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Camila Ximenes Santos, Natália Barros Beltrão, André Luiz Torres Pirauá, João Luiz Quagliotti Durigan, David Behm and Rodrigo Cappato de Araújo

effects of stretch intensity versus duration. According to Weppler and Magnusson, 11 an understanding of neuromuscular ROM gains should include passive torque measurements and muscle architecture. Regarding muscle architecture, some studies used ultrasound to evaluate acute adaptations of static

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Diego Alonso-Fernandez, Yaiza Taboada-Iglesias, Tania García-Remeseiro and Águeda Gutiérrez-Sánchez

type of exercises that do not require expensive equipment and are easy to apply, based on their effects on muscle architecture. The most studied is the Nordic Hamstring exercise, due to its effects on the hamstring muscles, is one of the most susceptible to injuries within the sport movement. 7 , 19

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Wolfgang Seiberl, Daniel Hahn, Florian Kreuzpointner, Ansgar Schwirtz and Uwe Gastmann

The purpose of this study was to investigate if force enhancement (FE) in vivo is influenced by stretch-induced changes of muscle architecture. Therefore, 18 subjects performed maximum voluntary isometric (100° knee flexion angle) and isometric-eccentric-isometric stretch contractions (80°–100° ω = 60°s−1) whereby pennation angle and fascicle length of vastus lateralis was determined using ultrasonography. We found significant (2-way repeated ANOVA; α = 0.05) enhanced torque of 5–10% after stretch as well as significant passive FE but no significant differences in muscle architecture between isometric and stretch contractions at final knee angle. Furthermore, EMG recordings during a follow-up study (n = 10) did not show significant differences in activation and mean frequency of contraction conditions. These results indicate that FE in vivo is not influenced by muscle architectural changes due to stretch.

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Christina C.P. Cepeda, Angélica Lodovico, Neil Fowler and André L.F. Rodacki

Aging is related to a progressive remodeling of the neuromuscular system, which includes muscle mass, strength, and power reductions. This study investigated the effect of an eight-week dance program on fascicle pennation angle, fascicle length, and thickness of the vastus lateralis (VL), tibialis anterior (TA), biceps femoris (BF), and gastrocnemius medialis (GM) muscles using ultrasound images. Thirty-four healthy older women were randomly assigned to either a dancing (DG: n = 19, 69.1 ± 6.5 years, 72.5 ± 11.7 kg) or control group (CG: n = 15, 71.5 ± 7.4 years, 70.9 ± 9.3 kg). After training, the DG showed greater (p < .05) thickness for VL (16%), TA (17%), BF (19%), and GM (15%); pennation angle for VL (21%), TA (23%), BF (21%), and GM (17%); and fascicle length for VL (11%), TA (12%), BF (10%), and GM (10%). These findings suggest that dance training was effective to change the lower limb muscle architecture in older female adults.

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Taku Wakahara, Hiroaki Kanehisa, Yasuo Kawakami, Tetsuo Fukunaga and Toshimasa Yanai

The purpose of this study was to examine the relationship between muscle architecture of the triceps brachii (TB) and joint performance during concentric elbow extensions. Twenty-two men performed maximal isometric and concentric elbow extensions against various loads. Joint torque and angular velocity during concentric contractions were measured, and joint power was calculated. Muscle length, cross-sectional areas, and volume of TB were measured from magnetic resonance images. Pennation angle (PA) of TB at rest was determined by ultrasonography. The PA was significantly correlated with the maximal isometric torque (r = .471), but not to the torque normalized by muscle volume (r = .312). A significant correlation was found between PA and the angular velocity at 0 kg load (r = .563), even when the angular velocity was normalized by the muscle length (r = .536). The PA was significantly correlated with the maximal joint power (r = .519), but not with the power normalized by muscle volume (r = .393). These results suggest that PA has a positive influence on the muscle shortening velocity during an unloaded movement, but does not have a significant influence on the maximum power generation in untrained men.

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Daniel E. Lidstone, Justin A. Stewart, Reed Gurchiek, Alan R. Needle, Herman van Werkhoven and Jeffrey M. McBride

prolonged load carriage may therefore result in changes in muscle architecture. Increased fascicle lengths following repetitive fatiguing contractions has been shown to be related to reductions in maximal force. 17 The combined effects of heavy loads carried by soldiers and repetitive eccentric loading

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Live S. Luteberget, Truls Raastad, Olivier Seynnes and Matt Spencer

Fast acceleration is an important performance factor in handball. In addition to traditional sprint training (TST), resisted-sprint training (RST) is a method often used to improve acceleration. However, studies on RST show conflicting results, and underlying mechanisms have not been studied.

Purpose:

To compare the effects of RST, by sled towing, against TST on sprint performance and muscle architecture.

Methods:

Participants (n = 18) were assigned to either RST or TST and completed 2 training sessions of RST or TST per week (10 wk), in addition to their normal team training. Sprint tests (10 and 30 m) and measurements of muscle architecture were performed pre- and posttraining.

Results:

Beneficial effects were found in the 30-m-sprint test for both groups (mean; ±90% CL: TST = −0.31; ±0.19 s, RST = −0.16; ±0.13 s), with unclear differences between the groups. Only TST had a beneficial effect on 10-m time (−0.04; ±0.04 s), with a likely difference between the 2 groups (85%, ES = 0.60). Both groups had a decrease in pennation angle (−6.0; ±3.3% for TST and −2.8; ±2.0% for RST), which had a nearly perfect correlation with percentage change in 10-m-sprint performance (r = .92). A small increase in fascicle length (5.3; ±3.9% and 4.0; ±2.1% for TST and RST, respectively) was found, with unclear differences between groups.

Discussion:

TST appears to be more effective than RST in enhancing 10-m-sprint time. Both groups showed similar effects in 30-m-sprint time. A similar, yet small, effect of sprint training on muscle architecture was observed in both groups.

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Yasuo Kawakami and Tetsuo Fukunaga

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Bruno Manfredini Baroni, Jeam Marcel Geremia, Rodrigo Rodrigues, Marcelo Krás Borges, Azim Jinha, Walter Herzog and Marco Aurélio Vaz

It is not known if a physically active lifestyle, without systematic training, is sufficient to combat age-related muscle and strength loss. Therefore, the purpose of this study was to evaluate if the maintenance of a physically active lifestyle prevents muscle impairments due to aging. To address this issue, we evaluated 33 healthy men with similar physical activity levels (IPAQ = 2) across a large range of ages. Functional (torque-angle and torque-velocity relations) and morphological (vastus lateralis muscle architecture) properties of the knee extensor muscles were assessed and compared between three age groups: young adults (30 ± 6 y), middle-aged subjects (50 ± 7 y) and elderly subjects (69 ± 5 y). Isometric peak torques were significantly lower (30% to 36%) in elderly group subjects compared with the young adults. Concentric peak torques were significantly lower in the middle aged (18% to 32%) and elderly group (40% to 53%) compared with the young adults. Vastus lateralis thickness and fascicles lengths were significantly smaller in the elderly group subjects (15.8 ± 3.9 mm; 99.1 ± 25.8 mm) compared with the young adults (19.8 ± 3.6 mm; 152.1 ± 42.0 mm). These findings suggest that a physically active lifestyle, without systematic training, is not sufficient to avoid loss of strength and muscle mass with aging.

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Annika Kruse, Christian Schranz, Martin Svehlik and Markus Tilp

pooled data did not show alterations in gastrocnemius fascicle length ( F 2,42  = 0.603, P  = .55, η p 2 = .028 ), pennation angle ( F 2,42  = 2.523, P  = .09, η p 2 = .107 ), and thickness ( χ 2 [ 2 ] = 0.217 , P  = .90). Figure 2 —Mean and SD of the GM (A, B, and C) and VL (D) muscle architecture