Age-related maximal heart rate: examination and refinement of prediction equations.

AIM: The aim of this study was to establish the maximal heart rate (HRmax)-age relation with minimal error rate. METHODS: The records of 28,137 participants (20,691 male and 7446 female, age range between 10 and 80 yrs) who performed a maximal stress test were used in this study. Linear regressions between HRmax and age were used for the entire sample, for the male and female samples, separately, and for each section of the gender-by-age category. The equations were then contrasted to a number of equations reported in the literature. The best fitted equations were then tested on a new sample of 2449 subjects (2091 males and 358 females) for validation purposes. RESULTS: Mean HRmax values were found to decrease at a faster rate in women than in men with age increase. The linear regression functions within each age category were found to be less reliable than the equations derived for the entire sample and for the female and male samples, respectively. The new and updated HRmax prediction equations are as follows: HRmax=208.609-0.716age and 209.273-0.804age for males and females, respectively, and 208.852-0.741age for the entire sample. Those equations along with the other four best equations for predicting HRmax were found to be correlated with the observed HRmax values (validation sample): 0.64 and 0.664 for males and females, respectively. CONCLUSION: Our equations were derived from a large data set and were found to be highly sensitive for both genders. Therefore, we propose that these new formulas, with their improved accuracy, be used in healthy active and clinical populations.

Heart rate monitoring as a reliable tool for assessing energy expenditure in obese individuals.

Previous studies have suggested the use of the FlexHR method for predicting daily energy expenditure in various populations. We investigated the stability of the relation between oxygen consumption (VO2) and heart rate (HR) in obese subjects undergoing a fitness and weight reduction program. Eleven obese (BMI>30) healthy subjects (6 males, 5 females) were recruited from a Wellness program. Subjects performed a laboratory calibration procedure between HR and VO2 in resting and exercising conditions, before starting the Wellness program (Stage I) and after reducing 10% of their initial body weights (BW) within 6 months (Stage II). Mean BW, BMI and % body fat were reduced by 13.1±4.4 kg, 4.2±1.4 kg.m-2 and 6.8±4.1%, respectively, for all parameters (P<0.001). Mean peak VO2 increased from 31.3±7.1 at the beginning to 37.2±7.3 mL.kg-1.min-1 at the end of the intervention period (P<0.01). The mean flex HR point changed from 96±14 to 86±15 beats.min-1 (P<0.05). There were no significant individual differences in the HR-VO2 prediction equations derived from the laboratory calibrations in either stage. In conclusion, the relationship between HR and VO2 consumption remains stable during a time period of weight reduction. The use of the FlexHR method for predicting energy expenditure by heart rate monitoring is recommended for subjects undergoing a weight-reduction program. It should be taken in account, however, that an increase in aerobic capacity, in parallel to changes in body weight and composition, might cause a decrease in the flex point.

Hormonal response to Taekwondo fighting simulation in elite adolescent athletes.

Exercise training efficiency depends on the training load, as well as on the athlete's ability to tolerate it. The aim of the present study was to evaluate the effect of fighting simulation (3 fights, 6 min each, 30 min rest between fights) on anabolic (IGF-I, LH, FSH, estradiol, and testosterone) and catabolic hormones (cortisol) in elite, male (n = 10) and female (n = 10) adolescent (12-17 years) Taekwondo fighters. Blood samples were collected before the first and immediately after the third fight. The fighting simulation practice led to significant (p < 0.05) decreases in IGF-I (males -27.1 ± 25.6, females -22.4 ± 36.3 ng/ml), LH (males -0.7 ± 1.2, females -2.3 ± 3.3 U/L), and FSH (males -0.9 ± 0.5, females -1.5 ± 1.1 U/L), and to a significant increase (p < 0.05) in cortisol (males 141.9 ± 30.1, females 64.1 ± 30.6 mcg/dL) in both genders. Fighting simulation decreases in testosterone (males -1.9 ± 1.6, females -0.02 ± 0.06 ng/mL), and free androgen index (males -20.1 ± 21.5, females -0.3 ± 0.5) were significant (p < 0.05) only in male fighters. Exercise had no significant effect on estradiol, sex-hormone-binding globulins or thyroid function tests. Our data demonstrate that the physiologic and psychologic strain of a Taekwondo fighting simulation day led to a catabolic-type circulating hormonal response.