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

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.

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Achieving the Split Position in a Saut de Chat Leap

Medical Problems of Performing Artists ◽

10.21091/mppa.2020.2011 ◽

2020 ◽

Vol 35 (2) ◽

pp. 68-72

Author(s):

Danielle N Jarvis ◽

Kornelia Kulig

Keyword(s):

Repeated Measures ◽

Center Of Mass ◽

Peak Height ◽

Knee Joints ◽

Similar Time ◽

Dance Training ◽

Main Effect ◽

Hip Flexion ◽

Post Hoc ◽

Coordination Patterns

OBJECTIVES: Dancers frequently perform complex jumping skills that involve achieving specific body positions while in the air. An examination of how skilled dancers achieve these aesthetic demands can provide information useful for dance training. The purpose of this study was to examine the temporal coordination of the hip and knee joints during the flight phase of a saut de chat leap, where dancers aim to achieve a split position in the air when the center of mass (COM) reaches peak height. METHODS: Thirty healthy, experienced dancers with 22.5±4.5 years of dance training performed 5 saut de chat leaps. The timing of peak hip and knee joint angles and velocities for the takeoff and leading legs were extracted and compared to the time when COM reached peak height in the leap using a repeated measures ANOVA, with post-hoc comparisons made using paired t-tests. RESULTS: Dancers demonstrated significant differences in timing associated with achieving the split position (main effect p<0.001), with only peak leading leg hip flexion occurring at a similar time to the COM reaching peak height (paired t-test p=0.074). CONCLUSIONS: The results of this study provide insight into coordination patterns used by trained dancers. Trained dancers demonstrate patterns in timing that may be important for successful performance. The hip and knee coordination patterns during flight demonstrate how dancers work to achieve the desired aesthetics of a saut de chat leap. However, it appears that dancers do not reach the full split position at the height of the leap, as would be aesthetically desirable.

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Repetitions to failure increase pectoralis major activation with similar neuromuscular fatigue in trained men

Journal of Physical Education ◽

10.4025/jphyseduc.v32i1.3214 ◽

2020 ◽

Vol 32 (1) ◽

Author(s):

Mateus Camargos Gomes ◽

Lucas Túlio Lacerda ◽

Marina Gurgel Simões ◽

Rodrigo César Ribeiro Diniz ◽

Mauro Heleno Chagas ◽

...

Keyword(s):

Repeated Measures ◽

Muscle Activation ◽

Rest Period ◽

Neuromuscular Fatigue ◽

Pectoralis Major ◽

Effective Strategy ◽

Repetition Maximum ◽

Post Hoc ◽

Repetitions To Failure ◽

Determining Factor

Resistance training protocols performed to muscle failure (MF) have been employed in an attempt to maximize activation and neuromuscular fatigue. Therefore, the aim of this study was to compare the surface electromyography amplitude (EMGRMS) and frequency (EMGFREQ) of the pectoralis major between protocols performed to MF and non muscle failure (NMF). Seven trained men performed three sets at 60% of a repetition maximum, with a 3 min rest period and a 6s repetition duration. MF protocol was performing with maximum number of repetitions in all sets, while in NMF protocol subjects performed 6 repetitions in 3 sets. For data analysis two two-way repeated measures ANOVAs (Protocol x Repetition) were used and when necessary, Bonferroni post hoc was performed. The EMGRMS was higher in the protocol MF compare to NMF, but there was no difference in EMGFREQ between protocols. Although there were no significant differences in the frequency domain between protocols, perform repetitions to MF was a determining factor to generate higher amplitude of the electromyography signal. Thus, perform repetitions to MF could be considered an effective strategy to increase muscle activation in trained individuals, however, with similar neuromuscular fatigue.

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Reliability and Differences of Jump Kinetics Related to Different Load in College Male Athletes

Athens Journal of Sports ◽

10.30958/ajspo.8-4-3 ◽

2021 ◽

Vol 8 (4) ◽

pp. 261-270

Author(s):

Chia-Hung Chuang ◽

Ching-Hung Lin ◽

Cheng-Wen Wu ◽

Kuo-Chuan Lin

Keyword(s):

Repeated Measures ◽

Force Plate ◽

Eccentric Contraction ◽

Countermovement Jump ◽

Male Athletes ◽

Arm Swing ◽

Repetition Maximum ◽

College Male ◽

Contraction Duration ◽

Post Hoc

The purpose of this study was to explore reliability and differences of jump kinetics related to different training load in college male athletes. The subjects were required to perform countermovement jump (CMJ) and loaded countermovement jump (LCMJ-0%, LCMJ-20% and LCMJ-80% of one-repetition maximum squat) three times for each load which were recorded by a force plate. One-way repeated measures ANOVA and the LSD post hoc method were employed to evaluate the results. The results reveled that jump kinetics-related parameters increased/decreased by the load. Compared with the loading jumps, the CMJ incorporate with an arm swing directly led to an increase in eccentric contraction duration during jumping. Most of the jump mechanical parameters under substantially different load conditions fall within the good to excellent reliability. It appears that the CMJ and CMJ with extra load were reliable in explore the kinetics related parameters. Keywords: countermovement jump, one-repetition maximum, arm swing, eccentric contraction

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Initial Evaluation of the LifeForce Yoga Program as a Therapeutic Intervention for Depression

International Journal of Yoga Therapy ◽

10.17761/ijyt.18.1.6x535022m2g37732 ◽

2008 ◽

Vol 18 (1) ◽

pp. 49-57 ◽

Cited By ~ 1

Author(s):

Shannon Bennett ◽

Amy Weintraub ◽

Sat Bir Khalsa

Keyword(s):

Repeated Measures ◽

Self Report ◽

Initial Training ◽

Home Practice ◽

Repeated Measures Anova ◽

Symptoms Of Depression ◽

Main Effect ◽

Symptom Scores ◽

Assessment Time ◽

Post Hoc

There is a growing body of literature citing Yoga as an effective intervention for decreasing symptoms of depression. This naturalistic pilot study investigated the efficacy of the LifeForce Yoga Program in decreasing reported symptoms of depression and other mood symptoms. The sample consisted of 94 individuals who completed self-report questionnaire before participating in a five-day LifeForce Yoga training. 54 of these individuals completed the same questionnaire after two weeks of home practice following the training, and 33 participants completed these questionnaires two months after the initial training. Repeated measures ANOVA tests demonstrated a main effect for time, indicating that mean symptom scores decreased significantly across the assessment time points on nearly all of the outcome measures of interest. Post hoc t-tests showed that the statistically significant change occurred between Time 1 and Time 2, and was then largely maintained from Time 2 to Time 3. These results suggest that participation in a comprehensive Yoga program, designed specifically to address mood, can lead to decreased symptoms of depression and associated physical or mood states.

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Effect of Sampling Frequency on Isometric Midthigh-Pull Kinetics

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2019-2015-0222 ◽

2019 ◽

Vol 14 (4) ◽

pp. 525-530 ◽

Cited By ~ 2

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.

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Performance of Physical Activities by Adolescents With Cerebral Palsy

Physical Therapy ◽

10.2522/ptj.20060089 ◽

2007 ◽

Vol 87 (1) ◽

pp. 77-87 ◽

Cited By ~ 48

Author(s):

Robert J Palisano ◽

Wendy P Copeland ◽

Barbara E Galuppi

Keyword(s):

Cerebral Palsy ◽

Repeated Measures ◽

Transition Planning ◽

Physical Therapist ◽

Physical Activities ◽

Time Interaction ◽

Repeated Measures Analysis ◽

Main Effect ◽

Post Hoc ◽

Gmfcs Level

Background and Purpose Mobility and self-care are important considerations for successful transition of adolescents with cerebral palsy to adulthood. The purpose of this study was to characterize performance of physical activities from the perspective of adolescents themselves. Subjects The subjects were 156 adolescents with cerebral palsy, 11.6 to 17.7 years of age. Methods A therapist completed the Gross Motor Function Classification System (GMFCS). Adolescents completed the Activities Scale for Kids–Performance Version (ASKp) twice over a 1-year period. Results A repeated-measures analysis of variance indicated a main effect for GMFCS level. The main effect for time and the GMFCS level × time interaction were not significant. Post hoc comparisons indicated that ASKp scores differed among all GMFCS levels. Discussion and Conclusion Performance of physical activities by adolescents with cerebral palsy differed based on GMFCS level and did not change over 1 year. The ASKp scores of adolescents in levels II through V suggest the need for physical assistance at times throughout the day. The results have implications for the role of the physical therapist in transition planning.

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A Comparison of Peak Intensity Periods across Male Field Hockey Competitive Standards

Sports ◽

10.3390/sports9050058 ◽

2021 ◽

Vol 9 (5) ◽

pp. 58

Author(s):

Eoin Cunniffe ◽

Adam Grainger ◽

Walter McConnell ◽

Ulrik McCarthy Persson ◽

Eamonn Delahunt ◽

...

Keyword(s):

Effect Sizes ◽

Field Hockey ◽

Match Play ◽

Total Distance ◽

Peak Intensity ◽

Hockey Players ◽

Competition Level ◽

Main Effect ◽

Significance Levels ◽

Post Hoc

This investigation aimed to compare the international level peak intensity period of male field hockey players to those experienced during professional and amateur club hockey match play. Twenty-seven players from an international squad were monitored for all activity relating to field hockey over three seasons. The peak intensity period, of 3 min duration, was extracted from match play files for international and club matches. Club matches were categorised by league standard—professional vs. amateur. The output for the peak intensity period, within positions, was compared using linear mixed models (LMMs) and post hoc pairwise comparisons. Significance levels were set as p < 0.05 and Cohen’s d was utilised for effect sizes. Competition level had a main effect on relative total distance (p < 0.05) and significant interaction effects were found between competition level and position (p < 0.05). Midfielders competing in amateur leagues and international match play completed less relative total distance than those who compete in professional leagues (−47.88 m/min, p < 0.05), (−46.06 m/min, p < 0.05) with large effect sizes reported. No other position displayed significant differences for peak periods. Match play in professional leagues provide opportunities for midfielders to experience peak intensity periods of a greater magnitude than international match play.

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Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase

Journal of Human Kinetics ◽

10.1515/hukin-2015-0042 ◽

2015 ◽

Vol 46 (1) ◽

pp. 139-148 ◽

Cited By ~ 14

Author(s):

María Asunción Martínez-Valencia ◽

Salvador Romero-Arenas ◽

José L.L. Elvira ◽

José María González-Ravé ◽

Fernando Navarro-Valdivielso ◽

...

Keyword(s):

Repeated Measures ◽

Training Stimulus ◽

Force Production ◽

Sprint Performance ◽

Peak Force ◽

Rate Of Force Development ◽

Sprint Training ◽

Force Output ◽

Acceleration Phase ◽

Force Development

AbstractResisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm)) on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg) performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak), a peak rate of force development (RFDpeak) and time to RFD (TRFD) in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001) in sprint times (20 and 30 m sprint) for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s−1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s−1, p ≤ 0.01). Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration.

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Effect of Sampling Frequency on Isometric Midthigh-Pull Kinetics

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2015-0222 ◽

2016 ◽

Vol 11 (2) ◽

pp. 255-260 ◽

Cited By ~ 20

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.

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Differences in Kinetics during One- and Two-Leg Hang Power Clean

Sports ◽

10.3390/sports9040045 ◽

2021 ◽

Vol 9 (4) ◽

pp. 45

Author(s):

Ryohei Hayashi ◽

Takuya Yoshida ◽

Yasushi Kariyama

Keyword(s):

Peak Power ◽

Peak Force ◽

Time Data ◽

Repetition Maximum ◽

Force Development ◽

Power Peak ◽

Explosive Force ◽

Force Time ◽

The One ◽

Power Clean

The purpose of this study was to quantify the kinetics per leg during the one- and two-leg hang power clean using various loads. Nine male track and field athletes performed the one- and two-leg hang power clean on a force platform. The estimated one-repetition maximum was used for the one-leg hang power clean (OHPC), and the one-repetition maximum was used for the two-leg hang power clean (THPC). The loads used were 30%, 60%, and 90% during both trials. We calculated peak power, peak force, and peak rate of force development during the pull phase from the force-time data. The peak power and the peak force for all loads during the OHPC were statistically greater than during the THPC. The peak rates of force development at 60% and 90% during the OHPC were statistically greater than during the THPC. Additionally, the peak power at 90% was significantly less than at 60% during the THPC. These findings suggest that the OHPC at loads of 60% and 90% is a weightlifting exercise that exhibits greater explosive force and power development characteristics than the THPC.

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