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

2017 ◽  
Vol 42 (10) ◽  
pp. 1118-1121 ◽  
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.

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

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.

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

2017 ◽  
Vol 42 (9) ◽  
pp. 924-930 ◽  
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.

scholarly journals Sex Differences In Quadriceps Strength And Rate Of Torque Development 6 Months Post ACL Reconstruction

2020 ◽  
Vol 52 (7S) ◽  
pp. 796-796
Author(s):  
Victor Huynh ◽  
Joshua J. Van Wyngaarden ◽  
Kathryn Lucas ◽  
Darren Johnson ◽  
Mary L. Ireland ◽  
...  
Keyword(s):  
Sex Differences ◽  
Acl Reconstruction ◽  
Quadriceps Strength ◽  
Rate Of Torque Development ◽  
Torque Development

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

2013 ◽  
Vol 38 (12) ◽  
pp. 1196-1205 ◽  
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.

Sex differences in quadriceps rate of torque development within 1 year of ACL reconstruction

2019 ◽  
Vol 38 ◽  
pp. 36-43 ◽  
Author(s):  
Christopher Kuenze ◽  
Caroline Lisee ◽  
Thomas Birchmeier ◽  
Ashley Triplett ◽  
Luke Wilcox ◽  
...  
Keyword(s):  
Sex Differences ◽  
Acl Reconstruction ◽  
Rate Of Torque Development ◽  
Torque Development

Intersexual and Intrasexual Competition and Their Relation to Jealousy

2019 ◽  
pp. 214-236
Author(s):  
Abraham P. Buunk ◽  
Karlijn Massar ◽  
Pieternel Dijkstra ◽  
Ana María Fernández
Keyword(s):  
Sex Differences ◽  
Individual Differences ◽  
Menstrual Cycle ◽  
Attachment Styles ◽  
Mate Guarding ◽  
Intrasexual Competition ◽  
Online Infidelity ◽  
Intersexual Competition

This chapter discusses sex differences in intersexual competition and describes particularly the consequences of such competition for conflict between the sexes, as well as for sex differences in mate guarding and, relatedly, in the types of infidelity that evoke jealousy, including online infidelity. It also discusses individual differences in jealousy as related to attachment styles and describes the effects of height, hormones, and the menstrual cycle on jealousy. Next, the chapter moves on to intrasexual competition and discusses, among other topics, intrasexual competition among men and among women, the role of sex differences in rival characteristics in evoking jealousy, the role of attachment styles and hormones, and individual differences in intrasexual competitiveness.

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