Fabiana Andrade Machado

Validade das equações preditivas da frequência cardíaca máxima para crianças e adolescentes

Metodos: Un test progresivo de esfuerzo maximo fue realizado en 69 ninos con edades entre los 10 y los 16 anos, aparentemente sanos y activos. La velocidad inicial del test fue de 9 km/h con incrementos de 1 km/h a cada tres minutos. El test se mantuvo hasta el agotamiento voluntario, considerando como FCmax la mayor frecuencia cardiaca alcanzada durante el test. La FCmax medida se comparo con los valores previstos por las ecuaciones “220 edad” y “208 (0,7 x edad)” a traves de ANOVA, medidas repetidas.

Validity of maximum heart rate prediction equations for children and adolescents.

Metodos: Un test progresivo de esfuerzo maximo fue realizado en 69 ninos con edades entre los 10 y los 16 anos, aparentemente sanos y activos. La velocidad inicial del test fue de 9 km/h con incrementos de 1 km/h a cada tres minutos. El test se mantuvo hasta el agotamiento voluntario, considerando como FCmax la mayor frecuencia cardiaca alcanzada durante el test. La FCmax medida se comparo con los valores previstos por las ecuaciones “220 edad” y “208 (0,7 x edad)” a traves de ANOVA, medidas repetidas.

Incremental test design, peak ‘aerobic’ running speed and endurance performance in runners

OBJECTIVES Peak running speed obtained during an incremental treadmill test (Vpeak) is a good predictor of endurance run performance. However, the best-designed protocol for Vpeak determination and the best Vpeak definition remain unknown. Therefore, this study examined the influence of stage duration and Vpeak definition on the relationship between Vpeak and endurance run performance. DESIGN Relationship. METHODS Twenty-seven male, recreational, endurance-trained runners (10-km running pace: 10-17 k mh(-1)) performed, in counterbalanced order, three continuous incremental treadmill tests of different stage durations (1-, 2-, or 3-min) to determine Vpeak, and two 5-km and two 10-km time trials on a 400-m track to obtain their 5-km and 10-km run performances. Vpeak was defined as either (a) the highest speed that could be maintained for a complete minute (Vpeak-60 s), (b) the speed of the last complete stage (Vpeak-C), or (c) the speed of the last complete stage added to the multiplication of the speed increment by the completed fraction of the incomplete stage (Vpeak-P). RESULTS The Vpeak determined during the 3-min stage duration protocol was the most highly correlated with both the 5-km (r=0.95) and 10-km (r=0.92) running performances and these relationships were minimally influenced by the Vpeak definition. However, independent of the stage duration, the Vpeak-P provided the highest correlation with both running performances. CONCLUSIONS Incremental treadmill tests comprising 3-min stage duration is preferred to 1-min and 2-min stage duration protocols in order to determine Vpeak to accurately predict 5-km and 10-km running performances. Further, Vpeak-P should be used as standard for the determination of Vpeak.

Longitudinal changes in cardiac autonomic function and aerobic fitness indices in endurance runners: A case study with a high-level team

Abstract To determine the effects of preparatory phase training on aerobic parameters, resting heart rate variability (HRV) and 5-km performance of high-level endurance runners and the relationship between the percentage change (% change) of resting HRV with the % change of aerobic parameters and 5-km performance. Six runners were assessed before and after seven weeks of training. The aerobic parameters were determined in an incremental test. The HRV was assessed by a heart rate monitor. Athletes performed a 5-km running test in a track. The analysis revealed ‘likely’ and ‘very likely’ improvements for velocity associated with maximal oxygen uptake ( O2max) (20.0±1.0 km·h−1 to 21.2±0.6 km·h−1) and 5-km performance (18.0±0.4 km·h−1 to 18.9±0.7 km·h−1), respectively, as well as ‘likely’ decrease in high frequency (41.4±18.5 nu to 30.4±14.3 nu), and increase in low frequency (58.5±18.5 nu to 69.6±14.3 nu) band densities. The variation in the velocity associated with O2max showed the highest correlation with 5-km performance (r=0.95). The % change in the square root of the mean sum of the squared differences between R–R intervals and standard deviation 1 were highly correlated with variation in 5-km performance (r=0.69 and 0.66). Changes in the velocity associated with O2max and vagally mediated HRV were highly associated with 5-km running performance within the investigated team. These results have important implications because these parameters can be assessed longitudinally to monitor adaptation to training.

Reliability of peak running speeds obtained from different incremental treadmill protocols.

Abstract This study compared the values and reliability of peak running speeds from incremental treadmill protocols with different speed increments. Thirty-one men, recreational, endurance-trained runners performed, in an alternate order, three continuous tests with different speed increments (0.5, 1 and 2 km · h−1). The tests were repeated using the same order. Peak speed was identified as (1) the greatest speed that could be maintained for a complete minute (Vpeak-60s), (2) the speed of the last complete stage (Vpeak-C) and (3) the speed of the last complete stage added to the product of the speed increment and the completed fraction of the incomplete stage (Vpeak-P). The Vpeak-P was the most reliable, independent of the incremental test protocol (1.5% ≤ CV ≤ 1.8%), and differently from Vpeak-C (1.8% ≤ CV ≤ 2.6%) and Vpeak-60s (1.6% ≤ CV ≤ 3.8%), the Vpeak-P was only slightly influenced by the incremental test protocol. The results suggest that Vpeak-P should be used to assess aerobic capability and monitor training effects and that other determinations of peak speed should be avoided.

Influence of regression model and incremental test protocol on the relationship between lactate threshold using the maximal-deviation method and performance in female runners

Abstract This study examined the influence of the regression model and initial intensity of an incremental test on the relationship between the lactate threshold estimated by the maximal-deviation method and the endurance performance. Sixteen non-competitive, recreational female runners performed a discontinuous incremental treadmill test. The initial speed was set at 7 km · h−1, and increased every 3 min by 1 km · h−1 with a 30-s rest between the stages used for earlobe capillary blood sample collection. Lactate-speed data were fitted by an exponential-plus-constant and a third-order polynomial equation. The lactate threshold was determined for both regression equations, using all the coordinates, excluding the first and excluding the first and second initial points. Mean speed of a 10-km road race was the performance index (3.04 ± 0.22 m · s−1). The exponentially-derived lactate threshold had a higher correlation (0.98 ≤ r ≤ 0.99) and smaller standard error of estimate (SEE) (0.04 ≤ SEE ≤ 0.05 m · s−1) with performance than the polynomially-derived equivalent (0.83 ≤ r ≤ 0.89; 0.10 ≤ SEE ≤ 0.13 m · s−1). The exponential lactate threshold was greater than the polynomial equivalent (P < 0.05). The results suggest that the exponential lactate threshold is a valid performance index that is independent of the initial intensity of the incremental test and better than the polynomial equivalent.

The Dmax is highly related to performance in middle-aged females.

The present study examined whether the running speed at the lactate threshold estimated by the maximal deviation method (LT (Dmax)) is highly correlated and in agreement with 10-km road race performance (S (10 km)) in middle-aged female runners. Additionally, the LT (Dmax) was compared with the visual detection of the inflection point (LT (Visual)), the fixed lactate level of 4 mmol.L (-1) (LT (4)) and the peak speed (S (peak)) in relation to performance. Sixteen middle-aged, recreational female runners performed a discontinuous, incremental treadmill test. The initial speed was set at 7 km.h (-1), and this speed was increased every 3 min by 1 km.h (-1) with a 30-s rest between the stages used for earlobe capillary blood sample collection. All of the participants took part in the same local 10-km road race, and S (10 km) mean speed was calculated. The speeds (mean ± SD) were 10.5 ± 1.0 (S (10 km)), 10.5 ± 1.0 (LT (Visual)), 10.9 ± 0.9 (LT (Dmax)), 11.4 ± 1.3 (LT (4)) and 13.5 ± 1.1 km.h (-1) (S (peak)). The LT (Dmax) had the narrowest limits of agreement (0.3 ± 0.4 km.h (-1)) and was the most highly correlated with the S (10 km) ( R=0.98), followed by the S (peak) ( R=0.95), LT (4) ( R=0.85) and LT (Visual) ( R=0.81). In conclusion, the LT (Dmax) should be more widely used to estimate long-distance performance and to verify improvements in training.

Reliability of the Heart Rate Variability Threshold using Visual Inspection and Dmax Methods

The purpose of this study was to compare heart rate variability threshold (HRVT) in 6 incremental tests and test its reproducibility using visual inspection and Dmax methods for root mean square of successive differences between the adjacent normal R-R intervals (RMSSD), standard deviation of the normal RR interval (SDNN) and standard deviation of instantaneous beat-to-beat variability (SD1). 12 adult males performed an incremental test to volitional fatigue on a cycle simulator during 6 visits to the laboratory. The initial test load was 25 W, and the intensity was increased by 25 W every 3 min until volitional fatigue set in. The HRV during the incremental test was analyzed using the RMSSD, SDNN and SD1 indices and the determination of HRVT was performed using 2 methods: visual inspection and Dmax. The results demonstrated that the SD1 and RMSSD indices, determined by the visual inspection method, presented the highest reproducibility of HRVT when compared with the other indices and methods. We concluded that the best method for determining HRVT was the technique using the point of stabilization by visual inspection in the SD1 and RMSSD indices during the incremental test, due to its high reproducibility, lower coefficient of variation and increment size.

Effect of stage duration on maximal heart rate and post-exercise blood lactate concentration during incremental treadmill tests.

OBJECTIVES This study compared the responses during maximal incremental treadmill tests of 1-min, 2-min, and 3-min stage durations mainly in terms of maximal heart rate (HRmax) and peak blood lactate concentration (LApeak). DESIGN Repeated-measures. METHODS Thirty-four male, recreational, endurance-trained runners (40±13 years) performed three tests on a motorized treadmill. The tests started at 8kmh(-1) with increments of 1kmh(-1) every 1min for the short-stage protocol, every 2min for the intermediate-stage protocol, and every 3min for the long-stage protocol. LApeak was defined for each subject as the highest value among the lactate concentrations determined at the end of each test and at the third, fifth and seventh minutes after test, during passive recovery. RESULTS Analysis of variance revealed a significant effect of the stage duration on the HRmax (p=0.003) and LApeak (p=0.001). The HRmax was higher in the intermediate-stage compared to the short-stage protocol (184.8±12.7 vs. 181.8±12.1beatsmin(-1), p<0.001), but no significant differences were found between the long-stage (183.1±12.1beatsmin(-1)) and the intermediate-stage or short-stage protocols (p>0.05). The LApeak was lower in the long-stage compared to the short-stage and intermediate-stage protocols (7.9±2.2 vs. 9.4±2.2 and 9.2±1.9mmolL(-1), respectively, p<0.05). Further, blood lactate reached peak concentration at the fifth minute after test for all the protocols. CONCLUSIONS Thus, HRmax and LApeak depend on the stage duration of the incremental test, but the moment at which blood lactate reaches peak concentration is independent of the duration. Further, we suggest 2-min stage duration protocols to determine HRmax.

Peak velocity and its time limit are as good as the velocity associated with VO2max for training prescription in runners

This study compared the effects of 4 weeks of training prescribed by peak velocity (V peak ) or velocity associated with maximum oxygen uptake (vVO 2max ) in moderately trained endurance runners. Study participants were 14 runners (18–35 years) randomized into 2 groups, named group VO 2 (GVO 2 ) and group V peak (GVP). The GVO 2 had training prescribed by vVO 2max and its time limit (t lim ), whereas the GVP had training prescribed by V peak and its t lim . Four tests were performed on a treadmill: 2 maximum incremental for V peak and vVO 2max and 2 for their t lim . Performance (10 km) was evaluated on a 400 m track. Evaluations were repeated after 4 weeks of endurance training. The results showed a significant effect of training on V peak [GVP (16.7±1.2 – 17.6±1.5 km . h −1 ), GVO 2 (17.1±1.9–17.7±1.6 km·h −1 )]; vVO 2max [GVP (16.4±1.4–17.0±1.3 km·h −1 ), GVO 2 (17.2±1.7–17.5±1.9 km·h −1 )]; and 10 km performance [GVP (41.3±2.4–39.9±2.7 min), GVO 2 (40.1±3.4–39.2±2.9 min)]. The V peak highly correlated with performance in both pre- and post-training in GVP (–0.97;–0.86) and GVO 2 (–0.95;–0.94), as well as with vVO 2max in GVP (–0.82;–0.88) and GVO 2 (–0.99; –0.98). It is concluded that training prescribed by V peak promoted similar improvements compared to training prescribed by vVO 2max . The use of V peak is recommended due to its practical application and the low cost of determination.