scholarly journals The single-leg heel raise does not predict maximal plantar flexion strength in healthy males and females

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0253276
Author(s):  
Lauren K. Sara ◽  
Savannah B. Gutsch ◽  
Sandra K. Hunter
Keyword(s):  
Sex Differences ◽  
Plantar Flexion ◽  
Voluntary Activation ◽  
Plantar Flexor ◽  
Maximal Strength ◽  
Flexor Muscles ◽  
Males And Females ◽  
Flexion Strength ◽  
Plantar Flexor Muscles ◽  
Flexor Strength

Introduction The single-leg heel raise test (SLHR) is commonly used in clinical settings to approximate plantar flexor strength, yet this is neither validated nor supported physiologically. The purposes of this study were to: determine (1) associations between SLHR repetitions, maximal plantar flexor strength, and reductions in strength; and (2) whether sex differences exist in performance of the SLHR. Methods Twenty-eight young, healthy participants (14 males,14 females, 19–30 years) performed repeated single-leg heel raises to task failure. Pre- and post-task measures included maximal voluntary isometric contractions (MVIC), and voluntary activation and contractile properties of the plantar flexor muscles, assessed using peripheral electrical stimulation of the tibial nerve. Surface electromyography was recorded for the medial and lateral gastrocnemius, soleus, and anterior tibialis muscles. Results The SLHR resulted in 20.5% reductions in MVIC torque (p<0.001). However, the number of SLHR repetitions was not correlated with either the baseline MVIC (maximal strength; p = 0.979) or the reduction in MVIC following the SLHR (p = 0.23). There were no sex differences in either the number of SLHR repetitions (p = 0.14), baseline MVIC torque (p = 0.198), or the reduction of MVIC (p = 0.14). MVIC decline was positively associated with the reduction in voluntary activation (r = 0.841, p<0.001), but was not associated with the change in twitch amplitude (p = 0.597). Conclusions The SLHR was similar in young males and females yet was a poor predictor of maximal plantar flexor strength but evaluates performance fatigability of the lower extremity specific to dynamic contractions. The reduction in maximal strength at task failure was explained by reduced neural drive to the plantar flexor muscles in both males and females. Impact statement SLHR performance is not a clinical assessment of plantar flexor strength but assesses dynamic lower extremity fatigability that is similar in males and females. Alternate clinical measures for maximal plantar flexion strength need to be developed.

scholarly journals Stretching combined with repetitive small length changes of the plantar flexor muscles enhances their passive extensibility for longer duration than conventional static stretching, while not compromising strength

2018 ◽  
Author(s):  
Naoki Ikeda ◽  
Takayuki Inami ◽  
Yasuo Kawakami
Keyword(s):  
Range Of Motion ◽  
Plantar Flexion ◽  
Plantar Flexor ◽  
Static Stretching ◽  
Small Length ◽  
Local Vibration ◽  
Flexor Muscles ◽  
Length Changes ◽  
Flexion Strength ◽  
Plantar Flexor Muscles

AbstractStatic stretching increases flexibility but can decrease muscle strength, and the method to avoid the latter has been longed for. In this study, a novel stretching modality was developed that provides repetitive small length changes to the plantar flexor muscles undergoing passive static stretching (“local vibration stretching,”). We investigated the effects of local vibration stretching on muscle strength, flexibility and its persistence. Plantar flexion strength and maximal ankle joint dorsiflexion angle (dorsiflexion range of motion) were measured for 10 healthy young males before (pre) and immediately after (post) three types of stretching: static stretching, local vibration stretching at 15 Hz, and no intervention (control). The dorsiflexion range of motion was measured also at 15, 30, and 60 min post-stretching. Elongation of the medial gastrocnemius and Achilles tendon was determined by ultrasonography. Plantar flexion strength significantly decreased by 4.3 ± 3.5 % in static stretching but not in local vibration stretching. The dorsiflexion range of motion significantly increased both in static stretching (7.2 ± 8.1 %) and local vibration stretching (11.2 ± 14.6 %) which was accompanied by a significantly larger muscle elongation but not tendon elongation. Elevated dorsiflexion range of motion was maintained until 30 min after the local vibration stretching while it returned to baseline level (pre-intervention) in 15 min after the static stretching. All variables remained unchanged in the control condition. In conclusion, local vibration stretching improves extensibility of the muscle belly without decreasing strength, and the increased flexibility is retained longer than static stretching.

scholarly journals Sex differences in central and peripheral fatigue induced by sustained isometric ankle plantar flexion

2021 ◽  
Author(s):  
Donguk Jo ◽  
Miriam Goubran ◽  
Martin Bilodeau
Keyword(s):  
Sex Differences ◽  
Plantar Flexion ◽  
Recovery Period ◽  
Isometric Exercise ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Plantar Flexors ◽  
Maximal Voluntary Isometric Contraction ◽  
Males And Females

The main aim of this study was to determine sex differences in central and peripheral fatigue produced by a sustained isometric exercise of ankle plantar flexors in healthy young adults. Ten males and fourteen females performed a sustained isometric ankle exercise until task failure. Maximal voluntary isometric contraction torque (plantarflexion), voluntary activation level (using the twitch interpolation technique), and twitch contractile properties (twitch peak torque, twitch half relaxation time, and low frequency fatigue index) were measured before, immediately after, and throughout a recovery period (1, 2, 5, and 10 min) following the exercise protocol in order to characterize neuromuscular fatigue. Fatigue had a significant effect (p £ 0.05) on all dependent variables. Other than for the maximal voluntary contraction torque, where males showed a greater fatigue-related decrease than females, males and females showed generally similar changes with fatigue. Altogether, our findings indicate no major differences in central or peripheral fatigue mechanisms between males and females to explain a somewhat greater fatigability in males.

Robotic Shoe: An Ankle Assistive Device for Gait Plantar Flexion Assistance

2020 ◽  
Author(s):  
Marcus Schaller ◽  
Seyed Mostafa Rezayat Sorkhabadi ◽  
Wenlong Zhang
Keyword(s):  
Neurological Disorders ◽  
Plantar Flexion ◽  
Muscular Activity ◽  
Assistive Device ◽  
Walking Ability ◽  
Constant Force ◽  
Plantar Flexor ◽  
Ankle Foot Orthoses ◽  
Flexor Muscles ◽  
Plantar Flexor Muscles

Abstract Gait disorders can be attributed to a variety of factors including aging, injury, and neurological disorders. A common disorder involves the ankle push-off phase of an individual’s gait, which is vital to their ability to walk and propel themselves forward. During the ankle push-off stage, plantar flexor muscles are required to provide a large amount of torque to propel the heel off the ground, thus a condition that compromises the strength of these muscles can greatly affect one’s walking ability. In order to rectify these issues, Ankle-Foot Orthoses (AFO) are used to provide support to a user’s ankle and assist with the force needed for heel off. This article introduces a robotic AFO which was developed with the intent of aiding during the heel-off stage. The proposed design utilizes the user’s body weight to extend constant force springs positioned parallel to the calf to replicate the muscular force generated in plantar flexion. The extended spring is held in place using a ratcheting mechanism which is released with a solenoid during heel up. Similar research has been conducted in which assistive AFO’s have been created, however little research has investigated the use of constant force springs in such devices. A healthy user tested the device on a treadmill and surface electromyography (sEMG) sensors were placed on the user’s plantar flexor muscles to monitor potential reductions in muscular activity resulting from the assistance provided by the AFO device. The data demonstrates the robotic shoe was able to assist during the heel-off stage and reduced activation in the plantar flexor muscles was evident from the EMG data collected.

scholarly journals Activation of human plantar flexor muscles increases after electromyostimulation training

2002 ◽  
Vol 92 (4) ◽  
pp. 1383-1392 ◽  
Author(s):  
Nicola A. Maffiuletti ◽  
Manuela Pensini ◽  
Alain Martin
Keyword(s):  
Voluntary Activation ◽  
Emg Activity ◽  
Control Group ◽  
Neural Activation ◽  
Plantar Flexor ◽  
Postactivation Potentiation ◽  
Short Term ◽  
Flexor Muscles ◽  
Electrically Evoked Contractions ◽  
Plantar Flexor Muscles

Neuromuscular adaptations of the plantar flexor muscles were assessed before and subsequent to short-term electromyostimulation (EMS) training. Eight subjects underwent 16 sessions of isometric EMS training over 4 wk. Surface electromyographic (EMG) activity and torque obtained under maximal voluntary and electrically evoked contractions were analyzed to distinguish neural adaptations from contractile changes. After training, plantar flexor voluntary torque significantly increased under isometric conditions at the training angle (+8.1%, P< 0.05) and at the two eccentric velocities considered (+10.8 and +13.1%, P < 0.05). Torque gains were accompanied by higher normalized soleus EMG activity and, in the case of eccentric contractions, also by higher gastrocnemii EMG ( P < 0.05). There was an 11.9% significant increase in both plantar flexor maximal voluntary activation ( P < 0.01) and postactivation potentiation ( P < 0.05), whereas contractile properties did not change after training. In the absence of a change in the control group, it was concluded that an increase in neural activation likely mediates the voluntary torque gains observed after short-term EMS training.

scholarly journals Ultrasound-derived changes in thickness of human ankle plantar flexor muscles during walking and running are not homogeneous along the muscle mid-belly region

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. F. Hodson-Tole ◽  
A. K. M. Lai
Keyword(s):  
Statistical Parametric Mapping ◽  
Muscle Thickness ◽  
Ultrasound Images ◽  
Plantar Flexor ◽  
Image Region ◽  
Thickness Change ◽  
Musculoskeletal Models ◽  
Flexor Muscles ◽  
Anatomical Space ◽  
Plantar Flexor Muscles

Abstract Skeletal muscle thickness is a valuable indicator of several aspects of a muscle’s functional capabilities. We used computational analysis of ultrasound images, recorded from 10 humans walking and running at a range of speeds (0.7–5.0 m s−1), to quantify interactions in thickness change between three ankle plantar flexor muscles (soleus, medial and lateral gastrocnemius) and quantify thickness changes at multiple muscle sites within each image. Statistical analysis of thickness change as a function of stride cycle (1d statistical parametric mapping) revealed significant differences between soleus and both gastrocnemii across the whole stride cycle as they bulged within the shared anatomical space. Within each muscle, changes in thickness differed between measurement sites but not locomotor condition. For some of the stride, thickness measures taken from the distal-mid image region represented the mean muscle thickness, which may therefore be a reliable region for these measures. Assumptions that muscle thickness is constant during a task, often made in musculoskeletal models, do not hold for the muscles and locomotor conditions studied here and researchers should not assume that a single thickness measure, from one point of the stride cycle or a static image, represents muscle thickness during dynamic movements.

Characterization of torque generating properties of ankle plantar flexor muscles in ambulant adults with cerebral palsy

2019 ◽  
Vol 119 (5) ◽  
pp. 1127-1136 ◽  
Author(s):  
Rasmus Feld Frisk ◽  
Jakob Lorentzen ◽  
Lee Barber ◽  
Jens Bo Nielsen
Keyword(s):  
Cerebral Palsy ◽  
Plantar Flexor ◽  
Flexor Muscles ◽  
Plantar Flexor Muscles

Chronic effects of muscle and nerve-directed stretching on tissue mechanics

2020 ◽  
Vol 129 (5) ◽  
pp. 1011-1023 ◽  
Author(s):  
Ricardo J. Andrade ◽  
Sandro R. Freitas ◽  
François Hug ◽  
Guillaume Le Sant ◽  
Lilian Lacourpaille ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Sciatic Nerve ◽  
Peripheral Nerves ◽  
Tissue Mechanics ◽  
Plantar Flexor ◽  
Chronic Effects ◽  
Flexor Muscles ◽  
Plantar Flexor Muscles

This study demonstrates that the mechanical properties of plantar flexor muscles and sciatic nerve can adapt mechanically to long-term stretching programs. Although interventions targeting muscular or nonmuscular structures are both effective at increasing maximal range of motion, the changes in tissue mechanical properties (stiffness) are specific to the structure being preferentially stretched by each program. We provide the first in vivo evidence that stiffness of peripheral nerves adapts to long-term loading stimuli using appropriate nerve-directed stretching.

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