Sentences with phrase «muscle fascicle»

In most studies in untrained subjects, measurements of muscle fascicle length have been taken in the front thigh, predominantly the vastus lateralis (Reeves et al. 2003; Alegre et al. 2006; Blazevich et al. 2007; Seynnes et al. 2007; Reeves et al. 2009; Erskine et al. 2010; Raj et al. 2011; Guilhem et al. 2012; Scanlon et al. 2013; Baroni et al. 2013; McMahon et al. 2014) and rectus femoris (Scanlon et al. 2013; Baroni et al. 2013) and only a minority of measurements have been taken in other lower body muscles, such as the gastrocnemius (Duclay et al. 2009; Raj et al. 2011), biceps femoris (Potier et al. 2009).

The extent to which muscle fascicle rotation occurs seems to increase with increasing PA (Brainerd & Azizi, 2005; Azizi & Brainerd, 2007; Shin et al. 2009), with increasing muscle contraction velocity (Azizi et al. 2008; Randhawa et al. 2013; Azizi & Roberts, 2013), and with increasing muscle force at similar movement speeds (Randhawa et al. 2013).

Currently, the gold standard method for estimating muscle fascicle lengths for individual muscles is to measure them in cadavers with callipers and this approach is still used to validate more modern methods involving scans (Kellis et al. 2009; Noorkoiv et al. 2010; Ando et al. 2014).

The effect of this change in muscle fascicle PA during muscular contractions is to produce muscle fascicle rotation, which seems to have the effect of counteracting the potentially detrimental effects of increasing PA on muscle contraction velocity (Wakahara et al. 2013).

Indeed, some researchers have observed that muscle fascicle length tends to be longer in elite 100m sprinters than long - distance runners as well as in less - well - trained sprinters (Kumagi et al. 1985; Abe et al. 2001; Lee & Plaza, 2009), although this has not always been reported (Methenitis et al. 2015) and when it comes to certain sports, the relationship may of course be muscle - specific, depending on the contribution of the muscle being investigated to performance in that sport.

Muscle fascicle lengths are associated with superior performance in some sports that require high velocity movements.

Muscle fascicle lengths increase after resistance training programs.

Muscle fascicle rotation during muscular contractions causes muscle contraction velocity to exceed the muscle fiber contraction velocity (Zuurbier & Huijing, 1992; Wakahara et al. 2013).

Morse et al. (2008) found that PCSA was substantially smaller in the gastrocnemius of boys compared to adult males, but PA and muscle fascicle length relative to muscle length did not differ.

Recently, Fukutani & Kurihara (2015) compared PA and muscle fascicle lengths between resistance - trained and untrained individuals.

Kubo et al. (2014) also found no differences in muscle fascicle length relative to muscle length for the medial gastrocnemius between boys and adult males.

Studies exploring isometric training at different muscle lengths have identified differences in regional hypertrophy between training groups, but not always in muscle fascicle length (Noorkõiv et al. 2014).

It is possible that the different regional hypertrophy observed after training at long or short muscle lengths could in fact be closely related to the changes in muscle fascicle length, because changes in muscle fascicle length have been linked to greater increases in muscle size in the distal regions of the muscle (Franchi et al. 2014).

In the long muscle length group, muscle fascicle lengths increased 23 ± 5 %, while in the short muscle length group, muscle fascicle length only increased by 10 ± 2 % over the same period.

Some studies have compared the effects of different types of strength training on the change in muscle fascicle length.

This is expected, because energy storage is the area under the stress - strain curve, and eccentric training increases muscle fascicle length.

Eccentric hamstrings strength and muscle fascicle length are key predictors of increased hamstrings strain injury risk.

Both exercises produced gains in muscle fascicle length.

On the other hand, regional hypertrophy (but not always muscle fascicle length) seems more important than changes in joint angle - specific neural drive for the joint angle - specific gains in strength after isometric training at long muscle lengths (Alegre et al. 2014; Noorkõiv et al. 2014).

Increases in muscle fascicle length are known to occur after training at long muscle lengths (McMahon et al. 2014a), and this may lead to us observing greater increases in regional muscle size (Franchi et al. 2014).

Comparing the effects of eccentric training at long and short muscle lengths, Guex et al. (2016) found that muscle fascicle length increased in both groups, but the increase was greater in the group that trained at long muscle lengths than in the group that trained at short muscle lengths (9.3 % vs. 4.9 %).

Interestingly, the Nordic curl produces greater increases in muscle fascicle length and preferential biceps femoris (short head) and semitendinosus hypertrophy compared to hip extension - based hamstrings exercises (Bourne et al. 2016).

This suggests that increases in muscle fascicle length are partly responsible for the change in the angle of peak torque after strength training, although other factors are likely involved.

Thus, these studies suggest that the length of the muscle during strength training may not be an important factor for altering muscle fascicle length, at least when using isometric contractions.

Eccentric training is a very popular training tool for athletes, because it is very effective for producing large gains in maximum strength, increasing muscle fascicle lengths, and reducing the risk of muscle strain injury.

This specificity is likely attributable to differences in regional hypertrophy (which may be a function of different increases in muscle fascicle length) and joint angle - specific changes in neural drive, just like partial and full range of motion training.

Eccentric training is very effective for increasing eccentric strength, for increasing muscle fascicle length, and also for increasing the ability of muscles to absorb energy while lengthening.

Noorkõiv et al. (2015) reported that both groups increased muscle fascicle length similarly.

Gains in energy absorption capability are moderate - to - strongly (r = 0.59) associated with increases in joint range of motion (Kay et al. 2016), which suggests a connection between increases in energy storage and an increase in muscle fascicle length.

Eccentric training increases eccentric strength very effectively, and also increases muscle fascicle lengths.

Moreover, there was a moderate correlation between the change in muscle fascicle length and the change in the angle of peak torque when measured concentrically (r = 0.57) but not when measured eccentrically (r = 0.17).

The reason for the difference between the changes in joint angle - specific strength and the changes in joint angle - specific neural drive is that both peripheral and central factors are operating, and the impact of joint angle - specific neural drive is greater after training at short muscle lengths, while the impact of peripheral factors (like regional muscle size and / or muscle fascicle length) are greater after training at long muscle lengths.

However, increases in muscle fascicle length are also likely dependent on the mechanical load incurred by the prime mover, as knee flexion (hamstring only) exercise seems to lead to greater adaptations in the hamstrings than hip extension (hamstring, gluteus maximus, and adductor magnus) exercise, even when muscle length at peak contraction is shorter (Bourne et al. 2016).

The addition of sarcomeres in series (and muscle fascicle length) after eccentric training may lead to greater increases in distal muscle size.

However, the effect of changing muscle fascicle length on eccentric - specific strength is less clear.

The increases in muscle fascicle length seem to be affected by the amount of stretch during training, because training at longer muscle lengths leads to greater adaptations (Guex et al. 2016).

Muscle fascicle length increases more after eccentric training than after concentric training (Ema et al. 2016), probably through a larger increase in the number of sarcomeres in series within the myofibrils of a muscle fiber (Brughelli & Cronin, 2007; Butterfield, 2012).

Thus, increasing muscle fascicle length will mean that you record a lower value of stiffness, even if the individual muscle fibers are themselves now made of stiffer material.

Muscle pennation angle is much less easy to get a handle on than muscle fascicle length.

Increasing muscle fascicle length through eccentric training could therefore be a valuable method for improving athletic performance in high - velocity movements, such as sprinting.

On the other hand, increasing muscle fascicle length through eccentric training seems to be a disadvantage for changes in rate of force development (RFD), probably because it causes a decrease in muscle stiffness (Kay et al. 2016).

Increasing muscle fascicle length through eccentric training could therefore be a valuable method for improving athletic performance in movements that have peak contractions at long muscle lengths, such as the terminal swing phase of sprinting, or the ground contact phase of sharp change of direction (COD) maneuvers.

In summary, it seems likely that the increases in muscle fascicle length that happen as a result of eccentric training lead to greater increases in high - velocity strength, smaller increases in RFD, and greater increases in strength at long muscle lengths (by a shift in the optimum angle).

An emphasis on increasing muscle fascicle length rather than pennation angle may therefore be beneficial for both eccentric and concentric strength, in comparison with concentric training.

Pennated muscle fascicles actually rotate during contractions, which reduces the effective pennation angle (Brainerd & Azizi, 2005), and the amount of rotation is greater in faster contractions (Azizi et al. 2008).

Around muscles, around muscle fascicles, and around muscles themselves is an extracellular matrix (ECM) made of different types of collagen, which is very stiff.

The medial and lateral gastrocnemius muscles display longer muscle fascicles than the soleus.

Greater muscle size is helpful for increasing high - velocity strength, as larger, stronger muscle fascicles are able to produce more force.

The rectus abdominis displays the greatest muscle thickness, the longest muscle fascicles, but the smallest pennation angle.

Muscle fascicles are themselves wrapped around by the perimysium and are comprised of many muscle fibers, which do not always run the length of the muscle fascicle that contains them (Sokoloff & Goslow, 1999).