Jorge Roberto Perrout de Lima

Heart Rate Monitoring in Soccer: Interest and Limits During Competitive Match Play and Training, Practical Application.

Abstract Alexandre, D, Da Silva, C, Hill-Haas, S, Wong, DP, Natali, AJ, De Lima, JRP, Filho, MGB, Marins, JCB, Garcia, ES, and Chamari, K. Heart rate monitoring in soccer: Interest and limits during competitive match play and training–Practical application. J Strength Cond Res 26(10): 2890–2906, 2012—The identification of physiological loads imposed by soccer training or match play reveals essential information, which may help improve training and recovery strategies. Until today, the use of heart rate (HR) monitoring is not standardized in soccer. Thus, the aim of this review was to analyze, determine and compare the exercise intensity (EI) monitored by HR in professional, youth, and recreational soccer players during matches and training sessions using a meta-analysis. Heart rate is one of the most common physiological variables used to determine exercise internal training load. The mean EI recorded during competitive matches was described as 70–80% of V[Combining Dot Above]O2max or 80–90% of maximal heart rate (HRmax), independent of the playing level. With respect to HR training zones, approximately 65% of the total match duration is spent at intensity of 70–90% HRmax and rarely below 65% HRmax. However, although HRmax is mostly employed in the literature, monitoring EI should be expressed in relation to reserve heart rate, as it was described as a more reliable indicator of HR, allowing interindividual comparisons. The HR response according to the playing position indicates that midfielders are characterized by the highest EI, followed by forwards and fullbacks. Moreover, in the second half of the match, the EI is lower than that observed during the first half; this reduction could be correlated with the level of the players physical conditioning. Consequently, coaches may favor the use of interval training or small-sided training games because these are shown to improve both aerobic capacity and the ability to repeat high-intensity actions. Small-sided games allow reaching similar HR responses to those found during interval training and match play but with greater heterogeneity values. Future investigations should include a larger sample of players with special reference to playing position and the expression of EI in percentage of the reserve heart rate, analyzing the possible intergender differences in HR response.

Absence of parasympathetic reactivation after maximal exercise.

The ability of the human organism to recover its autonomic balance soon after physical exercise cessation has an important impact on the individuals health status. Although the dynamics of heart rate recovery after maximal exercise has been studied, little is known about heart rate variability after this type of exercise. The aim of this study is to analyse the dynamics of heart rate and heart rate variability recovery after maximal exercise in healthy young men. Fifteen healthy male subjects (21·7 ± 3·4 years; 24·0 ± 2·1 kg m−2) participated in the study. The experimental protocol consisted of an incremental maximal exercise test on a cycle ergometer, until maximal voluntary exhaustion. After the test, recovery R‐R intervals were recorded for 5 min. From the absolute differences between peak heart rate values and the heart rate values at 1 and 5 min of the recovery, the heart rate recovery was calculated. Postexercise heart rate variability was analysed from calculations of the SDNN and RMSSD indexes, in 30‐s windows (SDNN30s and RMSSD30s) throughout recovery. One and 5 min after maximal exercise cessation, the heart rate recovered 34·7 (±6·6) and 75·5 (±6·1) bpm, respectively. With regard to HRV recovery, while the SDNN30s index had a slight increase, RMSSD30s index remained totally suppressed throughout the recovery, suggesting an absence of vagal modulation reactivation and, possibly, a discrete sympathetic withdrawal. Therefore, it is possible that the main mechanism associated with the fall of HR after maximal exercise is sympathetic withdrawal or a vagal tone restoration without vagal modulation recovery.

Utilização do esforço percebido na determinação da velocidade crítica em corrida aquática

La relacion lineal entre la intensidad del ejercicio y la tasa de aumento de la actividad neuromuscular estimada por la electromiografia permite estimar el limite de fatiga que seria la intensidad que podria estar mantenida indefinidamente sin aumento de senales electromiograficos a largo plazo. Se planteo la hipotesis de que la percepcion subjetiva del esfuerzo tendria un comportamiento semejante a la activacion neuromuscular, y que el umbral del esfuerzo percibido (LEP), identificado de forma semejante al umbral de fatiga electromiografica, podria coincidir con la velocidad critica (VCrit). Trece individuos de ambos sexos (23 ± 2.5 anos) en una piscina de 15 ms de extension y 2.5 ms de profundidad, realizaron 3 tests exhaustivos de maraton acuatica para la determinacion de los parametros de velocidad critica, reportando el esfuerzo percibido (escala de Borg de 6 a 20 puntos) cada 15 min. Para identificacion del LEP, los coeficientes de inclinacion de las rectas de aumento del esfuerzo percibido en el tiempo (ordenada) y las velocidades utilizadas (abcisa) fueron ajustados a una funcion lineal que marcaba un punto de crecimiento de velocidad donde teoricamente el esfuerzo percibido estaria establecido indefinidamente. La VCrit fue estimada por las ecuasiones usadas en el modelo de la velocidad critica. Para comparacion de las estimativas de Vcrit, del LEP y de sus asociaciones, fue hecha ANOVA para medidas repetidas (p < 0.05) y calculada la correlacion de Pearson. Los datos obtenidos para la determinacion de VCrit se ajustaran a los criterios adoptados para la validacion del modelo, y la VCrit y LEP no presentaron diferencias estadisticas (0.23 ± 0.02 m/s x 0.24 +/- 0.03 m/s) y fueron significativamente correlacionados (r = 0.85). Estos resultados sugieren que el LEP parece representar la intensidad maxima de ejercicio en que las variables fisiologicas y sicofisicas encontrarian estabilidad, y que este indice puede ser utilizado para la determinacion de la VCrit.

Freqüência cardíaca máxima em esteira ergométrica em diferentes horários

The aim of this study was to compare the maximal heart rate (HRmax) in the Bruce test (TBruce) at different times of the day, since several measurements of the human performance present circadian variations which seem to follow the body temperature rhythm. Eleven male individuals, with 22.0 ± 1.6 years, physically active and from the intermediate chronotype were studied. The resting HR (HRres), maximal HR (HRmax), perceived exertion (PE) and time until exhaustion (TBruce) were observed. The Polar Vantage NV cardiofrequencymeter was used in order to measure the HR. The PE was obtained through the Borg’s scale (6-20). The protocol by Bruce for treadmill was applied until exhaustion, at 6 different times: 9:00; 12:00; 15:00; 18:00; 21:00 and 24:00 hours. The results were submitted to the variance analysis for repeated measurements, followed by Tukey test (p < 0.05) and the Cosinor adjustment for identification of rhythmic patterns. There was significant difference between the HRres of the 15:00 and 24:00 h (67.2 ± 6.9 and 60.4 bpm) and in the HR max of the 12:00 and 24:00 hours (197.4 ± 7.9 and 191.3 ± 5.8 bpm). No difference was identified in the PE and in the TBruce. Rhythmicity was found in 1 individual in the HRres, 1 in the HRmax and 2 in the TBruce. It was concluded that in uncontrolled conditions, whenever daily activities are kept, both HRres and HRmax present lower indices around 24:00 hours, with no loss in the maximal aerobic performance and no PE alteration. These findings should be considered in the aerobic evaluation and in the exercises prescription at later times.Debido a que muchas medidas de desempeno humano presentan variaciones circadianas que parecen acompanar el ritmo de la temperatura corporal, el objetivo de este estudio ha sido el de comparar la frecuencia cardiaca maxima (FCmax) en el test de Bruce (TBruce) en diferentes horarios del dia. Fueron estudiados 11 individuos del genero masculino, con 22,0 ± 1,6 anos, fisicamente activos y de cronotipo intermedio. Se observo la FC de reposo (FCrep), FC maxima (FCmax), percepcion de esfuerzo (PE) y tiempo hasta la extenuacion (TBruce). Para medir la FC se uso el cardiofrecuencimetro Polar Vantage NV. La PE se obtuvo por la escala de Borg (6-20). Se aplico el protocolo de Bruce para cinta ergometrica, hasta la extenuacion, en 6 horarios distintos: 9:00, 12:00, 15:00, 18:00, 21:00 y 24:00 horas. Los resultados fueron sometidos a analisis de varianza para medidas repetidas, seguida del test de Tukey (p < 0,05) y al ajuste Cosinor para identificacion de los padrones ritmicos. Hubo diferencia significativa entre la FCrep de las 15:00 y 24:00 h (67,2 ± 6,9 y 60,4 ± 6,4 bpm) y en la FCmax de las 12:00 y 24:00 horas (197,4 ± 7,9 y 191,3 ± 5,8 bpm). No fue observada diferencia en la PE y en el TBruce. Se encontro ritmo en 1 individuo en la FCrep, 1 en la FCmax y 2 en el TBruce. A partir de esto se concluyo que, en condiciones no controladas, manteniendose las actividades diarias, tanto la FCrep, como la Fcmax, presentan valores mas bajos alrededor de las 24:00 horas, sin perdida en el desempeno aerobico maximo y sin alteracion de PE. Estos resultados deben ser considerados en la evaluacion aerobica y en la prescripcion de ejercicios en horarios mas tardios.

Pulmonary Oxygen Uptake Kinetics During Exercise in Subclinical Hypothyroidism

BACKGROUND Patients with subclinical hypothyroidism (SCH) have lower exercise tolerance, but the impact on oxygen uptake (VO2) kinetics is unknown. This study evaluated VO2 kinetics during and after a constant load submaximal exercise in SCH. METHODS The study included 19 women with SCH (thyrotropin (TSH)=6.87±2.88 μIU/mL, free thyroxine (fT4)=0.97±0.15 ng/dL) and 19 controls (TSH=2.29±0.86 μIU/mL, T4=0.99±0.11 ng/dL) aged between 20 and 55 years. Ergospirometry exercise testing was performed for six minutes with a constant load of 50 W, followed by six minutes of passive recovery. The VO2 kinetics was quantified by the mean response time (MRT), which is the exponential time constant and approximates the time needed to reach 63% of change in VO2 (ΔVO2). The O2 deficit-energy supplied by anaerobic metabolism at the onset of exercise-and O2 debit-extra energy demand during the recovery period-were calculated by the formula MRT×ΔVO2. Values are mean±standard deviation. RESULTS In the rest-exercise transition, patients with SCH showed slower VO2 kinetics (MRT=47±8 sec vs. 40±6 sec, p=0.004) and a higher oxygen deficit (580±102 mL vs. 477±95 mL, p=0.003) than controls respectively. In the exercise-recovery transition, patients with SCH also showed slower VO2 kinetics (MRT=54±6 sec vs. 44±6 sec, p=0.001) and a higher oxygen debit (679±105 mL vs. 572±104 mL, p=0.003). The VO2 kinetics showed a significant correlation with TSH (p<0.05). CONCLUSIONS This study demonstrates that women with SCH have the slowest VO2 kinetics in the onset and recovery of a constant-load submaximal exercise and highlights that this impairment is already manifest in the early stage of the disease.

Water Intake Accelerates Parasympathetic Reactivation After High-Intensity Exercise

UNLABELLED It has been shown that water intake (WI) improves postexercise parasympathetic recovery after moderate-intensity exercise session. However, the potential cardiovascular benefit promoted by WI has not been investigated after high-intensity exercise. PURPOSE To assess the effects of WI on post high-intensity parasympathetic recovery. METHODS Twelve recreationally active young men participated in the study (22 ± 1.4 years, 24.1 ± 1.6 kg.m(-2)). The experimental protocol consisted of two visits to the laboratory. Each visit consisted in the completion of a 30-min high-intensity [~80% of maximal heart rate (HR)] cycle ergometer aerobic session performing randomly the WI or control (CON, no water consumption) intervention at the end of the exercise. HR and RR intervals (RRi) were continuously recorded by a heart rate monitor before, during and after the exercise. Differences in HR recovery [e.g., absolute heart rate decrement after 1 min of recovery (HRR60s) and time-constant of the first order exponential fitting curve of the HRR (HRRτ)] and in postexercise vagal-related heart rate variability (HRV) indexes (rMSSD30s, rMSSD, pNN50, SD1 and HF) were calculated and compared for WI and CON. RESULTS A similar HR recovery and an increased postexercise HRV [SD1 = 9.4 ± 5.9 vs. 6.0 ± 3.9 millisecond, HF(ln) = 3.6 ± 1.4 vs. 2.4 ± 1.3 millisecond(2), for WI and CON, respectively; p < .05] was observed in WI compared with CON. CONCLUSION The results suggest that WI accelerates the postexercise parasympathetic reactivation after high-intensity exercise. Such outcome reveals an important cardioprotective effect of WI.

Post-exercise heart rate variability recovery: a time-frequency analysis

Objective Most studies investigating the eff ects of non-pharmacological interventions, such as physical training (PT), on cardiac autonomic control, assessed the HRV only in resting conditions. Recently, a new time-frequency mathematical approach based on the short-time Fourier transform (STFT) method has been validated for the assessment of HRV in non-stationary conditions such as the immediate post-exercise period. The aim of this study was to evaluate the eff ects of the PT on post-exercise cardiac autonomic control using the time-frequency STFT analysis of the HRV. Methods Twenty-one healthy male volunteers participated in this study. The subjects were initially evaluated for their physical exercise/sport practice and allocated to groups of low physical training (LowPT, n = 13) or high physical training (HighPT, n = 8). The post-exercise HRV was assessed by the STFT method, which provides the analysis of dynamic changes in the power of the low- and high-frequency spectral components (LF and HF, respectively) of the HRV during the whole recovery period. Results Greater LF (from the min 5 to 10) and HF (from the min 6 to 10) in the post-exercise period in the HighPT compared to the LowPT group (P < 0.05) was observed. Conclusion These results indicate that exercise training exerts benefi cial eff ects on post-exercise cardiac autonomic control.

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.

Yo-Yo IR2 test e teste de margaria: validade, confiabilidade e obtenção da frequência cardíaca máxima em jogadores jovens de futebol

The aims of the present study were: i) to evaluate the construct validity of Yo-Yo Intermittent Recovery Test Level 2 (Yo-Yo IR2) and of the Margaria Test (MT) with performance in high intensity exercise during official games in soccer players; ii) to verify the reliability (test-retest) of the two tests; iii) to compare the values of the maximal individual heart rate (MHR) obtained in those protocols and in game. Eighteen players (mean ± SD; age 14 ± 0.8 years, height 172 ± 9 cm, weight 64.3 ± 8.5 kg) belonging to the same team were assessed in test-retest referred protocols and in the percentage of time spent above 85% of MHR (PTS>85%MHR) in two official games of the U-15 Championship. High correlation was found between performance in the Yo-Yo IR2 and PTS>85%MHR (rs=0.71; p 85%MHR (rs=0.44; p=0.06). The Yo-Yo IR2 was more variable and less reproducible (CV= 11%; CCI [95% IC]=0.38) than MT (CV= 1%; CCI [95% IC]=0.93). The highest value of MHR (p<0.001) occurred in the game (202 ± 8 beats.min-1). MHR in Yo-Yo IR2 (194 ± 4 beats.min-1) was lower (p<0,006) than MT (197 ± 6 beats.min-1). In conclusion, the Yo-Yo IR2 can be considered more valid to predict maintenance of high exercise intensity during a match, which is an important performance measure in soccer. However, there is need of strict standardization among the evaluation procedures for stability of the measure. MHR should be observed in several situations, mainly competitive, so that the highest individual value can be reached.

Aerobic and Anaerobic Energy During Resistance Exercise at 80% 1RM

Aerobic and Anaerobic Energy During Resistance Exercise at 80% 1RM The present study investigated the accumulated oxygen deficit (AOD) method to assess the energy cost in resistance exercises (RE). The aim of the study was to evaluate the aerobic and anaerobic energy release during resistance exercises performed at 80% 1-RM in four exercises (half squat, bench press, triceps extension and lat pull down), as well as the accuracy of its estimation. The sample comprised 14 men (age = 26.6 ± 4.9 years; height = 177.7 ± 0.1 cm; body mass = 79.0 ± 11.1 kg; and estimated fat mass = 10.5 ± 4.6%). Test and re-test of 1-RM were applied to every exercise. Low-intensity bouts at 12, 16, 20, and 24% of 1-RM were conducted. Energy cost was then extrapolated to 80% 1-RM exhaustive bout and relative energy contribution were assessed. By utilizing the AOD method, the results of the present study suggest a great proportion of anaerobic metabolism during exercise at 80% 1-RM in the four RE that were analyzed: Bench press = 77,66±6,95%; Half squat = 87,44±6,45%; Triceps extension = 63,91±9,22%; Lat pull down = 71,99±13,73 %. The results of the present study suggest that AOD during resistance exercises presents a pattern that does not match the reports in the literature for other types of exercise. The accuracy of the total energy demand estimation at 80% 1-RM was acceptable in the Bench press, in the Triceps extension and in the Lat pull down, but no in the Half squat. More studies are warranted to investigate the validity of this method in resistance exercise.