Date of Award
Doctor of Philosophy
Ann Swartz, Chi Cho, Christy Greenleaf, Young Cho
Eldery, High Intensity Interval Walking, Interval Training, Oxygen Consumption, VO2max
PRESCRIBING VIGOROUS INTENSITY EXERCISE TO OLDER ADULTS
The University of Wisconsin-Milwaukee, 2020
Under the Supervision of Professor Scott Strath, PhD
As the older adult segment of society grow, rates of chronic disease and poor fitness continue to climb. Physical activity (PA) and exercise are effective methods to offset incidence of disease and improve physical fitness. However, despite these known benefits, older adults exhibit low rates of PA engagement. Barriers to PA that are specific to older adults include lack of knowledge and perceived lack of time. Interventions targeting older adults and addressing these barriers by way of behavioral theory implementation are one method to increase PA and physical fitness. Assessment of physical fitness can be challenging for this group, however, as certain methods can be unsafe and are not recommended. Maximal oxygen consumption (VO2max) is a common measure of aerobic fitness and is often used to determine the effectiveness of an exercise intervention. Field tests to estimate VO2max are a practical solution to this dilemma, as they are easy to administer and do not require the participant to work to maximal effort. Still, there are limitations as to the validity and application of these tests.
For VO2max to improve, a certain training intensity threshold needs to be met. Traditional exercise recommendations involve long, continuous bouts of moderate intensity activity. This extended time commitment is a common barrier for many adults. High intensity interval training (HIT) is a protocol that was developed in response to the time constraints associated with traditional exercise. The vigorous intensity and small exercise volume (i.e. alternating between quick bursts of activity and low intensity recovery periods) allow for participants to improve health and fitness parameters to a similar or greater extent as traditional training, but with a much smaller time commitment. As many of these protocols require maximal or near maximal exertion, and sometimes involve running, a protocol more appropriate for older adults has been developed. High intensity interval walking (HIW) is a type of HIT training that has recently been developed but not studied extensively in older adults. Further, little to no work has been done to investigate the translational effects of HIT or HIW to a community-based setting.
The purpose of this dissertation was to evaluate changes in VO2max and PA levels in older adults by prescribing vigorous intensity exercise. The aims of this dissertation are twofold: 1.) to create and determine the most valid equation to predict VO2max between a series of field-based walking and stepping tests among adults age 18-79 years, and 2.) to determine if older adults’ VO2max and PA levels will increase following a theoretically guided, 4-week high intensity interval walking intervention.
A series of eight different walking (n=5) and stepping (n=3) field tests were analyzed to create the highest performing VO2max prediction equations that varied in duration and number of stages. Demographic, anthropometric, and physiological covariates (e.g. heart rate, gait speed, and step cadence) were entered into each model. Final models were then entered into a jackknife validation analysis, and percent bias and root mean square error (RMSE) were assessed. Overall, the tests accounted for ~81% of the variance (R2) of VO2max and had a RMSE of <4.5 ml.kg-1.min-1. The stepping tests outperformed the walking tests by having higher R2 and lower RMSE values. Collectively though, the difference across the tests were minimal enough that there is flexibility in selecting a test appropriate for various populations.
A 4-week HIW intervention was administered to older adults (age 60-85) to determine its effectiveness in increasing VO2max and time spent in intensities equal or greater to a normal walking speed. Theoretical constructs were implemented to improve adherence and address barriers by addressing self-efficacy for exercise (SE). VO2max did not significantly improve for either the control (CON) or intervention (HIW) group, despite 70% of the HIW group seeing an improvement. Physical activity levels did increase significantly for the HIW group from baseline to post-testing (p<0.01), yielding large effect sizes around [0.88]. Further, the changes in PA levels for the HIW group were significantly greater than those in the CON group (p<0.01), also yielding large effect sizes around [0.79]. Additionally, SE significantly improved from baseline to post-testing for the HIW group (p<0.05) but not the CON group, yielding moderate effect sizes ([0.73] and [0.59], respectively).
The findings from this dissertation support the need to continue to develop and validate field tests to most accurately predict VO2max among diverse populations. Further, this dissertation supports continued research pertaining to large-scale HIW protocols in older adult populations, as it appears to be a feasible option for improving PA and SE. Future studies should continue to examine the lasting effects of HIW interventions to see if it is an activity that individuals will continue to engage in.
Rowley, Taylor, "Prescribing Vigorous Intensity Exercise to Older Adults" (2020). Theses and Dissertations. 2417.
Available for download on Saturday, November 21, 2020