Effects of In-Season Strength Training on Physical Fitness and Injury Prevention in North African Elite Young Female Soccer Players.

BACKGROUND: Strength training (ST) primarily enhances physical fitness (e.g., muscle strength, power, speed) and bone density in female soccer players. Less information is available on the injury preventive effects of ST in female athletes. Accordingly, this study aimed to investigate the effects of a 12-week in-season ST on measures of physical fitness and injury occurrence in young elite female soccer players. METHODS: Thirty elite female soccer players (15.4 ± 1.9 years; maturity offset + 2.3 ± 1.1 years) participated in this study, and were randomly assigned to a strength training group (STG, n = 14) or an active control (CG, n = 16) group. ST lasted twelve weeks and included full body muscle strengthening exercises using primarily weight machines at progressive intensities ranging between 40 and 85% of the one-repetition-maximum (1-RM). The CG practiced a traditional soccer training program. Overall, training volumes of the two groups were similar with a training load (rating of perceived exertion × time) of 1158.4 ± 67.7 arbitrary unity (AU) for the STG and 1188.8 ± 44.1 AU for the CG. Pre and post training, the following physical fitness tests were applied: dynamic muscle strength (relative [to body mass] and absolute 1-RM bench/leg press, lat-pull down), jump performance (countermovement jump [CMJ], squat jump [SJ], five-jump-test [5JT]), linear-sprint speed (5-m, 10-m, 30-m), change-of-direction speed (T-test with and without ball), sport-specific performance (Yo-Yo Intermittent Level1 [YYIRTL1], and repeated shuttle sprint ability [RSSA]). The injury rate per 1000-h exposure was monitored throughout the soccer season. RESULTS: No significant baseline differences were observed between groups. Statistically significant group-by-time interactions were found for absolute (p < 0.001, d = 2.59) and relative 1-RM bench press (p < 0.001, d = 2.39), absolute 1-RM lat-pull down (p < 0.001, d = 1.68), and relative 1-RM leg press (p < 0.001, d = 1.72). Significant group-by-time interactions were observed for CMJ (p = 0.005, d = 1.27), RSSAmean (p = 0.007, d = 0.81), and RSSAtotal (p < 0.001, d = 1.90). Post-hoc tests indicated that the STG group demonstrated greater improvements in all tested variables compared to CG (1.2 < d < 2.5). However, no significant interaction effects were noted for measures of linear sprint speed and YYIRTL1 performance. Additionally, non-contact injuries during the season were significantly lower (p = 0.003, d = 1.31) in the STG (0.48/1000 h of exposure) than the CG (2.62/1000 h of exposure). CONCLUSIONS: Twelve weeks of an in-season ST resulted in larger physical fitness improvements and fewer injuries compared with an active control in elite young female soccer players. Accordingly, ST should be systematically applied in female soccer to enhance performance and prevent injuries.

Female Athlete Sport Science Versus Applied Practice: Bridging the Gap.

BACKGROUND: Female-specific science, medicine, and innovation have grown steadily since the turn of the decade as the focus on female sport continues to advance. While this growth is welcome, and despite the best of intentions, it is not always coupled with valuable application. PURPOSE: This commentary discusses barriers faced when developing and applying sport-science research and innovation activities in female sport. We offer several practical solutions to help safeguard the progress of female athlete health and performance support. We make 3 suggestions: (1) multicenter studies to increase the number of elite athletes participating in research and enhance statistical power, which is often lacking in sport-science research; (2) further acceptance of case studies in elite sport research, as they can include context alongside athlete data that more traditional research designs perhaps do not; and (3) collaborative, codesigned approaches to research and innovation, wherein researchers, practitioners, and athletes all contribute to balancing scientific rigor with applied "real-world" understanding, which may result in the generation of richer, more meaningful knowledge for the benefit of female athletes and their environments.

Unveiling the Effects of Interval Resistance Training and Chlorella Vulgaris Supplementation on Meteorin-like Protein and Oxidative Stress in Obese Men.

Background: Dysregulation of adipocyte function occurs in obesity. Meteorin-like protein (Metrnl) is a newly discovered modulator of inflammation, metabolism, and differentiation of human adipocytes. The dietary supplement Chlorella Vulgaris (CV) reduces hyperlipidemia, hyperglycemia, and oxidative stress in clinical trials. Objectives: To explore the impact of 12 wks of interval resistance training (IRT) and CV supplementation on plasma levels of Metrnl and oxidative stress in males with obesity. Methods: Forty-four obese men (BMI: 32.0 ± 1.5 kg/m2, weight: 101.1 ± 2.2 kg, age: 23-35 years) were randomly assigned into 4 groups (n = 11/group): control (CON), CV supplement (CV), IRT, and CV + IRT (CVIRT). The IRT was performed for 12 wks (3 sessions per week). The treatment consisted of a daily intake of CV (1800 mg capsule) or placebo capsules. Blood samples were collected 48 hours before and after the interventions to analyze biomedical measurements. Results: The IRT and CVIRT groups had elevations in plasma Metrnl, superoxide dismutase, and total antioxidant capacity levels (all P < 0.0001), and reductions in malondialdehyde (P < 0.0001). Supplementation with CV significantly reduced malondialdehyde (P < 0.001) and increased total antioxidant capacity (P < 0.0001) but failed to alter superoxide dismutase or Metrnl (P > 0.05). Conclusions: Although IRT and its combination with CV hold promise for improving Metrnl levels and oxidative status in obesity, combining IRT and CV do not yield greater benefits than IRT alone. Although standalone CV supplementation could favorably impact certain markers of oxidative stress, the effectiveness of CV supplementation appears to have a relatively limited effect across assessed biomarkers and requires further investigation.

Resting Energy Expenditure, Metabolic and Sex Hormones in Two Phases of the Menstrual and Hormonal Contraceptive Cycles.

INTRODUCTION: Resting energy expenditure (REE) may fluctuate during the menstrual cycle (MC), due to the physiological effects of estradiol (E2) and progesterone (P4). This study examined changes in REE and metabolic hormones (leptin, ghrelin, thyroid hormones), and dietary intake in two hormonally distinct groups, naturally menstruating women (NoOC) and women using monophasic combined oral contraceptives (COC). METHODS: Measurements included REE by indirect calorimetry, body composition by bioimpedance, and blood samples for hormone analysis in the early follicular and mid-luteal phases of the MC in NoOC-group (n = 38) or the active and inactive phases of the COC cycle (COC, n = 19). Participants recorded their food intake for 3 days after measurements. A secondary analysis was completed for the NoOC-group without REE outliers (difference between measurements >1.5 × interquartile range, n = 4). RESULTS: In the NoOC-group, luteal phase REE was 40 kcal higher than follicular phase REE [95% confidence interval (CI): -2 kcal/d-82 kcal/d, d = 0.20, p = 0.061]. Leptin (d = 0.35, p < 0.001), T3 (d = 0.26, p = 0.05) and fat intake (d = 0.48, p = 0.027) were lower, and T4 (d = 0.21, p = 0.041) was higher in the luteal phase. After excluding outliers, REE was 44 kcal higher in the luteal phase than in the follicular phase (95% CI: 12 kcal/d-76 kcal/d, d = 0.22, p = 0.007). In the COC-group, the mean difference in REE was -2 kcal (95% CI-82 kcal/d-79 kcal/d) between active and inactive phases, while T3 was higher in the inactive phase (d = 0.01, p = 0.037). CONCLUSIONS: REE increases only slightly from the follicular to the luteal phase but remains unchanged between COC phases. Increases in T3, leptin, and fat intake during the luteal phase might echo metabolic fluctuations that parallel female sex hormones during the MC.

Effects of Hormonal Contraception and the Menstrual Cycle on Maximal Strength and Power Performance.

INTRODUCTION: To evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared to an eumenorrheic (EUM) cycle, on maximal strength and power between hormone phases. METHODS: One repetition max (1RM) leg press and bench press, peak force (PF) from knee extension and upright row isometric dynamometry, and power from vertical jump height (VJH) and reactive strength index (RSI; cm/s) were measured in 60 healthy, active women (mean ± standard deviation [SD]; Age: 26.5 ± 7.0 yrs, BMI: 22.5 ± 3.7 kg/m2) who were monophasic OC users for ≥6 months (n = 21), had a H-IUD for ≥6 months (n = 20), or had regularly naturally occurring menstrual cycle for ≥3 months or were using a non-hormonal IUD (EUM; n = 19). Participants were randomly assigned to begin in the follicular phase/placebo pill (low hormone phase; LHP) or in the luteal phase/active pill (high hormone phase; HHP) and were tested once in each phase. Estimates of total lean mass (LM), leg LM, and arm LM were measured via dual energy x-ray absorptiometry. Separate univariate ANCOVAs were used to assess the change from HHP to LHP between groups, with LM and progesterone as covariates. RESULTS: Leg press 1RM was significantly different across phases between groups (p = 0.027), with higher leg press 1RM in the HHP for the OC group (mean difference[∆HHP-LHP] ± standard error: ∆7.4 ± 15.9 kg; p = 0.043) compared to the H-IUD group (∆-8.9 ± 23.8 kg; p = 0.043). All groups demonstrated similar bench press 1RM, PF, VJH, and RSI between phases (p > 0.05). CONCLUSIONS: Lower body strength was greater in the HHP for OC users (5.6% increase) suggesting lower body maximal strength outcomes may be influenced by hormonal contraception type.

Androgenic Steroid Hormones and Endurance Exercise in Athletic Women.

This study investigated the impact of intensive endurance exercise on circulating androgenic steroid hormones in women. Fifteen normally menstruating athletic women participated. They completed intensive endurance exercise (treadmill running) until volitional fatigue in their follicular phase, with blood samples collected at pre-exercise, volitional fatigue, 90 min and 24 h into recovery. The steroid hormones (total, free testosterone, dehydroepiandrosterone [DHEA], and DHEA-sulfate [DHEA-S], cortisol) were analyzed in blood sera. Non-parametric statistics were used to assess changes across exercise and recovery. At volitional fatigue, all hormones, except free testosterone, were significantly (p < 0.05) increased compared to pre-exercise levels. Most hormones remained elevated through 90 min of recovery, with DHEA, DHEA-S, and total testosterone changes being significant (p < 0.05). At 24 h of recovery, hormonal levels were reduced; specifically, DHEA, DHEA-S, and total testosterone compared to baseline (p < 0.01 to 0.06). Increases in cortisol levels at volitional fatigue and 90 min of recovery were correlated with reductions in total testosterone, DHEA, and DHEA-S observed at 24 h of recovery (rho > -0.62, p < 0.05). In conclusion, in menstruating women performing intensive endurance exercise during their follicular phase, their androgenic steroid hormones remain elevated during early recovery but are suppressed at 24 h of recovery. The latter finding indicates that establishing a resting endocrine equilibrium requires a longer recovery period than 24 h.

Beyond Menstrual Dysfunction: Does Altered Endocrine Function Caused by Problematic Low Energy Availability Impair Health and Sports Performance in Female Athletes?

Low energy availability, particularly when problematic (i.e., prolonged and/or severe), has numerous negative consequences for health and sports performance as characterized in relative energy deficiency in sport. These consequences may be driven by disturbances in endocrine function, although scientific evidence clearly linking endocrine dysfunction to decreased sports performance and blunted or diminished training adaptations is limited. We describe how low energy availability-induced changes in sex hormones manifest as menstrual dysfunction and accompanying hormonal dysfunction in other endocrine axes that lead to adverse health outcomes, including negative bone health, impaired metabolic activity, undesired outcomes for body composition, altered immune response, problematic cardiovascular outcomes, iron deficiency, as well as impaired endurance performance and force production, all of which ultimately may influence athlete health and performance. Where identifiable menstrual dysfunction indicates hypothalamic-pituitary-ovarian axis dysfunction, concomitant disturbances in other hormonal axes and their impact on the athlete's health and sports performance must be recognized as well. Given that the margin between podium positions and "losing" in competitive sports can be very small, several important questions regarding low energy availability, endocrinology, and the mechanisms behind impaired training adaptations and sports performance have yet to be explored.

Exercise and Neuroendocrinology.

The intent of this chapter is to provide a basic overview and explanation of the neuroendocrine system responses to an exercise session in healthy adults. Specifically, the physiologic mechanisms for inducing the hormonal responses of this system and the scope of such responses are addressed. Additionally, factors that augment or attenuate exercise hormonal responses are presented as well as issues related to sex differences, and exercise-related hormonal dysfunction.

Adipokine modulation in obesity: Evaluating the integrative impact of chlorella vulgaris supplementation and interval resistance training in obese males.

Aims: To evaluate the effects of 12-week chlorella vulgaris (CV) combined with interval resistance training (IRT) on plasma levels of leptin, adiponectin and neuregulin-4 (Nrg-4) in obese men. Methods: Obese men (n = 44, BMI of 32.1 ± 1.5 kg/m2) were randomly allocated to the following groups of 11 participants per group: Control Placebo group (CP), CV supplement group (CV), Interval Resistance Training group plus Placebo (IRT + P), and Interval Resistance Training plus CV supplement group (IRT + CV). IRT was performed three times a week for 12 weeks using three sets of 10 repetitions at 60 % 1RM, and integrating an active rest interval with 15 repetitions at 20 % 1RM. Participants consumed either CV (1800 mg daily) or a placebo. Pre- and post-intervention blood samples were obtained to assess adipokines which were measured by ELISA. Results: While CV or IRT separately did not alter plasma levels of leptin (p > 0.05), their combination reduced leptin levels (p = 0.007). IRT and IRT plus CV increased the plasma levels of adiponectin and Nrg-4 (p < 0.01). An intergroup comparison indicated significant elevations of adiponectin and Nrg-4 in the CV compared to the CP group (p < 0.05). Conclusion: The combination of IRT and CV modulates plasma levels of leptin, adiponectin and NRG4 more effectively than either IRT or CV separately in obese men.

A reproducible, self-reported, field-based tool for monitoring ovarian hormone status and body weight variations in female athletes: the Answ'Her questionnaire.

BACKGROUND: Intra-individual factors like ovarian hormone profiles and body weight variations may influence sports practice and performance in female athletes and need to be characterized. The "Answ'Her" questionnaire was designed to develop a relevant and reproducible field-based tool to assess self-reported ovarian hormone status (natural menstrual cycle and hormonal contraceptive use) and body weight variations practices among female athletes. METHODS: French females with a regular sports practice responded (once: N.=210; twice: N.=86; thrice: N.=66) to this 73-item questionnaire reporting their ovarian hormone status, associated symptoms, perceived influence on sports practice, and body weight variations. Reproducibility was evaluated, then a descriptive cross-sectional analysis was conducted on athletes. RESULTS: Reproducibility was verified with 92% of Lin's correlation concordance coefficients above 0.7 and 100% of weighted agreements above 70%. Ultimately 185 female athletes (23.0±4.8 years) were included in the cross-sectional analysis. Whether they used hormonal contraceptive (46.5%) or not (53.5%), most of the athletes perceived a negative impact of their ovarian hormone status on sports practice (78.7%) and performance (84.7%). Overall, 77.3% of the athletes had experienced body weight variations that were significantly associated with an interruption of menses (>3 months) and menses irregularity over the last three years. CONCLUSIONS: The Answ'Her questionnaire is a simple and effective reproducible field-based tool for the self-reported characterisation of female athlete ovarian hormone status and body weight variations. It could be used for a unique and simple overview of the athlete situation but also in a longitudinal design to assess the athlete's evolution and/or effectiveness of implanted training strategies.

Effects of a Preseason Neuromuscular Training Program vs. an Endurance-Dominated Program on Physical Fitness and Injury Prevention in Female Soccer Players.

BACKGROUND: The pre-season preparatory period is considered key for optimizing the physical fitness levels needed to withstand congested match periods and preventing injuries during the regular soccer season. This study contrasted the effects s of neuromuscular training (NMT) versus an endurance-dominated training (ET) program conducted during the preseason on measures of physical fitness and injury occurrence in female soccer players. METHODS: Twenty-four female soccer players aged 17.0 ± 1.3 years from a professional soccer club participated in this study. Players were randomly assigned to NMT (n = 12) or ET (n = 12) groups according to their playing position. The preseason intervention program lasted six weeks, with three weekly sessions with a duration of 45-60 min per session. Exercises in the NMT group included muscle strengthening exercises, plyometrics, agility and dynamic stability exercises, while the ET group practiced a traditional pre-season training program consisting of running and sprinting exercises, fartlek, and high-intensity interval training. The training volumes were similar in the two study groups. Anthropometric measurements, physical fitness tests (i.e., linear and change-of-direction speed, muscle strength and power tests) and the overall injury rate per 1000 h of exposure (training, match) were recorded throughout the season. RESULTS: No between group differences were found at pre (T1). Significant group-by-time interactions were observed for the 5, 10, and 30-m linear sprint speed tests (p < 0.001, 2.16 < d < 2.58), the T-test (p = 0.024, d = 1.03), the squat (p < 0.001, d = 4.04), and the countermovement jump test (p < 0.001, d = 2.21), the Loughborough soccer passing test (LSPT) (p = 0.019, d = 1.08), and the 1-RM back squat test (p < 0.001, d = 2.53). Post-hoc tests indicated that NMT provided larger improvements for SJ, CMJ, 1-RM back squat, the 5-m sprint, 10-m sprint, 30-m sprint, T-test and LSPT compared to ET (1.07 > d > 2.77). The injury rate across the season was significantly lower in the NMT (5.1/1000 h exposure) compared to ET (11.8/1000 h exposure) (p = 0.014). CONCLUSIONS: The findings support that six-weeks of preseason NMT versus ET induced larger performance improvements, and significantly reduced injury occurrence in elite female soccer players.

Effects of HIIT training and HIIT combined with circuit resistance training on measures of physical fitness, miRNA expression, and metabolic risk factors in overweight/obese middle-aged women.

OBJECTIVE: The purpose of this study was to examine the effects of 10 weeks of high-intensity interval training (HIIT) and HIIT combined with circuit resistance training (HCRT) on selected measures of physical fitness, the expression of miR-9, -15a, -34a, -145, and - 155 as well as metabolic risk factors including lipid profiles and insulin resistance in middle-aged overweight/obese women. METHODS: Twenty-seven overweight/obese women aged 35-50 yrs. were randomized to HIIT (n = 14) or HCRT (n = 13) groups. The HIIT group performed running exercises (5 reps x 4 min per session) with active recovery between repetitions for 10 weeks with 5 weekly sessions. The HCRT group performed 10 weeks of HIIT and resistance training with 3 weekly HIIT sessions and 2 weekly HCRT sessions. Anthropometric measures (e.g., body mass), selected components of physical fitness (cardiovascular fitness, muscle strength), levels of miRNAs (miR-9, -15a, -34a, -145, and - 155), lipid profiles (total cholesterol; TC, Triglycerides; TG, low-density lipoprotein cholesterol; LDL-C and high-density lipoprotein cholesterol; HDL-C), and insulin resistance; HOMA-IR index, were measured at baseline and week 10. RESULTS: An ANOVA analysis indicated no significant group by time interactions (p > 0.05) for all anthropometric measures, and maximum oxygen consumption (VO2max). A significant group by time interaction, however, was found for the one-repetition maximum (IRM; p < 0.001, ES= 0.751 , moderate). A post-hoc test indicated an increase in the pre-to-post mean 1RM for HCRT (p = 0.001, ES = 1.83, large). There was a significant group by time interaction for miR-155 (p = 0.05, ES = 0.014, trivial). Levels for miR-155 underwent pre-to-post HIIT increases (p = 0.045, ES = 1.232, large). Moreover, there were also significant group by time interactions for TC (p = 0.035, ES = 0.187, trivial), TG (p < 0.001, ES = 0.586, small), LDL-C (p = 0.029, ES = 0.200, small) and HDL-C (p = 0.009, ES = 0.273, small). Post-hoc tests indicated pre-post HCRT decreases for TC (p = 0.001, ES = 1.44, large) and HDL-C (p = 0.001, ES = 1.407, large). HIIT caused pre-to-post decreases in TG (p = 0.001, ES = 0.599, small), and LDL-C (p = 0.001, ES = 0.926, moderate). CONCLUSIONS: Both training regimes did not improve cardiovascular fitness. But, HCRT improved lower/upper limb muscle strength, and HIIT resulted in an increase in miR-155 expression in peripheral blood mononuclear cells. Furthermore, HIIT and HCRT each improved selected metabolic risk factors including lipid profiles and glucose and insulin metabolism in overweight/obese middle-aged women. TRIAL REGISTRATION: OSF, October, 4th 2023. Registration DOI: https://doi.org/10.17605/OSF.IO/UZ92E . osf.io/tc5ky . "Retrospectively registered".

Effects of Hormonal Contraception and the Menstrual Cycle on Fatigability and Recovery From an Anaerobic Exercise Test.

ABSTRACT: Cabre, HE, Ladan, AN, Moore, SR, Joniak, KE, Blue, MNM, Pietrosimone, BG, Hackney, AC, and Smith-Ryan, AE. Effects of hormonal contraception and the menstrual cycle on fatigability and recovery from an anaerobic exercise test. J Strength Cond Res 38(7): 1256-1265, 2024-This study sought to evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with a eumenorrheic (EUM) cycle, on fatigability and recovery between hormone the phases. Peak power (PP), average power (AP), fatigue index (FI), blood lactate, vessel diameter, and blood flow (BF) were measured from a repeated sprint cycle test (10 × 6 seconds) in 60, healthy, active women (mean ± SD ; age: 26.5 ± 7.0 years, BMI: 22.5 ± 3.7 kg·m -2 ) who used monophasic OC (≥6 months; n = 21), had a H-IUD (≥6 months; n = 20), or had regular naturally occurring menstrual cycle (≥3 months) or had a nonhormonal IUD (EUM; n = 19). Subjects were randomly assigned to begin in either the low-hormone phase (LHP) or high-hormone phase (HHP) and were tested once in each phase. Separate univariate analyses of covariances assessed the change from HHP to LHP between the groups, covaried for progesterone, with significance set at p ≤ 0.05. All groups demonstrated similar changes in PP, AP, FI, blood lactate, vessel diameter, and BF between the phases ( p > 0.05). Although not significant, AP was higher in LHP for OC (Δ -248.2 ± 1,301.4 W) and EUM (Δ -19.5 ± 977.7 W) and higher in HHP for H-IUD (Δ 369.3 ± 1,123.0 W). Oral contraceptive group exhibited a higher FI (Δ 2.0%) and reduced blood lactate clearance (Δ 2.5%) in HHP. In recreationally active women, hormonal contraception and hormone phases may minimally impact fatigue and recovery. Individual elite female athletes may benefit from understanding hormonal contraception type as performance and recovery may slightly vary across the cycle.

A Systematic Review and Meta-analysis of the Association Between ACTN3 R577X Genotypes and Performance in Endurance Versus Power Athletes and Non-athletes.

BACKGROUND: Previous studies reported differences in genotype frequency of the ACTN3 R577X polymorphisms (rs1815739; RR, RX and XX) in athletes and non-athletic populations. This systematic review with meta-analysis assessed ACTN3 R577X genotype frequencies in power versus endurance athletes and non-athletes. METHODS: Five electronic databases (PubMed, Web of Science, Scopus, Science Direct, SPORTDiscus) were searched for research articles published until December 31st, 2022. Studies were included if they reported the frequency of the ACTN3 R577X genotypes in power athletes (e.g., weightlifters) and if they included a comparison with endurance athletes (e.g., long-distance runners) or non-athletic controls. A meta-analysis was then performed using either fixed or random-effects models. Pooled odds ratios (OR) were determined. Heterogeneity was detected using I2 and Cochran's Q tests. Publication bias and sensitivity analysis tests were computed. RESULTS: After screening 476 initial registrations, 25 studies were included in the final analysis (13 different countries; 14,541 participants). In power athletes, the RX genotype was predominant over the two other genotypes: RR versus RX (OR 0.70; 95% CI 0.57-0.85, p = 0.0005), RR versus XX (OR 4.26; 95% CI 3.19-5.69, p < 0.00001), RX versus XX (OR 6.58; 95% CI 5.66-7.67, p < 0.00001). The R allele was higher than the X allele (OR 2.87; 95% CI 2.35-3.50, p < 0.00001) in power athletes. Additionally, the frequency of the RR genotype was higher in power athletes than in non-athletes (OR 1.48; 95% CI 1.25-1.75, p < 0.00001). The RX genotype was similar in both groups (OR 0.84; 95% CI 0.71-1.00, p = 0.06). The XX genotype was lower in power athletes than in controls (OR 0.73; 95% CI 0.64-0.84, p < 0.00001). Furthermore, the R allele frequency was higher in power athletes than in controls (OR 1.28; 95% CI 1.19-1.38, p < 0.00001). Conversely, a higher frequency of X allele was observed in the control group compared to power athletes (OR 0.78; 95% CI 0.73-0.84, p < 0.00001). On the other hand, the frequency of the RR genotype was higher in power athletes than in endurance athletes (OR 1.27; 95% CI 1.09-1.49, p = 0.003). The frequency of the RX genotype was similar in both groups (OR 1.07; 95% CI 0.93-1.24, p = 0.36). In contrast, the frequency of the XX genotype was lower in power athletes than in endurance athletes (OR 0.63; 95% CI 0.52-0.76, p < 0.00001). In addition, the R allele was higher in power athletes than in endurance athletes (OR 1.32; 95% CI 1.11-1.57, p = 0.002). However, the X allele was higher in endurance athletes compared to power athletes (OR 0.76; 95% CI 0.64-0.90, p = 0.002). Finally, the genotypic and allelic frequency of ACTN3 genes were similar in male and female power athletes. CONCLUSIONS: The pattern of the frequencies of the ACTN3 R577X genotypes in power athletes was RX > RR > XX. However, the RR genotype and R allele were overrepresented in power athletes compared to non-athletes and endurance athletes. These data suggest that the RR genotype and R allele, which is associated with a normal expression of α-actinin-3 in fast-twitch muscle fibers, may offer some benefit in improving performance development in muscle strength and power.

Effect of Menstrual Cycle Phase on Perceived Exertion During Aerobic Exercise in Eumenorrheic Women: A Systematic Review and Meta-analysis.

Background: The rating of perceived exertion (RPE) is a readily available and practical tool widely used in exercise science to monitor exercise load, but a rigorous review of the effect of menstrual cycle (MC) phases on RPE within continuous aerobic exercise has not yet been completed. Objective: This study investigated the effects of the MC phase on RPE during aerobic exercise. Study Design: This was a systematic review and meta-analysis. Methods: The search strategy was carried out using the 5 most common scientific databases. While qualitative analyses were performed in all included studies, random effects to standard mean difference were calculated and meta-analysis was performed where possible. This study addresses comparison for RPE at the beginning, middle, and end of the exercise adopting 2 mains analysis. The first adopted early cycle (first session of the cycle) as control compared with the subsequent phases, and the second adopted days 1 to 5 (early follicular) as control compared with the subsequent phases. Results: A total of 17 studies (n = 160) were included in the qualitative synthesis. The meta-analysis showed that MC phases did not impact RPE (P > .05). Conclusions: The current meta-analysis showed that MC does not impact RPE. Although acute RPE is not impacted by MC phases, future studies and practitioners should pay attention to the impact of RPE session by session throughout the MC.

Female Physiology-Endocrinology: Education Is Lacking and Innovation Is Needed!

Throughout their lifespans, women undergo unique endocrinological changes relative to their reproductive hormones. The influence of how the female sex steroid hormones have nonreproductive actions is a trending topic of great interest in the exercise-sports sciences, especially among women of reproductive age. Herein, we present several key points on our perspective for moving the study of this topic forward in the future. These are (a) encouraging researchers to pursue high-quality research on female physiology-endocrinology in the exercise-sports science setting, (b) the need for exercise-sports science educational curriculums at the university level to embrace the study of female physiology-endocrinology area, and (c) the need for innovation in the study of this topic. As such, we propose using research design models involving supraphysiological hormonal states in vivo, that is, pregnancy and in vitro fertilization treatment, to gain new insights on sex steroid hormonal actions in women. Herein, we provide the rationale for our recommendations as well as a brief physiological overview of these clinical states. We acknowledge, exercise sports sciences need more studies on women! But there is a need to "think outside the box" on this topic, and we encourage researchers to be unconventional, be bold, think creatively, and contemplate whether these supraphysiological hormonal states might give them insightful information on female physiology and ovarian sex steroid hormones actions.

Effects of Passive or Active Recovery Regimes Applied During Long-Term Interval Training on Physical Fitness in Healthy Trained and Untrained Individuals: A Systematic Review.

BACKGROUND: Intermittent exercise programs characterized through intensive exercise bouts alternated with passive or active recovery (i.e., interval training), have been proven to enhance measures of cardiorespiratory fitness. However, it is unresolved which recovery type (active or passive) applied during interval training results in larger performance improvements. OBJECTIVES: This systematic review aimed to summarize recent evidence on the effects of passive or active recovery following long-term interval exercise training on measures of physical fitness and physiological adaptations in healthy trained and untrained individuals. The study protocol was registered in the Open Science Framework (OSF) platform ( https://doi.org/10.17605/OSF.IO/9BUEY ). METHODS: We searched nine databases including the grey literature (Academic Search Elite, CINAHL, ERIC, Open Access Theses and Dissertations, Open Dissertations, PsycINFO, PubMed/MEDLINE, Scopus, and SPORTDiscus) from inception until February 2023. Key terms as high-intensity interval training, recovery mode, passive or active recover were used. A systematic review rather than a meta-analysis was performed, as a large number of outcome parameters would have produced substantial heterogeneity. RESULTS: After screening titles, abstracts, and full texts, 24 studies were eligible for inclusion in our final analysis. Thirteen studies examined the effects of interval training interspersed with passive recovery regimes on physical fitness and physiological responses in trained (6 studies) and untrained (7 studies) individuals. Eleven out of 13 studies reported significant improvements in physical fitness (e.g., maximal aerobic velocity (MAV), Yo-Yo running test, jump performance) and physiological parameters (e.g., maximal oxygen uptake [VO2max], lactate threshold, blood pressure) in trained (effect sizes from single studies: 0.13 < Cohen's d < 3.27, small to very large) and untrained individuals (effect sizes: 0.17 < d < 4.19, small to very large) despite the type of interval training or exercise dosage (frequency, intensity, time, type). Two studies were identified that examined the effects of passive recovery applied during interval training in young female basketball (15.1 ± 1.1 years) and male soccer players (14.2 ± 0.5 years). Both studies showed positive effects of passive recovery on VO2max, countermovement jump performance, and the Yo-Yo running test. Eleven studies examined the effects of interval training interspersed with active recovery methods on physical fitness and physiological parameters in trained (6 studies) and untrained individuals (5 studies). Despite the type of interval training or exercise dosage, nine out of eleven studies reported significant increases in measures of physical fitness (e.g., MAV) and physiological parameters (e.g., VO2max, blood pressures) in trained (effect sizes from single studies: 0.13 < d < 1.29, small to very large) and untrained individuals (effect sizes: 0.19 < d < 3.29, small to very large). There was no study available that examined the effects of active recovery on physical fitness and physiological responses in youth. CONCLUSIONS: The results of this systematic review show that interval training interspersed with active or passive recovery regimes have the potential to improve measures of physical fitness and physiology outcomes in trained and untrained adults and trained youth. That is, the applied recovery type seems not to affect the outcomes. Nonetheless, more research is needed on the effects of recovery type on measures of physical fitness and physiological adaptations in youth.

Influence of energy availability on metabolic hormonal profiles in east African female and male distance runners.

BACKGROUND: Energy availability (EA) and relative energy deficiency in sport (RED-S) are understudied in East African endurance athletes, both females (F) and males (M). This study assessed the metabolic hormonal profiles of such athletes relative to their EA status. METHODS: Forty athletes (F=16, M=24) had their EA status, training, maximal oxygen uptake, and resting blood samples assessed using standard research practices. Subjects were stratified into two groups, high EA (HiEA) and low EA (LoEA) based on combined median value. RESULTS: Cortisol (P=0.034) and insulin (P=0.044) were significantly elevated in the LoEA group, while growth hormone (P=0.045) was significantly suppressed; and, prolactin (P=0.078) trended towards suppression, respectively compared to the HiEA group. All other hormonal comparison were non-significant. CONCLUSIONS: Metabolic hormonal profiles of female and male African distance runners are affected by their EA status. Aspects of these alterations agree in part with published findings based upon White populations, although some differences exist and need further investigation.

Physical Activity Associates with T1rho MRI of Femoral Cartilage After Anterior Cruciate Ligament Reconstruction.

PURPOSE: Less physical activity has been associated with systemic biomarkers of cartilage breakdown after anterior cruciate ligament reconstruction (ACLR). However, previous research lacks analysis of deleterious cartilage compositional changes and objective physical activity after ACLR. The purpose of this study was to determine the association between physical activity quantified via accelerometer-based measures of daily steps and time in moderate-to-vigorous physical activity (MVPA), and T1rho magnetic resonance imaging (MRI) of the femoral articular cartilage, a marker of proteoglycan density in individuals with ACLR. METHODS: Daily steps and MVPA were assessed over 7 d using an accelerometer worn on the hip in 26 individuals between 6 and 12 months after primary unilateral ACLR. Resting T1rho MRI was collected bilaterally, and T1rho MRI interlimb ratios (ILR: ACLR limb/contralateral limb) were calculated for lateral and medial femoral condyle regions of interest. We conducted univariate linear regression analyses to determine associations between T1rho MRI ILRs and daily steps and MVPA with and without controlling for sex. RESULTS: Greater T1rho MRI ILR of the central lateral femoral condyle, indicative of less proteoglycan density in the ACLR limb, was associated with greater time in MVPA ( R2 = 0.178, P = 0.032). Sex-adjusted models showed significant interaction terms between daily steps and sex in the anterior ( P = 0.025), central ( P = 0.002), and posterior ( P = 0.002) medial femoral condyle. CONCLUSIONS: Lesser physical activity may be a risk factor for maintaining cartilage health after ACLR; additionally, the relationship between physical activity and cartilage health may be different between males and females.

Effects of the Type of Exercise Training on Bone Health Parameters in Adolescent Girls: A Systematic Review.

Interventional studies offer strong evidence for exercise's osteogenic impact on bone particularly during growth. With rising osteoporosis rates in older women, enhancing bone strength early in life is crucial. Thus, investigating the osteogenic effects of different types of physical activities in young females is crucial. Despite varied findings, only two systematic reviews tried to explore this topic without examining how different types of exercise may affect bone health in adolescent girls. The first aim of this systematic review was to assess the impact of exercise training on bone health parameters in adolescent girls, and the second aim was to investigate whether the type of exercise training can modulate this effect. A systematic literature search was conducted using common electronic databases from inception - January 2023. Seven studies (355 participants) were eligible for inclusion in this systematic review. Two studies dealt with resistance training, 3 studies applied plyometric training, 1 study used team sports, and 1 study used dancing. Results indicate that plyometric training increases lumbar spine bone mass in adolescent girls. Well-designed randomized controlled trials with a proper training period (> 12 weeks) are needed to advocate a specific type of training which has the highest osteogenic effect.