The effects of combined creatine and glycerol hyperhydration on thermoregulation, metabolism and exercise performance in the heat in endurance trained humans

The primary objective of these series of experiments was to develop an optimal hyperhydration strategy for use during conditions of restricted water access or exercise-induced heat stress. This strategy was composed of two compounds, namely Cr and Gly which each targeted specific body water compartments in order to maximise the volume of retained water. Endurance-trained subjects were recruited to participate in the current series of three experiments, and following Cr/Gly supplementation, body water was estimated by multifrequency bioimpedance and the physiological responses to exercise in the heat (30°C, 70% relative humidity) recorded and compared to pre-supplementation values. The aim of the first study presented in this thesis (Chapter 3(a)) was to examine the effects of combined Cr and Gly supplementation on fluid retention and subsequently the effects on cardiovascular, thermoregulatory and metabolic responses and performance during exercise in the heat. The aim of Chapter 3 (b) was to examine the effects of a novel method of Cr and Gly delivery and ingestion on fluid retention and distribution. Chapter 4 (a) aimed to assess the effects of Cr and Gly supplementation ingested according to the loading protocol described in the previous chapter (6 days of Cr and Gly ingestion, with the final supplement consumed 3 hours prior to measurement) on cardiovascular, thermoregulatory and metabolic responses and performance during exercise in the heat. The aim of the study in Chapter 4 (b) was to examine the effects of extending the period of time between ingestion of the final Cr/Gly supplement on the retention and distribution of fluid. The experiment in chapter 5 compared the effects of the novel Cr and Gly loading protocol established in Chapter 4 (b) on cardiovascular, thermoregulatory and metabolic responses and performance during exercise in the heat. The aim of Chapter 6 was to compare Tc measurements obtained using an ingestible telemetry pill and a tympanic membrane thermometer with those from a rectal thermistor during rest and high intensity exercise conducted in a hot and humid environment (30°C and 70% relative humidity) intended to raise Tc above 39°C

The application of metabolomic profiling to the effects of physical activity

Physical activity and exercise are potent lifestyle interventions for the reduction of several psychosomatic risks, including cardiovascular disease, diabetes and mild-to-moderate depression. The current review describes the studies which have utilised a metabolomics/ metabolite profiling approach in combination with exercise in the period between 1999-2014 in predominantly healthy subjects (N:64) and in a smaller subset of patient cohorts (N:10) between 2011-2014. A broad range of intervention types were used in both healthy and patient cohorts with varying exercise regimes with or without supplement use. Effects on purine metabolism, which have been known for over 40 years, were by far the most well-cited and persistent finding. Other reported effects included observations of: glucocorticoid and androgen metabolism, glycolysis and Krebs cycle, gluconeogenesis, fatty acid metabolism, fatty acid oxidation and pantothenic acid, amino acid oxidation, tryptophan metabolism and effects on microbiome metabolites. The discussion section draws observations from the very disparate studies together and links them to the general aspects of human metabolism

Interval running with self-selected recovery:Physiology, performance and perception

Item previously deposited in UWS repository at: https://research-portal.uws.ac.uk/en/publications/interval-running-with-self-selected-recovery-physiology-performanItem not available in this repository.Rosie Arthur – ORCID: 0000-0003-0651-4056 https://orcid.org/0000-0003-0651-4056This study (1) compared the physiological responses and performance during a high-intensity interval training (HIIT) session incorporating externally regulated (ER) and self-selected (SS) recovery periods and (2) examined the psychophysiological cues underpinning SS recovery durations. Following an incremental maximal exercise test to determine maximal aerobic speed (MAS), 14 recreationally active males completed 2 HIIT sessions on a non-motorised treadmill. Participants performed 12 × 30 s running intervals at a target intensity of 105% MAS interspersed with 30 s (ER) or SS recovery periods. During SS, participants were instructed to provide themselves with sufficient recovery to complete all 12 efforts at the required intensity. A semi-structured interview was undertaken following the completion of SS. Mean recovery duration was longer during SS (51 ± 15 s) compared to ER (30 ± 0 s; p < .001; d = 1.46 ± 0.46). Between-interval heart rate recovery was higher (SS: 19 ± 9 b min−1; ER: 8 ± 5 b min−1; p < .001; d = 1.43 ± 0.43) and absolute time ≥90% maximal heart rate (HRmax) was lower (SS: 335 ± 193 s; ER: 433 ± 147 s; p = .075; d = 0.52 ± 0.39) during SS compared to ER. Relative time ≥105% MAS was greater during SS (90 ± 6%) compared to ER (74 ± 20%; p < .01; d = 0.87 ± 0.40). Different sources of afferent information underpinned decision-making during SS. The extended durations of recovery during SS resulted in a reduced time ≥90% HRmax but enhanced time ≥105% MAS, compared with ER exercise. Differences in the afferent cue utilisation of participants likely explain the large levels of inter-individual variability observed.The authors wish to thank Oriam: Scotland’s National Performance Centre who provided funding to support a Masters studentship for Gary McEwan.https://doi.org/10.1080/17461391.2018.147281118pubpub

Intra-session and inter-day reliability of the Myon 320 electromyography system during sub-maximal contractions

Electromyography systems are widely used within the field of scientific and clinical practices. The reliability of these systems are paramount when conducting research. The reliability of Myon 320 Surface Electromyography System is yet to be determined. This study aims to determine the intra-session and inter-day reliability of the Myon 320 Surface Electromyography System. Muscle activity from fifteen participants was measured at the anterior deltoid muscle during a bilateral front raise exercise, the vastus lateralis muscle during a squat exercise and the extensor carpi radialis brevis (ECRB) muscle during an isometric handgrip task. Intra-session and inter-day reliability was calculated by intraclass correlation coefficient, standard error of measurement and coefficient of variation (CV). The normalized root mean squared (RMS) surface electromyographic signals produced good intra-session and inter-day testing intraclass correlation coefficient values (range: 0.63-0.97) together with low standard error of measurement (range: 1.49-2.32) and CV (range: 95% Confidence Interval = 0.36-12.71) measures for the dynamic-and-isometric contractions. The findings indicate that the Myon 320 Surface Electromyography System produces good to fair reliability when examining intra-session and inter-day reliability. Findings of the study provide evidence of the reliability of electromyography between trials which is essential during clinical testing.</p