Impact of Acute Resistance Exercise on Taste Perception and Appetite Response to Plant Protein in Resistance Trained Adults

Some evidence suggests that taste perception might be modulated by physical exercise, with differences observed after aerobic exercise (DOI:10.1093/chemse/23.4.417) and with habitual exercise (DOI:10.3390/nu11010155). However, the effects of resistance exercise on taste perception has not been studied. This knowledge is important as it may impact the acceptability of foods consumed after exercise.

While plant-protein supplement powders are gaining increased popularity, their palatability and, thereby, acceptability may be a shortcoming. This randomised crossover trial aims to investigate (1) the taste perception and acceptability of plant protein supplement powders and (2) whether resistance exercise modulates taste perception and appetite responses to plant protein.

Phase 1 (part 1): A randomised crossover trial, involving 15-20 adult men (aged 18-40 years old). Two conditions (resistance exercise or rest) will be undertaken in randomised order.

Participants will be required to attend three tests visits. The first visit will last approximately 2 hours and involves signing informed consent, body composition assessment (BodPod), strength tests (3-Repetition Maximum) and completion of questionnaires.

The second and third visits are the experimental test visits (exercise or rest) and will last approximately 4 hours each. Individuals will arrive at the laboratory two hours after consuming a standardized breakfast.

Participants will be provided with eight food-grade samples and asked to complete a battery of questionnaires to evaluate taste perception and liking (visual analogue scales (VAS), generalised labelled magnitude scale (gLMS), 9-point Likert scale). The eight samples are: (1) sucrose (2) umami (3) soy protein (4) pea protein (5) hemp protein (6) brown rice (7) whey protein and (8) apple juice. Each sample will be served as a 20-mL-solution. Except for sucrose and umami (in water), the protein-based samples will be served in low sugar apple juice. Subjects will taste the samples in a "sip-and-spit" manner. Each solution will be designated by a 3-digit number and they will be provided in a randomized order.

Participants will then undergo approximately 1 hour of rest (control) or resistance exercise conditions, after which they will repeat an identical tasting session of the 8 samples.

The resistance exercise will be composed of the 4 exercises, that will be performed at a high-to-medium intensity (75% of the maximum calculated), intensity represented by 10 estimated repetitions. Four sets of each exercise will be assisted by the investigator.

Phase 1 (part 2): The second part of each test visit (exercise or rest) involves the participant consuming a soy protein drink (30g soy protein powder, according to most of the manufacturer's recommendation) solubilized in 200ml low-sugar apple juice (to increase palatability). After an hour of rest, the participant will then be served an ad libitum lunch meal (pasta bake with tomato sauce and cheese, strawberry yogurt and water). Appetite will be assessed both during rest and after the lunch meal via VAS.

Saliva samples will also be collected at three time-points during the test visit to provide insight into potential mechanisms contributing to alterations in taste perception and appetite.

Phase 2: Part 1 is extended to 15-20 adult female participants (18-40 years old) to provide insight into any potential sex differences in findings. The eight samples tested are identical except brown rice protein is replaced with clear protein isolate (a form of hydrolysed pea protein).

Eligibility Criteria:
Inclusion Criteria:

* Phase 1: Adult males; Phase 2: Adult females
* Aged between 18 and 40 y.o.)
* Physically active in accordance with IPAQ
* Lifting weights, at least, once a week
* Healthy
* Non-smokers
* BMI between 18 and 30

Exclusion Criteria:

* Phase 1: Females; Phase 2: Males
* Subjects younger than 18 or older than 40 y.o.
* BMI lower than 18 and higher than 30
* Insufficiently active individuals
* Physical active individuals that do not perform a regular strength training
* Having any condition health-related that could preclude both their participation in physical testing and a bout of resistance training
* Taking medications known to impact taste and/or appetite
* Medical condition known to impact taste and/or appetite
* Medical condition linked to cognitive impairment