Well I thought I’d start a thread about testosterone. I’ll post some studies for food for thought.
Effect of androgens on histochemical fibre type
The temporal muscles of the guinea pig show a sexual differentiation reflected in their histochemical enzyme pattern. Using histochemical methods for mitochondrial (SDH, agr-GPDH), and glycolytic enzymes (phosphorylase, LDH) it could be shown, that in adult animals the ‘‘male’’ muscle is a ‘‘white’’ muscle with marked activity of glycolytic enzymes, the ‘‘female’’ muscle a ‘‘red’’ muscle displaying high activity of mitochondrial enzymes. This differential enzyme pattern can be converted by the application of testosterone to the female type during the postnatal development. The male sex hormone thus affects the histochemical enzyme pattern of the muscle, converting the ‘‘red’’, ‘‘female’’ into a ‘‘white’’,’‘male’’ muscle in the female guinea pig.
Testosterone to Cortisol Ratio Shows Strong Relationship With Adaptation to a Strength and Power Training Regimen in American-style Collegiate Football Players
PURPOSE: Previous research has demonstrated strong correlation between hormonal markers and physical performance. The purpose of this study was to examine the relationship that hormonal markers shared with performance measures and to establish whether or not alterations in performance were reflected through shifts in hormone profile.
METHODS: Twenty-two freshman collegiate American-style football players were recruited this study (Age = 18.41 ± 0.73 years; Mass = 107.60 ± 22.97 kg; and Height 188.31 ± 6.71 cm). Ten collegiate males were recruited as an experimental control (Age = 19.01 ± 0.81 years; Mass = 91.45 ± 17.12 kg; and Height = 168.94 ± 7.12 cm). Performance testing included peak isometric force (PF), rate of force development (RFD), broad jump (BJ), and vertical jump (VJ). Hormone values included free testosterone (T), cortisol ©, and testosterone to cortisol ratio (T/C), measured via enzyme-linked immune assay. Following initial testing, treatment group subjects participated in seven weeks of strength and power training. Control group subjects were instructed not to participate in strength or power training during the course of the study. Statistical analysis was performed using a Pearson product-moment correlation and reliability was determined via interclass correlation (ICC). A paired t-test was used to compare pre-post means between the performance variables of PF and RFD within groups. An additional paired t-test was performed examining pre-post means of the BJ and VJ tests. A final paired t-test was performed to compare the pre-post means of the hormonal markers T, C, and T/C. The level of significance was set at p <.05, and was adjusted to cover for multiple comparisons using a Bonferroni adjustment.
RESULTS: Significant correlations were observed between pre T/C and percent improvements in performance variables pre-post (BJ = 3.8% r = 0.59, PF = 16.8% r = 0.62, RFD = 20.1% r = 0.67, VJ = 4.1% r = 0.64).
CONCLUSIONS: The results of this study suggest that the hormonal markers T, C, and T/C share significant correlation with indices of strength and power performance and that these relationships are sensitive to alterations in strength and power performance capabilities. Practitioners wishing to monitor training and adaptation may wish to consider the use of such hormonal markers in their participants.
Hormonal Markers And Physical Performance During A Peak-taper Cycle In Elite Track And Field Athletes
PURPOSE: To investigate the relationship between physical performance and testosterone and cortisol following short term alterations in training volume and intensity.
METHODS: Five male qualifiers for the 2006 NCAA D-I national track and field meet took part. At study start, they had just finished a peaking training phase prior to competition in a NCAA regional meet. Peaking involved a 2 week elevation in training volume/intensity, followed by 1 week reduction in training volume/intensity prior to the regional and national meets. Testing occurred immediately prior to beginning the peaking phase (pre), to the onset of the taper cycle (mid), and to leaving for the national meet (post). For each athlete, all tests were performed at the same time of day, on the same day of the week, and with a minimum of 48 h prior rest. The performances tested were broad jump (BJ) and mid-thigh pull. Testosterone (T) and cortisol © were determined from saliva samples. Samples were analyzed in duplicate via ELISA.
RESULTS: Free T (nmol/L) went unchanged throughout the study (pre= 9.7 ± 1.5, mid=9.6 ± 1.2, post=10.8 ± 1.6, mean±std. dev). On the other hand, free C (nmol/L) rose significantly (p<0.05) at mid, but returned to pre levels at post (pre=18.5 ± 3.7, mid=22.2 ± 3.7, post=15.8 ± 2.3). T/C ratio was also increased at mid but returned to pre at post (pre=.5 ±.3, mid=.4 ±.1, post=.7 ±.2). Additionally, significant correlations were observed between T and BJ, peak force (PF), and rate of force development (RFD) for pre (r =.54,.42,.59), mid (r =.44,.62,.57), and with BJ and RFD during post (r =.56,.53). Significant negative correlations were observed between C and BJ and RFD during pre (r = -.44, -.47), and with RFD during mid (r = -.51), and post (r = -.50). Significant correlations were observed between T/C and BJ and RFD during pre (r =.64,.68), with PF during mid (r =.64), and with BJ, PF, and RFD during post (r =.68,.71,.74).
CONCLUSIONS: Athletes increasing training volume for 2 weeks showed a significant increase in [C]. When training volume was tapered, [C] decreased accordingly. However, [T] showed no significant alterations to either the sudden increase in the training or the tapering and cessation of training. In addition, T, C, and T/C shared significant relationships with the physical performance indicators of BJ, PF, and RFD.
Relationships between field fitness test and basal serum testosterone and cortisol levels in soccer players.
The aim of this study was to investigate the existence of a relationship between performance capacities and blood levels of testosterone (T) and cortisol ©. Thirty-two professional soccer players volunteered for the study. Morning levels of hormones were plotted against results of maximal vertical jump with a preparatory counter-movement (CMJ), 30 m running, and Cooper’s 12-min running test. The serum T was positively related to both CMJ and average running speed (r=0.43 and r=0.47, respectively). Serum levels of C and T were in negative correlation (r= -0.40 and r= -0.49, respectively) with the results of Cooper’s test. It was concluded that athletes with better explosive strength and sprint running performances have a higher basal level of testosterone. The results suggest a relationship between testosterone production and development of fast twitch muscle fibres in athletes.
Is testosterone influencing explosive performance?
The primary objective of this study was to analyze the relationship between testosterone levels and vertical jumping performance in elite men and women athletes. The secondary objective was to verify whether testosterone levels and vertical jumping performance were different in men and women athletes and if those measurements were different between different athletic groups. Seventy (22 women and 48 men) elite athletes in track and field (sprinters), handball, volleyball, and soccer competing at national and international levels participated in the study. After 10 hours of fasting and 1 day of rest, blood samples were drawn from the antecubital vein for determining testosterone levels. Vertical jumping tests consisted of countermovement jumps conducted on a resistive platform connected to a digital timer. Resting testosterone levels in women were 9.5% of those of the men (respectively 0.62 +/- 0.06 ng.ml(-1) and 6.49 +/- 0.37 ng.ml(-1); p < 0.001). Countermovement jump performance was significantly different between women and men athletes, with women’s jumping ability 86.3% of that of men (p < 0.001). A significant positive relationship was identified between testosterone levels and vertical jump performance when all data where considered (r = 0.61, p < 0.001, n = 70).
A Hypothesis Of Testosterone Effect on Power Performance
Abstract
Testosterone is known by its effect on myofibrillar hypertrophy. However, results of several studies show significant correlation between blood level of testosterone and performance in power exercises. The testosterone action of synthesis of myofibrillar proteins requires more than one hour. Therefore, the relationship of testosterone level and performance has to be founded on another mechanism. A hypothesis of pre-conditioning has been formulated, which assumes the casual relationship of individual rate of testosterone secretion(1) pubertal development of fast twitch fibres, and (2) functioning of fast motor units. The latter may ensure a ‘tuning’ of motor centres in the central nervous system for explosive performance.
Should sprinters be looking to drive testosterone as high as possible? Thoughts?
