Muscle Thickness, Echo-Intensity, Peak Force, Time Under Tension, Total Load Lifted, and Perception of Effort Comparisons Between Two Abdominal Crunch Resistance Training Protocols in Recreationally-Trained Participants.

The primary purpose of this study was to evaluate acute dose response of different intensities with total volume equalized during the abdominal crunch exercise on muscle thickness, echo-intensity, peak force, time under tension, total load lifted, and perception of effort in recreationally-trained participants. Fifteen resistance-trained participants (23 ± 3 years) performed the abdominal crunch exercise in one of two different resistance training (RT) protocols in a randomized order: RT4×10RM (4 sets of 10RM / 1-min rest) or RT1×40RM (1 set of 40RM). Muscle thickness (MT), echo-intensity (EI), peak force (PF), time under tension (TUT), total load lifted (TLL), and session rating of perceived exertion (sRPE) were measured pre-test and post-test (0-min and 15-min). Two-way repeated-measures ANOVAs (2 × 3) were used to test differences between RT protocols (RT4×10RM and RT1×40RM) and time (pre-test, post-0, and post-15) for MT, EI, and PF. Paired t-test was used to compare RT protocols for sRPE, TLL, and TUT. For MT, there were significant differences for RT4×10RM between pre-x post-0 (p = 0.011), pre-x post-15 (p < 0.001), and post-0 × post-15 (p = 0.02); and for RT1×40RM between pre-x post-0 (p < 0.001) and pre-x post-15 (p = 0.003). For EI, there was a significant difference for RT4×10RM between pre-x post-0 (p = 0.002). For sRPE, there was no significant difference between RT protocols. For TLL and TUT, there were significant differences between RT protocols (p < 0.05). In conclusion, both RT protocols (RT4×10RM and RT1×40RM) induced similar increases in MT but not for EI. TLL and TUT were higher for RT4×10RM. PF and sRPE were similar between RT protocols.

Exercise Variability Did Not Affect Muscle Thickness and Peak Force for Elbow Flexors After a Resistance Training Session in Recreationally-Trained Subjects.

The purpose of this study is to measure the acute effects of exercise variability on muscle thickness and physical performance after two resistance training (RT) protocols using the same or different exercises in recreationally-trained subjects. Fifteen resistance-trained men (23.1 ± 2.6 years, 83.4 ± 16.6 kg, 173.5 ± 8.3cm) performed one of two RT protocols: SINGLE: six sets of 10RM/two-minutes rest of the unilateral biceps curl exercise using cables or MIX: six sets of 10RM/two-minutes rest for the unilateral biceps curl exercises (cable: three sets and dumbbells: three sets, randomly). Muscle thickness (MT) and peak force (PF) were measured ten-minutes before (control), pre-RT session, and post-RT (immediately after and 15-minutes after). All acute RT variables were measured during both RT protocols: the maximal number of repetitions (MNR), the total number of repetitions (TNR), time under tension (TUT), and rating of perceived exertion (RPE). Two-way ANOVA (2 x 4) was used to test differences between RT protocol (SINGLE and MIX) and time (control, pre-test, post0, and post15) for MT and PF. Two-way ANOVAs (2 x 6) were used to test differences between RT protocol (SINGLE and MIX) and sets for MNR, RPEset, and TUT. For PF and MT, there were significant differences in time for both RT protocols (p < 0.05), however, there were not statistical differences between RT protocols. For MNR, RPEset, and TUT, there were significant differences in time (p < 0.05), however, there were not statistical differences between RT protocols. In conclusion, both RT protocols induced a similar increase in MT for elbow flexors and a reduction in peak force.

Different Barbell Height Positions Affect Maximal Isometric Deadlift Force and Subsequent Squat Jump Performance in Recreationally-Trained Men.

The primary purpose of this study is to examine the effect of two different deadlift barbell height positions on maximal isometric force and subsequent maximal squat jump performance in recreationally-trained men. Fifteen young, healthy, recreationally-trained men (age: 24.7 ± 3.5years, height: 177.1 ± 7.9cm, and total body mass: 81.2 ± 9.8kg) volunteered to participate. All participants performed maximal squat jumps (MSJ) at 90° of knee flexion before (pre-test) and after 4-min (post-test) performing the deadlift exercise using maximal isometric force (MIF) and MIF normalized by body mass (ratioMIF) in two barbell height positions (25% and 75% of the lower limb height, LLH) in a randomized and counterbalanced order. A paired-sample t-test was used to test differences in MIF and ratioMIF between 25% LLH and 75% LLH. Two-way ANOVAs were used for positions (25% LLH and 75% LLH) and time (pre- and post-test) for all dependent variables with an alpha of 5%. Differences were found for MIF and ratioMIF during the deadlift between 25% LLH and 75% LLH (p < 0.001). There was observed an increase in impulse between pre- and post-test only at 75% LLH (p < 0.001), decrease in time to peak force between pre- and post-test only at 75% LLH (p < 0.001), and increase in peak force between pre- and post-test at 75% LLH (p = 0.029). The present results showed that the maximal isometric deadlift exercise at 75% LLH (midthigh) improves subsequent jump performance of the squat jump recreationally-trained men.