Creatine/Glycerol and Creatine/Glycerol/Alpha- lipoic acid supplements: impact on hyperhydration, thermoregulatory and cardiovascular responses during exercise in the heat and cardiometabolic risk factors

Polyviou, Thelma (2012) Creatine/Glycerol and Creatine/Glycerol/Alpha- lipoic acid supplements: impact on hyperhydration, thermoregulatory and cardiovascular responses during exercise in the heat and cardiometabolic risk factors. PhD thesis, University of Glasgow.

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Abstract

The use of solutions containing creatine and glycerol (Cr/Gly) has become popular amongst athletes as a means of hyperhydrating prior to exercise in the heat, since achieving an optimal hydration status appears to be a critical factor for temperature and cardiovascular regulation during exercise in the heat. Hyperhydration has previously been achieved by means of a pre-exercise water loading strategy with the use of hydrating agents (i.e., Cr and Gly) in combination. Certain problems are related to this hyperhydration strategy and are investigated in this thesis. Firstly, the use of Gly has been prohibited and added to the WADA banned list due to the potential of Gly plasma expansion properties, to mask the use of doping substances such as erythropoietin stimulants. However, the scientific basis of the inclusion of Gly as a “masking agent” remains inconclusive. Secondly, the addition of high CHO amounts to the Cr/Gly strategy is central to successful Cr uptake and subsequent hyperhydration. Thirdly, high CHO intake has been linked to high plasma TAG in the athletic population and partial replacement of CHO with insulinotropic agents, such as alpha lipoic acid (Ala), a natural antioxidant and co-factor in the pyruvate dehydrogenase complex, has been shown to enhance Cr uptake under conditions of reduced CHO. On a separate note, Cr and Ala have been found to individually improve Glu tolerance and lipid markers in sedentary individuals while the combined effects of Cr/Ala supplementation on Glu tolerance and lipid markers of sedentary individuals have not been investigated. The aim of chapter 3 was to determine the effects of a hyperhydrating supplement containing 1.0 g/kg of BM of Gly, 10.0 g of Cr and 75.0 g of Gluon on doping-relevant blood parameters. This hyperhydration did not significantly alter PV or any of the doping-relevant blood parameters (e.g., Hct, [Hb], Ret (%) and tHb-mass). Due to the fact that most athletes, in situations where they may be subject to testing by WADA, may choose rapid hyperhydration protocols, the effects of a shorter supplementation 2 protocol on doping related blood parameters, was investigated in chapter 3. For this purpose, a separate cohort of participants consumed the Gly/Cr/Glu supplement over the course of one day. Despite a significant increase in BM over the course of supplementation lasting 8 hours, PV changes and the blood-relevant doping markers of interest were not significantly affected, even when urinary [Gly] was clearly above the urinary [Gly] observed following typical dietary Gly intake. In conclusion, this study showed that supplementation with a hyperhydrating solution containing Gly for 7 days or a short supplementation protocol lasting one day did not significantly alter doping- relevant blood parameters. The aim of chapter 4 was to determine whether Cr/Gly-induced thermoregulatory and cardiovascular responses are maintained when part of the Glu in the Cr/Gly supplement is replaced with the insulintropic agent Ala. Median and range values of TBW increased significantly by 2.1 (1.3-3.3) L and 1.8 (0.2-4.6) L in the Cr/Gly/Glu and Cr/Gly/Glu/Ala groups, respectively (P=0.03). During constant load exercise, HR and Tcore were significantly lower post-supplementation: HR was reduced on average by 3.3±2.1 beats/min and by 4.8±3.3 beats/minute (mean±S.D.) and Tcore by 0.2±0.1 (mean±S.D.) in the Cr/Gly/Glu and Cr/Gly/Glu/Ala groups, respectively. The reduction in HR and Tcore was not significantly different between the supplementation groups. In comparison to the established hyperhydrating Cr/Gly/Glu supplement, a supplement containing Cr/Gly/Ala and decreased amount of Glu provides equal improvements in thermoregulatory and cardiovascular responses during exercise in the heat. The aim of chapter 5 was to determine whether acutely increasing dietary CHO intake prior to endurance events, through the intake of hyperhydrating Cr/Gly solution enriched with Glu, leads to changes in plasma lipids of endurance trained cyclists and whether replacing part of the Glu within this supplement with an insulin potentiating agent, such as Ala, attenuates these changes. Fasting concentration of TAG increased significantly 3 (P<0.01) after supplementation with Cr/Gly/Glu (Pre, 0.9±0.2 mmol/L; Post, 1.3±0.4 mmol/L) and Cr/Gly/Glu/Ala (Pre, 0.8±0.2 mmol/L; Post 1.2±0.5 mmol/L) but the increase in plasma TAG concentration was not significantly different between the two groups. Supplementation had no effect on fasting concentration of total-, HDL-, and LDL- cholesterol and insulin resistance. The acute increase in dietary CHO intake during the 7 days of supplementation with Cr/Gly/Glu induces an increase in plasma TAG concentration that is not attenuated by partial replacement of CHO with Ala. The aim of chapter 6 was to determine whether Cr supplementation, in the absence of exercise would lead to improvements in Glu tolerance in healthy overweight sedentary males and if Cr supplementation combined with Ala, would improve Glu tolerance and plasma lipids in healthy overweight sedentary males. The purpose of this pilot study was to determine the efficacy of Cr and Cr/Ala combined supplementations in improving Glu tolerance, insulin sensitivity and lipid profile of healthy overweight sedentary males. A four-week supplementation with Cr improved Glu tolerance while supplementation with Cr/Ala failed to have such an effect. Nevertheless, supplementation with Cr/Ala for 4 weeks decreased LDL-cholesterol significantly. None of the other blood markers were significantly different following 4 weeks of supplementation with Cr or Cr/Ala. This study found that Cr improved Glu tolerance without any changes in insulin sensitivity or lipid profile of healthy overweight sedentary males, in the absence of exercise. Moreover, the addition of Ala to Cr, had no added effect on Glu uptake, insulin sensitivity or plasma lipids apart from LDL-cholesterol. However, a randomised control trial with a higher sample size, recruiting both experimental, and control groups should be carried out to confirm these findings.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QP Physiology
Colleges/Schools: College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences > Exercise Physiology/Sports Medicine
Funder's Name: UNSPECIFIED
Supervisor's Name: Pitsiladis, Dr. Yannis and Malkova, Dr. Dalia
Date of Award: 2012
Depositing User: Dr Thelma Polyviou
Unique ID: glathesis:2012-4455
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 16 Jul 2013 15:43
Last Modified: 22 Apr 2016 14:55
URI: http://theses.gla.ac.uk/id/eprint/4455

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