Effects of strict prolonged bed rest on cardiorespiratory fitness: systematic review and meta-analysis.
J Appl Physiol (1985)
; 123(4): 790-799, 2017 Oct 01.
Article
in En
| MEDLINE
| ID: mdl-28705999
ABSTRACT
The aim of this systematic review and meta-analysis [International Prospective Register of Systematic Reviews (PROSPERO) CRD42017055619] was to assess the effects of strict prolonged bed rest (without countermeasures) on maximal oxygen uptake (VÌo2max) and to explore sources of variation therein. Since 1949, 80 studies with a total of 949 participants (>90% men) have been published with data on strict bed rest and VÌo2max The studies were conducted mainly in young participants [median age (interquartile range) 24.5 (22.4-34.0) yr]. The duration of bed rest ranged from 1 to 90 days. VÌo2max declined linearly across bed rest duration. No statistical difference in the decline among studies reporting VÌo2max as l/min (-0.3% per day) compared with studies reporting VÌo2max normalized to body weight (ml·kg-1·min-1; -0.43% per day) was observed. Although both total body weight and lean body mass declined in response to bed rest, we did not see any associations with the decline in VÌo2max However, 15-26% of the variation in the decline in VÌo2max was explained by the pre-bed-rest VÌo2max levels, independent of the duration of bed rest (i.e., higher pre-bed-rest VÌo2max levels were associated with larger declines in VÌo2max). Furthermore, the systematic review revealed a gap in the knowledge about the cardiovascular response to extreme physical inactivity, particularly in older subjects and women of any age group. In addition to its relevance to spaceflight, this lack of data has significant translational implications because younger women sometimes undergo prolonged periods of bed rest associated with the complications of pregnancy and the incidence of hospitalization including prolonged periods of bed rest increases with age.NEW & NOTEWORTHY Large interindividual responses of maximal oxygen uptake (VÌo2max) to aerobic exercise training exist. However, less is known about the variability in the response of VÌo2max to prolonged bed rest. This systematic review and meta-analysis showed that pre-bed-rest VÌo2max values were inversely associated with the change in VÌo2max independent of the duration of bed rest. Moreover, we identified a large knowledge gap about the causes of decline in VÌo2max, particularly in postmenopausal women, which may have clinical implications.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Oxygen Consumption
/
Bed Rest
/
Cardiorespiratory Fitness
Type of study:
Systematic_reviews
Limits:
Humans
Language:
En
Journal:
J Appl Physiol (1985)
Journal subject:
FISIOLOGIA
Year:
2017
Type:
Article