| 1. |
- Psilander, Niklas, et al.
(författare)
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Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle
- 2019
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Ingår i: Journal of Applied Physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 126:6, s. 1636-1645
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Tidskriftsartikel (refereegranskat)abstract
- Previously trained mouse muscles acquire strength and volume faster than naive muscles; it has been suggested that this is related to increased myonuclear density. The present study aimed to determine whether a previously strength-trained leg (mem-leg) would respond better to a period of strength training than a previously untrained leg (con-leg). Nine men and 10 women performed unilateral strength training (T1) for 10 wk, followed by 20 wk of detraining (DT) and a 5-wk bilateral retraining period (T2). Muscle biopsies were taken before and after each training period and analyzed for myonuclear number, fiber volume, and cross-sectional area (CSA). Ultrasound and one repetition of maximum leg extension were performed to determine muscle thickness (MT) and strength. CSA (similar to 17%), MT (similar to 10%), and strength (similar to 20%) increased during T1 in the mem-leg. However, the myonuclear number and fiber volume did not change. MT and CSA returned to baseline values during DT, but strength remained elevated (similar to 60%), supporting previous findings of a long-lasting motor learning effect. MT and strength increased similarly in the mem-leg and con-leg during T2, whereas CSA, fiber volume, and myonuclear number remained unaffected. In conclusion, training response during T2 did not differ between the mem-leg and con-leg. However, this does not discount the existence of human muscle memory. since no increase in the number of myonuclei was detected during T1 and no clear detraining effect was observed for cell size during DT; thus, the present data did not allow for a rigorous test of the muscle memory hypothesis. NEW & NOTEWORTHY If a long-lasting intramuscular memory exists in humans. this will affect strength-training advice for both athletes and the public. Based on animal experiments, we hypothesized that such a memory exists and that it is related to the myonuclear number. However, a period of unilateral strength training, followed by detraining, did not increase the myonuclear number. The training response, during a subsequent bilateral retraining period, was not enhanced in the previously trained leg.
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| 2. |
- Andersson, Helena M, et al.
(författare)
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Elite football on artificial turf versus natural grass : movement patterns, technical standards, and player impressions
- 2008
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:2, s. 113-22
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.
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| 3. |
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| 4. |
- Mascher, Henrik, et al.
(författare)
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Changes in signalling pathways regulating protein synthesis in human muscle in the recovery period after endurance exercise
- 2007
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Ingår i: Acta Physiologica. - : Blackwel. - 1748-1708 .- 1748-1716. ; 191:1, s. 67-75
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Exercise induced alterations in the rate of muscle protein synthesis may be related to activity changes in signalling pathways involved in protein synthesis. The aim of the present study was to investigate whether such changes in enzyme phosphorylation occur after endurance exercise. METHODS: Six male subjects performed ergometer cycling exercise for 1 h at 75% of the maximal oxygen uptake. Muscle biopsy samples from the vastus lateralis were taken before, immediately after, 30 min, 1 h, 2 h and 3 h after exercise for the determination of protein kinase B (PKB/Akt), mammalian target of rapamycin (mTOR), glycogen synthase 3 kinase (GSK-3), p70S6 kinase (p70(S6k)) and eukaryotic elongation factor 2 (eEF2) phosphorylation. RESULTS: The phosphorylation of Akt was unchanged directly after exercise, but two- to fourfold increased 1 and 2 h after the exercise, whereas GSK-3alpha and beta phosphorylation were two- to fourfold elevated throughout most of the 3-h recovery period. Phosphorylation of mTOR was elevated threefold directly after, 30 min and 2 h after exercise and eEF2 phosphorylation was decreased by 35-75% from 30 min to 3 h-recovery. Exercise led to a five- to eightfold increase in Ser(424)/Thr(421) phosphorylation of p70(S6k) up to 30 min after exercise, but no change in Thr(389) phosphorylation. CONCLUSIONS: The marked decrease in eEF2 phosphorylation suggests an activation of translation elongation and possibly protein synthesis in the recovery period after sustained endurance exercise. The lack of p70(S6k) activation suggests that translation initiation is activated via alternative pathways, possibly via the activation of eukaryotic initiating factor 2B.
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| 5. |
- Björkman, Frida, et al.
(författare)
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Regular moist snuff dipping does not affect endurance exercise performance
- 2017
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 12:7
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Tidskriftsartikel (refereegranskat)abstract
- Physiological and medical effects of snuff have previously been obtained either in cross-sectional studies or after snuff administration to non-tobacco users. The effects of snuff cessation after several years of daily use are unknown. 24 participants with >2 years of daily snuff-use were tested before and after >6 weeks snuff cessation (SCG). A control group (CO) of 11 snuff users kept their normal habits. Resting heart rate (HR) and blood pressure (BP) were significantly lower in SCG after snuff cessation, and body mass was increased by 1.4 +/- 1.7 kg. Total cholesterol increased from 4.12 +/- 0.54 (95% CI 3.89-4.35) to 4.46 +/- 0.70 (95% CI 4.16-4.75) mM L-1 in SCG, due to increased LDL, and this change was significantly different from CO. Resting values of HDL, C-reactive protein, and free fatty acids (FFA) remained unchanged in both groups. In SCG group, both HR and BP were reduced during a four-stage incremental cycling test (from 50 to 80% of VO(2)max) and a prolonged cycling test (60 min at 50% of VO(2)max). Oxygen uptake (VO2), respiratory exchange ratio, blood lactate (bLa) and blood glucose (bGlu) concentration, and rate of perceived exertion (RPE) were unchanged. In CO group, all measurements were unchanged. During the prolonged cycling test, FFA was reduced, but with no significant difference between groups. During the maximal treadmill running test peak values of VO2, pulmonary ventilation (VE), time to exhaustion and bLa were unchanged in both groups. In conclusion, endurance exercise performance (VO(2)dmax and maximal endurance time) does not seem to be affected by prolonged snuff use, while effects on cardiovascular risk factors are contradictory. HR and BP during rest and submaximal exercise are reduced after cessation of regular use of snuff. Evidently, the long-time adrenergic stress on circulation is reversible.
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| 6. |
- Pettersson, Stefan, 1972, et al.
(författare)
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Six Weeks of Aerobic Exercise in Untrained Men With Overweight/Obesity Improved Training Adaptations, Performance and Body Composition Independent of Oat/Potato or Milk Based Protein-Carbohydrate Drink Supplementation.
- 2021
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Ingår i: Frontiers in Nutrition. - : Frontiers Media S.A.. - 2296-861X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: Protein availability around aerobic exercise might benefit aerobic capacity and body composition in normal weight adults. However, it is unknown if individuals with overweight/obesity elicit similar adaptations or improve other cardiometabolic/health-related markers in response to different types of protein. Thus, our aim was to study the effect of supplementation of two different protein drinks in conjunction with exercise on aerobic capacity, body composition and blood health markers in untrained subjects with overweight or obesity. Methods: The present study measured training adaptation and health parameters over a 6 week period in untrained men with overweight/obesity (n = 28; BMI 30.4 ± 2.2 kg/m2) ingesting either plant- (Oat/Potato; n = 8) or animal-based (Milk; n = 10) protein-carbohydrate drinks (10 g of protein/serving), or a control carbohydrate drink (n = 10) acutely before and after each training session (average three sessions/week @ 70% HRmax). Pre-post intervention ˙VO2peakV˙O2peak , muscle biopsies and blood samples were collected, body composition measured (DXA) and two different exercise tests performed. Body weight was controlled with participants remaining weight stable throughout the intervention. Results: For the groups combined, the training intervention significantly increased ˙VO2peakV˙O2peak (8%; P < 0.001), performance in a time-to-exhaustion trial (~ 100%; P < 0.001), mitochondrial protein content and enzyme activity (~20-200%). Lean body mass increased (1%; P < 0.01) and fat mass decreased (3%; P < 0.01). No significant effects on fasting blood glucose, insulin, lipids or markers of immune function were observed. There were no significant interactions between drink conditions for training adaptation or blood measurements. For body composition, the Oat/Potato and carbohydrate group decreased leg fat mass significantly more than the Milk group (interaction P < 0.05). Conclusions: Aerobic capacity and body composition were improved and a number of mitochondrial, glycolytic and oxidative skeletal muscle proteins and enzyme activities were upregulated by a 6 week training intervention. However, none of the parameters for endurance training adaptation were influenced by protein supplementation before and after each training session.
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| 7. |
- Ekblom, Björn, et al.
(författare)
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Studier av stridsvärde vid långvarigt arbete - Sammanfattning och reflektioner : Rapport 9.
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den militärmedicinska forskningsgruppen vid Åstrandlaboratoriet, Gymnastik- och Idrottshögskolan, Stockholm, har som forskningsuppgift med stöd från Försvarsmakten att studera och föreslå insatser för att upprätthålla stridsvärdet för trupp under långvarigt fysiskt arbete. Forskningen har hitintills resulterat i åtta rapporter, där fysisk arbetsförmåga studerats under olika förhållanden. Föreliggande rapport sammanfattar de huvudsakliga resultaten från dessa undersökningar men omfattar också en diskussion gällande skillnader och likheter mellan kvinnors jämfört med mäns adaptation till långvarigt och tungt arbete samt ett kort avsnitt om fortsatta undersökningar, byggda på tidigare resultat.
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| 8. |
- Flockhart, Mikael, et al.
(författare)
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Slutövning GMU: ”Aldrig ge upp”, Amf1, Berga örlogsbas. : Rapport 4.
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Energistatus och förändring i fysiskt stridsvärde studerades i samband med en nästan 8 dygn långa grundmilitär slutövning (GMU) vid AMF-1 Berga Örlogsskolor i månadsskiftet oktober november 2013.Totalt deltog 105 soldater i övningen, fördelat på 3 plutoner om vardera 35 soldater. En subgrupp på 24 soldater (8 kvinnor) bestående av 8 soldater från vardera pluton studerades mer ingående.Medelhjärtfrekvensen för de 6 soldater (2 kvinnor) som hade i stort sett kompletta mätningar från den 187 timmar långa övningen, inklusive viloperioder, var 88 ± 7 slag/minut. Utifrån hjärtfrekvensdata beräknades den totala energiomsättningen till i genomsnitt 44 000 ± 6 600 kcal, vilket motsvarar 5 600 ± 840 kcal per dygn och 235 ± 35 kcal/tim. Total energiförbrukning var i genomsnitt 39 000 kcal för kvinnorna och 46 500 kcal för männen. I övrigt noterades inte några betydande skillnader mellan kvinnor och män. Däremot var det stora individuella variationer i energiutgift, vilka till ca hälften berodde på skillnader i kroppsvikt. Med hänsyn till kroppsvikt och buren vikt var energiförbrukningen ca 3,1 ± 0,23 kcal per timme per kg totalvikt. Den individuella variationen beror på skillnad i buren vikt, på olika uppgifter och på individuella fysiologiska skillnader.Utifrån beräknat energiintag blev det totala energiunderskottet under övningen 12 000-15 000 kcal, vilket är ca 1 500-2 000 kcal per dygn. Viktminskningen under övningen var 2,9 kg för kvinnor och 3,7 kg för män. Denna viktminskning på >4 % leder troligen till försämrad uthållighetsförmåga.Den maximala muskelstyrkan i armar och ben var i stort sett oförändrade efter övningen, liksom den beräknade maximala syreupptagningsförmågan. Däremot upplevdes ett lågintensivt cykelarbete som betydligt tyngre efter övningen. Muskeluthållighet mättes inte i denna studie.Ett skjutprov om 5 skott i liggande på 100 m mot en tredjedelsfigur visade 64 deltagande soldater på en försämrad träffprocent från 90,5% före till 79,4 % efter övningen. Alla soldater hade minst en träff före medan 6 soldater hade alla bom efter övningen.Slutsatsen från studien är att GMU-övningen resulterade i ett stort energiunderskott. Stridsvärdet, bedömt från skjutprovet var klart försämrat. Maximala fysiologiska parametrar var i stort sett oförändrade, medan skattad ansträngning och därmed uthållighetsförmåga, försämrades.
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| 9. |
- Godhe, Manne, et al.
(författare)
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Att bära tungt - en fysiologisk analys: Kvinnor : Rapport 8.
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sjutton kvinnliga vältränade försökspersoner, åtta stycken med vana att bära tungt och nio stycken utan sådan vana, genomförde gång på löpband och mjukt underlag i hastigheterna 3 och 5 km/tim med bärvikter i ryggsäck på 20, 35 och 50 kg.Mjukt underlag i form av blå gymnastikmattor, indikerande gång i lätt terräng, ökade energiomsättningen under både hastigheterna mellan 10 och 15 %, jämfört med hårt underlag (löpband) med en grads lutning. Energiomsättningen ökade i genomsnitt lika mycket med ökad hastighet som med ökad bärvikt. Den individuella variationen vid en given bärvikt och hastighet är mycket stor. Beroende på bärvikt och hastighet kan energiomsättningen variera med 100 %. Dessa stora variationer i energiomsättning bör uppmärksammas vid beräkning av energitilldelning via kosten vid längre militära operationer.Energiomsättningen vid tyngsta belastningen – 50 kilo bärvikt och hastigheten 5 km/tim – belastade försökspersonerna på i genomsnitt 57 % av maximal syreupptagningsförmåga. I individuella fall var belastningen 72 % av maximal syreupptagningsförmåga. Dessa höga belastningar är oacceptabelt höga för transporter under längre tid och kan vara en orsak till belastningsskador.Förmågan att bära tungt sammanfaller med ökad kroppsvikt och benmuskelstyrka. Bärförmåga för mindre vikter, högst 35 kg, sammanfaller inte med någon av ovanstående faktorer. Således, för tyngre bärvikter vid förflyttningar bör selektion av soldater ske enligt de uppmätta parametrarna, medan vad gäller lättare vikter föreligger inte samma selektionskriterier.En slutsats från resultaten av denna undersökning är den ursprungliga uttagningen till tunga arbetsuppgifter inom försvaret bör genomföras med tunga arbetsbelastningar, motsvarande de i denna undersökning. I kommande rapport sammanfattas studierna på män och kvinnors bärförmåga, likheter och olikheter mellan könen, möjliga selektionskriterier samt rekommendationer med utgångspunkt från genomförda undersökningar och resultat från olika andra undersökningar.
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| 10. |
- Cardinale, Daniele A., 1982-, et al.
(författare)
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Superior Intrinsic Mitochondrial Respiration in Women Than in Men.
- 2018
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Sexual dimorphism is apparent in humans, however, to date no studies have investigated mitochondrial function focusing on intrinsic mitochondrial respiration (i.e., mitochondrial respiration for a given amount of mitochondrial protein) and mitochondrial oxygen affinity (p50mito) in relation to biological sex in human. A skeletal muscle biopsy was donated by nine active women, and ten men matched for maximal oxygen consumption (VO2max) and by nine endurance trained men. Intrinsic mitochondrial respiration, assessed in isolated mitochondria, was higher in women compared to men when activating complex I (CIP) and complex I+II (CI+IIP) (p < 0.05), and was similar to trained men (CIP, p = 0.053; CI+IIP, p = 0.066). Proton leak and p50mito were higher in women compared to men independent of VO2max. In conclusion, significant novel differences in mitochondrial oxidative function, intrinsic mitochondrial respiration and p50mito exist between women and men. These findings may represent an adaptation in the oxygen cascade in women to optimize muscle oxygen uptake to compensate for a lower oxygen delivery during exercise.
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