Carlos González-Haro

Maximal lipidic power in high competitive level triathletes and cyclists

Objective: To describe the fat-oxidation rate in triathlon and different modalities of endurance cycling. Methods: 34 endurance athletes (15 male triathletes, 4 female triathletes, 11 road cyclists and 4 male mountain bikers) underwent a progressive cycloergometer test until exhaustion. Relative work intensity (VO2max), minimal lactate concentration (La−min), lactic threshold, individual lactic threshold (ILT), maximal fat-oxidation rate (Fatmax, Fatmax zone) and minimal fat-oxidation rate (Fatmin) were determined in each of the groups and were compared by means of one-way analysis of variance. Results: No significant differences were found for Fatmax, Fatmin or for the Fatmax zone expressed as fat oxidation rate (g/min). Intensities −20%, −10% and −5% Fatmax were significantly lower for mountain bikers with respect to road cyclists and female triathletes, expressed as % VO2max. Intensities 20%, 10% and 5% Fatmax were significantly lower for mountain bikers with respect to male triathletes and female triathletes, and for male triathletes in comparison with female triathletes, expressed as % VO2max. Lactic threshold and La−min did not show significant differences with respect to Fatmax. Lactic threshold was found at the same VO2max with respect to the higher part of the Fatmax zone, and La−min at the same VO2max with respect to the lower part of the Fatmax zone. Conclusions: The VO2max of Fatmax and the Fatmax zone may explain the different endurance adaptations of the athletes according to their sporting discipline. Lactic threshold and La−min were found at different relative work intensities with respect to those of Fatmax even though they belonged to the Fatmax zone.

Physiological adaptation during short distance triathlon swimming and cycling sectors simulation

The aim of this study was to typify cardiorespiratory and metabolic adaptation capacity at race pace of high-level triathletes during simulations of short distance triathlon swimming sector, first transition and cycling sector. Six national and international-level triathletes performed a 1500 m swimming trial followed by a transition and one hour on ergocycle at race pace, with sequenced measures of blood lactate concentration, gas exchange and heart rate recording. The mean speed obtained in the swimming sector was 1.29+/-0.07 m s(-1), matching 98+/-2% of MAS (Maximal Aerobic Speed), lactate concentration 6.8+/-2.1 mM and heart rate 162+/-15 beats min(-1). In the cycling sector, the mean power was 266+/-34 W, matching 77+/-10% of MAP (Maximal Aerobic Power), oxygen uptake 3788+/-327 mL min(-1) (82.8% of VO2max), heart rate 162+/-13 beats min(-1) (92% of maximal HR) and ventilation 112.8+/-20.8 L min(-1). MAS was correlated with performance in swimming sector (r = 0.944; P < 0.05). Despite intake 1.08+/-0.44 L of a solution with 8% of sugars, a significant loss of body weight (2.80%; P < 0.01) was observed. Changes in cycling power, speed and frequency, especially towards the end of the effort, were also found. By contrast, differences in lactate concentration and in cardiorespiratory or metabolic variables between the end of the swimming sector and the end of the first transition did not appear. In conclusion, this study remarks different relative intensities in cycling and swimming sectors. The observed loss of body weight does not modify pedalling economy in national and international-level athletes during the cycling sector, where effort intensity adapts itself to the one found in individual lactate threshold. However, changes in competition tactics and other effects, such as drafting in swimming and cycling, could alter the intensities established in this study for each sector.

Validation of a field test to determine the maximal aerobic power in triathletes and endurance cyclists

Objective: To validate a field test to assess the maximal and submaximal exercise aerobic adaptation under specific conditions, for endurance modality cyclists and triathletes. Methods: 30 male and 4 female endurance modality cyclists and triathletes, with heterogeneous performance levels, performed three incremental tests: one in the laboratory and two in the field. Assessment of the validity of the field protocol was carried out by the Student’s t test, intraclass correlation coefficient (ICC) and coefficient of variation (CV) of the maximal variables (maximal aerobic speed (MAS), maximal aerobic power (MAP), maximal heart rate (HRmax), maximal blood lactate concentration ([La−]max) and maximal oxygen uptake (VO2max)) and submaximal variables (heart rate, HR) measured in each one of the tests. The errors in measurement were calculated. The repeatability of the field tests was assessed by means of the test–retest of the two field tests, and the validity by means of the test–retest of the laboratory test with respect to the mean of the two field tests. Results: No significant differences were found between the two field tests for any of the variables studied, but differences did exist for some variables between the laboratory tests with respect to the field tests (MAP, [La−]max, humidity (H), barometric pressure (Pb) and some characteristics of the protocols). The ICC of all the variables was high and the CV for the MAP was small. Furthermore, the measurement errors were small and therefore, assumable. Conclusions: The incremental protocol of the proposed field test turned out to be valid to assess the maximal and submaximal aerobic adaptation.

Comparison of nine theoretic models estimating the mechanical power output in cycling.

Objective: To assess which of the equations used to estimate mechanical power output for a wide aerobic range of exercise intensities gives the closest value to that measured with the SRM training system. Methods: Thirty four triathletes and endurance cyclists of both sexes (mean (SD) age 24 (5) years, height 176.3 (6.6) cm, weight 69.4 (7.6) kg and Vo2max 61.5 (5.9) ml/kg/min) performed three incremental tests, one in the laboratory and two in the velodrome. The mean mechanical power output measured with the SRM training system in the velodrome tests corresponding to each stage of the tests was compared with the values theoretically estimated using the nine most referenced equations in literature (Whitt (Ergonomics 1971;14:419–24); Di Prampero et al (J Appl Physiol 1979;47:201–6); Whitt and Wilson (Bicycling science. Cambridge: MIT Press, 1982); Kyle (Racing with the sun. Philadelphia: Society of Automotive Engineers, 1991:43–50); Menard (First International Congress on Science and Cycling Skills, Malaga, 1992); Olds et al (J Appl Physiol 1995;78:1596–611; J Appl Physiol 1993;75:730–7); Broker (USOC Sport Science and Technology Report 1–24, 1994); Candau et al (Med Sci Sports Exerc 1999;31:1441–7)). This comparison was made using the mean squared error of prediction, the systematic error and the random error. Results: The equations of Candau et al, Di Prampero et al, Olds et al (J Appl Physiol 1993;75:730–7) and Whitt gave a moderate mean squared error of prediction (12.7%, 21.6%, 13.2% and 16.5%, respectively) and a low random error (0.5%, 0.6%, 0.7% and 0.8%, respectively). Conclusions: The equations of Candau et al and Di Prampero et al give the best estimate of mechanical power output when compared with measurements obtained with the SRM training system.

Differences in physiological responses between short- vs. long-graded laboratory tests in road cyclists.

Abstract González-Haro, C. Differences in physiological responses between short- vs. long-graded laboratory tests in road cyclists. J Strength Cond Res 29(4): 1040–1048, 2015—This study aimed to determine the effect of a short-graded with respect to a long-graded protocol laboratory test on the physiological responses of road cyclists. Twenty well-trained road cyclists performed a short-graded and long-graded laboratory tests within 1 week of each other in a randomized and crossover study design. Blood lactate concentration ([La−]b), heart rate (HR), oxygen consumption ( ), and carbon dioxide production ( ) were measured. Fat and carbohydrate oxidation rates (FATOxR and CHOOxR) were estimated at the end of each stage during the short-graded and the long-graded (10th minute: T2.10) and in the middle of long-graded (fifth minute: T2.5) protocol. Lactate threshold (LT) and individual anaerobic threshold (IAT) were calculated. For maximal intensities, duration and maxFATOxR were significantly higher in long-graded with respect to short-graded protocols. Peak power output (POPeak), HRPeak, [La−]bmax, , and maxCHOOxR were significantly higher in short-graded with respect to long-graded protocols. At submaximal intensities, short-graded protocol provoked higher demands on glycolytic metabolism than long-graded protocol; no differences were illustrated for HR or between protocols. Crossover concept shifted to higher intensities in long-graded with respect to short-graded protocols due to the higher lipolytic response during the long-graded protocol. Both LT and IAT were reached at the same % , although significantly higher PO in short-graded with respect to long-graded protocols was reached. The long-graded proved to be more specific than the short-graded protocol to assess the physiological responses of road cyclists based on relative PO (W·kg−1).

Variants of the Solute Carrier SLC16A1 Gene (MCT1) Associated With Metabolic Responses During a Long-Graded Test in Road Cyclists

Abstract González-Haro, C, Soria, M, Vicente, J, Fanlo, AJ, Sinués, B, and Escanero, JF. Variants of the solute carrier SLC16A1 gene (MCT1) associated with metabolic responses during a long-graded test in road cyclists. J Strength Cond Res 29(12): 3494–3505, 2015—Variants of the solute carrier SLC16A1 gene have been associated with alterations in MCT1 expression, because of a lactate (La−) transport deficiency across the cell membrane and a blood La− accumulation. The aim of this study was to associate the allelic and genotypic frequencies of 1470T>A, 2917(1414) C>T, and IVS3-17A>C variants relative to the blood La− kinetics and metabolic responses to a progressive effort until exhaustion. Twenty-five well-trained road cyclists performed a long-graded laboratory test: 10 minutes at 2.0 W·kg−1, first step at 2.5 W·kg−1 with increments of 0.5 W·kg−1 every 10 minutes until exhaustion. Blood La−, nonesterified fatty acids (NEFAS), and glucose levels were measured; fat and carbohydrate oxidation rates were estimated through stoichiometric equations. Three variants of SLC16A1 gene were determined for each subject, which were divided in two groups: wt (wild type)/mt (mutated type) and mt/mt genotype group versus wt/wt genotype group. Metabolic responses were compared between both groups with an unpaired Students t-test; Friedman and Wilcoxon tests were performed for nonparametric data. The statistical significance was set at p ⩽ 0.05. For 1470TA polymorphism, no significant blood La− differences were found between groups. 2197(1414)C>T allele carriers and IVS3-17A>C carriers showed significantly higher blood La− levels, lower blood NEFAS, and glucose levels at submaximal intensities. These findings open a new perspective to investigate SLC16A1 variants (1470TA and IVS3-17A>C) on La− deficiency transport and its regulation/interaction with other metabolic pathways. Future studies would be needed to clarify whether 1470T>A, 2917(1414)C>T, and IVS3-17A>C allelic/genotypic distribution benefit performance in endurance athletes.

Submaximal exercise intensities do not provoke variations in plasma magnesium concentration in well-trained euhydrated endurance athletes with no magnesium deficiency.

The purpose of this study was to assess the effect of exercise intensity during an incremental exercise test on plasma Mg concentration in well-trained euhydrated athletes. Twenty-seven well-trained endurance athletes carried out a cycloergometer test: after a warm-up of 10 min at 2.0 W·kg(-1), the workload increased by 0.5 W·kg(-1) every 10 min until exhaustion. Oxygen uptake (VO(2)), blood lactate concentration ([La(-)](b)), catecholamines, and plasma Mg were measured at rest, at the end of each stage and at 3, 5 and 7 minutes post-exercise. Urine specific gravity (U(SG)) was analyzed before and after the test, and subjects drank water ad libitum. Fat oxidation rate (FAT(oxr)), carbohydrate oxidation rate (CHO(oxr)), energy expenditure from fat (EE(FAT)), energy expenditure from carbohydrate (EE(CHO)), and total EE (EE(TOTAL)) were estimated using stoichiometric equations. Plasma Mg concentration at each relative exercise intensity (W·kg(-1)) were compared by means of repeated-measures ANOVA. Pearsons correlations were performed to assess the relationship between variables. The significance level was set at p<0.05. No significant differences were found in U(SG) between before and after the test (1.014±0.004 vs 1.014±0.004 g·cm(-3)). Nor were significant differences found in plasma Mg as a function of the different exercise intensities. Further, no significant correlations were detected between Mg and metabolic variables. In conclusion, acute exercise at a range of submaximal intensities in euhydrated well-trained endurance athletes does not affect plasma Mg concentration, suggesting that the plasma volume plays an important role in Mg homeostasis during exercise.

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.