Changes in muscle size, architecture, and neural activation after 20 days of bed rest with and without resistance exercise

2001 ◽  
Vol 84 (1-2) ◽  
pp. 7-12 ◽  
Author(s):  
Yasuo Kawakami ◽  
Hiroshi Akima ◽  
Keitaro Kubo ◽  
Yoshiho Muraoka ◽  
Hiroshi Hasegawa ◽  
...  
Keyword(s):  
Resistance Exercise ◽  
Bed Rest ◽  
Muscle Size ◽  
Neural Activation

scholarly journals Impact of resistance exercise during bed rest on skeletal muscle sarcopenia and myosin isoform distribution

1998 ◽  
Vol 84 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Marcas M. Bamman ◽  
Mark S. F. Clarke ◽  
Daniel L. Feeback ◽  
Robert J. Talmadge ◽  
Bruce R. Stevens ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Exercise ◽  
Vastus Lateralis ◽  
Bed Rest ◽  
Vastus Lateralis Muscle ◽  
Neural Activation ◽  
Type I ◽  
Cross Sectional ◽  
Maximum Voluntary Isometric Contraction ◽  
Leg Press

Bamman, Marcas M., Mark S. F. Clarke, Daniel L. Feeback, Robert J. Talmadge, Bruce R. Stevens, Steven A. Lieberman, and Michael C. Greenisen. Impact of resistance exercise during bed rest on skeletal muscle sarcopenia and myosin isoform distribution. J. Appl. Physiol. 84(1): 157–163, 1998.—Because resistance exercise (REx) and bed-rest unloading (BRU) are associated with opposing adaptations, our purpose was to test the efficacy of REx against the effects of 14 days of BRU on the knee-extensor muscle group. Sixteen healthy men were randomly assigned to no exercise (NoEx; n = 8) or REx ( n = 8). REx performed five sets of leg press exercise with 80–85% of one repetition maximum (1 RM) every other day during BRU. Muscle samples were removed from the vastus lateralis muscle by percutaneous needle biopsy. Myofiber distribution was determined immunohistochemically with three monoclonal antibodies against myosin heavy chain (MHC) isoforms (I, IIa, IIx). MHC distribution was further assessed by quantitative gel electrophoresis. Dynamic 1-RM leg press and unilateral maximum voluntary isometric contraction (MVC) were determined. Maximal neural activation (root mean squared electromyogram) and rate of torque development (RTD) were measured during MVC. Reductions ( P < 0.05) in type I (15%) and type II (17%) myofiber cross-sectional areas were found in NoEx but not in REx. Electrophoresis revealed no changes in MHC isoform distribution. The percentage of type IIx myofibers decreased ( P < 0.05) in REx from 9 to 2% and did not change in NoEx. 1 RM was reduced ( P < 0.05) by 9% in NoEx but was unchanged in REx. MVC fell by 15 and 13% in NoEx and REx, respectively. The agonist-to-antagonist root mean squared electromyogram ratio decreased ( P < 0.05) 19% in REx. RTD slowed ( P < 0.05) by 54% in NoEx only. Results indicate that REx prevented BRU-induced myofiber atrophy and also maintained training-specific strength. Unlike spaceflight, BRU did not induce shifts in myosin phenotype. The reported benefits of REx may prove useful in prescribing exercise for astronauts in microgravity.

scholarly journals Resistance exercise maintains skeletal muscle protein synthesis during bed rest

1997 ◽  
Vol 82 (3) ◽  
pp. 807-810 ◽  
Author(s):  
Arny A. Ferrando ◽  
Kevin D. Tipton ◽  
Marcas M. Bamman ◽  
Robert R. Wolfe
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Training ◽  
Resistance Exercise ◽  
Lean Body Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Bed Rest ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis

Ferrando, Arny A., Kevin D. Tipton, Marcas M. Bamman, and Robert R. Wolfe. Resistance exercise maintains skeletal muscle protein synthesis during bed rest. J. Appl. Physiol. 82(3): 807–810, 1997.—Spaceflight results in a loss of lean body mass and muscular strength. A ground-based model for microgravity, bed rest, results in a loss of lean body mass due to a decrease in muscle protein synthesis (MPS). Resistance training is suggested as a proposed countermeasure for spaceflight-induced atrophy because it is known to increase both MPS and skeletal muscle strength. We therefore hypothesized that scheduled resistance training throughout bed rest would ameliorate the decrease in MPS. Two groups of healthy volunteers were studied during 14 days of simulated microgravity. One group adhered to strict bed rest (BR; n = 5), whereas a second group engaged in leg resistance exercise every other day throughout bed rest (BREx; n = 6). MPS was determined directly by the incorporation of infusedl-[ ring-13C6]phenylalanine into vastus lateralis protein. After 14 days of bed rest, MPS in the BREx group did not change and was significantly greater than in the BR group. Thus moderate-resistance exercise can counteract the decrease in MPS during bed rest.

scholarly journals Variability of neural activation during walking in humans: short heels and big calves

2011 ◽  
Vol 7 (4) ◽  
pp. 539-542 ◽  
Author(s):  
A. N. Ahn ◽  
J. K. Kang ◽  
M. A. Quitt ◽  
B. C. Davidson ◽  
C. T. Nguyen
Keyword(s):  
Neural Control ◽  
Calf Muscle ◽  
Medial Gastrocnemius ◽  
Muscle Size ◽  
Neural Activation ◽  
Neural Signals ◽  
Recruitment Pattern ◽  
Moment Arms ◽  
Different Shapes ◽  
Calf Muscles

People come in different shapes and sizes. In particular, calf muscle size in humans varies considerably. One possible cause for the different shapes of calf muscles is the inherent difference in neural signals sent to these muscles during walking. In sedentary adults, the variability in neural control of the calf muscles was examined with muscle size, walking kinematics and limb morphometrics. Half the subjects walked while activating their medial gastrocnemius (MG) muscles more strongly than their lateral gastrocnemius (LG) muscles during most walking speeds (‘MG-biased’). The other subjects walked while activating their MG and LG muscles nearly equally (‘unbiased’). Those who walked with an MG-biased recruitment pattern also had thicker MG muscles and shorter heel lengths, or MG muscle moment arms, than unbiased walkers, but were similar in height, weight, lower limb length, foot length, and exhibited similar walking kinematics. The relatively less plastic skeletal system may drive calf muscle size and motor recruitment patterns of walking in humans.

Protein Metabolism and Age: Influence of Insulin and Resistance Exercise

2001 ◽  
Vol 11 (s1) ◽  
pp. S150-S163 ◽  
Author(s):  
Peter A. Farrell
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mrna Translation ◽  
Bed Rest ◽  
Skeletal Muscle Protein ◽  
Amino Acid Availability ◽  
Effects Of Aging

Skeletal muscle proteins are constantly being synthesized and degraded, and the net balance between synthesis and degradation determines the resultant muscle mass. Biochemical pathways that control protein synthesis are complex, and the following must be considered: gene transcription, mRNA splicing, and transport to the cytoplasm; specific amino acyl-tRNA, messenger (mRNA), ribosomal (rRNA) availability; amino acid availability within the cell; the hormonal milieu; rates of mRNA translation; packaging in vesicles for some types of proteins; and post-translational processing such as glycation and phosphorylation/dephosphorylation. Each of these processes is responsive to the need for greater or lesser production of new proteins, and many states such as sepsis, uncontrolled diabetes, prolonged bed-rest, aging, chronic alcohol treatment, and starvation cause marked reductions in rates of skeletal muscle protein synthesis. In contrast, acute and chronic resistance exercise cause elevations in rates of muscle protein synthesis above rates found in nondiseased rested organisms, which are normally fed. Resistance exercise may be unique in this capacity. This chapter focuses on studies that have used exercise to elucidate mechanisms that explain elevations in rates of protein synthesis. Very few studies have investigated the effects of aging on these mechanisms; however, the literature that is available is reviewed.

Inactivity and muscle: effect of resistance training during bed rest on muscle size in the lower limb

2001 ◽  
Vol 172 (4) ◽  
pp. 269-278 ◽  
Author(s):  
H. Akima ◽  
K. Kubo ◽  
M. Imai ◽  
H. Kanehisa ◽  
Y. Suzuki ◽  
...  
Keyword(s):  
Resistance Training ◽  
Lower Limb ◽  
Bed Rest ◽  
Muscle Size

scholarly journals Skeletal Muscle Quality: A Biomarker for Assessing Physical Performance Capabilities in Young Populations

2021 ◽  
Vol 12 ◽  
Author(s):  
Marshall A. Naimo ◽  
Alyssa N. Varanoske ◽  
Julie M. Hughes ◽  
Stefan M. Pasiakos
Keyword(s):  
Exercise Training ◽  
Resistance Exercise ◽  
Functional Capacity ◽  
Assessment Tool ◽  
Evidence Base ◽  
Muscle Quality ◽  
Muscle Size ◽  
Functional Responses ◽  
Resistance Exercise Training ◽  
Training Interventions

Muscle quality (MQ), defined as the amount of strength and/or power per unit of muscle mass, is a novel index of functional capacity that is increasingly relied upon as a critical biomarker of muscle health in low functioning aging and pathophysiological adult populations. Understanding the phenotypical attributes of MQ and how to use it as an assessment tool to explore the efficacy of resistance exercise training interventions that prioritize functional enhancement over increases in muscle size may have implications for populations beyond compromised adults, including healthy young adults who routinely perform physically demanding tasks for competitive or occupational purposes. However, MQ has received far less attention in healthy young populations than it has in compromised adults. Researchers and practitioners continue to rely upon static measures of lean mass or isolated measures of strength and power, rather than using MQ, to assess integrated functional responses to resistance exercise training and physical stress. Therefore, this review will critically examine MQ and the evidence base to establish this metric as a practical and important biomarker for functional capacity and performance in healthy, young populations. Interventions that enhance MQ, such as high-intensity stretch shortening contraction resistance exercise training, will be highlighted. Finally, we will explore the potential to leverage MQ as a practical assessment tool to evaluate function and enhance performance in young populations in non-traditional research settings.

Resistance exercise prevents plantar flexor deconditioning during bed rest

1997 ◽  
Vol 29 (11) ◽  
pp. 1462-1468 ◽  
Author(s):  
MARCAS M. BAMMAN ◽  
GARY R. HUNTER ◽  
BRUCE R. STEVENS ◽  
MARK E. GUILLIAMS ◽  
MICHAEL C. GREENISEN
Keyword(s):  
Resistance Exercise ◽  
Bed Rest ◽  
Plantar Flexor
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