Biceps femoris long head muscle fascicle length does not differ between sexes

AbstractPurposeEccentric exercise is widely used to increase muscle fascicle lengths and thus decrease the risk of muscle strain injuries. However, the mechanisms behind this protection are still unknown. The aim of this study was to determine whether Biceps femoris long head (BFlh) fascicle length increases in response to three weeks of eccentric exercise training are the result of addition of in-series sarcomeres within muscle fibres.MethodsTen recreationally active participants (age: 27 ± 3 years, mass: 70 ± 14 kg, height: 174 ± 9 cm) completed three weeks of Nordic hamstring exercise (NHE) training. We collected in vivo sarcomere and muscle fascicle images of the BFlh in two regions (central and distal), utilising microendoscopy and 3D ultrasonography. These images allowed us to estimate sarcomere length, sarcomere number and fascicle lengths before and after the training intervention.ResultsEccentric knee flexion strength increased after the training (15%, P < 0.001, ηp2= 0.75). Further, we found a significant increase in fascicle (21%, P < 0.001, ηp2 = 0.81) and sarcomere (17%, P < 0.001, ηp2 = 0.9) lengths in the distal but not in the central portion of the muscle. The estimated number of in series sarcomeres did not change in either region.ConclusionFascicle length adaptations appear to be heterogeneous in the BFlf in response to three weeks of NHE training. An increase in sarcomere length, rather than the addition of sarcomeres in series, appears to be underlying this adaptation. The mechanism driving regional increases in fascicle and sarcomere length remain unknown, but we speculate it may be driven by regional changes in the passive tension of muscle or connective tissue adaptations.

Download Full-text

Poor agreement between ultrasound and inbuilt diffusion tensor MRI measures of biceps femoris long head fascicle length

Translational Sports Medicine ◽

10.1002/tsm2.58 ◽

2018 ◽

Vol 2 (2) ◽

pp. 58-63 ◽

Cited By ~ 3

Author(s):

Fearghal P. Behan ◽

Robin Vermeulen ◽

Tessa Smith ◽

Javier Arnaiz ◽

Rodney Whiteley ◽

...

Keyword(s):

Diffusion Tensor ◽

Biceps Femoris ◽

Diffusion Tensor Mri ◽

Poor Agreement ◽

Fascicle Length ◽

Long Head ◽

Biceps Femoris Long Head

Download Full-text

Hamstring Eccentric Strengthening Program: Does Training Volume Matter?

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0947 ◽

2020 ◽

Vol 15 (1) ◽

pp. 81-90 ◽

Cited By ~ 6

Author(s):

Mathieu Lacome ◽

Simon Avrillon ◽

Yannick Cholley ◽

Ben M. Simpson ◽

Gael Guilhem ◽

...

Keyword(s):

Biceps Femoris ◽

High Volume ◽

Soccer Players ◽

Eccentric Training ◽

Fascicle Length ◽

Knee Flexor ◽

Low Volume ◽

Long Head ◽

Biceps Femoris Long Head ◽

Flexor Strength

Aim: To compare the effect of low versus high volume of eccentric-biased hamstring training programs on knee-flexor strength and fascicle length changes in elite soccer players. Methods: A total of 19 elite youth soccer players took part in this study and were randomly assigned into 2 subgroups. For 6 weeks in-season, the groups performed either a low-volume (1 set per exercise; 10 repetitions in total) or a high-volume (4 sets; 40 repetitions) eccentric training of their knee flexors. After 6-weeks midtraining (MID), players performed the alternate training regimen. Each training set consisted of 4 repetitions of the Nordic hamstring exercise and 6 repetitions of the bilateral stiff-leg deadlift. Eccentric knee-flexor strength (NordBord) as well as biceps femoris long head and semimembranosus fascicle length (scanned with ultrasound scanner) were assessed during pretraining (PRE), MID, and posttraining (POST) tests. Results: Knee-flexor eccentric strength very likely increased from PRE to MID (low volume: +11.3% [7.8%] and high volume: 11.4% [5.3%]), with a possibly-to-likely increase in biceps femoris long head (+4.5% [5.0%] and 4.8% [2.5%]) and semimembranosus (+4.3% [4.7%] and 6.3% [6.3%]) fascicle length in both groups. There was no substantial changes between MID and POST. Overall, there was no clear between-group difference in the changes from PRE to MID and MID to POST for neither knee-flexor eccentric strength, biceps femoris long head, nor semimembranosus fascicle length. Conclusions: Low-volume knee-flexor eccentric training is as effective as a greater training dose to substantially improve knee-flexor strength and fascicle length in-season in young elite soccer players. Low volume is, however, likely more appropriate to be used in an elite team facing congested schedules.

Download Full-text

Biceps femoris long head sarcomere and fascicle length adaptations after three weeks of eccentric exercise training

Journal of Sport and Health Science ◽

10.1016/j.jshs.2021.09.002 ◽

2021 ◽

Author(s):

Patricio A. Pincheira ◽

Melissa A. Boswell ◽

Martino V. Franchi ◽

Scott L. Delp ◽

Glen A. Lichtwark

Keyword(s):

Exercise Training ◽

Eccentric Exercise ◽

Biceps Femoris ◽

Fascicle Length ◽

Long Head ◽

Biceps Femoris Long Head

Download Full-text

Ultrasound-derived Biceps Femoris Long Head Fascicle Length

Medicine & Science in Sports & Exercise ◽

10.1249/mss.0000000000002123 ◽

2020 ◽

Vol 52 (1) ◽

pp. 233-243 ◽

Cited By ~ 7

Author(s):

MARTINO V. FRANCHI ◽

DANIEL P. FITZE ◽

BRENT J. RAITERI ◽

DANIEL HAHN ◽

JÖRG SPÖRRI

Keyword(s):

Biceps Femoris ◽

Fascicle Length ◽

Long Head ◽

Biceps Femoris Long Head

Download Full-text

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

Frontiers in Sports and Active Living ◽

10.3389/fspor.2021.669813 ◽

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 < 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.

Download Full-text