Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Has files: YesSubject: search.filters.subject.randomised cross-over trial

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    The effect of creatine monohydrate loading on cognitive performance, mood, sleepiness, and perceived workload following sleep restriction : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand
    (Massey University, 2023) Janvresse, Juliette Victoire Constance
    Background: Sleep restriction (SR; i.e. not getting enough sleep per 24 hours for one or multiple nights) impairs cognitive performance and mood, which can compromise capability and safety. SR-related performance deficits may be underpinned by disruptions to brain energy metabolism. Sleep loss appears to reduce brain phosphorylcreatine (PCr; also called creatine phosphate and phosphocreatine), which supports the regeneration of adenosine triphosphate (ATP) from adenosine diphosphate (ADP). Since creatine supplementation increases tissue PCr, including in the brain, it may mitigate possible SR-related cognitive impairments. Aim: To assess the effect of a 7-day creatine monohydrate (CrM) loading protocol on cognitive performance, mood, subjective sleepiness, and perceived workload following one night of SR (3 hours time-in-bed; TIB). Methods: A double-blinded, randomised, placebo-controlled cross-over trial was conducted with 7 healthy participants (3 men and 4 women); age, 28.0 ± 4.6 years (range, 22-35 years). Participants ingested 20 g∙dayˉ¹ of CrM or placebo (i.e. tapioca) divided into 4 equal 5 g doses for 7 days followed by a single SR night (3 hours TIB). Cognitive performance (10-minute Psychomotor Vigilance Task; PVT), mood (fatigue and vigour), subjective sleepiness, and perceived workload were measured following ~8 hours of sleep prior to creatine supplementation and following the creatine loading protocol and SR. A minimum of a 5-week wash-out period separated the two trial arms. Linear mixed effects models were employed to analyse data. Results: SR slowed mean reciprocal reaction time (p = 0.01) and mean 10% fastest reaction time (p = 0.02), increased fatigue (p = 0.004), subjective sleepiness (p = 0.009), workload (p = 0.02), and reduced vigour (p <0.001); however, it did not alter the number of lapses (p = 0.60) and mean 10% slowest reaction time (p = 0.60). CrM loading had no effect on cognitive performance, mood, subjective sleepiness, or workload. Conclusion: A single night of SR (3 hours TIB) negatively affected aspects of PVT performance, mood, subjective sleepiness, and perceived workload; however, CrM loading (20 g∙dayˉ¹ for 7 days) did not appear to mitigate the effects of SR.
  • Thumbnail Image
    Item
    The effect of a two-week ketogenic diet, versus a carbohydrate-based diet, on cognitive performance, mood and subjective sleepiness during 36 hours of extended wakefulness in military personnel : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand
    (Massey University, 2022) Henderson, Lydia Rose
    Background: Sleep deprivation (SD) compromises cognitive performance of military personnel, jeopardising operational performance and safety. Since SD-related performance deficits coincide with decreased glucose metabolism in associated brain regions, the ketogenic diet (KD) may mitigate cognitive impairments by providing an alternative fuel source (i.e. ketone bodies [KB]). Aim: To investigate the effect of a 2-week KD compared with a carbohydrate (CHO)-based diet on cognitive function, mood and sleepiness during 36 hours of extended wakefulness. Methods: A randomised, cross-over trial was conducted with 7 military personnel (range, 26- 45 years). Participants ingested a KD (~25 g·day⁻¹ CHO) or CHO-based diet (~285 g·day⁻¹ CHO) for 14 days, immediately followed by 36 hours of wakefulness and separated by a 12-day washout period. Cognitive performance (5-minute Psychomotor Vigilance Task; PVT), mood (fatigue and vigour), subjective sleepiness, and capillary blood glucose and D-β-hydroxybutyrate (D-βHB) concentrations were measured every 2 hours (1, 3 and 5 hours after each meal). Linear mixed models tested the effect of diet, period (6 x 6-hourly bins), test time (1-3) within periods, and their interactions. Results: D-βHB was higher (+0.75 to +1.45 mM; p < 0.001) and glucose was lower (-0.26 to -1.16 mM; p < 0.01) in the KD compared with the CHO-based diet. The KD improved performance for all PVT variables (number of lapses, mean reciprocal reaction time [RRT], slowest 10% RT and fastest 10% RT) (p < 0.05), mood (p = 0.001), and sleepiness (p < 0.001) compared with the CHO-based diet; however, there were no interactions with period or test. Number of lapses and subjective sleepiness increased, and mood, mean RRT and slowest 10% RT deteriorated during the 36 hours of extended wakefulness independent of diet (all p < 0.01). Circadian effects were also observed for fastest 10% RT, mood and sleepiness independent of diet (all p < 0.01). Conclusion: The KD appeared to improve cognitive performance, mood and sleepiness during 36 hours of extended wakefulness compared with the CHO-based diet. This suggests the KD could be considered for military operations when sleep deprivation is anticipated.