Neuromuscular adjustments to unweighted running: the increase in hamstring activity is sensitive to trait anxiety

• DOI: 10.3389/fphys.2023.1212198
• Publication Date: 2023-06-02T14:17:13Z
• Authors: Camille Fazzari; Robin Macchi; Camélia Ressam; Yoko Kunimasa; Caroline Nicol; Cécile Martha; Benoît Bolmont; Patrick Sainton; Arnaud Hays; Fabrice Vercruyssen; Thomas Lapole; Martin Bossard; Rémy Casanova; Lionel Bringoux; Pascale Chavet
• Keywords: [SDV] Life Sciences [q-bio]; trait anxiety; reloading; Physiology; [SDV]Life Sciences [q-bio]; lower body positive pressure; running; 610; QP1-981; unweighting; neuromuscular adjustments; repeatability; 796

Introduction: Originally developed for astronauts, lower body positive pressure treadmills (LBPPTs) are increasingly being used in sports and clinical settings because they allow unweighted running. However, the neuromuscular adjustments to running remain understudied. They would be limited certain limb muscles interindividually variable. This study investigated whether this might related familiarization and/or trait anxiety. Methods: Forty healthy male runners were divided into two equal groups with contrasting levels of anxiety (high, ANX+, n = 20 vs. low, ANX-, 20). completed 9-min runs on a LBPPT. Each included three consecutive 3-min conditions performed at 100%, 60% (unweighted running), 100% weight. Normal ground reaction force electromyographic activity 11 ipsilateral analyzed last 30 s each condition both runs. Results: Unweighted showed muscle- stretch-shortening cycle phase-dependent that repeatable across Importantly, hamstring (BF, biceps femoris; STSM, semitendinosus/semimembranosus) muscle increased during braking (BF: +44 ± 18%, p < 0.001) push-off +49 12% STSM: +123 14%, 0.001 both) phases, even more so ANX+ than ANX-. During phase, only significant increases BF (+41 15%, STSM (+53 27%, activities. twofold increase compared ANX- (+119 10% +48 27, both). Conclusion: The phases may have accelerated subsequent swing free-leg, likely counteracting unweighting-induced slowing stride frequency. was pronounced an attempt not deviate from their preferred pattern. These results highlight importance individualizing LBPPT training rehabilitation protocols, particular attention individuals weak or injured hamstrings.