Exerciseand Skeletal Muscles with Spaceflight
Theinvestigation was aimed in documenting the result of an exerciseprogram where (n = 9 45 ± 2 yr.) crewmembers were used (Trappe,Scott, etal,1159).This investigation was carried out while these crewmembers wereabroad in the International Space Station for a period of 6 months.
Theinvestigation was aimed in examining the value of one maintaining thecalf muscle characteristics. The focus was on the calf muscle sincethese muscles have been shown to the atrophy compared to the otherleg and the upper muscles of the body. The Magnetic resonance imagingwas used with the aim of obtaining inclusive profile of theirskeletal muscle before their flight and after the flight. MRIassessed the muscle volume, the performance and static (Trappe,Scott, etal,1159).
Therewas the assessment of Calf Muscle Volume, the dynamic calf muscleperformance and static, and the muscle fiber types of the crewmembersbefore and after the event of spaceflight. The crewmembers exerciseregimen varied among them having the aerobic exercise being donehours/ week and this being the moderate intensity while the otherresistance exercise was done at 3–6 days/week. In addition, thisexercise incorporated the multiple exercise of the lower leg (Trappe,Scott, etal,1160).
Thesingle muscle fiber physiology and the report on the musclemicroanatomy are presented as two different reports since there wasno precise protocol, which was followed by all the crewmembers. Inorder to present better perception of this exercise program and theskeletal muscle results each crew member’s exercise and muscle datawere presented.
Theassessment to the crewmembers had begun 6 months before it waslaunched and the testing of the measurements of this crew membersvaried in a slight manner due to this crewmember training processesin Russia and the US. This pretesting procedure took place at JohnsonSpace Center while other three in Kennedy Space Center (Trappe,Scott, etal,1160).There were Ten crewmember who participated in the investigation andone of the crew data was no included since it was not complete. Thesecrewmembers are made up of the American astronauts and the Russiancosmonauts.
Duringthe exercise in space, the crewmembers had an access to thetreadmill, a velocipede and two bicycle ergometers. The treadmillcould be used in both active and passive sessions the bicycleergometer provided a distinctive loading in 1-W increments and couldmove up to 350 W and the feet were secured by clip less pedal(Trappe,Scott, etal,1160).The guideline of the operation required that the crewmembers toexercise up to 2.5 hours while in space with an allocation per dayand this 2.5h included the time of storage, the personal hygiene andhardware setup.
Todetermine the muscle volume contained in calf muscle an MRI wasperformed on this crewmembers few days before their return fromspace. The isokinetic and the maximal voluntary were assessed usingthe torque-velocity dynamometer also used in the assessment ofcontraction of the leg calf muscles (Trappe,Scott, etal,1161).Later the effect of spaceflight on the MRI and the function wasanalyzing by the use of repeated-measure ANOVA for each of the spacecrewmember.
Crewmembersperformed a broad range of anaerobic exercise (treadmill + cycle). Onaverage, About 138 ± 26 min/wk cyclesexercises were completedand approached ∼5h/wk or equivalent∼50min/day. On average, about 138 ± 26 min/wk, cycle exercise werecompleted, which ranged between 10-150W.
Fourcrewmembers (B, A, C and G) used the cycle ergometer ∼81%, ranging between 70% -90% or more days of the mission. Other foursubject F, H, I and D with an average ∼37% ranging from 28-41% were used. Crewmembers E, B, H and G,resulted to a treadmill of high volume (>200 min/wk) of running/walking activities. Another five crewmember, C, A, D, F, and I usedtreadmill of about (≤ 85 min/wk). All the crewmembers’ legexercise consisted of resistance, heel raises and squats. The totalof about 435,000 muscles contraction for every leg was performed. Theresults varied from ∼200,000(for C) and 1 million (for B). A total time spend in orbit was ∼4,248h and constituted ∼3.4%in the exercise program present.
Theprogram resulted to smaller both soleus muscle and gastrocnemius of P< 0.05. After period of six months the result were, the soleus(−15 ± 2%) and gastrocnemius (−10 ± 2%) for pre- to postflight.Crewmember E had −1% atrophy at the end of flight. Crewmember Aand F lost about 20%of calf muscles mass. The rest lost about 10% ofcalf muscle mass.
Gastrocnemiusremained at 5-6% atrophied, which was still insignificant. Soleus hadreduced with an average of −9 ± 1% for all crewmembers. Calfmuscle declined average of −8 ± 2%.
Thecalf muscle performance of crewmember was between (60°/s) slowest,and (180°/s) fastest. MVC reduced to −14 ± 2% at recorded at R+7and at R+13 it was much lower (−13 ± 5% P < 0.05). All thecrewmembers show a decline in MVC ranging between −7 to −22% withflight. Seven crewmembers at R+13 were at range −9 to −33% whilethe rest (A and H) had 5–10%, increase. At isokinetic speed 60°/sabout −20 ± 3% was lost (P < 0.05) and was maintained at −19± 4 P < 0.05 tested at R+13.
MHCprofile was performed on a total of 4,328 for both soleus andgastrocnemius muscle after and before flight including 1,960 musclefibers for the gastrocnemius and 2,368 muscle fibers for 2,368muscle fibers. The result was in MHC I fibers, 12% decrease (P <0.05), MHCI/IIa +4% of hybrid fibers and +9% in MHC IIa fibers. Theaverage decline for seven subjects ranged from−6 to −31%.
Thestudy examined the benefit of regular exercise for the body musclesprotection. The results showed that regular exercise could notprotect the calf muscles completely. Calf muscles performance andmass decrease with fast-to-slow transition fiber-type in both thesoleus and gastrocnemius muscles. This proves that change of exerciserequires full human skeletal muscle protection.
Theexercise program performed by the members showed a significantdisparity in mode and volume of activity and was impacted by externalcontrol. Minimum reambulation resulted from muscle biopsies carriedout at R+0 in a duration of few hours. The result shows that anaverage muscle mass -13% was lost with spaceflight which was lessthat that if the previous period (-17%). The loss muscle counts toabout half of that of long-duration, which shows ∼29%,decrease. However, treadmill exercise proved to provide protection tothe calf muscle.
Bothdynamic and static muscles show a substantial decline in calf muscleperformance with spaceflight. Muscle performance declined more duringthe long –duration bed rest compared to stay in space. Calf muscleslack fiber recovery rapture and decrease can lead to seriousproblems.
Trappe,Scott, et al. "Exercise in space: human skeletal muscle after 6months aboard the International Space Station." Journalof Applied Physiology106.4 (2009): 1159-1168.