The purpose of this study was to examine the effects of dynamic stretching on the passive biomechanical properties and isometric muscle strength of the knee flexors. Fourteen healthy men (mean ± s: age = 24 ± 3 years) performed passive range of motion assessments and isometric maximal voluntary contractions of the knee flexors at knee joint angles of 35°, 50°, 65°, 80°, and 95° below full knee extension before and after dynamic stretching. In addition, electromyographic amplitude was recorded from the biceps femoris during the maximal voluntary contractions. Passive stiffness and passive resistive torque were measured during pre- and post-dynamic stretching. The dynamic stretching included the participant extending their right leg outwards to the end range motion and pulling their leg back towards the body while seated in the isokinetic dynamometer for four 30-s bouts with 20-s rest between bouts. Passive range of motion increased while passive stiffness and passive resistive torque decreased following dynamic stretching. Peak torque decreased at knee joint angles of 65° and 80° below full extension, while electromyographic amplitude decreased following dynamic stretching. Dynamic stretching resulted in changes to passive stiffness and passive resistive torque that are typically reported following static stretching, however, there were decreases in peak torque at two of the knee joint angles.

Body mass = 64.5 ± 9.3 kg, height = 164.7 ± 6.5 cm) performed maximal voluntary isokinetic leg extension, flexion, and eccentric hamstring muscle actions at the angular velocities of 60°·s−1 and 180°·s−1 before and after a bout of dynamic hamstring and quadriceps stretching as well as a control condition. Results Leg flexion peak torque decreased under both control (mean ± SE for 60°·s−1 = 75.8 ± 4.0 to 72.4 ± 3.7 N·m, 180°·s−1 = 62.1 ± 3.2 to 59.1 ± 3.1 N·m) and stretching (60°·s−1 = 73.1 ± 3.9 to 65.8 ± 3.3 N·m, 180°·s−1 = 61.2 ± 3.3 to 54.7 ± 2.6 N·m) conditions, whereas eccentric hamstring peak torque decreased only after the stretching (60°·s−1 = 87.3 ± 5.1 to 73.3 ± 3.6 N·m, 180°·s−1 = 89.2 ± 4.4 to 77.0 ± 3.4 N·m) intervention (P ≤ 0.05). Stretching also caused a decrease in conventional H:Q (60°·s−1 = 0.58 ± 0.02 to 0.54 ± 0.02, 180°·s−1 = 0.67 ± 0.02 to 0.61 ± 0.03) and functional H:Q ratios (60°·s−1 = 0.69 ± 0.03 to 0.60 ± 0.03, 180°·s−1 = 1.00 ± 0.06 to 0.60 ± 0.03) (P ≤ 0.05). Conclusions Because dynamic stretching reduced concentric and eccentric hamstring strength as well as the conventional and functional H:Q ratios, fitness and allied-health professionals may need to be cautious when recommending dynamic rather than static stretching to maintain muscle force....

The purpose of this study was to examine the effects of 2 different types of protein supplementation on thigh muscle cross-sectional area (CSA), blood markers, muscular strength, endurance, and body composition after 8 weeks of low- or moderate-volume resistance training in healthy, recreationally trained, college-aged men. One hundred and six men were randomized into 5 groups: low-volume resistance training with bioenhanced whey protein (BWPLV; n = 22), moderate-volume resistance training with BWP (BWPMV; n = 20), moderate-volume resistance training with standard whey protein (SWPMV; n = 22), moderate-volume resistance training with a placebo (PLA; n = 21), or moderate-volume resistance training with no supplementation (CON; n = 21). Except for CON, all groups consumed 1 shake before and after each exercise session and one each on the nontraining day. The BWPLV, BWPMV, and SWPMV groups received approximately 20 g of whey protein per shake, whereas the BWP groups received 5 g of additional polyethylene glycosylated (PEG) leucine. Resistance training sessions were performed 3 times per week for 8 weeks. There were no interactions (p > 0.05) for muscle strength and endurance variables, body composition, muscle CSA, and safety blood markers, but the main effects for training were observed (p ≤ 0.05). However, the Albumin:Globulin ratio for SWPMV was lower (p = 0.037) than BWPLV and BWPMV. Relative protein intake (PROREL) indicated a significant interaction (p < 0.001) with no differences across groups at pre; however, BWPLV, BWPMV, and SWPMV had a greater intake than did PLA or CON at post (p < 0.001). This study indicated that 8 weeks of resistance training improved muscle performance and size similarly among groups regardless of supplementation.

Background: In 2014, Costello and colleagues published a sentinel paper spotlighting the large disparity of female versus male representation within sports science and sports medicine (SSSM) research. Purpose: To (1) revisit the method published by Costello et al a decade later to evaluate female representation and (2) ascertain whether study designs account for menstrual status. Study Design: Systematic Review; Level of evidence, 4. Methods: All original and epidemiologic research of live human participants from the journals Medicine and Science in Sports and Exercise , British Journal of Sports Medicine , and the American Journal of Sports Medicine were included from January 2021 to August 2023. Number of male and female participants for each study was analyzed. A menstrual-status tiering system published by Smith et al was used to classify the consideration of female participants’ menstrual status in study design. Results: A total of 1441 studies and 40,152,860 participants were included in this analysis. This included 17,648,509 (43.95%) female participants. The mean proportion of female participants per study was 40.22%, and 103 (7.15%) studies included only female participants compared with 268 (18.6%) male-only studies. A total of 66 (5.6%) studies included menstrual-status considerations in their study design with 7.7 (0.7%) and 5.5 (0.5%) receiving a silver or gold classification, respectively, for design considerations. Conclusion: Our investigation into the representation of female athletes in SSSM research found an increase in female participation from 39% to 43.95% of total participants over the past decade. While the overall number of female participants rose in the years 2021 to 2023, there remains a significant disparity in female representation in SSSM research compared with male participants. Additionally, we found that the inclusion of menstrual status in study designs has been limited, with few studies considering this crucial variable.