Biceps femoris long head sarcomere and fascicle length adaptations after 3 weeks of eccentric exercise training

Pincheira, Patricio A.; Boswell, Melissa A; Franchi, Martino V.; Delp, Scott L.; Lichtwark, Glen A.

doi:10.1016/j.jshs.2021.09.002

Cited by 50 publications

(45 citation statements)

References 41 publications

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“…The addition of sarcomeres in series has been suggested to be an adaptive muscle mechanism in response to exercise-induced muscle damage (Proske and Morgan 2001 ). However, recent evidence suggests that increases in sarcomere length, rather than sarcomere number, may explain the increase in L f observed following 3 weeks’ eccentric resistance training (Pincheira et al 2021 ). Thus, as sarcomeres were not measured in the present study, further work is required to investigate the mechanisms underpinning the increases in VL L f elicited by short-term DR training.…”

Section: Discussionmentioning

confidence: 99%

“…Data are presented as mean ± SD MVT maximal voluntary torque, ACSA anatomical cross-sectional area, ML muscle length, PCSA physiological cross-sectional area in response to exercise-induced muscle damage(Proske and Morgan 2001). However, recent evidence suggests that increases in sarcomere length, rather than sarcomere number, may explain the increase in L f observed following 3 weeks' eccentric resistance training(Pincheira et al 2021). Thus, as sarcomeres were not measured in the present study, further work is required to investigate the mechanisms underpinning the increases in VL L f elicited by short-term DR training.Strength improvements observed after a period of resistance training are also partly underpinned by adaptations of the central nervous system (for recent reviewsHortobágyi et al 2021;Aagaard et al 2020;Siddique et al 2020;Pearcey et al 2021; Skarabot et al 2021).…”

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confidence: 99%

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The time course of different neuromuscular adaptations to short-term downhill running training and their specific relationships with strength gains

et al. 2022

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Purpose Due to its eccentric nature, downhill running (DR) training has been suggested to promote strength gains through neuromuscular adaptations. However, it is unknown whether short-term chronic DR can elicit such adaptations. Methods Twelve untrained, young, healthy adults (5 women, 7 men) took part in 4 weeks’ DR, comprising 10 sessions, with running speed equivalent to 60–65% maximal oxygen uptake ($$\dot{V}$$ V ˙ O2max, assessed at weeks 0 and 4). Isometric and isokinetic knee-extensor maximal voluntary torque (MVT), vastus lateralis (VL) muscle morphology/architecture (anatomical cross-sectional area, ACSA; physiological CSA, PCSA; volume; fascicle length, Lf; pennation angle, PA) and neuromuscular activation (VL EMG) were assessed at weeks 0, 2 and 4. Results MVT increased by 9.7–15.2% after 4 weeks (p < 0.01). VL EMG during isometric MVT increased by 35.6 ± 46.1% after 4 weeks (p < 0.05) and correlated with changes in isometric MVT after 2 weeks (r = 0.86, p = 0.001). VL ACSA (+2.9 ± 2.7% and +7.1 ± 3.5%) and volume (+2.5 ± 2.5% and +6.6 ± 3.2%) increased after 2 and 4 weeks, respectively (p < 0.05). PCSA (+3.8 ± 3.3%), PA (+5.8 ± 3.8%) and Lf (+2.7 ± 2.2%) increased after 4 weeks (p < 0.01). Changes in VL volume (r = 0.67, p = 0.03) and PCSA (r = 0.71, p = 0.01) correlated with changes in concentric MVT from 2 to 4 weeks. $$\dot{V}$$ V ˙ O2max (49.4 ± 6.2 vs. 49.7 ± 6.3 mL·kg−1·min−1) did not change after 4 weeks (p = 0.73). Conclusion Just 4 weeks’ moderate-intensity DR promoted neuromuscular adaptations in young, healthy adults, typically observed after high-intensity eccentric resistance training. Neural adaptations appeared to contribute to most of the strength gains at 2 and 4 weeks, while muscle hypertrophy seemed to contribute to MVT changes from 2 to 4 weeks only.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

The time course of different neuromuscular adaptations to short-term downhill running training and their specific relationships with strength gains

et al. 2022

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“…For example, intraoperative measures of sarcomeres have been shown to be much longer in children with cerebral palsy (an injury of the brain during development) than sarcomere length estimates for Mathewson et al (2015) (∼88%) or intraoperative measures ( Lieber and Fridén, 2019 ) (∼46%) in typically developing children. In addition, following 3 weeks of Nordic hamstring training, a 17% increase in sarcomere length was found in the biceps femoris long head ( Pincheira et al, 2021 ). Due to the relative ease of obtaining fascicle length measures as compared to sarcomere length measures in vivo , many studies have reported adaptation of fascicle length to altered use or stimulus.…”

Section: Discussionmentioning

confidence: 99%

Variability of in vivo Sarcomere Length Measures in the Upper Limb Obtained With Second Harmonic Generation Microendoscopy

et al. 2022

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The lengths of a muscle’s sarcomeres are a primary determinant of its ability to contract and produce force. In addition, sarcomere length is a critical parameter that is required to make meaningful comparisons of both the force-generating and excursion capacities of different muscles. Until recently, in vivo sarcomere length data have been limited to invasive or intraoperative measurement techniques. With the advent of second harmonic generation microendoscopy, minimally invasive measures of sarcomere length can be made for the first time. This imaging technique expands our ability to study muscle adaptation due to changes in stimulus, use, or disease. However, due to past inability to measure sarcomeres outside of surgery or biopsy, little is known about the natural, anatomical variability in sarcomere length in living human subjects. To develop robust experimental protocols that ensure data provide accurate representations of a muscle’s sarcomere lengths, we sought to quantify experimental uncertainty associated with in vivo measures of sarcomere lengths. Specifically, we assessed the variability in sarcomere length measured (1) within a single image, along a muscle fiber, (2) across images captured within a single trial, across trials, and across days, as well as (3) across locations in the muscle using second harmonic generation in two upper limb muscles with different muscle architectures, functions, and sizes. Across all of our measures of variability we estimate that the magnitude of the uncertainty for in vivo sarcomere length is on the order of ∼0.25 μm. In the two upper limb muscles studied we found larger variability in sarcomere lengths within a single insertion than across locations. We also developed custom code to make measures of sarcomere length variability across a single fiber and determined that this codes’ accuracy is an order of magnitude smaller than our measurement uncertainty due to sarcomere variability. Together, our findings provide guidance for the development of robust experimental design and analysis of in vivo sarcomere lengths in the upper limb.

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“…By comparison, Franchi, Reeves, and Narici [46] highlighted that the underlying myogenic and molecular responses may be different in eccentric and concentric muscle actions because the eccentric training is considered to favour increases in fascicle length, and concentric training to favour higher increments of pennation angle [46]. A recent study by Pincheira et al [49] showed that eccentric training can increase fascicle length by increasing sarcomere lengths. Another study stated that concentric, eccentric and isometric exercises can lead to similar increases in total DNA and RNA quantities, which are representative of muscle hypertrophy; however, concentric and isometric training increases muscle insulin-like growth factor 1 mRNA levels, whereas eccentric training does not increase these levels [46].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Resistance Training on Architecture and Volume of the Upper Extremity Muscles: A Systematic Review of Randomised Controlled Trials and Meta-Analyses

et al. 2022

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To systematically review the effects of exercise on fascicle geometry and muscle size parameters of the upper extremity muscles, the CENTRAL, CINAHL, PubMed and OpenGrey databases were searched on 31 July 2021. Finally, 17 randomised controlled trials (RCTs) were included in this systematic review. High-intensity bench press training (g = 1.03) and 12 RM bench press exercises (g = 1.21) showed a large effect size on increasing pectoralis major muscle size. In the elbow extensors, large effects were reported for an increase in muscle size with isometric maximal voluntary co-contraction training (g = 1.97), lying triceps extension exercise (g = 1.25), and nonlinear periodised resistance training (g = 2.07). In addition, further large effects were achieved in the elbow flexors via traditional elbow flexion exercises (g = 0.93), concentric low-load forearm flexion-extension training (g = 0.94, g = 1), isometric maximal voluntary co-contraction training (g = 1.01), concentric low-load forearm flexion-extension training with blood flow restriction (g = 1.02, g = 1.07), and nonlinear periodised resistance training (g = 1.13, g = 1.34). Regarding the forearm muscles, isometric ulnar deviation training showed a large effect (g = 2.22) on increasing the flexor carpi ulnaris and radialis muscle size. Results show that these training modalities are suitable for gaining hypertrophy in the relevant muscles with at least four weeks of training duration. Future RCTs should investigate the effects of exercise modalities on the triceps brachii fascicle geometry, the infraspinatus muscle thickness (MT) and the subscapular MT due to their associations with sports performance.

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Biceps femoris long head sarcomere and fascicle length adaptations after 3 weeks of eccentric exercise training

Cited by 50 publications

References 41 publications

The time course of different neuromuscular adaptations to short-term downhill running training and their specific relationships with strength gains

The time course of different neuromuscular adaptations to short-term downhill running training and their specific relationships with strength gains

Variability of in vivo Sarcomere Length Measures in the Upper Limb Obtained With Second Harmonic Generation Microendoscopy

The Effects of Resistance Training on Architecture and Volume of the Upper Extremity Muscles: A Systematic Review of Randomised Controlled Trials and Meta-Analyses

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