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NEW, VALID OXYGEN CONSUMPTION EQUATION UP TO AN INCLINE OF 40% FOR THE AVERAGE INDIVIDUAL

Abstract

N. Preston, A. Gidley, D.E. Lankford FACSM

Brigham Young University-Idaho, Rexburg, ID

Equations from the literature that predict oxygen consumption (VO2) are often simplistically linear or unnecessarily exponential, they are often extrapolated to higher incline values without data to support the equation, and they are often calculated using only a few subjects who are usually highly trained or even competitive athletes. PURPOSE: To determine a simple oxygen consumption equation with data collected at higher inclines, with otherwise healthy, non-trained individuals. METHOD: 45 subjects (34 males: age 25.09 ± 4.17 years, height 180.30 ± 7.86 cm, weight 81.55 ± 16.9 kg; 11 females: age 25.4 ± 5.52 years, height 165.86 ± 3.29, weight 65.44 ± 10.35) performed three separate trials at 1, 2, and 3 mph at 9 inclines: 0, 5, 10, 15, 20, 25, 30, 35, and 40% grade over three visits. For the inclines at 3 mph, each stage consisted of 5 minutes while 1 and 2 mph stages were 4 minutes long. For each stage, VO2was averaged over the last 2 minutes. Each subject fasted at least four hours prior to a testing day and resting metabolic rate (RMR) was collected at the beginning of each visit. Body composition was determined via plethysmography prior to the first stage collected. A multiple linear regression was determined using speed, incline, heart rate, and weight. The equation was then validated with data collected for each incline, speed stage from a separate group of 18 subjects (age 23.52 ± 1.69 years, height 169.31 ± 10.72 cm, weight 67.76 ± 12.6 kg). A t-test was used to determine significance between the collected and predicted VO2 of the validation group. RESULTS: As expected, VO2 increased with incline within a speed and between speeds: 3mph > 2mph > 1mph. The calculated prediction equation: VO2 = (speed (m/s) * 15.839) + (incline (degrees)*1.176) + (heart rate(bpm) * 0.122) + (weight(kg) * 0.048) -11.112 (R2= 0.84). Each variable significantly contributed to the equation (p<0.01). The estimated VO2 (26.02 ± 13.61) was not significantly different than the collected VO2(21.88 ± 14.06, p = 0.35) of the validation group. CONCLUSION: We found a relatively simple linear regression equation which closely estimates VO2 which is valid at very high inclines and can be used with an otherwise healthy individual.

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