Jaak Jürimäe

University of Tartu, Dorpat, Tartu, Estonia

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Publications (135)217.66 Total impact

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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«.
    Collegium antropologicum 01/2009; 33(2):391-396. · 0.61 Impact Factor
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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.
    Journal of endocrinological investigation 01/2009; 32(1):18-22. DOI:10.1007/BF03345672 · 1.55 Impact Factor
  • 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.
    European Journal of Endocrinology 01/2009; 160(3):381-5. DOI:10.1530/EJE-08-0673 · 3.69 Impact Factor
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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.
    Medicine &amp Science in Sports &amp Exercise 12/2008; 41(1):137-143. DOI:10.1249/MSS.0b013e31818313e6 · 4.46 Impact Factor
  • 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.
    Homo: internationale Zeitschrift fur die vergleichende Forschung am Menschen 12/2008; 60(3):225-38. DOI:10.1016/j.jchb.2008.05.004 · 0.96 Impact Factor
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    ABSTRACT: The association of body fat mass (FM) with bone mineral mass (BMC) and bone mineral density (BMD) has been attributed to a mechanical load exerted on the skeleton by FM and by the effect of different hormones. The aim of the present study was to determine whether there is a relationship between ghrelin, adiponectin, and leptin with BMC and BMD in healthy postmenopausal women (n = 88; age, 68.9 +/- 6.8 years; body mass index, 27.4 +/- 3.6 kg/m(2)). Body composition, BMC, and BMD were derived by dual-energy X-ray absorptiometry. Waist-to-hip (WHR) and waist-to-thigh (WTR) ratios were also obtained. Ghrelin was associated with total BMC (beta = -0.945; P = 0.0001), total BMD (beta = -0.959; P = 0.0001), lumbar spine BMD (beta = -0.945; P = 0.0001), and femoral neck BMD (beta = -0.957; P = 0.0001), and remained associated (P < 0.041) in different analyses that controlled for measured body composition and hormonal and insulin resistance values. However, the associations between ghrelin and measured bone mineral values were no longer significant (P > 0.149) when adjusted for body fat distribution values (WHR, WTR). Adiponectin was significantly related to total BMC (beta = -0.931; P = 0.0001), total BMD (beta = -0.940; P = 0.0001), lumbar spine BMD (beta = -0.937; P = 0.0001), and femoral neck BMD (beta = -0.940; P = 0.0001) values, and these relationships remained significant (P < 0.019) after adjusting for measured body fat, hormonal, and insulin resistance values but not when adjusted for fat-free mass (FFM; P > 0.106). In addition, significant associations of leptin with total BMC (beta = 0.912; P = 0.0001), total BMD (beta = 0.907; P = 0.0001), lumbar spine BMD (beta = 0.899; P = 0.0001), and femoral neck BMD (beta = 0.906; P = 0.0001) were found. These associations remained significant (P < 0.010) in different analyses that controlled for hormonal and insulin resistance values, but the associations between leptin and bone mineral values were no longer significant (P > 0.145) when adjusted for specific body composition values (WHR, WTR, FM, and FFM). In conclusion, it appears that the influence of plasma ghrelin, adiponectin, and leptin levels on BMC and BMD values is mediated or confounded by the specific body composition parameters in healthy postmenopausal women.
    Journal of Bone and Mineral Metabolism 11/2008; 26(6):618-23. DOI:10.1007/s00774-008-0861-5 · 2.11 Impact Factor
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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«.
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    ABSTRACT: The aim of this study was to investigate plasma IL-6, TNF-alpha, leptin and ghrelin concentrations during high-volume training. Eight trained male rowers participated. Fasting blood was sampled before (T1) and after (T2) increased training volume and after recovery period (T3). Two-hour rowing was performed at T1, T2 and at T3 with blood samples before, POST and POST 30'. Decrease in fasting leptin was observed at T2 (from 1.31 (0.53) to 0.93 (0.27) ng ml(-1); P < 0.05). Leptin was also significantly decreased at POST and POST 30 exercise compared to PRE test at T2. At T2 POST 30' leptin was significantly lower compared to corresponding value at T1. There were no significant post-exercise changes in ghrelin at T2 compared to T1 and T3. TNF-alpha was significantly increased POST exercise only at T2. In conclusion, high-volume training causes alterations of post exercise leptin and TNF-alpha, while increases in ghrelin are down regulated.
    Arbeitsphysiologie 08/2008; 104(5):839-46. DOI:10.1007/s00421-008-0839-y · 2.30 Impact Factor
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    ABSTRACT: The aim of this study was to investigate possible relationships between different right-hand finger-length ratios and different fasting hormone concentrations in young swimmers. Fifty-five young swimmers participated in this study (26 boys and 29 girls, aged 10-17 years). The original method of Visnapuu and Jürimäe (J Strength Cond Res 21:923-929, 2007) was used for the measurement of length parameters of the hand. The following finger-length ratios were calculated: 1D:2D, 1D:3D, 1D:4D, 1D:5D, 2D:3D, 2D:4D, 2D:5D, 3D:4D, 3D:5D, and 4D:5D. All finger-length ratios were significantly higher in girls compared with boys. Ghrelin, leptin, testosterone in boys, estradiol in girls, insulin-like growth-factor I (IGF-I), IGFBP-3, and insulin were analyzed. Leptin and insulin concentrations were lower in boys compared with girls. In both groups, the relationships between finger-length ratios and basic anthropometric parameters were not significant. In girls, estradiol correlated negatively with 2D:3D (r = -0.51) and 2D:4D (r = -0.49) finger ratios. In boys, ghrelin concentration correlated with most of the finger-length ratios (r = 0.37-0.40). In girls, the relationship of ghrelin with the 2D:3D (r = 0.45) and 2D:4D (r = 0.48) finger ratios was significant. In boys, but not in girls, IGF-I (r = 0.42) and IGFBP-3 (r = 0.44) correlated only with the 2D:4D finger ratio. Leptin and insulin did not correlate with the finger-length ratios. In boys, the most important hormone to characterize several finger-length ratios was ghrelin (13.7-15.6% variance accounted for). Ghrelin and testosterone together accounted for 20.3% (R (2) x 100) of the variance in the 2D:4D ratio. In girls, estradiol was correlated with the 2D:3D ratio (25.7%) and estradiol in combination with ghrelin with the 2D:4D ratio (30.0%). In conclusion, ghrelin appears to be a further biochemical parameter in addition to the sex steroids which correlated with different digit-length ratios at least in boys.
    Arbeitsphysiologie 07/2008; 104(3):523-9. DOI:10.1007/s00421-008-0801-z · 2.30 Impact Factor
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    ABSTRACT: The aim of this study was to investigate the response of N-terminal propeptide of type I procollagen, crosslinked telopeptide of type I collagen and the growth hormone/insulin-like growth factor-I axis to acute aerobic exercise in boys at different pubertal stages The subjects were 60 healthy boys (group I - Tanner stage 1, N=20; group II - Tanner stages 2 and 3, N=20; group III - Tanner stages 4 and 5, N=20) who exercised 30 minutes at constant load on cycle ergometer at the level of ~95% of their individual ventilatory threshold. Venous blood samples were obtained before, immediately after and after 30 minutes of recovery for the measurement of serum testosterone, growth hormone (GH), insulin-like-growth factor-I, insulin-like-growth factor binding protein-3, N-terminal propeptide of type I procollagen (PINP) and crosslinked telopeptide of type I collagen. Acute exercise did not affect significantly serum testosterone, insulin-like-growth factor-I, insulin-like-growth factor binding protein-3 or bone turnover markers concentrations in any of study groups. The rise in growth hormone concentration during exercise was highest in group III (62.3+/-41.7 mU/L vs 15.5+/-11.4 in group I and 41.8+/-20.0 in group II). The increment in serum growth hormone level during exercise was positively correlated (r=0.64; P<0.001) to basal serum testosterone concentration. It can be concluded that growth hormone response to exercise was directly dependent on serum testosterone concentration. Acute exercise did not affect serum testosterone, insulin-like-growth factor-I, insulin-like-growth factor binding protein-3 or bone markers levels.
    The Journal of sports medicine and physical fitness 06/2008; 48(2):266-71. · 0.76 Impact Factor
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    Toivo Jürimäe, Tanya Hurbo, Jaak Jürimäe
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    ABSTRACT: The aim of this study was to determine how the legs bone mineral density (BMD) is influenced by anthropometry and vertical jumping height in prepubertal children. In total, 64 8-11-year-old schoolchildren (27 boys and 37 girls) were studied. All children were at Tanner stage 1. The subjects' height and body mass were measured and BMI calculated. The following anthropometric parameters directly connected with leg were measured: skinfolds--front thigh and medial calf girths--gluteal, thigh, mid-thigh, calf and ankle; lengths--iliospinale height, trochanterion height, trochanteriontibiale laterale, tibiale-laterale height and tibiale mediale-spyrion tibiale; and breadths--biiliocristal, foot length and biepicondylar femur. Total body and legs fat mass and fat %, lean body mass (LBM) and both legs BMD were measured by DXA. Maximal jumping height was measured on the contact mat. Stepwise multiple regression analysis indicated that body height in boys (54.6%; R2 x 100) and body mass in girls (57.3%) were the most important basic anthropometric parameters that influenced BMD in legs. From the measured skinfolds, that of the front thigh characterized legs BMD by 24.9-35.6%. From the girths, the most important parameter to characterize legs BMD was that of calf (50.0-59.1%). Tibiale laterale height was the only length parameter which was highly related with legs BMD (51.1-54.5%). Biepicondylar femur was the most important breadth parameter which characterized legs BMD (51.0-54.8%). Femur breadth and tibiale-laterale height were selected (68.7%) in boys, and tibiale-laterale height and front thigh skinfold thickness (66.0%) in girls when all measured leg anthropometric parameters were analyzed together. From the body composition parameters, the most important parameter to characterize legs BMD was legs LBM (48.9-59.5%). Jumping height did not correlate with legs BMD in any studied groups. In summary, the present study demonstrated that legs LBM together with tibiale-laterale height are the main predictors of legs BMD in prepubertal children.
    Collegium antropologicum 04/2008; 32(1):61-6. · 0.61 Impact Factor
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    ABSTRACT: The study of somatotypes can contribute to the understanding of variability in human body build. The aim of this study was to compare the somatotypes of Italian and Estonian schoolchildren in order to evaluate factors that might lead to variability in somatotypes. The sample consisted of 762 Italian and 366 Estonian children aged 6-11 years. They were somatotyped by the Heath-Carter anthropometric method. Data on organised extra-curricular physical activity and hours of weekly training were also collected. One-way ANOVA was used to evaluate country-related variations of somatotype in each age/sex group, while factorial ANOVA was used to test the influence of country and organised physical activity on the variability of the anthropometric characteristics and somatotype components. There are significant differences in mean somatotypes between the Italian and Estonian children in many age classes and a different constitutional trend in children from the two different countries is observed. The Italian children are more endomorphic and less mesomorphic and ectomorphic than the Estonian children. On the other hand, it emerges from factorial ANOVA, that the somatotype components do not present significant variations related to organised physical activity and to the interaction between the country of origin and sport practice. Moreover, the results of the forward stepwise discriminant analyses show that mesomorphy is the best discriminator between the two countries, followed by ectomorphy. Our findings suggest that the observed differences between Italian and Estonian children could be related mainly to country rather than to the practice of organised physical activity in the two countries.
    HOMO - Journal of Comparative Human Biology 02/2008; 59(5):383-96. DOI:10.1016/j.jchb.2007.07.001 · 0.73 Impact Factor
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    ABSTRACT: The aim of this study was to investigate responses of ghrelin, leptin, and adiponectin to a weight reduction period of 10 weeks in male subjects with high lean body mass and low body fat values. Fourteen male bodybuilders (7 competitors: 28.3 +/- 10.3 years, 175.3 +/- 5.4 cm, 82.2 +/- 9.3 kg; 7 controls: 22.4 +/- 3.0 years, 182.4 +/- 6.9 cm, 85.3 +/- 10.5 kg) participated in this study. The subjects were tested 3 times: 11 weeks (TEST1), 5 weeks (TEST2), and 3 days (TEST3) before the national championships. Testing procedure included dual-energy x-ray absorptiometry scan; calculation of daily energy intake and expenditure; and venous blood sampling for fasting ghrelin, leptin, and adiponectin. In the competitors' group, a significant (P < .05) 4.1-kg loss of body fat was observed that resulted in 6.5% +/- 1.5% of the body fat at the end of the study. Ghrelin increased significantly by 20.4% by TEST2. By TEST3, ghrelin was further increased by 6% (P > .05). The pattern of leptin was opposite, with a significant 27.7% decrease at TEST2 and no further decrease at TEST3 (P > .05). No significant change was observed in adiponectin concentration during the study. In the control group, no significant changes in biochemical parameters were observed. In conclusion, ghrelin concentration significantly increases, but is suppressed in conditions of limited energy availability that is accompanied by significant body mass loss in male subjects with initial low body fat values.
    Metabolism 02/2008; 57(2):221-5. DOI:10.1016/j.metabol.2007.09.004 · 3.61 Impact Factor
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    Jaak Jürimäe, Toivo Jürimäe
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    ABSTRACT: It has been reported that the prevalence of amenorrhea in the general female population is 2-5% in young adult women, while this can be as high as 66% in certain sports events. Many investigations have found that prolonged amenorrhea in female athletes is associated with a reduction in bone mineral density (BMD). As exercise is an osteogenic stimulus in itself, it is possible that some bone loss due to amenorrhea may be off-set in areas of high mechanical stimulus. However, BMD in female athletes is dependent on multiple factors and physical activity per se is not always protective for bone. Some of the factors that impact BMD include the nature of the sport discipline, the extent of energy deprivation, the changes in body composition and also various hormones. However, as the measurement of BMD represents only a static assessment of bone health, a more dynamic nature of the bone could be obtained by measuring the biochemical markers of bone forma-tion and resorption. This review focuses on: 1) the impact of different mechanical loading on bone turnover markers in female athletes; and 2) the hormonal factors that influence these bone turnover markers. It has to be taken into account that the beneficial effects of increased mechanical loading from different athletic activities do not always appear to protect against the effects of possible amenorrhea on BMD in female ath-letes. Female athletes should be monitored at regular intervals to understand better the influence of a high training load on different hormonal markers that are responsive for the bone health in these athletes.
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    ABSTRACT: The use of the heart rate turn point (HRTP) to set target heart rate (THR) for prolonged rowing ergometer (E) and single scull rowing (R) was evaluated. Ten trained subjects (age 21.3 +/- 4.0 yrs; VO (2max) 4.77 +/- 0.62 l . min-1) performed incremental exercise tests and 30-min prolonged E and R. Expired air and heart rate (HR) were measured continuously. During E and R, blood lactate concentration (La) was measured at rest and after 5, 10, 20, and 30 min. HRTP and V (E)TP (2) were determined as the deflection point of the heart rate performance curve and the second TP in minute ventilation (V. (E)). No significant differences were found for work rate (W), HR, and VO (2) between HRTP and V. (E)TP (2) and they were significantly related (r = 0.94, p < 0.001; r = 0.96, p < 0.001). Mean HR, VO (2), VCO (2), and V. (E) were not significantly different between E and R. La remained at a steady state in both E and R but was slightly higher in E. Tidal volume (V (T)) was found to be lower and breathing rate (BR) was significantly higher in R. HR at HRTP from an incremental rowing ergometer exercise test is valid to establish a THR consistent with constant metabolic training intensity in prolonged ergometer and single scull rowing.
    International Journal of Sports Medicine 11/2007; 28(11):964-9. DOI:10.1055/s-2007-965074 · 2.37 Impact Factor
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    ABSTRACT: We examined the effect of regular physical activity on plasma ghrelin concentration after onset of puberty in girls. In addition, we also examined the association of fasting plasma ghrelin concentration with various plasma biochemical, body composition, and aerobic capacity variables in healthy adolescent girls. Fifty healthy schoolgirls ages 11 to 16 yr were divided either into a physically active (N = 25) or a physically inactive (N = 25) group. The physically active group consisted of swimmers who had trained on an average of 6.2 +/- 2.0 h.wk(-1) for the last 2 yr, whereas the inclusion criterion for the physically inactive group was the participation in physical education classes only. The subjects were matched for age (+/- 1 yr) and body mass index (BMI; +/- 2 kg.m(-2)). Maturation I group (14 matched pairs) included pubertal stages 2 and 3, and maturation II group (11 matched pairs) included pubertal stages 4 and 5. Physically active girls had significantly higher (P < 0.05) mean plasma ghrelin levels than the physically inactive girls (maturation I: 1152.1 +/- 312.9 vs 877.7 +/- 114.8 pg.mL(-1); maturation II: 1084.0 +/- 252.5 vs 793.4 +/- 164.9 pg.mL(-1)). Plasma ghrelin concentration was negatively related to percent body fat, fat mass, peak oxygen consumption per kilogram of body mass, leptin, estradiol, insulin, and insulin-like growth factor-I (IGF-I) (r > -0.298; P < 0.05). Multivariate linear regression analysis to determine the predictors of ghrelin concentration using the variables that were significantly associated with ghrelin concentration demonstrated that plasma IGF-I was the most important predictor of plasma ghrelin concentration (beta = -0.396; P = 0.008). Regular physical activity influences plasma ghrelin concentrations in girls with different pubertal maturation levels. Plasma IGF-I concentration seems to be the main determinant of circulating ghrelin in healthy, normal-weight adolescent girls.
    Medicine &amp Science in Sports &amp Exercise 11/2007; 39(10):1736-41. DOI:10.1249/mss.0b013e31812e5294 · 4.46 Impact Factor
  • International Journal of Sports Medicine 11/2007; · 2.37 Impact Factor
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    ABSTRACT: The purpose of the present study was to investigate the use of electromyographic signals (EMG), to determine the EMG threshold (EMGT) in four lower extremity muscles and to compare these thresholds with the second ventilatory threshold (VT2) in subjects participating in different sports and at different performance levels. Forty-nine subjects (23.8 +/- 5.7 years, 182.7 +/- 5.3 cm, 79.1 +/- 8.6 kg) including eleven cyclists, ten team-handball players, nine kayakers, eight power lifters and eleven controls were investigated utilizing a cycle ergometer. Respiratory gas exchange measures were collected and EMG activity was continuously recorded from four muscles (vastus lateralis, vastus medialis, biceps femoris and gastrocnemius lateralis). The VO(2)max averaged 56.1 +/- 11.1 ml kg(-1) min(-1), the average aerobic power was 348.5 +/- 61.0 W and the corresponding VT2 occurred at 271.4 +/- 64.0 W. The EMGT ranged from 80 to 98% of power output for the different muscles. The VT2 and EMG thresholds from four different muscles were not different. When thresholds were analyzed among different groups of subjects, no significant difference was observed between VT2 and EMGT despite threshold differences between the groups. All four EMGT were significantly related to maximal aerobic power (r = 0.73-0.83) and were highly correlated to each other (r = 0.57-0.88). In conclusion, EMGT can be used to determine the VT2 for individuals independent of sport specificity or performance level.
    Arbeitsphysiologie 11/2007; 101(3):341-6. DOI:10.1007/s00421-007-0509-5 · 2.30 Impact Factor
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    ABSTRACT: The aim of the study was to investigate the relationships between handgrip and pinch strength values with basic body (body height, body mass, BMI) and with specific hand anthropometric parameters (fingers spans, lengths and perimeters) in prepubertal children. Body height, body mass and five fingers spans, lengths and perimeters were measured in 461 6-10 year old Estonian children according to Visnapuu & Jürimäe (2007). BMI was calculated (kg/m2). The maximal handgrip strength of the right and left hand was measured with hand dynamometer. The right and left key and tip pinch were measured with a pinch gauge. Body height, as a rule, in combination with BMI, was the strongest predictor of handgrip strength, especially in older children (about 40-60 % of the total variance, R2 x 100). From the hand anthropometry, the most important span parameter was FS2 (see explanations in the methods), which explained about 10-50% (R2 x 100) of the total variance. In older groups, the FS1 and FS3 were added to the models. From the length parameters, the most important was IFL, which in younger groups together with MFL explained 10-30% of the total variance, and in older groups the addition of RFL increased the influence to 45% (R2 x 100). From the perimeters, the most important one was P2 which explained the variability of the handgrip strength in younger groups by 15-30% (R2 x 100) and in older groups together with P3 and P4 even 30-40%. In children, the basic anthropometric parameters (body height and BMI) contribute more to the prediction of handgrip strength than the specific anthropometric parameters. With increasing age the contribution of basic and specific hand anthropometry increases and the relation between anthropometry and handgrip strength is stronger in boys compared with girls. The relation of basic and hand anthropometry to the tip and key pinch strength is relatively low.
    Anthropologischer Anzeiger 09/2007; 65(3):293-302. · 0.54 Impact Factor
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    J Jürimäe, T Jürimäe
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    ABSTRACT: Adipose-modulated biochemical signal that explains some of the association between fat mass and bone mineral density (BMD) is adiponectin. The results demonstrated an independent association between adiponectin and BMD, while the influence of adiponectin on bone mineral content is mediated by fat free mass in middle-aged women. Positive association between fat mass (FM) and bone mineral density (BMD) is mediated by biochemical factors. The relationship between plasma adiponectin concentration and BMD in 98 sedentary premenopausal women aged 38-49 years with a body mass index range of 20.0-42.1 kg/m(2) was examined. Different body composition and blood biochemical parameters were measured to adjust for possible confounding variables. The association between adiponectin and BMD values (total BMD: beta = -0.919; p = 0.0001, femoral neck BMD: beta = -0.925; p = 0.0001 and lumbar spine BMD: ss = -0.912; p = 0.0001) was independent of the influences that measured body composition, hormonal and insulin resistance factors may exert on BMD (p < 0.02). However, adiponectin explained only 3-12% of the variations in measured BMD variables. Similarly, adiponectin was associated with total bone mineral content (BMC; beta = -0.911; p = 0.0001) and remained associated in different analyses that controlled for possible confounding parameters (p < 0.01). However, the association between adiponectin and total BMC was no longer significant when adjusted for fat free mass (FFM; p > 0.21). Adiponectin is an independent predictor of BMD, while its independent contribution to the interindividual variance in measured values is only modest. The influence of adiponectin on total BMC is mediated or confounded by FFM in middle-aged premenopausal women.
    Osteoporosis International 09/2007; 18(9):1253-9. DOI:10.1007/s00198-007-0365-5 · 4.17 Impact Factor

Publication Stats

1k Citations
217.66 Total Impact Points

Institutions

  • 1998–2015
    • University of Tartu
      • • Faculty of Exercise and Sports Sciences
      • • Institute of Sport Pedagogy and Coaching
      Dorpat, Tartu, Estonia
  • 2009
    • Medical University of Graz
      • Institute of Physiological Chemistry
      Gratz, Styria, Austria
  • 2007
    • University of Bologna
      • Department of Experimental Evolutionary Biology BES
      Bologna, Emilia-Romagna, Italy