An experiment conducted by scientists from Malaysia demonstrated that exposure to the scent of dark chocolate contributes to increased endurance during strength exercises. Participants exposed to this aroma were able to perform more repetitions and sets on a leg extension machine compared to those who used milk chocolate or water. Furthermore, the subjective assessment of physical exertion remained the same regardless of the olfactory stimulus used.
Strength exercises are fundamental to athletic preparation, but their effectiveness can decrease due to calorie deficit and hunger. Recent scientific studies indicate that feelings of hunger can negatively affect both strength training and endurance training, even if the body's overall energy balance remains positive. Consequently, influencing appetite without changing actual energy intake can be seen as a way to overcome psychological barriers during intense sessions.
Olfaction stands out among external factors regulating appetite due to its close connection with the limbic and hypothalamic areas of the brain, allowing it to link scent perception with emotional responses and appetite control. Food-associated aromas can stimulate saliva production, gastric secretion, and food motivation. At the same time, other smells can suppress the desire to eat and induce a feeling of satiety. Nevertheless, little is known about how such scents directly affect physical performance.
A group of researchers led by Mohammed Nashruddin bin Naharudin from the University of Malaysia studied whether controlled olfactory stimulation could influence the intensity of physical exercise by altering appetite. The study included 23 healthy men with an average age of 23.4 years who regularly attended the gym at least twice a week. Before the workout, participants were asked to smell one of three aromas: melted dark chocolate with 90% cocoa content, milk chocolate with 60% cocoa content, or a control sample of distilled water. Propylene glycol was present in all tested samples.
Hunger and scent appeal were assessed using a 100-point visual analog scale, while perceived physical exertion was measured using the Borg scale. Afterward, participants performed weighted leg extension exercises, recording the maximum number of repetitions in each set and the total number of sets. Athletes visited the laboratory five times, with an interval of no less than four days. Each study involved two consecutive stages: assessing hunger and scent pleasantness, followed by performing the exercise and rating the perceived load when using one olfactory stimulus.
Preliminary analysis showed that the scent of dark chocolate significantly reduced levels of hunger and appetite. Meanwhile, milk chocolate received a high rating on the pleasantness scale. Moreover, it was found that the dark chocolate scent correlated with an average increase of 18 repetitions in a single leg extension set, whereas the milk chocolate scent increased this number by nine compared to the control group (p < 0.001 for both scents). Additionally, dark chocolate allowed for one extra set compared to milk chocolate and the control (p < 0.001).
It is important to note that the subjective feeling of physical exertion did not show differences depending on the scents, although a gradual increase in load was observed in each group. Thus, the scent of dark chocolate enabled a greater volume of work to be performed while maintaining the same perceived exertion rating. The scientists hypothesize that this effect is related to the suppression of hunger, since participants started the workout in a state of hunger. More extensive and fundamental scientific research is necessary for final confirmation and detailed description of the identified relationships.
