Physiological and Biomechanical Responses of Highly Trained Distance Runners to Lower-Body Positive Pressure Treadmill Running

Abstract

BackgroundAs a way to train at faster running speeds, add training volume, prevent injury, or rehabilitate after an injury, lower-body positive pressure treadmills (LBPPT) have become increasingly commonplace among athletes. However, there are conflicting evidence and a paucity of data describing the physiological and biomechanical responses to LBPPT running in highly trained or elite caliber runners at the running speeds they habitually train at, which are considerably faster than those of recreational runners. Furthermore, data is lacking regarding female runners’ responses to LBPPT running. Therefore, this study was designed to evaluate the physiological and biomechanical responses to LBPPT running in highly trained male and female distance runners.MethodsFifteen highly trained distance runners (seven male; eight female) completed a single running test composed of 4 × 9-min interval series at fixed percentages of body weight ranging from 0 to 30% body weight support (BWS) in 10% increments on LBPPT. The first interval was always conducted at 0% BWS; thereafter, intervals at 10, 20, and 30% BWS were conducted in random order. Each interval consisted of three stages of 3 min each, at velocities of 14.5, 16.1, and 17.7 km·h−1 for men and 12.9, 14.5, and 16.1 km·h−1 for women. Expired gases, ventilation, breathing frequency, heart rate (HR), rating of perceived exertion (RPE), and stride characteristics were measured during each running speed and BWS.ResultsMale and female runners had similar physiological and biomechanical responses to running on LBPPT. Increasing BWS increased stride length (p < 0.02) and flight duration (p < 0.01) and decreased stride rate (p < 0.01) and contact time (p < 0.01) in small-large magnitudes. There was a large attenuation of oxygen consumption (VO2) relative to BWS (p < 0.001), while there were trivial-moderate reductions in respiratory exchange ratio, minute ventilation, and respiratory frequency (p > 0.05), and small-large effects on HR and RPE (p < 0.01). There were trivial-small differences in VE, respiratory frequency, HR, and RPE for a given VO2 across various BWS (p > 0.05).ConclusionsThe results indicate the male and female distance runners have similar physiological and biomechanical responses to LBPPT running. Overall, the biomechanical changes during LBPPT running all contributed to less metabolic cost and corresponding physiological changes.

An interdisciplinary examination of attentional focus strategies used during running gait retraining

“…Other physiological and perceptual indices such as heart rate, blood lactate levels, and ratings of perceived exertion (RPE) have consistently produced null effects in studies examining attentional focus, even though changes have been observed. This is contrary to biomechanical and physiological studies that find consistent economical changes reflected in , heart rate, and RPE (eg, Barnes & Janecke). A more integrated approach that adopts biomechanical, physiological, and perceptual indices to examine movement economy and a control condition may produce clearer results.…”

Energy Cost of Running Under Hypogravity in Well-Trained Runners and Triathletes: A Biomechanical Perspective

“…Treadmill running under artificial hypogravity has recently entered the focus of sports science and medicine, and gained increasing popularity. Originally offering an alternative training tool for running with reduced musculoskeletal loading in posttraumatic rehabilitation or for injury prevention (Kline et al, 2015), hypogravity running has recently also been employed for competitive training purposes such as supramaximal speed training (Barnes & Janecke, 2017;. Artificial hypogravity is commonly achieved by specialized instrumented treadmills, which either lift the athlete mechanically (Donelan & Kram, 2000;Polet et al, 2017;Polet, Schroeder, & Bertram, 2018) or by means of positive air pressure inside a chamber around the lower limbs and pelvis of the athlete, lifting the runner upwards.…”

“…Artificial hypogravity is commonly achieved by specialized instrumented treadmills, which either lift the athlete mechanically (Donelan & Kram, 2000;Polet et al, 2017;Polet, Schroeder, & Bertram, 2018) or by means of positive air pressure inside a chamber around the lower limbs and pelvis of the athlete, lifting the runner upwards. The latter technological concept is known as "lower body positive pressure treadmill" (LBPPT) (Barnes & Janecke, 2017;Kline et al, 2015;McNeill, Kline, et al, 2015) and is applied, e.g., by the commercial product AlterG ® Anti-Gravity Treadmill®. On the AlterG ® , the effective body weight can be reduced from 100 % down to 20 %, which roughly corresponds to the weight reduction experienced on the Moon.…”

“…: 630 N or 560 N vs. originally 700 N) but not further, since beyond 80 %, running specificity might be lost because of substantial biomechanical adaptations, such as decreased step frequency etc. (Barnes & Janecke, 2017;Fleckenstein et al, 2018;Kline et al, 2015;Ueberschär, Fleckenstein, Wüstenfeld, et al, 2019).…”

“…Detailed research has been conducted to elucidate the physiological adaptations and implicatio ns of hypogravity treadmill running (Barnes & Janecke, 2017;Fleckenstein et al, 2018;McNeill, de Heer, Williams, & Coast, 2015;McNeill, Kline, et al, 2015), confir ming that hypogravity running leads to lower physiological demands than running under normal gravity. Thereby, hypogravity allows an athlete either to run faster, or to reduce the physiologica l session load for a fixed running speed.…”