| 1. |
- Norrbrand, Lena
(författare)
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Acute and early chronic responses to resistance exercise using flywheel or weights
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Resistance exercise using weights typically offers constant external load during coupled shortening (concentric) and lengthening (eccentric) muscle actions in sets of consecutive repetitions until failure. However, the constant external load and the inherent capability of skeletal muscle to produce greater force in the eccentric compared with the concentric action, would infer that most actions are executed with incomplete motor unit involvement. In contrast, use of the inertia of flywheels to generate resistance allows for maximal voluntary force to be produced throughout the concentric action, and for brief episodes of greater eccentric than concentric loading, i.e. “eccentric overload”. Thus, it was hypothesized that acute flywheel resistance exercise would induce greater motor unit and muscle use, and subsequent fatigue, compared with traditional weight stack/free weight resistance exercise. Furthermore, it was hypothesized that flywheel training would induce more robust neuromuscular adaptations compared with training using weights. A total of 43 trained and untrained men were investigated in these studies.Knee extensor muscle activation, fatigue response and muscle use were assessed during exercises by recording electromyographic signals and by means of functional magnetic resonance imaging, respectively. Flywheel resistance exercise provoked maximal or near maximal muscle activation from the first repetition, induced robust fatigue, and prompted more substantial motor unit and muscle use than weight stack/free weight resistance exercise in both novice and resistance trained men. Both prior to and following five weeks of unilateral knee extension training, the eccentric muscle activation was greater with flywheel than weight stack training. Furthermore, weight stack training generated greater increases of dynamic strength and neural adaptations, while flywheel training generated more prominent hypertrophy of individual quadriceps muscles and greater improvement of maximal isometric strength. Hence, due to the preferential metabolic cost of the concentric rather than eccentric actions, the maximal activation through the entire range of the concentric action within each repetition of a set during flywheel resistance exercise probably evoked the marked fatigue, and prompted more substantial muscle use than resistance exercise using weights. Furthermore, while any cause‐effect relationship remains to be determined, results of the pesent study suggest that brief episodes of “eccentric overload” amplify muscular adaptations following concentriceccentric resistance training.
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| 2. |
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| 3. |
- Aagaard, Per, 1957, et al.
(författare)
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Early repolarization in ECG. Definition, prevalence and prognostic significance
- 2015
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Ingår i: Läkartidningen. - 0023-7205. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- Early repolarization defined as antero-lateral ST-segment elevation exists in 1-2 % of the general population and has been considered a benign ECG finding for decades. However, early repolarization, defined as infero-lateral J-waves, has in recent studies been associated with an increased - albeit low - risk of sudden and cardiovascular death. This ECG pattern is present in 3-13% of the general population. However, exercise training can induce all types of early repolarization, and the prevalence in the athletic population rises to 20-90%. There is large variability between sports (higher in endurance athletes) and also throughout the season (higher during times of peak fitness). In athletes, early repolarization, regardless of type, is considered benign. In asymptomatic non-athletes, the absolute risk is too low to use this ECG finding in clinical practice. In individuals with J-wave syndrome, on the other hand, ICD implantation should be strongly considered to prevent sudden cardiac death.
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| 4. |
- Aagaard, Per, 1957, et al.
(författare)
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Heart Rate and Its Variability in Response to Running-Associations with Troponin
- 2014
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Ingår i: Medicine and Science in Sports and Exercise. - : Ovid Technologies (Wolters Kluwer Health). - 0195-9131. ; 46:8, s. 1624-1630
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The objective of this study is to investigate the time course of autonomic tone changes after a first-time endurance running race participation and associations with postexertional high-sensitivity troponin (hsTnT) levels in middle-aged males. Methods: Male (n = 42) first-time long-distance running race (Lidingoloppet 30 km) participants >= 45 yr (50.5 +/- 5) were examined. HR and HR variability (HRV) in the time domain (SDANN) was measured continuously from 2 d before to 4 d after the race using a wireless cardiovascular monitor that also recorded arrhythmia episodes. In addition, subjects were assessed pre- and postrace by medical history and physical examination, 12-lead ECG, blood tests including hsTnT, and echocardiography. Results: Compared with corresponding prerace values, nighttime (2: 00-4: 00 a.m.) HR was significantly elevated (63.6 +/- 9.4 vs 53.9 +/- 8.3 bpm, P < 0.001) on the first night postrace, whereas HRV remained reduced for a median of 64 h (interquartile range, 51-102 h). A prolonged HR recovery period (r = 0.48, P = 0.005) and a larger reduction in postrace HRV (r = -0.49, P = 0.003) correlated with higher postrace hsTnT levels. The association between reduced HRV and higher hsTnT remained significant after multivariate analysis (A = -0.48, P = 0.01). No sustained ventricular arrhythmias were recorded, but atrial fibrillation occurred in two subjects. Conclusion: Endurance running race participation caused a prolonged alteration of autonomic tone. More marked and prolonged changes were associated with higher levels of hsTnT, suggesting that the magnitude of troponin increase after strenuous exercise may reflect the magnitude of exercise-induced cardiovascular stress.
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| 5. |
- Aagaard, Per, 1957, et al.
(författare)
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Preparticipation Evaluation of Novice, Middle-Age Long-Distance Runners.
- 2013
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Ingår i: Medicine and science in sports and exercise. - 0195-9131 .- 1530-0315. ; 45:1, s. 130-137
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Tidskriftsartikel (refereegranskat)abstract
- Abstract PURPOSE: To assess the cardiovascular health and risk profile in middle-aged males making an entry to participate for their first time in a long-distance race. METHODS: Male first-time participants ≥45 years in the world's largest cross-country running race, the Lidingöloppet, were evaluated with a medical history and physical exam, European risk-SCORE, 12-lead ECG, echocardiography and blood tests. Further diagnostic work-up was performed when clinically indicated. RESULTS: Of 265 eligible runners, 153 (58%, age 51±5 y) completed the study. While the 10-year fatal cardiovascular event risk was low (SCORE: 1% (IQR: 0 - 1%)), mild abnormalities were common, e.g. elevated blood-pressure (19%), left ventricular hypertrophy (6%), elevated LDL cholesterol (5%). ECG changes compatible with "athlete's heart" were present in 82%, e.g. sinus bradycardia (61%) and/or early repolarization (32%). ECG changes considered training-unrelated were found in 24%, e.g. prolonged QTc: 13%; left axis deviation: 5.3%; left atrial enlargement: 4%). In 14 runners (9%) additional diagnostic work-up was clinically motivated, and 4 (2%) were ultimately discouraged from vigorous exercise due to QTc intervals >500 ms (n=2), symptomatic atrioventricular block (n=1), and a cardiac tumor (n=1). The physician exam and the ECG identified 12 of the 14 subjects requiring further evaluation. CONCLUSIONS: Cardiovascular evaluation of middle-aged men, including a physician exam and a 12-lead ECG, appears useful to identify individuals requiring further testing prior to vigorous exercise. The additional yield of routine echocardiography was small.
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| 6. |
- Bojsen-Møller, Jens, et al.
(författare)
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Differential displacement of the human soleus and medial gastrocnemius aponeuroses during isometric plantar flexor contractions in vivo.
- 2004
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Ingår i: Journal of applied physiology (Bethesda, Md. : 1985). - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 97:5, s. 1908-14
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Tidskriftsartikel (refereegranskat)abstract
- The human triceps surae muscle-tendon complex is a unique structure with three separate muscle compartments that merge via their aponeuroses into the Achilles tendon. The mechanical function and properties of these structures during muscular contraction are not well understood. The purpose of the study was to investigate the extent to which differential displacement occurs between the aponeuroses of the medial gastrocnemius (MG) and soleus (Sol) muscles during plantar flexion. Eight subjects (mean +/- SD; age 30 +/- 7 yr, body mass 76.8 +/- 5.5 kg, height 1.83 +/- 0.06 m) performed maximal isometric ramp contractions with the plantar flexor muscles. The experiment was performed in two positions: position 1, in which the knee joint was maximally extended, and position 2, in which the knee joint was maximally flexed (125 degrees ). Plantarflexion moment was assessed with a strain gauge load cell, and the corresponding displacement of the MG and Sol aponeuroses was measured by ultrasonography. Differential shear displacement of the aponeurosis was quantified by subtracting displacement of Sol from that of MG. Maximal plantar flexion moment was 36% greater in position 1 than in position 2 (132 +/- 20 vs. 97 +/- 11 N.m). In position 1, the displacement of the MG aponeurosis at maximal force exceeded that of the Sol (12.6 +/- 1.7 vs. 8.9 +/- 1.5 mm), whereas in position 2 displacement of the Sol was greater than displacement of the MG (9.6 +/- 1.0 vs. 7.9 +/- 1.2 mm). The amount and "direction" of shear between the aponeuroses differed significantly between the two positions across the entire range of contraction, indicating that the Achilles tendon may be exposed to intratendinous shear and stress gradients during human locomotion.
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| 7. |
- Elam, Cecilia, et al.
(författare)
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Effects of age on muscle power, postural control and functional capacity after short-term immobilization and retraining.
- 2022
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Ingår i: Journal of musculoskeletal & neuronal interactions. - 1108-7161. ; 22:4, s. 486-497
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of lower limb immobilization and retraining on postural control and muscle power in healthy old and young men.Twenty men, nine old (OM:67.3±4.4 years) and eleven young (YM:24.4±1.6 years) underwent 2 weeks of unilateral whole-leg casting, followed by 4 weeks of retraining. Measures included center of pressure (CoP) sway length and area during single- and double-leg stance, maximal leg extensor muscle power, habitual and maximal 10-m gait speed, sit-to-stand performance, and 2-min step test.After immobilization, leg extension muscle power decreased by 15% in OM (from 2.68±0.60 to 2.29±0.63 W/kg, p<0.05) and 17% in YM (4.37±0.76 to 3.63±0.69 W/kg, p<0.05). Double-leg CoP sway area increased by 45% in OM (218±82 to 317±145 mm2; p<0.05), with no change in YM (p=0.43). Physical function did not change after immobilization but sit-to-stand performance (+20%, p<0.05) and 2-min step test (+28%, p<0.05) increased in OM following retraining. In both groups, all parameters returned to baseline levels after retraining.Two weeks of lower limb immobilization led to decreases in maximal muscle power in both young and old, whereas postural control was impaired selectively in old men. All parameters were restored in both groups after 4 weeks of resistance-based retraining.
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| 8. |
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| 9. |
- Elam Edwén, Cecilia, 1970, et al.
(författare)
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Stretch-shortening cycle muscle power in women and men aged 18-81 years: Influence of age and gender
- 2014
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Ingår i: Scandinavian Journal of Medicine & Science in Sports. - : Wiley. - 0905-7188. ; 24:4, s. 717-726
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Tidskriftsartikel (refereegranskat)abstract
- This study explored the age-related deterioration in stretch-shortening cycle (SSC) muscle power and concurrent force-velocity properties in women and men across the adult life span. A total of 315 participants (women: n = 188; men: n = 127) aged 18-81 years performed maximal countermovement jumps on an instrumented force plate. Maximal SSC leg extension power expressed per kg body mass (Ppeak) was greater in men than in women across the adult age span (P < 0.001); however, this gender difference was progressively reduced with increasing age, because men showed an similar to 50% faster rate of decline in SSC power than women (P < 0.001). Velocity at peak power (VPpeak) was greater in men than in women (P < 0.001) but declined at a greater rate in men than in women (P = 0.002). Vertical ground reaction force at peak power (FPpeak) was higher in men than in women in younger adults only (P < 0.001) and the age-related decline was steeper in men than in women (P < 0.001). Men demonstrated a steeper rate of decline in Ppeak than women with progressive aging. This novel finding emerged as a result of greater age-related losses in men for both force and velocity. Consequently, maximal SSC power production was observed to converge between genders when approaching old age.
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| 10. |
- Estmark Kalinowski, Birgitta
(författare)
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Dissolution Kinetics and Alteration Products of Micas and Epidote in Acidic Solutions at Room Temperature
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The reaction kinetics of the weathering of several phyllosilicates and one sorosilicate were stud ied experimentally. The alteration products were characterised by various methods in clud ing XRD, HRTEM, SEM, FTIR, NMR and Mössbauer spectroscopy. Weathering of silicates is of particular concern to our knowledge of several areas in low temperature geochemistry, such as el e ment cy cling, ground water chemistry and soil formation. The importance of these processes ex tends to the long-term nutrient supply to forest ecosystems and control of soil and water acidity, es pe cial ly in Scandinavia.Several soil models designed to predict the impact of acid rain on the soil chemistry rely on kinetic data of mineral weathering. The reaction kinetics for minerals are used in such models to predict chang es in soil chem is try. This enables calculation of the effect of acid rain (i. e. critical load) in a 100-year per spec tive. For some minerals relatively little knowledge is available for the reaction kinetics. There fore the dissolution kinetics of muscovite, biotite, phlogopite, vermiculite and epi dote were studied over the pH range 1 to 6.5 at room temperature using flow-through reactors.Silica release rates based on specific surface area are about the same for as divers silicates as epidote (sorosilicate), K-feldspar (tectosilicate) and phlogopite (phyllosilicate). At pH 3 log R = -15.41, -15.5 and -15.46 respectively for these min er als. However, the framework of Si and Al is likely to determine with what ease cations positioned in between the conformation of Si and Al tetrahedra are re leased. For example, K in micas have transportation channels due to the layer struc ture and ought there fore to be released easier than in K-feldspar. In most cases Si is the most slowly released element in silicates, but in epidote, Si and Ca are the fastest released elements from the structure, while Al and Fe are retained. Leaching of inter framework cations creates strain and charge im bal ance in the silicate structure, causing Si to be more readily released in base cation containing silicates than in quartz. Released Si may repolymerise directly at the surface of silicates or interlayers. Amor phous silica gel has been detected, as a weathering product between packages of 2:1 layers in bi otite, using AEM. Iron(hydr)oxides have been found as the end-product of biotite weathering. Re sid u al layer calculations based on the solution composition show that Al and Fe form an enriched layer with a thickness of 1-2 nm at the surface of epidote.Biotite and phlogopite probably alter to trioctahedral vermiculite from the edges and inwards. Mössbauer spectroscopy shows that weathering of biotite as well as ver micu lite is accompanied by oxidation. Al-hydroxy polymers are introduced in the in ter lay er during weathering of phlogopite and vermiculite, which is supported by both XRD and 27Al MAS-NMR analyses. Additions of KCl and AlCl3 to the reactant solutions show that release rates, exfoliation and oxidation processes decrease with increased concentrations for both biotite and phlogopite. Leaching of interlayer cat i ons seems thus to initiate oxidation of ferrous iron.
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| 11. |
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| 12. |
- Hvid, Lars G., et al.
(författare)
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Myosin content of single muscle fibers following short-term disuse and active recovery in young and old healthy men
- 2017
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Ingår i: Experimental Gerontology. - : Elsevier BV. - 0531-5565 .- 1873-6815. ; 87:Part A, s. 100-107
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Tidskriftsartikel (refereegranskat)abstract
- Short-term disuse and subsequent recovery affect whole muscle and single myofiber contractile function in young and old. While the loss and recovery of single myofiber specific force (SF) following disuse and rehabilitation has been shown to correlate with alterations in myosin concentrations in young, it is unknown whether similar relationships exist in old. Therefore, the purpose of the present study was to examine the effect of 14 days lower limb disuse followed by 28 days of active recovery on single muscle fiber myosin content in old (68 yrs) and young (24 yrs) recreationally physically active healthy men. Following disuse, myosin content decreased (p < 0.05) in MHC 1 (young − 28%, old − 19%) and 2a fibers (young − 23%, old − 32%). In old, myosin content decreased more (p < 0.05) in MHC 2a vs 1 fibers. Following recovery, myosin content increased (p < 0.05) and returned to pre-disuse levels for both young and old in both fiber types, with MHC 2a fibers demonstrating an overshooting in young (+ 31%, p < 0.05) but not old. Strong correlations were observed between myosin content and single fiber SF in both young and old, with greater slope steepness in MHC 2a vs 1 fibers indicating an enhanced intrinsic contractile capacity of MHC 2a fibers. In conclusion, adaptive changes in myofiber myosin content appear to occur rapidly following brief periods of disuse (2 wks) and after subsequent active recovery (4 wks) in young and old, which contribute to alterations in contractile function at the single muscle fiber level. Changes in myosin content appear to occur independently of age, while influenced by fiber type (MHC isoform) in young but not old.
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| 13. |
- Hvid, Lars G., et al.
(författare)
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Plasticity in central neural drive with short-term disuse and recovery - effects on muscle strength and influence of aging
- 2018
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Ingår i: Experimental Gerontology. - : Elsevier BV. - 0531-5565 .- 1873-6815. ; 106, s. 145-153
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Tidskriftsartikel (refereegranskat)abstract
- While short-term disuse negatively affects mechanical muscle function (e.g. isometric muscle strength) little is known of the relative contribution of adaptions in central neural drive and peripheral muscle contractility. The present study investigated the relative contribution of adaptations in central neural drive and peripheral muscle contractility on changes in isometric muscle strength following short-term unilateral disuse (4 days, knee brace) and subsequent active recovery (7 days, one session of resistance training) in young (n = 11, 24 yrs) and old healthy men (n = 11, 67 yrs). Maximal isometric knee extensor strength (MVC) (isokinetic dynamometer), voluntary muscle activation (superimposed twitch technique), and electrically evoked muscle twitch force (single and doublet twitch stimulation) were assessed prior to and after disuse, and after recovery. Following disuse, relative decreases in MVC did not differ statistically between old (16.4 ± 3.7%, p < 0.05) and young (−9.7 ± 2.9%, p < 0.05) (mean ± SE), whereas voluntary muscle activation decreased more (p < 0.05) in old (−8.4 ± 3.5%, p < 0.05) compared to young (−1.1 ± 1.0%, ns) as did peak single (−25.8 ± 6.6%, p < 0.05 vs −7.6 ± 3.3%, p < 0.05) and doublet twitch force (−23.2 ± 5.5%, p < 0.05 vs −2.0 ± 2.6%, ns). All parameters were restored in young following 7 days recovery, whereas MVC and peak twitch force remained suppressed in old. Regression analysis revealed that disuse-induced changes in MVC relied more on changes in single twitch force in young (p < 0.05) and more on changes in voluntary muscle activation in old (p < 0.05), whereas recovery-induced changes in MVC mainly were explained by gains in voluntary muscle activation in both young and old. Altogether, the present data demonstrate that plasticity in voluntary muscle activation (~central neural drive) is a dominant mechanism affecting short-term disuse- and recovery-induced changes in muscle strength in older adults.
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| 14. |
- Krustrup, P., et al.
(författare)
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Effects of recreational football on women's fitness and health: adaptations and mechanisms
- 2018
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 118:1, s. 11-32
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Tidskriftsartikel (refereegranskat)abstract
- The review describes the fitness and health effects of recreational football in women aged 18-65 years. The review documents that 2×1 h of recreational football training for 12-16 weeks causes marked improvements in maximal oxygen uptake (5-15%) and myocardial function in women. Moreover, mean arterial blood pressure was shown to decrease by 2-5 mmHg in normotensive women and 6-8 mmHg in hypertensive women. This review also show that short-term (<4 months) and medium-term (4-16 months) recreational football training has major beneficial impact on metabolic health profile in women, with fat losses of 1-3 kg and improvements in blood lipid profile. Lastly, 2×1 h per week of recreational football training for women elevates lower extremity bone mineralisation by 1-5% and whole-body bone mineralization by 1-2% within 4-12-month interventions. These training adaptations are related to the high heart rates, high number of fast runs, and multiple changes of direction and speed occurring during recreational football training for untrained women. In conclusion, regular small-sided football training for women is an intense and versatile type of training that combines elements of high-intensity interval training (HIIT), endurance training and strength training, thereby providing optimal stimuli for cardiovascular, metabolic and musculoskeletal fitness. Recreational football, therefore, seems to be an effective tool for prevention and treatment of lifestyle diseases in young and middle-aged women, including hypertension, type 2 diabetes and osteopenia. Future research should elucidate effects of football training for elderly women, and as treatment and rehabilitation of breast cancer patients and other women patient groups.
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| 15. |
- Mackey, Abigail L., et al.
(författare)
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Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication
- 2016
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Ingår i: The FASEB Journal. - Bethesda, USA : Federation of American Societies for Experimental Biology. - 0892-6638 .- 1530-6860. ; 30:6, s. 2266-2281
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Tidskriftsartikel (refereegranskat)abstract
- With this study we investigated the role of nonsteroidal anti-inflammatory drugs (NSAIDs) in human skeletal muscle regeneration. Young men ingested NSAID [1200 mg/d ibuprofen (IBU)] or placebo (PLA) daily for 2 wk before and 4 wk after an electrical stimulation-induced injury to the leg extensor muscles of one leg. Muscle biopsies were collected from the vastus lateralis muscles before and after stimulation (2.5 h and 2, 7, and 30 d) and were assessed for satellite cells and regeneration by immunohistochemistry and real-time RT-PCR, and we also measured telomere length. After injury, and compared with PLA, IBU was found to augment the proportion of ActiveNotch1(+) satellite cells at 2 d [IBU, 29 ± 3% vs. PLA, 19 ± 2% (means ± sem)], satellite cell content at 7 d [IBU, 0.16 ± 0.01 vs. PLA, 0.12 ± 0.01 (Pax7(+) cells/fiber)], and to expedite muscle repair at 30 d. The PLA group displayed a greater proportion of embryonic myosin(+) fibers and a residual ∼2-fold increase in mRNA levels of matrix proteins (all P < 0.05). Endomysial collagen was also elevated with PLA at 30 d. Minimum telomere length shortening was not observed. In conclusion, ingestion of NSAID has a potentiating effect on Notch activation of satellite cells and muscle remodeling during large-scale regeneration of injured human skeletal muscle.-Mackey, A. L., Rasmussen, L. K., Kadi, F., Schjerling, P., Helmark, I. C., Ponsot, E., Aagaard, P., Durigan, J. L. Q., Kjaer, M. Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication.
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| 16. |
- Merid, Simon Kebede, et al.
(författare)
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Epigenome-wide meta-analysis of blood DNA methylation in newborns and children identifies numerous loci related to gestational age
- 2020
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Ingår i: Genome Medicine. - Stockholm : Karolinska Institutet, Dept of Clinical Science and Education, Södersjukhuset. - 1756-994X.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Preterm birth and shorter duration of pregnancy are associated with increased morbidity in neonatal and later life. As the epigenome is known to have an important role during fetal development, we investigated associations between gestational age and blood DNA methylation in children. Methods: We performed meta-analysis of Illumina's HumanMethylation450-array associations between gestational age and cord blood DNA methylation in 3648 newborns from 17 cohorts without common pregnancy complications, induced delivery or caesarean section. We also explored associations of gestational age with DNA methylation measured at 4-18 years in additional pediatric cohorts. Follow-up analyses of DNA methylation and gene expression correlations were performed in cord blood. DNA methylation profiles were also explored in tissues relevant for gestational age health effects: fetal brain and lung. Results: We identified 8899 CpGs in cord blood that were associated with gestational age (range 27-42 weeks), at Bonferroni significance, P < 1.06 × 10- 7, of which 3343 were novel. These were annotated to 4966 genes. After restricting findings to at least three significant adjacent CpGs, we identified 1276 CpGs annotated to 325 genes. Results were generally consistent when analyses were restricted to term births. Cord blood findings tended not to persist into childhood and adolescence. Pathway analyses identified enrichment for biological processes critical to embryonic development. Follow-up of identified genes showed correlations between gestational age and DNA methylation levels in fetal brain and lung tissue, as well as correlation with expression levels. Conclusions: We identified numerous CpGs differentially methylated in relation to gestational age at birth that appear to reflect fetal developmental processes across tissues. These findings may contribute to understanding mechanisms linking gestational age to health effects.
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| 17. |
- Michalsik, Lars B, 1960, et al.
(författare)
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Match Performance and Physiological Capacity of Female Elite Team Handball Players.
- 2014
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Ingår i: International Journal of Sports Medicine. - : Georg Thieme Verlag KG. - 0172-4622 .- 1439-3964. ; 35:7, s. 595-607
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Tidskriftsartikel (refereegranskat)abstract
- The present study evaluated the physical demands imposed on female elite team handball players in relation to playing position. Female elite team handball field players were examined during match-play over a 5-year period using video based computerized locomotion analysis of tournament matches. In addition, physiological measurements during match-play and in separate physical tests were carried out. A total distance of 4002±551m (group means±SD) was covered per match with a total effective playing time of 50:42±5:50min:s, while full-time players covered 4693±333m. On average, each player (n=83) performed 663.8±99.7 activity changes per match, and the mean speed was 5.31±0.33km·h−1. High-intensity running constituted 0.8±0.5% of total effective playing time per match corresponding to 2.5±1.8% of the total distance covered. The amount of high-intensity running was reduced (p<0.05) 21.9% in the second half (44.9±16.8m) compared to the first (57.5±21.3m). Maximal oxygen uptake (VO2-max) was 3.49±0.37l O2·min−1 corresponding to 49.6±4.8ml O2·min−1·kg−1. Mean relative workload during match-play was 79.4±6.4% of VO2-max. Mean total running distance in the Yo-Yo intermittent recovery test (level 1) was 1436±222m, which was greater in wing players (1516±172m, p<0.05) than pivots (1360±118m) and backcourt players (1352±148m). In conclusion, modern female elite team handball is a physically demanding intermittent team sport, where players are exposed to high relative workloads with substantial estimated aerobic energy expenditure interspersed by short periods of dominant anaerobic energy production as reflected by the limited amount of high-intensity running. Indications of fatigue and a resulting decline in physical performance were identified, since the amount of high-intensity running and the relative workload levels decreased in the second half. Positional differences were observed, with wing players covering a greater total distance than backcourt players, performing more high-intensity running and demonstrating a better intermittent recovery capacity (Yo-Yo test outcome) compared to both backcourt players and pivots
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| 18. |
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| 19. |
- Michalsik, L. B., et al.
(författare)
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Technical activity profile and influence of body anthropometry on playing performance in female elite team handball
- 2015
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Ingår i: Journal of Strength and Conditioning Research. - 1064-8011. ; 29:4, s. 1126-1138
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Tidskriftsartikel (refereegranskat)abstract
- Michalsik, LB, Aagaard, P, and Madsen, K. Technical activity profile and influence of body anthropometry on playing performance in female elite team handball. J Strength Cond Res 29(4): 1126-1138, 2015-To determine the physical demands placed on female elite team handball (TH) players in relation to playing position and body anthropometry, female elite TH primarily field players were monitored during match-play using video recording and subsequent computerized technical match analysis during 5 regular tournament match seasons. Technical match activities were distributed in 6 major types of playing actions (shots, breakthroughs, fast breaks, technical errors, defensive errors, and tackles) and further divided into various subcategories (e. g., type of shot, hard or light tackles, claspings, screenings, and blockings). Furthermore, anthropometric measurements were performed. Each player had 28.3 +/- 11.0 (group means +/- SD) high-intense playing actions per match with a total effective playing time of 50.70 +/- 5.83 minutes. On average, each player made 2.8 +/- 2.6 fast breaks, gave 7.9 +/- 14.4 screenings, received 14.6 +/- 9.2 tackles in total, and performed 7.7 +/- 3.7 shots while in offense, along with 3.5 +/- 3.8 blockings, 1.9 +/- 2.7 claspings, and 6.2 6 3.8 hard tackles in defense. Mean body height, body mass, and age in the Danish Premier Female Team Handball League were 175.4 +/- 6.1 cm, 69.5 +/- 6.5 kg, and 25.4 +/- 3.7 years, respectively. Wing players were lighter (63.5 +/- 4.8 kg, p < 0.001) and smaller (169.3 +/- 4.9 cm, p < 0.001) than backcourt players (BP) (70.6 +/- 5.3 kg, 177.0 +/- 5.4 cm) and pivots (PV) (72.5 +/- 4.9 kg, 177.7 +/- 4.9 cm). In conclusion, the present match observations revealed that female elite TH players during competitive games intermittently perform a high number of shortterm, high-intense technical playing actions making modern female elite TH a physically demanding team sport. No sign of technical fatigue were observed, since the amount of intense technical playing actions remained unchanged in the second half. Marked positional differences in the physical demands were demonstrated, with wing players performing more fast breaks and less physical confrontations than BP and PV. Body anthropometry differed substantially between different playing positions. Consequently, this should lead to an increase in physical training in modern female elite TH directed at specific positions and individual physical capacity.
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| 20. |
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| 21. |
- Olsen, Steen, et al.
(författare)
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Creatine supplementation augments the increase in satellite cell and myonuclei number in human skeletal muscle induced by strength training
- 2006
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 573:Pt 2, s. 525-534
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigated the influence of creatine and protein supplementation on satellite cell frequency and number of myonuclei in human skeletal muscle during 16 weeks of heavy-resistance training. In a double-blinded design 32 healthy, male subjects (19-26 years) were assigned to strength training (STR) while receiving a timed intake of creatine (STR-CRE) (n=9), protein (STR-PRO) (n=8) or placebo (STR-CON) (n=8), or serving as a non-training control group (CON) (n=7). Supplementation was given daily (STR-CRE: 6-24 g creatine monohydrate, STR-PRO: 20 g protein, STR-CON: placebo). Furthermore, timed protein/placebo intake were administered at all training sessions. Muscle biopsies were obtained at week 0, 4, 8 (week 8 not CON) and 16 of resistance training (3 days per week). Satellite cells were identified by immunohistochemistry. Muscle mean fibre (MFA) area was determined after histochemical analysis. All training regimes were found to increase the proportion of satellite cells, but significantly greater enhancements were observed with creatine supplementation at week 4 (compared to STR-CON) and at week 8 (compared to STR-PRO and STR-CON) (P<0.01-0.05). At week 16, satellite cell number was no longer elevated in STR-CRE, while it remained elevated in STR-PRO and STR-CON. Furthermore, creatine supplementation resulted in an increased number of myonuclei per fibre and increases of 14-17% in MFA at week 4, 8 and 16 (P<0.01). In contrast, STR-PRO showed increase in MFA only in the later (16 week, +8%) and STR-CON only in the early (week 4, +14%) phases of training, respectively (P<0.05). In STR-CRE a positive relationship was found between the percentage increases in MFA and myonuclei from baseline to week 16, respectively (r=0.67, P<0.05). No changes were observed in the control group (CON). In conclusion, the present study demonstrates for the first time that creatine supplementation in combination with strength training amplifies the training-induced increase in satellite cell number and myonuclei concentration in human skeletal muscle fibres, thereby allowing an enhanced muscle fibre growth in response to strength training.
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| 22. |
- Scheers Andersson, Elina, et al.
(författare)
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No association of maternal gestational weight gain with offspring blood pressure and hypertension at age 18 years in male sibling-pairs : a prospective register-based cohort study
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Maternal gestational weight gain (GWG) is associated with birth weight, obesity, and possibly blood pressure (BP) and hypertension in the offspring. These associations may however be confounded by genetic and/or shared environmental factors. In contrast to previous studies based on non-siblings and self-reported data, we investigated whether GWG is associated with offspring BP and hypertension, in a register-based cohort of full brothers while controlling for fixed shared effects.METHODS: By using Swedish nation-wide record-linkage data, we identified women with at least two male children (full brothers) born 1982-1989. Their BP was obtained from the mandatory military conscription induction tests. We adopted linear and Poisson regression models with robust variance, using generalized estimating equations to analyze associations between GWG and BP, as well as with hypertension, within and between offspring sibling-pairs.RESULTS: Complete data on the mothers' GWG and offspring BP was obtained for 9,816 brothers (4,908 brother-pairs). Adjusted regression models showed no significant associations between GWG and SBP (β = 0.03 mmHg per 1-kg GWG difference, [95% CI -0.08, 0.14], or DBP (β = -0.03 mmHg per 1-kg GWG difference [95% CI -0.11, 0.05]), or between GWG and offspring's risk of hypertension (relative risk = 1.0 [95% CI 0.99, 1.02], neither within nor between siblings.CONCLUSIONS: In this large sibling-pair study, we did not find any significant association between GWG and offspring BP or the risk of hypertension at 18y, when taking genetic and environmental factors shared within sibling pairs into account. Further large sibling studies are required to confirm a null association between GWG and other cardiovascular risk factors.
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| 23. |
- Sparrelid, Ernesto, et al.
(författare)
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How should liver hypertrophy be stimulated? A comparison of upfront associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) and portal vein embolization (PVE) with rescue possibility
- 2021
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Ingår i: Hepatobiliary surgery and nutrition. - : AME Publishing Company. - 2304-3881 .- 2304-389X. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The role of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) in comparison to portal vein embolization (PVE) is debated. The aim of this study was to compare successful resection rates (RR) with upfront ALPPS vs. PVE with rescue ALPPS on demand and to compare the hypertrophy of the liver between ALPPS and PVE plus subsequent rescue ALPPS. Methods: A retrospective analysis of all patients treated with PVE for colorectal liver metastasis (CRLM) or ALPPS (any diagnosis, rescue ALPPS included) at five Scandinavian university hospitals during the years 2013-2016 was conducted. A Chi-square test and a Mann-Whitney U test were used to assess the difference between the groups. A successful RR was defined as liver resection without a 90-day mortality. Results: A total of 189 patients were included. Successful RR was in 84.5% of the patients with ALPPS upfront and in 73.3% of the patients with PVE and rescue ALPPS on demand (P=0.080). The hypertrophy of the future liver remnants (FLRs) with ALPPS upfront was 71% (48-97%) compared to 96% (82-113%) after PVE and rescue ALPPS (P=0.010). Conclusions: Upfront ALPPS offers a somewhat higher successful RR than PVE with rescue ALPPS on demand. The sequential combination of PVE and ALPPS leads to a higher overall degree of hypertrophy than upfront ALPPS.
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