Eccentric ergometry: increases in locomotor muscle size and strength at low training intensities

2000 ◽  
Vol 278 (5) ◽  
pp. R1282-R1288 ◽  
Author(s):  
P. C. LaStayo ◽  
D. J. Pierotti ◽  
J. Pifer ◽  
H. Hoppeler ◽  
S. L. Lindstedt
Keyword(s):  
Energy Demand ◽  
Size Composition ◽  
Muscle Size ◽  
Trained Group ◽  
Cross Sectional ◽  
Functional Changes ◽  
Cycle Ergometers ◽  
Muscle Adaptations ◽  
Fiber Size ◽  
Skeletal Muscle Adaptations

Lengthening (eccentric) muscle contractions are characterized by several unusual properties that may result in unique skeletal muscle adaptations. In particular, high forces are produced with very little energy demand. Eccentrically trained muscles gain strength, but the specific nature of fiber size and composition is poorly known. This study assesses the structural and functional changes that occur to normal locomotor muscle after chronic eccentric ergometry at training intensities, measured as oxygen uptake, that do not influence the muscle when exercised concentrically. Male subjects trained on either eccentric or concentric cycle ergometers for 8 wk at a training intensity starting at 54% and ending at 65% of their peak heart rates. The isometric leg strength increased significantly in the eccentrically trained group by 36%, as did the cross-sectional area of the muscle fiber by 52%, but the muscle ultrastructure remained unchanged. There were no changes in either fiber size, composition, or isometric strength in the concentrically trained group. The responses of muscle to eccentric training appear to be similar to resistance training.

Strength and skeletal muscle adaptations in heavy-resistance-trained women after detraining and retraining

1991 ◽  
Vol 70 (2) ◽  
pp. 631-640 ◽  
Author(s):  
R. S. Staron ◽  
M. J. Leonardi ◽  
D. L. Karapondo ◽  
E. S. Malicky ◽  
J. E. Falkel ◽  
...  
Keyword(s):  
Strength Training ◽  
Lower Limb ◽  
Dynamic Strength ◽  
Fiber Types ◽  
Cross Sectional ◽  
Training Study ◽  
Muscle Adaptations ◽  
Fast Fiber ◽  
Skeletal Muscle Adaptations ◽  
Maximal Dynamic Strength

Six women who had participated in a previous 20-wk strength training study for the lower limb detrained for 30-32 wk and subsequently retrained for 6 wk. Seven untrained women also participated in the 6-wk "retraining" phase. In addition, four women from each group volunteered to continue training an additional 7 wk. The initial 20-wk training program caused an increase in maximal dynamic strength, hypertrophy of all three major fiber types, and a decrease in the percentage of type IIb fibers. Detraining had relatively little effect on fiber cross-sectional area but resulted in an increased percentage of type IIb fibers with a concomitant decrease in IIa fibers. Maximal dynamic strength decreased but not to pretraining levels. Retraining for 6 wk resulted in significant increases in the cross-sectional areas of both fast fiber types (IIa and IIab + IIb) compared with detraining values and a decrease in the percentage of type IIb fibers. The 7-wk extension accentuated these trends such that cross-sectional areas continued to increase (nonsignificant) and no IIb fibers could be found. Similar results were found for the nonpreviously trained women. These data suggest that rapid muscular adaptations occur as a result of strength training in previously trained as well as non-previously trained women. Some adaptations (fiber area and maximal dynamic strength) may be retained for long periods during detraining and may contribute to a rapid return to "competitive" form.

scholarly journals Skeletal Muscle Adaptations and Performance Outcomes Following a Step and Exponential Taper in Strength Athletes

2021 ◽  
Vol 12 ◽  
Author(s):  
S. Kyle Travis ◽  
Kevin A. Zwetsloot ◽  
Iñigo Mujika ◽  
Michael H. Stone ◽  
Caleb D. Bazyler
Keyword(s):  
Skeletal Muscle ◽  
Vastus Lateralis ◽  
Performance Outcomes ◽  
Maximal Strength ◽  
Cross Sectional ◽  
Time Effects ◽  
Muscle Adaptations ◽  
Skeletal Muscle Adaptations ◽  
Whole Muscle ◽  
Mhc Iia

Before major athletic events, a taper is often prescribed to facilitate recovery and enhance performance. However, it is unknown which taper model is most effective for peaking maximal strength and positively augmenting skeletal muscle. Thus, the purpose of this study was to compare performance outcomes and skeletal muscle adaptations following a step vs. an exponential taper in strength athletes. Sixteen powerlifters (24.0 ± 4.0 years, 174.4 ± 8.2 cm, 89.8 ± 21.4 kg) participated in a 6-week training program aimed at peaking maximal strength on back squat [initial 1-repetition-maximum (1RM): 174.7 ± 33.4 kg], bench press (118.5 ± 29.9 kg), and deadlift (189.9 ± 41.2 kg). Powerlifters were matched based on relative maximal strength, and randomly assigned to either (a) 1-week overreach and 1-week step taper or (b) 1-week overreach and 3-week exponential taper. Athletes were tested pre- and post-training on measures of body composition, jumping performance, isometric squat, and 1RM. Whole muscle size was assessed at the proximal, middle, and distal vastus lateralis using ultrasonography and microbiopsies at the middle vastus lateralis site. Muscle samples (n = 15) were analyzed for fiber size, fiber type [myosin-heavy chain (MHC)-I, -IIA, -IIX, hybrid-I/IIA] using whole muscle immunohistochemistry and single fiber dot blots, gene expression, and microRNA abundance. There were significant main time effects for 1RM squat (p < 0.001), bench press (p < 0.001), and deadlift, (p = 0.024), powerlifting total (p < 0.001), Wilks Score (p < 0.001), squat jump peak-power scaled to body mass (p = 0.001), body mass (p = 0.005), fat mass (p = 0.002), and fat mass index (p = 0.002). There were significant main time effects for medial whole muscle cross-sectional area (mCSA) (p = 0.006) and averaged sites (p < 0.001). There was also a significant interaction for MHC-IIA fiber cross-sectional area (fCSA) (p = 0.014) with post hoc comparisons revealing increases following the step-taper only (p = 0.002). There were significant main time effects for single-fiber MHC-I% (p = 0.015) and MHC-IIA% (p = 0.033), as well as for MyoD (p = 0.002), MyoG (p = 0.037), and miR-499a (p = 0.033). Overall, increases in whole mCSA, fCSA, MHC-IIA fCSA, and MHC transitions appeared to favor the step taper group. An overreach followed by a step taper appears to produce a myocellular environment that enhances skeletal muscle adaptations, whereas an exponential taper may favor neuromuscular performance.

scholarly journals Measures Derived from Panoramic Ultrasonography and Animal-Based Protein Intake Are Related to Muscular Performance in Middle-Aged Adults

2021 ◽  
Vol 10 (5) ◽  
pp. 988
Author(s):  
Nathaniel R. Johnson ◽  
Christopher J. Kotarsky ◽  
Kyle J. Hackney ◽  
Kara A. Trautman ◽  
Nathan D. Dicks ◽  
...  
Keyword(s):  
Protein Intake ◽  
Handgrip Strength ◽  
Muscle Size ◽  
Dietary Intakes ◽  
Lower Body ◽  
Linear Regression Models ◽  
Middle Aged ◽  
Cross Sectional ◽  
Muscular Performance ◽  
Middle Aged Adults

Ultrasonography advantageously measures skeletal muscle size and quality, but some muscles may be too large to capture with standardized brightness mode (B-mode) imaging. Panoramic ultrasonography can capture more complete images and may more accurately measure muscle size. We investigated measurements made using panoramic compared to B-mode ultrasonography images of the rectus femoris with muscular performance. Concurrently, protein intake plays an important role in preventing sarcopenia; therefore, we also sought to investigate the association between animal-based protein intake (ABPI) and muscular performance. Ninety-one middle-aged adults were recruited. Muscle cross-sectional area (CSA) and thickness were obtained using B-mode and panoramic ultrasound and analyzed with Image J software. Muscular performance was assessed using isokinetic dynamometry, a 30-s chair test, and handgrip strength. Three-day food diaries estimated dietary intakes. Linear regression models determined relationships between measures from ultrasonography and muscular performance. Mixed linear models were used to evaluate the association between ABPI and muscular performance. Muscle CSA from panoramic ultrasonography and ABPI were positively associated with lower-body strength (β ± S.E.; CSA, 42.622 ± 20.024, p = 0.005; ABPI, 65.874 ± 19.855, p = 0.001), lower-body endurance (β ± S.E.; CSA, 595 ± 200.221, p = 0.001; ABPI, 549.944 ± 232.478, p = 0.020), and handgrip strength (β ± S.E.; CSA, 6.966 ± 3.328, p = 0.004; ABPI, 0.349 ± 0.171, p = 0.045). Panoramic ultrasound shows promise as a method for assessing sarcopenia. ABPI is related to better muscular performance.

Muscle volume vs. anatomical cross-sectional area: different muscle assessment does not affect the muscle size-strength relationship

2022 ◽  
pp. 110956
Author(s):  
Marcel B. Lanza ◽  
Hugo C. Martins-Costa ◽  
Carolina C. De Souza ◽  
Fernando V. Lima ◽  
Rodrigo C. Diniz ◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Muscle Volume ◽  
Muscle Size ◽  
Sectional Area ◽  
Cross Sectional ◽  
Strength Relationship

A semi-automated measurement of muscle fiber size using the Imaris software

2021 ◽  
Author(s):  
Jennifer E. Gilda ◽  
Joon-Hyuk Ko ◽  
Aviv-Yvonne Elfassy ◽  
Nadav Tropp ◽  
Anna Parnis ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Muscle Fiber ◽  
Cross Sections ◽  
Statistical Tests ◽  
Muscle Fibers ◽  
Fluorescent Labeling ◽  
Cross Sectional ◽  
Short Period ◽  
Fiber Size ◽  
Specific Protease

The size and shape of skeletal muscle fibers are affected by various physiological and pathological conditions, such as muscle atrophy, hypertrophy, regeneration, and dystrophies. Hence, muscle fiber cross-sectional area (CSA) is an important determinant of muscle health and plasticity. We adapted the Imaris software to automatically segment muscle fibers based on fluorescent labeling of the plasma membrane, and measure muscle fiber CSA. Analysis of muscle cross sections by the Imaris semi-automated and manual approaches demonstrated a similar decrease in CSA of atrophying muscles from fasted mice compared with fed controls. In addition, we previously demonstrated that downregulation of the Ca2+-specific protease calpain-1 attenuates muscle atrophy. Accordingly, both the Imaris semi-automated and manual approaches showed a similar increase in CSA of fibers expressing calpain-1 shRNA compared with adjacent non-transfected fibers in the same muscle cross section. Although both approaches seem valid for measurements of muscle fiber size, the manual marking method is less preferable because it is highly time-consuming, subjective, and limits the number of cells that can be analyzed. The Imaris semi-automated approach is user-friendly, requires little training or optimization, and can be used to efficiently and accurately mark thousands of fibers in a short period of time. As a novel addition to the commonly used statistics, we also describe statistical tests that quantify the strength of an effect on fiber size, enabling detection of significant differences between skewed distributions that would otherwise not be detected using typical methods.

Skeletal Muscle Adaptations to Prolonged Exposure to Extreme Altitude: A Role of Physical Activity?

2008 ◽  
Vol 9 (4) ◽  
pp. 311-317 ◽  
Author(s):  
Masao Mizuno ◽  
Gabrielle K Savard ◽  
Nils-Holger Areskog ◽  
Carsten Lundby ◽  
Bengt Saltin
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Prolonged Exposure ◽  
Muscle Adaptations ◽  
Extreme Altitude ◽  
Skeletal Muscle Adaptations

scholarly journals Training program-induced skeletal muscle adaptations in two men with myotonic dystrophy type 1

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Marie-Pier Roussel ◽  
Marika Morin ◽  
Mélina Girardin ◽  
Anne-Marie Fortin ◽  
Mario Leone ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Training Program ◽  
Myotonic Dystrophy ◽  
Myotonic Dystrophy Type 1 ◽  
Myotonic Dystrophy Type ◽  
Muscle Adaptations ◽  
Skeletal Muscle Adaptations

Mechanisms leading to restoration of muscle size with exercise and transplantation after spinal cord injury

2000 ◽  
Vol 279 (6) ◽  
pp. C1677-C1684 ◽  
Author(s):  
Esther E. Dupont-Versteegden ◽  
René J. L. Murphy ◽  
John D. Houlé ◽  
Cathy M. Gurley ◽  
Charlotte A. Peterson
Keyword(s):  
Spinal Cord ◽  
Satellite Cell ◽  
Fiber Type ◽  
Cell Activity ◽  
Muscle Size ◽  
Spinal Cord Tissue ◽  
Cellular Mechanisms ◽  
Cross Sectional ◽  
Cord Injury ◽  
Nuclear Number

We have shown that cycling exercise combined with fetal spinal cord transplantation restored muscle mass reduced as a result of complete transection of the spinal cord. In this study, mechanisms whereby this combined intervention increased the size of atrophied soleus and plantaris muscles were investigated. Rats were divided into five groups ( n = 4, per group): control, nontransected; spinal cord transected at T10 for 8 wk (Tx); spinal cord transected for 8 wk and exercised for the last 4 wk (TxEx); spinal cord transected for 8 wk with transplantation of fetal spinal cord tissue into the lesion site 4 wk prior to death (TxTp); and spinal cord transected for 8 wk, exercised for the last 4 wk combined with transplantation 4 wk prior to death (TxExTp). Tx soleus and plantaris muscles were decreased in size compared with control. Exercise and transplantation alone did not restore muscle size in soleus, but exercise alone minimized atrophy in plantaris. However, the combination of exercise and transplantation resulted in a significant increase in muscle size in soleus and plantaris compared with transection alone. Furthermore, myofiber nuclear number of soleus was decreased by 40% in Tx and was not affected in TxEx or TxTp but was restored in TxExTp. A strong correlation ( r = 0.85) between myofiber cross-sectional area and myofiber nuclear number was observed in soleus, but not in plantaris muscle, in which myonuclear number did not change with any of the experimental manipulations. 5′-Bromo-2′-deoxyuridine-positive nuclei inside the myofiber membrane were observed in TxExTp soleus muscles, indicating that satellite cells had divided and subsequently fused into myofibers, contributing to the increase in myonuclear number. The increase in satellite cell activity did not appear to be controlled by the insulin-like growth factors (IGF), as IGF-I and IGF-II mRNA abundance was decreased in Tx soleus and plantaris, and was not restored with the interventions. These results indicate that, following a relatively long postinjury interval, exercise and transplantation combined restore muscle size. Satellite cell fusion and restoration of myofiber nuclear number contributed to increased muscle size in the soleus, but not in plantaris, suggesting that cellular mechanisms regulating muscle size differ between muscles with different fiber type composition.

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