Influence Of Sexual Maturation Research Articles

Influence of sexual maturation on anaerobic performance of male adolescent wrestlers

This study aimed to examine the impact of sexual maturation on the anaerobic performance of male adolescent wrestlers. Methods: We included a sample of 29 freestyle and Greco-Roman wrestlers from various clubs in Barinas, Venezuela. Their physical characteristics were as follows (mean ± SD): age, 14.99 ± 1.83 years; body mass, 54.68 ± 16.80 kg; height, 161.06 ± 12.78 cm; body fat, 12.09 ± 4.11%; body mass index (BMI), 20.58 ± 3.79 kg/m2; and training experience, 3.66 ± 2.27 years. Sexual maturation was evaluated using Tanner's criteria, while anaerobic performance was assessed with the 30-second Wingate test for both lower and upper body. Results: There were moderate to strong significant correlations between maturation development and both peak power (PP) and average power (AP) — for both absolute and relative measures — for the lower and upper body. The fatigue index (%FI) for the lower body did not show any correlation with maturation development or with the pubescent and postpubescent maturation categories. Conversely, the %FI for the upper body demonstrated a significant moderate correlation with maturation development and with the postpubescent maturation category. Additionally, a strong significant correlation was observed between the pubescent maturation category and both PP and AP (absolute and relative) for the lower body. A moderate correlation was found between the postpubescent category and PP (absolute) for the upper body. PP (absolute) and AP (relative) for the upper body had a moderate correlation with the pubescent maturation category, while the postpubescent category showed a strong correlation with PP (absolute), AP (absolute), and AP (relative). Conclusion: The stages of sexual maturation significantly influence the anaerobic capacity of adolescent wrestlers, potentially affecting their training adaptations for peak performance. Future research should explore the physiological responses to training protocols tailored to specific stages of maturation.

The volatile compound profile in the meat of chickens raised in a free-range system varies with sexual maturity

This study aimed to characterize and evaluate the profile of volatile compounds found in the meat of chickens raised in a free-range system as a function of their sex and sexual maturity. A completely randomized design (CRD) was used, and 90 birds were categorized as immature males, mature males, immature females or mature females. Samples of breast and drumstick cuts were analyzed. The volatile compounds were extracted by solid-phase microextraction (SPME), and the compounds were identified by mass spectrometry and the Kovats index. Ninety-six volatile compounds were identified. Aldehydes, terpenes, and alcohols composed the highest numbers of identified volatile compounds. There was a stronger relationship between aldehyde, ketone, terpene, furan and sulfur compounds with drumstick meat from mature males compared with the other samples. Ester compounds were more strongly associated with chicken meat from immature females in breast cut. In breast meat, the alcohol group was negatively correlated with immature chickens in both sexes and increased with sexual maturity. Compounds such as aldehydes, hydrocarbons, carboxylic acids, and pyrazines were more strongly related to the breast meat of mature females. There was a difference in the profile of volatile compounds between mature and immature chickens according to sex and cut. Male and female chickens demonstrated compounds that could change the taste of chicken meat, indicating that the influence of sexual maturity was a common factor.

The influence of sexual maturity on the meat quality of free-range chickens

This research study aimed to evaluate the influence of sexual maturity on meat quality parameters in chickens raised in a free-range system. The fully randomized design (FRD) used a (2x2) factorial scheme, with two sexes (male and female) and two categories of sexual maturity (immature and mature). Ninety birds (45 females and 45 males) belonging to the Label Rouge (Pescoço Pelado) strain were slaughtered at five different ages (70, 90, 120, 150, and 180 days). The physicochemical parameters, centesimal composition and shelf life of the meat were assessed. In both breast and leg cuts, sexual maturity promoted an increase in shear force and affected the meat color by increasing its redness (a*). Moisture was higher in leg meat after sexual maturity. In both breast and leg cuts, ether extract was higher in sexually mature females. Sexual maturity also caused a decrease in tenderness and shorter shelf life of the meat.

228 Shifts in the skin bacteria and fungi in healthy children transitioning through puberty

While skin microbial shifts among different age groups are known from several culture- and sequencing-based studies, the influence of sexual maturation on the skin microbiome in individuals followed longitudinally has not been studied as systematically. In this prospective and longitudinal study, twelve healthy children were evaluated up to 6 years to investigate puberty-associated skin microbial shifts. Using 16S rRNA (V1-V3) and ITS1 amplicon sequencing with DADA2 analysis, bacterial and fungal communities of five different skin sites were analyzed and compared with serum hormone levels. The composition and the diversity of skin microbial communities transitioned toward a more ‘adultlike’ microbiome. The microbial shifts were associated with Tanner stages and showed sex-specific differences. Female children demonstrated increasingly predominant lipophilic Cutibacterium and Malassezia in early Tanner (2-3) versus late Tanner (4-5) stages (mean relative abundances of Cutibacterium, P < 0.001 [15.9% to 32.2%] for antecubital fossa; Malassezia, P = 0.03 [28.6% to 53.3%] for antecubital fossa and P < 0.001 [24.5% to 58.5%] for volar forearm). Furthermore, the microbial communities in female children converged to be more similar to one another with increasing Tanner stages, but not in male children. The higher relative abundances of lipophilic species, C. acnes and M. restricta, were strongly associated with levels of serum androgens which are known to influence sebaceous gland activity (testosterone, P < 0.001 for C. acnes and M. restricta; androstenedione, P = 0.11 for C. acnes and P = 0.16 for M. restricta), suggesting hormonal effects on the skin microbial communities. In summary, these results signify complex interrelationships of sexual maturation, skin microbiome, and skin physiology.

355 Shifts in the skin bacterial and fungal microbiomes of healthy children transitioning through puberty

Previous cross-sectional studies have shown that skin microbiomes of adults and older children are distinct from those of younger children. However, the influence of sexual maturation on the human skin microbiome in individuals followed over time has not been studied as extensively. We performed a prospective, longitudinal study to investigate puberty-dependent shifts in skin microbiota. Twelve healthy children (4 girls and 8 boys) were evaluated every 6-18 months for up to 6 years at the outpatient dermatology clinic in the National Institute of Health Clinical Center.

Could α1-adrenoceptors and androgen receptors be modified by sexual maturation and testosterone in the rat testicular capsule?

Testicular capsule contractile dysfunctions are recognized to contribute to male infertility, but the influence of sexual maturation and exogenous testosterone on the expression and function of androgen receptor and α1-adrenoceptors on rat testicular capsule is unclear. Here, these two biological parameters were evaluated on testicular capsule from sexually immature and young adult rats treated or not with exogenous testosterone. Male Wistar rats (45- and 60-day-old) were assigned into groups: control (saline 0.9%) or testosterone-treated (propionate testosterone). Testicular capsule was isolated and processed for functional studies, immunohistochemistry, Western blot and RT-PCR studies. Relative testicular capsule wet weight was not affected by sexual maturation or exogenous testosterone treatment. The expression and immunolocalization of androgen receptor (mRNA and protein) was identified in testicular capsule. Androgen receptor and α1-adrenoceptor (Adra1a, Adra1b, and Adra1d) mRNA levels were similar in testicular capsule from all experimental groups. Functional studies indicated that contractions produced by noradrenaline in testicular capsule from 45- and 60-day-old rats treated or not with testosterone were mainly mediated by α1A- and α1B-adrenoceptors. The L-type Ca(2+) channel blocker nifedipine induced a higher inhibitory effect on noradrenaline induced contractions in testicular capsule from 45- than 60-day-old rats treated with testosterone. Molecular studies, immunohistochemistry and pharmacological functional assays used in this study provide evidences of the androgen receptor expression in testicular capsule and that function, and not mRNA and protein expression levels of the α1-adrenoceptor subtypes in this tissue, is differentially influenced by the rat androgen status.

Influência da maturação sexual na aptidão cardiorrespiratória em escolares

Levels of aerobic fitness of children and adolescents are declining worldwide, which results in increased health risks. In Brazil, approximately 60% of the students present levels of fitness lower than recommended for age and sex. Our objective was to determine the influence of sexual maturation and physical activity level on cardiorespiratory fitness of schoolchildren of both sexes aged 9-14 years. This was a cross-sectional including a sample of 747 individuals (47.12% female) aged 9 to 14 years enrolled in public schools. The participants completed the Physical Activity Questionnaire for Children (PAQ-C) and a questionnaire on sexual maturation, and performed the shuttle run test. In order to verify the influence of sexual maturation on VO2max, students were categorized according to maturation stage (prepubertal, pubertal and postpubertal), sex, and interaction between sex and maturation. ANOVA was used to compare mean maturation stages and to assess whether sex and maturation affect VO2max. There was influence of maturation (p &lt;0.0001; Eta2= 0.069, power = 1) and sex (p &lt;0.0001; Eta2= 0.059, power = 1) on aerobic fitness. VO2maxvalues were different between the maturation stages in both sexes, and between sexes at the same maturation stage. Maturation influenced VO2maxwith a decreasing linear trend (p &lt;0.0001; Eta2= 0.221, power = 1) for females. An influence of maturation and physical activity level on cardiorespiratory fitness was observed in schoolchildren of Aracaju city.

Maturity‐associated variation in total and depot‐specific body fat in children and adolescents

This study considered the association between sexual maturation and adiposity in children and adolescents, and examined the contribution of sexual maturation to ethnic differences in total and depot-specific body fat. The sample included 382 White and African American 5-18-year-olds. Body mass index (BMI), waist circumference (WC) and sexual maturity status (breast/genital and pubic hair stage) were assessed in a clinical setting. Total body fat (TBF) was measured by dual-energy X-ray absorptiometry and abdominal subcutaneous (SAT) and visceral adipose tissue (VAT) were measured by magnetic resonance imaging. Analysis of covariance adjusted for age was used to examine the association between sexual maturity status and adiposity, and linear regression adjusted for age was used to examine the influence of sexual maturation on ethnic differences in adiposity. Analysis of VAT also controlled for TBF. Significance was accepted at P < 0.05. Breast/genital stage was significantly associated with BMI, WC, TBF, and SAT in girls of both ethnic groups and in White boys. Breast stage was associated with VAT. Stage of pubic hair was significantly associated with TBF and VAT in White girls only. In girls, sexual maturation attenuated the ethnic effects on BMI and WC, but the ethnic effect in VAT persisted. In boys, sexual maturation did not attenuate ethnic differences on VAT and did not predict WC or SAT. Sexual maturity status independently explained variance in adiposity in girls only. Sexual maturity status is an important determinant of pediatric adiposity and attenuates ethnic differences in girls' adiposity.

P2-55 Influence of sexual maturation on body mass index in a longitudinal study with adolescents from Brazil

IntroductionBody mass index (BMI) during adolescence is highly influenced by the pubertal maturation, and early maturation has been associated with overweight, but it is still uncertain if these factors are...

GENDER AND RURAL–URBAN DIFFERENCES IN THE NUTRITIONAL STATUS OF IN-SCHOOL ADOLESCENTS IN SOUTH-WESTERN NIGERIA

This study assessed gender and rural/urban differences in height and weight, and the prevalence of stunting, underweight and overweight of school-going adolescents in south-west Nigeria, using 2007 WHO reference values for comparison. The influence of sexual maturity and the socio-demographic correlates of growth performance were also examined. In this cross-sectional study, 924 male (51.4%) and 875 female (48.6%) students (1799 in total) aged 10-19 years from eighteen schools in Ibadan (five rural, nine urban public and four urban private) were interviewed and examined. Although males were significantly taller than females (p<0.05), stunting was more pronounced for males, who were 7.5 cm shorter than the 2007 WHO reference, compared with females who were 3.5 cm shorter. Body mass index (BMI) for girls was also greater than for boys (p<0.05). Rural adolescents had lower heights and BMIs compared with those in urban areas. The mean height of male adolescents in rural schools fell below 2 SDs of the 2007 WHO reference between 14 and 17 years, while heights of males and females in private schools were similar to the median 2007 WHO standard. Low height-for-age was observed in 282 adolescents (15.7%), which, after multivariate analysis, was significantly associated with school type, gender, number of mother's children and puberty onset. Adolescents in rural schools were much more likely to be stunted than those in urban private schools (AOR 13.1; 95% CI 5.2-33.2) and males were three times more likely to be stunted compared with females (AOR 3.3; 95% CI 2.4-1.4). Low BMI-for-age was observed in 240 adolescents (18.9%), with correlates similar to stunting. Adolescents at the pre-puberty stage were twice as likely to have low BMI-for-age (OR 2.0; 95% CI 1.6-2.5) than those with signs of puberty. There were 2.3% overweight adolescents, who were significantly more likely to be female, in private school and post-pubertal. Innovative interventions for Nigerian adolescents, especially rural inhabitants and males, are needed to reduce the prevalence of stunting and underweight.

NAMPT (visfatin) in the chicken testis: influence of sexual maturation on cellular localization, plasma levels and gene and protein expression

Nicotinamide phosphoribosyltransferase (NAMPT) is a cytokine hormone and rate-limiting enzyme involved in production of NAD and therefore affects a variety of cellular functions requiring NAD. Spermatogenesis and testicular steroidogenesis are likely to depend on NAD-dependent reactions and may therefore be affected by changes in testicular NAMPT expression. The objectives of the present study are to investigate testicular NAMPT expression as well as plasma NAMPT levels in prepubertal and adult chickens. By RT-PCR, NAMPT cDNA expression was detected in prepubertal and adult chicken testes. Using immunohistochemistry, NAMPT was predominantly localized in the nucleus of myoid cells, Sertoli cells, and Leydig cells in the prepubertal chicken testis. In adult chickens, however, NAMPT-immunostaining was observed in the cytoplasm of Leydig cells, Sertoli cells, primary spermatocytes, secondary spermatocytes, round spermatids, and elongated spermatids, but not in the spermatogonial cells. Using real-time quantitative PCR, adult chicken testis was found to contain fourfold greater NAMPT mRNA quantity compared with prepubertal chickens. Testicular NAMPT protein quantities determined by western blotting were not significantly different between adult and prepubertal chicken testes. Using immunoblotting, NAMPT was detected in the seminal plasma and sperm protein extracts obtained from chicken semen. Plasma NAMPT levels, determined by enzyme immunoassay, were at least 28-fold higher in the adult chickens compared with prepubertal male chickens. Taken together, sexual maturation is associated with several changes in testicular NAMPT expression indicating that NAMPT is likely to play a significant role in testicular functions such as spermatogenesis and steroidogenesis.

The influence of sexual maturation on blood pressure and body fatness in African‐American adolescent girls and boys

To examine the influence of sexual maturation (SM) on blood pressure (BP) and body fatness during puberty among African-American children. Longitudinal data were collected from 283 African-American children aged 9-15 years over a 1.5-year period. Measured anthropometric measures included height, weight, skinfold thickness, waist circumference (WC), and systolic and diastolic BP (SBP/DBP) at baseline, 1-year, and 1.5-year follow-up were used. SM was assessed using self-reported Tanner stages (range 1-5) at baseline. Spearman correlation and regression analyses were conducted to test associations between study variables. Early maturing girls had higher BP and body mass index (BMI = weight (kg)/height (m)(2)) at follow-up than nonearly maturing girls (SBP: 117.4 vs. 111.7; DBP: 66.3 vs. 60.7; BMI: 27.7 vs. 23.5; all P < 0.05, respectively). Baseline Tanner stage was positively associated with follow-up SBP (r = 0.28), DBP (r = 0.37), BMI (r = 0.45), skinfold thickness (r = 0.37), and WC (r = 0.40) in girls, but not in boys. The influence of SM on BP independent of body size was tested via several different multiple linear regression models by adding measures of body size and their changes (height and BMI) between baseline and follow-up. Early maturing girls had higher SBP and DBP (beta = 4.30, P < 0.05; beta = 3.28, P < 0.05; respectively) and BMI (beta = 1.69, P < 0.05) at 1.5-year follow-up than their counterparts. In boys, a marginally significant reverse association (beta = -1.05 to -1.19) between SM stages and DBP was detected. SM affects BP and body fatness in girls, and should be considered in assessment of BP and obesity in adolescents.

Gonadotrophin‐Inhibitory Hormone Receptor Expression in the Chicken Pituitary Gland: Potential Influence of Sexual Maturation and Ovarian Steroids

Gonadotrophin-inhibitory hormone (GnIH), a hypothalamic RFamide, has been found to inhibit gonadotrophin secretion from the anterior pituitary gland originally in birds and, subsequently, in mammalian species. The gene encoding a transmembrane receptor for GnIH (GnIHR) was recently identified in the brain, pituitary gland and gonads of song bird, chicken and Japanese quail. The objectives of the present study are to characterise the expression of GnIHR mRNA and protein in the chicken pituitary gland, and to determine whether sexual maturation and gonadal steroids influence pituitary GnIHR mRNA abundance. GnIHR mRNA quantity was found to be significantly higher in diencephalon compared to either anterior pituitary gland or ovaries. GnIHR mRNA quantity was significantly higher in the pituitaries of sexually immature chickens relative to sexually mature chickens. Oestradiol or a combination of oestradiol and progesterone treatment caused a significant decrease in pituitary GnIHR mRNA quantity relative to vehicle controls. GnIHR-immunoreactive (ir) cells were identified in the chicken pituitary gland cephalic and caudal lobes. Furthermore, GnIHR-ir cells were found to be colocalised with luteinising hormone (LH)beta mRNA-, or follicle-stimulating hormone (FSH)beta mRNA-containing cells. GnIH treatment significantly decreased LH release from anterior pituitary gland slices collected from sexually immature, but not from sexually mature chickens. Taken together, GnIHR gene expression is possibly down regulated in response to a surge in circulating oestradiol and progesterone levels as the chicken undergoes sexual maturation to allow gonadotrophin secretion. Furthermore, GnIHR protein expressed in FSHbeta or LHbeta mRNA-containing cells is likely to mediate the inhibitory effect of GnIH on LH and FSH secretion.

Adiponectin and its receptors are expressed in the chicken testis: influence of sexual maturation on testicular ADIPOR1 and ADIPOR2 mRNA abundance

Adiponectin is an adipokine hormone that influences glucose utilization, insulin sensitivity, and energy homeostasis by signaling through two distinct receptors, ADIPOR1 and ADIPOR2. While adipose tissue is the primary site of adiponectin expression in the chicken, we previously reported that adiponectin and its receptors are expressed in several other tissues. The objectives of the present study are to characterize adiponectin, ADIPOR1, and ADIPOR2 expressions in the chicken testis and to determine whether sexual maturation affects the abundance of testicular adiponectin, ADIPOR1, and ADIPOR2 mRNAs. By RT-PCR and nucleotide sequencing, testicular adiponectin, ADIPOR1, and ADIPOR2 mRNAs were found to be identical to that expressed in the abdominal fat pad. Using anti-chicken adiponectin, ADIPOR1, or ADIPOR2 antibodies and immunohistochemistry, adiponectin-immunoreactive (ir) and ADIPOR1-ir cells were found exclusively in the peritubular cells as well as in Leydig cells. However, ADIPOR2-ir cells were found in the adluminal and luminal compartments of the seminiferous tubules as well as in interstitial cells. In particular, Sertoli cell syncytia, round spermatids, elongating spermatids, spermatozoa, and Leydig cells showed strong ADIPOR2 immunoreactivity. Using quantitative real-time PCR analyses, testicular ADIPOR1 and ADIPOR2 mRNA abundance were found to be 8.3- and 9-fold higher (P<0.01) in adult chickens compared with prepubertal chickens respectively, suggesting that sexual maturation is likely to be associated with an up-regulation of testicular ADIPOR1 and ADIPOR2 gene expressions. Collectively, our results indicate that adiponectin and its receptors are expressed in the chicken testis, where they are likely to influence steroidogenesis, spermatogenesis, Sertoli cell function as well as spermatozoa motility.

Estudo do perfil lipídico em crianças e jovens do ambulatório pediátrico do Hospital Universitário Antônio Pedro associado ao risco de dislipidemias

Atherosclerotic plaques form early in childhood and progress slowly until adult life, when clinical manifestations show. The goal of this study was to analyze the concentrations in plasma of total cholesterol, LDL-cholesterol (LDL-C), triglycerides (TG) and HDL-cholesterol (HDL-C) in a group of children of both sexes and up to 19 years of age, who are attending at the University Hospital Antonio Pedro (HUAP). Patient admission sheets between December 2004 and January 2006 were analyzed for dyslipidemic risk factors, and correlated with the respective lipid plasma concentrations, determined at the Laboratory of Clinical Chemistry (HUAP). The plasma levels of total cholesterol, LDL-C, TG and HDL-C in female patients were higher than in male patients, suggesting the influence of sexual maturation as described in the literature. The mean concentrations of total cholesterol, LDL-C, TG and HDL-C were elevated in the investigated group, mainly in patients presenting with other pathologies, such as nephrotic syndromes, diabetes mellitus and systemic lupus erythematosus. Our results suggest that, in Brazil, the reference value interval of lipoprotein levels should be investigated more thoroughly in this age group, as well as in children who are considered healthy.

Influência da maturação sexual, idade cronológica e índices de crescimento no limiar de lactato e no desempenho da corrida de 20 minutos

Crianças e adolescentes apresentam, em uma determinada carga, menores concentrações de lactato [la] do que os adultos; especula-se que essas diferenças são ligadas a aspectos maturacionais. O objetivo deste estudo foi verificar a influência da maturação sexual, idade cronológica (I) e índices de crescimento (IC - massa corporal, estatura e somatório de dobras cutâneas subescapular e tricipital) na velocidade do limiar de lactato na concentração fixa de lactato ([la]) de 2,5mmol.l-1 (V2,5) e na corrida de 20 minutos (V20). Trinta e três meninos participantes de escolas de esportes foram submetidos a: 1) avaliação antropométrica e avaliação da maturação sexual através dos índices de Tanner (maturação sexual de órgãos genitais e maturação sexual de pêlos púbicos); 2) teste progressivo descontínuo de 3 x 800m (pista de atletismo) para determinar V2,5; e 3) corrida de 20 minutos para determinar a V20 e a [la] final. Não foi encontrada associação entre maturação sexual, idade cronológica e indicadores de crescimento com V2,5. Somente a estatura se mostrou associada com V20. Assim, outras variáveis de desempenho, fisiológicas ou biomecânicas, podem influenciar mais no limiar de lactato e na corrida de 20 minutos, do que as variáveis de crescimento durante a adolescência.

Influence of sexual maturity on feeding, growth and energy stores of wild Atlantic salmon parr

Maturing Salmo salar parr had significantly lower short-term energy stores (indicated by hepato-somatic index) in August, and significantly lower energy stores and growth rate (indicated by RNA : DNA) in September than immature parr captured from the same stream sites on the same date. There were no significant differences in gut fullness or protein concentrations, suggesting that up to early September the main energetic consequences of maturation were a reduction in allocations to growth and short-term energy storage, but not a mobilization of long-term stored energy in the form of proteins. These are the first observations of relative food intake and energy storage for maturing parr under natural conditions, and also the first to assess growth effects on wild fish before completion of the maturation process.

Influence of sexual maturity on feeding, growth and energy stores of wild Atlantic salmon parr

Influence of sexual maturity on feeding, growth and energy stores of wild Atlantic salmon parr

Pheromones Elicit Equivalent Levels of Fos-Immunoreactivity in Prepubertal and Adult Male Syrian Hamsters

Male reproductive behavior in the Syrian hamster is dependent on both pheromones from the female and the presence of gonadal steroid hormones. The pheromones are contained within female hamster vaginal secretions (FHVS) and stimulate anogenital investigation and mounting by the male. Administration of testosterone to castrated male hamsters facilitates anogenital investigation, mounts, and intromissions in adults, but elicits only anogenital investigation in prepubertal males. One hypothesis for why the full complement of reproductive behaviors is not activated by testosterone in prepubertal males is that the neural processing of pheromonal cues encountered during anogenital investigation is different in juveniles and adults. In the present experiment, we investigated the influence of sexual maturity on Fos expression in response to FHVS in the male Syrian hamster. We predicted a greater increase in Fos-immunoreactivity after exposure to FHVS within the neural circuit mediating male reproductive behaviors in adult compared to prepubertal males. Intact adult and prepubertal males were exposed to either a clean cotton swab or a swab containing FHVS. We found that, compared to animals exposed to a clean cotton swab, both prepubertal and adult males exposed to FHVS have a greater amount of Fos-immunoreactivity within several brain nuclei comprising the neural circuit mediating male reproductive behavior. Furthermore, this Fos response was equivalent in the two age groups. These results suggest that the inability of the prepubertal male hamster to perform the full repertoire of male reproductive behaviors is not due to a lack of a neuronal activation in response to the pheromonal cues present in FHVS.

Performance on the Wingate Anaerobic Test and Maturation

The influence of sexual maturation on the Wingate anaerobic test performance of 100 boys and 100 girls, ages 12.2 ±0.4 years, was examined using Tanner’s indices of pubic hair and, in boys, salivary testosterone as measures of maturation. No sex differences (p &gt; .05) in either peak power (PP) or mean power (MP) were revealed. Significant main effects (p &lt; .01) for maturation were detected for both PP and MP expressed in W, W · kg−1, or with body mass controlled using allometric principles. Testosterone did not increase the variance in PP or MP explained by body mass alone (p &gt; .05). No sex or maturational effects were observed for postexercise blood lactate (p &gt; .05). Testosterone was not (p &gt; .05) correlated with blood lactate. Thus, sexual maturation exerts an influence on PP and MP independent of body mass, but maturational effects on postexercise blood lactate remain to be proven in this age group.