Critique the Sampling Strategy in the Following Qualitative Research Study

Critique the sampling strategy in the following qualitative research study, adapted from Crust, Swann, Allen-Collinson, Breckon, and Weinberg (2014):
Although sport has provided an ideal context for exploring mental toughness, currently, there is little research examining how this construct might be equally applicable in exercise settings. The present qualitative research study aimed to understand and conceptualise exercise mental toughness through in-depth interviews with exercise leaders and exercise participants. Seven exercise leaders and seven exercisers were randomly selected to participate in this study. Interviews were audio-recorded, transcribed verbatim, and analysed independently by members of the research team. Key themes were agreed and member checking was used to promote trustworthiness of interpretations. Mental toughness was recognisable in exercise settings, with 10 general dimensions found to be reflective of conceptualisations derived from sport (e.g. commitment, focus). Importantly, present findings reveal how mentally tough exercisers think and behave in exercise settings.