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Study aim: To determine the effects of oral L-arginine supplementation on vasodilation, blood flow and maximum oxygen uptake (O2max) in soccer players.Material and methods: A group of 24 healthy male soccer players aged 20 - 26 years volunteered to participate in the study. The subjects were randomly assigned into 3 groups: experimental, placebo and control. Experimental group was given L-arginine (6 g orally) and the placebo group - starch (6 g orally) daily for a week; subjects from the control group remained untreated. Before the test and at the end of the week blood samples were collected, and systemic blood pressures, blood flows and maximal oxygen uptake (O2max, by Queens College step test) were recorded. Blood samples were assayed for HDL, LDL, triglyceride and urea concentrations. The study was conducted in a randomised, single-blinded, placebo-controlled fashion consisting of 7-day treatment periods.Results: Oral supplementation of L-arginine significantly (p<0.01) decreased blood pressure indices and increased O2max (p<0.01), blood flow (p<0.05), femoral artery diameter (p<0.05) and urea levels (p<0.05). There was no change in blood lipid levels (p<0.05). No significant changes were noted in the placebo and control groups.Conclusions: Oral supplementation of L-arginine may have beneficial effect on vasodilation and O2max, therefore may increase the exercise capacity of soccer players.
Study aim: To examine the association between two submaximal (physical working capacity at a heart rate of 170 (PWC170) on cycle ergometer test and YMCA Step Test) and maximal measures (maximal oxygen uptake (VO2max)) of aerobic power, as well as to study the repeatability of the aforementioned submaximal measures in physically active female adolescents.Material and methods: Ten female adolescents, aged 13.4 ± 0.7 years old, all members of a local track and field sport club, performed the PWC170 and YMCA Step Test twice. The tests were separated by an interval of one week. During the second laboratory visit, VO2max was measured during a graded exercise test.Results: Considering the repeatability of submaximal measures, intraclass correlation coefficient was 0.89 (95% CI 0.55-0.97) and 0.91 (95% CI 0.65-0.98) in absolute and relative to body mass values of PWC170, while it was 0.69 (95% CI -0.27-0.92) with regard to heart rate at the end of step test and 0.78 (95% CI 0.11-0.95) at the end of the first minute of recovery after step test. PWC170 was associated significantly with VO2max in absolute values (r = 0.65, p = 0.04), but not with VO2max relative to body mass values (r = 0.44, p = 0.20). The corresponding relationships between relative PWC170 and VO2max were r = 0.39 (p = 0.27) and r = 0.60 (p = 0.06). Heart rate at the end of the step test was non-significantly related to VO2max in both absolute and relative values (r = -0.53, p = 0.12 and r = -0.61, p = 0.06), whereas respective values of heart rate at the end of the first minute after step test were r = -0.72 (p = 0.02) and r = -0.69 (p = 0.03).Conclusion: These submaximal measures appeared to be valid and reliable, and they were recommended for further use in similar population with the assumption that a familiarization session was preceded.
Objectives: The purpose of this study was to compare values of aerobic performance in the 1-mile run test (1-MRT) using different formulae. Material and Methods: Aerobic capacities of 351 male volunteers working for the Turkish National Police within the age range of 20-23 years were evaluated by the 1-MRT and the 20-metre shuttle run (20-MST). $\text{VO}_\text{2max}$ values were estimated by the prediction equations developed by George et al. (1993), Cureton et al. (1995) and Kline et al. (1987) for the 1-MRT and by Leger and Lambert (1982) for the 20-MST. Results: The difference between the results of the different formulae was significant (p = 0.000). The correlation coefficient between the estimated $\text{VO}_\text{2max}$ using Cureton's equation, George's equation, Kline's equation and the 20-MST were 0.691 (p < 0.001), 0.486 (p < 0.001) and 0.608 (p < 0.001), respectively. The highest correlation coefficient was between the $\text{VO}_\text{2max}$ estimated by the 20-MST and Cureton's equation. Similarly, the highest correlation coefficient (r = -0.779) was between the 1-mile run time and the $\text{VO}_\text{2max}$ estimated by Cureton's equation. Conclusions: When analysing more vigorous exercise than sub-maximal exercise, we suggest that Cureton's equation be used to predict the $\text{VO}_\text{2max}$ from 1-mile run/walk performance in large numbers of healthy individuals with high $\text{VO}_\text{2max}$. This research compares the use of 3 different formulae to estimate $\text{VO}_\text{2max}$ from 1-mile run/walk performance in male law enforcement officers aged 20-23 years for the first time and reports the most accurate formula to use when evaluating aerobic capacities of large numbers of healthy individuals.
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