scholarly journals Effect of Sampling Frequency on Isometric Midthigh-Pull Kinetics

2016 ◽  
Vol 11 (2) ◽  
pp. 255-260 ◽  
Author(s):  
Thomas Dos’Santos ◽  
Paul A. Jones ◽  
Jonathan Kelly ◽  
John J. McMahon ◽  
Paul Comfort ◽  
...  
Keyword(s):  
Repeated Measures ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Rugby League ◽  
Sampling Frequency ◽  
Peak Force ◽  
Specific Force ◽  
Skeletal Muscle Function ◽  
Force Time ◽  
Time Specific

Purpose:Skeletal-muscle function can be evaluated using force–times curves generated via the isometric midthigh pull (IMTP). Various sampling frequencies (500–1000 Hz) have been used for IMTP assessments; however, no research has investigated the influence of sampling frequency on IMTP kinetics. Therefore, the purpose of this study was to investigate the influence of sampling frequency on kinetic variables during the IMTP, including peak force, time-specific force values (100, 150, and 200 ms), and rate of force development (RFD) at 3 time bands (0–100, 0–150, 0–200 ms).Methods:Academy rugby league players (n = 30, age 17.5 ± 1.1 y, height 1.80 ± 0.06 m, mass 85.4 ± 10.3 kg) performed 3 IMTP trials on a force platform sampling at 2000 Hz, which was subsequently down-sampled to 1500, 1000, and 500 Hz for analysis.Results:Intraclass correlation coefficients (ICC) and coefficients of variation (CV) demonstrated high within-session reliability for all force and RFD variables across all sampling frequencies (ICC ≥ .80, CV ≤ 10.1%). Repeated-measures analysis of variance revealed no significant differences (P > .05, Cohen d ≤ 0.009) in kinetic variables between sampling frequencies. Overall, high reliability was observed across all sampling frequencies for all kinetic variables, with no significant differences (P > .05) for each kinetic variable across sampling frequencies.Conclusions:Practitioners and scientists may consider sampling as low as 500 Hz when measuring peak force, time-specific force values, and RFD at predetermined time bands during the IMTP for accurate and reliable data.

scholarly journals Effect of Sampling Frequency on Isometric Midthigh-Pull Kinetics

2019 ◽  
Vol 14 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Thomas Dos’Santos ◽  
Paul A. Jones ◽  
Jonathan Kelly ◽  
John J. McMahon ◽  
Paul Comfort ◽  
...  
Keyword(s):  
Repeated Measures ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Rugby League ◽  
Sampling Frequency ◽  
Peak Force ◽  
Specific Force ◽  
Skeletal Muscle Function ◽  
Force Time ◽  
Time Specific

Purpose: Skeletal-muscle function can be evaluated using force-times curves generated via the isometric midthigh pull (IMTP). Various sampling frequencies (500–1000 Hz) have been used for IMTP assessments; however, no research has investigated the influence of sampling frequency on IMTP kinetics. Therefore, the purpose of this study was to investigate the influence of sampling frequency on kinetic variables during the IMTP, including peak force, time-specific force values (100, 150, and 200 ms), and rate of force development (RFD) at 3 time bands (0–100, 0–150, 0–200 ms). Methods: Academy rugby league players (n = 30, age 17.5 ± 1.1 y, height 1.80 ± 0.06 m, mass 85.4 ± 10.3 kg) performed 3 IMTP trials on a force platform sampling at 2000 Hz, which was subsequently down-sampled to 1500, 1000, and 500 Hz for analysis. Results: Intraclass correlation coefficients (ICC) and coefficients of variation (CV) demonstrated high within-session reliability for all force and RFD variables across all sampling frequencies (ICC ≥ .80, CV ≤ 14.4%) except RFD 0–100 and 0–150, which demonstrated slightly greater levels of variance (CV = 18.0–24.1%). Repeated-measures analysis of variance revealed no significant differences (P > .05, Cohen d ≤ 0.0171) in kinetic variables between sampling frequencies. Overall, high reliability was observed across all sampling frequencies for peak force, time-specific force, and RFD 0- to 200-ms variables, with no significant differences (P > .05) for each kinetic variable across sampling frequencies. Conclusions: Practitioners and scientists may consider sampling as low as 500 Hz when measuring peak force, time-specific force values, and RFD at predetermined time bands during the IMTP for accurate and reliable data.

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.

Bioimpedance Spectroscopy Is a Valid and Reliable Measure of Edema Following Hand Burn Injury (Part 1—Method Validation)

2020 ◽  
Vol 41 (4) ◽  
pp. 780-787 ◽  
Author(s):  
Dale O Edwick ◽  
Dana A Hince ◽  
Jeremy M Rawlins ◽  
Fiona M Wood ◽  
Dale W Edgar
Keyword(s):  
Repeated Measures ◽  
Burn Injury ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Reliability And Validity ◽  
Whole Body ◽  
Bioimpedance Spectroscopy ◽  
Water Displacement ◽  
Reliable Measure ◽  
Minimum Detectable Difference

Abstract The assessment of swelling following burn injury is complicated by the presence of wounds and dressings and due to patients experiencing significant pain and impaired movement. There remains a lack of sensitive objective measures for edema in patients presenting with hand burn injury. Bioimpedance spectroscopy (BIS) is a measure of body composition that has been demonstrated by our group to be reliable for measuring whole body and limb edema during resuscitation and to be sensitive to edema changes within healing wounds. The aim of this study was to determine the reliability and validity of BIS as a measure of edema following hand burn injury specifically. One hundred patients presenting with burn injury including a portion of a hand were recruited to this trial. Repeated measures of the hand were recorded using a novel application of BIS and in parallel with water displacement volumetry (WDV). The results were analyzed using mixed-effects regressions. Paired repeated measures were obtained for 195 hands, using four electrode configurations. BIS demonstrated high reliability in measuring hand BIS—Intraclass Correlation Coefficient 0.995 to 0.999 (95% CI 0.992–1.000) and sensitivity—Minimum Detectable Difference 0.74 to 3.86 Ω (0.09–0.48 Ω/cm). A strong correlation was shown with WDV, Pearson’s r = −0.831 to −0.798 (P < .001). BIS is a sensitive and reliable measure of edema following acute hand burn injury.

scholarly journals The Effect of Altering Body Posture and Barbell Position on the Between-Session Reliability of Force-Time Curve Characteristics in the Isometric Mid-Thigh Pull

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 162 ◽  
Author(s):  
Stuart Guppy ◽  
Claire Brady ◽  
Yosuke Kotani ◽  
Michael Stone ◽  
Nikola Medic ◽  
...  
Keyword(s):  
Training Programs ◽  
Body Posture ◽  
Peak Force ◽  
Time Curve ◽  
Body Postures ◽  
Time To Peak ◽  
Testing Protocol ◽  
Force Peak ◽  
Force Time ◽  
Time Specific

Seventeen strength and power athletes (n = 11 males, 6 females; height: 177.5 ± 7.0 cm, 165.8 ± 11.4 cm; body mass: 90.0 ± 14.1 kg, 66.4 ± 13.9 kg; age: 30.6 ± 10.4 years, 30.8 ± 8.7 years), who regularly performed weightlifting movements during their resistance training programs, were recruited to examine the effect of altering body posture and barbell position on the between-session reliability of force-time characteristics generated in the isometric mid-thigh pull (IMTP). After participants were familiarised with the testing protocol, they undertook two testing sessions which were separated by seven days. In each session, the participants performed three maximal IMTP trials in each of the four testing positions examined, with the order of testing randomized. In each position, no significant differences were found between sessions for all force-time characteristics (p = >0.05). Peak force (PF), time-specific force (F50, F90, F150, F200, F250) and IMP time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) were reliable across each of the four testing positions (ICC ≥ 0.7, CV ≤ 15%). Time to peak force, peak RFD, RFD time-bands (0–50, 0–90, 0–150, 0–200, 0–250 ms) and peak IMP were unreliable regardless of the testing position used (ICC = <0.7, CV = >15%). Overall, the use of body postures and barbell positions during the IMTP that do not correspond to the second pull of the clean have no adverse effect on the reliability of the force-time characteristics generated.

Reliability of electromyographic and force measures during prone isometric back extension in subjects with and without low back pain

2008 ◽  
Vol 33 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Mark J. Pitcher ◽  
David G. Behm ◽  
Scott N. MacKinnon
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Repeated Measures ◽  
Muscle Activation ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Erector Spinae ◽  
Emg Activity ◽  
Control Group ◽  
Low Back

Maximal voluntary isometric activations (MVIA) are frequently used as inputs for models attempting to predict muscle force and as normalization values in studies assessing muscle function. However, pain may adversely affect maximal muscle activation. The purpose of this study was to assess reliability of MVIA force and electromyographic (EMG) activity during prone isometric back extension in subjects with and without low back pain (LBP). A novel sub-maximal method using the percentages of the estimated mass of the head–arms–trunk (HAT) segment was also investigated. Repeated measures on 20 male volunteers divided into an LBP (n = 10) and a control group (n = 10) were made on 4 occasions. Force and EMG activity were recorded bilaterally from upper lumbar erector spinae (ULES), lower lumbar erector spinae (LLES), and biceps femoris (BF). Subjects exerted a maximal extension effort against a harness assembly that was attached to a force transducer. Submaximal exertions were also performed with an additional resistance of 100%, 110%, 120%, 130%, 140%, 150%, 160%, and 170% of HAT. Mean MVIA forces were significantly (p ≤ 0.05) lower in LBP vs. control. Intraclass correlation coefficients (ICC) for MVIA force, right and left ULES, and LLES EMG indicated high reliability in controls (R > 0.90), but were significantly less in LBP (R = 0.36–0.80). EMG of BF demonstrated excellent reliability across both groups (R > 0.90). The resistance at 100% HAT demonstrated the highest reliability for LBP patients, whereas higher percentages of HAT showed either similar or higher reliability for controls. Force output and back EMG activity are less reliable with LBP individuals and should be taken into consideration when testing.

scholarly journals Assessing Muscle-Strength Asymmetry via a Unilateral-Stance Isometric Midthigh Pull

2017 ◽  
Vol 12 (4) ◽  
pp. 505-511 ◽  
Author(s):  
Thomas Dos’Santos ◽  
Christopher Thomas ◽  
Paul A. Jones ◽  
Paul Comfort
Keyword(s):  
College Athletes ◽  
Isometric Force ◽  
Intraclass Correlation ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Rugby League ◽  
Intraclass Correlation Coefficients ◽  
Male College ◽  
Strength Asymmetry ◽  
Force Time

Purpose:To investigate the within-session reliability of bilateral- and unilateral-stance isometric midthigh-pull (IMTP) force–time characteristics including peak force (PF), relative PF, and impulse at time bands (0–100, 0–200, 0–250, and 0–300 milliseconds) and to compare isometric force–time characteristics between right and left and dominant (D) and nondominant (ND) limbs.Methods:Professional male rugby league and multisport male college athletes (N = 54; age, 23.4 ± 4.2 y; height, 1.80 ± 0.05 m; mass, 88.9 ± 12.9 kg) performed 3 bilateral IMTP trials and 6 unilateral-stance IMTP trials (3 per leg) on a force plate sampling at 600 Hz.Results:Intraclass correlation coefficients (ICCs) and coefficients of variation (CVs) demonstrated high within-session reliability for bilateral and unilateral IMTP PF (ICC = .94, CV = 4.7–5.5%). Lower reliability measures and greater variability were observed for bilateral and unilateral IMTP impulse at time bands (ICC = .81–.88, CV = 7.7–11.8%). Paired-sample t tests and Cohen d effect sizes revealed no significant differences for all isometric force–time characteristics between right and left limbs in male college athletes (P >.05, d ≤ 0.32) and professional rugby league players (P > .05, d ≤ 0.11); however, significant differences were found between D and ND limbs in male college athletes (P < .001, d = 0.43–0.91) and professional rugby league players (P < .001, d = 0.27–0.46).Conclusion:This study demonstrated high within-session reliability for unilateral-stance IMTP PF, revealing significant differences in isometric force–time characteristics between D and ND limbs in male athletes.

scholarly journals Force-Time Differences between Ballistic and Non-Ballistic Half-Squats

Sports ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 79 ◽  
Author(s):  
Timothy Suchomel ◽  
Christopher Taber ◽  
Christopher Sole ◽  
Michael Stone
Keyword(s):  
Repeated Measures ◽  
Training Stimulus ◽  
Peak Force ◽  
Effect Sizes ◽  
Practical Significance ◽  
Repetition Maximum ◽  
Cohen’S D ◽  
Main Effect ◽  
Force Time ◽  
Post Hoc

The purpose of this study was to examine the force-time differences between concentric-only half-squats (COHS) performed with ballistic (BAL) or non-ballistic (NBAL) intent across a range of loads. Eighteen resistance-trained men performed either BAL or NBAL COHS at 30%, 50%, 70%, and 90% of their one repetition maximum (1RM) COHS. Relative peak force (PF) and relative impulse from 0–50 ms (Imp50), 0–90 ms (Imp90), 0–200 ms (Imp200), and 0–250 ms (Imp250) were compared using a series of 2 × 4 (intent × load) repeated measures ANOVAs with Bonferroni post hoc tests. Cohen’s d effect sizes were calculated to provide measures of practical significance between the BAL and NBAL COHS and each load. BAL COHS produced statistically greater PF than NBAL COHS at 30% (d = 3.37), 50% (d = 2.88), 70% (d = 2.29), and 90% 1RM (d = 1.19) (all p < 0.001). Statistically significant main effect differences were found between load-averaged BAL and NBAL COHS for Imp90 (p = 0.006, d = 0.25), Imp200 (p = 0.001, d = 0.36), and Imp250 (p < 0.001, d = 0.41), but not for Imp50 (p = 0.018, d = 0.21). Considering the greater PF and impulse observed during the BAL condition, performing COHS with BAL intent may provide a favorable training stimulus compared to COHS performed with NBAL intent.

Consistency of Peak and Mean Concentric and Eccentric Force Using a Novel Squat Testing Device

2014 ◽  
Vol 30 (2) ◽  
pp. 322-325 ◽  
Author(s):  
Matt S. Stock ◽  
Micheal J. Luera
Keyword(s):  
High Reliability ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Peak Force ◽  
Isokinetic Dynamometry ◽  
Intraclass Correlation Coefficients ◽  
Force Curves ◽  
Mean Differences ◽  
Test Retest Reliability ◽  
Muscle Actions

The ability to examine force curves from multiple-joint assessments combines many of the benefits of dynamic constant external resistance exercise and isokinetic dynamometry. The purpose of this investigation was to examine test-retest reliability statistics for peak and mean force using the Exerbotics eSQ during maximal concentric and eccentric squats. Seventeen resistance-trained men (mean ± SD age = 21 ± 2 years) visited the laboratory on two occasions. For each trial, the subjects performed two maximal concentric and eccentric squats, and the muscle actions with the highest force values were analyzed. There were no mean differences between the trials (P> .05), and the effect sizes were < 0.12. When the entire force curve was examined, the intraclass correlation coefficients (model 2,1) and standard errors of measurement, respectively, were concentric peak force = 0.743 (8.8%); concentric mean force = 0.804 (6.0%); eccentric peak force = 0.696 (10.6%); eccentric mean force = 0.736 (9.6%). These findings indicated moderate-to-high reliability for the peak and mean force values obtained from the Exerbotics eSQ during maximal squat testing. The analysis of force curves from multiple-joint testing provides researchers and practitioners with a reliable means of assessing performance, especially during concentric muscle actions.

scholarly journals Is there a relationship between the overhead press and split jerk maximum performance? Influence of sex

2021 ◽  
pp. 174795412110204
Author(s):  
Marcos A Soriano ◽  
G Gregory Haff ◽  
Paul Comfort ◽  
Francisco J Amaro-Gahete ◽  
Antonio Torres-González ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Body Mass ◽  
Upper Limb ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Training Experience ◽  
Maximum Performance ◽  
Repetition Maximum ◽  
Intraclass Correlation Coefficients

The aims of this study were to (I) determine the differences and relationship between the overhead press and split jerk performance in athletes involved in weightlifting training, and (II) explore the magnitude of these differences in one-repetition maximum (1RM) performances between sexes. Sixty-one men (age: 30.4 ± 6.7 years; height: 1.8 ± 0.5 m; body mass 82.5 ± 8.5 kg; weightlifting training experience: 3.7 ± 3.5 yrs) and 21 women (age: 29.5 ± 5.2 yrs; height: 1.7 ± 0.5 m; body mass: 62.6 ± 5.7 kg; weightlifting training experience: 3.0 ± 1.5 yrs) participated. The 1RM performance of the overhead press and split jerk were assessed for all participants, with the overhead press assessed on two occasions to determine between-session reliability. The intraclass correlation coefficients (ICC) and 95% confidence intervals showed a high reliability for the overhead press ICC = 0.98 (0.97 – 0.99). A very strong correlation and significant differences were found between the overhead press and split jerk 1RM performances for all participants (r = 0.90 [0.93 – 0.85], 60.2 ± 18.3 kg, 95.7 ± 29.3 kg, p ≤ 0.001). Men demonstrated stronger correlations between the overhead press and split jerk 1RM performances (r = 0.83 [0.73-0.90], p ≤ 0.001) compared with women (r = 0.56 [0.17-0.80], p = 0.008). These results provide evidence that 1RM performance of the overhead press and split jerk performance are highly related, highlighting the importance of upper-limb strength in the split jerk maximum performance.

scholarly journals Changes in Maximal Strength and Home Run Performance in NCAA Division I Baseball Players Across 3 Competitive Seasons: A Descriptive Study

2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
W. Guy Hornsby ◽  
Abigail L. Tice ◽  
Jason D. Stone ◽  
Justin J. Merrigan ◽  
Joshua Hagen ◽  
...  
Keyword(s):  
Ncaa Division I ◽  
Repeated Measures ◽  
National Collegiate Athletic Association ◽  
Descriptive Study ◽  
Peak Force ◽  
Division I ◽  
Maximal Strength ◽  
Baseball Players ◽  
Repeated Measures Analysis ◽  
Division 1

The purpose of this longitudinal, descriptive study was to observe changes in maximal strength measured via isometric clean grip mid-thigh pull and home runs (total and home runs per game) across three years of training and three competitive seasons for four National Collegiate Athletic Association (NCAA) Division 1 baseball players. A one-way repeated measures analysis of variance (ANOVA) was performed, revealing significant univariate effects of time for peak force (PF) (p = 0.003) and peak force allometrically scaled (PFa) (p = 0.002). Increases in PF were noted from season 1 to season 2 (p = 0.031) and season 3 (p = 0.004), but season 2 was not significantly different than season 3 (p = 0.232). Additionally, increases in PFa were noted from season 1 to season 2 (p = 0.010) and season 3 (p < 0.001), but season 2 was not significantly different than season 3 (p = 0.052). Home runs per game rose from the 2009 (0.32) to 2010 season (1.35) and dropped during the 2011 season (1.07). A unique aspect of the study involves 2010 being the season in which ball-bat coefficient of restitution (BBCOR) bats were introduced to the NCAA competition.

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