The primary aim of this dissertation was to examine the effects of creatine (Cr) supplementation on exercise performance, body mass, muscle phosphocreatine (PCr), and blood Cr in older men. The effect of acute (20 g of Cr d −1 for 5 d, preliminary study) and longer term (20 g of Cr d −1 for 10 d followed by 4 g of Cr d−1 for 20 d, Study I) Cr supplementation on isokinetic leg fatigue, maximal isometric force (MIF), and body mass was examined in healthy older men (60–82 yr) over two studies. In both the preliminary study and Study I there was a small improvement on the isokinetic leg fatigue test, but this did not achieve statistical significance. There was no effect of the Cr supplement on MIF. In the preliminary study there was a small (0.5 kg) increase in body mass in the Cr group after supplementation, but in Study I this difference was not statistically significant between groups. In Study II, the effects of Cr supplementation on muscle PCr, blood Cr, urine Cr, and urine creatinine (Cn) were assessed in eight young (20–32 yrs) and seven old (63–83 yrs) male subjects who ingested Cr (20 g d −1) for 5 days. Plasma Cr, following a 5 gram oral Cr bolus, increased, with no difference in the response between groups. Urine Cr, assessed pre and on five days of supplementation, increased, with no difference between groups. Urine Cn did not change as a result of Cr supplementation. Muscle PCr, assessed pre- and post-supplementation increased significantly more in the young subjects. Data from the preliminary study and Study I suggest that acute and longer term oral Cr supplementation does not affect MIF and only produces small increases in body mass and performance on an isokinetic leg fatigue test in men over the age of 60. The smaller increase in muscle PCr in the older subjects in Study II may explain the lack of a significant ergogenic effect of Cr in this population.

Idéen att katters spinnande kan emotionellt och fysiologiskt påverka oss verkar resonera med många, och sprids kraftigt av media. Påståendet saknar dock vetenskaplig grund. Syftet med denna studie var att studera spinnandets effekt på människor, genom att undersöka om spinnande ger upphov till någon emotionell respons och/eller pulssänkande effekt. Studien använde en experimentell design och utgick från en dimensionell emotionsteori med skalor över valens och arousal. Deltagarna blev presenterade med isolerade auditiva stimuli innehållandes olika djurläten och ombads sedan notera sin puls och emotionstillstånd. Självskattningsformuläret SAM (The Self-Assessment Manikin) användes som metod för att mäta emotionella förändringar. Resultatet visade att katters spinnljud har en signifikant arousalsänkande effekt hos människor. Ingen signifikant påverkan på valens eller puls hittades. Studien belyser behovet av vidare forskning inom ämnet för att ytterligare förstå och kartlägga spinnandets effekt på människor. / The idea that cats’ purring can affect us emotionally and physiologically seems to resonate with many people and is widely spread by media. However, the claim lacks scientific backing. The purpose of this study was to investigate the effect of purring on people by examining whether purring gives rise to any emotional response and/or pulse-lowering effect. The study used an experimental design and was based on a dimensional emotion theory with scales of valence and arousal. Participants were presented with isolated auditory stimulus containing various animal sounds and was then asked to note their heart rate and emotional state. The self-assessment form SAM (The Self-Assessment Manikin) was used to measure emotional changes. The results showed that the purring sound of cats has a significant arousal-reducing effect in humans. No significant effect on valence or heart rate was found. The study highlights the need for further research on the subject to deepen our understanding of the effect that purring has on humans.