It has been shown that strength-training regimens improve G-endurance. The mechanisms underlying such improvement are unknown. We reasoned that during repeated straining maneuvers - as during G-endurance testing - the exercise pressure-response plays a significant role in maintaining adequate arterial pressure. Also, we hypothesized that different training modalities might, by altering the muscle-metabolic response to sustained contractions, affect the exercise pressor-response. Methods: Three groups of healthy males were studied, endurance trained (E; n=17), strength trained (S; n=16) and untrained (U; n=17) individuals. The exercise pressor-response was studied during sustained (40 sec) isometric knee-extensor contractions at 50% of the maximal voluntary contraction level. Relaxed gradual onset-rate G-tolerance was established. Results: The mean arterial pressure response during isometric exercise was higher (p<0.05) in the S group ((?MAP:36±7 mmHg (=mean±SD)) than in the E group (28±8 mmHg), but similar in the S group and the U group (35±16 mmHg). G-tolerance was similar in the E (4.6±0.5 G), S (4.9±0.8 G) and U (4.6±0.8 G) groups. Conclusions: The results suggest that training modality affects the magnitude of the exercise pressor-response. However, it seems that the response is blunted by endurance training rather than improved by strength training. It thus appears unlikely that the previously observed strength-training induced improvement in G-endurance is caused by altered exercise pressor-response or increased relaxed G-tolerance.