The Effect of a Pace Training Session on Internal Load and Neuromuscular Parameters in Taekwondo Athletes.

This study aimed to verify the effect of a pace training session at an intensity corresponding to the kick frequency at the anaerobic threshold (KFAT) on the internal load response and motor response performance of the roundhouse kick. Twelve black belt taekwondo athletes underwent two evaluation sessions: (1) performed the progressive specific test for taekwondo (PSTT) to identify the heart rate deflection point (HRDP) and the KFAT; (2) performed three 2-min rounds with a 1-min interval. Heart rate (HR) throughout each round and motor response performance before and after sessions were measured. The Student's T-test or Wilcoxon test was used, and p < 0.05 was adopted. During round 1, a lower internal load was observed (167 ± 10 bpm) compared with HRDP (179 ± 8 bpm; p = 0.035). During rounds 2 (178 ± 10 bpm; p = 0.745) and 3 (179 ± 8 bpm; p = 1), no differences were observed for an internal load and HRDP. Motor response performance showed no differences. However, a potentiation in the post countermovement jump test compared with rounds 1 (p = 0.012) and 2 (p = 0.028) was observed. The internal load (HR) observed at the intensity corresponding to KFAT can be considered in the prescription of training when the aim is to control the internal load responses without inducing fatigue.

Pattern of the Heart Rate Performance Curve in Subjects with Beta-Blocker Treatment and Healthy Controls.

(1): Heart rate performance curve (HRPC) in incremental exercise was shown to be not uniform, causing false intensity estimation applying percentages of maximal heart rate (HRmax). HRPC variations are mediated by ß-adrenergic receptor sensitivity. The aim was to study age and sex dependent differences in HRPC patterns in adults with ß-blocker treatment (BB) and healthy controls (C). (2): A total of 535 (102 female) BB individuals were matched 1:1 for age and sex (male 59 ± 11 yrs, female 61 ± 11 yrs) in C. From the maximum incremental cycle ergometer exercise a first and second heart rate (HR) threshold (Th1 and Th2) was determined. Based on the degree of the deflection (kHR), HRPCs were categorized as regular (downward deflection (kHR > 0.1)) and non-regular (upward deflection (kHR < 0.1), linear time course). (3): Logistic regression analysis revealed a higher odds ratio to present a non-regular curve in BB compared to C (females showed three times higher odds). The odds for non-regular HRPC in BB versus C decreased with older age (OR interaction = 0.97, CI = 0.94-0.99). Maximal and submaximal performance and HR variables were significantly lower in BB (p < 0.05). %HRmax was significantly lower in BB versus C at Th2 (male: 77.2 ± 7.3% vs. 80.8 ± 5.0%; female: 79.2 ± 5.1% vs. 84.0 ± 4.3%). %Pmax at Th2 was similar in BB and C. (4): The HRPC pattern in incremental cycle ergometer exercise is different in individuals receiving ß-blocker treatment compared to healthy individuals. The effects were also dependent on age and sex. Relative HR values at Th2 varied substantially depending on treatment. Thus, the percentage of Pmax seems to be a stable and independent indicator for exercise intensity prescription.

Agreement between heart rate deflection point and maximal lactate steady state in young adults with different body masses.

We examined the agreement between heart rate deflection point (HRDP) variables with maximal lactate steady state (MLSS) in a sample of young males categorized to different body mass statuses using body mass index (BMI) cut-off points. One hundred and eighteen young males (19.9 ± 4.4 years) underwent a standard running incremental protocol with individualized speed increment between 0.3 and 1.0 km/h for HRDP determination. HRDP was determined using the modified Dmax method called S.Dmax. MLSS was determined using 2-5 series of constant-speed treadmill runs. Heart rate (HR) and blood lactate concentration (La) were measured in all tests. MLSS was defined as the maximal running speed yielding a La increase of less than 1 mmol/L during the last 20 min. Good agreement was observed between HRDP and MLSS for HR for all participants (±1.96; 95% CI = -11.5 to +9.2 b/min, ICC = 0.88; P < 0.001). Good agreement was observed between HRDP and MLSS for speed for all participants (±1.96; 95% CI = -0.40 to +0.42 km/h, ICC = 0.98; P < 0.001). The same findings were observed when participants were categorized in different body mass groups. In conclusion, HRDP can be used as a simple, non-invasive and time-efficient method to objectively determine submaximal aerobic performance in nonathletic young adult men with varying body mass status, according to the chosen standards for HRDP determination.

[The relationship between heart rate inflection point and lactate recovery and lung function in healthy adults at the Plateau].

Objective: To explore the relationship between heart rate deflection point (HRDP) and blood lactate recovery ability and lung function of healthy people aged 20～40 years old in a plateau environment of 3 200 m. Methods: 225 healthy people aged 20～40 who lived on a plateau of 3 200 m were used as the research subjects. The HRDP strength, heart rate recovery ability and blood lactate recovery ability were evaluated by the changes of heart rate and blood lactate recovery before, during and after the modified Conconi test. Results: ①The heart rate of the subjects increased with the increase in exercise intensity, and the heart rate of the recovery period after exercise showed a downward trend, the rate of Conconi test center was significantly lower in male than that in female(P＜ 0.05). At the same age, male HRDP appeared later, and female HRDP appeared earlier. At the same sex stage, the time of HRDP appeared earlier in the male group with increasing age, while the phenomenon in the female group was not significant. HRDP speed had a downward trend with age. ②The inflection point concentration of blood lactic acid in the subjects gradually decreased with age, but there was no significant difference between the low-age group and the high-age group; the blood lactic acid level in the Conconi test of healthy adult males living on the plateau was significantly lower than that of females(P＜0.05). ③FVC, MVV, FEV1 and FEV1/FVC levels in each gender group showed a downward trend with age, and the data of the male group and above were significantly higher than the female group of the same age (P＜0.05). ④Load-Heart Rate curve and Heart Rate-Blood Lactate fitting curve showed that the correlation coefficients of the male group were 0.8345, 0.8954, 0.8680, and 0.8892 in sequence; the correlation coefficients of the female group were in sequence 0.9318, 0.9661, 0.9663 and 0.9599. HRDP values of all genders and age groups were significantly correlated with their MVV levels (P＜0.05). Except for subjects 36～40 years old in the male group, lung function and lactate elimination rate of all genders and age groups were also significantly correlated (P＜0.05). Conclusion: There are age and gender differences in exercise heart rate response rules and respiratory system functions of healthy people aged 20～40 years old living on 3 200 m plateau. There is a significant correlation between HRDP and lactic acid recovery capacity and lung function. The above indicators can be used to assess the aerobic exercise endurance ability of healthy adults living on plateau.

Heart rate deflection point as an alternative to determining the anaerobic threshold in dyslipidaemic patients

Aim: The aim of the present study was to verify the agreement between the ventilatory method (VT) and the alternative method of heart rate deflection point (HRDP) in determining the anaerobic threshold (AT) during incremental treadmill test in dyslipidaemic patients. Methods: Twenty-seven dyslipidaemic patients (61.50 ± 10.46 years) performed an incremental treadmill test, in which the AT was determined using both methods. Bland-Altman statistics was adopted in order to verify the agreement between the methods. Results: Agreement in AT determination between the VT and HRDP methods was observed (p < 0.05) for heart rate (138.00 ± 23.80 and 136.26 ± 22.18 bpm, respectively), oxygen uptake (31.00 ± 10.33 and 31.00 ± 11.17 ml.kg−1.min−1), and treadmill velocity (7.67 ± 1.71 km.h-1and 8.00 ± 1.75 km.h-1). Conclusion: Our results suggest that the HRDP method can be adopted for the determination of the AT in dyslipidaemic patients, showing agreement with the VT method.(AU)

Prediction of lactate threshold using the modified Conconi test in distance runners.

This study aimed to examine the validity of the modified Conconi test (CT) to predict lactate threshold (LT) during running. Twelve distance runners randomly performed the modified CT and the incremental test in which LT was determined directly by measuring blood lactate (BLa). Mean values of heart rate (HR) and running speed (RS) at heart rate deflection point (HRDP) obtained through the modified CT were compared with those at LT. Subsequently, the runners who showed a HRDP in the modified CT performed a 30-min prolonged exercise test (PET) at a RS corresponding to HRDP. During this test, the kinetics of BLa and HR were analyzed to determine whether a steady state in these variables could be attained. We succeeded in identifying HRDP in nine of our runners, whereas the remaining three runners showed entirely linear HR response. In those nine runners, no significant difference was found between HR and RS at HRDP and those at LT. Significant correlation was found between HR at HRDP and HR at LT (r = 0.84, p = 0.005), but RS at HRDP was not significantly correlated with RS at LT (r = 0.63, p = 0.07). All nine runners were able to complete the PET with steady state conditions being achieved for both BLa and HR. In conclusion, these findings indicate that the modified CT has a potential to be used as an alternative method for assessment of LT in distance runners presenting a HRDP.