Below is a table from a study by Ballor et al. (1990) in which the authors examined the potential differences between Moderate Intensity and Vigorous/High-Intensity Exercise Training on weight loss and body composition changes. This study is unique, in that both training interventions were matched on total energy expenditure to isolate the independent effect of "intensity." please explain what the table is showing specifically related to body mass, fat mass, fat-free mass, and percent fat. Please be specific, and cite relevant data when necessary.

TABLE I Physical characteristics of the subjects* Groupt Pretest Posttest Difference Body mass Fat-free mass High 79.1 8.4 73.1 8.2 -6.0 1.98 Low 78.2 6.4 72.6 6.8 -5.6 1.88 High 50.3 3.6 48.8 3.8 -1.4 1.1 Low 48.8 3.5 47.9 3.2 -0.9 1.28 Fat mass High 28.8 6.6 24.3 7.2 -4.5 2.1 Low 29.4 4.3 24.7 4.5 -4.7 1.38 Percent fat High 36.1 5.0 32.7 7.0 -3.4 2.68 Low 37.5 3.2 33.8 3.5 -3.7 1.48 Sum of five skinfold-thickness measurements (mm) High 135.4 43.6 115.9 44.7 -19.5 12.58 Low 151.9 38.2 125.8 35.1 -26.1 15.28 Peak VO (L/min) High 2.3 0.4 2.7 0.5 0.4 0.4|| Low 2.3 0.2 2.4 0.3 0.1 0.2|| Peak VO (mL. kg'. min) High 29.5 4.9 37.1 8.3 7.6 5.18 Low 29.6 2.9 33.3 4.5 Peak heart rate (beats/min) High 181.3 6.21 179.6 8.11 Low 187.5 6.21 188.5 7.21 3.8 3.0|| -1.7 5.1 1.1 4.5 *X SD. High group, n=14; low group, n = 13. Posttest value minus pretest value. Pretest significantly different from posttest (within groups, ie, high pretest different from high posttest), p