Sufficient data are available to support the inclusion of upper body or combined arm-leg training in a comprehensive physical conditioning program. There is now evidence to suggest that initial fitness, as well as the intensity, frequency, and duration of training, may be important variables in determining the extent of cross-training benefits from the legs to the arms, and vice versa. Nevertheless, the limited degree of transfer of training benefits from one set of limbs to another appears to discount the practice of emphasizing leg training alone. Aerobic exercise programs for the upper body may yield significant central (Q and SV) and peripheral (a-vO2 difference) adaptations to support improvements in peak oxygen uptake (VO2peak) during arm and leg work, especially in subjects who are initially unfit, with the more dominant effects specific to the upper extremities. Finally, an arm exercise prescription that is based on the maximal heart rate derived from leg testing may result in an inappropriately high target heart rate for arm training. Workloads (kg.m.min-1) considered appropriate for leg training will generally need to be reduced by 50-60% for arm training.