In:
Frontiers in Physiology, Frontiers Media SA, Vol. 13 ( 2022-8-31)
Abstract:
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 & lt; 0.05, −15% in RES p & lt; 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 & lt; 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.
Type of Medium:
Online Resource
ISSN:
1664-042X
DOI:
10.3389/fphys.2022.902983
DOI:
10.3389/fphys.2022.902983.s001
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2022
detail.hit.zdb_id:
2564217-0
