Movement-Related Cortical Potentials Allow Discrimination of Rate of Torque Development in Imaginary Isometric Plantar Flexion

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

Journal of Applied Physiology ◽

10.1152/japplphysiol.00688.2021 ◽

2022 ◽

Author(s):

Brooke Davidson ◽

Avery Hinks ◽

Brian H. Dalton ◽

Ryota Akagi ◽

Geoffrey A. Power

Keyword(s):

Peak Power ◽

Plantar Flexion ◽

Time Dependent ◽

Isometric Contractions ◽

Fast Time ◽

Neuromuscular Activation ◽

Rate Of Torque Development ◽

Isotonic Contractions ◽

Torque Development ◽

Strong Relationships

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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Rate of Torque Development and Voluntary Quadriceps Activation in Patients With Knee Osteoarthritis: A Quantitative Analysis Before and After a Single Session of Manual Physical Therapy

Case Medical Research ◽

10.31525/ct1-nct04234282 ◽

2020 ◽

Author(s):

Keyword(s):

Quantitative Analysis ◽

Physical Therapy ◽

Knee Osteoarthritis ◽

Single Session ◽

Rate Of Torque Development ◽

Before And After ◽

Torque Development

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Knee flexor strength, rate of torque development and flexibility in women and men with patellofemoral pain: Relationship with pain and the single leg bridge test

Physical Therapy in Sport ◽

10.1016/j.ptsp.2021.05.006 ◽

2021 ◽

Author(s):

Matheus Henrique Maiolini Ducatti ◽

Marina Cabral Waiteman ◽

Ana Flávia Balotari Botta ◽

Helder dos Santos Lopes ◽

Neal Robert Glaviano ◽

...

Keyword(s):

Patellofemoral Pain ◽

Knee Flexor ◽

Rate Of Torque Development ◽

Torque Development ◽

Flexor Strength

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Blockade of 5-HT2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions

Journal of Neurophysiology ◽

10.1152/jn.00470.2021 ◽

2021 ◽

Author(s):

Benjamin Ian Goodlich ◽

Sean A Horan ◽

Justin J Kavanagh

Keyword(s):

Motor Unit ◽

Unit Activity ◽

Repeated Measures ◽

Discharge Rate ◽

Voluntary Contraction ◽

Unit Discharge ◽

Motor Unit Activity ◽

Rate Of Torque Development ◽

Motor Unit Discharge ◽

Torque Development

Serotonin (5-HT) is a neuromodulator that is critical for regulating the excitability of spinal motoneurons and the generation of muscle torque. However, the role of 5-HT in modulating human motor unit activity during rapid contractions has yet to be assessed. Nine healthy participants (23.7 ± 2.2 yr) ingested 8 mg of the competitive 5-HT2 antagonist cyproheptadine in a double-blinded, placebo-controlled, repeated-measures experiment. Rapid dorsiflexion contractions were performed at 30%, 50% and 70% of maximal voluntary contraction (MVC), where motor unit activity was assessed by high-density surface electromyographic decomposition. A second protocol was performed where a sustained, fatigue-inducing dorsiflexion contraction was completed prior to undertaking the same 30%, 50% and 70% MVC rapid contractions and motor unit analysis. Motor unit discharge rate (p < 0.001) and rate of torque development (RTD; p = 0.019) for the unfatigued muscle were both significantly lower for the cyproheptadine condition. Following the fatigue inducing contraction, cyproheptadine reduced motor unit discharge rate (p < 0.001) and RTD (p = 0.024), where the effects of cyproheptadine on motor unit discharge rate and RTD increased with increasing contraction intensity. Overall, these results support the viewpoint that serotonergic effects in the central nervous system occur fast enough to regulate motor unit discharge rate during rapid powerful contractions.

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