9/s) and the non-preferred leg (kRFD–SF: 9.1 ± 0.9 vs. 8.5 ± 0.8/s), while there was no effect of sport. Significantly lower symmetry values for kRFR–SF (88.4 ± 8.6 vs. 90.4 ± 8.0%) and TPRFR (90.9 ± 6.8 vs. 92.5 ± 6.0%) were found in males compared to females. Moreover, tennis players had significantly higher symmetry values for kRFR–SF (91.1 ± 7.7%) and TPRFR (93.1 ± 6.0%) compared to basketball players (kRFR–SF: 88.4 ± 8.7% and TPRFR: 90.9 ± 6.7%) and students (kRFR–SF: 87.6 ± 8.7% and TPRFR: 90.5 ± 6.7%). Our results suggest that the reduced RFD-SF/RFR-SF protocol is a valuable and useful tool for inter-limb (a)symmetry evaluation. Differences in symmetry values in kRFR–SF and TPRFR (relaxation phase) were found between different sports groups. These may be explained by different mechanisms underlying the muscle contraction and relaxation. We suggest that muscle contraction and relaxation should be assessed for in-depth inter-limb symmetry investigation.

scholarly journals Advancements in the Protocol for Rate of Force Development/Relaxation Scaling Factor Evaluation

2021 ◽  
Vol 15 ◽  
Author(s):  
Darjan Smajla ◽  
Jure Žitnik ◽  
Nejc Šarabon
Keyword(s):  
Outcome Measure ◽  
Isometric Force ◽  
Cross Sectional Study ◽  
Scaling Factor ◽  
Rate Of Force Development ◽  
Knee Extensors ◽  
Cross Sectional ◽  
Force Development ◽  
Wide Range ◽  
Neuromuscular Assessment

Brief submaximal actions are important for wide range of functional movements. Until now, rate of force development and relaxation scaling factor (RFD-SF and RFR-SF) have been used for neuromuscular assessment using 100–120 isometric pulses which requires a high level of attention from the participant and may be influenced by physiological and/or psychological fatigue. All previous studies have been conducted on a smaller number of participants which calls into question the eligibility of some of the outcome measures reported to date. Our aims were: (1) to find the smallest number of rapid isometric force pulses at different force amplitudes is still valid and reliable for RFD-SF slope (kRFD–SF) and RFR-SF slope (kRFR–SF) calculation, (2) to introduce a new outcome measure – theoretical peak of rate of force development/relaxation (TPRFD and TPRFR) and (3) to investigate differences and associations between kRFD–SF and kRFR–SF. A cross-sectional study was conducted on a group of young healthy participants; 40 in the reliability study and 336 in the comparison/association study. We investigated the smallest number of rapid isometric pulses for knee extensors that still provides excellent reliability of the calculated kRFD–SF and kRFR–SF (ICC2,1 ≥ 0.95, CV < 5%). Our results showed excellent reliability of the reduced protocol when 36 pulses (nine for each of the four intensity ranges) were used for the calculations of kRFD–SF and kRFR–SF. We confirmed the negligibility of the y-intercepts and confirmed the reliability of the newly introduced TPRFD and TPRFR. Large negative associations were found between kRFD–SF and kRFR–SF (r = 0.502, p < 0.001), while comparison of the absolute values showed a significantly higher kRFD–SF (8.86 ± 1.0/s) compared to kRFR–SF (8.03 ± 1.3/s) (p < 0.001). The advantage of the reduced protocol (4 intensities × 9 pulses = 36 pulses) is the shorter assessment time and the reduction of possible influence of fatigue. In addition, the introduction of TPRFD and TPRFR as an outcome measure provides valuable information about the participant’s maximal theoretical RFD/RFR capacity. This can be useful for the assessment of maximal capacity in people with various impairments or pain problems.

Age- and Sex-Related Differences in the Maximum Muscle Performance and Rate of Force Development Scaling Factor of Precision Grip Muscles

Motor Control ◽  
2020 ◽  
Vol 24 (2) ◽  
pp. 274-290
Author(s):  
Talyene G.C. Corrêa ◽  
Stephanie V.S. Donato ◽  
Kauê C.A. Lima ◽  
Ronaldo V. Pereira ◽  
Mehmet Uygur ◽  
...  
Keyword(s):  
Grip Force ◽  
Isometric Force ◽  
Maximum Voluntary Contraction ◽  
Precision Grip ◽  
Voluntary Contraction ◽  
Scaling Factor ◽  
Rate Of Force Development ◽  
Muscle Performance ◽  
Force Development ◽  
Age And Sex

The aim of this study was to explore the effects of age and sex on the rate of force development scaling factor (RFD-SF) and maximum performance (i.e., maximum grip force [GFMax] and maximum rate of grip force development [RGFDMax]) of precision handgrip muscles. Sixty-four subjects, allocated in four groups according to their age and sex, were asked to hold an instrumented handle with the tip of the digits and perform two tests: maximum voluntary contraction and RFD-SF tests. In the maximum voluntary contraction test, GFMax and RGFDMax were assessed. In the RFD-SF test, the subjects generated quick isometric force pulses to target amplitudes varying between 20% and 100% of their GFMax. The RFD-SF and R2 values were obtained from the linear relationship between the peak values of the force pulses and the corresponding peak values of the rate of force development. Younger adults and males produced higher GFMax and RGFDMax and presented higher R2 and RFD-SF than older adults and females, respectively. No correlations between GFMax and RFD-SF and between RGFDMax and RFD-SF were observed.

The rate of force development scaling factor (RFD-SF): protocol, reliability, and muscle comparisons

2011 ◽  
Vol 212 (3) ◽  
pp. 359-369 ◽  
Author(s):  
Maria Bellumori ◽  
Slobodan Jaric ◽  
Christopher A. Knight
Keyword(s):  
Scaling Factor ◽  
Rate Of Force Development ◽  
Force Development

The Optimal Joint Angle for Adductor Pollicis Force Production in Men and Women

1999 ◽  
Vol 24 (6) ◽  
pp. 570-580 ◽  
Author(s):  
David Ditor ◽  
Audrey Hicks
Keyword(s):  
Gender Difference ◽  
Key Words ◽  
Joint Angle ◽  
Force Production ◽  
Adductor Pollicis ◽  
Rate Of Force Development ◽  
Men And Women ◽  
Twitch Force ◽  
Force Development ◽  
Nondominant Hand

The purpose of this study was to determine the joint angle that allows for the greatest MVC and evoked twitch forces from the adductor pollicis (AP), and also whether there is a gender difference in either the above forces or the optimum thumb angle. Ten men (25.2 yrs) and 10 women (27.6 yrs) participated. The nondominant hand was placed palm-down with the thumb fixed at four angles of abduction (55, 70, 85, 100°). Male MVC forces were significantly greater than female, and there was no significant effect of joint angle on MVC force in either gender. For the evoked twitch, men were significantly stronger than women when tested at the 100 and 85° angles, and a significant effect was found for joint angle such that the lowest twitch force occurred at 55°. Men also tended to have a greater rate of force development than women (p = 0.07). These data suggest that studies using the AP muscle in stimulated and voluntary paradigms should use a thumb angle between 70 and 100° of abduction, or approximately 85°, and that the same angle can be used for both men and women. Key words: evoked twitch, MVC, gender, EMG, rate of force development

Aging, muscle fiber type, and contractile function in sprint-trained athletes

2006 ◽  
Vol 101 (3) ◽  
pp. 906-917 ◽  
Author(s):  
Marko T. Korhonen ◽  
Alexander Cristea ◽  
Markku Alén ◽  
Keijo Häkkinen ◽  
Sarianna Sipilä ◽  
...  
Keyword(s):  
Fiber Type ◽  
Cross Sectional Area ◽  
Rate Of Force Development ◽  
Knee Extensors ◽  
Type I ◽  
Sectional Area ◽  
Cross Sectional ◽  
Specific Tension ◽  
Force Development ◽  
Aging Muscle

Biopsy samples were taken from the vastus lateralis of 18- to 84-yr-old male sprinters ( n = 91). Fiber-type distribution, cross-sectional area, and myosin heavy chain (MHC) isoform content were identified using ATPase histochemistry and SDS-PAGE. Specific tension and maximum shortening velocity ( Vo) were determined in 144 single skinned fibers from younger (18–33 yr, n = 8) and older (53–77 yr, n = 9) runners. Force-time characteristics of the knee extensors were determined by using isometric contraction. The cross-sectional area of type I fibers was unchanged with age, whereas that of type II fibers was reduced ( P < 0.001). With age there was an increased MHC I ( P < 0.01) and reduced MHC IIx isoform content ( P < 0.05) but no differences in MHC IIa. Specific tension of type I and IIa MHC fibers did not differ between younger and older subjects. Vo of fibers expressing type I MHC was lower ( P < 0.05) in older than in younger subjects, but there was no difference in Vo of type IIa MHC fibers. An aging-related decline of maximal isometric force ( P < 0.001) and normalized rate of force development ( P < 0.05) of knee extensors was observed. Normalized rate of force development was positively associated with MHC II ( P < 0.05). The sprint-trained athletes experienced the typical aging-related reduction in the size of fast fibers, a shift toward a slower MHC isoform profile, and a lower Vo of type I MHC fibers, which played a role in the decline in explosive force production. However, the muscle characteristics were preserved at a high level in the oldest runners, underlining the favorable impact of sprint exercise on aging muscle.

The differential effect of metabolic alkalosis on maximum force and rate of force development during repeated, high-intensity cycling

2013 ◽  
Vol 115 (11) ◽  
pp. 1634-1640 ◽  
Author(s):  
Jason C. Siegler ◽  
Paul W. M. Marshall ◽  
Sean Raftry ◽  
Cristy Brooks ◽  
Ben Dowswell ◽  
...  
Keyword(s):  
Sodium Bicarbonate ◽  
High Intensity ◽  
Differential Effect ◽  
Force Production ◽  
Rate Of Force Development ◽  
Maximum Force ◽  
Whole Body ◽  
Peak Power Output ◽  
Force Development ◽  
Maximal Force

The purpose of this investigation was to assess the influence of sodium bicarbonate supplementation on maximal force production, rate of force development (RFD), and muscle recruitment during repeated bouts of high-intensity cycling. Ten male and female ( n = 10) subjects completed two fixed-cadence, high-intensity cycling trials. Each trial consisted of a series of 30-s efforts at 120% peak power output (maximum graded test) that were interspersed with 30-s recovery periods until task failure. Prior to each trial, subjects consumed 0.3 g/kg sodium bicarbonate (ALK) or placebo (PLA). Maximal voluntary contractions were performed immediately after each 30-s effort. Maximal force (Fmax) was calculated as the greatest force recorded over a 25-ms period throughout the entire contraction duration while maximal RFD (RFDmax) was calculated as the greatest 10-ms average slope throughout that same contraction. Fmax declined similarly in both the ALK and PLA conditions, with baseline values (ALK: 1,226 ± 393 N; PLA: 1,222 ± 369 N) declining nearly 295 ± 54 N [95% confidence interval (CI) = 84–508 N; P < 0.006]. RFDmax also declined in both trials; however, a differential effect persisted between the ALK and PLA conditions. A main effect of condition was observed across the performance time period, with RFDmax on average higher during ALK (ALK: 8,729 ± 1,169 N/s; PLA: 7,691 ± 1,526 N/s; mean difference between conditions 1,038 ± 451 N/s, 95% CI = 17–2,059 N/s; P < 0.048). These results demonstrate a differential effect of alkalosis on maximum force vs. maximum rate of force development during a whole body fatiguing task.

scholarly journals Phase-Specific Changes in Rate of Force Development and Muscle Morphology Throughout a Block Periodized Training Cycle in Weightlifters

Sports ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 129 ◽  
Author(s):  
Dylan G. Suarez ◽  
Satoshi Mizuguchi ◽  
William Guy Hornsby ◽  
Aaron J. Cunanan ◽  
Donald J. Marsh ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
High Volume ◽  
Rate Of Force Development ◽  
Cross Sectional ◽  
Force Development ◽  
Training Cycle ◽  
Morphological Adaptations ◽  
Single Block ◽  
Collegiate Weightlifters ◽  
Periodized Training

The purpose of this study was to investigate the kinetic and morphological adaptations that occur during distinct phases of a block periodized training cycle in weightlifters. Athlete monitoring data from nine experienced collegiate weightlifters was used. Isometric mid-thigh pull (IMTP) and ultrasonography (US) results were compared to examine the effects of three specific phases of a training cycle leading up to a competition. During the high volume strength-endurance phase (SE) small depressions in rate of force development (RFD) but statistically significant (p ≤ 0.05) increases in vastus lateralis cross-sectional area (CSA), and body mass (BM) were observed. The lower volume higher intensity strength-power phase (SP) caused RFD to rebound above pre-training cycle values despite statistically significant reductions in CSA. Small to moderate increases only in the earlier RFD time bands (<150 ms) occurred during the peak/taper phase (PT) while CSA and BM were maintained. Changes in IMTP RFD and CSA from US reflected the expected adaptations of block periodized training phases. Changes in early (<100 ms) and late (≥150 ms) RFD time bands may not occur proportionally throughout different training phases. Small increases in RFD and CSA can be expected in well-trained weightlifters throughout a single block periodized training cycle.

The effect of rate of force development on maximal force production: acute and training-related aspects

2007 ◽  
Vol 99 (6) ◽  
pp. 605-613 ◽  
Author(s):  
Andreas Holtermann ◽  
Karin Roeleveld ◽  
Beatrix Vereijken ◽  
Gertjan Ettema
Keyword(s):  
Force Production ◽  
Rate Of Force Development ◽  
Force Development ◽  
Maximal Force ◽  
And Training
Sign in / Sign up

Export Citation Format

Share Document