Barbosa, GM, Trajano, GS, Dantas, GAF, Silva, BR, and Vieira, WHB. Chronic effects of static and dynamic stretching on hamstrings eccentric strength and functional performance: A randomized controlled trial. J Strength Cond Res 34(7): 2031–2039, 2020—The purpose of this study was to investigate the effect of static or dynamic stretching training program on hamstrings eccentric peak torque and functional performance. Forty-five active healthy men were randomly allocated into 3 groups (n = 15 per group): no stretching (control), static stretching (3 sets of 30 seconds), and dynamic stretching (3 sets of 30 repetitions). Static and dynamic stretching protocols on the hamstring muscles were performed 3 times a week until complete 10 sessions. Isokinetic knee flexor eccentric peak torque (60°·s−1), triple hop distance, and modified 20-m sprint time were assessed in a random order before and after stretching training. A mixed-design analysis of variance was performed, with an alpha level of 0.05. There was a significant decrease of eccentric peak torque (p ≤ 0.0001, −15.4 ± 10.4%, within-group effect size: 1.03) after static stretching training. The static stretching training reduced eccentric torque when compared with no stretching (−7.6 ± 21.7%, between-group effect size: 0.50) and dynamic stretching (−7.8 ± 29.8%, between-group effect size: 0.51). Moreover, the reached distance on triple hop test was also reduced after static stretching protocol (p = 0.009, −3.7 ± 4.1%, within-group effect size: 0.29). These findings suggest that static stretching training is sufficient to produce meaningful reductions on hamstrings eccentric torque and functional performance. Based on the results of this study, caution should be taken when prescribing of static stretching training in isolation when the purpose is to improve performance, and indirectly, to prevent hamstring strain injuries due to its possible negative effects on hopping performance and knee flexor eccentric torque.

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This study aims to investigate the effect of melatonin on activation, growth and morphology of bovine primordial follicles, as well as on stromal cells density in ovarian tissues after in vitro culture. Ovarian fragments were cultured in α‐MEM+ alone or supplemented with melatonin (250, 500, 1,000 or 2,000 pM) for a period of six days. Non‐cultured and cultured tissues were processed for histological analysis; according to developmental stages, follicles were classified as primordial or growing follicles. These follicles were further classified as morphologically normal or degenerated. Ovarian stromal cell density was also evaluated. The percentages of primordial and developing follicles, as well as those classified of normal follicles, were compared by Fisher's exact test, and the differences were considered significant when p < .05. The results showed that the presence of 1,000 and 2,000 pM melatonin in culture medium promoted a reduction in the percentage of primordial follicles and an increase in the percentage of development follicles, when compared to follicles cultured in control medium. On the other hand, the presence of 250 or 500 pM melatonin did not show a significant effect on the percentage of primordial and developing follicles. Besides that, the presence of 500, 1,000 and 2,000 pM melatonin maintained the percentage of normal follicles similar to those seen uncultured control. Moreover, tissues cultured in presence of 1,000 pM melatonin showed a higher percentage of normal follicles when compared to follicles cultured in the presence of 250 pM melatonin. It was observed a similar profile of stromal density in both uncultured tissues and those cultured in vitro in the presence of melatonin. In conclusion, melatonin (1,000 and 2,000 pM) promotes bovine primordial follicles activation and maintains the stromal cell density during in vitro culture of ovarian cortical tissue.

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Assisted reproductive technology (ART) have contributed to preserve fertility in humans and to increase multiplication of genetically superior animals. Despite being highly practiced worldwide, ART presents some challenges, especially because gametes and embryos are kept in vitro for a variable period of time, and the oxidative stress in vitro can have negative impact on oocyte competence and embryo development. Nanotechnology needs to be considered to help overcome some of those impairments, since it can provide strategies to deliver antioxidants and hormones to gametes and embryos in vitro. The application of nanotechnology to ART can allow the development of new protocols using nanomaterials to improve in vitro oocyte competence and embryo production. This review discusses the applicability of nanomaterials to improve sperm selection, to deliver antioxidants and hormones to preantral follicles, oocytes, and embryos in vitro, as well as the concerns about using nanotechnology in ART.

This study evaluated the effects of epidermal growth factor (EGF) and progesterone (P4) on growth, the resumption of meiosis and expression of eukaryotic translation initiation factor 4E(eIF4E), poly(A)-specific ribonuclease (PARN), oocyte-specific histone H1 (H1FOO), oocyte maturation factor Mos (cMOS), growth differentiation factor-9 (GDF9) and cyclin B1 (CCNB1) mRNA in oocytes from small and medium-sized antral follicles after prematuration and maturation invitro. Oocytes from small (&lt;2.0mm) and medium (3.0–6.0mm) antral follicles were cultured in medium containing EGF (10ng mL–1), P4 (100 µM) or both. After culture, growth rate, resumption of meiosis and eIF4E, PARN, H1FOO, cMOS, GDF9 and CCNB1 mRNA levels were evaluated. P4 increased cMOS, H1FOO and CCNB1 mRNA levels after the culture of oocytes from small antral follicles, and EGF increased CCNB1 mRNA levels in these oocytes. In the medium-sized antral follicles, P4 alone or in combination with EGF increased oocyte diameter after prematuration invitro. In these oocytes, the presence of either EGF or P4 in the culture medium increased cMOS mRNA levels. In conclusion, P4 increases cMOS, H1FOO and CCNB1 mRNA levels after the culture of oocytes from small antral follicles. P4 and the combination of EGF and P4 promote the growth of oocytes from medium-sized antral follicles, and both EGF and P4 increase cMOS mRNA levels.

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This study evaluates the levels of messenger RNA (mRNA) for eIF4E, PARN, H1FOO, cMOS, GDF9, and CCNB1 in oocytes from secondary and antral follicles at different stages of development. The effects of in vitro culture, in vitro prematuration, and in vitro maturation on the expression of these genes on oocytes were also analyzed. The results showed that mRNA levels for H1FOO, GDF9, and PARN were higher in oocytes from small, medium, and large antral follicles, respectively, than those seen in secondary follicles. Oocytes from small, medium, and large antral follicles had higher levels of CCNB1 than oocytes from secondary follicles. Oocytes from cultured secondary follicles had higher levels of GDF9, CMOS, PARN, eIF4E, CCNB1, and H1FOO than before culture. Prematured oocytes from small antral follicles had higher levels of mRNA for GDF9, PARN, and eIF4E than before culture. In addition, higher levels of cMOS and H1FOO were identified in prematured oocytes from medium antral follicles. In conclusion, follicular growth is associated with an increase in the expression of H1FOO, GDF9, CCNB1, and PARN. The culture of secondary follicles, prematuration, and maturation of oocytes from antral follicles increase the expression of eIF4E, PARN, H1FOO, cMOS, GDF9, and CCNB1.