Perceptual responses to exercise: the effect of load-awareness on physiological responses during an isometric bout.

To evaluate the effect of awareness of load on cardiovascular and metabolic responses, thirty males were compared in three different loads during upright deadlift isometric exercise, at 25%, 30% and 35% of maximal voluntary contraction for 3 min. Significant differences (P < 0.05) were found from rest to 25%, 30% and 35% for all physiological variables, heart rate (66.5+/-9.0, 104.0+/-12.0, 115.0+/-9.0, and 123.0+/-11.0 beats x min(-1), respectively), and for lactic acid (2.2+/-0.4, 4.6+/-0.7, 5.7+/-1.1, and 6.3+/-1.5 mM x l(-1), respectively). However, no significant differences were revealed between the various conditions when rate-perceived exertion data were analyzed, despite increased absolute loads. These data indicate that the psychological manipulation introduced in this study did not affect physiological responses during isometric exercise, in contrast to that seen during dynamic exercise.