Assessing the Usefulness of Acute Physiological Responses Following Resistance Exercise: Sensitivity, Magnitude of Change and Time Course of Measures.

A variety of strategies exist to modulate acute physiological responses following resistance exercise aimed at enhancing recovery and/or adaptation processes. To assess the true impact of these strategies, it is important to know the ability of measures to detect meaningful change. We investigated the sensitivity of measures used to quantify acute physiological responses to resistance exercise and constructed a physiological profile to characterise the magnitude of change and time course of this response. Eight males, accustomed to regular resistance exercise, performed experimental sessions during a 'control week', void of an exercise stimulus. Participants repeated this sequence of experimental sessions the following week, termed the 'exercise week', except they performed a bout of lower-limb resistance exercise following baseline assessments. Assessments were conducted at baseline, 2, 6, 24, 48, 72 and 96 h post-intervention. Based on the signal-to-noise ratio, the most sensitive measures were maximal voluntary isometric contraction, 20m sprint, countermovement jump peak force, rate of force development (100-200ms), muscle soreness, daily analysis of life demands for athletes Part B, limb girth, matrix metalloproteinase-9, interleukin-6, creatine kinase and high sensitivity C-reactive protein with ratios of >1.5. There were clear changes in these measures following resistance exercise, determined via magnitude-based inferences. These findings highlight measures that can detect real changes in acute physiological responses following resistance exercise in trained individuals. Researchers investigating strategies to manipulate acute physiological responses for recovery and/or adaptation can use these measures, as well as recommended sampling points, to be confident that their interventions are making a worthwhile impact.