Biomedical subjects

U Wisløff

Publications and source records attributed to U Wisløff.

At least 19 recordsLinked to original sources

PubMed2006

Effect of a short-acting NO donor on bubble formation from a saturation dive in pigs.

It has previously been reported that a nitric oxide (NO) donor reduces bubble formation from an air dive and that blocking NO production increases bubble formation. The present study was initiated to see whether a short-acting NO donor (glycerol trinitrate, 5 mg/ml; Nycomed Pharma) given immediately before start of decompression would affect the amount of vascular bubbles during and after decompression from a saturation dive in pigs. A total of 14 pigs (Sus scrofa domestica of the strain Norsk landsvin) were randomly divided into an experimental (n = 7) and a control group (n = 7). The pigs were anesthetized with ketamine and alpha-chloralose and compressed in a hyperbaric chamber to 500 kPa (40 m of seawater) in 2 min, and they had 3-h bottom time while breathing nitrox (35 kPa O(2)). The pigs were all decompressed to the surface (100 kPa) at a rate of 200 kPa/h. During decompression, the inspired Po(2) of the breathing gas was kept at 100 kPa. Thirty minutes before decompression, the experimental group received a short-acting NO donor intravenously, while the control group were given equal amounts of saline. The average number of bubbles seen during the observation period decreased from 0.2 to 0.02 bubbles/cm(2) (P < 0.0001) in the experimental group compared with the controls. The present study gives further support to the role of NO in preventing vascular bubble formation after decompression.

Animals↗

PubMed2005

Diving-induced venous gas emboli do not increase pulmonary artery pressure.

Venous gas emboli are frequently observed in divers even if proper decompression procedures are followed. This study was initiated to determine if pulmonary artery pressure increases in asymptomatic divers, which could increase the risk of arterial embolization due to passage of venous gas emboli from the right to the left side of the heart. Recordings of venous gas emboli and estimation of pulmonary artery pressure by non-invasive transthoracic echocardiography were applied in 10 recreational scuba diving volunteers before and 20, 40, 60, and 80 min after simulated dives to 18 m (80 min bottom time) in a hyperbaric chamber. The ratio between pulmonary artery acceleration time and right ventricular ejection time was used as an estimate of pulmonary artery pressure. None of investigated divers had signs of decompression sickness. Despite the post-dive presence of the venous gas emboli, measured in the region of the pulmonary valve annulus (mean=1.71 bubbles.cm-2, 40 min after dive), the ratio between pulmonary artery acceleration time and right ventricular ejection time did not decrease, but actually increased (from 0.43+/-0.06 to 0.49+/-0.06, 40 min after dive; p<0.05), suggesting a decrease in pulmonary artery pressure after the dive. We conclude that diving-induced venous gas bubbles do not cause significant changes in the central circulation which could increase the risk of arterial embolization.

Adult↗

PubMed2005

Endurance training and testing with the ball in young elite soccer players.

BACKGROUND: The aerobic capacity of soccer players substantially influences their technical performance and tactical choices. Thus, the assessment of soccer players' aerobic performance should be of interest for soccer coaches in order to evaluate and improve their endurance training sessions. In this study, we present a new test to assess aerobic performance in soccer by means of a specific dribbling track: the Hoff test. We further determined whether improvement in maximal oxygen uptake was reflected in increased distance covered in the Hoff test. METHODS: We tested 18 male soccer players (14 years old) both in the laboratory and using the Hoff test before and after 8 weeks of soccer training. RESULTS: The distance covered in the Hoff test correlated significantly with maximum oxygen uptake, and improved by 9.6% during the 8 week training period, while maximum oxygen uptake and running economy improved by 12 and 10%, respectively. Backward multiple regression showed maximum oxygen uptake to be the main explanatory variable for the distance covered in the Hoff test. CONCLUSION: The present study demonstrated a significant correlation between laboratory testing of VO(2max) and performance in the Hoff test. Furthermore, training induced improvements in VO(2max) were reflected in improved performance in the Hoff test. We suggest that it should be a goal for active U-15 soccer players to cover more than 2100 metres in the Hoff test, as this requires a VO(2max) of above 200 ml/kg(0.75)/min, which should serve as a minimum in modern soccer.

Adolescent↗

PubMed2005

Appropriate interpretation of aerobic capacity: allometric scaling in adult and young soccer players.

OBJECTIVE: To compare aerobic capacity of young and adult elite soccer players using appropriate scaling procedures. METHODS: Twenty four male adult (mean (SD) age 24 (2) years, weight 75.7 (7.2) kg, VO2max 66.6 (5.2) ml/lbm/min, where lbm is lean body mass in kg) and 21 youth (14 (0.4) years, 60.2 (7.3) kg, 66.5 (5.9) ml/lbm/min) elite soccer players took part in the study. Allometric equations were used to determine the relation between maximal and submaximal oxygen cost of running (running economy) and body mass. RESULTS: Maximal and submaximal oxygen uptake increased in proportion to body mass raised to the power of 0.72 (0.04) and 0.60 (0.06) respectively. The VO2max of adult players was similar to that of the youth players when expressed in direct proportion to body mass--that is, ml/kg/min--but 5% higher (p<0.05) when expressed using appropriate procedures for scaling. Conversely, compared with seniors, youth players had 13% higher (p<0.001) energy cost of running--that is, poorer running economy--when expressed as ml/kg/min but not when expressed according to the scaling procedures. CONCLUSIONS: Compared with the youth soccer players, VO2max in the seniors was underestimated and running economy overestimated when expressed traditionally as ml/lbm/min. The study clearly shows the pitfalls in previous studies when aerobic capacity was evaluated in subjects with different body mass. It further shows that the use of scaling procedures can affect the evaluation of, and the resultant training programme to improve, aerobic capacity.

Adolescent↗

PubMed2004

Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players.

BACKGROUND: A high level of strength is inherent in elite soccer play, but the relation between maximal strength and sprint and jumping performance has not been studied thoroughly. OBJECTIVE: To determine whether maximal strength correlates with sprint and vertical jump height in elite male soccer players. METHODS: Seventeen international male soccer players (mean (SD) age 25.8 (2.9) years, height 177.3 (4.1) cm, weight 76.5 (7.6) kg, and maximal oxygen uptake 65.7 (4.3) ml/kg/min) were tested for maximal strength in half squats and sprinting ability (0-30 m and 10 m shuttle run sprint) and vertical jumping height. RESULT: There was a strong correlation between maximal strength in half squats and sprint performance and jumping height. CONCLUSIONS: Maximal strength in half squats determines sprint performance and jumping height in high level soccer players. High squat strength did not imply reduced maximal oxygen consumption. Elite soccer players should focus on maximal strength training, with emphasis on maximal mobilisation of concentric movements, which may improve their sprinting and jumping performance.

Adult↗

PubMed2004

Field and laboratory testing in young elite soccer players.

AIM: To determine if there are correlations between the physical fitness of young soccer players assessed by field and laboratory testing. METHODS: Thirty four male soccer players took part in the study (mean (SD) age 17.5 (1.1) years, height 177.8 (6.7) cm, weight 70.5 (6.4) kg). Maximal oxygen uptake (VO(2)MAX) during treadmill running and vertical jump height on a force platform were measured in the laboratory. Field tests consisted of a soccer specific endurance test (Bangsbo test) and 30 m sprint with 10 m lap times. RESULTS: The Bangsbo test correlated with the lowest velocity associated with VO(2)MAX (vVO(2)MAX; R(2) = 0.55, p<0.001), but not with VO(2)MAX. Sprint times at 30 m and 20 m were related to peak extension velocity and peak extension force measured during vertical jumping, but not to vertical jump height per se. The jumping force and velocity could explain 46% of the 30 m sprint performance (R(2) = 0.46, p<0.001). CONCLUSION: The Bangsbo test and 30 m sprint test correlate with vVO(2)MAX and vertical jump force and velocity respectively. The Bangsbo test does not give a good estimate of VO(2)MAX in young soccer players.

Adolescent↗

PubMed2003

Left ventricular mechanics during exercise: a Doppler and tissue Doppler study.

AIMS: To study left ventricular mechanics of exercise with Doppler and tissue Doppler. METHODS AND RESULTS: Twenty-one males (mean age, 26; height, 184 cm; weight, 84 kg), exercised on a bicycle, with increasing workload, with oxygen uptake, Doppler flow and tissue Doppler recordings during exercise. There was correlation between peak systolic LVOT flow and annulus velocity; R=0.72, (p<0.001) and between peak mitral E flow and annulus E(a) velocity; R=0.68(p<0.001). Finally there was correlation between peak LVOT and mitral flow velocity; R=0.83(p<0.001) and peak systolic and early diastolic annulus velocity R=0.69(p<0.001). All intervals of the heart cycle decreased with RR-interval. There was a linear relation between diastolic filling and RR-interval, while ejection period was less increased with RR-intervals above 600 ms, and thus not a linear relationship. There was no change in E/E(a) ratio during exercise. CONCLUSIONS: Mechanism for increased filling as well as ejection during exercise seems to be increased contraction and relaxation velocity, with no evidence of Frank-Starling mechanism. Bazett's formula gives a better heart rate correction of LVET at high heart rates than Weissler's.

Adult↗

PubMed2003

Soccer specific testing of maximal oxygen uptake.

AIM: Endurance capacity in soccer players is important. A soccer specific test for direct measurement of maximal oxygen uptake does, however, not exist. The aim of this study was to evaluate maximal oxygen uptake in a soccer specific field test, compared to treadmill running. METHODS: Ten male soccer players (age 21.9+/-3.0 years, body mass 73.3+/-9.5 kg, height 179.9+/-4.7 cm) participated in the study, and 5 endurance trained men (age 24.9+/-1.8 years, body mass 81.5+/-3.7 kg, height 185.6+/-3.1 cm) took part in a comparison of the portable and the stationary metabolic test systems. The soccer players accomplished a treadmill test and a soccer specific field test containing dribbling, repetitive jumping, accelerations, decelerations, turning and backwards running. RESULTS: Maximal oxygen uptake was similar in field (5.0+/-0.5 L x min(-1)) and laboratory (5.1+/-0.7 L x min(-1)) tests, as were maximal heart rate, maximal breathing frequency, respiratory exchange ratio and oxygen pulse. Maximal ventilation was 5.4% higher at maximal oxygen uptake during treadmill running. CONCLUSION: These findings show that testing of maximal oxygen uptake during soccer specific testing gives similar results as during treadmill running, and therefore serves as a valid test of maximal oxygen uptake in soccer players.

Adult↗

PubMed2002

Surgical manipulation, but not moderate exercise, is associated with increased cytokine mRNA expression in the rat soleus muscle.

Interleukin (IL)-6 production in contracting skeletal muscle and IL-6 concentration in plasma are increased after prolonged and strenuous exercise. However, as tissue stress or damage are unspecific triggers of increased cytokine levels, we examined whether moderate muscle activity is an independent stimulus for cytokine expression, and to which extent invasive procedures might affect the results. Soleus muscles were isolated from sedentary rats or from rats that had been running on a treadmill at moderate intensity (70% of maximal oxygen uptake) for 1 h. In another group the soleus muscle was prepared in situ and stimulated intermittently at 5 Hz for 1 h, so that maximal developed force declined by 30%. In situ prepared soleus muscles not subjected to electrical stimulation were used as controls. Messenger RNA (mRNA) expression of 11 cytokines was analysed in the soleus muscles using multiprobe RNAse protection assay, and IL-6 plasma concentration was measured by enzyme-linked immunosorbent assay. Treadmill exercise did not affect the mRNA expression of any of the measured cytokines in the soleus muscle. Irrespective of electrical stimulation, mRNA expression of IL-6 and IL-1beta were significantly increased in the surgically manipulated soleus muscles. Interleukin-6 plasma concentration was not affected by treadmill running or electrical stimulation. Conclusion, gentle surgical manipulation is a strong stimulus for IL-6 and IL-1beta mRNA synthesis in skeletal muscle, whereas exercise or electrical muscle stimulation at moderate intensity does not independently affect cytokine mRNA levels in the contracting soleus.

Animals↗

PubMed2002

Cardiomyocyte contractility and calcium handling partially recover after early deterioration during post-infarction failure in rat.

The aim of the study was to determine whether progression of heart failure is associated with deterioration of cardiomyocyte function. Cell dimensions, contractility and calcium transients were measured in cardiomyocytes isolated from the left ventricle of female Wistar rats 1, 4, and 13 weeks after coronary artery ligation or sham-operation. Relative cardiomyocyte shortening decreased from 26% in controls to 11% 1 week after myocardial infarction and recovered to 18 and 20% after 4 and 13 weeks, respectively. Diastolic and systolic calcium concentrations increased markedly 1 week after myocardial infarction with subsequent reduction after 4 and 13 weeks. Time to 50% relaxation was prolonged by 31% after 1 week and 20% after 4 and 13 weeks with corresponding changes in diastolic calcium clearance. Cardiomyocyte length increased by 6, 24, and 26% after 1, 4 and 13 weeks, respectively, whereas myocyte width increased by 4, 11 and 27%. Cardiomyocytes adjacent to the infarct hypertrophied more and initially had more markedly impaired function than in the remote area. Left ventricular diastolic diameter assessed by echocardiography increased by 47, 66 and 84% after 1, 4 and 13 weeks, respectively, and systolic diameter increased by 120, 162 and 194%. Left ventricular end-diastolic pressure increased from 6 mmHg to 24, 25 and 36 mmHg. Whereas initial deterioration of cardiac function is associated with reduced cardiomyocyte contractile function, chronic heart failure progression is not accompanied by further impairment of intrinsic cardiomyocyte contractility in this model. Cardiomyocyte hypertrophy and dysfunction are more marked adjacent to the infarction.

Animals↗

PubMed2002

Soccer specific aerobic endurance training.

BACKGROUND: In professional soccer, a significant amount of training time is used to improve players' aerobic capacity. However, it is not known whether soccer specific training fulfils the criterion of effective endurance training to improve maximal oxygen uptake, namely an exercise intensity of 90-95% of maximal heart rate in periods of three to eight minutes. OBJECTIVE: To determine whether ball dribbling and small group play are appropriate activities for interval training, and whether heart rate in soccer specific training is a valid measure of actual work intensity. METHODS: Six well trained first division soccer players took part in the study. To test whether soccer specific training was effective interval training, players ran in a specially designed dribbling track, as well as participating in small group play (five a side). Laboratory tests were carried out to establish the relation between heart rate and oxygen uptake while running on a treadmill. Corresponding measurements were made on the soccer field using a portable system for measuring oxygen uptake. RESULTS: Exercise intensity during small group play was 91.3% of maximal heart rate or 84.5% of maximal oxygen uptake. Corresponding values using a dribbling track were 93.5% and 91.7%. No higher heart rate was observed during soccer training. CONCLUSIONS: Soccer specific exercise using ball dribbling or small group play may be performed as aerobic interval training. Heart rate monitoring during soccer specific exercise is a valid indicator of actual exercise intensity.

Adult↗

PubMed2001

Aerobic endurance training reduces bubble formation and increases survival in rats exposed to hyperbaric pressure.

1. The formation of bubbles is the basis for injury to divers after decompression, a condition known as decompression illness. In the present study we investigated the effect of endurance training in the rat on decompression-induced bubble formation. 2. A total of 52 adult female Sprague-Dawley rats (300-370 g) were randomly assigned to one of two experimental groups: training or sedentary control. Trained rats exercised on a treadmill for 1.5 h per day for 1 day, or for 2 or 6 weeks (5 days per week) at exercise intervals that alternated between 8 min at 85-90% of maximal oxygen uptake (VO2,max) and 2 min at 50-60% of VO2,max. Rats were compressed (simulated dive) in a decompression chamber in pairs, one sedentary and one trained, at a rate of 200 kPa x min(-1) to a pressure of 700 kPa, and maintained for 45 min breathing air. At the end of the exposure period, rats were decompressed linearly to the 'surface' (100 kPa) at a rate of 50 kPa x min(-1). Immediately after reaching the 'surface' (100 kPa) the animals were anaesthetized and the right ventricle was insonated using Doppler ultrasound. 3. Intensity-controlled interval training significantly increased VO2,max by 12 and 60% after 2 and 6 weeks, respectively. At 6 weeks, left and right ventricular weights were 14 and 17 % higher, respectively, in trained compared to control rats. No effect of training was observed on skeletal muscle weight. Bubble formation was significantly reduced in trained rats after both 2 and 6 weeks. However, the same effect was seen after a single bout of aerobic exercise lasting 1.5 h on the day prior to decompression. All of the rats that exercised for 1.5 h and 2 weeks, and most of those that trained for 6 weeks, survived the protocol, whereas most sedentary rats died within 60 min post-decompression. 4. This study shows that aerobic exercise protects rats from severe decompression and death. This may be a result of less bubbling in the trained animals. The data showed that the increase in aerobic capacity per se was not the main mechanism, but rather an acute effect that was most notable 20 h after a single, or the last, exercise bout, with less effect after 48 h.

Animals↗

PubMed2001

Increased contractility and calcium sensitivity in cardiac myocytes isolated from endurance trained rats.

OBJECTIVE: Regular exercise enhances cardiac function and modulates myocyte growth in healthy individuals. The purpose of the present study was to assess contractile function and expression of selected genes associated with intracellular Ca2+ regulation after intensity controlled aerobic endurance training in the rat. METHODS: Female Sprague-Dawley rats were randomly assigned to sedentary control (SED) or treadmill running (TR) 2 h per day, 5 days per week for 2, 4 or 13 weeks. Rats ran 8-min intervals at 85-90% of VO2max separated by 2 min at 50-60%. Myocyte length, intracellular Ca2+ (Fura-2), and intracellular pH (BCECF) were measured in dissociated cells in response to electrical stimulation at a range of stimulation rates. RESULTS: The increase in VO2max plateaued after 6-8 weeks, 60% above SED. After 13 weeks, left and right ventricular weights were 39 and 36% higher than in SED. Left ventricular myocytes were 13% longer, whereas width remained unchanged. After 4 weeks training, myocyte contractility was approximately 20% higher in TR. Peak systolic intracellular Ca2+ and time for the decay from systole were 20-35 and 12-17% lower, respectively. These results suggest that increased myofilament Ca2+ sensitivity is the dominant effect responsible for enhanced myocyte contractility in TR. Intracellular pH progressively decreased as stimulation frequency was increased in the SED group. This decrease was markedly attenuated in TR and the intracellular pH was significantly higher in the TR group at a stimulation rate of 5-10 Hz. This effect may contribute to the increased contractility observed at the higher stimulation frequencies in TR. A higher intrinsic myofilament Ca2+ sensitivity was observed in permeabilised myocytes from the TR group under conditions of constant pH and [Ca2+]. Western blot analysis indicated 21 and 46% higher myocardial SERCA-2 and phospholamban, but unaltered Na+/Ca(2+)-exchanger levels. Competitive RT-PCR revealed that TR significantly increased Na+/H(+)-exchanger mRNA. CONCLUSION: Intensity controlled interval training increases cardiomyocyte contractility. Higher myofilament Ca(2+)-sensitivity, and enhanced Ca(2+)-handling and pH-regulation are putative mechanisms. Our results suggest that physical exercise induces adaptive hypertrophy in cardiac myocytes with improved contractile function.

Animals↗

PubMed2001

Atrioventricular plane displacement in female endurance athletes.

INTRODUCTION: A novel hypothesis for increased ventricular pumping describes the heart as a displacement pump, in which atrioventricular plane displacement (AVPD) is an important mechanism. The hypothesis predicts that AVPD increases at high heart rates. The aim of the present study was to determine whether AVPD increases during exercise at high heart rates. A secondary aim was to study the left ventricular function and dimensions in endurance-trained young female athletes. METHODS: Eight female cross-country skiers (18.5 +/- 0.9 yr, 169.3 +/- 2.9 cm, 55.7 +/- 4.2 kg, and 64.8 +/- 3.7 mL x kg(-1) x min(-1) in maximal oxygen uptake) were compared with seven sedentary female controls (18.0 +/- 0.6 yr, 175.0 +/- 2.5 cm, 71.1 +/- 4.1 kg, and 42.8 +/- 3.0 mL x kg(-1) x min(-1) in maximal oxygen uptake). Cardiac anatomy and function were assessed by echocardiography. RESULTS: Whereas left ventricular ejection fraction (LVEF) increased in both groups, AVPD fell significantly during exercise. AVPD did not correlate with LVEF, and there were no differences in AVPD between groups either at rest or during exercise. Cardiac output index (mL x lean body mass(-0.67)) and stroke volume index (mL x lean body mass(-1)) were higher in the trained group. The trained group had a larger left ventricular mass, and left ventricular internal dimensions, scaled to lean body mass. CONCLUSIONS: This first study to examine AVPD at rest and during exercise in endurance-trained athletes did not indicate that AVPD is an important mechanism of increased cardiac pumping during exercise. Endurance-trained female athletes have larger left ventricular dimensions and increased function as compared with sedentary subjects.

Adolescent↗

PubMed2001

Intensity-controlled treadmill running in rats: VO(2 max) and cardiac hypertrophy.

Physiological studies of long-term cardiovascular adaptation to exercise require training regimens that give robust conditioning effects and adequate testing procedures to quantify the outcome. We developed a valid and reproducible protocol for measuring maximal oxygen uptake (VO(2 max)), which was reached at a 25 degrees inclination with a respiratory exchange ratio > 1.05 and blood lactate > 6 mmol/l. The effect of intensity-controlled aerobic endurance training was studied in adult female and male rats that ran 2 h/day, 5 days/wk, in intervals of 8 min at 85-90% of VO(2 max) and 2 min at 50-60% of VO(2 max), with adjustment of exercise level according to VO(2 max) every week. After 7 wk, the increase in VO(2 max) plateaued at 60-70% above sedentary controls. Ventricular weights and myocyte length were up 25-30% and 6-12%, respectively. Work economy, oxygen pulse, and heart rate were sufficiently changed to indicate substantial cardiovascular adaptation. The model mimics important human responses to training and could be used in future studies on cellular, molecular, and integrative mechanisms of improved cardiovascular function.

Animals↗

PubMed2001

Regional expression of endothelin-1, ANP, IGF-1, and LV wall stress in the infarcted rat heart.

We hypothesized that myocardial infarction induces regional and temporal differences in endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and insulin-like growth factor-1 (IGF-1) gene expression that correlate with left ventricular (LV) wall stress. Echocardiography and LV pressure measurements were performed in coronary artery-ligated or sham-operated rats. Gene expression was measured by competitive RT-PCR in the infarct, border zone, and remote area and in regionally isolated cardiomyocytes. ET-1 and IGF-1 expression was highest in the infarcted myocardium, whereas ANP expression was highest in noninfarcted myocardium. For all genes, remote area expression was highest after 7 days. At 42 days, ANP maintained maximum expression, ET-1 decreased to 50% of peak levels, and IGF-1 was normalized. Cardiomyocyte expression followed the same pattern as in the myocardium except for a markedly lower IGF-1 expression. Diastolic wall stress was the best hemodynamic variable to predict ET-1 and ANP expression in the remote area. We conclude that ET-1, ANP, and IGF-1 are expressed in different patterns in the infarcted heart in relation to time, functional regions, cellular distribution, and mechanical load.

Animals↗

PubMed1999

Maximal strength training improves work economy in trained female cross-country skiers.

PURPOSE: The present study examines the hypothesis that maximal strength training improves work economy and anaerobic threshold in trained female cross-country skiers while working on a ski ergometer. METHODS: Fifteen female cross-country skiers (17.9 +/- 0.3 yr, 166.7 +/- 1.3 cm, 60.1 +/- 1.9 kg, and 55.3 +/- 1.3 mL x kg(-1) x min(-1)) participated in the study. Eight skiers made up the high-intensity strength-trained group, and seven served as the control group. Endurance performance was tested on a specially instrumented ski ergometer. Strength training and testing simulated double poling in cross-country skiing. RESULTS: A significant (P < 0.001) improvement in double-poling economy on the ski ergometer was observed among the strength-trained group. Anaerobic threshold did not change during the experimental period for either group. After a 9-wk training period, time to exhaustion increased from 5.2 (+/-0.9) to 12.3 (+/-1.6) min (P < 0.001) and from 4.0 (+/-0.9) to 6.3 (+/-0.9) min (P < 0.01) for the strength and control group, respectively. Time to exhaustion was significantly higher (P < 0.001) for the strength group compared with the control group after training. One repetition maximum increased 14.5% (1.8) (P < 0.001) in the strength group but was unchanged in the control group. Expressed in relation to peak force at one repetition maximum, strength training resulted in a significant reduction in the relative available force employed working on the ski ergometer (P < 0.01). Time to peak force at maximal aerobic velocity on the ski ergometer was significantly reduced in the strength-training group (P < 0.01). CONCLUSIONS: It is concluded that maximal strength training in the upper-body improved the double-poling performance by improved work economy. Work economy was improved by a reduction in relative workload and time to peak force while double poling.

Adolescent↗

PubMed1998

Strength and endurance of elite soccer players.

PURPOSE: The major purpose of the present study was to examine whether there exists a relationship between preseasonal physiological tests and performance results in the soccer league. Further, it investigated maximal oxygen uptake and maximal strength in proportion to body mass for soccer players. A secondary aim was to establish some normative data of Norwegian elite soccer players. METHODS: Two teams from the Norwegian elite soccer league participated in the study. RESULTS/CONCLUSION: The present study supports previous investigations indicating a positive relationship between maximal aerobic capacity, physical strength, and performance results in the elite soccer league. It is concluded that for soccer players, maximal oxygen uptake should be expressed in relation to body mass raised to the power of 0.75 and maximal strength in relation to body mass raised to the power of 0.67, when the aim is to evaluate maximal aerobic capacity when running and strength capacity among players with different body mass. Midfield players had significantly higher maximal oxygen uptake compared with defense players using the traditional expression, mL x kg(-1) x min(-1), while no significant differences were found expressing maximal oxygen uptake either absolutely (L x min[-1]) or in relation to body mass raised to the power of 0.75 (mL x kg[-0.75] x min[-1]) among players grouped by position. There was a significant correlation (r = 0.61, P < 0.01) between squat IRM and vertical jump height. Vertical jump heights for defense and forward players were significantly higher compared with midfield players. Mean results from the laboratory test were 63.7 mL x kg(-1) x min(-1) or 188.6 mL x kg[-0.75] x min(-1) for maximal oxygen uptake, 150 kg or 8.0 kg x mb(-0.67) for 90 degrees squats, 79.9 kg or 4.4 kg x mb(-0.67) for bench press. Mean values of vertical jump height were 54.9 cm.

Adult↗