Academic journal article Journal of Physical Education and Sport

Maximal Oxygen Consumption in College Students Is Reliable Following Four Consecutive Trials

Academic journal article Journal of Physical Education and Sport

Maximal Oxygen Consumption in College Students Is Reliable Following Four Consecutive Trials

Article excerpt

Introduction

Graded exercise tests are commonly used to determine maximal aerobic power (i.e., maximal oxygen consumption [VO2max]). The VO2max is used as a physiological index for general cardiovascular health and is also used for monitoring training among athletes (Cooper, Baker, Tong, Roberts, & Hanford, 2005). This parameter is defined as the highest velocity an individual can use O2 during exercise (Akkerman, Brussel, Hulzebos, Vanhees, Helders, & Takken, 2010). Theoretically, the VO2max is reached when there is a plateau in spite of a change in workload (Akkerman et al., 2010).

The criteria used to stop a test and to determine VO2max is controversial. Some authors suggest new criteria, recommendations or methodologies (Midgley & Carrol, 2009, Midgley, McNaughton, Polman, & Marchant, 2007); however, no single consensus exist at this time. Howley, Bassett and Welch (1995), reviewed criteria to define VO2max and concluded that "the plateau in the oxygen consumption with an increased workload is the main criteria to achieve VO2max" (p. 1292).

Midgley, Carroll, Marchant, McNaughton and Siegler (2009), suggested that when the VO2 plateau is not evident, then secondary criteria must be used when participant has given a maximal effort. Two secondary criteria commonly used are the respiratory exchange ratio (RER) and heart rate (HR) (Midgley et al., 2009). For instance, Miller, Dougherty, Green and Crouse (2007), used a combination of these criteria to determine VO2max. Participants had to meet at least two out of three possible criteria: a) a plateau in the oxygen consumption with an increased workload; b) to reach the age-predicted maximal HR (HRmax); and/or c) RER ≥ 1.15. Similarly, Chia and Aziz (2008), determined VO2max when participants reached an RER ≥ 1.05; 95% HRmax, and/or the participant reached exhaustion. Based on the previous studies, it is evident that some criteria used to determine VO2max converge and other does not.

Treadmill protocols are commonly used to determine VO2max because large muscle mass are involved during the tests. The Bruce protocol has been extensively used and is considered a standard test (Miller et al., 2007). VO2max can be obtained with an indirect calorimetry system along with this protocol, which consists of 8 stages of 3 min of duration. Treadmill speed and incline grade are also part of the stages of this protocol. The Bruce protocol has been used from pediatric to elderly populations (Zijp, Berg, Willensen, Stam, Tibboel, & Ijsselstijn, 2009; Fielding, Frontera, Hughes, Fisher, & Evans, 1997); however, reliability studies are lacking. Reliability allows researchers to repeatability or consistency of values derived from a test, essay or measurement among the same individuals (Hopkins, 2000).

Other reports have estimated reliability of a treadmill-determined VO2max. For instance, Amorim, Byrne and Hills (2009), studies female children, who performed three tests, two of them the same day separated by a7 h resting period. The authors did not find significant mean differences in the VO2max between tests, concluding that treadmill-measured VO2max was stable and reproducible (i.e., reliable). The Bruce protocol has also been under scrutiny. Fielding et al. (1997), measured adult women who performed five graded exercise tests on a treadmill using the Bruce protocol. However, a longer resting period (at least 7 days) was given to the participants. The authors reported reliable VO2max values between trials.

Protocols using the animal model are also found in the literature. Evans and Rose (1998), determined VO2max in horses in three treadmill tests, with no less than 24 h resting period between trials. The researchers also reported reliable VO2max values between trials. Similarly, Copp, Davis, Poole and Musch (2009), used the rat model in five treadmill tests. For this study, animals were given 9 to 10 days rest between trials and results indicated non-significant differences in VO2max between trials. …

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