It has been suggested that the anaerobic threshold (AT) represents a minimal intensity for eliciting an exercise training adaptation. Thirteen men (age = 66 +/- 9; weight = 81 +/- 13kg) and two women (age = 58 +/- 21; weight = 70 +/- 3kg) with coronary heart disease (CHD) trained for 12 weeks to determine the effect of an exercise regimen composed of three- to six-minute intervals of alternating arm and leg cycling (cross-training) on AT. The patients cross-trained for a total of 30 minutes per session, three days per week. Maximal cycle ergometer tests with breath by breath ventilatory gas analyses were performed before and after training. Peak oxygen uptake increased by 8.9% and peak power output increased (p < .05) by 28.3%, whereas resting heart rate (HR) decreased (p < .05) by 9.6% as a result of the cross-training regimen. Cross-training did not effect a significant change in AT but HR at AT was decreased by 6.3% (p < .05). Arm and leg cross-training produced a physiological adaptation and may have reduced the HR threshold for effective exercise training.