Power attenuation from restricting range of motion is minimized in subjects with fast RTD and following isometric training

Time-dependent measures consisting of rate of torque development (RTD), rate of velocity development (RVD), and rate of neuromuscular activation can be used to evaluate explosive muscular performance, which becomes critical when performing movements throughout limited ranges of motion (ROM). Using a HUMAC NORM dynamometer, seven males (27 ± 7 years) and six females (22 ± 3 years) underwent 8 weeks of maximal isometric dorsiflexion training 3 days/week. One leg was trained at 0° (short-muscle tendon unit (MTU) length) and the other at 40° of plantar flexion (long-MTU length). RTD and rate of neuromuscular activation were evaluated during 'fast' maximal isometric contractions. Power, RVD, and rate of neuromuscular activation were assessed during maximal isotonic contractions in four conditions (small (40° to 30° of plantar flexion) ROM at 10 and 50% MVC; large (40° to 0° of plantar flexion) ROM at 10 and 50% MVC) for both legs, pre- and post-training. Despite no change in rate of neuromuscular activation following training, peak power, RTD, and RVD increased at both MTU lengths (p < 0.05). Strong relationships (R2=0.73) were observed between RTD and peak power in the small ROM, indicating that fast time-dependent measures are critical for optimal performance when ROM is constrained. Meanwhile, strong relationships (R2=0.90) between RVD and power were observed at the 50% load, indicating that RVD is critical when limited by load and ROM is not confined. Maximal isometric dorsiflexion training can be used to improve time-dependent measures (RTD, RVD) to minimize power attenuation when ROM is restricted.

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Influence of sex on performance fatigability of the plantar flexors following repeated maximal dynamic shortening contractions

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2017-0013 ◽

2017 ◽

Vol 42 (10) ◽

pp. 1118-1121 ◽

Cited By ~ 4

Author(s):

Amelia C. Lanning ◽

Geoffrey A. Power ◽

Anita D. Christie ◽

Brian H. Dalton

Keyword(s):

Sex Differences ◽

Development Rate ◽

Time Dependent ◽

Plantar Flexors ◽

Neuromuscular Activation ◽

Rate Of Torque Development ◽

Torque Development ◽

Shortening Contractions

The purpose was to determine sex differences in fatigability during maximal, unconstrained velocity, shortening plantar flexions. The role of time-dependent measures (i.e., rate of torque development, rate of velocity development, and rate of neuromuscular activation) in such sex-related differences was also examined. By task termination, females exhibited smaller reductions in power and similar changes in rate of neuromuscular activation than males, indicating females were less fatigable than males.

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Isometric and dynamic strength and neuromuscular attributes as predictors of vertical jump performance in 11- to 13-year-old male athletes

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2017-0111 ◽

2017 ◽

Vol 42 (9) ◽

pp. 924-930 ◽

Cited By ~ 4

Author(s):

Brandon John McKinlay ◽

Phillip J. Wallace ◽

Raffy Dotan ◽

Devon Long ◽

Craig Tokuno ◽

...

Keyword(s):

Vastus Lateralis ◽

Peak Torque ◽

Soccer Players ◽

Neural Activation ◽

Male Athletes ◽

Neuromuscular Activation ◽

Jump Performance ◽

Rate Of Torque Development ◽

Dynamic Contractions ◽

Torque Development

In explosive contractions, neural activation is a major factor in determining the rate of torque development, while the latter is an important determinant of jump performance. However, the contribution of neuromuscular activation and rate of torque development to jump performance in children and youth is unclear. The purpose of this study was to examine the relationships between the rate of neuromuscular activation, peak torque, rate of torque development, and jump performance in young male athletes. Forty-one 12.5 ± 0.5-year-old male soccer players completed explosive, unilateral isometric and dynamic (240°/s) knee extensions (Biodex System III), as well as countermovement-, squat-, and drop-jumps. Peak torque (pT), peak rate of torque development (pRTD), and rate of vastus lateralis activation (Q30) during the isometric and dynamic contractions were examined in relation to attained jump heights. Isometric pT and pRTD were strongly correlated (r = 0.71) but not related to jump performance. Dynamic pT and pRTD, normalized to body mass, were significantly related to jump height in all 3 jumps (r = 0.38–0.66, p < 0.05). Dynamic normalized, but not absolute pRTD, was significantly related to Q30 (r = 0.35, p < 0.05). In young soccer players, neuromuscular activation and rate of torque development in dynamic contractions are related to jump performance, while isometric contractions are not. These findings have implications in the choice of training and assessment methods for young athletes.

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The number of sessions required to stabilize peak torque and rate of torque development in isometric contractions in young, middle-age and older individuals

Isokinetics and Exercise Science ◽

10.3233/ies-160627 ◽

2016 ◽

Vol 24 (2) ◽

pp. 165-170

Author(s):

Cleiton Augusto Libardi ◽

Thiago Mattos Frota Souza ◽

Miguel Soares Conceição ◽

Mara Patricia Traina Chacon-Mikahil ◽

Carlos Ugrinowitsch ◽

...

Keyword(s):

Middle Age ◽

Peak Torque ◽

Isometric Contractions ◽

Older Individuals ◽

Rate Of Torque Development ◽

Torque Development

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Discriminatory Ability of Lower-Extremity Peak Torque and Rate of Torque Development in the Identification of Older Women With Slow Gait Speed

Journal of Applied Biomechanics ◽

10.1123/jab.2016-0354 ◽

2018 ◽

Vol 34 (4) ◽

pp. 270-277 ◽

Cited By ~ 1

Author(s):

Mary Hellen Morcelli ◽

Dain Patrick LaRoche ◽

Luciano Fernandes Crozara ◽

Nise Ribeiro Marques ◽

Camilla Zamfolini Hallal ◽

...

Keyword(s):

Older Women ◽

Gait Speed ◽

Plantar Flexion ◽

Peak Torque ◽

Knee Extension ◽

Muscle Group ◽

Rate Of Torque Development ◽

Functional Gait ◽

Hip Extension ◽

Torque Development

The aim was to compare torque and rate of torque development of lower limb muscles between older women with functional and slow gait speeds to determine which muscle group is the best predictor of functional gait speed, and to establish strength thresholds needed for functional walking speed. Torque and rate of torque development of hip, knee, and ankle muscles were measured in older women who were divided in 2 groups according to gait speed: slow gait speed (<1.22 m·s−1) and functional gait speed (≥1.22 m·s−1). For each muscle group, 3 maximal isometric contractions were performed, and peak torque and rate of torque development were recorded. Older women with slow gait speed had lower peak torque than older women with functional gait speed for hip extension (28%), knee flexion (15%), knee extension (14%), and plantar flexion (16%) (allPs < .05). Older women with slow gait speed had lower peak rate of torque development for hip flexion (29%), hip extension (37%), knee flexion (34%), knee extension (33%), and plantar flexion (19%) (allPs < .05). Knee extension peak rate of torque development and hip extension peak torque were the better predictors of functional gait speed with thresholds of 2.96 N·m·s−1·kg−1and 1.26 N·m·kg−1, respectively.

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Peak power is reduced following lengthening contractions despite a maintenance of shortening velocity

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2013-0092 ◽

2013 ◽

Vol 38 (12) ◽

pp. 1196-1205 ◽

Cited By ~ 10

Author(s):

Geoffrey A. Power ◽

Brian H. Dalton ◽

Charles L. Rice ◽

Anthony A. Vandervoort

Keyword(s):

Peak Power ◽

Recovery Period ◽

Shortening Velocity ◽

Lengthening Contractions ◽

Maximum Voluntary Isometric Contraction ◽

Relative Contribution ◽

Rate Of Torque Development ◽

Isometric Torque ◽

Torque Development ◽

Shortening Contractions

Following repetitive lengthening contractions, power (the product of torque and velocity) is impaired during shortening contractions. However, the relative contribution of each component to power loss and the underlying factors are unclear. We investigated neuromuscular properties of the dorsiflexors in 8 males (27 ± 3 years) and 8 females (26 ± 4 years) for a potential sex-related difference before, during, and after 150 unaccustomed maximal lengthening actions. Velocity-dependent power was determined from shortening contractions at 8 levels (1 N·m to 70% of maximum voluntary isometric contraction (MVC)) before, after, and throughout recovery assessed at 0–30 min, 24 h, and 48 h. Immediately following task termination, both sexes displayed similar impairments of 30%, 4%, and 10% in MVC torque, shortening velocity, and overall peak power, respectively (P < 0.05). Peak rate of isometric torque development (RTD) was reduced by 10% in males, but females exhibited a 35% reduction (P < 0.05). Rate of torque development for the MVC remained depressed in both sexes throughout the 30 min recovery period; however, the RTD returned to normal by 24 h in males but did not recover by 48 h in females. Power was reduced preferentially at higher loads (i.e., 60% MVC), with a greater loss in females (65%) than males (45%). For lower loads (<20% MVC), power was impaired minimally (4%–8%; P < 0.05) and recovered within 30 min in both groups. The reduction in maximal angular velocity persisted until 30 min of recovery, and peak power did not recover until 24 h for both sexes. Unaccustomed lengthening contractions decreased power preferentially at higher loads, whereas peak power was reduced minimally owing to maintenance of maximal shortening velocity.

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Test–Retest Reliability of Plantar Flexion Torque Generation During a Functional Knee Extended Position in Older and Younger Men

Journal of Aging and Physical Activity ◽

10.1123/japa.2020-0288 ◽

2020 ◽

pp. 1-6

Author(s):

Lucas Ugliara ◽

James J. Tufano ◽

Martim Bottaro ◽

Amilton Vieira

Keyword(s):

Correlation Coefficient ◽

Intraclass Correlation Coefficient ◽

Plantar Flexion ◽

Intraclass Correlation ◽

Older Men ◽

Retest Reliability ◽

Rate Of Torque Development ◽

Younger Men ◽

Test Retest Reliability ◽

Torque Development

Measuring ankle torque is of paramount importance. This study compared the test–retest reliability of the plantar flexion torque–generating capacity between older and younger men. Twenty-one older (68 ± 6 years) and 22 younger (25 ± 5 years) men were tested twice for maximal isometric plantar flexion. Peak torque (PT), rate of torque development, and contractile impulses (CI) were obtained from 0 to 50 ms (rate of torque development0–50; CI0–50) and from 100 to 200 ms (rate of torque development100–200; CI100–200). Typical error as the coefficient of variation (CVTE) and intraclass correlation coefficient were used to assess test–retest reliability. Student’s t test was applied to investigate systematic errors. The CVTE ratio was used for between-group comparisons. Only PT demonstrated acceptable reliability (intraclass correlation coefficient ≥ .75 and CV ≤ 10%). Older men demonstrated greater CVTE than younger men for PT (ratio = 2.24), but lesser for rapid torque (ratio ≤ 0.84). Younger men demonstrated systematic error for PT (6.5%) and CI100–200 (−8.9%). In conclusion, older men demonstrated greater variability for maximal torque output, but lesser for rapid torque.

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Peak torque, rate of torque development and average torque of isometric ankle and elbow contractions show excellent test–retest reliability

Hong Kong Physiotherapy Journal ◽

10.1142/s1013702519500069 ◽

2019 ◽

Vol 39 (01) ◽

pp. 67-76

Author(s):

Daniel Simpson ◽

Monika Ehrensberger ◽

Christopher Nulty ◽

Joanne Regan ◽

Patrick Broderick ◽

...

Keyword(s):

Muscle Function ◽

Intraclass Correlation ◽

Peak Torque ◽

Testing Procedure ◽

Ankle Dorsiflexion ◽

Isometric Contractions ◽

Elbow Extension ◽

Rate Of Torque Development ◽

Test Retest Reliability ◽

Torque Development

Background: Peak Torque (PT), Rate of Torque Development (RTD) and Average Torque (AT) over a single contraction assess the three components of muscle function during isometric contractions. Surprisingly, AT has never been reported or its reliability confirmed.Objectives: This study aims to establish protocol reliability for ankle dorsiflexion and elbow extension isometric muscle function (PT, RTD, AT) in healthy participants using the Biodex System 3 Dynamometer.Methods: Twelve participants (6 male, 6 female, mean age [Formula: see text] years) performed four maximal isometric contractions on two occasions. Intraclass Correlation Coefficient (ICC), Typical Error (TE) and Coefficient of Variation (CV) for PT, RTD and AT were reported.Results: The ICC for all strength parameters varied from 0.98–0.92. TE for ankle dorsiflexion PT was 1.38[Formula: see text]Nm, RTD 7.43[Formula: see text]Nm/s and AT 1.33[Formula: see text]Nm, CV varied from [Formula: see text] to [Formula: see text]. For elbow extension, TE was 3.36[Formula: see text]Nm for PT, 14.87[Formula: see text]Nm/s for RTD and 3.03[Formula: see text]Nm for AT, CV varied from [Formula: see text] to [Formula: see text].Conclusion: Maximal isometric ankle dorsiflexion and elbow extension PT, RTD and AT can be evaluated with excellent reliability when following the described protocol. This testing procedure, including the application of AT, can be confidently applied in research, exercise or clinical settings.

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Postactivation Potentiation Biases Maximal Isometric Strength Assessment

BioMed Research International ◽

10.1155/2014/126961 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 6

Author(s):

Leonardo Coelho Rabello Lima ◽

Felipe Bruno Dias Oliveira ◽

Thiago Pires Oliveira ◽

Claudio de Oliveira Assumpção ◽

Camila Coelho Greco ◽

...

Keyword(s):

Force Production ◽

Peak Torque ◽

Isometric Strength ◽

Isometric Contractions ◽

Postactivation Potentiation ◽

Healthy Male ◽

Strength Assessment ◽

Rate Of Torque Development ◽

Electromyographic Signal ◽

Torque Development

Postactivation potentiation (PAP) is known to enhance force production. Maximal isometric strength assessment protocols usually consist of two or more maximal voluntary isometric contractions (MVCs). The objective of this study was to determine if PAP would influence isometric strength assessment. Healthy male volunteers (n=23) performed two five-second MVCs separated by a 180-seconds interval. Changes in isometric peak torque (IPT), time to achieve it (tPTI), contractile impulse (CI), root mean square of the electromyographic signal during PTI (RMS), and rate of torque development (RTD), in different intervals, were measured. Significant increases in IPT (240.6 ± 55.7 N·mversus248.9 ± 55.1 N·m), RTD (746 ± 152 N·m·s−1versus727 ± 158 N·m·s−1), and RMS (59.1 ± 12.2%RMSMAX versus54.8 ± 9.4%RMSMAX) were found on the second MVC. tPTI decreased significantly on the second MVC (2373 ± 1200 msversus2784 ± 1226 ms). We conclude that a first MVC leads to PAP that elicits significant enhancements in strength-related variables of a second MVC performed 180 seconds later. If disconsidered, this phenomenon might bias maximal isometric strength assessment, overestimating some of these variables.

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