The placebo and nocebo effects on peak minute power during incremental arm crank ergometry

This investigation aimed to explore the effects of inert sugar-free drinks described as either ‘performance enhancing’ (placebo) or ‘fatigue inducing’ (nocebo) on peak minute power (PMP;W) during incremental arm crank ergometry (ACE). Twelve healthy, non-specifically trained individuals volunteered to take part. A single-blind randomised controlled trial with repeated measures was used to assess for differences in PMP;W, oxygen uptake, heart rate (HR), minute ventilation, respiratory exchange ratio (RER) and subjective reports of local ratings of perceived exertion (LRPE) and central ratings of perceived exertion (CRPE), between three separate, but identical ACE tests. Participants were required to drink either 500 ml of a ‘sports performance’ drink (placebo), a ‘fatigue-inducing’ drink (nocebo) or water prior to exercise. The placebo caused a significant increase in PMP;W, and a significant decrease in LRPE compared to the nocebo (p=0.01; p=0.001) and water trials (p=0.01). No significant differences in PMP;W between the nocebo and water were found. However, the nocebo drink did cause a significant increase in LRPE (p=0.01). These results suggest that the time has come to broaden our understanding of the placebo and nocebo effects and their potential to impact sports performance.

The effect of carbohydrate mouth rinse on a 30-minute arm cranking performance

The aim of this study was to examine the effect of carbohydrate mouth rinse on 30-min arm cranking performance. Twelve healthy, active males (age 21.6, standard deviation (SD)=3.1 years; mass 76.2, SD=12.2 kg) volunteered in a single-blind, randomised crossover design. Firstly they completed an incremental exercise test to exhaustion (VO2max test) on an arm crank (50W for 2 min, increasing by 10W every min). During visit 2 and 3 they arm cranked for maximal distance over 30 min at a resistance equivalent to 50% of their peak power, mouth rinsing for 5 s with either 25 ml of a tasteless 6.4% maltodextrin solution (CHO) or 25 ml of water (placebo) every 6 min. A letter cancellation test was performed pre and post exercise to measure cognitive function. The result showed that cognitive function was not significantly different between trials (P=0.874). There was no significant difference in distance arm cranked between trials (P=0.164) even though 9 out of 12 participants had improved performance on the CHO trial. In conclusion, further research is needed to determine the ergogenic effect of CHO mouth rinsing on upper body exercise performance.

The placebo and nocebo effects on peak minute power during incremental arm crank ergometry

This investigation aimed to explore the effects of inert sugar-free drinks described as either ‘performance enhancing’ (placebo) or ‘fatigue inducing’ (nocebo) on peak minute power (PMP;W) during incremental arm crank ergometry (ACE). Twelve healthy, non-specifically trained individuals volunteered to take part. A single-blind randomised controlled trial with repeated measures was used to assess for differences in PMP;W, oxygen uptake, heart rate (HR), minute ventilation, respiratory exchange ratio (RER) and subjective reports of local ratings of perceived exertion (LRPE) and central ratings of perceived exertion (CRPE), between three separate, but identical ACE tests. Participants were required to drink either 500 ml of a ‘sports performance’ drink (placebo), a ‘fatigue-inducing’ drink (nocebo) or water prior to exercise. The placebo caused a significant increase in PMP;W, and a significant decrease in LRPE compared to the nocebo (p=0.01; p=0.001) and water trials (p=0.01). No significant differences in PMP;W between the nocebo and water were found. However, the nocebo drink did cause a significant increase in LRPE (p=0.01). These results suggest that the time has come to broaden our understanding of the placebo and nocebo effects and their potential to impact sports performance.

Associations of the mechanical, anthropometric and gait contributors to the knee adduction moment during paediatric gait

The knee adduction moment (KAM) during gait has been proposed as an indirect measure of dynamic knee joint loading and has been reported to be higher in obese children [1, 2]. The KAM is primarily calculated from the resultant ground reaction force (GRF) and the lever arm length, both of which can be manipulated through weight-loss or medical interventions [1]. However, there is little data on the relationships between the mechanical, anthropometric and gait contributors to the KAM during paediatric gait. The objectives of the study were to examine the associations with the first (1st) and second (2nd) peak KAM (pKAM) and: (1) centre of pressure (CoP), KAM lever arm length, vertical and mediolateral ground reaction forces (GRF) and, (2) fat mass, height, step width, foot rotation, knee rotation and walking velocity.

Modulation of pain threshold by virtual body ownership

Background Appropriate sensorimotor correlations can result in the illusion of ownership of exogenous body parts. Nevertheless, whether and how the illusion of owning a new body part affects human perception, and in particular pain detection, is still poorly investigated. Recent findings have shown that seeing one’s own body is analgesic, but it is not known whether this effect is transferable to newly embodied, but exogenous, body parts. In recent years, results from our laboratory have demonstrated that a virtual body can be felt as one’s own, provided realistic multisensory correlations. Methods The current work aimed at investigating the impact of virtual body ownership on pain threshold. An immersive virtual environment allowed a first-person perspective of a virtual body that replaced the own. Passive movement of the index finger congruent with the movement of the virtual index finger was used in the “synchronous” condition to induce ownership of the virtual arm. The pain threshold was tested by thermal stimulation under four conditions: 1) synchronous movements of the real and virtual fingers, 2) asynchronous movements, 3) seeing a virtual object instead of an arm, and 4) not seeing any limb in real world. Results Our results show that, independently of attentional and stimulus adaptation processes, the ownership of a virtual arm per se can significantly increase the thermal pain threshold. Conclusions This finding may be relevant for the development and improvement of digital solutions for rehabilitation and pain treatment.