Cherie D. Pettitt

A Theoretical Method of Using Heart Rate to Estimate Energy Expenditure during Exercise

The American College of Sports Medicine advocates prescribing aerobic exercise intensities based upon target heart rate (THR); however, it advocates estimating oxygen uptake (V̇O2) using metabolic equations Derivations from metabolic equations presume metabolic responses for a given intensity and volume of exercise is exact for each athlete Conversely HR enables the coach to better estimate intensity and energy expenditure relative to an individual athletes aerobic capacity. To develop estimates of V̇O2 and subsequent energy expenditure during exercise at THR, the coach must have actual or estimated rest and maximal HR and V̇O2 values, respectively. This methodological paper describes step-by-step procedures for calculating energy expenditure during exercise at a given THR. Procedures for estimating rest and maximal HR and V̇O2 values are provided to enable the coach an immediate means of implementing this technique into their practice. Quantification of energy expenditure aids the coach in monitoring individualized training responses and developing nutritional plans with input from a dietician

Influence of elbow angle on the reliability and validity of bioelectrical impedance analysis

Hand-to-hand bioelectrical impedance (HH BIA) is a low-cost method to estimate percent body fat (%BF). The BIA method is consistently reliable, but questions on validity remain. We have observed anecdotally that elbow position can render consistently different measures of %BF while using HH BIA, thus leading to the question: Does elbow angle infl uence the validity of measures derived using HH BIA? The purpose of this study was to assess the effect of elbow position (i.e., IN=fl exed to 90° versus OUT=fully extended) on the reliability of HH BIA on 44 male and 24 female healthy adults (age=21±2 yrs, BMI=23±3). An additional aim was to assess the validity of the HH BIA %BF on a subset of subjects (n=12) using air displacement plethysmography (BOD POD®) as the criterion measure. The IN position was ~4%BF lower than the OUT position for HH BIA (p=0.05, effect size=0.67). Measures of %BF for both trials for the IN [intraclass correlation coeffi cient (ICC)=0.99, coeffi cient of variation (CV)=2.99%] and OUT (ICC=0.99, CV=1.48%) conditions were highly reliable. On the subsample, the OUT (18.3±6.7 %BF) position exceeded both the IN (14.5±7.4 %BF) and the BOD POD® (16.1±7.8 %BF) measures (p<0.05); however, IN and BOD POD® measures of %BF did not differ (p=0.21). These fi ndings support that HH BIA is a reliable measure at both elbow positions; however, %BF estimations vary considerably (~4%) with respect to the criterion measure depending on elbow position. The OUT position was found to overestimate criteria %BF. Further research may reveal an optimum elbow angle position for HH BIA estimates of %BF. Research Article