Compression under pressure: physiological and methodological factors influencing the effect of compression garments on running economy

Evidence for the effects of compression garments on sports performance and physiological responses to dynamic exercise remains equivocal. Contradictory findings within the sporting literature are confounded by methodological heterogeneity in terms of; intensity and modality of exercise, type of garment worn, and the interface pressure produced by the garment. The interface pressure applied by compression clothing is an important measure in evaluating the bio-physical impact of compression. Interface pressure values obtained in vivo with two portable pressure devices (PicoPress and Kikuhime) were compared against a reference standard (HOSY). The PicoPress satisfied the a priori thresholds for acceptable validity at the posterior and lateral orientation with calf stockings and tights, confirming its future use to assess interface pressure. A small, likely beneficial improvement in running economy was observed with correctly fitted (95%:5%:0%; η2 = 0.55) but not oversized compression tights, indicating that a certain level of interface pressure is required. Compression tights improved running economy only at higher relative exercise intensities (77.7 - 91.5% V̇O2max). The absence of any improvement at lower intensities (67.1 - 77.6 % V̇O2max) suggest that changes in running economy from compression are dependent on relative exercise intensity when V̇O2max (%) is used as an anchor of exercise intensity. Comparing measures from two portable, wireless near-infrared spectroscopy (NIRS) devices (PortaMon and MOXY) we found that the low-cost and light-weight MOXY device gave tissue oxygen saturation values at rest and during exercise that were physiologically credible and suitable for future research. Compression tights did affect ground contact time but not tissue oxygen saturation, cardiovascular or other kinematic parameters during running at intensities equivalent to long-distance race speed. Compression tights can produce small improvements in running economy, but effects are restricted to higher intensity exercise and appear dependent on garment interface pressure. It remains unlikely that this small positive effect on running economy, in very specific conditions, is enough to result in a meaningful impact on running performance.