Publication Date


Document Type


First Advisor

Sebastião, Emerson

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Kinesiology and Physical Education (KNPE)


Obesity can dramatically and negatively affect many aspects of normal physiological functioning. Obesity is defined as abnormal or excessive body fat accumulation that presents a risk to health. Body mass index (BMI) is a widely used approach to quantify body fat in large group settings; however, this method has significant shortcomings with accuracy and estimation. More direct measures such as bioelectrical impedance analysis (BIA) can provide a more reliable and accurate assessment of body fat mass and, therefore reduce the shortcomings of BMI when assessing possible associations with health- and performance-related variables. A plethora of research studies has been conducted on variables using BMI or other surrogate methods to estimate body fatness (i.e. waist-to-hip ratio); however, few have observed body fat percentage (%BF) as the independent variable and how particular physiological and fitness markers are affected. Physiological variables included resting heart rate (RHR), heart rate variability (HRV), and heart rate recovery (HRR). The fitness variables included exercise tolerance (TTE), and maximal oxygen uptake (VO2Max). PURPOSE: The present study investigated possible associations between %BF and various physiological (RHR, HRV & RHR) and fitness markers (TTE & VO2Max) in physically inactive adults. METHODS: Seventy-five total participants were recruited for the study. Of the total recruited for the study 36 were excluded for various reasons. Thus, the final analytical sample comprised 39 apparently healthy adults of both genders who were identified as physically inactive. Participants undertook a collection of physiological and fitness measures that were conducted in a single visit to the Exercise Physiology Laboratory and took an average of 2h per participant. Basic anthropometric data was gathered prior to body composition assessments, which was measured using the InBody 520. HRV (ms) and RHR (bpm) were measured using a Polar Bluetooth heart rate monitor and a valid cell phone application (i.e., EliteHRV). Exercise tolerance was measured using a Woodway treadmill and the Bruce graded exercise protocol. The referred protocol takes into consideration both speed and grade and allowed for the collection of information pertaining to TTE and heart rate (HR).. HR was recorded after 1 and 2 minutes and was used to determine HRR. All performance variables were used in an estimation equation for VO2Max. To accomplish the purpose of the study, data were analyzed using Pearson r and Spearman rho correlation analysis, and correlation coefficients were interpreted as small (0.1), moderate (0.3), and large (0.5). Significance was set at P < 0.05. RESULTS: There was a small negative correlation observed between %BF and HRV, although not statistically significant (P = 0.37) (r = -0.15). Similar small negative correlation was seen in HRR1 (P = 0.50), which was also not statistically significant (r = -.011). Although a large positive correlation was seen between %BF and RHR, it was not statistically significant (P = 0.76) (r = 0.05). There was a large negative correlation seen between %BF and TTE (r = -0.68) and VO2Max (r = -0.84) where both correlations were statistically significant (P = 0.00) & P = 0.00 respectively). CONCLUSION: The findings of the present study demonstrated small-to-large correlations between %BF and various physiological and fitness markers. However only correlation between %BF and TEE and VO2Max were found to be statistically significant. Therefore, these findings suggest a potential small detrimental effect of increased %BF on observed physiological (RHR, HRV & HRR) and fitness (TTE & VO2Max) variables.

Keywords: body fat percentage, exercise tolerance, BIA, body composition


60 pages




Northern Illinois University

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