The influence of estrogen on skeletal muscle: sex matters

Effects of Eccentric Exercise of the Extensors on Eccentric Exercise-Induced Muscle Damage of the Flexors in Limbs

INTRODUCTION

We tested the hypothesis that muscle damage protection effect would be induced by its antagonist muscle eccentric exercise.

METHODS

Sedentary young (20-28 yr) men were randomly assigned into six groups; three groups each for arm or leg exercise group ( n = 12/group). One group performed two bouts of 30 maximal eccentric contractions (30MaxEC) of the elbow flexors (EF) or 60 maximal eccentric contractions (60MaxEC) of the knee flexors (KF) using a different arm (contra-EF-EF) or leg (contra-KF-KF) between bouts. The other two groups performed 30MaxEC of the elbow extensors (EE) or 60MaxEC of the knee extensors (KE) first followed by the 30MaxEC of EF or 60MaxEC of KF using the ipsilateral (ipsi-EE-EF, ipsi-KE-KF) or contralateral limb (contra-EE-EF, contra-KE-KF). The two exercise bouts were separated by 2 wk for all groups. Changes in muscle damage markers before to 5 d after exercise were compared among the groups by mixed-design two-way ANOVA.

RESULTS

Changes in the markers after the second bout of the ipsi-EE-EF, contra-EE-EF, ipsi-KE-KF, and contra-KE-KF groups were smaller ( P < 0.05) than those after the first bout of the contra-EF-EF and contra-KF-KF groups, respectively. The changes after the second bout were smaller ( P < 0.05) for the ipsi-EE-EF than contra-EE-EF, and ipsi-KE-KF than contra-KE-KF group; however, those in the contra-EE-EF and contra-KE-KF groups were larger ( P < 0.05) than those after the second bout of the contra-EF-EF and contra-KF-KF groups.

CONCLUSIONS

These results showed that the magnitude of muscle damage of EF or KF was reduced by the initial bout of EE or KE eccentric exercise performed by both ipsilateral and contralateral limbs, suggesting that muscle damage protective effect is conferred by the antagonist muscle in the same and opposite limbs.

Utilization of CoRDS registry to monitor quality of life in patients with VCP multisystem proteinopathy

BACKGROUND

VCP disease, also known as multisystem proteinopathy, is a rare, autosomal dominant, adult-onset, neuromuscular disease that is caused by variants in the valosin-containing protein (VCP) gene. VCP disease may exhibit one or more of the following primary features: inclusion body myopathy, Paget's disease of bone (PDB), Frontotemporal dementia, and amyotrophic lateral sclerosis. Due to its progressive nature, death normally occurs in their sixties due to respiratory and cardiac failure. The purpose of this study is to utilize the Cure VCP Disease patient registry hosted by the Coordination of Rare Diseases at Sanford (CoRDS) to conduct a prospective natural history study.

METHODS

Seventy-nine participants enrolled in the patient registry and answered demographic, VCP variant type, Patient-reported outcome measures (PROMs), and quality of life (QOL) questionnaires over the course of 3 years. We additionally investigated if any sex differences existed and if genotype-phenotype correlations affected the rate of progression of the varying clinical manifestations.

RESULTS

Overall, participants' mobility declined significantly as the disease progressed. Participants reported a 0.6% decline in upper extremity function, 1.2% decline in lower extremity function, and 0.3% decline in cognitive function per year of age. Furthermore, participants reported a 1.6% decline in upper and lower extremity function and a 0.1% decline in cognitive function per year of disease duration. The highest PROMs correlations were noted between overall health and lower extremity function, upper extremity function, fatigue, and the ability to perform vigorous activities. Genotype-phenotype correlations revealed no significant differences except for the absence of PDB in the p.Arg159Cys group.

CONCLUSION

The VCP CoRDS Registry was found to be a valuable tool for monitoring the QOL in patients with VCP disease and capturing patient perspectives for future clinical trials.

Sex differences in absolute and relative changes in muscle size following resistance training in healthy adults: a systematic review with Bayesian meta-analysis

Background

Muscle hypertrophy may be influenced by biological differences between males and females. This meta-analysis investigated absolute and relative changes in muscle size following resistance training (RT) between males and females and whether measures of muscle size, body region assessed, muscle fibre type, and RT experience moderate the results.

Methods

Studies were included if male and female participants were healthy (18-45 years old) adults that completed the same RT intervention, and a measure of pre- to post-intervention changes in muscle size was included. Out of 2,720 screened studies, 29 studies were included in the statistical analysis. Bayesian methods were used to estimate a standardised mean difference (SMD), log response ratio (lnRR) with exponentiated percentage change (Exp. % Change of lnRR), and probability of direction (pd) for each outcome.

Results

Absolute increases in muscle size slightly favoured males compared to females (SMD = 0.19 (95% HDI: 0.11 to 0.28); pd = 100%), however, relative increases in muscle size were similar between sexes (Exp. % Change of lnRR = 0.69% (95% HDI: -1.50% to 2.88%)). Outcomes were minimally influenced by the measure of muscle size and not influenced by RT experience of participants. Absolute hypertrophy of upper-body but not lower-body regions was favoured in males. Type I muscle fibre hypertrophy slightly favoured males, but Type II muscle fibre hypertrophy was similar between sexes.

Conclusion

Our findings strengthen the understanding that females have a similar potential to induce muscle hypertrophy as males (particularly when considering relative increases in muscle size from baseline) and findings of our secondary analyses should inform future research that investigates sex differences in highly trained participants and muscle fibre type-specific hypertrophy.

Temporal trends in the burden of musculoskeletal diseases in China from 1990 to 2021 and predictions for 2021 to 2030

BACKGROUND

Musculoskeletal (MSK) diseases represent a significant global public health challenge. Conducting comprehensive research on MSK diseases in China holds profound implications for public health.

METHODS

This study utilized data from the Global Burden of Disease 2021 (GBD 2021) to analyze the incidence rate, prevalence rate, mortality rate, disability-adjusted life years (DALYs), years lived with disability (YLDs), and years of life lost (YLLs) of MSK diseases in China from 1990 to 2021. Trends were evaluated using annual percentage change (APC), average annual percentage change (AAPC), and estimated annual percentage change (EAPC). Future disease trends were predicted using the Bayesian Age-Period-Cohort (BAPC) model.

RESULTS

China had the highest number of DALYs cases globally, totaling 30.4194 million. Low back pain (LBP) represented the largest burden, while hand osteoarthritis exhibited the fastest growth. Differences in disease burden were observed across various genders and age groups. Predictions indicate that between 2021 and 2030, the age-standardized DALYs rate in China will increase annually, reaching 1779.08 per 100,000 population by 2030. Environmental (occupational) factors had the most significant impact on the age-standardized DALYs rate, whereas renal dysfunction had the least impact. The SDI showed a moderately strong positive correlation with the age-standardized DALYs rate of MSK diseases.

CONCLUSION

Over the past 20 years, the prevalence of MSK diseases in China has experienced a slight increase, while other epidemiological burden indicators have shown a downward trend. Projections indicate that the overall disease burden of MSK in China will continue to rise over the next decade, underscoring the need for early intervention strategies. Moreover, substantial differences in MSK disease burden across genders and age groups highlight the importance of developing targeted policy interventions to mitigate this burden.

An exploratory study of serum creatine kinase as a prognostic marker for patients with resectable pancreatic cancer: looking into the relationship with body composition

BACKGROUND

Among cancer patients, pancreatic cancer patients have the highest rate of sarcopenia, which is a critical prognostic factor. Serum creatine kinase (CK) is closely related to skeletal muscle mass and has been reported to decline with the progression of cancer. This study investigated whether preoperative serum CK is associated with the survival of patients with pancreatic cancer.

METHODS

Data were obtained from patients with pathologically confirmed pancreatic cancer between June 2016 and March 2022. The prognostic significance of CK was analyzed based on sex-stratified groups. The Kaplan-Meier method was used to compare overall survival (OS) and disease-free survival (DFS). Multivariate Cox proportional hazards models were used to determine prognostic factors. Body composition was analyzed based on preoperative abdominal CT images to explore the sex-specific associations between skeletal muscle area (SMA) and serum CK levels.

RESULTS

A total of 166 patients were included in this study. Sarcopenia was presented in 70 patients (42.2%). A low serum CK level showed a significant correlation with the diagnosis of sarcopenia in male patients (P = 0.026). The levels of CK did not predict the outcome in female patients, while a low preoperative CK was notably linked to shorter OS in male patients (median OS: 15 months vs. 33 months, P = 0.011; median DFS: 5 months vs. 14 months, P = 0.007). Multivariate analyses further confirmed the effect of CK in predicting OS (CK>44 IU/L, HR:0.226, 95% CI:0.107-0.478, P < 0.001) and DFS (CK>44 IU/L, HR:0.272, 95% CI:0.139-0.529, P < 0.001) of male patients. Correlation analysis revealed a significant association between SMA and CK levels in male patients (r = 0.225, P = 0.025), and such a correlation was not observed in female patients (r = 0.088, P = 0.478).

CONCLUSION

The pretherapeutic CK may represent a simple marker for predicting poor survival in male patients with resectable pancreatic cancer, thereby aiding in the selection of therapeutic strategies.

Where Are All the Female Participants in Sports and Exercise Medicine Research? A Decade Later

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.

Impact of structural factors around the accessory nerve on the pathogenesis of essential neck and upper-back stiffness: a sonographic investigation

INTRODUCTION

Neck and upper-back stiffness involves discomfort/ache in the trapezius muscle (TM). The pathogenesis of 'essential neck and upper-back stiffness' without obvious causes remains uncertain. In symptomatic subjects, TM hardness correlates with decreased transverse cervical artery (TCA) blood flow to the TM. Neck and upper-back stiffness could be associated with both hemodynamic and neurological factors affecting the TM. We therefore sonographically evaluated structural factors around the accessory nerve innervating the TM impacting neck and upper-back stiffness.

METHODS

Participants comprised 69 healthy young adults (33 men, 36 women; 21 ± 1 y) who completed questionnaires and underwent elastography to determine TM hardness as a strain ratio and pulsed Doppler sonography to determine TCA hemodynamics. Intermuscular length was measured as the distance between sternocleidomastoid and levator scapulae muscles around the accessory nerve. Relationships of intermuscular length with symptoms, TM hardness, and TCA hemodynamics were analyzed.

RESULTS

Intermuscular length was greater in symptomatic subjects (median 2.3 mm, interquartile range 1.5-3.1 mm) than in asymptomatic subjects (median 1.8 mm, interquartile range 1.5-2.3 mm; p = 0.032). Intermuscular length correlated positively with symptom severity (r = 0.43, p = 0.014) and negatively with strain ratio for the TM (r = -0.39, p = 0.025) and peak systolic velocity in the TCA (r = -0.40, p = 0.022). Intermuscular length contributed independently to the presence of symptoms (p = 0.025, odds ratio 2.26, 95% confidence interval 1.11-4.62).

CONCLUSION

In symptomatic subjects, symptom severity, TM hardness and TCA hemodynamics all correlated with greater intermuscular length. Structures around the accessory nerve could be associated with the pathogenesis of essential neck and upper-back stiffness.

Evaluation of curcumin intake in reducing exercise-induced muscle damage in athletes: a systematic review

BACKGROUND

Sports practice, particularly eccentric exercises, induces significant muscular changes, including muscle fiber injuries, strength loss, pain, and increased permeability of the muscle membrane. The duration of muscle recovery depends on factors such as exercise intensity and the specific muscle groups engaged. The inflammatory response plays a crucial role in muscle regeneration, involving various cell types. Curcumin, especially when its stability is enhanced through encapsulation, exhibits potent antioxidant and anti-inflammatory properties. Supplementing with curcumin can reduce muscle damage and inflammation caused by eccentric exercise, making it a potential remedy for athletes.

OBJECTIVE

The objective of this systematic review is to assess the scientific evidence supporting the efficacy of curcumin in reducing muscle damage caused by sports.

METHODS

A structured search in SCOPUS, Medline, and Web of Science databases was conducted in March 2023, including all available articles. The strategy involved selecting English articles without time constraints, using the search terms "curcumin" AND "Exercise-Induced Muscle Damage" (ALL(curcumin AND "Exercise-Induced Muscle Damage")). Titles and abstracts were screened to assess eligibility. Studies were chosen based on PICOS criteria, and quality was evaluated using the reliable PEDro scale. The eligibility criteria included adults without any diagnosed diseases who regularly exercise (at least three times per week) and follow a consistent pattern of curcumin intake before, during, or after exercise.

RESULTS

The comprehensive search identified 11 relevant studies investigating the effects of curcumin supplementation in sport-simulated interventions. These studies suggest that curcumin intake may help reduce muscle symptoms associated with eccentric exercises, thereby improving pain perception. Effective use of curcumin depends on factors such as dosage, bioavailability, and timing, with post-exercise ingestion appearing to be more beneficial.

CONCLUSIONS

Curcumin demonstrates a significant potential to relieve muscle-related symptoms, especially delayed-onset muscle soreness (DOMS) that arises from eccentric exercises, thus potentially improving the well-being of those who are trained. It also appears to have the capability to lower biomarkers associated with inflammation and boost antioxidant levels. Nevertheless, for future studies, the bioavailability of curcumin must be considered, as it is a key factor in its efficacy.

Palmitoylethanolamide Does Not Affect Recovery from Exercise-Induced Muscle Damage in Healthy Males

INTRODUCTION

Strenuous eccentric exercise (EE) induces microstructural muscle damage, which decreases muscle performance. Palmitoylethanolamide (PEA) exerts analgesic and anti-inflammatory effects in clinical pain conditions and preclinical models of experimentally induced inflammation. This might hold clues for improved recovery from EE. Therefore, the current study evaluates the effect of PEA supplementation on functional and molecular responses to a single EE bout.

METHODS

Eleven healthy male participants were included in a double-blind crossover study in which they received PEA (350 mg Levagen+) or placebo (maltodextrin) supplements, in a randomized order. In each experimental condition, participants performed an acute bout of EE (24 × 10 eccentric contractions of the knee extensors on an isokinetic dynamometer). At baseline, 24 (D1), 48 (D2), 72 (D3), and 120 h (D5) following EE, maximal voluntary contraction and jump height were measured. Blood samples were collected at baseline and on D1-D5, and muscle biopsies were collected at baseline and on D2. Perceived muscle soreness, sleep quality, and food intake were recorded daily.

RESULTS

Muscle strength and jump height decreased following EE (up to ~40% and ~17%, respectively; Ptime < 0.05) in both conditions. This drop was accompanied by an increase in plasma creatine kinase and perceived muscle soreness ( Ptime < 0.05). Furthermore, EE, but not PEA, increased the expression of the myogenic marker Pax7 and of the catabolic markers p-FoxO1-3a, p62, and LC3BII/I ( Ptime < 0.05).

CONCLUSIONS

PEA supplementation does not improve muscle soreness, muscle strength, and jump performance following a single EE bout. In addition, PEA supplementation had no effect on local or systemic markers of muscle damage, catabolism, or regeneration.

Skeletal muscle mass, strength, and physical performance gains are similar between healthy postmenopausal women and postmenopausal breast cancer survivors after 12 weeks of resistance exercise training

PURPOSE

Resistance exercise training (RET) effectively increases skeletal muscle mass and strength in healthy postmenopausal women. However, its effects on these parameters in postmenopausal breast cancer survivors are controversial or limited. Therefore, the aim of this study was to compare the effects of a 12-week progressive whole-body RET program on skeletal muscle mass, strength, and physical performance in healthy postmenopausal women versus postmenopausal women who survived breast cancer.

METHODS

Thirteen healthy postmenopausal women (HEA, 54 ± 3 years, BMI 26.6 ± 2.7 kg·m2, n = 13) and eleven postmenopausal breast cancer survivors (BCS, 52 ± 5 years, BMI 26.8 ± 2.1 kg·m2, n = 11) participated in the study. Before and after the RET program, evaluations were performed on quadriceps muscle thickness, one-repetition maximum strength (1RM) for various exercises, grip strength, and physical performance.

RESULTS

Both groups showed significant improvements in quadriceps muscle thickness (time effect, P < 0.001); 1RM strength for leg extension, leg press, chest press, horizontal row, and elbow extension (time effect, all P < 0.001); as well as handgrip strength (time effect, P = 0.035) and physical performance (time effect, all P < 0.001) after the 12-week RET program. There were no significant differences between the groups in response to RET for any of the outcomes measured.

CONCLUSION

Twelve weeks of RET significantly increases skeletal muscle mass, strength, and physical performance in postmenopausal women. No differences were observed between healthy postmenopausal women and postmenopausal breast cancer survivors. These findings point out that this study's RET promotes skeletal muscle mass, strength, and performance gains regardless of breast cancer. Pre-Print Platform Research Square: https://doi.org/10.21203/rs.3.rs-4145715/v1 ; https://www.researchsquare.com/article/rs-4145715/v1 Clinical trial registration: NCT05690295.

Hormones, Hypertrophy, and Hype: An Evidence-Guided Primer on Endogenous Endocrine Influences on Exercise-Induced Muscle Hypertrophy

We review the evidence indicating that endogenous changes in these hormones, including testosterone, growth hormone, insulin growth factor-1, and estrogen, and their proposed anabolic effects contribute to and augment resistance exercise training (RET)-induced hypertrophy. Additionally, we provide recommendations for gold-standard methodological rigor to establish best practices for verifying menstrual phases as part of their research, ultimately enhancing our understanding of the impact of ovarian hormones on RET-induced adaptations.

Countermovement Jump Peak Power Changes with Age in Masters Weightlifters

Aging is associated with decreased muscle strength and power. Power is particularly important for maintaining the independence of older adults when performing activities of daily living. The countermovement jump has been identified as a reliable and safe method to assess lower extremity power across the lifespan. The purpose of this investigation was to study sex differences and age-related changes in countermovement jump peak power among masters weightlifters with the secondary purpose of comparing results to previous reports of community and masters athletes. Female (n = 63, 39 to 70 yrs, med (56 yrs)) and male (n = 39, 35 to 86 yrs, med (59 yrs)) participants of the 2022 World Masters Championships completed three maximal effort countermovement jump repetitions following a dynamic warm-up. Vertical ground reaction forces were recorded, and peak power normalized to body mass was calculated. Results indicated significant age-related peak power among weightlifters, with the decline being significantly more pronounced in males than females. Female weightlifters exhibited less age-related decline compared to normative data as well as the other Master athlete comparison cohorts (short and long-distance runners), whereas the males demonstrated similar age-related declines as the comparison cohorts. While the female weightlifters in the current study generally demonstrated the least age-related declines in CMJ peak power of the comparative literature, the male weightlifters showed similar age-related decline rates.

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.

Sexual dimorphisms in skeletal muscle: current concepts and research horizons

The complex compositional and functional nature of skeletal muscle makes this organ an essential topic of study for biomedical researchers and clinicians. An additional layer of complexity is added with the consideration of sex as a biological variable. Recent research advances have revealed sexual dimorphisms in developmental biology, muscle homeostasis, adaptive responses, and disorders relating to skeletal muscle. Many of the observed sex differences have hormonal and molecular mechanistic underpinnings, whereas others have yet to be elucidated. Future research is needed to investigate the mechanisms dictating sex-based differences in the various aspects of skeletal muscle. As such, it is necessary that skeletal muscle biologists ensure that both female and male subjects are represented in biomedical and clinical studies to facilitate the successful testing and development of therapeutics for all patients.

Time Course of Body Composition Changes in Transgender Adolescents During Puberty Suppression and Sex Hormone Treatment

CONTEXT

Transgender adolescents can undergo puberty suppression (PS) and subsequent gender-affirming hormone therapy (GAHT) but little information is available on the expected rate of physical changes.

OBJECTIVE

To investigate the time course of body composition changes during PS and GAHT.

METHODS

In this study, retrospective data of 380 trans boys and 168 trans girls treated with PS prior to GAHT from a gender identity clinic were included. Total lean and fat mass Z-scores using birth-assigned sex as reference were determined using dual-energy X-ray absorptiometry.

RESULTS

In trans boys, lean mass Z-scores decreased (-0.32, 95% CI -0.41; -0.23) and fat mass Z-scores increased (0.31, 95% CI 0.21; 0.41) in the first year of PS and remained stable thereafter. Lean mass Z-scores increased (0.92, 95% CI 0.81; 1.04) and fat mass Z-scores decreased (-0.43, 95% CI -0.57; -0.29) only during the first year of testosterone,. In trans girls, both lean and fat mass Z-scores gradually changed over 3 years of PS (respectively -1.13, 95% CI -1.29; -0.98 and 1.06, 95% CI 0.90; 1.23). In the first year of GAHT, lean mass Z-scores decreased (-0.19, 95% CI -0.36; -0.03) while fat mass Z-scores remained unchanged after 3 years (-0.02, 95% CI -0.20; 0.16).

CONCLUSION

Compared with peers, trans girls experienced ongoing lean mass decrease and fat mass increase during 3 years of PS while in trans boys smaller changes were observed that stabilized after 1 year. A large increase in lean mass Z-scores occurred only during the first year of testosterone treatment. In trans girls, body composition changed only slightly during GAHT. This information can improve counseling about treatment effects.

Effect of Menstrual Cycle and Hormonal Contraception on Musculoskeletal Health and Performance: Protocol for a Prospective Cohort Design and Cross-Sectional Comparison

BACKGROUND

Women of reproductive age experience cyclical variation in the female sex steroid hormones 17β-estradiol and progesterone during the menstrual cycle that is attenuated by some hormonal contraceptives. Estrogens perform a primary function in sexual development and reproduction but have nonreproductive effects on bone, muscle, and sinew tissues (ie, ligaments and tendons), which may influence injury risk and physical performance.

OBJECTIVE

The purpose of the study is to understand the effect of the menstrual cycle and hormonal contraceptive use on bone and calcium metabolism, and musculoskeletal health and performance.

METHODS

A total of 5 cohorts of physically active women (aged 18-40 years) will be recruited to participate: eumenorrheic, nonhormonal contraceptive users (n=20); combined oral contraceptive pill (COCP) users (n=20); hormonal implant users (n=20); hormonal intrauterine system users (n=20); and hormonal injection users (n=20). Participants must have been using the COCP and implant for at least 1 year and the intrauterine system and injection for at least 2 years. First-void urine samples and fasted blood samples will be collected for biochemical analysis of calcium and bone metabolism, hormones, and metabolic markers. Knee extensor and flexor strength will be measured using an isometric dynamometer, and lower limb tendon and stiffness, tone, and elasticity will be measured using a Myoton device. Functional movement will be assessed using a single-leg drop to assess the frontal plane projection angle and the qualitative assessment of single leg loading. Bone density and macro- and microstructure will be measured using ultrasound, dual-energy x-ray absorptiometry, and high-resolution peripheral quantitative computed tomography. Skeletal material properties will be estimated from reference point indentation, performed on the flat surface of the medial tibia diaphysis. Body composition will be assessed by dual-energy x-ray absorptiometry. The differences in outcome measures between the hormonal contraceptive groups will be analyzed in a one-way between-group analysis of covariance. Within the eumenorrheic group, the influence of the menstrual cycle on outcome measures will be assessed using a linear mixed effects model. Within the COCP group, differences across 2 time points will be analyzed using the paired-samples 2-tailed t test.

RESULTS

The research was funded in January 2020, and data collection started in January 2022, with a projected data collection completion date of August 2024. The number of participants who have consented at the point of manuscript submission is 66. It is expected that all data analysis will be completed and results published by the end of 2024.

CONCLUSIONS

Understanding the effects of the menstrual cycle and hormonal contraception on musculoskeletal health and performance will inform contraceptive choices for physically active women to manage injury risk.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05587920; https://classic.clinicaltrials.gov/ct2/show/NCT05587920.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/50542.

Sex-Based Differences in Muscle Stem Cell Regulation Following Exercise

Sexual dimorphism, driven by the sex hormones testosterone and estrogen, influences body composition, muscle fiber type, and inflammation. Research related to muscle stem cell (MuSC) responses to exercise has mainly focused on males. We propose a novel hypothesis that there are sex-based differences in MuSC regulation following exercise, such that males have more MuSCs, whereas females demonstrate a greater capacity for regeneration.

Preoperative low plasma creatine kinase levels predict worse survival outcomes in bladder cancer after radical cystectomy

BACKGROUND AND AIMS

To evaluate the prognostic significance of preoperative creatine kinase (CK) levels in bladder cancer (BCa) patients who underwent radical cystectomy (RC).

MATERIALS AND METHODS

570 BCa patients with RC were identified between 2010 and 2020. 108.5 U/L of CK levels were defined as the cutoff value. Logistic regression analysis and Cox regression models were performed to evaluate the association between CK levels and oncologic outcomes. Subgroup analyses were performed to address cofounding factors.

RESULTS

Preoperative low CK levels were associated with worse recurrence-free survival (RFS, log-rank P = 0.001) and overall survival (OS, log-rank P = 0.002). Multivariate analysis revealed that preoperative low CK levels were an independent predictor for worse RFS (hazard ratio [HR]: 1.683; P < 0.001) and OS (HR: 1.567; P = 0.002).

CONCLUSIONS

The preoperative low CK level independently predicts worse survival outcomes in BCa after RC. Incorporating it into prediction models might be valuable to assist risk stratification.

Effects of the Menstrual Cycle and Hormonal Contraceptive Use on Metabolic Outcomes, Strength Performance, and Recovery: A Narrative Review

The effects of female sex hormones on optimal performance have been increasingly recognized as an important consideration in exercise and sport science research. This narrative review explores the findings of studies evaluating the effects of menstrual cycle phase in eumenorrheic women and the use of hormonal contraception (oral contraceptives and hormonal intrauterine devices) on metabolism, muscular strength, and recovery in active females. Ovarian hormones are known to influence metabolism because estrogen is a master regulator of bioenergetics. Importantly, the menstrual cycle may impact protein synthesis, impacting skeletal muscle quality and strength. Studies investigating muscular strength in eumenorrheic women report equivocal findings between the follicular phase and luteal phase with no differences compared to oral contraceptive users. Studies examining recovery measures (using biomarkers, blood lactate, and blood flow) do not report clear or consistent effects of the impact of the menstrual cycle or hormonal contraception use on recovery. Overall, the current literature may be limited by the evaluation of only one menstrual cycle and the use of group means for statistical significance. Hence, to optimize training and performance in females, regardless of hormonal contraception use, there is a need for future research to quantify the intra-individual impact of the menstrual cycle phases and hormonal contraceptive use in active females.

Creatine kinase serum levels in children revisited: New reference intervals from a large cohort of healthy children and adolescents

BACKGROUND

Creatine Kinase (CK) has become increasingly important in pediatrics as a commonly used laboratory screening parameter for neuromuscular diseases. Recent research suggests that hyperCKemia in children is not always associated with pathology and can occur due to several reasons. Little is known of various clinical factors that may influence CK throughout child development.

OBJECTIVE

This study aimed to establish reliable age- and sex-specific reference ranges for serum CK levels in healthy infants, children, and adolescents. In addition, the effect of puberty, oral contraceptive (OC) use as well as steroid hormones on CK was examined.

MATERIALS AND METHODS

The data was collected from subjects of the longitudinal population-based "LIFE Child"-cohort between 2011 and 2016 in Leipzig, Germany. 5238 blood samples of 2707 healthy children, aged between 0.14 months and 18 years, were analyzed.

RESULTS

Serum CK levels raised during the first year of life, peaking shortly after age one (P50girls = 2.7 µkat/L, P50boys = 2.90 µkat/L). There was a pronounced difference in the 97.5th percentile between boys and girls during adolescence with its maximum at age 18 (P97.5girls = 5.74 µkat/L, P97.5boys= 14.48 µkat/L). Also, mean CK serum levels were significantly higher in boys (bboys = 0.29, pboys < 0.001). Intake of oral contraceptives (OC), extreme underweight, underweight and obesity revealed a significant inverse correlation with CK serum levels.

CONCLUSION

Age, sex, OC intake and weight status affect serum CK levels, particularly during infancy and puberty. We recommend the use of age- and sex-specific reference values for CK serum levels to assess the clinical relevance of measurements.

Agent-based model demonstrates the impact of nonlinear, complex interactions between cytokinces on muscle regeneration

Muscle regeneration is a complex process due to dynamic and multiscale biochemical and cellular interactions, making it difficult to identify microenvironmental conditions that are beneficial to muscle recovery from injury using experimental approaches alone. To understand the degree to which individual cellular behaviors impact endogenous mechanisms of muscle recovery, we developed an agent-based model (ABM) using the Cellular-Potts framework to simulate the dynamic microenvironment of a cross-section of murine skeletal muscle tissue. We referenced more than 100 published studies to define over 100 parameters and rules that dictate the behavior of muscle fibers, satellite stem cells (SSCs), fibroblasts, neutrophils, macrophages, microvessels, and lymphatic vessels, as well as their interactions with each other and the microenvironment. We utilized parameter density estimation to calibrate the model to temporal biological datasets describing cross-sectional area (CSA) recovery, SSC, and fibroblast cell counts at multiple timepoints following injury. The calibrated model was validated by comparison of other model outputs (macrophage, neutrophil, and capillaries counts) to experimental observations. Predictions for eight model perturbations that varied cell or cytokine input conditions were compared to published experimental studies to validate model predictive capabilities. We used Latin hypercube sampling and partial rank correlation coefficient to identify in silico perturbations of cytokine diffusion coefficients and decay rates to enhance CSA recovery. This analysis suggests that combined alterations of specific cytokine decay and diffusion parameters result in greater fibroblast and SSC proliferation compared to individual perturbations with a 13% increase in CSA recovery compared to unaltered regeneration at 28 days. These results enable guided development of therapeutic strategies that similarly alter muscle physiology (i.e. converting extracellular matrix [ECM]-bound cytokines into freely diffusible forms as studied in cancer therapeutics or delivery of exogenous cytokines) during regeneration to enhance muscle recovery after injury.

Evaluating the effects of hormone therapy termination on skeletal muscle and physical independence in postmenopausal women

OBJECTIVE

In women, the age-related decline in skeletal muscle structure and function is accelerated after menopause, which implicates the role of decreased circulating estrogen levels. Indeed, boosting estrogen, by means of postmenopausal hormone therapy (HT), generally proves beneficial to skeletal muscle. The evidence regarding whether these benefits persist even after cessation of HT is limited, nor is it clear how physical behavior (PB) impacts on benefits. Hence, this exploratory study focused on the interplay between HT administration/cessation, PB and in vivo skeletal muscle structure and function.

METHODS

Fifty healthy women (≥60 y) were included; 19 had an HT administration history (≥9 mo, with now ~8-y hiatus in treatment) and 31 no such history. On seven continuous days, PB data were collected using triaxial accelerometry and analyzed using compositional data analysis. Gastrocnemius medialis muscle volume, architecture, and function were determined using ultrasonography, electromyography, dual x-ray absorptiometry, and dynamometry. Current serum estradiol levels were measured using ELISA.

RESULTS

Only fascicle length and duration of HT administration were positively associated. With respect to PB levels, we found a pattern suggesting greater vitality (higher physical activity and lower sedentarism) in previous HT users, compared with nonusers, despite the two groups currently no longer exhibiting significantly different levels of circulating estradiol.

CONCLUSIONS

After an 8-year hiatus in treatment, HT provides limited advantages in gastrocnemius medialis muscle properties. Interestingly, it perhaps enhances vitality despite prolonged cessation, which in the longer term would facilitate greater physical independence, especially considering the association of sedentary behavior with greater frailty.

Gender Differences in the Impact of a High-Fat, High-Sugar Diet in Skeletal Muscles of Young Female and Male Mice

In the context of the increasing number of obese individuals, a major problem is represented by obesity and malnutrition in children. This condition is mainly ascribable to unbalanced diets characterized by high intakes of fat and sugar. Childhood obesity and malnutrition are not only associated with concurrent pathologies but potentially compromise adult life. Considering the strict correlation among systemic metabolism, obesity, and skeletal muscle health, we wanted to study the impact of juvenile malnutrition on the adult skeletal muscle. To this aim, 3-week-old C56BL/6 female and male mice were fed for 20 weeks on a high-fat. high-sugar diet, and their muscles were subjected to a histological evaluation. MyHCs expression, glycogen content, intramyocellular lipids, mitochondrial activity, and capillary density were analyzed on serial sections to obtain the metabolic profile. Our observations indicate that a high-fat, high-sugar diet alters the metabolic profile of skeletal muscles in a sex-dependent way and induces the increase in type II fibers, mitochondrial activity, and lipid content in males, while reducing the capillary density in females. These data highlight the sex-dependent response to nutrition, calling for the development of specific strategies and for a systematic inclusion of female subjects in basic and applied research in this field.

Time course changes in in vivo muscle mechanical function and Ca2+ regulation of force following experimentally induced gradual ovarian failure in mice

The abrupt cessation of ovarian hormone release is associated with declines in muscle contractile function, yet the impact of gradual ovarian failure on muscle contractility across peri-, early- and late-stage menopause remains unclear. In this study, a 4-vinylcyclohexene diepoxide (VCD)-induced ovarian failure mouse model was used to examine time course changes in muscle mechanical function. Plantar flexors of female mice (VCD: n = 10; CON: n = 8) were assessed at 40 (early perimenopause), 80 (late perimenopause), 120 (menopause onset) and 176 (late menopause) days post-initial VCD injection. A torque-frequency relationship was established across a range of frequencies (10-200 Hz). Isotonic dynamic contractions were elicited against relative loads (10-80% maximal isometric torque) to determine the torque-velocity-power relationship. Mice then performed a fatigue task using intermittent 100 Hz isometric contractions until torque dropped by 60%. Recovery of twitch, 10 Hz and 100 Hz torque were tracked for 10 min post-task failure. Additionally, intact muscle fibres from the flexor digitorum brevis underwent a fatigue task (50 repetitions at 70 Hz), and 10 and 100 Hz tetanic [Ca2+] were monitored for 10 min afterward. VCD mice exhibited 16% lower twitch torque than controls across all time points. Apart from twitch torque, 10 Hz torque and 10 Hz tetanic [Ca2+], where VCD showed greater values relative to pre-fatigue during recovery, no significant differences were observed between control and VCD mice during recovery. These results indicate that gradual ovarian failure has minimal detriments to in vivo muscle mechanical function, with minor alterations observed primarily for low-frequency stimulation during recovery from fatigue.

Effect of a graded running race on lower limb muscle damage, jump performance and muscle soreness in men and women

PURPOSE

Delayed structural and functional recovery after a 20 km graded running race was analyzed with respect to the sex effect.

METHODS

Thirteen female and 14 male recreational runners completed the race and three test sessions: one before (PRE) and two after, once on Day 1 or 2 (D1-2) and then on Day 3 or 4 (D3-4). Muscle damage was assessed indirectly using ultrasonography to quantify changes in cross-sectional area (CSA) of 10 lower-limb muscles. Delayed onset of muscle soreness (DOMS) was assessed for three muscle groups. Functional recovery was quantified by kinetic analysis of a squat jump (SJ) and a drop jump (DJ) test performed on a sledge ergometer. Linear mixed models were used to assess control group reproducibility and recovery patterns according to sex.

RESULTS

Regardless of sex, DOMS peaked at D1-2 for all muscle groups and resolved at D3-4. CSA was increased in each muscle group until D3-4, especially in the semimembranosus muscle. A specific increase was found in the short head of the biceps femoris in women. Regardless of sex, SJ and DJ performances declined up to D3-4. Depending on the muscle, positive and/or negative correlations were found between structural and functional changes. Some of these were sex-specific.

CONCLUSION

Structural and functional recovery was incomplete in both sexes up to D3-4, although DOMS had disappeared. More emphasis should be placed on hamstring muscle recovery. Highlighting the intermuscular compensations that can occur during multi-joint testing tasks, the structural-functional relationships were either positive or negative, muscle- and sex-dependent.

Decreased rotator cuff muscle cross-sectional areas in subjects with adhesive capsulitis: a study comparing male and female subjects

OBJECTIVE

To compare rotator cuff (RC) muscle cross-sectional areas (CSA) in subjects with adhesive capsulitis (AC) to age- and sex-matched controls.

MATERIALS AND METHODS

We retrospectively analyzed 97 shoulder MRIs or MR arthrography studies, of which 42 were clinically diagnosed with AC (27 female, 15 male) and 55 were age- and sex-matched controls (38 female, 17 male). All AC subjects underwent imaging ≥ 6 months after symptom onset. All imaging was examined to exclude RC full-thickness tears and prior surgery. A standardized T1 sagittal MR image was segmented in each subject to obtain the CSA of subscapularis (SSC), supraspinatus (SSP), and infraspinatus (ISP) muscles. Differences in CSAs between AC and control subjects were analyzed by sex (females and males separately) and all subjects combined.

RESULTS

AC females had significantly decreased SSC (P = 0.002) and total (P = 0.006) CSAs compared to controls. Male AC subjects showed decreased SSC (P = 0.044), SSP (P = 0.001), and total (P = 0.005) CSAs. Across all subjects, male and female, the AC cohort had significantly decreased SSC (P = 0.019) and total (P = 0.029) CSAs compared to controls.

CONCLUSION

Decreased RC muscle CSAs were present in AC subjects with ≥ 6 months of symptom duration, with decreased SSC and total CSAs in male and female subjects, and decreased SSP CSA in males.

Diffusion tensor imaging combined with chemical shift-encoded sequence to quantify the adaptive changes of calf muscles in amateur marathoners

PURPOSE

Calf muscles play an important role in marathon race, and the incidence of injury is high in this process. This study prospectively quantified diffusion tensor metrics, muscle fat fraction (MFF) and cross-sectional area (CSA) of calf muscles induced by endurance exercise in amateur marathoners, and the potential mechanisms underlying the changes in these parameters were analyzed.

METHOD

In this prospective study, 35 marathoners (27 males, 8 females; mean age (standard deviation, SD), 38.92 (4.83) years) and 26 controls (18 males, 8 females; mean age (SD), 38.35 (6.75) years) underwent magnetic resonance imaging (MRI) from September 2022 to March 2023. The diffusion tensor eigenvalues (λ1, λ2, λ3), radial diffusivity (RD), fractional anisotropy (FA), MFF and CSA of calf muscles were compared between marathoners and controls. A binary logistic regression model with gender correction was performed analyze the relationship between marathon exercise and DTI parameters, CSA and MFF of calf muscles.

RESULTS

Interobserver agreement was good (κ = 0.71). The results of binary logistic regression model with gender correction showed that the regression coefficients of FA values in anterior group of calf (AC), soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) were negative, and the odds ratios (OR) were 0.33, 0.45, 0.35, 0.05, respectively (P < 0.05). The OR of RD in SOL and λ2 in external group of calf (EC) were relatively higher, 3.74 and 3.26, respectively (P < 0.05). CSA was greater in SOL of marathoners, with an OR value of 1.00(P < 0.05). The MFF in AC and LG was lower in marathoners and OR of two indexes were -0.69 and -0.59, respectively (P < 0.05).

CONCLUSIONS

Diffusion tensor imaging (DTI) combined with chemical shift-encoded sequence can noninvasively detect and quantify the adaptive changes of calf muscle morphology, microstructure and tissue composition induced by long-term running training in amateur marathoners.

Agent-based model demonstrates the impact of nonlinear, complex interactions between cytokines on muscle regeneration

Muscle regeneration is a complex process due to dynamic and multiscale biochemical and cellular interactions, making it difficult to identify microenvironmental conditions that are beneficial to muscle recovery from injury using experimental approaches alone. To understand the degree to which individual cellular behaviors impact endogenous mechanisms of muscle recovery, we developed an agent-based model (ABM) using the Cellular Potts framework to simulate the dynamic microenvironment of a cross-section of murine skeletal muscle tissue. We referenced more than 100 published studies to define over 100 parameters and rules that dictate the behavior of muscle fibers, satellite stem cells (SSC), fibroblasts, neutrophils, macrophages, microvessels, and lymphatic vessels, as well as their interactions with each other and the microenvironment. We utilized parameter density estimation to calibrate the model to temporal biological datasets describing cross-sectional area (CSA) recovery, SSC, and fibroblast cell counts at multiple time points following injury. The calibrated model was validated by comparison of other model outputs (macrophage, neutrophil, and capillaries counts) to experimental observations. Predictions for eight model perturbations that varied cell or cytokine input conditions were compared to published experimental studies to validate model predictive capabilities. We used Latin hypercube sampling and partial rank correlation coefficient to identify in silico perturbations of cytokine diffusion coefficients and decay rates to enhance CSA recovery. This analysis suggests that combined alterations of specific cytokine decay and diffusion parameters result in greater fibroblast and SSC proliferation compared to individual perturbations with a 13% increase in CSA recovery compared to unaltered regeneration at 28 days. These results enable guided development of therapeutic strategies that similarly alter muscle physiology (i.e. converting ECM-bound cytokines into freely diffusible forms as studied in cancer therapeutics or delivery of exogenous cytokines) during regeneration to enhance muscle recovery after injury.

Impact of Menstrual cycle-based Periodized training on Aerobic performance, a Clinical Trial study protocol-the IMPACT study

BACKGROUND

The menstrual cycle and its impact on training and performance are of growing interest. However, evidence is lacking whether periodized exercise based on the menstrual cycle is beneficial. The primary purpose of this proposed randomized, controlled trial, the IMPACT study, is to evaluate the effect of exercise periodization during different phases of the menstrual cycle, i.e., comparing follicular phase-based and luteal phase-based training with regular training during the menstrual cycle on physical performance in well-trained women.

METHODS

Healthy, well-trained, eumenorrheic women between 18 and 35 years (n = 120) will be recruited and first assessed for physical performance during a run-in menstrual cycle at different cycle phases and then randomized to three different interventions: follicular phase-based training, luteal phase-based training, or regular training during three menstrual cycles. The training intervention will consist of high-intensity spinning classes followed by strength training. The menstrual cycle phases will be determined by serum hormone analysis throughout the intervention period. Assessment of aerobic performance (primary outcome) and muscle strength, body composition, and blood markers will be performed at baseline and at the end of the intervention.

DISCUSSION

With a robust methodology, this study has the potential to provide evidence of the differential effects of exercise periodization during different phases of the menstrual cycle in female athletes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05697263 . Registered on 25 January 2023.

Impact of the Menstrual Cycle on Physical Performance and Subjective Ratings in Elite Academy Women Soccer Players

Our study aimed to combine psychological and physical factors to explore the impact of the menstrual cycle on performance in elite academy women soccer players through weekly monitoring. Eighteen elite academy women soccer players were monitored. Players reported daily through an online anonymous survey if they were in menstruation. Players answered the Hooper Questionnaire daily, performed an Illinois Agility Test (IAT) twice a week, and rated their perceived exertion (RPE) after every training session. Tests were associated with a complete menstrual cycle reported through the online anonymous survey to determine the two weeks of the follicular phase and the two weeks of the luteal phase. Of the 18 players, 10 completed all requirements and were retained for analyses. IAT did not show significant differences throughout the menstrual cycle (p = 0.633). Fatigue (p = 0.444), Stress (p = 0.868), Sleep (p = 0.398), DOMS (delayed onset muscle soreness; p = 0.725), and Hooper Index (p = 0.403) did not show significant differences either. RPE was also comparable across the cycle (p = 0.846). Our results failed to demonstrate that hormonal variation during the menstrual cycle influenced psychological and physical markers of performance.

The contribution of mitochondria to age-related skeletal muscle wasting: A sex-specific perspective

As people age, their skeletal muscle (SkM) experiences a decline in mitochondrial functionality and density, which leads to decreased energy production and increased generation of reactive oxygen species. This cascade of events, in turn, might determine the loss of SkM mass, strength and quality. Even though the mitochondrial processes dysregulated by aging, such as oxidative phosphorylation, mitophagy, antioxidant defenses and mtDNA transcription, are the same in both sexes, mitochondria age differently in the SkM of men and women. Indeed, the onset and magnitude of the impairment of these processes seem to be influenced by sex-specific factors. Sexual hormones play a pivotal role in the regulation of SkM mass through both genomic and non-genomic mechanisms. However, the precise mechanisms by which these hormones regulate mitochondrial plasticity in SkM are not fully understood. Although the presence of estrogen receptors in mitochondria is recognized, it remains unclear whether androgen receptors affect mitochondrial function. This comprehensive review critically dissects the current knowledge on the interplay of sex in the aging of SkM, focusing on the role of sex hormones and the corresponding signaling pathways in shaping mitochondrial plasticity. Improved knowledge on the sex dimorphism of mitochondrial aging may lead to sex-tailored interventions that target mitochondrial health, which could be effective in slowing or preventing age-related muscle loss.

The Effect of Caffeine Supplementation on Female Volleyball Players' Performance and Wellness during a Regular Training Week

BACKGROUND

caffeine is an ergogenic aid that still needs to be investigated in women's sports performance.

METHODS

Eight semi-professional women's volleyball players (height = 1.63 ± 0.08 m; weight = 66.67 ± 4.74 kg) voluntarily participated in this study. A randomized crossover design was implemented where players underwent caffeine and placebo conditions. In the caffeine condition, participants consumed 5 mg/kg of caffeine based on their body weight before acute training. The evaluations were performed over two weeks of training. In both conditions, the countermovement jump, repeated jumps for 15 s, and handgrip tests were performed. The change of direction was assessed using the 505 test. Well-being was also assessed with a wellness questionnaire. A repeated measures ANOVA and correlation analysis were performed.

RESULTS

The repeated measures ANOVA revealed a main effect of supplementation (F (1.7) = 8.41, p = 0.02, η2 = 0.54) across the training week on physical performance. Additionally, there was a positive effect on perceived fatigue (F (1.7) = 7.29, p = 0.03, η2 = 0.51).

CONCLUSIONS

Caffeine improved performance and fatigue parameters over one week of training. Further research is needed on women, focusing on physical performance and wellbeing, especially during intense periods.

Exercise and Caloric Restriction Exert Different Benefits on Skeletal Muscle Metabolism in Aging Condition

Exercise and caloric restriction improve skeletal muscle metabolism. However, the benefits of exercise and caloric restriction on skeletal muscle metabolism in aging have never been compared. Seven-week-old male Wistar rats (n = 24) were divided into 4 groups (n = 6 per group) to receive either normal saline solution for 28 weeks, 150 mg/kg/day of D-galactose for 28 weeks to induce premature aging, 150 mg/kg/day of D-galactose for 28 weeks plus exercise for 16 weeks (week 13-28), or 150 mg/kg/day of D-galactose for 28 weeks plus 30% caloric restriction for 16 weeks (week 13-28). The 17-month-old rats (n = 6) were also injected with normal saline solution for 28 weeks as the naturally aged controls. At the end of week 28, total walking distance and fatty acid and carbohydrate oxidation during physical activity were determined. Then, all rats were euthanized for the collection of blood and tibialis anterior muscle. The results showed that D-galactose successfully mimicked the natural aging of skeletal muscle. Exercise and caloric restriction equally improved carbohydrate oxidation during physical activity and myogenesis. However, exercise was superior to caloric restriction in terms of improving fatty acid oxidation and oxidative phosphorylation. Interestingly, caloric restriction decreased oxidative stress, whereas exercise increased oxidative stress of skeletal muscle. All of these findings indicated that the benefits of exercise and caloric restriction on skeletal muscle metabolism during aging were different, and therefore the combination of exercise and caloric restriction might provide greater efficacy in ameliorating skeletal muscle aging.

Menstrual cycle hormones and oral contraceptives: a multimethod systems physiology-based review of their impact on key aspects of female physiology

Hormonal changes around ovulation divide the menstrual cycle (MC) into the follicular and luteal phases. In addition, oral contraceptives (OCs) have active (higher hormone) and placebo phases. Although there are some MC-based effects on various physiological outcomes, we found these differences relatively subtle and difficult to attribute to specific hormones, as estrogen and progesterone fluctuate rather than operating in a complete on/off pattern as observed in cellular or preclinical models often used to substantiate human data. A broad review reveals that the differences between the follicular and luteal phases and between OC active and placebo phases are not associated with marked differences in exercise performance and appear unlikely to influence muscular hypertrophy in response to resistance exercise training. A systematic review and meta-analysis of substrate oxidation between MC phases revealed no difference between phases in the relative carbohydrate and fat oxidation at rest and during acute aerobic exercise. Vascular differences between MC phases are also relatively small or nonexistent. Although OCs can vary in composition and androgenicity, we acknowledge that much more work remains to be done in this area; however, based on what little evidence is currently available, we do not find compelling support for the notion that OC use significantly influences exercise performance, substrate oxidation, or hypertrophy. It is important to note that the study of females requires better methodological control in many areas. Previous studies lacking such rigor have contributed to premature or incorrect conclusions regarding the effects of the MC and systemic hormones on outcomes. While we acknowledge that the evidence in certain research areas is limited, the consensus view is that the impact of the MC and OC use on various aspects of physiology is small or nonexistent.

The Biological Basis of Sex Differences in Athletic Performance: Consensus Statement for the American College of Sports Medicine

ABSTRACT

Biological sex is a primary determinant of athletic performance because of fundamental sex differences in anatomy and physiology dictated by sex chromosomes and sex hormones. Adult men are typically stronger, more powerful, and faster than women of similar age and training status. Thus, for athletic events and sports relying on endurance, muscle strength, speed, and power, males typically outperform females by 10%-30% depending on the requirements of the event. These sex differences in performance emerge with the onset of puberty and coincide with the increase in endogenous sex steroid hormones, in particular testosterone in males, which increases 30-fold by adulthood, but remains low in females. The primary goal of this consensus statement is to provide the latest scientific knowledge and mechanisms for the sex differences in athletic performance. This review highlights the differences in anatomy and physiology between males and females that are primary determinants of the sex differences in athletic performance and in response to exercise training, and the role of sex steroid hormones (particularly testosterone and estradiol). We also identify historical and nonphysiological factors that influence the sex differences in performance. Finally, we identify gaps in the knowledge of sex differences in athletic performance and the underlying mechanisms, providing substantial opportunities for high-impact studies. A major step toward closing the knowledge gap is to include more and equitable numbers of women to that of men in mechanistic studies that determine any of the sex differences in response to an acute bout of exercise, exercise training, and athletic performance.

Probing muscle recovery following downhill running using precise mapping of MRI T2 relaxation times

PURPOSE

Postexercise recovery rate is a vital component of designing personalized training protocols and rehabilitation plans. Tracking exercise-induced muscle damage and recovery requires sensitive tools that can probe the muscles' state and composition noninvasively.

METHODS

Twenty-four physically active males completed a running protocol consisting of a 60-min downhill run on a treadmill at -10% incline and 65% of maximal heart rate. Quantitative mapping of MRI T2 was performed using the echo-modulation-curve algorithm before exercise, and at two time points: 1 h and 48 h after exercise.

RESULTS

T2 values increased by 2%-4% following exercise in the primary mover muscles and exhibited further elevation of 1% after 48 h. For the antagonist muscles, T2 values increased only at the 48-h time point (2%-3%). Statistically significant decrease in the SD of T2 values was found following exercise for all tested muscles after 1 h (16%-21%), indicating a short-term decrease in the heterogeneity of the muscle tissue.

CONCLUSION

MRI T2 relaxation time constitutes a useful quantitative marker for microstructural muscle damage, enabling region-specific identification for short-term and long-term systemic processes, and sensitive assessment of muscle recovery following exercise-induced muscle damage. The variability in T2 changes across different muscle groups can be attributed to their different role during downhill running, with immediate T2 elevation occurring in primary movers, followed by delayed elevation in both primary and antagonist muscle groups, presumably due to secondary damage caused by systemic processes.

Sarcopenia, a condition shared by various diseases: can we alleviate or delay the progression?

Sarcopenia is a severe condition common to various chronic diseases and it is reckoned as a major health problem. It encompasses many different molecular mechanisms that have been for a while discovered but not definitely clarified. Although sarcopenia is a disability status that leads to serious health consequences, the scarcity of suitable animal models has curtailed research addressing this disorder. Another limitation in the field of clinical investigation of sarcopenic patients is the lack of a generally accepted definition coupled with the difficulty of adopting common diagnostic criteria. In fact, both do not permit to clarify the exact prevalence rate and consequently limit physicians to establish any kind of therapeutical approach or, when possible, to adopt preventive measures. Unfortunately, there is no standardized cure, apart from doing more physical activity and embracing a balanced diet, but newly discovered substances start being considered. In this review, authors try to give an overview addressing principal pathways of sarcopenia and offer critical features of various possible interventions.

Understanding the development of sarcopenic obesity

INTRODUCTION

Sarcopenic obesity (SarcO) is defined as the confluence of reduced muscle mass and function and excess body fat. The scientific community is increasingly recognizing this syndrome, which affects a subgroup of persons across their lifespans and places them at synergistically higher risk of significant medical comorbidity and disability than either sarcopenia or obesity alone. Joint efforts in clinical and research settings are imperative to better understand this syndrome and drive the development of urgently needed future interventions.

AREAS COVERED

Herein, we describe the ongoing challenges in defining sarcopenic obesity and the current state of the science regarding its epidemiology and relationship with adverse events. The field has demonstrated an emergence of data over the past decade which we will summarize in this article. While the etiology of sarcopenic obesity is complex, we present data on the underlying pathophysiological mechanisms that are hypothesized to promote its development, including age-related changes in body composition, hormonal changes, chronic inflammation, and genetic predisposition.

EXPERT OPINION

We describe emerging areas of future research that will likely be needed to advance this nascent field, including changes in clinical infrastructure, an enhanced understanding of the lifecourse, and potential treatments.

Sexual Dimorphism of Skeletal Muscle in a Mouse Model of Breast Cancer: A Functional and Molecular Analysis

Breast cancer incidence in men is statistically rare; however, given the lack of screening in males, more advanced stages at initial diagnosis result in lower 5-year survival rates for men with breast cancer compared to women. A sexual dimorphism, with respect to the effect of tumor growth on cachexia incidence and severity, has also been reported across cancer types. The purpose of this study was to examine the sexual dimorphism of breast cancer as it pertains to skeletal muscle function and molecular composition. Using female and male transgenic PyMT mice, we tested the hypothesis that the isometric contractile properties and molecular composition of skeletal muscle would be differentially affected by breast tumors. PyMT tumor-bearing mice of each sex, corresponding to maximal tumor burden, were compared to their respective controls. RNA sequencing of skeletal muscle revealed different pathway alterations that were exclusive to each sex. Further, differentially expressed genes and pathways were substantially more abundant in female tumor mice, with only minimal dysregulation in male tumor mice, each compared to their respective controls. These differences in the transcriptome were mirrored in isometric contractile properties, with greater tumor-induced dysfunction in females than male mice, as well as muscle wasting. Collectively, these data support the concept of sexually dimorphic responses to cancer in skeletal muscle and suggest that these responses may be associated with the clinical differences in breast cancer between the sexes. The identified sex-dependent pathways within the muscle of male and female mice provide a framework to evaluate therapeutic strategies targeting tumor-associated skeletal muscle alterations.

Sexual Dimorphism of Skeletal Muscle in a Mouse Model of Breast Cancer: A Functional and Molecular Analysis

Breast cancer incidence in men is statistically rare; however, given the lack of screening in males, more advanced stages at initial diagnosis results in lower 5-year survival rates for men with breast cancer compared to women. A sexual dimorphism, with respect to the effect of tumor growth on cachexia incidence and severity, has also been reported across cancer types. The purpose of this study was to examine the sexual dimorphism of breast cancer as it pertains to skeletal muscle function and molecular composition. Using female and male transgenic PyMT mice, we tested the hypothesis that isometric contractile properties and molecular composition of skeletal muscle would be differentially affected by breast tumors. PyMT tumor-bearing mice of each sex, corresponding to maximal tumor burden, were compared to their respective controls. RNA-sequencing of skeletal muscle revealed different pathway alterations that were exclusive to each sex. Further, differentially expressed genes and pathways were substantially more abundant in female tumor mice, with only minimal dysregulation in male tumor mice, each compared to their respective controls. These differences in the transcriptome were mirrored in isometric contractile properties, with greater tumor-induced dysfunction in females than male mice, as well as muscle wasting. Collectively, these data support the concept of sexually dimorphic responses to cancer in skeletal muscle and suggest these responses may be associated with the clinical differences in breast cancer between the sexes. The identified sex-dependent pathways within muscle of male and female mice provide a framework to evaluate therapeutic strategies targeting tumor-associated skeletal muscle alterations.

Understanding the female athlete: molecular mechanisms underpinning menstrual phase differences in exercise metabolism

Research should equitably reflect responses in men and women. Including women in research, however, necessitates an understanding of the ovarian hormones and menstrual phase variations in both cellular and systems physiology. This review outlines recent advances in the multiplicity of ovarian hormone molecular signaling that elucidates the mechanisms for menstrual phase variability in exercise metabolism. The prominent endogenous estrogen, 17-β-estradiol (E2), molecular structure is bioactive in stabilizing plasma membranes and quenching free radicals and both E2 and progesterone (P4) promote the expression of antioxidant enzymes attenuating exercise-induced muscle damage in the late follicular (LF) and mid-luteal (ML) phases. E2 and P4 bind nuclear hormone receptors and membrane-bound receptors to regulate gene expression directly or indirectly, which importantly includes cross-regulated expression of their own receptors. Activation of membrane-bound receptors also regulates kinases causing rapid cellular responses. Careful analysis of these signaling pathways explains menstrual phase-specific differences. Namely, E2-promoted plasma glucose uptake during exercise, via GLUT4 expression and kinases, is nullified by E2-dominant suppression of gluconeogenic gene expression in LF and ML phases, ameliorated by carbohydrate ingestion. E2 signaling maximizes fat oxidation capacity in LF and ML phases, pending low-moderate exercise intensities, restricted nutrient availability, and high E2:P4 ratios. P4 increases protein catabolism during the luteal phase by indeterminate mechanisms. Satellite cell function supported by E2-targeted gene expression is countered by P4, explaining greater muscle strengthening from follicular phase-based training. In totality, this integrative review provides causative effects, supported by meta-analyses for quantitative actuality, highlighting research opportunities and evidence-based relevance for female athletes.

The Behavior of Muscle Oxygen Saturation, Oxy and Deoxy Hemoglobin during a Fatigue Test in Fibromyalgia

Previous studies have reported that people with fibromyalgia (FM) could suffer from mitochondrial dysfunction. However, the consumption of muscle oxygen during physical exercise has been poorly studied. Therefore, this study aimed to explore the response of muscle oxygen during a fatigue protocol in people with FM and healthy controls (HC). In addition, the peak torque and the total work were assessed. A total of 31 participants (eighteen were people with fibromyalgia and thirteen were healthy controls) were enrolled in this cross-sectional study. All the participants underwent a fatigue protocol consisting of 20 repetitions at 180°·s−1 of quadriceps flexions and extensions using a Biodex System 3. The muscle oxygen saturation (SmO2), total hemoglobin (THb), deoxygenated hemoglobin (HHb) and oxygenated hemoglobin (O2Hb) values were measured using a portable near-infrared spectroscopy (NIRS) device. Significant differences between people with FM and healthy controls were found at baseline: SmO2 (FM: 56.03 ± 21.36; HC: 77.41 ± 10.82; p = 0.036), O2Hb (FM: 6.69 ± 2.59; HC: 9.37 ± 1.31; p = 0.030) and HHb (FM: 5.20 ± 2.51; HC: 2.73 ± 1.32; p = 0.039); during the fatigue protocol: SmO2 (FM: 48.54 ± 19.96; HC: 58.87 ± 19.72; p = 0.038), O2Hb (FM: 5.70 ± 2.34; HC: 7.06 ± 2.09; p = 0.027) and HHb (FM: 5.69 ± 2.65; HC: 4.81 ± 2.39; p = 0.048); and in the recovery at three min and six min for SmO2, O2Hb and HHb (p < 0.005). Furthermore, healthy control values of SmO2, O2Hb and HHb have been significantly altered by the fatigue protocol (p < 0.005). In contrast, people with FM did not show any significant alteration in these values. Moreover, significant differences were found in the peak torque at extension (FM: 62.48 ± 24.45; HC: 88.31 ± 23.51; p = 0.033) and flexion (FM: 24.16 ± 11.58; HC: 42.05 ± 9.85; p = 0.010), and the total work performed at leg extension (FM: 1039.78 ± 434.51; HC: 1535.61 ± 474.22; p = 0.007) and flexion (FM: 423.79 ± 239.89; HC: 797.16 ± 194.37; p = 0.005).

Current evidence shows no influence of women's menstrual cycle phase on acute strength performance or adaptations to resistance exercise training

Introduction

The bias towards excluding women from exercise science research is often due to the assumption that cyclical fluctuations in reproductive hormones influence resistance exercise performance and exercise-induced adaptations.

Methods

Hence, the purpose of this umbrella review was to examine and critically evaluate the evidence from meta-analyses and systematic reviews on the influence of menstrual cycle phase on acute performance and chronic adaptations to resistance exercise training (RET).

Results

We observed highly variable findings among the published reviews on the ostensible effects of female sex hormones on relevant RET-induced outcomes, including strength, exercise performance, and hypertrophy.

Discussion

We highlight the importance of comprehensive menstrual cycle verification methods, as we noted a pattern of poor and inconsistent methodological practices in the literature. In our opinion, it is premature to conclude that short-term fluctuations in reproductive hormones appreciably influence acute exercise performance or longer-term strength or hypertrophic adaptations to RET.

The Relationship Between Menopause and Dysphagia: A Scoping Review

Purpose

Menopause marks the end of fertility and rapid decline of ovarian hormones in the female body, which corresponds to a myriad of changes to bodily systems, including the upper aerodigestive tract. Despite substantial evidence that menopause negatively impacts oral health, bones, and skeletal muscles, little research has examined these effects as they relate to swallowing. The purpose of this scoping review was to compile and summarize the existing literature investigating the relationship between menopause and swallowing-related structures and physiology.

Methods

Search terms were selected for three databases (PubMed, Scopus, and CINAHL) to gather relevant literature evaluating the relationship between menopause and swallowing-related anatomy as well as swallowing functions in both human and animal models. Relevant articles were reviewed, collated, and summarized to synthesize findings, identify gaps in the literature, and provide suggestions for future directions.

Results

This scoping review yielded 204 studies with the majority of these studies relating to one or more of the following categories: oral health, saliva, mandibular structures, and taste. Common oral symptoms reported in the literature included xerostomia, hyposalivation, tooth decay, inflammation of oral mucosa, and oral pain. Although literature supports that menopause adversely affects oral health, saliva, mandibular structures, and alters taste, a dearth of information was evident regarding how these hormone-dependent changes can adversely affect swallowing.

Conclusions

The relationship between menopause and swallowing has been overlooked by field of speech-language pathology. By identifying the major gaps in the literature, these results will inform future investigations evaluating relationships among ovarian hormones and swallowing.

Motor Control and Regularity of Menstrual Cycle in Ankle and Knee Injuries of Female Basketball Players: A Cohort Study

Inadequate motor control facilitates ankle and knee injuries in female basketball. Although biomechanical analysis could help to detect it, aspects such as irregular menstruation make these associations controversial. We aimed to evaluate associations between 2D biomechanics during landing and proprioception with ankle and knee injuries of female basketball players, considering their menstruation regularity. Seventy-one players participated in this study. In the preseason, participants performed a drop-jump to obtain biomechanics during landing and a weight-bearing proprioception test. During the competitive season, all the non-contact ankle and knee injuries were registered. Data showed that 16% of players sustained an ankle or knee injury, being more frequent in players with irregular menstruation compared to regulars (22% vs. 13%, χ² = 6.009, p = 0.050, d = 0.6). Players who sustained a left-side injury displayed higher left-side dynamic valgus during landing than uninjured players (χ² = 25.88, p = 0.006, d = 1.5). The rest of the variables did not show any significant difference (p > 0.05). Monitoring 2D dynamic valgus from a drop-jump could help to detect inadequate motor control that may facilitate ankle or knee injuries of female basketball players, mainly for those with irregular menstruation. Proprioception seems not to be related to injuries.

Potential Application of Low-Intensity Focused Ultrasound in Rapidly Relieving Delayed-Onset Muscle Soreness Induced by High-Intensity Exercise

OBJECTIVES

To evaluate the efficacy of low-intensity focused ultrasound (LIFU) treatment on rapid relief of delayed-onset muscle soreness (DOMS) triggered by high-intensity exercise.

METHODS

A total of 16 healthy male college students were randomly divided into two groups: the LIFU group (n = 8) and the Sham group (n = 8). After the exercise protocol, the LIFU group received treatment, which parameters included that the power output was 2.5 W/cm² , the frequency was 1 MHz, and the treating time was 20 minutes. The Sham group was treated with LIFU without energy output. Visual analog scale was used to evaluate the level of DOMS in every participant. The activities of plasma creatine kinase, lactate dehydrogenase, and the plasma concentration were measured by spectrophotometry. Tumor necrosis factor-α and interleukin-6 of serum were analyzed by enzyme-linked immunosorbent assay.

RESULTS

The visual analog scale of quadriceps femoris and/or calf muscles in the LIFU group decreased significantly at 24 hours (P < 0.01) and 48 hours (P < .01) after the exercise protocol. Both the accumulation of lactic acid (P < .01) in muscle and the activity of lactate dehydrogenase (P < .01) reduced immediately after LIFU treatment. The activities of tumor necrosis factor-α and interleukin-6 24 hours lowered in the LIFU group (P < .01).

CONCLUSIONS

LIFU treatment could relieve muscle soreness rapidly and effectively in the early stages of DOMS. The application of LIFU may provide a potential strategy for clinical treatment for DOMS.

Association between Alcohol Consumption and the Risk of Sarcopenia: A Systematic Review and Meta-Analysis

Sarcopenia is a common disease defined as the loss of skeletal muscle mass, strength, and physical performance. Alcohol consumption is an uncertain risk factor for sarcopenia. Previous observational epidemiological studies have reported inconsistent results regarding the association between alcohol consumption and sarcopenia risk. This study aimed to investigate the association between alcohol consumption and sarcopenia. A literature review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched PubMed, EMBASE, and the Cochrane Library through April 2022 using keywords related to alcohol consumption and sarcopenia. The pooled odds ratio (OR) with a 95% confidence interval (CI) was calculated using a random effects model meta-analysis. The risk of bias of the studies was assessed using the Newcastle−Ottawa scale. Nineteen observational studies that reported 3826 sarcopenia patients among 422,870 participants were included in the qualitative analysis. Alcohol consumption was not significantly associated with sarcopenia risk (OR, 1.00; 95% CI, 0.83 to 1.20; I2 = 60.6%). Alcohol consumption resulted in a non-significant decrease in the risk of sarcopenia in men (OR, 0.70; 95% CI, 0.46 to 1.07; I2 = 0.0%) and in women (OR, 1.20; 95% CI, 0.63 to 2.30; I2 = 75.8%). The subgroup analyses by age and alcohol consumption were significantly associated with an increased the risk of sarcopenia in <65 years (OR, 2.62; 95% CI, 1.22 to 5.62; I2 = 100%). This meta-analysis of observational studies indicated that alcohol consumption was not significantly associated with sarcopenia risk. However, there are factors influencing the association between alcohol consumption and sarcopenia, such as smoking and dietary patterns. Additional study of these confounding factors is needed for the systematic analysis of the association of alcohol consumption with sarcopenia in future studies.

Mechanisms of Estrogen Influence on Skeletal Muscle: Mass, Regeneration, and Mitochondrial Function

Human menopause is widely associated with impaired skeletal muscle quality and significant metabolic dysfunction. These observations pose significant challenges to the quality of life and mobility of the aging population, and are of relevance when considering the significantly greater losses in muscle mass and force-generating capacity of muscle from post-menopausal females relative to age-matched males. In this regard, the influence of estrogen on skeletal muscle has become evident across human, animal, and cell-based studies. Beneficial effects of estrogen have become apparent in mitigation of muscle injury and enhanced post-damage repair via various mechanisms, including prophylactic effects on muscle satellite cell number and function, as well as membrane stability and potential antioxidant influences following injury, exercise, and/or mitochondrial stress. In addition to estrogen replacement in otherwise deficient states, exercise has been found to serve as a means of augmenting and/or mimicking the effects of estrogen on skeletal muscle function in recent literature. Detailed mechanisms behind the estrogenic effect on muscle mass, strength, as well as the injury response are beginning to be elucidated and point to estrogen-mediated molecular cross talk amongst signalling pathways, such as apoptotic signaling, contractile protein modifications, including myosin regulatory light chain phosphorylation, and the maintenance of muscle satellite cells. This review discusses current understandings and highlights new insights regarding the role of estrogen in skeletal muscle, with particular regard to muscle mass, mitochondrial function, the response to muscle damage, and the potential implications for human physiology and mobility.

Influence of Menstrual Cycle on Leukocyte Response Following Exercise-Induced Muscle Damage

We investigated the influence of the menstrual cycle (MC) on leukocyte response after exercise-induced muscle damage (EIMD). During the early follicular (E-FP, n = 12) or mid-luteal phase (M-LP, n = 12), 24 untrained females with eumenorrhea performed 60 eccentric exercises using nondominant arms. Blood samples were collected at pre- and 4, 48, and 96 h postexercise to analyze estradiol and progesterone concentrations, leukocyte count and fractionation, and creatine kinase (CK) activity. We also assessed the maximal voluntary isometric contraction torque of elbow flexion, range of motion in the elbow joint, upper-arm circumference, and muscle soreness as indirect muscle damage markers at pre-; immediately post-; and 4, 48, and 96 h postexercise. The percent change in neutrophil counts from pre- to 4 h postexercise was lower in M-LP than in E-FP (E-FP, 30.7% [15.9–65.7%] vs. M-LP, 10.3% [−2.3–30.0%]; median [interquartile range: 25–75%]; p = 0.068). Progesterone concentration at pre-exercise was significantly negatively correlated with the percent change in neutrophil counts from pre- to 4 h postexercise in M-LP (r = −0.650, p = 0.022). MC did not affect CK activity or other muscle damage markers. Thus, progesterone concentration rather than MC may be related to neutrophil response following EIMD.