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Succeeding in postgraduate study
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2 Getting to grips with critical thinking

In this section, you will be considering a written extract taken from a published article, and listening to a conversation that evaluates the extract and some related information. You will then be presented with three separate statements using different examples of writing and will have to decide which of the examples presents a more convincing argument, and explain your reasons why.

Activity 1 Getting to grips with critical thinking

Timing: Allow approximately 60 minutes

The extract below is taken from the article by Chase, Sui and Blair (2008a), published in the International Journal of Aquatic Research and Education. First read this extract and then listen to the audio recording that follows.

Swimming, water jogging, and aqua aerobics are excellent aerobic activities that might provide health benefits to the general population, as well as patients with chronic disease such as heart failure (Schmid et al., 2007). Aquatic exercises might be preferred over other forms of aerobic activity for people who have arthritis, diabetes, disabilities, or excess weight (Lin, Davey, and Cochrane, 2004). Most studies on physical activity and health have included aerobic activities such as walking, jogging, and aerobics classes, but few such studies have included swimming as an exposure. It is important to understand how or if swimming and other types of physical activity are related and how they relate to health outcomes. Therefore, the goal of this study was to evaluate the characteristics of participants in the Aerobics Center Longitudinal Study (ACLS) and to compare the health habits and physiological characteristics of swimmers, runners, walkers, and sedentary women and men. Our principal purpose was to evaluate whether regular swimming is comparable to other aerobic activities in terms of beneficial health outcomes.

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Session 8 Activity 1 audio
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We have included the supporting information explored in the audio below, to review should you wish. (You can listen to the entire audio first and review the supporting information afterwards, or you can pause the audio at specific points, review the supporting information, and return to the recording again, if you prefer. Please choose whichever option suits you best.)

Supporting information

  • In the opening sentence of their discussion (Chase, Sui and Blair 2008a, p. 158), the authors state:

    ‘The principal findings of this report are that all types of physical activity have similar health benefits compared with a sedentary lifestyle. Swimming and running had the same health benefits even though there were a few differences between swimmers and runners.’

  • Towards the end of the discussion (p. 159), they state:

    ‘The principal strength of this study is the large population that we observed and the extensive database of the ACLS, which has been developed over more than 30 years.’

  • At the end of the discussion (p. 159), they state:

    ‘The study also has limitations. Results must be generalised with caution because the population includes few members of minority groups and comes from relatively high socio-economic strata. Because this was a cross-sectional study, we cannot make causal inference from the results.’

  • In their conclusion (p. 159), they state:

    ‘In conclusion, swimming might provide a healthful alternative to traditional modes of exercise… for the general population, as well as for patients suffering from chronic diseases… Our results show that swimming appears to have health benefits similar to those of running and generally was more beneficial than walking or a sedentary lifestyle.’

  • The authors published a second article in 2008, which appeared in the next issue of the same journal (Chase, Sui and Blair, 2008b). In the introduction to their second article (p. 214) the authors referred to their previous study, stating that:

    ‘Swimming, water jogging, and aqua aerobics are lifetime physical activities for many people. We have previously shown that swimming provides health benefits comparable to those from walking and running.’ (Chase, Sui and Blair, 2008b)

  • The acknowledgements section for both articles noted that the research ‘was supported by the National Swimming Pool Foundation and National Institutes of Health Grants’. No financial disclosures were declared.
  • A search for both articles on Google Scholar (October 2016) indicated that their first publication had been cited 12 times, and their second a total of 17 times.
  • Their first article had been cited by a systematic review and meta-analysis on the ‘Health benefits of different sport disciplines for adults…’, published by Oja et al. (2015) in the British Journal of Sports Medicine. The abstract makes it clear that the aim was ‘to assess the quality and strength of evidence for the health benefits of specific sports disciplines’. It goes on to state that moderately strong and conditional evidence supported the health benefits of running and football, but that ‘Evidence for health benefits of other sport disciplines was either inconclusive or tenuous. The evidence base for the health benefits of specific sports disciplines is generally compromised by weak study design and quality.’

If you wish to read further, you can access the full texts of the articles by Chase, Sui and Blair (open access), and the abstract of the article by Oja et al. (2015) via the links provided below:


The following questions should prompt you to reflect further on this activity:

  • Is the declaration that ‘Swimming, water jogging, and aqua aerobics are excellent aerobic activities’ an unsupported assertion in your view?
  • In the Extract (introduction) they state that their participants were from the ‘Aerobics Center Longitudinal Study (ACLS)’ (spanning over three decades), but it emerges from reading their Discussion that the study they are actually reporting on is a cross-sectional study, and that the authors ‘cannot make causal inference from the results’ because of this. Have they been clear about communicating their study design and considering other limitations?
  • Could the fact that the research was partly sponsored by the National Swimming Pool Association have influenced the way the findings have been communicated? Would this affect your own judgement in any way?