Fat Oxidation Rate as a Function of Plasma Lipid and Hormone Response in Endurance Athletes.

Soria, M, Ansón, M, Lou-Bonafonte, JM, Andrés-Otero, MJ, Puente, JJ, and Escanero, J. Fat oxidation rate as a function of plasma lipid and hormone response in endurance athletes. J Strength Cond Res 34(1): 104-113, 2020-Plasma lipid changes during incremental exercise are not well known. The aim of this study was to investigate the relationship among fat oxidation rate, plasma lipids, and hormone concentrations in well-trained athletes. Twenty-six trained triathletes completed a graded cycle ergometer test to exhaustion increasing by 0.5 W·kg every 10 minutes. Fat oxidation rates were determined using indirect calorimetry. For each individual, maximal fat oxidation (MFO), the intensity at which MFO occurred (Fatmax), and the intensity at which fat oxidation became negligible (Fatmin) were determined. Blood samples for lipids and hormones analysis were collected at the end of each stage of the graded exercise test. All variables studied except insulin showed an increase at the end of incremental protocol with respect to basal levels. Free fatty acid reached significant increase at 60%VO2max and maximal levels at 70%VO2max. Low-density lipoprotein (LDL) and triglycerides (TG) decreased and showed lowest levels at 60%VO2max and reaching significant increases after 80%VO2max. High-density lipoprotein reached significant increase at 60%VO2max. Adrenaline and noradrenaline increased until the end of the incremental exercise, and significant differences were from 50%VO2max. These results suggest that exercise intensities are related to plasma lipids levels. In the zone when lipids oxidation is maximal, plasma LDL and TG variation differs from other lipids. These results may have application for the more adequate exercise intensity prescription to maximize the beneficial effects of exercise.

Correlation Analysis of Exercise-Induced Changes in Plasma Trace Element and Hormone Levels During Incremental Exercise in Well-Trained Athletes.

This study analyzes the relationship between hormonal changes induced by exercise and variations in trace elements associated with oxidative stress during incremental exercise. Nineteen well-trained endurance athletes performed a cycle ergometer test: after a warm-up of 10 min at 2.0 W kg(-1), workload increased by 0.5 W kg(-1) every 10 min until exhaustion. The analysis was controlled for prior diet and activity patterns, levels of exercise training, and time of day (circadian rhythms). Whole blood lactate concentration and plasma concentrations of ions (Zn, Se, Mn, and Co), insulin, glucagon, aldosterone, thyroid stimulating hormone (TSH), calcitonin, and parathyroid hormone (PTH) were measured at rest; at the end of each stage; and 3, 5, and 7 min post-exercise. The statistical analysis involved paired non-parametric tests and correlation coefficients. No significant differences were found in Mn or Co levels as a function of exercise intensity. Zn and Se levels at the end of the exercise protocol and over the recovery time were significantly different to baseline. Further, Zn levels were significantly correlated with aldosterone, calcitonin, and PTH levels, while Se levels were associated with aldosterone, calcitonin, and TSH levels. Our results indicate several different patterns of association between acute changes in hormone concentrations and variations in trace element concentrations related to oxidative stress during submaximal exercise.

Plasma levels of trace elements and exercise induced stress hormones in well-trained athletes.

This study analyzed the variation and relationship of several trace elements, metabolic substrates and stress hormones activated by exercise during incremental exercise. Seventeen well-trained endurance athletes performed a cycle ergometer test: after a warm-up of 10 min at 2.0 W kg(-1), the workload was increased by 0.5 W kg(-1) every 10 min until exhaustion. Prior diet, activity patterns, and levels of exercise training were controlled, and tests timed to minimize variations due to the circadian rhythm. Oxygen uptake, blood lactate concentration, plasma ions (Zn, Se, Mn and Co), serum glucose, non-esterified fatty acids (NEFAs) and several hormones were measured at rest, at the end of each stage and 3, 5 and 7 min post-exercise. Urine specific gravity was measured before and after the test, and participants drank water ad libitum. Significant differences were found in plasma Zn and Se levels as a function of exercise intensity. Zn was significantly correlated with epinephrine, norepinephrine and cortisol (r = 0.884, P < 0.01; r = 0.871, P < 0.01; and r = 0.808, P = 0.05); and Se showed significant positive correlations whit epinephrine and cortisol (r = 0.743, P < 0.05; and r = 0.776, P < 0.05). Neither Zn nor Se levels were associated with insulin or glucagon, and neither Mn nor Co levels were associated with any of the hormones or substrate metabolites studied. Further, while Zn levels were found to be associated only with lactate, plasma Se was significantly correlated with lactate and glucose (respectively for Zn: r = 0.891, P < 0.01; and for Se: r = 0.743, P < 0.05; r = 0.831, P < 0.05). In conclusion, our data suggest that there is a positive correlation between the increases in plasma Zn or Se and stress hormones variations induced by exercise along different submaximal intensities in well-hydrated well-trained endurance athletes.

Variations in serum magnesium and hormonal levels during incremental exercise.

In this study, we examined the relationship between plasma magnesium levels and hormonal variations during an incremental exercise test until exhaustion in 27, well-trained, male endurance athletes. After a warm-up of 10 min at 2 W/kg, the test began at an initial workload of 2.5 W/kg and continued with increments of 0.5 W/kg every 10 min until exhaustion. Plasma magnesium, catecholamine, insulin, glucagon, parathyroid hormone (PTH), calcitonin, aldosterone and cortisol levels were determined at rest, at the end of each stage and three, five and seven minutes post-exercise. With the incremental exercise test, no variations in plasma magnesium levels were found, while plasma adrenaline, noradrenaline, PTH, glucagon and cortisol levels increased significantly. Over the course of the exercise, plasma levels of insulin decreased significantly, but those of calcitonin remained steady. During the recovery period, catecholamines and insulin returned to basal levels. These findings indicate that the magnesium status of euhydrated endurance athletes during incremental exercise testing may be the result of the interrelation between several hormonal variations.