Effects of 17-day spaceflight on electrically evoked torque and cross-sectional area of the human triceps surae

Narici, Marco V.; Kayser, Bengt; Barattini, Paolo; Cerretelli, Paolo

doi:10.1007/s00421-003-0955-7

Cited by 48 publications

(41 citation statements)

References 30 publications

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“…Interestingly, in the same crew members, neither electrically evoked contractile force assessed in-flight (Narici et al 2003) nor in vivo voluntary strength measured upon landing ) decreased despite triceps surae muscle atrophy (LeBlanc et al 2000). These data are in frank contrast to the present results, which do suggest that MVC decreases as a consequence of the absence of weight bearing accompanied by muscle protein loss.…”

Section: Musclecontrasting

confidence: 81%

“…In addition, crosssectional area of knee extensor and flexor as well as gluteal muscles was measured pre-and post-flight. In the same crew, investigators have previously reported no decrease in electrically evoked contractile force during the flight (Narici et al 2003), or in-vivo plantar flexor strength or fiber size ) upon landing. Since the astronauts were subjected to extensive and frequent in-flight muscle function testing involving the plantar flexors, it has been suggested this may have served as a ''resistance training countermeasure to attenuate whole muscle strength loss''.…”

Section: Introductionmentioning

confidence: 88%

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Effects of 17-day spaceflight on knee extensor muscle function and size

et al. 2004

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It is generally held that space travelers experience muscle dysfunction and atrophy during exposure to microgravity. However, observations are scarce and reports somewhat inconsistent with regard to the time course, specificity and magnitude of such changes. Hence, we examined four male astronauts (group mean approximately 43 years, 86 kg and 183 cm) before and after a 17-day spaceflight (Space Transport System-78). Knee extensor muscle function was measured during maximal bilateral voluntary isometric and iso-inertial concentric, and eccentric actions. Cross-sectional area (CSA) of the knee extensor and flexor, and gluteal muscle groups was assessed by means of magnetic resonance imaging. The decrease in strength (P<0.05) across different muscle actions after spaceflight amounted to 10%. Eight ambulatory men, examined on two occasions 20 days apart, showed unchanged (P>0.05) muscle strength. CSA of the knee extensor and gluteal muscles, each decreased (P<0.05) by 8%. Knee flexor muscle CSA showed no significant (P>0.05) change. The magnitude of these changes concord with earlier results from ground-based studies of similar duration. The results of this study, however, do contrast with the findings of no decrease in maximal voluntary ankle plantar flexor force previously reported in the same crew.

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Section: Musclecontrasting

confidence: 81%

Section: Introductionmentioning

confidence: 88%

Effects of 17-day spaceflight on knee extensor muscle function and size

et al. 2004

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“…However, many other studies in rats (Gardetto et al 1989) and in humans (Larsson et al 1996;Narici et al 2003;Widrick et al 1999) showed that specific tension (i.e., force per CSA) of single fibers (Gardetto et al 1989;Larsson et al 1996;Widrick et al 1999) or whole muscle (Narici et al 2003) can also be reduced following hindlimb suspension (Gardetto et al 1989), bed-rest (Larsson et al 1996) or spaceflight (Narici et al 2003;Widrick et al 1999) experiments. Muscle damage (Narici et al 2003) and/or a decreased number of force-generating cross-bridges (Gardetto et al 1989;Larsson et al 1996;Widrick et al 1999) are classically proposed to explain this latter alteration. It can therefore be conjectured that the decrement in strength induced by the present immobilization treatment could be partially ascribed to muscular changes (i.e., muscular atrophy or specific tension decrement), although this was not directly quantified.…”

Section: Discussionmentioning

confidence: 97%

Neural activation of the triceps surae is impaired following 2�weeks of immobilization

et al. 2004

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The purpose of this study was to investigate the effect of 2 weeks of ankle joint immobilization on triceps surae neural activation, with particular emphasis on the potential differences between the monoarticular soleus and the biarticular gastrocnemius muscles. Seventeen male volunteers were divided into the immobilized group (IG, n = 8) and the control group (CG, n = 9). Elastic adhesive bandages and an ankle stabilization orthosis were used to immobilize the ankle joint only. The plantar flexor torque obtained during maximal voluntary contractions (MVC) and after single, paired and tetanic stimuli applied at rest was measured. The associated EMG activity from the soleus and gastrocnemius muscles was also recorded, and their activation levels were estimated by means of the twitch interpolation technique. After immobilization, triceps surae maximal voluntary torque significantly decreased by 17% (P < 0.001). Strength losses were accompanied by a decrement in activation level (-6%, average of the three techniques used) and in maximal 100 Hz tetanic force (-11%). A significant decrease in the soleus (-22%, P < 0.05) but not in the gastrocnemius EMG activity, normalized to respective M-waves, was also found. It was concluded that the reduced voluntary torque output after immobilization could be attributed to both muscular and neural alterations. These latter selectively involved the monoarticular soleus muscle, while neural drive to the biarticular gastrocnemii, which had not been immobilized in their function as knee flexors, was preserved.

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“…A spaceXight study supports this suggestion. It has been observed that 17 days of spaceXight resulted in signiWcant changes in muscle function during the recovery phase and not in microgravity (Narici et al 2003). Furthermore, unloading has been shown to increase the vulnerability to injury from ECC exercise.…”

Section: Discussionmentioning

confidence: 98%

The influence of training status on the drop in muscle strength after acute exercise

et al. 2009

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Skeletal muscles fatigue after exercise, and reductions in maximal force appear. A difference in training status between the legs was introduced by unilateral immobilization of the calf muscles for 2 weeks in young men, who were randomly assigned to two groups, either a RUN group (n = 8) that was exposed to prolonged exercise (1-h running: individual pace) or a REST group (n = 12) that did no exercise after immobilization. Cross-sectional area (CSA) of the triceps-surae muscles was calculated by magnetic resonance imaging (MRI), and maximal voluntary contraction (MVC) force of the plantar flexors was measured before and after immobilization and after the running protocol. The CSA of triceps-surae muscles decreased significantly with a 7% reduction in both groups. A significant drop in the MVC of the triceps-surae muscle (10%; P < 0.05) was observed in response to immobilization. When subjected to running exercise immediately after immobilization, the muscle strength of the triceps-surae muscles dropped even further, but just in the immobilized leg (41%; P < 0.05). The present study highlights the importance of determining the muscle endurance when evaluating the effect of immobilization on muscle parameters.

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Effects of 17-day spaceflight on electrically evoked torque and cross-sectional area of the human triceps surae

Cited by 48 publications

References 30 publications

Effects of 17-day spaceflight on knee extensor muscle function and size

Effects of 17-day spaceflight on knee extensor muscle function and size

Neural activation of the triceps surae is impaired following 2�weeks of immobilization

The influence of training status on the drop in muscle strength after acute exercise

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