Search Results

You are looking at 1 - 10 of 30 items for :

  • "free testosterone" x
  • All content x
Clear All
Restricted access

Christopher M. Gaviglio, Blair T. Crewther, Liam P. Kilduff, Keith A. Stokes, and Christian J. Cook

Purpose:

To assess the measures of salivary free testosterone and cortisol concentrations across selected rugby union matches according to game outcome.

Methods:

Twenty-two professional male rugby union players were studied across 6 games (3 wins and 3 losses). Hormone samples were taken 40 min before the game and 15 min after. The hormonal data were grouped and compared against competition outcomes. These competition outcomes included wins and losses and a game-ranked performance score (1–6).

Results:

Across the entire team, pregame testosterone concentrations were significantly higher during winning games than losses (P = 5.8 × 10−5). Analysis by playing position further revealed that, for the backs, pregame testosterone concentrations (P = 3.6 × 10−5) and the testosterone-to-cortisol ratio T:C (P = .038) were significantly greater before a win than a loss. Game-ranked performance score correlated to the team’s pregame testosterone concentrations (r = .81, P = .049). In backs, pregame testosterone (r = .91, P = .011) and T:C (r = .81, P = .05) also correlated to game-ranked performance. Analysis of the forwards’ hormone concentrations did not distinguish between game outcomes, nor did it correlate with game-ranked performance. Game venue (home vs away) only affected postgame concentrations of testosterone (P = .018) and cortisol (P = 2.58 × 10−4).

Conclusions:

Monitoring game-day concentrations of salivary free testosterone may help identify competitive readiness in rugby union matches. The link between pregame T:C and rugby players in the back position suggests that monitoring weekly training loads and enhancing recovery modalities between games may also assist with favorable performance and outcome in rugby union matches.

Restricted access

Arny A. Ferrando and Nancy R. Green

The effect of boron supplementation was investigated in 19 male bodybuilders, ages 20–27 years. Ten were given a 2.5-mg boron supplement while 9 were given a placebo every day for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on Days 1 and 49 of the study. Plasma boron values were significantly (p<0.05) different as the experimental group increased from (±SD) 20.1 ±7.7 ppb pretest to 32.6 ±27.6 ppb posttest, while the control group mean decreased from 15.1 ±14.4 ppb pretest to 6.3 ±5.5 ppb posttest. Analysis of variance indicated no significant effect of boron supplementation on any of the dependent variables. Both groups demonstrated significant increases in total testosterone, lean body mass, 1-RM squat, and 1-RM bench press. The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser trained bodybuilders, and that boron supplementation had no effect on these measures.

Restricted access

Alexandre Moreira, Arnaldo Mortatti, Marcelo Aoki, Ademir Arruda, Camila Freitas, and Christopher Carling

This study investigated the contribution of salivary testosterone (sT) concentration, years from peak height velocity (YPHV) and height by body mass interaction on jumping performance (Countermovement jump; CMJ) and aerobic fitness (Yo-Yo intermittent endurance test, level 1) in young elite soccer players. Forty-five participants (age: 12.5 ± 0.5y; body mass: 48.6 ± 10.2kg, height: 155.7 ± 10.0cm) belonging to a top level Brazilian soccer club were evaluated at four time points across a single semester. None of the assessed players had reached PHV. The data from the four evaluations were averaged and multiple linear regression analysis conducted. For CMJ, the model explained 42.88% of the variance (R 2 = 42.88; p < .000); sT concentration was the primary contributor (R 2 = 32.84) and the YPHV contributed 9.95% of the variance. The model explained 28.50% (p < .000) of the variance in Yo-Yo. The sT was the primary and single significant contributor (R 2 = 21.32). A significant difference was noted between high and low testosterone groups divided a posteriori to CMJ performance (t = 3.35; p = .001). These results suggest an important role for hormonal status in interpreting physical performance in preadolescent soccer players.

Restricted access

Michelle S. Rockwell, Madlyn I. Frisard, Janet W. Rankin, Jennifer S. Zabinsky, Ryan P. Mcmillan, Wen You, Kevin P. Davy, and Matthew W. Hulver

beginning the study. Figure 1 —Experimental design. VITD = 5,000 IU of vitamin D 3 ; PTH = parathyroid hormone; fT = free testosterone; tT = total testosterone; SHBG = sex hormone-binding globulin; IGF-1 = insulin-like growth factor 1; DXA = dual-energy X-ray absorptiometry. Participants Male and female

Restricted access

Darryn S. Willoughby, Colin Wilborn, Lemuel Taylor, and William Campbell

This study examined the effects of an aromatase-inhibiting nutritional supplement on serum steroid hormones, body composition, and clinical safety markers. Sixteen eugonadal young men ingested either Novedex XT™ or a placebo daily for 8 wk, followed by a 3-wk washout period. Body composition was assessed and blood and urine samples obtained at weeks 0, 4, 8, and 11. Data were analyzed by 2-way repeated-measures ANOVA. Novedex XT resulted in average increases of 283%, 625%, 566%, and 438% for total testosterone (P = 0.001), free testosterone (P = 0.001), dihydrotestosterone (P = 0.001), and the testosterone:estrogen ratio (P = 0.001), respectively, whereas fat mass decreased 3.5% (P = 0.026) during supplementation. No significant differences were observed in blood and urinary clinical safety markers or for any of the other serum hormones (P > 0.05). This study indicates that Novedex XT significantly increases serum androgen levels and decreases fat mass.

Restricted access

Jussi Kosola, Markku Ahotupa, Heikki Kyröläinen, Matti Santtila, and Tommi Vasankari

Purpose:

We hypothesized that lower androgen status together with poor physical fitness associates with atherogenic lipid profile and oxidative stress.

Methods:

Volunteered young men (N = 846, mean age 25.1 ± 4.6 years) were categorized into unfit, average fit, and fit groups according to tertiles of maximal oxygen uptake, series of muscle endurance tests, and maximal upper and lower body strength. Furthermore, concentrations of serum testosterone (TT) and free testosterone (FT) were determined to divide participants into lower and higher testosterone (loTT, hiTT) and free testosterone (loFT, hiFT) subgroups, using medians as cut-off points. The participants were divided into subgroups according to Fitness × Testosterone (Unfit/Average Fit/Fit × Low/High TT/FT), and the concentrations of serum lipids and ox-LDL were measured. Results: The loTT/unfit cardiorespiratory subgroup had 29% higher concentration of ox-LDL compared with the loTT/fit cardiorespiratory subgroup (p = .044). The loTT / unfit cardiorespiratory subgroup had a significantly higher ratio of ox-LDL/HDL-cholesterol compared with the other five TT subgroups (p < .05, in all). While ox-LDL showed a gradual form of decrease from unfit to fit in loTT cardiorespiratory subgroups, no differences were seen in muscular fitness or maximal strength (upper and lower body) subgroups.

Conclusions:

Young men with poor cardiorespiratory fitness together with lower levels of TT have higher concentrations of ox-LDL. Good cardiorespiratory fitness combined with lower androgen levels is not related to atherogenic lipid profile. The combination of poor muscular fitness, or maximal muscle strength, and lower TT levels does not cause atherogenic lipid profile.

Restricted access

Lauren E. Gyllenhammer, Amanda K. Vanni, Courtney E. Byrd-Williams, Marc Kalan, Leslie Bernstein, and Jaimie N. Davis

Background:

Lifetime physical activity (PA) is associated with decreased breast cancer (BC) risk; reports suggest that PA during adolescence contributes strongly to this relationship. PA lowers production of sex hormones, specifically estradiol, or decreases insulin resistance (IR), thereby lowering risk. Overweight Latina adolescents are insulin resistant and exhibit low levels of PA, potentially increasing their future BC risk.

Methods:

37 obese Latina adolescents (15.7 ± 1.1 yrs) provided measures of PA using accelerometry; plasma follicular phase estradiol, sex-hormone binding globulin, total and free testosterone, dehydroepiandrosterone-sulfate (DHEAS); IR using HOMA-IR; and body composition via DEXA. Partial correlations and stepwise linear regressions assessed cross-sectional relationships between sex hormones, IR and PA. Body composition, and age were included a priori as covariates.

Results:

Estradiol was negatively associated with accelerometer counts per minute (CPM; r = −0.4; P = .02), percent time spent in moderate PA (%MPA; r = −0.5; P = .006), and percent time in moderate or vigorous PA (%MVPA; r = −0.5; P = .007). DHEAS was positively associated with CPM (r = .4, P = .009), %MPA (r = .3, P = .04), and %MVPA (r = .3, P = .04). Other sex hormones and IR were not associated with PA measures.

Conclusion:

This study is the first to show that higher habitual PA was inversely associated with estradiol in obese adolescents.

Restricted access

Bradley C. Nindl, William J. Kraemer, Lincoln A. Gotshalk, James O. Marx, Jeff S. Volek, Jill A. Bush, Keijo Häkkinen, Robert U. Newton, and Steve J. Fleck

Regional fat distribution (RFD) has been associated with metabolic derangements in populations with obesity. For example, upper body fat patterning is associated with higher levels of free testosterone (FT) and lower levels of sex-hormone binding globulin (SHBG). We sought to determine the extent to which this relationship was true in a healthy (i.e., non-obese) female population and whether RFD influenced androgen responses to resistance exercise. This study examined the effects of RFD on total testosterone (TT), FT, and SHBG responses to an acute resistance exercise test (ARET) among 47 women (22 ± 3 years; 165 ± 6 cm; 62 ± 8 kg; 25 ± 5 %BF; 23 ± 3 BMI). RFD was characterized by 3 separate indices: waist-to-hip ratio (WHR), ratio of upper arm fat to mid-thigh fat assessed with magnetic resonance imaging (MRI ratio), and ratio of subscapular to triceps ratio (SB/TRi ratio). Skinfolds were measured for the triceps, chest, subscapular, mid-axillary, suprailaic, abdomen, and thigh regions. The ARET consisted of 6 sets of 10 RM squats separated by 2-min rest periods. Blood was obtained pre- and post- ARET. TT, FT, and SHBG concentrations were determined by radioimmunoassay. Subjects were divided into tertiles from the indices of RFD, and statistical analyses were performed by an ANOVA with repeated measures (RFD and exercise as main effects). Significant (p < .05) increases following the AHRET were observed for TT (~25%), FT (~25%), and SHBG (4%). With multiple regression analysis, anthropometric measures significantly predicted pre- concentrations of FT, post-concentrations of TT, and pre-concentrations of SHBG. The SB/TRi and MRI ratios but not the WHR, were discriminant for hormonal concentrations among the tertiles. In young, healthy women, resistance exercise can induce transient increases in testosterone, and anthropometric markers of adiposity correlate with testosterone concentrations.

Restricted access

Review Article Stroke Volume Dynamics During Progressive Exercise in Healthy Adolescents Thomas Rowland * Viswanath Unnithan * 5 2013 25 2 173 185 10.1123/pes.25.2.173 Original Research Role of Free Testosterone in Interpreting Physical Performance in Elite Young Brazilian Soccer Players

Restricted access

-Arrones * Carlos Arenas * Guillermo López * Bernardo Requena * Oliver Terrill * Alberto Mendez-Villanueva * 3 2014 9 2 316 323 10.1123/ijspp.2013-0069 Relationship Between Pregame Concentrations of Free Testosterone and Outcome in Rugby Union Christopher M. Gaviglio * Blair T. Crewther * Liam P