The influence of training-induced sarcomerogenesis on the history dependence of force

Chen, Jackey; Mashouri, Parastoo; Fontyn, Stephanie; Valvano, Mikella; Elliott-Mohamed, Shakeap; Noonan, Alex M.; Brown, Stephen H.M.; Power, Geoffrey A.

doi:10.1101/2020.03.31.018895

Cited by 7 publications

(19 citation statements)

References 76 publications

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“…Similarly to Blazevich et al (2003) , our results show increases in VL Lf following PLT; this phenomenon is expected to reflect an increase in the number of sarcomeres in series, and thus in maximum shortening velocity ( Bodine et al, 1982 ). Animal studies have shown that sarcomere addition can occur already after 5, 10, and 28 days in response to training modalities involving muscle lengthening ( Lynn et al, 1998 ; Butterfield et al, 2005 ; Chen et al, 2020 ). However, recent studies in intact whole mice muscle have described some variability in sarcomere length along different muscle regions ( Moo et al, 2016 ), which become even more non-uniform upon activation ( Moo et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

The Time-Course of Changes in Muscle Mass, Architecture and Power During 6 Weeks of Plyometric Training

et al. 2020

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To investigate the time-course of changes in knee-extensors muscle mass, architecture and function in response to plyometric training (PLT) performed on a novel training device, the Tramp-Trainer. This machine consists in a trampoline connected to an inclined sledge which allows the performance of repeated jumps while the subject is sitting on a chair. Methods: Eight healthy males (173.6 ± 4.7 cm, 69.7 ± 13.5 kg, 25.3 ± 4.6 years) underwent 6 weeks of bilateral PLT on the tramp-trainer machine. Training was performed three times per week (between 120 and 150 bounces per session). Kneeextensor maximum voluntary torque (MVT) and power, quadriceps femoris (QF) volume (VOL), cross-sectional area from the 20% to the 60% of femur length and CSA mean , together with vastus lateralis (VL) architecture (fascicle length, Lf, and pennation angle, PA) were assessed after 2, 4, and 6 weeks of PLT. Results: All results are presented as changes versus baseline values. MVT increased by 17.8% (week 2, p < 0.001) and 22.2% (week 4, p < 0.01), respectively, and declined to 13.3% (p < 0.05) at week 6 of PLT. Power increased by 18.2% (week 4, p < 0.05) and 19.7% (week 6, p < 0.05). QF VOL increased by 4.7% (week 4, p < 0.05) and 5.8% (week 6, p < 0.01); VL VOL increased by 5.2%, (p < 0.05), 8.2%, (p < 0.01), and 9.6% (p < 0.05) at weeks 2, 4, and 6, respectively. An increase in Lf was detected already at wk 2 (2.2%, p < 0.05), with further increase at 4 and 6 weeks of PLT (4 and 4.4%, respectively, p < 0.01). PA increased by 5.8% (p < 0.05) at week 6. Significant positive correlations were found between CSA mean and Power (R 2 = 0.46, p < 0.001) and between QF VOL and Power (R 2 = 0.44, p < 0.024). Conclusions: PLT induced rapid increases in muscle volume, fascicle length, pennation angle, torque and power in healthy younger adults. Notably, changes in VL VOL and Lf were detectable already after 2 weeks, followed by increases in knee extensors

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Section: Discussionmentioning

confidence: 99%

The Time-Course of Changes in Muscle Mass, Architecture and Power During 6 Weeks of Plyometric Training

et al. 2020

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“…It is generally accepted that the anti-gravity plantarflexors (including SOL) and knee extensors (including VI) are loaded primarily eccentrically during DH running and concentrically during UH running (Margaria, 1968;Armstrong et al, 1983;Butterfield et al, 2005;Maeo et al, 2017). Separate work on the animals tested in the current study (Chen et al, 2020) demonstrated that the EDL had a greater number of sarcomeres in series in both DH and UH training groups compared to the sedentary control group, which may suggest that the EDL performed meaningful eccentric contractions during both DH and UH running.…”

Section: Discussionmentioning

confidence: 51%

“…At the start of each training session, rats started at a walking speed of 10 m/min, which was gradually increased to 16 m/min, at a rate of 1 m/min. Each training session was delivered in a series of 5 min bouts (i.e., 3 on day 1 and 7 on days 5 to the end of the 4 week period) with 2 min or rest between each bout (Chen et al, 2020).…”

Section: Training Protocolmentioning

confidence: 99%

Training Induced Changes to Skeletal Muscle Passive Properties Are Evident in Both Single Fibers and Fiber Bundles in the Rat Hindlimb

et al. 2020

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Introduction: The passive mechanical behavior of skeletal muscle represents both important and generally underappreciated biomechanical properties with little attention paid to their trainability. These experiments were designed to gain insight into the trainability of muscle passive mechanical properties in both single fibers and fiber bundles. Methods: Rats were trained in two groups: 4 weeks of either uphill (UH) or downhill (DH) treadmill running; with a third group as sedentary control. After sacrifice, the soleus (SOL), extensor digitorum longus (EDL), and vastus intermedius (VI) were harvested. One hundred seventy-nine bundles and 185 fibers were tested and analyzed using a cumulative stretchrelaxation protocol to determine the passive stress and elastic modulus. Titin isoform expression was analyzed using sodium dodecyl sulfate vertical agarose gel electrophoresis (SDS-VAGE). Results: Single fibers: passive modulus and stress were greater for the EDL at sarcomere lengths (SLs) ≥ 3.7 μm (modulus) and 4.0 μm (stress) with DH training compared to UH training and lesser for the SOL (SLs ≥ 3.3 μm) with DH training compared with control; there was no effect of UH training. Vastus intermedius was not affected by either training protocol. Fiber bundles: passive modulus and stress were greater for the EDL at SLs ≥ 2.5 μm (modulus) and 3.3 μm (stress) in the DH training group as compared with control, while no affects were observed in either the SOL or VI for either training group. No effects on titin isoform size were detected with training. Conclusion: This study demonstrated that a trainability of passive muscle properties at both the single fiber and fiber bundle levels was not accompanied by any detectable changes to titin isoform size.

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“…Furthermore, running on many consecutive days may minimize time for recovery and hence remodelling between exercise bouts (Hyldahl and Hubal, 2014). This distinction in training stimuli was offered previously as explanation for observations of only small adaptations in rat soleus SSN and mechanical function following downhill running training (Chen et al, 2020). Larger magnitude changes in muscle architecture and strength in animals following 3 days/week training programs support this perspective as well (Butterfield and Herzog, 2006;Ochi et al, 2007;Zhu et al, 2021).…”

Section: Introductionmentioning

confidence: 74%

“…They completed 3 bouts on the first day and increased by 2 bouts/day up to the 7-bout target (35 minutes total) on the third day of training, which persisted for the remainder of the training period. Rats began each training session at a speed of 10 m/min, which was increased by 1 m/min up to the 16 m/min target (Chen et al, 2020). Progressive loading was employed by adding weight equivalent to 5% of the rat's body mass during the first week, 10% in the second week, 15% in the third week, and 15% readjusted to the new body mass in the fourth week.…”

Section: Methodsmentioning

confidence: 99%

An increase in serial sarcomere number induced via weighted downhill running improves work loop performance in the rat soleus

Hinks

Jacob

Mashouri

et al. 2022

Preprint

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Increased serial sarcomere number (SSN) has been observed in rats via downhill running training due to the emphasis on active lengthening contractions; however, little is known about the influence on dynamic contractile function. Therefore, we employed 4 weeks of weighted downhill running training in rats, then assessed soleus SSN and work loop performance. We hypothesized trained rats would produce greater net work output during faster, higher-strain work loops due to a greater SSN. Thirty-one Sprague-Dawley rats were assigned to control or training groups. Weight was added during running via a custom-made vest, progressing from 5-15% body mass. Following sacrifice, the soleus was dissected, and a force-length relationship was constructed. Work loops (active shortening followed by passive lengthening) were then performed about optimal muscle length (LO) at 1.5-3-Hz cycle frequencies and 1-7-mm strains, to assess net work output. Next, muscles were fixed in formalin at LO. Fascicle lengths and sarcomere lengths were measured and used to calculate SSN. Intramuscular collagen content and crosslinking were quantified via a hydroxyproline content and pepsin-solubility assay. Trained rats had longer fascicle lengths (+13%), greater SSN (+8%), greater specific active forces (+50%), and lower passive forces (45-62%) than controls (P<0.05). There were no differences in collagen parameters (P>0.05). Net work output was greater (+101-424%) in trained than control rats for the 1.5-Hz loops at 1, 3, and 5-mm strains (P<0.05) and showed relationships with fascicle length (R2=0.14-0.24, P<0.05). These results suggest training-induced longitudinal muscle growth may improve dynamic performance.

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The influence of training-induced sarcomerogenesis on the history dependence of force

Cited by 7 publications

References 76 publications

The Time-Course of Changes in Muscle Mass, Architecture and Power During 6 Weeks of Plyometric Training

The Time-Course of Changes in Muscle Mass, Architecture and Power During 6 Weeks of Plyometric Training

Training Induced Changes to Skeletal Muscle Passive Properties Are Evident in Both Single Fibers and Fiber Bundles in the Rat Hindlimb

An increase in serial sarcomere number induced via weighted downhill running improves work loop performance in the rat soleus

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