Open AccessTreadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest
Author(s) -
Schneider Suzanne M.,
Lee Stuart M. C.,
Feiveson Alan H.,
Watenpaugh Donald E.,
Macias Brandon R.,
Hargens Alan R.
Publication year - 2016
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12892
Subject(s) - medicine , supine position , ankle , deconditioning , physical therapy , lean body mass , isometric exercise , treadmill , leg press , endurance training , physical medicine and rehabilitation , muscle strength , body weight , surgery
Leg muscle mass and strength are decreased during reduced activity and non‐weight‐bearing conditions such as bed rest ( BR ) and spaceflight. Supine treadmill exercise within lower body negative pressure ( LBNP EX ) provides full‐body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40‐min interval exercise protocol performed against LBNP EX 6 days week −1 would attenuate losses in leg lean mass ( LLM ), strength, and endurance during 6° head‐down tilt BR , with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non‐exercise control ( CON ) and the other twin as the exercise subject ( EX ). Before and after BR , LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre‐ to post‐ BR in the male CON subjects ( P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre‐ to post‐ BR changes were significant in the female subjects, either CON or EX , likely due to their lower pre‐ BR values. Importantly, the LBNP EX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit.