Running vs. resistance exercise to counteract deconditioning induced by 90-day head-down bedrest

• Published in: Frontiers in physiology 2022-08, Vol.13, p.902983-902983
• Main Authors: Robin, Adrien, Wang, Linjie, Custaud, Marc-Antoine, Liu, Jiexin, Yuan, Min, Li, Zhili, Lloret, Jean-Christophe, Liu, Shujuan, Dai, Xiaoqian, Zhang, Jianfeng, Lv, Ke, Li, Wenjiong, Gauquelin-Koch, Guillemette, Wang, Huijuan, Li, Kai, Li, Xiaotao, Qu, Lina, Navasiolava, Nastassia, Li, Yinghui
• Format: Article
• Language: English
• Subjects: cardiovascular deconditioning; countermeasure; HDBR; maximal working capacity; microgravity; orthostatic tolerance; Physiology
• ISSN: 1664-042X; 1664-042X
• DOI: 10.3389/fphys.2022.902983

Spaceflight is associated with enhanced inactivity, resulting in muscular and cardiovascular deconditioning. Although physical exercise is commonly used as a countermeasure, separate applications of running and resistive exercise modalities have never been directly compared during long-term bedrest. This study aimed to compare the effectiveness of two exercise countermeasure programs, running and resistance training, applied separately, for counteracting cardiovascular deconditioning induced by 90-day head-down bedrest (HDBR). Maximal oxygen uptake ( V ˙ O 2 max), orthostatic tolerance, continuous ECG and blood pressure (BP), body composition, and leg circumferences were measured in the control group (CON: n = 8), running exercise group (RUN: n = 7), and resistive exercise group (RES: n = 7). After HDBR, the decrease in V ˙ O 2 max was prevented by RUN countermeasure and limited by RES countermeasure (−26% in CON p < 0.05, −15% in RES p < 0.05, and −4% in RUN ns ). Subjects demonstrated surprisingly modest orthostatic tolerance decrease for different groups, including controls. Lean mass loss was limited by RES and RUN protocols (−10% in CON vs. −5% to 6% in RES and RUN). Both countermeasures prevented the loss in thigh circumference (−7% in CON p < 0.05, −2% in RES ns , and −0.6% in RUN ns ) and limited loss in calf circumference (−10% in CON vs. −7% in RES vs. −5% in RUN). Day–night variations in systolic BP were preserved during HDBR. Decrease in V ˙ O 2 max positively correlated with decrease in thigh ( r = 0.54 and p = 0.009) and calf ( r = 0.52 and p = 0.012) circumferences. During this 90-day strict HDBR, running exercise successfully preserved V ˙ O 2 max, and resistance exercise limited its decline. Both countermeasures limited loss in global lean mass and leg circumferences. The V ˙ O 2 max reduction seems to be conditioned more by muscular than by cardiovascular parameters.