Arent, S. M., Legatt, J., Diver, T., Pellegrino, J., & Alderman, B. L. ((2006). State anxiety and biochemical responses to different resistance training intensities: The role of muscular failure. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 2001.

"Much of the research examining affective changes following resistance training has relied on an exercise intensity based on the percentage of 1 RM. However, physiological evidence suggests that “intensity” and “load” may not be synonymous, as has been traditionally promoted". This study examined the concept of resistance exercise intensity by comparing multiple methods of resistance training and the resultant biochemical and affective responses. By manipulating either load or repetition speed while holding volume constant, it was assumed possible to distinguish the effects of exercise “intensity” from exercise “load.” Post-adolescent males and females (N = 19) completed three different resistance training protocols (75% 10 RM [M], 75% 10 RM with an emphasized eccentric contraction [E], and 100% 10 RM [H]) and a no-treatment control condition [C]. State anxiety was assessed immediately before and at 0-5, 15, 30, 45, and 60 minutes post-exercise. To assess physiological demands, blood lactate was assessed before, during, and 0, 15, and 30 minutes post-exercise and salivary cortisol was assessed immediately before and 0, 30, and 60 minutes post-exercise. Average RPE was also determined for each condition.

State anxiety scores revealed a significant condition x time interaction. Follow-up tests indicated that the M condition produced improvements in anxiety during recovery, while both the H and E conditions resulted in an immediate, transient anxiogenic effect, before returning toward baseline. There were no changes in the control group. Significant condition x time interactions were found for both blood lactate and salivary cortisol. Both the H and E conditions resulted in similar peak lactate values by the end of the training sessions, which were higher than either the M and C conditions. Lactate was higher in the M condition than in the control, with the control group not increasing above baseline. Both the H and E conditions resulted in increased salivary cortisol after exercise, while the M and C conditions produced decreased cortisol values over recovery and were not different from one another. A significant effect for RPE paralleled the pattern of results for lactate.

Implication. Physiological and affective responses to these exercise protocols suggest that the important consideration when defining resistance training intensity is “how lifting is performed” rather than “how much is lifted.” It also appears that moderate intensity resistance training, when properly defined, results in a more optimal challenge to the system and enduring anxiolytic responses.

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