Jaak Jürimäe

University of Tartu, Dorpat, Tartu, Estonia

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Publications (167)241.97 Total impact

  • J. Jürimäe · A.P. Hills · T. Jürimäe

    No preview · Article · Jan 2010
  • Jaak Jürimäe · Jarek Mäestu · Toivo Jürimäe
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    ABSTRACT: The rapid increase in skeletal mass that occurs during puberty is caused by increases in longitudinal growth as well as cortical thickness. The measurement of growth changes during puberty using two-dimensional (dual-energy X-ray absorptiometry) and/or three-dimensional (computed tomography, magnetic resonance imaging) measurement devices provides only a static representation of bone tissue parameters. The measurement of bone turnover markers provides a more dynamic picture of the nature of bone tissue that can be repeated at much shorter intervals during puberty. The bone turnover markers are products of osteoblasts and osteoclasts which can be measured in urine or blood. The increase in different markers of bone turnover coincides with the pubertal growth spurt and thereafter markers decline until they converge into adult values. The initiation of puberty is accompanied by increases in androgens and estrogens. The effects of sex hormones on bone mineral accrual are mediated mainly by growth hormone and insulin-like growth factor-1, but they also exert a direct effect on bone metabolism. Important determinants of bone mineral accrual during puberty include optimal nutritional status, body composition parameters and physical activity pattern. All of these determinants are related to the state of energy balance, while peripheral indicators of energy balance, such as different growth factors and adipocytokines, may also have a positive influence of the growing skeleton. Taken together, bone mineral accrual during puberty is a complex interaction between physical activity pattern, various body composition parameters, specific growth factors and adipocytokines, and also sex hormones.
    No preview · Article · Jan 2010 · Medicine and sport science
  • R Gruodyté · J Jürimäe · M Saar · M Maasalu · T Jürimäe
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    ABSTRACT: The aim of this study was to investigate the relationship between jumping height and bone mineral density (BMD) at femoral neck and lumbar spine in pubertal girls with different physical activity pattern. The participants were 202 adolescent girls aged 13-15 years comprising six groups: controls (N.=43); sport games (N.=56); track sprint (N.=25); rhythmic gymnastics (N.=29); swimming (N.=32); and cross-country skiing (N.=17). Body height, sitting height, and body mass were measured. Predicted age at peak height velocity (APHV), biological maturity age (years from APHV), and pubertal status by Tanner (1962) of the participants was estimated. Femoral neck and lumbar spine (L2-L4) BMD was measured by DXA. The height of vertical jumps, i.e., countermovement jump (CMJ), and rebound jumps for 15 (RJ15s) and 30 (RJ30s) seconds was obtained. RJ15s and RJ30s tests characterized best BMD at lumbar spine and femoral neck in high-impact (i.e., gymnasts and sport games) groups. Vertical jump tests had no significant correlation with measured areal BMD values in physically inactive controls, low-impact (i.e., swimmers and cross-country skiers) and moderate-impact (i.e., sprinters) groups. BMD at femoral neck appears to be more sensitive to the mechanical loading compared to the BMD at lumbar spine. Repeated jumps tests (RJ15s and RJ30s) characterize bone development better than single maximal jump (CMJ) test in pubertal girls.
    No preview · Article · Dec 2009 · The Journal of sports medicine and physical fitness
  • Rita Gruodyte · Jaak Jürimäe · Meeli Saar · Toivo Jürimäe
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    ABSTRACT: The aim of this study was to determine the relationships of bone mineral density (BMD) and content (BMC) with insulin-like growth factor-1 (IGF-1), IGF-binding protein-3 (IGFBP-3) and estradiol in pubertal female athletes. The participants were 170 healthy adolescent girls (13-15 years) who participated in competitive extramural athletic programs, i.e., sports games (n = 49), track sprinting (n = 24), rhythmic gymnastics (n = 23), swimming (n = 24) and cross-country skiing (n = 17). The control group (n = 33) consisted of girls who took part only in compulsory physical education classes at school. The whole-body BMD and femoral neck and lumbar spine BMD and BMC were measured using DXA, and the volumetric BMD was calculated. Venous blood samples to determine the concentration of IGF-1, IGFBP-3 and estradiol were drawn after an overnight fasting. After adjusting for age, body height and body mass, the relationships among BMD variables, IGF-1 and the IGF-1/IGFBP-3 molar ratio remained significant only in the rhythmic gymnast group. BMDs at the femoral neck and lumbar spine were also related to estradiol levels (r = 0.45-0.60; p < 0.05) only in the rhythmic gymnast group. No relationships were found among the measured BMD, IGF axis and estradiol in other athletic groups. Only BMC at the femoral neck remained associated with the IGF-1/IGFBP-3 molar ratio in the rhythmic gymnast group after adjusting for age, body height and body mass. Stepwise multiple regression analysis indicated that IGF-1 and estradiol together explained 42.6% (R(2) x 100) of total variance in the femoral neck BMD and IGF-1 alone 35.4% (R(2) x 100) of the total variance in the femoral neck BMC only in the rhythmic gymnast group. We conclude that femoral neck and lumbar spine BMD correlated with IGF-1, IGF-1/IGFBP-3 molar ratio and estradiol in rhythmic gymnasts. No relationships were found between bone parameters and the hormones used in other athletic groups.
    No preview · Article · Oct 2009 · Journal of Bone and Mineral Metabolism
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    ABSTRACT: The aim of this investigation was to compare the physiological responses of 2000 m rowing ergometer test with 7-min bench pull and leg press tests. We hypothesised that leg press exercise contributes to 2000 m rowing ergometer test results, rather than bench pull performed by arms. College level rowers (n=12) performed 2000 m rowing test and after one day 7-min bench pull and leg press (50% from the 1 RM). Stroke rate, heart rate (HR), blood lactate (LA) and ratings of perceived exertion (RPE) were measured during all tests. The number of repetitions was highest during 2000 m rowing test (194.2+/-19.5) and lowest during bench pull (122.6+/-17.7) (during leg press 173.5+/-11.8). Differences between 2000 m rowing test, leg press and bench pull tests were significant in mean and maximal HR. In LA concentration, the highest values were at 3rd min of recovery after rowing test (14.8+/-1.7 mmol l(-1)). Between bench pull (8.8+/-1.9 and 8.5+/-2.7 mmol l(-1)) and leg press (11.8+/-2.5 and 11.2+/-2.3 mmol l(-1)) tests, the difference in LA concentration was not significant (p>0.05). Ratings of perceived exertion were highest in 2000 m rowing test (19.3+/-0.9), difference with leg press and bench pull tests was not significant. There were significant relationships in mean and maximal HR (r=0.713-0.767) and Borg scale (r=0.764) during rowing test and leg press. The number of repetitions during leg press exercise correlated significantly with rowing test time (r=-0.677). In conclusion, this study suggests that in rowers there are major differences in the physiological adaptation to upper body and leg exercise, performed at similar intensities. Leg press exercise could be used to measure sport-specific strength endurance in rowers.
    No preview · Article · Oct 2009 · Journal of Science and Medicine in Sport
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    ABSTRACT: DXA is an accepted reference method to estimate body composition. However several difficulties in the applicability exist. The equipment is rather expensive, not portable, impractical for measurement of big study populations and it pro-vides a minimal amount of ionizing radiation exposure. The optical device Lipometer (EU Pat.No. 0516251) provides non-invasive, quick, precise and safe measurements of subcutaneous adipose tissue (SAT) layer thicknesses at any site of the human body. Compared to DXA there are some advantages in the Lipometer approach, because this device is portable, quick, not expensive and no radiation is involved. To use these advantages in the field of total body fat% (TBF%) assess-ment, an acceptable estimation of DXA TBF% by Lipometer SAT thicknesses is necessary, which was the aim of this study. Height, weight, waist and hip circumferences, DXA TBF% and Lipometer SAT thicknesses at fifteen defined body sites were measured in 28 healthy men (age: 33.9 ± 16.6 years) and 52 healthy women (age: 40.1 ± 10.7 years). To estimate Lipometer TBF% stepwise multiple regression analysis was applied, using DXA TBF% as dependent variable. Using the fifteen Lipometer SAT thicknesses together with age, height, weight and BMI as independent variables provided the best estimations of Lipometer TBF% for both genders with strong correlations to DXA TBF% (R=0.985 for males and R=0.953 for females). The limits of agreement were –2.48% to +2.48% for males and –4.28% to +4.28% for females. For both genders we received a bias of 0.00%. The results of this paper extend the abilities of the Lipometer by a precise esti-mation of TBF% using DXA as »golden standard«.
    Full-text · Article · Jul 2009 · Collegium antropologicum
  • Jaak Jürimäe · Tatjana Kums · Toivo Jürimäe
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    ABSTRACT: This study aimed to evaluate whether circulating ghrelin is associated with changes in different body composition parameters over a 12-month prospective study period in healthy older females. On 41 postmenopausal women (mean age: 71.0 +/- 6.5 years), ghrelin, leptin, insulin resistance (IR), and body composition parameters were assessed before and after the study period. Trunk fat: leg fat ratio (+3.6%), fat free mass (FFM) (-4.1%), glucose (+5.8%), and IR (+7.0%) were significantly changed (P < 0.05), whereas no changes in height, body mass, body mass index, fat mass (FM), %FM, trunk fat, leptin, ghrelin, and insulin were observed as a result of study period. At baseline, ghrelin correlated negatively (r > -0.306; P < 0.05) with body mass, FM, %FM, trunk fat, FFM, leptin, insulin, and IR. Multivariate linear regression analysis demonstrated that baseline ghrelin concentration was significantly associated only with the mean change in FFM value over the 12-month study period. In conclusion, basal ghrelin concentration predicted the loss of FFM in healthy elderly females. In addition, these results suggest that circulating ghrelin concentration could be regarded as a signal of decreased FFM in healthy elderly females.
    No preview · Article · May 2009 · American Journal of Human Biology
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    ABSTRACT: Adiponectin has been reported to regulate systemic insulin sensitivity as a part of a broader control mechanism in energy balance. However, it is not clear whether adiponectin exerts its positive effects on insulin sensitivity equally in a wide range of obesity. We investigated the association of plasma adiponectin concentration with insulin resistance (IR) in a cross-sectional sample of 98 middle-aged premenopausal women with a wide range of obesity. In addition, we studied the relationship between adiponectin, body composition, and blood biochemical and cardiorespiratory fitness variables. Body composition and fat distribution were measured via dual-energy x-ray absorptiometry in normal-weight (NW) (n = 41, body mass index [BMI] < 25 kg/m(2)) and overweight (OW) (n = 57, BMI > or = 25 kg/m(2)) women. Fasting blood samples were obtained; adiponectin, leptin, insulin, glucose, and insulin-like growth factor-I were measured; and IR index was calculated. The IR index from fasting plasma insulin and plasma glucose levels was estimated using the homeostasis model assessment (HOMA), as follows: fasting plasma insulin (in microliter units per milliliter) x fasting plasma glucose (in millimoles per liter)/22.5. Adiponectin was significantly higher (P = .0001) in NW (14.7 +/- 4.7 microg/mL) compared with OW (9.9 +/- 3.1 microg/mL) women. Significant differences (P < .003) in body mass, BMI, percentage of fat mass, fat mass, trunk fat, trunk fat-leg fat ratio, leptin, insulin, and HOMA were also observed between NW and OW groups. Leptin was independently related to plasma adiponectin (beta = -.259, P = .001) in the overall study group. Plasma adiponectin was only related to trunk fat-leg fat ratio (beta = -.242, P = .002) among NW subjects, whereas plasma adiponectin was related to fat-free mass (beta = .182, P = .0001) and HOMA (beta = -.576, P = .002) among OW women. The inverse relationship between adiponectin and leptin concentrations suggests that leptin may be involved in the regulation of adiponectin in middle-aged premenopausal women. Our data also demonstrate that adiponectin may play an important role in sustaining insulin sensitivity only in OW middle-aged premenopausal women.
    Full-text · Article · May 2009 · Metabolism: clinical and experimental
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    ABSTRACT: The purpose of this cross-sectional study was to determine the physiological reaction to the different intensity Nordic Walking exercise in young females with different aerobic capacity values. Twenty-eight 19-24-year-old female university students participated in the study. Their peak O2 consumption (VO2 peak kg(-1)) and individual ventilatory threshold (IVT) were measured using a continuous incremental protocol until volitional exhaustion on treadmill. The subjects were analysed as a whole group (n = 28) and were also divided into three groups based on the measured VO2 peak kg(-1) (Difference between groups is 1 SD) as follows: 1. >46 ml min(-1) kg(-1) (n = 8), 2. 41-46 ml min(-1) kg(-1) (n = 12) and 3. <41 ml min(-1) kg(-1) (n = 8). The second test consisted of four times 1 km Nordic Walking with increasing speed on the 200 m indoor track, performed as a continuous study (Step 1 - slow walking, Step 2 - usual speed walking, Step 3 - faster speed walking and Step 4 - maximal speed walking). During the walking test expired gas was sampled breath-by-breath and heart rate (HR) was recorded continuously. Ratings of perceived exertion (RPE) were asked using the Borg RPE scale separately for every 1 km of the walking test. No significant differences emerged between groups in HR of IVT (172.4 +/- 10.3-176.4 +/- 4.9 beats min(-1)) or maximal HR (190.1 +/- 7.3-191.6 +/- 7.8 beats min(-1)) during the treadmill test. During maximal speed walking the speed (7.4 +/- 0.4-7.5 +/- 0.6 km h(-1)) and O2 consumption (30.4 +/- 3.9-34.0 +/- 4.5 ml min(-1) kg(-1)) were relatively similar between groups (P > 0.05). However, during maximal speed walking, the O2 consumption in the second and third groups was similar with the IVT (94.9 +/- 17.5% and 99.4 +/- 15.5%, respectively) but in the first group it was only 75.5 +/- 8.0% from IVT. Mean HR during the maximal speed walking was in the first group 151.6 +/- 12.5 beats min(-1), in the second (169.7 +/- 10.3 beats min(-1)) and the third (173.1 +/- 15.8 beats min(-1)) groups it was comparable with the calculated IVT level. The Borg RPE was very low in every group (11.9 +/- 2.0-14.4 +/- 2.3) and the relationship with VO2and HR was not significant during maximal speed Nordic Walking. In summary, the present study indicated that walking is an acceptable exercise for young females independent of their initial VO2 peak level. However, females with low initial VO2 peak can be recommended to exercise with the subjective 'faster speed walking'. In contrast, females with high initial VO2 peak should exercise with maximal speed.
    Full-text · Article · May 2009 · Clinical Physiology and Functional Imaging
  • Article: Rowing
    J. Jürimäe · T. Jürimäe · J. Maestu
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    ABSTRACT: IntroductionPhysical requirementsGrowth and development of successful rowersConclusions ReferencesRecommended reading
    No preview · Article · Apr 2009
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    ABSTRACT: The aim of the study was to examine the development of specific physical, physiological, and biomechanical parameters in 29 young male swimmers for whom measurements were made three times for two consecutive years. During the 400-m front-crawl swimming, the energy cost of swimming, and stroking parameters were assessed. Peak oxygen consumption (VO2 peak) was assessed by means of the backward-extrapolation technique recording VO2 during the first 20 sec. of recovery period after a maximal trial of 400-m distance. Swimming performance at different points of physical maturity was mainly related to the increases in body height and arm-span values from physical parameters, improvement in sport-specific VO2 peak value from physiological characteristics, and improvement in stroke indices on biomechanical parameters. In addition, biomechanical factors characterised best the 400-m swimming performance followed by physical and physiological factors during the 2-yr. study period for the young male swimmers.
    No preview · Article · Mar 2009 · Perceptual and Motor Skills
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    ABSTRACT: To examine the relationship of the markers of bone formation (procollagen type I N-terminal propeptide [PINP]) and bone resorption (type I carboxyterminal telopeptide [ICTP]) with bone mineral content (BMC), bone mineral density (BMD), ghrelin and testosterone in boys during puberty. Sixty boys were divided in three groups (20 boys in each) based on the pubertal stage (G1, I; G2-G3, II; G4-G5, III). Fasting PINP, ICTP, ghrelin and testosterone were measured. Total body BMD, lumbar BMD, lumbar apparent volumetric BMD (BMAD) and BMC were measured by DXA. PINP and ICTP values peaked at the beginning of puberty (Group II). Ghrelin was lower in Groups II and III compared to less mature boys. PINP and ICTP correlated with each other and were associated with lumbar BMAD in total group of boys. Relationships of PINP and ICTP with total BMD, total BMC and lumbar spine BMD in Group I were observed. PINP and ICTP were also correlated with testosterone in Group II and with lumbar spine BMAD in Group III. These data suggest that testosterone stimulates PINP and ICTP in early puberty, while ghrelin has no direct influence on bone turnover markers in boys at different stages of puberty.
    No preview · Article · Mar 2009 · Acta Paediatrica
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    ABSTRACT: The present study analyzed the development of physiological, biomechanical and anthropometrical parameters in young female swimmers and assessed the effect of these parameters on swimming performance during biological maturation. In total, 26 female swimmers participated in the study in which data were annually collected for two consecutive years. Body composition, basic anthropometrical parameters and biological age were measured. During the 400-m front-crawl swimming, the energy cost of swimming and stroking parameters were assessed. Peak oxygen consumption (VO2(peak)) was assessed by means of the backward-extrapolation technique recording VO2 during the first 20 sec of the recovery period after a maximal trial of 400-m distance. During the 2-year follow-up study period, age, height, body mass, body fat %, fat free mass, bone mineral mass, total bone mineral density, arm span and biological maturation values significantly increased during each year (p < 0.05). The tracking of the physical characteristics measured over the 2-year study period was relatively high (r > 0.694), except for the body fat% (r > 0.554). The tracking of the Tanner stages was also high (r = 0.759-0.780). Stepwise regression analyses showed that biomechanical factors (R2 > 0.322; p < 0.05) best characterized the 400-metre swimming performance in young female swimmers, followed by bioenergetical (R2 > 0.311; p < 0.05) and physical (R2 > 0.203; p < 0.05) factors during all three measurement times.
    Full-text · Article · Mar 2009 · Collegium antropologicum
  • J Jürimäe · E Lätt · K Haljaste · P Purge · A Cicchella · T Jürimäe
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    ABSTRACT: The aim of our study was to examine the influence of elevated energy expenditure on ghrelin and BMD in young male competitive swimmers advancing from prepubertal to pubertal maturation levels. The study included 19 healthy swimmers (pubertal stage 1) aged between 10 and 12 years. The participants were at the pubertal stages 2 and 3, and 3 and 4 at the second and third year, respectively. Ghrelin was decreased only after the first year. No changes were observed in leptin during the study period. Testosterone increased according to the pubertal development at each measurements. IGF-I was increased at the third measurement compared to the first two measurements. Total and lumbar spine BMDs increased according to the pubertal development in all boys at each measurements, while no changes in femoral neck BMD were observed. Ghrelin was not related to BMD after adjusting for pubertal status. We conclude that ghrelin was decreased at onset of puberty, while no further changes in ghrelin were seen with advancing pubertal stage. Total and lumbar spine BMD increased, while no changes in femoral neck BMD occurred. Ghrelin did not appear to have a direct influence on BMD in young male competitive swimmers.
    No preview · Article · Mar 2009 · International Journal of Sports Medicine
  • Jaak Jürimäe · Tatjana Kums · Toivo Jürimäe
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    ABSTRACT: We investigated the relationship between the decrease in bone mineral mass (BMC) and bone mineral density (BMD) values with baseline adipocytokine and ghrelin concentrations in physically active postmenopausal women. Leptin, adiponectin, ghrelin, BMC, BMD and different body composition values were measured in 35 women (age: 69.7+/-6.0 years) before and after a 12-month prospective study period. Significant (P<0.05) decreases in fat-free mass (FFM) (by 2.56%) and BMC (by 1.63%) and increases in adiponectin (by 14.8%) were seen in older females as a result of the study period. The independent variables that were associated with decreases in total BMC were baseline fat mass (FM) and adiponectin explaining 30.6% (R(2)x100) of the total variance. In another model, baseline FFM and leptin were the independent variables that explained 20.6% (P<0.05) of the total variance in the decreases in total BMD value. The variables that were associated with decreases in femoral neck BMD were FM and leptin (R(2)=0.102; P<0.05), while the independent variables were baseline trunk fat:leg fat ratio and adiponectin in the model with decreases in lumbar spine BMD as the dependent variable, and accounted for 13.1% (P<0.05) of the decreases in BMD variance. Initial adiponectin concentration together with specific body composition characteristics predicted loss in BMC and lumbar spine BMD values, while initial leptin concentration together with specific body composition parameters determined the loss in total and femoral neck BMD values in physically active older women.
    No preview · Article · Mar 2009 · European Journal of Endocrinology
  • Toivo Jürimäe · Jaak Jürimäe · Jarek Mäestu

    No preview · Article · Mar 2009 · Medicina Sportiva
  • Raul Rämson · Jaak Jürimäe · Toivo Jürimäe · Jarek Mäestu
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    ABSTRACT: The aim of this study was to investigate changes in the stress hormones testosterone and cortisol after a task-specific exercise during a high-volume endurance training cycle in men rowers. Eight highly trained men rowers were investigated during a high-volume, low-intensity training period. A 2-hour, low-intensity, long-distance rowing (LDT) test was conducted at baseline, after a high-volume period, and after the recovery period. Training and performance intensities were obtained at the graded incremental test, were preset individually, and were the same during all LDTs. Fasting blood samples were taken during the same days as the LDTs. Exercise-induced blood samples were taken before, 5 minutes after, and 30 minutes after (post 30') the completion of each LDT. There were no significant changes in fasting cortisol and testosterone values during the whole study period, and there were no significant changes in cortisol and testosterone concentrations during the LDT. However, testosterone concentration was significantly decreased at post 30' compared with posttest values during the second LDT that was held after the 2-week high-training-volume period, and, during the second LDT, post 30' values of cortisol tended to be decreased compared with posttest values (p = 0.063). In conclusion, changes in the concentrations of testosterone and cortisol after long-distance rowing indicate decreased adaptivity after the training-specific performance test.
    No preview · Article · Mar 2009 · The Journal of Strength and Conditioning Research
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    ABSTRACT: The aim of the present study was to assess the influence of regular physical activity on plasma ghrelin concentration in pre-pubertal and pubertal boys. In addition, the impact of ghrelin concentration on bone mineral density (BMD) was examined. In total, 56 healthy schoolboys aged between 10 and 16 yr were divided into the swimming (no.=28) and the control (no.=28) groups. The subjects were matched by age and body mass index (BMI), generating 9 matched pairs in pubertal group I (Tanner stage 1), 11 pairs in group II (Tanner stages 2 and 3), and 8 pairs in group III (Tanner stages 4 and 5). Swimmers in pubertal groups II and III had significantly (both p<0.05) higher mean ghrelin levels than the controls (group II: 1126.8+/-406.0 vs 868.3+/-411.2 pg/ml; group III: 1105.5+/-337.5 vs 850.8+/-306.0 pg/ml, respectively), whereas no difference was seen in the pubertal group I (1230.8+/-386.0 vs 1272.7+/-424.4 pg/ml). Ghrelin was the most important hormonal determinant for total BMD and lumbar apparent volumetric BMD (BMAD) (R2=27.2% and R2=19.8%, respectively) in swimmers, whereas in control boys, plasma IGF-I was the most important hormonal predictor accounting for 41.8% of the variability of total BMD and 20.4% of the variability of lumbar BMAD. In conclusion, ghrelin concentration decreased during puberty in physically inactive boys, while in regularly physically active boys it remained relatively unchanged. Ghrelin appears to be an important hormonal predictor for BMD in physically active boys, while BMD is mostly determined by IGF-I in physically inactive boys.
    No preview · Article · Jan 2009 · Journal of endocrinological investigation
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    ABSTRACT: Purpose: The aim of this investigation was to measure plasma visfatin and ghrelin responses to a single endurance rowing training session in male competitive single scull rowers. Methods: Nine national level male rowers (20.1 ± 1.5 yr; 183.9 ± 4.3 cm; 81.0 ± 5.0 kg; 10.8 ± 3.3% body fat) completed two trials (exercise or control) on separate days. The exercise consisted of a prolonged rowing training session lasting ∼2 h (distance = 20.7 ± 1.4 km; HR = 133 ± 4 bpm; intensity = 80.2 ± 1.6% of the HR turn point) followed by a 30-min rest. Venous blood samples were collected before and after on-water rowing. The control trial consisted of rest and blood collection similar to exercise trial. Results: No differences were found at baseline values for plasma visfatin, ghrelin, and leptin for both trials. The estimated energy expenditure of the exercise trial was 1200-1500 kcal. Plasma visfatin (-10.0%; P < 0.05) and leptin (-20.0%; P < 0.05) were reduced, and ghrelin concentration was increased (+12.2%; P < 0.05) after a 30-min postexercise. No differences in plasma visfatin, ghrelin, or leptin over time were observed during control trial. There was no relationship between basal visfatin and body composition, energy balance, aerobic power, or blood biochemical data. Plasma visfatin (r = -0.76) and ghrelin (r = 0.75) measured immediately after the training session were related (P < 0.05) to the distance covered, and no relation was observed for postexercise leptin (r = -0.16; P > 0.05). Conclusion: Acute negative energy balance induced by a single endurance rowing training session elicited an inverse metabolic response in visfatin and ghrelin in competitive male rowers. Our results suggest that peripheral markers of negative energy balance, such as visfatin and ghrelin, may be regarded as signals for metabolic reaction to the energy cost of acute exercise. The results of our study also suggest that an energy-deficit threshold must be met for the response to occur.
    No preview · Article · Dec 2008 · Medicine & Science in Sports & Exercise
  • T Jürimäe · T Hurbo · J Jürimäe
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    ABSTRACT: The purpose of the present study was to examine the relationship of handgrip strength with basic anthropometric variables, hand anthropometric variables, total body and hand composition, total body and hand bone mineral density (BMD) and bone mineral content (BMC) in prepubertal children aged between 8 and 11 years (n=64, 27 boys, 37 girls). Height and body mass were measured and body mass index (BMI kg/m2) was calculated. Biceps and triceps skinfolds, arm relaxed, arm flexed, forearm and wrist girths, acromiale-radiale, radiale-stylion-radiale and midstylion-dactylion length and humerus breadth were measured. Specific hand anthropometric variables according to Visnapuu and Jürimäe [2007. Handgrip strength and hand dimensions in young handball and basketball players. J. Strength Cond. Res. 21, 923-929] were used. Five fingers' spans, fingers' lengths and perimeters of the hand were measured. Total body and right-hand fat percentage, fat mass and lean mass (LBM) were measured by dual-energy X-ray absorptiometry (DXA). Right-hand BMC and BMD were analysed from the bone variables. Maximal handgrip strength of the right hand was measured with the hand dynamometer. Stepwise multiple regression analysis indicated that the most important predictive value from the basic anthropometric variables was body height, explaining 76.1% (R2 x 100), 40.7% and 50.6% of the handgrip strength in boys, girls and total group, respectively. Measured skinfold thicknesses and breadths were not related to handgrip strength in any group. Forearm girths significantly predicted handgrip strength in boys (30.8%), girls (43.4%) and total group (43.4%). As a rule, handgrip strength was more dependent on the anthropometric and body composition variables in boys than girls. It was concluded that body height, forearm girth, midstylion-dactylion and acromiale-radiale length and hand LBM and BMC are the most limiting factors influencing handgrip strength in prepubertal children.
    No preview · Article · Dec 2008 · Homo: internationale Zeitschrift fur die vergleichende Forschung am Menschen