The accuracy of predicting treadmill VO2max for adults with mental retardation, with and without Down's syndrome, using ACSM gender- and activity-specific regression equations.

Abstract

The purpose of this study was to examine the validity of the American College of Sports Medicine's (ACSM) prediction equations for calculating peak oxygen consumption (VO2max) in young adults with mental retardation. A total of 32 subjects with mental retardation participated in this study: 15 young adults with Down's syndrome (DS) and 17 non-DS young adults (NDS). Subjects were matched for age, gender and intelligence quotient (IQ). Subjects were given a standard treadmill-graded exercise test to determine peak heart rate (HR) and peak oxygen consumption (VO2max). Subjects were connected to a metabolic cart during the test. Peak VO2 was predicted using ACSM's prediction equations where predicted VO2max is: men, 57.8-0.445 (age); and women, 42.3-0.356 (age). Statistical significance between groups was determined using a two-tail t-test, with alpha set a priori at 0.05. The DS group had a significantly (P = 0.0003) lower peak HR (DS 155.90 +/- 12.12 vs NDS 175.38 +/- 9.87) and per cent HR achieved (P = 0.0007) (DS 80.26 +/- 6.76 vs NDS 89.39 +/- 4.46) as compared to the NDS group. Differences were also found between groups with respect to peak oxygen consumption. The DS had a significantly (P = 0.006) lower peak oxygen uptake (ml kg-1 min-1) as compared to the NDS group (23.68 +/- 4.01 vs 31.00 +/- 7.11, respectively). Significant differences (P = 0.007) were accordingly observed with respect to per cent predicted oxygen uptake achieved (DS 55.22 +/- 10.61 vs NDS 73.27 +/- 19.15). A nearly two-fold difference (P = 0.01) was observed with respect to the functional aerobic impairment between the DS (44.79 +/- 10.61) and NDS (28.29 +/- 18.63) groups, further illustrating the impaired peak cardiovascular capacities of both groups. The results of this study indicated that use of the ACSM gender and activity specific prediction equations in young adults with mental retardation (DS and NDS), peak VO2 is significantly over-predicted (83.9 and 39.2%, respectively). Therefore, peak oxygen consumption and derived exercise prescriptions must be based on actual measurements, rather than via ACSM prediction equations. Otherwise, training intensities may be over-predicted and impose possible health risks.