Efficacy of a gravity‐independent resistance exercise device as a countermeasure to muscle atrophy during 29‐day bed rest

Alkner, Björn; Tesch, Per A.

doi:10.1111/j.1365-201x.2004.01293.x

Cited by 135 publications

(141 citation statements)

References 46 publications

(127 reference statements)

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“…For the exercise group, resistance training was performed at maximal effort on a flywheel ergometer (14) to train the thigh muscle groups using supine squat exercises. Nineteen training sessions of 35 min were programmed every 3 days, as previously described (9,15).…”

Section: Methodsmentioning

confidence: 99%

Physical Inactivity Differentially Alters Dietary Oleate and Palmitate Trafficking

et al. 2009

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1OBJECTIVE-Obesity and diabetes are characterized by the incapacity to use fat as fuel. We hypothesized that this reduced fat oxidation is secondary to a sedentary lifestyle. RESEARCH DESIGN AND METHODS-We investigated the effect of a 2-month bed rest on the dietary oleate and palmitate trafficking in lean women (control group, n ϭ 8) and the effect of concomitant resistance/aerobic exercise training as a countermeasure (exercise group, n ϭ 8). Trafficking of stable isotope-labeled dietary fats was combined with muscle gene expression and magnetic resonance imaging-derived muscle fat content analyses. 31 ]palmitate oxidation by Ϫ8.2 Ϯ 4.9% (P Ͻ 0.0001). Despite a decreased spontaneous energy intake and a reduction of 1.9 Ϯ 0.3 kg (P ϭ 0.001) in fat mass, exercise training did not mitigate these alterations but partially maintained fat-free mass, insulin sensitivity, and total lipid oxidation in fasting and fed states. In both groups, muscle fat content increased by 2.7% after bed rest and negatively correlated with the reduction in [d 31 ]palmitate oxidation (r 2 ϭ 0.48, P ϭ 0.003). I n our search of the environmental factors that fuelled the pandemic of obesity, we face a paradox. Although sedentary lifestyle has been highlighted for decades as one of the main factors triggering weight gain, the physiology of physical inactivity has received little attention (1). Clearly, the causal relationships between sedentary behaviors and obesity are essentially based on epidemiological studies or on the indirect beneficial effects of exercise training (2). None of these studies provide evidence to support a cause-and-effect relationship. RESULTS-In CONCLUSIONS-WhileObesity is a fat storage disease characterized by insulin resistance and a decreased capacity to oxidize lipids (3) in fasting (4) and postprandial (5) conditions. Because weight reduction was not associated with improvement in fat utilization (6), it was suggested as a primary impairment in the etiology of obesity, rather than an adaptive response. Consequently, the delineation of the causes responsible for this reduced capacity to oxidize fat appears to be a fundamental prerequisite to develop efficient strategies against obesity.We previously extended the early Mayer hypothesis (7) and hypothesized that the decreased fat oxidation observed in obese and postobese subjects is due to the generalized adoption of sedentary behaviors (8). Using strict bed rest as a model, we showed that physical inactivity, per se (i.e., independent of the known physical inactivity-induced energy balance changes), lowers fasting and postprandial fat oxidation (9). Unexpectedly, whereas monounsaturated dietary fat (oleate) oxidation remained unaffected by bed rest, saturated fat (palmitate) oxidation decreased by 11% (9). These results are interesting when considering the north/south gradient in obesity prevalence in France that was not associated with the overall energy intake but in the greater amount of saturated fat in the diet (10).The main objective of our present study wa...

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Section: Methodsmentioning

confidence: 99%

Physical Inactivity Differentially Alters Dietary Oleate and Palmitate Trafficking

et al. 2009

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“…The mechanisms by which contractile activity preserves muscle mass, even in the face of catabolic signals (14)(15)(16)(17), have long been a mystery. Muscle wasting does not occur similarly in all types of muscle fiber.…”

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confidence: 99%

PGC-1α protects skeletal muscle from atrophy by suppressing FoxO3 action and atrophy-specific gene transcription

Sandri

Lin

Handschin

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

897

871

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Maintaining muscle size and fiber composition requires contractile activity. Increased activity stimulates expression of the transcriptional coactivator PGC-1␣ (peroxisome proliferator-activated receptor ␥ coactivator 1␣), which promotes fiber-type switching from glycolytic toward more oxidative fibers. In response to disuse or denervation, but also in fasting and many systemic diseases, muscles undergo marked atrophy through a common set of transcriptional changes. FoxO family transcription factors play a critical role in this loss of cell protein, and when activated, FoxO3 causes expression of the atrophy-related ubiquitin ligases atrogin-1 and MuRF-1 and profound loss of muscle mass. To understand how exercise might retard muscle atrophy, we investigated the possible interplay between PGC-1␣ and the FoxO family in regulation of muscle size. Rodent muscles showed a large decrease in PGC-1␣ mRNA during atrophy induced by denervation as well as by cancer cachexia, diabetes, and renal failure. Furthermore, in transgenic mice overexpressing PGC-1␣, denervation and fasting caused a much smaller decrease in muscle fiber diameter and a smaller induction of atrogin-1 and MuRF-1 than in control mice. Increased expression of PGC-1␣ also increased mRNA for several genes involved in energy metabolism whose expression decreases during atrophy. Transfection of PGC-1␣ into adult fibers reduced the capacity of FoxO3 to cause fiber atrophy and to bind to and transcribe from the atrogin-1 promoter. Thus, the high levels of PGC-1␣ in dark and exercising muscles can explain their resistance to atrophy, and the rapid fall in PGC-1␣ during atrophy should enhance the FoxO-dependent loss of muscle mass.denervation ͉ fasting ͉ muscle fiber ͉ energy metabolism ͉ mitochondria

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“…The inertial ergometer is a gravity-independent resistance exercise device incorporating a flywheel mechanism that allows for concentric and eccentric force development over a full range of motion for a given muscle group. For the current study, the flywheel device was positioned so that all thigh and calf exercises were completed with the subject in the 6°head-down tilt position as shown and described previously (1,2). Resistance exercise was scheduled for each subject approximately every third day (2-3 days/wk) beginning on day 2 of bed rest for a total of 19 sessions.…”

Section: Countermeasures To Bed Restmentioning

confidence: 99%

“…The BRE group trained the calf muscles using calf press (CP) exercises on an inertial ergometer (1)(2)(3)55). The inertial ergometer is a gravity-independent resistance exercise device incorporating a flywheel mechanism that allows for concentric and eccentric force development over a full range of motion for a given muscle group.…”

Section: Countermeasures To Bed Restmentioning

confidence: 99%

Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest

Trappe

Creer

Minchev

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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December 19, 2007; doi:10.1152/ajpregu.00761.2007.-The soleus muscle has been consistently shown to atrophy more than other leg muscles during unloading and is difficult to protect using various exercise countermeasure paradigms. However, the efficacy of aerobic exercise, a known stimulus for oxidative adaptations, has not been tested in combination with resistance exercise (RE), a known hypertrophic stimulus. We hypothesized that a concurrent exercise program (AE ϩ RE) would preserve soleus fiber myosin heavy chain (MHC) I size and function during 60 days of bed rest. A secondary objective was to test the hypothesis that a leucine-enriched high protein diet would partially protect soleus single fiber characteristics. Soleus muscle biopsies were obtained before and after bed rest from a control (BR; n ϭ 7), nutrition (BRN; n ϭ 8), and exercise (BRE; n ϭ 6) group. Single muscle fiber diameter (Dia), peak force (Po), contractile velocity, and power were studied. BR decreased (P Ͻ 0.05) MHC I Dia (Ϫ14%), Po (Ϫ38%), and power (Ϫ39%) with no change in contractile velocity. Changes in MHC I size (Ϫ13%) and contractile function (ϳ30%) from BRN were similar to BR. BRE decreased (P Ͻ 0.05) MHC I Dia (Ϫ13%) and Po (Ϫ23%), while contractile velocity increased (P Ͻ 0.05) 26% and maintained power. These soleus muscle data show 1) the AE ϩ RE exercise program maintained MHC I power but not size and strength, and 2) the nutrition countermeasure did not benefit single fiber size and contractile function. The divergent response in size and functional MHC I soleus properties with the concurrent exercise program was a unique finding further highlighting the challenges of protecting the unloaded soleus. skeletal muscle; contractile properties; exercise; microgravity; spaceflight; Women's International Space Exploration (WISE) 2005 HUMAN BED REST STUDIES of 3-4 mo in duration have found the calf muscles to atrophy ϳ30%, which is ϳ10 -15% greater than the thigh muscles (2, 32, 43). Rodents subjected to hindlimb suspension consistently show that the soleus muscle atrophies more compared with other leg muscles (48). Numerous animal studies (17,24,30,58) have not been able to completely protect soleus muscle mass and function during unloading using a wide range of resistive-type muscle loading paradigms. In humans, slow-twitch muscle fiber size and contractile function are only partially protected (ϳ50%) with resistance exercise during long-term bed rest (52). Thus, leg muscles containing slow-twitch fibers, particularly the soleus, need to be targeted by an exercise prescription program beyond previous resistance exercise-related programs. Aerobic exercise is a potential candidate given the sustained involvement of slow-twitch muscle fibers during these types of activities (41). While aerobic activity during space travel has been extensively studied and proven to be beneficial for cardiovascular health dating back to Skylab experiments (14, 39, 40), it has not been systematically evaluated in combination with resistance exercise to as...

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Efficacy of a gravity‐independent resistance exercise device as a countermeasure to muscle atrophy during 29‐day bed rest

Abstract: The present data suggest that this resistance exercise paradigm counteracts quadriceps and abates the more substantial triceps surae muscle atrophy in bedridden subjects, and therefore should be an important asset to space travellers.

Cited by 135 publications

References 46 publications

Physical Inactivity Differentially Alters Dietary Oleate and Palmitate Trafficking

Physical Inactivity Differentially Alters Dietary Oleate and Palmitate Trafficking

PGC-1α protects skeletal muscle from atrophy by suppressing FoxO3 action and atrophy-specific gene transcription

Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest

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