Search

This study investigated the effect of oral contraceptive (OC) use on acute changes in steroid hormone concentrations and tryptophan (TRP) metabolites in response to strength exercise. Twenty-one women (age: 23 ± 3 years), 8 combined OC users (OC group) and 13 naturally cycling women (menstrual cycle [MC] group), participated. Testing was performed during the pill-free interval for the OC group and the follicular phase for the MC group. Subjects completed an intense strength exercise protocol (4 x 10 repetitions back squat). Blood samples were taken at baseline (T0), post-exercise (T1), and after 24 hours (T2) to determine serum concentrations of cortisol, estradiol, testosterone, TRP, and kynurenine (KYN). Statistical significance was defined asp <0.05. At T0, the OC group showed higher cortisol (OC: 493.7 ± 47.1 ng⋅ml-1, MC: 299.1 ± 62.7 ng⋅ml-1, p < 0.001) and blood lactate(OC: 1.81 ±0.61 mmol⋅L-1, MC: 1.06 ± 0.30 mmol⋅L-1, p = 0.001) and lower estradiol (OC: 31.12 ± 4.24 pg⋅mL-1, MC: 38.34 ± 7.50 pg⋅mL-1, p = 0.023) and KYN (OC: 1.15 ± 0.23 μmol⋅L-1, MC: 1.75 ± 0.50 μmol⋅L-1, p = 0.005). No significant interactions (group x time, p> 0.05) were found for the hormones and TRP metabolites assessed. Oral contraceptive use did not affect the physiological response of steroid hormones and TRP metabolites to acute strength exercise during the low hormone phase of the contraceptive or MC in healthy young women, even when some baseline concentrations differed between groups. Consequently, these findings provide important implications for practitioners testing heterogeneous groups of female athletes. [ABSTRACT FROM AUTHOR]

Mooses, M, Haile, DW, Ojiambo, R, Sang, M, Mooses, K, Lane, AR, and Hackney, AC. Shorter ground contact time and better running economy: evidence from female Kenyan runners. J Strength Cond Res 35(2): 481-486, 2021-Previously, it has been concluded that the improvement in running economy (RE) might be considered as a key to the continued improvement in performance when no further increase in V̇o2max is observed. To date, RE has been extensively studied among male East African distance runners. By contrast, there is a paucity of data on the RE of female East African runners. A total of 10 female Kenyan runners performed 3 × 1,600-m steady-state run trials on a flat outdoor clay track (400-m lap) at the intensities that corresponded to their everyday training intensities for easy, moderate, and fast running. Running economy together with gait characteristics was determined. Subjects showed moderate to very good RE at the first (202 ± 26 ml·kg-1·km-1) and second (188 ± 12 ml·kg-1·km-1) run trials, respectively. Correlation analysis revealed significant relationship between ground contact time (GCT) and RE at the second run (r = 0.782; p = 0.022), which represented the intensity of anaerobic threshold. This study is the first to report the RE and gait characteristics of East African female athletes measured under everyday training settings. We provided the evidence that GCT is associated with the superior RE of the female Kenyan runners. [ABSTRACT FROM AUTHOR]

Myllyaho, MM, Ihalainen, JK, Hackney, AC, Valtonen, M, Nummela, A, Vaara, E, Häkkinen, K, Kyröläinen, H, and Taipale, RS. Hormonal contraceptive use does not affect strength, endurance, or body composition adaptations to combined strength and endurance training in women. J Strength Cond Res 35(2): 449-457, 2021-This study examined the effects of a 10-week period of high-intensity combined strength and endurance training on strength, endurance, body composition, and serum hormone concentrations in physically active women using hormonal contraceptives (HCs, n = 9) compared with those who had never used hormonal contraceptives (NHCs, n = 9). Training consisted of 2 strength training sessions and 2 high-intensity running interval sessions per week. Maximal bilateral isometric leg press (Isom), maximal bilateral dynamic leg press (one repetition maximum [1RM]), countermovement jump (CMJ), a 3,000-m running test (3,000 m), body composition, and serum hormone levels were measured before and after training between days 1-5 of each subject's menstrual cycle. Both groups increased 1RM and CMJ: HC = 13.2% (p < 0.001) and 9.6% (p < 0.05), and NHC = 8.3% (p < 0.01) and 8.5% (p < 0.001). Hormonal contraceptive improved 3,000 m by 3.5% (p < 0.05) and NHC by 1% (n.s.). Never used hormonal contraceptive increased lean mass by 2.1% (p < 0.001), whereas body fat percentage decreased from 23.9 ± 6.7 to 22.4 ± 6.0 (-6.0%, p < 0.05). No significant changes were observed in body composition in HC. No significant between-group differences were observed in any of the performance variables. Luteinizing hormone concentrations decreased significantly (p < 0.05) over 10 weeks in NHC, whereas other hormone levels remained statistically unaltered in both groups. It seems that the present training is equally appropriate for improving strength, endurance, and body composition in women using HC as those not using HC without disrupting hypothalamic-pituitary-gonadal axis function. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of 2 soccer-training seasons on physical fitness and hormone concentrations in elite youth soccer players. Twenty male elite soccer players (SP, age 14.5 ± 0.4 years) and 20 male control subjects (CS, age 14.3 ± 0.3 years) participated in the study. Anthropometric measurements, aerobic (Yo-Yo Intermittent Recovery Test Level 1 [YYIRT1]) and anaerobic soccer relevant performances (jump and sprint tests), blood testosterone (T), cortisol (C), sex hormone binding globulin (SHBG), and T/C ratio were assessed 5 times (from T0 to T4) during 2 competitive seasons. Significant differences from basal values (Δ) of T, SHBG, and C between SP and CS were observed (p < 0.01). Additionally, T and T/C ratio changes were positively correlated with physical performance (p ≤ 0.05). In conclusion, as expected, higher T concentration and greater power performance were observed in the soccer players group compared with controls. Our findings also show that the T concentrations and power performance outcomes co-vary positively over the 2 soccer seasons in soccer players. [ABSTRACT FROM AUTHOR]