Gender differences in the endocrine and metabolic responses to hypoxic exercise

Abstract

Sandoval, Darleen A., and Kathleen S. Matt. Gender differences in the endocrine and metabolic responses to hypoxic exercise. J Appl Physiol 92: 504-512, 2002; 10.1152/ japplphysiol.00526.2001.-This study tested the hypothesis that women would have blunted physiological responses to acute hypoxic exercise compared with men. Fourteen women taking oral contraceptives (28 Ϯ 0.9 yr of age) and 15 men (30 Ϯ 1.0 yr of age) with similar peak O 2 consumption (V O2 peak) values (56 Ϯ 1.1 vs. 57 Ϯ 0.8 ml ⅐ kg fat-free mass Ϫ1 ⅐ min Ϫ1 ) were studied under hypoxic (H; fraction of inspired oxygen ϭ 13%) vs. normoxic (fraction of inspired oxygen ϭ 20.93%) conditions. Cardiopulmonary, metabolic, and neuroendocrine measures were taken before, during, and 30 min after three 5-min consecutive workloads at 30, 45, and 60% V O2 peak. In women compared with men, glucose levels were greater during recovery from H (P Ͻ 0.05) and lactate levels were lower at 45% V O2 peak, 60% V O2 peak, and up to 20 min of recovery (P Ͻ 0.05), regardless of trial (P Ͻ 0.0001). Although the women had greater baseline levels of cortisol and growth hormone (P Ͻ 0.0001), gender did not affect these hormones during H or exercise. Catecholamine responses to H were also similar between genders. Thus the endocrine response to hypoxia per se was not blunted in women as we had hypothesized. Other mechanisms must be at play to cause the gender differences in metabolic substrates in response to hypoxia. catecholamines; cortisol; metabolites LIMITED RESEARCH HAS EXAMINED the impact of gender on hormonal and metabolic responses to acute hypoxic exercise. Recent extensive studies have examined the effects of chronic hypoxia in women during different phases of the menstrual cycle (2, 3, 24). However, these studies were not examining the impact of gender per se, because they lacked a comparably fit male control group. Nevertheless, metabolic differences do seem to exist after acclimatization to 4,300 m, with women shifting toward greater fat (3) and men shifting toward greater carbohydrate use (29) during exercise. In normoxia (Յ1,500 m), gender does alter the sympathetic and metabolic responses to prolonged (8,15,33) and supramaximal exercise (11). For example, women have a greater reliance on fat oxidation and a blunted plasma catecholamine response during exercise at the same relative intensity compared with men with similar fitness levels (8,11,15,33). In addition, women, compared with men, also have a reduced plasma catecholamine response to hypoglycemic (7) and cognitive stressors (21), possibly due to a direct inhibitory effect of estradiol on the sympathetic nervous system (SNS) (6). Yet it remains unknown whether plasma catecholamine responses differ between comparably fit men and women during acute hypoxic exercise. It seems plausible that SNS response to the stress of acute hypoxic exercise will also be different between genders, with the prediction that women will have a lower plasma catecholamine response compared with men.The hypothalamic-pituitary-adre...

Aerobic fitness of elite female and male wrestlers

“…-----Similar findings, reflecting the gender difference, were reported by Sandoval et al [22] after 5 min cycling corresponding to 60%VO 2 max in recreationally active men and women, and they postulated that if women were using less glycogen during exercise than they would produce less lactate. Moreover Sargent et al [23] noted that in untrained men lactate concentration reached higher values then in untrained women after cessation of incremental exercise test.…”

“…However, investigation of the effect of gender on exercise substrate utilization yielded conflicting results. The mechanisms for these gender-based differences are still not fully understood, but it was postulated that substrate metabolism can be influenced by the catecholamines and female sex hormones [22], body fat content, percent of fiber type area and training experience [21]. Elis et al [9] revealed that estradiol increases the availability of lipids to exercising muscle due to an increase in muscle lipoprotein lipase activity.…”

Hypoxic training: Clinical benefits on cardiometabolic risk factors

“…Secretion of epinephrine has been suggested to be responsible for the rise in blood glucose levels and reduction in insulin sensitivity [14,15], however in one study, epinephrine levels remained unchanged despite a rise in blood glucose, indicating alternative metabolic signalling pathways [17]. Additionally hormones such as oestrogen may affect the response to hypoxic training as seen with gender differences in glucose response to hypoxic training [17]. Current studies favour a chronic, moderate level of hypoxic training (1,500m to 2,500m) used with moderate level of exercise intensity (55% -65% HR max ) to improve blood glucose regulation.…”

“…It would also suggest that patients with issues with blood regulation should monitor their blood glucose status when participating in hypoxic training involving high exercise intensities or high levels of hypoxia. Secretion of epinephrine has been suggested to be responsible for the rise in blood glucose levels and reduction in insulin sensitivity [14,15], however in one study, epinephrine levels remained unchanged despite a rise in blood glucose, indicating alternative metabolic signalling pathways [17]. Additionally hormones such as oestrogen may affect the response to hypoxic training as seen with gender differences in glucose response to hypoxic training [17].…”

“…However, in a case study, a patient with type 1 diabetes found increased fasting glucose levels of 60% despite maintaining caloric intake [16]. The increase in blood glucose level was reported to be gender specific, with females affected more than males [11,17]. Impaired blood glucose regulation occurred when hypoxic training was performed with high intensive training of incremental durations of maximal aerobic power and ventilatory threshold [12], whereas with moderate intensity of exercise, glucose tolerance and insulin sensitivity depended on level of altitude where moderate levels produced increased glucose metabolism [6] while higher altitude (>3,000m) resulted in impairment in blood glucose regulations [10,11,16].…”