Sixteen men completed four trials at random as follows: (Trial A) performance of a single bout of resistance exercise preceded by placebo ingestion (vitamin C); (Trial B) ingestion of 1,500 mg L-arginine and 1,500 mg L-lysine, immediately followed by exercise as in Trial A; (Trial C) ingestion of amino acids as in Trial B and no exercise; (Trial D) placebo ingestion and no exercise. Growth hormone (GH) concentrations were higher at 30,60, and 90 min during the exercise trials (A and B) compared with the resting trials (C and D) (p < .05). No differences were noted in [GH] between the exercise trials. [GH] was significantly elevated during resting conditions 60 min after amino acid ingestion compared with the placebo trial. It was concluded that ingestion of 1,500 mg arginine and 1,500 mg ly sine immediately before resistance exercise does not alter exercise-induced changes in [GH] in young men. However, when the same amino acid mixture is ingested under basal conditions, the acute secretion of GH is increased.
Richard R. Suminski, Robert J. Robertson, Fredric L. Goss, Silva Arslanian, Jie Kang, Sergio DaSilva, Alan C. Utter, and Kenneth F. Metz
Simon Fryer, Tabitha Dickson, Stephen Hillier, Lee Stoner, Carl Scarrott, and Nick Draper
Venipuncture is expensive, invasive, and impractical for many sport-science and clinical-based settings. Salivary free cortisol is often cited as a noninvasive practical alternative. However, when cortisol concentrations exceed the corticosteroid-binding globulin (CBG) point of 500 nmol/L, a lack of agreement between salivary and venous blood cortisol has been found. Alternatively, capillary blood may present a minimally invasive, cost-effective, and practical surrogate for determining cortisol concentration.
The aim of this study was to determine whether cortisol concentrations sampled from capillary blood and saliva accurately reflect those found in venous blood across a large range of concentrations after intense exercise.
Eleven healthy aerobically trained male subjects were recruited. Capillary, salivary, and venous blood samples were collected before and after (immediately and 5, 10, 15, and 20 min after) a treadmill VO2 max test.
Capillary and venous concentrations increased at a similar rate after exercise (Cohen d.14–.33), increasing up to 15 min postexercise before a decline was seen. Salivary cortisol values increased at a slower rate than venous and capillary cortisol but continued to increase 15 min postexercise (Cohen d .19–.47 and .09–.72, respectively).
Capillary cortisol accurately reflects concentrations assayed from venous blood across a range of values below and above the CBG binding point. Capillary sampling provides a minimally invasive, cost-effective, practical surrogate for assessment of hypothalamic-pituitary-gland function.
Ioanna Athanasiadou, Sven Christian Voss, Wesal El Saftawy, Hind Al-Jaber, Najib Dbes, Sameera Al-Yazedi, Waseem Samsam, Vidya Mohamed-Ali, Mohammed Alsayrafi, Georgia Valsami, and Costas Georgakopoulos
Luteinizing hormone (LH) is a glycoprotein with an approximate molecular weight of 28.5 kDa. It is physiologically produced and secreted by the gonadotropic cells in the anterior pituitary gland. This heterodimer protein is composed of two polypeptide chains, alpha and beta. Nonetheless, only the
Diego de Alcantara Borba, Eduardo da Silva Alves, João Paulo Pereira Rosa, Lucas Alves Facundo, Carlos Magno Amaral Costa, Aldo Coelho Silva, Fernanda Veruska Narciso, Andressa Silva, and Marco Túlio de Mello
. Tissue responsiveness to IGF-1 is altered with age, therefore being associated with a decreased number and phosphorylation of IGF-1 muscle receptors. 43 The increase in GH release by the pituitary gland and its hepatic action and muscle production are the causes most frequently mentioned as being
Nura Alwan, Samantha L. Moss, Kirsty J. Elliott-Sale, Ian G. Davies, and Kevin Enright
provide negative feedback to the hypothalamus and pituitary glands, leading to suppression of follicle-stimulating hormone, luteinizing hormone, and gonadotropin-releasing hormone, and continuous down-regulation of endogenous estrogen and progesterone ( Elliott-Sale et al., 2013 ). Previous data in FP
Travis Anderson, Laurie Wideman, Flavio A. Cadegiani, and Claudio E. Kater
adrenocorticotropic hormone (ACTH) output by the anterior pituitary gland, it is possible that the lowered reactivity of the axis is due generally to a reduced ACTH output (and potentially hypothalamic output of the corresponding releasing hormone) in response to awakening in the OTS group. Regrettably, it is not