Thermoregulatory and cardiovascular responses to creatine, glycerol and alpha lipoic acid in trained cyclists

Abstract

BackgroundIt has been shown that supplementation with creatine (Cr) and glycerol (Gly), when combined with glucose (Glu) necessary for the enhancement of Cr uptake by skeletal muscle, induces significant improvements in thermoregulatory and cardiovascular responses during exercise in the heat.PurposeTo determine whether Cr/Gly-induced thermoregulatory and cardiovascular responses are maintained when the majority (~75%) of the Glu in the Cr/Gly supplement is replaced with the insulintropic agent alpha lipoic acid (Ala).Methods22 healthy endurance trained cyclists were randomly assigned to receive either 20 g/day (4 × 5 g/day) of Cr, 2 g .kg-1 BM per day (4 × 0.5 g .kg-1 BM per day) of Gly and 150 g/day (4 × 37.5 g/day) of Glu or 20 g/day (4 × 5 g/day) of Cr monohydrate, 2 g .kg-1 BM per day (4 × 0.5 g .kg-1 BM per day) of Gly (100 g/day (4 × 25 g/day) of Glu and 1000 mg/day (4 × 250 mg/day) of Ala for 7 days for 7 days. Exercise trials were conducted pre- and post-supplementation and involved 40 min of constant-load cycling exercise at 70% O2 max by a self-paced 16.1 km time trial at 30°C and 70% relative humidity.ResultsMedian and range values of TBW increased significantly by 2.1 (1.3-3.3) L and 1.8 (0.2-4.6) L in Cr/Gly/Glu and Cr/Gly/Glu/Ala groups respectively (P = 0.03) and of BM not significantly by 1.8 (0.2-3.0) kg and 1.2 (0.5-2.1) kg in Cr/Gly/Glu and in Cr/Gly/Glu/Ala, respectively (P = 0.75). During constant load exercise, heart rate (HR) and core temperature (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/min (mean ± SD) and Tcore by 0.2 ± 0.1 (mean ± SD) in the Cr/Gly/Glu and Cr/Gly/Glu/Ala, respectively The reduction in HR and Tcore was not significantly different between the supplementation groups.ConclusionsIn comparison to the established hyper hydrating Cr/Gly/Glu supplement, supplement containing Cr/Gly/Ala and decreased amount of Glu provides equal improvements in thermoregulatory and cardiovascular responses during exercise in the heat.

The effects of creatine supplementation on thermoregulation and physical (cognitive) performance: a review and future prospects

“…In agreement with Easton et al (2007), BM and TBW increased and while HR and core temperature (T core ) were attenuated, no overall difference were seen in O 2 , RE or in serum osmolarity and plasma volume. Polyviou et al (2012) extended this research and reported that Cr combined with Gly and α-lipoic acid (Ala) had similar effects as the Cr/Gly/glucose combination used by Easton et al (2007) when performing constant load exercise in the heat followed by a 10-mile time trial in a hot humid environment. Despite the fairly consistent effects of Cr-induced hyperhydration (with and without enhancement by other hyperhydrating compounds) on thermoregulatory and cardiovascular responses in the previous studies described, exercise performance in the heat was not enhanced (Kilduff et al 2004;Easton et al 2007;Beis et al 2011;Polyviou et al 2012).…”

“…No effects on core temperature compared to placebo Reduced plasma volume loss during 1 hour of hyperthermic submaximal exercise Cognitive performance and neuroprotection Jones et al 2009Tan, 2014Haussinger et al 1993 Francaux and Poortmans 1999; Saab et al 2002Kilduff et al 2003Kilduff et al 2004;Easton et al 2007;Beis et al 2011;Polyviou et al 2012Tarnopolsky et al 1997Andrews et al 1998;Hespel et al 2001Fuld et al 2005Easton et al 2009Bennett et al 2001Branch et al 2007 Increase in psychomotor, complex cognitive task and motor skill performance post-sleep deprivation Some evidence of neuroprotection Reduced hypoxic brain damage McMorris et al 2006;McMorris et al 2007;Cook et al 2011Turner et al 2015Carter et al 1995 Footnote: All studies presented in Table 1 are human studies with the exception of Carter et al 1995 and who used in vitro animal models…”

“…In particular, it is hypothesised that a Cr-induced increase in intracellular water (ICW) enhances the specific heat capacity of the body, resulting in a greater capacity to store heat (Kilduff et al 2004). These cardiovascular and thermoregulatory effects of Cr can be further enhanced when Cr is co-ingested with hyperhydrating agents such as glycerol (Gly) (Riedesel et al 1987;Kern et al 2001;Magal et al 2003;Easton et al 2007;Polyviou et al 2012).…”

The Effects of Hyperhydrating Supplements Containing Creatine and Glucose on Plasma Lipids and Insulin Sensitivity in Endurance-Trained Athletes

“…Enhancement in muscle Cr content facilitates growth in lean body mass, strength, and high intensity exercise performance [ 4 ]. It also enhances fluid retention and provides the improvement in thermoregulation during exercise in the heat [ 5 , 6 ]. As a consequence of these findings, Cr supplementation has become popular amongst recreational and professional athletes.…”

“…Due to these possible detrimental changes in plasma lipids induced by high glucose (Glu) intake consumed with Cr containing supplements, there has been a search for alternative agents that stimulate insulin secretion and thus may be expected to enhance skeletal muscle Cr uptake. We previously demonstrated that the same increase in total body water and improvement in thermoregulatory and cardiovascular responses during exercise in the heat can be achieved when part of the Glu in the Cr/glycerol (Gly) hyperhydrating supplement is replaced with alpha lipoic acid (Ala) [ 20 ], a compound that has insulin-potentiating activity [ 21 ]. It remains unclear whether expected changes in plasma lipids can be attenuated by partial replacement of Glu with Ala.…”