The influence of low energy availability (LEA) on bone mineral density (BMD) and trabecular bone microarchitecture in pubescent female athletes is unclear. This study aimed to investigate the influence of LEA on BMD and trabecular bone microarchitecture in 21 pubescent female athletes (age, 12–15 years; 11 track and field athletes, 10 gymnasts). We used two indices to assess LEA: energy availability and the percent of ideal body weight. Dual-energy X-ray absorptiometry was used to obtain total body less head, lumbar spine BMD Z-scores, and lumbar trabecular bone scores (TBS). Pearson’s or Spearman’s correlation coefficients were used to assess the relationship among EA, percent of ideal body weight, and bone parameters. The threshold for statistical significance was set at p < 0.05. The percent of ideal body weight was significantly correlated with the BMD Z-scores of the total body less head (r = 0.61; p < 0.01), lumbar spine (r = 0.55; p < 0.01), and lumbar TBS (r = 0.47; p = 0.03). However, energy availability was not correlated with bone parameters. These findings suggest that screening for low ideal body weight may be a useful predictor of low BMD and insufficient trabecular bone microarchitecture in pubescent female athletes.

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.

In women, fat oxidation during exercise changes with the menstrual cycle. This study aimed to investigate the effect of green tea extract (GTE) ingestion on fat oxidation during exercise depending on the menstrual cycle phase. Ten women with regular menstrual cycles participated in this randomized, double-blind, crossover study. GTE or placebo was administered during the menstrual cycle’s follicular phase (FP) and luteal phase (LP). Participants cycled for 30 min at 50% maximal workload, and a respiratory gas analysis was performed. Serum estradiol, progesterone, free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were assessed before, during, and after the exercise. Fat oxidation, carbohydrate oxidation, and the respiratory exchange ratio (RER) were calculated using respiratory gas. Fat oxidation during the exercise was significantly higher in the FP than in the LP with the placebo (p < 0.05) but did not differ between the phases with GTE. Carbohydrate oxidation, serum-free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were not significantly different between the phases in either trial. Our results suggest that GTE ingestion improves the decrease in fat oxidation in the LP.

The Effect of Co-Ingestion of Carbohydrate with Milk after Exercise in Healthy Women: Study Considering the Menstrual Cycle

Objective: Stress fractures (SF), menstrual dysfunction (MD), and eating disorders (ED) in young athletes are important issues. We conducted this study to determine the frequency of SF, MD, and ED experienced by high school track and field athletes in Japan and to understand the factors associated with them. Materials and Methods: A cross-sectional study of 1199 high level high school track and field athletes (608 males and 591 females) who participated in a selective training camp held by the Japan Association of Athletics Federations. Results: Approximately one in four male and female athletes self-reported SF. Moreover, we identified the length of the practice time per week and the event (sprinting, middle-distance, jumping, and combined) as relevant factors. Approximately one in three female athletes self-reported MD history, with those participating in long-distance events experiencing it significantly more frequently than those participants in sprinting, throwing, and jumping events. Furthermore, we identified ED history and long-distance events as MD history-related factors. ED history was self-reported at low frequency without gender difference, and long-distance was significantly more frequently reported than sprinting and jumping. Conclusions: About a quarter of Japanese high school track and field athletes experience SF, and about a third of the females experience MD. The association of these with athletic events, training time, and ED should be considered.

Despite extensive research on the effects of caffeine intake on fat oxidation during and after aerobic exercise, its effects on women using oral contraceptives (OCs) remain unclear. This study investigated the effects of caffeine intake on fat oxidation during and after aerobic exercise in women using OCs. This study included 13 sedentary women using OCs. The subjects completed three consecutive 10-min bouts of cycling at 40% peak oxygen uptake separated by 10-min rest periods. Each session was conducted 60 min after intake of either caffeinated coffee (CAF; 5 mg/kg) or decaffeinated coffee (CON) in a randomized, double-blind, crossover design. Serum caffeine concentrations were measured before intake, preexercise, immediately postexercise, and 30, 60, and 90 min postexercise. Fat oxidation was measured before intake, preexercise, during exercise (EX1 and EX2), immediately postexercise, and 30, 60, and 90 min postexercise. The serum caffeine concentration in the CAF was significantly higher than that in the CON preexercise, immediately postexercise, and 30, 60, and 90 min postexercise (all p < .001). Fat oxidation in the CAF was significantly lower than that in the CON before intake ( p < .05) but higher than that in the CON immediately postexercise ( p < .05). The change in fat oxidation in the CAF was significantly higher than that in the CON at preexercise, EX1, immediately postexercise, and 30, 60, and 90 min postexercise (all p < .05). This study suggests that caffeine intake before exercise enhances fat oxidation during and after exercise in women taking OCs.