Ray, C. A., Cureton, K. J., & Ouzts, H. G. (1990). Postural specificity of cardiovascular adaptations to exercise training. Journal of Applied Physiology, 69, 2202-2208.

This investigation was designed to answer two questions:

1. Are cardiovascular adaptations to supine cycling the same as those obtained from the same frequency, duration, and relative intensity of upright cycling?
2. To what extent do cardiovascular adaptations obtained from supine cycling transfer to upright cycling and vice versa?

Sedentary men (ages 18-33) were divided into two groups (N = 8). Training consisted of high-intensity interval and prolonged continuous cycling in supine or upright postures 4 days/wk, 40 min/day, for 8 wk. Seven other men served as non-exercising controls. Both specifically trained groups were tested in the two postures.

In the supine group, VO2max increased 22.9% in the supine position and 16.1% in the upright position. In the upright group, VO2max increased 6.0% in the supine posture and 14.6% in the upright position. No changes occurred in control Ss.

When performing submaximal work in the supine posture, the supine-trained group increased end-diastolic volume (21%), stroke volume (22%), and decreased heart rate, blood pressure, and systematic vascular resistance. By contrast, the upright-trained group only displayed a significant decrease in blood pressure.

When performing submaximal work in the upright posture, a significant decrease in blood pressure occurred in the supine group, but significant increases in end-diastolic volume (17%) and stroke volume (18%) and decreases in blood pressure and systematic vascular resistance were displayed by the upright-trained group.

Blood volume increased significantly in the upright-trained group but not in the supine-trained group.

No changes in volume of myocardial contractility, ejection fraction, and systolic blood pressure-to-end systolic volume ratio were observed in either posture in either trained group. No significant metabolic changes occurred in the control group.

These results indicate that changes due to training were posture specific and did not generalize (transfer or cross-train) to the other posture. Neither form of posture training elicited cardiovascular adaptations at rest or during exercise in the posture not used for training. The magnitude of cardiovascular changes to training in the two groups was similar.

Implication. The extreme specificity of cardiovascular training was exhibited in this study. Only the postural position differed between the two groups with the nature of the work and activity being controlled and similar. That one variable alone was sufficient to cause specific and non-generalized training effects.

It is unreasonable to assert that cardiovascular training effects in one activity in one posture (e.g., upright running) would not transfer to another activity in a different posture (e.g., supine swimming). These results indicate that advocating "cross-training" effects between different activities and/or postures is invalid.

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