Poststretch Isometric Contractions of the Hamstrings: Just a Brief Stretch to Achieve Supramaximal Isometric Force

2021 ◽  
pp. 1-7
Author(s):  
Neil Chapman ◽  
John William Whitting ◽  
Suzanne Broadbent ◽  
Zachary Crowley-McHattan ◽  
Rudi Meir
Keyword(s):  
Isometric Contraction ◽  
Knee Flexion ◽  
Isometric Force ◽  
Biceps Femoris ◽  
Isometric Contractions ◽  
Maximal Voluntary Isometric Contraction ◽  
Hamstring Strain ◽  
Long Head ◽  
Biceps Femoris Long Head ◽  
Knee Flexors

Hamstring strain injuries are common in sport. Supramaximal eccentric or high-intensity isometric contractions are favored in hamstring strain injury prevention. The effect of combining these contraction modes in such prevention programs as a poststretch isometric contraction is unknown. Poststretch isometric contractions incorporate an active stretch and result in greater final isometric force than isometric contractions at comparable joint angles. This study compared torque and muscle activation levels between maximal voluntary isometric contraction and maximal poststretch isometric contractions of the knee flexors. Participants (n = 9) completed baseline maximal voluntary isometric contraction at 150° knee flexion and maximal poststretch isometric contractions at 120° knee flexion actively stretching at 60°/s to 150° knee flexion for final isometric contraction. Torque of the knee flexors and surface electromyography root mean square (sEMGRMS) of biceps femoris long head were simultaneously recorded and compared between baseline and poststretch isometric at 150° knee flexion. Torque was 14% greater in the poststretch isometric condition compared with baseline maximal voluntary isometric contraction (42.45 [20.75] N·m, 14% [22.18%], P < .001) without increase in sEMGRMS of biceps femoris long head (−.03 mV, ±.06, P = .130, d = .93). Poststretch isometric contractions resulted in supramaximal levels of poststretch isometric torque without increased activation of biceps femoris long head.

scholarly journals Biceps Femoris Activation during Hamstring Strength Exercises: A Systematic Review

2021 ◽  
Vol 18 (16) ◽  
pp. 8733
Author(s):  
Luis Llurda-Almuzara ◽  
Noé Labata-Lezaun ◽  
Carlos López-de-Celis ◽  
Ramón Aiguadé-Aiguadé ◽  
Sergi Romaní-Sánchez ◽  
...  
Keyword(s):  
Systematic Review ◽  
Isometric Contraction ◽  
Biceps Femoris ◽  
Cochrane Library ◽  
Exclusion Criteria ◽  
Maximal Voluntary Isometric Contraction ◽  
Cross Sectional ◽  
Strength Exercises ◽  
Long Head ◽  
Biceps Femoris Long Head

Background: The aim of the study was to systematically evaluate the biceps femoris long head activation across cross-sectional hamstring strength exercise studies. Methods: A systematic review design was followed. The search strategy conducted in PubMed, Cochrane Library, and Web of Sciences databases found a total of 3643 studies. Once inclusion and exclusion criteria were applied, 29 studies were finally included in this systematic review. A total of 507 participants and 114 different exercises were analyzed. Exercises were evaluated individually and grouped into several categories: Nordics, isokinetic exercises, lunges, squats, deadlifts, good mornings, hip thrusts, bridges, leg curls, swings, hip and back extensions, and others. Results: Results showed the isokinetic and Nordic exercises as the categories with highest biceps femoris activation (>60% of Maximal Voluntary Isometric Contraction). Nordic hamstring exercise ankle dorsiflexion was the exercise that achieved the highest biceps femoris long head activation (128.1% of its Maximal Voluntary Isometric Contraction). Conclusions: The results from this systematic review suggest that isokinetic and Nordic exercises seem to be the best option to activate biceps femoris long head. Future studies evaluating the implementation of these exercises in prevention programs are needed.

scholarly journals Effects of knee flexor submaximal isometric contraction until exhaustion on semitendinosus and biceps femoris long head shear modulus in healthy individuals

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bruno Mendes ◽  
Telmo Firmino ◽  
Raúl Oliveira ◽  
Tiago Neto ◽  
Carlos Cruz-Montecinos ◽  
...  
Keyword(s):  
Isometric Contraction ◽  
Shear Wave Elastography ◽  
Biceps Femoris ◽  
Time To Exhaustion ◽  
Healthy Individuals ◽  
Maximal Voluntary Isometric Contraction ◽  
Knee Flexor ◽  
Task Time ◽  
Long Head ◽  
Biceps Femoris Long Head

Abstract This study examined whether a knee flexor isometric contraction at 20% of maximal voluntary isometric contraction until exhaustion would alter the biceps femoris long head (BFlh) and semitendinosus (ST) active stiffness, assessed using ultrasound-based shear wave elastography. Twelve healthy individuals participated in 2 sessions separated by 7 days. Time to exhaustion was similar in both sessions (day 1: 443.8 ± 192.5 s; day 2: 474.6 ± 131.7 s; p = 0.323). At the start of the fatigue task, the ST showed greater active stiffness than the BFlh (p < 0.001), with no differences between days (p = 0.08). The ST active stiffness then decreased from 40% of the task time to exhaustion (− 2.2 to − 13.3%, p = 0.027) until the end of the task (− 16.1 to − 22.9%, p = 0.012), while no significant changes were noted in the BFlh (p = 0.771). Immediately after the fatigue task, a decrease in active stiffness was observed in the ST (− 11.8 to − 17.8%, p < 0.001), but not in the BFlh (p = 0.551). Results were consistent between the 2 testing sessions (p = 0.07–0.959). The present results indicate that fatigue alters the hamstring active stiffness pattern.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

Muscle- and Region-Specific Associations Between Muscle Size and Muscular Strength During Hip Extension and Knee Flexion in the Hamstrings

2021 ◽  
pp. 1-6
Author(s):  
Raki Kawama ◽  
Masamichi Okudaira ◽  
Hirohiko Maemura ◽  
Satoru Tanigawa
Keyword(s):  
Knee Flexion ◽  
Muscular Strength ◽  
Sports Injuries ◽  
Biceps Femoris ◽  
Muscle Size ◽  
Cross Sectional ◽  
Long Head ◽  
Hip Extension ◽  
Flexion Strength ◽  
Biceps Femoris Long Head

Context: Strength deficits of the hamstrings following sports injuries decrease athletic performance and increase the risk of injury recurrence. Previous studies have shown a high correlation between the muscular strength during hip-extension and knee-flexion and total muscle size of the hamstrings. However, it remains unclear which region of the individual hamstring muscles is closely associated with muscular strength. Objective: To investigate the relationship between the size of each region of the individual hamstring muscles and muscular strength during hip extension and knee flexion. Design: Within-subject repeated measures. Setting: University laboratory. Participants: Twenty healthy young male volunteers who regularly engaged in sports activities. Outcome Measures: Anatomical cross-sectional areas were acquired from the proximal, middle, and distal regions of the biceps femoris long head, biceps femoris short head, semitendinosus, and semimembranosus. Hip-extension and knee-flexion strength were measured during maximal voluntary isometric and concentric contractions (angular velocities of 60°/s and 180°/s). Results: The anatomical cross-sectional area of the distal regions in biceps femoris long head (r = .525–.642) and semitendinosus (r = .567) were significantly correlated with hip-extension strength under all conditions and only at an angular velocity of 180°/s, respectively. Meanwhile, anatomical cross-sectional areas of the distal regions in biceps femoris short head (r = .587–.684) and semimembranosus (r = .569–.576) were closely associated with knee-flexion strength under all conditions. Conclusion: These results suggest that muscle size in the distal regions of biceps femoris long head and semitendinosus greatly contributes to the production of hip-extension strength, whereas that of biceps femoris short head and semimembranosus significantly contributes to the generation of knee-flexion strength. These findings could be useful for designing training and rehabilitation programs to efficiently improve strength deficits following sports injuries such as strain injury and anterior cruciate ligament tears.

IS BICEPS FEMORIS LONG HEAD APONEUROSIS SIZE A RISK FACTOR FOR HAMSTRING STRAIN INJURY?

2014 ◽  
Vol 48 (7) ◽  
pp. 591.2-592 ◽  
Author(s):  
PE Evangelidis ◽  
GJ Massey ◽  
MT Pain ◽  
JP Folland
Keyword(s):  
Risk Factor ◽  
Biceps Femoris ◽  
Hamstring Strain ◽  
Long Head ◽  
Biceps Femoris Long Head

scholarly journals Biceps Femoris Long Head Muscle Fascicles Actively Lengthen During the Nordic Hamstring Exercise

2021 ◽  
Vol 3 ◽  
Author(s):  
Brent J. Raiteri ◽  
Ronja Beller ◽  
Daniel Hahn
Keyword(s):  
Knee Flexion ◽  
Injury Risk ◽  
Biceps Femoris ◽  
Muscle Architecture ◽  
Muscle Action ◽  
Hamstring Muscle ◽  
Tracking Algorithms ◽  
Muscle Fascicle ◽  
Long Head ◽  
Biceps Femoris Long Head

Current debate exists around whether a presumed eccentric exercise, the Nordic hamstring exercise (NHE), actually causes active hamstring muscle lengthening. This is because of the decoupling that can occur between the muscle fascicle and muscle-tendon unit (MTU) length changes in relatively compliant human lower-limb MTUs, which results in MTU lengthening not necessarily causing muscle fascicle lengthening. This missing knowledge complicates the interpretation of why the NHE is effective at reducing running-related hamstring muscle injury risk in athletes previously unfamiliar with performing this exercise. The purpose of the study was therefore to investigate if the most-commonly injured hamstring muscle, the biceps femoris long head (BF), exhibits active muscle lengthening (i.e. an eccentric muscle action) during the NHE up until peak force in Nordic novices. External reaction force at the ankle, knee flexion angle, and BF and semitendinosus muscle activities were recorded from the left leg of 14 participants during the NHE. Simultaneously, BF muscle architecture was imaged using B-mode ultrasound imaging, and muscle architecture changes were tracked using two different tracking algorithms. From ~85 to 100% of peak NHE force, both tracking algorithms detected that BF muscle fascicles (n = 10) significantly lengthened (p &lt; 0.01) and had a mean positive lengthening velocity (p ≤ 0.02), while knee extension velocity remained positive (17°·s−1) over knee flexion angles from 53 to 37° and a duration of 1.6 s. Despite some individual cases of brief isometric fascicle behavior and brief fascicle shortening during BF MTU lengthening, the predominant muscle action was eccentric under a relatively high muscle activity level (59% of maximum). Eccentric hamstring muscle action therefore does occur during the NHE in relatively strong (429 N) Nordic novices, which might contribute to the increase in resting BF muscle fascicle length and reduction in running-related injury risk, which have previously been reported following NHE training. Whether an eccentric BF muscle action occurs in individuals accustomed to the NHE remains to be tested.

Motion and Strain Along the Musculotendon Junction of the Biceps Femoris: Shortening vs. Lengthening Contractions

2009 ◽  
Author(s):  
Amy Silder ◽  
Darryl G. Thelen
Keyword(s):  
Mechanical Strain ◽  
Return To Sport ◽  
Biceps Femoris ◽  
Post Injury ◽  
Lengthening Contractions ◽  
Hamstring Strain ◽  
Long Head ◽  
Biceps Femoris Long Head ◽  
Shortening Contractions

Acute muscle strain injuries typically occur during active lengthening contractions, and tend to present along or near a musculotendon junction (MTJ) [1]. For example, among sprinters, the majority of hamstring strain injuries involve the proximal MTJ of the biceps femoris long head [1,2]. We have previously shown that post-injury scarring at the MTJ can persist for many months after return to sport [2], which may contribute to the high risk for re-injury associated with these injuries. Thus, it is pertinent to understand why the MTJ is susceptible to injury, and ultimately how post-injury remodeling may alter in-vivo mechanics. The purpose of the current study was to use dynamic magnetic resonance (MR) imaging to visualize muscle tissue displacements and mechanical strains during active lengthening contractions in the biceps femoris. We hypothesized that active lengthening contractions would induce greater mechanical strain along the proximal MTJ, when compared to shortening contractions of similar loads and ranges of motion.

Rate of Torque and Electromyographic Development During Anticipated Eccentric Contraction Is Lower in Previously Strained Hamstrings

2012 ◽  
Vol 41 (1) ◽  
pp. 116-125 ◽  
Author(s):  
David A. Opar ◽  
Morgan D. Williams ◽  
Ryan G. Timmins ◽  
Nuala M. Dear ◽  
Anthony J. Shield
Keyword(s):  
Eccentric Contraction ◽  
Biceps Femoris ◽  
Injured Limb ◽  
Myoelectrical Activity ◽  
Recreational Athletes ◽  
Hamstring Strain ◽  
History Of ◽  
Long Head ◽  
Biceps Femoris Long Head ◽  
Torque Development

Background: The effect of prior strain injury on myoelectrical activity of the hamstrings during tasks requiring high rates of torque development has received little attention. Purpose: To determine if recreational athletes with a history of unilateral hamstring strain injury will exhibit lower levels of myoelectrical activity during eccentric contraction, rate of torque development (RTD), and impulse (IMP) at 30, 50, and 100 milliseconds after the onset of myoelectrical activity or torque development in the previously injured limb compared with the uninjured limb. Study Design: Case control study; Level of evidence, 3. Methods: Twenty-six recreational athletes were recruited. Of these, 13 athletes had a history of unilateral hamstring strain injury (all confined to biceps femoris long head), and 13 had no history of hamstring strain injury. Following familiarization, all athletes undertook isokinetic dynamometry testing and surface electromyography (integrated EMG; iEMG) assessment of the biceps femoris long head and medial hamstrings during eccentric contractions at −60 and −180 deg·s−1. Results: In the injured limb of the injured group, compared with the contralateral uninjured limb, RTD and IMP was lower during −60 deg·s−1 eccentric contractions at 50 milliseconds (RTD: injured limb, 312.27 ± 191.78 N·m·s−1 vs uninjured limb, 518.54 ± 172.81 N·m·s−1, P = .008; IMP: injured limb, 0.73 ± 0.30 N·m·s vs uninjured limb, 0.97 ± 0.23 N·m·s, P = .005) and 100 milliseconds (RTD: injured limb, 280.03 ± 131.42 N·m·s−1 vs uninjured limb, 460.54 ± 152.94 N·m·s−1, P = .001; IMP: injured limb, 2.15 ± 0.89 N·m·s vs uninjured limb, 3.07 ± 0.63 N·m·s, P < .001) after the onset of contraction. Biceps femoris long head muscle activation was lower at 100 milliseconds at both contraction speeds (–60 deg·s−1, normalized iEMG activity [×1000]: injured limb, 26.25 ± 10.11 vs uninjured limb, 33.57 ± 8.29, P = .009; –180 deg·s−1, normalized iEMG activity [×1000]: injured limb, 31.16 ± 10.01 vs uninjured limb, 39.64 ± 8.36, P = .009). Medial hamstring activation did not differ between limbs in the injured group. Comparisons in the uninjured group showed no significant between limbs difference for any variables. Conclusion: Previously injured hamstrings displayed lower RTD and IMP during slow maximal eccentric contraction compared with the contralateral uninjured limb. Lower myoelectrical activity was confined to the biceps femoris long head. Regardless of whether these deficits are the cause of or the result of injury, these findings could have important implications for hamstring strain injury and reinjury. Particularly, given the importance of high levels of muscle activity to bring about specific muscular adaptations, lower levels of myoelectrical activity may limit the adaptive response to rehabilitation interventions and suggest that greater attention be given to neural function of the knee flexors after hamstring strain injury.

scholarly journals Effect of Nordic Hamstring Exercise Training on Knee Flexors Eccentric Strength and Fascicle Length: A Systematic Review and Meta-Analysis

2020 ◽  
pp. 1-10
Author(s):  
Diulian Muniz Medeiros ◽  
César Marchiori ◽  
Bruno Manfredini Baroni
Keyword(s):  
Systematic Review ◽  
Confidence Interval ◽  
Randomized Clinical Trials ◽  
Evidence Synthesis ◽  
Meta Analysis ◽  
Biceps Femoris ◽  
Fascicle Length ◽  
Long Head ◽  
Biceps Femoris Long Head ◽  
Knee Flexors

Context: Nordic hamstring exercise (NHE) has been widely employed to prevent hamstring strain injuries. However, it is still not clear which adaptations are responsible for the NHE preventive effects. Objectives: The aim of this study was to investigate the effects of NHE on knee flexors eccentric strength and fascicle length. Evidence Acquisition: The search strategy included MEDLINE, PEDro, and Cochrane CENTRAL from inception to April 2020. Randomized clinical trials that have analyzed the effects of NHE training on hamstring eccentric strength and/or fascicle length were included. Evidence Synthesis: From the 1932 studies identified, 12 were included in the systematic review, and 9 studies presented suitable data for the meta-analysis. All studies demonstrated strength increments in response to NHE training (10%–15% and 16%–26% in tests performed on the isokinetic dynamometer and on the NHE device, respectively), as well as significant enhancement of biceps femoris long head fascicle length (12%–22%). Meta-analysis showed NHE training was effective to increase knee flexors eccentric strength assessed with both isokinetic tests (0.68; 95% confidence interval, 0.29 to 1.06) and NHE tests (1.11; 95% confidence interval, 0.62 to 1.61). NHE training was also effective to increase fascicle length (0.97; 95% confidence interval, 0.46 to 1.48). Conclusions: NHE training has the potential of increasing both knee flexors eccentric strength and biceps femoris long head fascicle length.

scholarly journals Regional Differences in Biceps Femoris Long Head Stiffness during Isometric Knee Flexion

2021 ◽  
Vol 6 (1) ◽  
pp. 18
Author(s):  
João R. Vaz ◽  
Tiago Neto ◽  
José Pedro Correia ◽  
Jorge Infante ◽  
Sandro R. Freitas
Keyword(s):  
Knee Flexion ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Proximal Region ◽  
Muscle Stiffness ◽  
Future Research ◽  
Maximum Voluntary Isometric Contraction ◽  
Study Results ◽  
Long Head ◽  
Biceps Femoris Long Head

This study sought to investigate whether the stiffness of the biceps femoris long head differs between proximal and distal regions during isometric knee flexion at different contraction intensities and muscle lengths. Twelve healthy individuals performed knee flexion isometric contractions at 20% and 60% of maximum voluntary isometric contraction, with the knee flexed at 15 and 45 degrees. Muscle stiffness assessment was performed using ultrasound-based shear wave elastography. Proximal and distal regions of the biceps femoris long head were assessed. Biceps femoris long head muscle showed a greater stiffness (i) in the distal region, (ii) at higher contraction intensity, and (iii) at longer muscle length. The proximal-to-distal stiffness ratio was significantly lower than 1 (i.e., heterogenous) at lower contraction intensity regardless of the muscle length. However, this was not observed at higher contraction intensity. This study is the first to show heterogeneity in the active stiffness of the biceps femoris long head. Given the greater incidence of injury at the proximal region of biceps femoris long head, this study opens new directions for future research. Additionally, the present study results indicate that studies assessing muscle stiffness at one single muscle region should be interpreted with caution.

Sign in / Sign up

Export Citation Format

Share Document