Search results for "testosterone"

Data from: Maintenance costs of male dominance and sexually antagonistic selection in the wild

2019

1. Variation in dominance status determines male mating and reproductive success, but natural selection for male dominance can be detrimental or antagonistic for female performance, and ultimately their fitness. Attaining and maintaining a high dominance status in a population of competing individuals is physiologically costly for males. But how male dominance status is mediated by maintenance energetics is currently not well understood, nor are the correlational effects of male energetics on his sisters recognized. 2. We conducted laboratory and field experiments on rodent populations to test whether selective breeding for male dominance status (dominant vs. subordinate breeding lines) ant…

Effects of combined hormone replacement therapy or its effective agents on the IGF-1 pathway in skeletal muscle.

2010

Objectives To investigate the effects of combined hormone replacement therapy (HRT) and its effective agents on the IGF-1 signaling pathway. Design and methods To examine the effects of HRT on skeletal muscle in vivo, we utilized pre- and post-intervention samples from a randomized double blinded trial with 50–57-year-old women. The intervention included the year-long use of either HRT preparation (2 mg 17β-estradiol, E2; 1 mg norethisterone acetate, NETA, n = 10) or placebo (CO, n = 9). Microarray technology and quantitative PCR (qPCR) were used to study the expression of insulin-like growth factor I (IGF-1) and its splice variants as well as IGF-1 receptor, Akt1, mTOR, FOXO1, FOXO3, atrog…

Acute responses of comprehensive gonadosteroids and corticosteroids to resistance exercise before and after 10 weeks of supervised strength training

2020

Resistance training is a potent stimulus for muscle growth and steroid hormones are known to play a role in this adaptation. However, very little is known about the acute exercise‐induced gonadosteroid and corticosteroid hormone responses, including key smaller‐concentration intermediate hormones. The present study determined the acute responses of these steroid hormone families using quantitative UHPLC mass spectrometry (MS) following resistance exercise in strength‐trained men. Venous and fingertip blood was drawn pre‐, mid‐, 5 min post‐ and 15 min post‐resistance exercise, both before and after 10 weeks of supervised resistance training. The experimental resistance exercise sessions cons…

Influence of Oral Contraceptive Use on Adaptations to Resistance Training

2019

Introduction: The majority of young women use oral contraceptives (OCs). Use of OCs has been associated with lower myofibrillar protein and tendon collagen synthesis rates, but it is unknown whether OCs will limit the adaptive response of myotendinous tissue to resistance training. Design and Methods: Fourteen healthy untrained young regular OC users (24 +/- 1 years, fat% 32 +/- 1, 35 +/- 2 ml.min(-1).kg(-1)) and 14 NOC users (non-OC, controls) (24 +/- 1 years, fat% 32 +/- 2, 34 +/- 2 ml.min(-1).kg(-1)) performed a 10-week supervised lower extremity progressive resistance training program. Before and after the intervention biopsies from the vastus lateralis muscle and the patellar tendon we…

Acute neuromuscular and endocrine responses and recovery to single session combined endurance and strength loadings: ‘Order effect’ in untrained youn…

2013

The purpose of this study was to investigate acute neuromuscular and endocrine responses and recovery to a single session of combined endurance and strength loading using two loading orders. Forty-two men were demographically matched to perform a single session of combined endurance+strength (E+S) or strength+endurance (S+E) loading. The strength loading was conducted on a leg press and included sets of power, maximal strength and hypertrophic loads with an overall duration of 30 minutes. The endurance loading was conducted on a bike ergometer and performed by continuous cycling over 30min at 65% of subject’s individual maximal Watts. Both loading conditions led to significant acute reducti…

Maternal antibody transmission and breeding densities in the Black-headed Gull Larus ridibundus

2004

1. The offspring of avian species, especially those of colonial breeders, are exposed to a number of pathogens immediately after birth. The chick's immune system is, at that early stage still immature and inefficient. As a consequence, diseases can have a strong impact on chick survival.2. The ability of mothers to transmit passive immunity in terms of antibodies of their own acquired immunity to their chicks is probably an essential pathway to enhance the chick survival. Since the production of antibodies is costly, females are expected to adjust the transmission of passive immunity to the local disease environment.3. We found that in Black-headed Gulls (Larus ridibundus L.) yolk antibody …

Immune system adaptations during competition period in female cross-country skiers

2011

Stenholm, Johanna. Immune system adaptations during competition period in female cross-country skiers. Master’s Thesis in Exercise Physiology, Department of Biology of Physical Activity. University of Jyväskylä. 95pp. Purpose. This study was undertaken to characterize the extent of immune and endocrine changes in competition period and related to two competition weekends in well trained athletes in different parts of the competition period. An additional purpose was to evaluate if the changes in immunological variables would have an effect on the incidence of upper-respiratory-tract infections. The effect of the nutrition, nutrient and training status was also studied. Methods. Ten (10) nat…

Alcohol Abuse Mediates the Association between Baseline T/C Ratio and Anger Expression in Intimate Partner Violence Perpetrators.

2015

The imbalance between testosterone (T) and cortisol (C) levels has been proposed as a possible marker of risk for intimate partner violence (IPV). Moreover, it could be related to a high probability of adopting risky behaviors such as alcohol abuse which, in turn, promotes the onset of IPV. This study tested the potential mediating effect of alcohol consumption on the relationship between baseline T/C ratio and anger expression in IPV perpetrators and non-violent controls. Alcohol consumption was higher in the former than controls. A high baseline T/C ratio was only associated with high anger expression in IPV perpetrators, and this association was mediated by high alcohol consumption. Thus…

Evolutionary conflicts in a small mammal : behavioural, physiological and genetic differences between the sexes

2011

Decreased prevalence of left-handedness among females with male co-twins: Evidence suggesting prenatal testosterone transfer in humans?

2010

Studies of singletons suggest that right-handed individuals may have higher levels of testosterone than do left-handed individuals. Prenatal testosterone levels are hypothesised to be especially related to handedness formation. In humans, female members from opposite-sex twin pairs may experience elevated level of prenatal exposure to testosterone in their intrauterine environment shared with a male. We tested for differences in rates of left-handedness/right-handedness in female twins from same-sex and opposite-sex twin pairs. Our sample consisted of 4736 subjects, about 70% of all Finnish twins born in 1983–1987, with information on measured pregnancy and birth related factors. Circulatin…