English to Spanish Medical Nutrition protein supplements

Estoy traduciendo un texto sobre el uso de suplementos proteicos. No entiendo a qué se refiere "Benefit beliefs"

Contexto:

Benefit beliefs about protein supplements: A comparative study of users and non-users

Abstract

"The consumption of protein supplements among leisure time exercisers is growing. The present study aims to identify factors that motivate protein supplement consumption by comparing users' and nonusers' underlying benefit beliefs about protein supplement. The study is based on an online survey of 813 Swiss adults (376 users of protein supplements and 437 non-users). Participants answered questions related to their benefit beliefs regarding protein supplement, their protein supplements consumption frequency, their activity level (GPAQ), and their reasons for taking protein supplement. In women, the most commonly cited reasons were to increase muscles (57.3%) and to regulate their weight (48.6%); and in men to increase muscles (83.7%) and to promote regeneration (53.7%). Furthermore, a principal component analysis revealed four benefit belief factors: (a) restore nutrients/avoid weakness; (b)fitness promotion; (c) health/well-being; (d) muscle modulation/competitive performance".

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