Ratings of perceived exertion at the lactate threshold in trained and untrained men and women.

The purpose of this study was to investigate the effects of state of training and gender on ratings of perceived exertion (RPE) at the lactate threshold (LT), and to determine whether RPE during moderate to heavy sub-maximal exercise is more closely associated with LT or %VO2max. RPE at the LT (RPELT) and at various percentages of VO2max were compared in 10 male and 10 female trained distance runners, and 10 male and 10 female untrained subjects, 18 to 35 yr of age. Mean (+/- SD) VO2max [ml X kg FFW-1 (fat-free weight) X min-1] of the trained men and women (72.3 +/- 1.4 and 73.1 +/- 1.6) was significantly higher (P less than 0.05) than for the untrained men and women (60.2 +/- 1.4 and 53.2 +/- 1.8), confirming their higher cardiorespiratory capacity. Similarly, the mean LTs (%VO2max) of the trained men and women (79.2 +/- 1.7% and 73.3 +/- 1.8%) were significantly higher (P less than 0.05) than for the untrained men and women (66.5 +/- 3.3% and 58.9 +/- 3.3%), and mean values for the men were significantly higher (P less than 0.05) than for the women. The means for RPELT for the four groups, 13.6 +/- 2.1, 13.5 +/- 1.6, 13.5 +/- 1.5, and 12.9 +/- 1.3, respectively, were not significantly different (P greater than 0.05), even though the ratings were given at markedly different levels of VE, VO2 (1 X min-1), heart rate, and %VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma volume change during heavy-resistance weight lifting.

Blood samples were obtained from six young men before, and over a 60-min period following a bout of heavy-resistance weight lifting to determine changes in plasma volume. Weight lifting consisted of three sets of four exercises (arm curl, bench press, bent-arm row, and squat) performed using 70% of one-repetition maximum for as many repetitions as possible. Plasma volume change was determined from haematocrit and haemoglobin concentration. During weight lifting, mean oxygen uptake and heart rate were 1.96 L X min-1 and 158 bt X min-1, respectively. Plasma volume was decreased -14.3% (p less than 0.05) immediately following exercise and -7.0% (p less than 0.05) at 15 min into recovery, but had returned to the resting level within 30 min. It was concluded that heavy-resistance weight lifting elicits a significant decrease in plasma volume, which is similar in magnitude to that observed during running and cycling at 80-95% of maximal oxygen uptake.