Low energy availability (LEA) is a medical condition observed in athletes, with a higher prevalence in aesthetic sports. For the first time, this study evaluated the relative prevalence of LEA in female elite athletes (ELA) and recreational athletes (REA) in aesthetic sports in China. Female athletes from 6 sports (trampolining, rhythmic gymnastics, aerobics, dance sport, cheerleading and dance) were recruited, including ELA (n = 52; age = 20 ± 3) on Chinese national teams and REA (n = 114; Age = 20 ± 2) from Beijing Sport University. Participants completed 2 online questionnaires to assess LEA and eating disorder risk. These included the Low Energy Availability in Females Questionnaire (LEAF-Q), which provided information on injury history, gastrointestinal function and menstrual history, and the Eating Disorder Inventory-3 Referral Form (EDI-3 RF). For a sub-group of elite athletes (n = 14), body composition, bone mineral density, and blood serum were also quantified. A total of 41.6% of participants (n = 69) were at increased risk of LEA, and 57.2% of participants (n = 95) were classified as high in eating disorder risk. For ELA vs. REA, there was a significantly higher prevalence of LEA risk (55.8% vs. 35.1%; p = 0.012) and amenorrhea (53.8% vs. 13.3%; p < 0.001). Elite athletes at increased risk of LEA had significantly lower estradiol (p = 0.021) and whole-body BMD (p = 0.028). Pearson correlations indicated that the whole-body BMD (r = − 0.667, p = 0.009) correlated negatively with LEAF-Q score. Results of this study indicate that there is a risk of LEA in female Chinese athletes within aesthetic sports, and significantly higher prevalence of increased LEA risk observed in ELA than in REA. Chinese coaches and sports medicine staff working elite female athletes in aesthetic sports should develop strategies to reduce the prevalence of LEA.

There is increasing evidence that dietary protein intake with leucine and vitamin D is an important factor in muscle protein synthesis. This study investigated the combined effects of consuming whey protein and vitamin D₃ in the evening before bedtime or in the morning after sleeping on muscle mass and strength. Healthy, untrained males (N = 42; Age = 18–24 year) were randomly assigned into three groups: before bedtime, after sleeping, and control. Subjects underwent a 6-week resistance training program in combination with supplements that provided 25 g whey protein and 4000 IU vitamin D₃ for the before bedtime and after sleeping groups and a 5 g maltodextrin placebo for the control group. A significant increase in serum vitamin D was observed in both before bedtime and after sleeping groups. All groups experienced a significant gain in leg press. However, the control group did not experience significant improvements in muscle mass and associated blood hormones that were experienced by the before bedtime and after sleeping groups. No significant differences in assessed values were observed between the before bedtime and after sleeping groups. These findings suggest that the combination of whey protein and vitamin D supplements provided either before or after sleep resulted in beneficial increases in muscle mass in young males undergoing resistance training that exceeded the changes observed without these supplements.

Background: Recreational exercise has become increasingly common among Chinese adults. However, population-specific data on sweat rate and electrolyte composition during typical daily physical activities remain limited. Therefore, this study aimed to comprehensively characterize the hydration status, sweat rate, and sweat electrolyte composition among Chinese adults engaging in common daily exercises under controlled environmental conditions, and to examine sex-related differences. Methods: In this cross-sectional study, 285 healthy adults (143 men, 142 women) were assigned to one of three separate activity groups: brisk walking (n = 100), running (n = 90), or cycling (n = 95). Activity protocols were standardized using fixed activity-specific speeds corresponding to 5.2, 8.2, and 4.4 METs for brisk walking, running, and cycling, respectively, based on the Chinese Compilation of Physical Activities. Each participant completed one 60-min exercise session under controlled environmental conditions. Sweat samples were collected from the chest using sweat patches and analyzed for Na⁺, K⁺, Ca²⁺, Mg²⁺, Fe, Zn²⁺, and Cu²⁺ using ICP-MS/OES. Whole-body sweat sodium and potassium concentrations were estimated using validated regression equations. Body mass loss (BML) and sweat rate were calculated from pre- and post-exercise nude body mass. Results: Across all participants and activity types, the overall mean sweat rate was 0.71 ± 0.28 L/h, and the mean percentage of body mass loss (BML%) was 0.78 ± 0.45%. Among the three physical activities, running elicited higher sweat rates (0.92 ± 0.29 L/h) and BML% (1.16 ± 0.36%) than brisk walking or cycling (p < 0.05). The estimated whole-body Na⁺ and K⁺ concentrations across all participants were 34.10 ± 10.31 mmol/L and 3.35 (3.02–3.93) mmol/L, respectively, with 59.3% of participants classified as having moderate Na⁺ levels (30–60 mmol/L). Men exhibited higher sweat rates and Na⁺ concentrations, whereas women showed higher K⁺, Zn²⁺, and Cu²⁺ levels (p < 0.05). Conclusions: Chinese adults engaging in common daily physical activities under temperate environmental conditions demonstrated low-to-moderate sweat rates and sodium concentrations. These findings provide baseline reference data for population-specific hydration education and may inform future validation and application of wearable sweat-sensing technologies in public health monitoring.