Search

Ultrasonography has been extensively used to evaluate skeletal muscle morphology. The echo intensity, i.e., the mean pixel intensity of a specific region of interest in an ultrasound image, may vary among muscles and individuals with several intramuscular parameters presumed to influence it. The purpose of this study was to investigate the correlation between muscle echo intensity and muscle fiber type composition in humans. Thirteen female physical education students (age: 22.3 ± 5.4 years, height: 1.63 ± 0.06 m, body mass: 59.9 ± 7.4 kg) with no history of systematic athletic training participated in the study. Body composition with dual X-ray absorptiometry, leg-press maximum strength (1-RM), echo intensity, and the cross-sectional area (CSA) of the vastus lateralis (VL) muscle according to ultrasonography were measured. Muscle biopsies were harvested from the VL site where the echo intensity was measured. VL echo intensity was not significantly correlated with the percentage of type I muscle fibers or with the percentage area of type I muscle fibers. However, when VL echo intensity was corrected for the subcutaneous fat thickness at the site of the measurement, it was significantly correlated with the percentage of type I muscle fibers (r = 0.801, p < 0.01) and the percentage area of type I muscle fibers (r = 0.852, p < 0.01). These results suggest that the echo intensity of the vastus lateralis muscle corrected for the subcutaneous fat thickness at the measurement site may provide an estimate of the muscle fiber type composition, at least in young moderately trained females. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present study was to investigate the relationship between weightlifting performance and the rate of force development (RFD), muscle architecture, and body composition in elite Olympic weightlifters. Methods: Six male Olympic weightlifters (age 23.3 [3.4] y, body mass 88.7 [10.2] kg, body height 1.76 [0.07] m, snatch 146.7 [15.4] kg, clean and jerk 179.4 [22.1] kg), all members of the national team, participated in the study. Athletes completed a 16-week periodized training program aiming to maximize their performance at the national competition event. Measurements, including maximal strength (1-repetition maximum) in snatch, clean and jerk, back and front squat, isometric leg press RFD and peak force, countermovement jump, vastus lateralis muscle architecture, and body composition, were performed before and after the training period. Results: Weightlifting performance increased significantly after training (P <.05). Leg press RFD increased only in time windows of 0 to 200 and 0 to 250 milliseconds after training (8.9% [8.5%] and 9.4% [7.7%], respectively, P <.05) while peak force remained unaltered (P <.05). Front squat strength increased significantly (P <.05), while countermovement jump power increased 2.3% (2.1%) (P <.05). No changes were observed for muscle architecture and lean body mass (P >.05). Significant correlations were observed between performance in snatch and clean and jerk with isometric leg press RFD, at all time windows, as well as with lean body mass and squat 1-repetition maximum. Conclusions: These results suggest that regular examination of RFD, lean body mass, and lower extremities' 1-repetition maximum may be useful performance predictors in elite Olympic weightlifters. [ABSTRACT FROM AUTHOR]

Purpose. The study aim was: (a) to investigate the relationship between triceps brachii muscle architecture and upperbody isometric rate of force development (RFD), isometric peak force (IPF), and maximum strength (one-repetition maximum, 1-RM) in bench press and (b) to explore whether triceps brachii architecture might determine RFD, IPF, and 1-RM strength in stronger and weaker participants. Methods. The study involved 21 males (age: 22.6 ± 4.7 years, weight: 76.6 ± 10.2 kg, height: 1.79 ± 0.07 m) with 3.4 ± 2.1 years of experience in resistance training. They were divided into a strong and weak group depending on their relative 1-RM strength in bench press. Measurements included triceps brachii muscle architecture, upper-body isometric RFD, IPF, and 1-RM strength in bench press. Results. Moderate to large correlations were found for triceps brachii thickness and fascicle angle with upper-body RFD (r: 0.379-0.627), IPF (r: 0.582 and 0.564, respectively), and 1-RM strength in bench press (r: 0.530 and 0.412, respectively). Maximum strength in bench press was largely correlated with IPF (r = 0.816); moderate to very large correlations were observed with RFD (r: 0.499-0.725). The strong group presented significantly higher 1-RM relative strength, RFD, and IPF (p < 0.05) than the weak group, but no significant between-group difference was found for triceps brachii architecture (p > 0.05). Conclusions. Triceps brachii architecture correlates with 1-RM strength, upper-body RFD, and IPF in trained participants. However, triceps brachii architecture may not distinguish upper-body strength and RFD between stronger and weaker male participants. [ABSTRACT FROM AUTHOR]

Kelekian, GK, Zaras, N, Stasinaki, AN, Spiliopoulou, P, Karampatsos, G, Bogdanis, G, and Terzis, G. Preconditioning strategies before maximum clean performance in female weightlifters. J Strength Cond Res 36(8): 2318–2321, 2022—The aim of the study was to examine the acute effect of performing clean pulls with either 85% or 120% one repetition maximum (1RM), on subsequent clean performance, in female Olympic weightlifters. Eight competitive female Olympic weightlifters (age, 22.9 ± 5.8 years; height, 1.67 ± 0.06 m; training experience, 6.1 ± 3.9 years; clean performance, 66.3 ± 3.9 kg), performed clean pulls either with 85% or with 120% 1RM, 3 minutes before their maximum effort in clean, in 2 different days, in a counterbalanced order. The rate of perceived exertion (RPE) was provided after each intervention. Body composition (dual x-ray absorptiometry), countermovement jumping (CMJ) performance, leg press isometric rate of force development (RFD), and peak force (PF) were also evaluated on different days. Clean performance was increased by 6.1 ± 3.6% (p = 0.002) after preconditioning with 85% 1RM and 4.7 ± 3.1% (p = 0.004) after 120% 1RM. Rate of perceived exertion was lower after preconditioning with 85% 1RM, compared with 120% 1RM (p = 0.015). No significant correlation was found between the changes in clean performance after 85% or 120% 1RM, with lean body mass, CMJ performance, and isometric leg press RFD, and leg press PF. These data suggest that lifting either 85% or 120% 1RM in clean pulls is an effective strategy for acute increase of clean performance in female Olympic weightlifters, whereas the use of 85% 1RM load may be performed with less exertion. [ABSTRACT FROM AUTHOR]

The purpose of the study was to investigate the effect of seven weeks inter-repetition rest vs. traditional strength training on lower body strength, rate of force development (RFD), and vastus lateralis (VL) muscle architecture. Sixteen male participants were assigned into two groups: the inter-repetition rest (IRRG) and the traditional (TG) group. Both groups performed the leg press exercise with four sets of six maximum repetitions (RM) for two training sessions per week. IRRG added a 20 s inter-repetition rest period between single repetitions. Before and after the training period, 1-RM in leg press, isometric leg press RFD, and peak force (PF), VL muscle architecture, vastus intermedius (VI) thickness, and quadriceps' cross sectional area (CSA) with ultrasonography, were measured. Two way ANOVA for repeated measures was used for statistics. One-RM strength increased similarly for both groups (p < 0.05), while percentage increases in RFD were greater for IRRG compared to TG (p < 0.05). Isometric PF was increased similarly for both groups (p < 0.05). VL and VI thickness as well as CSA of the quadriceps increased similarly in both groups, while VL fascicle length increased more following IRRG compared to TG (IRRG: 4.8 ± 6.1% vs. TG: −3.9 ± 5.4%, p = 0.001). These results suggest that 20 s inter-repetition rest during strength training may effectively increase lower body explosive strength and muscle fascicle length without compromising muscle hypertrophy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present study was to investigate whether a) modification in muscle architecture due to training intervention and b) neuromuscular explosive field tests results may predict competition performance in track and field throwing athletes. Methods: Eleven track and field throwers completed 10 weeks of specific training that was performed prior to the summer official national competition. Before and following the 10 weeks of training programe, track and field throwing trials, vastus lateralis muscle architecture, shot put tests, standing long jump, and 40m sprinting were evaluated. Results: Track and field throwing performance, muscle thickness, fascicle length and power-position shot put throw all increased by 5.78 ± 2.82% (P = 0.000), 6.2 ± 7.4% (P = 0.01), 10.5 ± 13.1% (P = 0.02) and 2.8 ± 3.9% (P = 0.04), respectively. Sprinting time in 40m decreased by -1.2 ± 1.0% (P = 0.004), whilst, work power output during the standing long-jump increased by 1.7 ± 2.5% (P = 0.03) when compared between pre- and post-training intervention. The power-position shot put throwing result was positively correlated with the increase in standing long-jump (r = 0.81, P < 0.01) and with the increase in 40m sprint (r = -0.63, P < 0.05) performances. The increase in muscle thickness was positively correlated with the increase in 40m sprint performance (r = 0.62, P < 0.05). The multiple linear regression analysis, combining the percentage alteration in backward shot put throw and vastus lateralis thickness with the proportional increase in track and field throwing competition performance, explains the 56% increase observed in throwing competition result. Conclusions: These results may suggest that consistent examination of muscle thickness and evaluation of throwing ability using explosive field tests during a training period both may be used to predict the increase in track and field throwing competive performance. [ABSTRACT FROM AUTHOR]

Aim of the study was to investigate the relationship between lower body rate of force development and lean body mass, with competitive shot-put throwing performance in female shot-putters using the linear style. Seven female shot-put athletes (age: 24.4 ± 4.2yrs, body height: 172.8 ± 5.2cm, body mass: 93.3 ± 10.5kg, 4.4 ± 2.0 years of competition experience), who qualified for the final of the shot-put event of the national indoor championship, participated in the study. Three days after the national event, they visited the laboratory to perform maximal isometric leg press for the measurement of the rate of force development (RFD), and maximal countermovement jumps (CMJ), while body composition (dual x-ray absorptiometry) was also evaluated. Shotput performance was recorded from the official results during the national event. Close correlations were found between shot-put performance during competition and RFD between 100-250ms, maximum leg press isometric force, and CMJ power (r: 0.766 - 0.913, p < 0.05). Close correlations were also found between shot-put performance and total (r: 0.932, p < 0.005) and trunk (r: 0.885, p < 0.005) lean body mass (LBM). Lower extremities' LBM was correlated with CMJ max power and RFD between 0-250ms from the onset of muscle contraction (r: 0.834 - 0.905, p < 0.05). These results suggest that monitoring leg press rate of force development, lean body mass and countermovement jumping power may provide important information about performance in female shot-putters who compete with the lineal style. [ABSTRACT FROM AUTHOR]