Estimation of maximal heart rate in recreational football: a field study

Temporal patterns of fatigue in repeated sprint ability testing in soccer players and acute effects of different IHRs: a comparison between genders

BACKGROUND

Repeated sprint ability (RSA) in soccer is deemed fundamental to ensure high level of performance. The aim of this study was to investigate the acute effects of two different Initial Heart Rates (IHR) on fatigue when testing RSA in males and females' soccer players and to compare the respective patterns of fatigue.

METHODS

Nineteen female soccer players (age: 22.5±3.3 years, height 163.9±7.3 cm, body weight 54.3±6.4 kg, BMI 20.6±1.5 kg·m^-2) and 15 male soccer players (age: 17.9±1.5 years, height 175.9±5.8 cm, body weight 68.5±9.6 kg, BMI 22.3±1.5 kg·m^-2) participated in this study. HRs reached at the end of two different warm-up protocols (~90 vs. ~ 60% HR<inf>max</inf>), have been selected and the respective RSA performances were compared, within and between the groups of participants. Two sets of ten shuttle-sprints (15+15 m) with a 1:3 exercise to rest ratio with different IHR% were administered, in different days, in randomized order. To compare the different sprint performances, we employed the calculated Fatigue Index (FI%). Blood lactate concentration (BLa^-) was also measured before and after testing, to compare metabolic energy.

RESULTS

Significant differences among trials within each set (P<0.01) were found in both genders. Differences between sets were found in male players, (Factorial ANOVA 2x5; P<0.001), not in female. BLa^- after warm-up was higher in 90% vs. 60% HR<inf>max</inf> (P<0.05), in both genders but at the completion of RSA tests (after 3 minutes) the differences were not significant (P>0.05).

CONCLUSIONS

difference between genders were found, suggesting specific approach in testing and training RSA in soccer players.

Estimation of maximal oxygen uptake using the heart rate ratio method in male recreational football players

Maximal oxygen uptake (VO_2max) is associated with cardiovascular and metabolic health in the general population. The heart rate (HR) ratio method (HR_ratio) is a valid, easy and accessible method for estimating VO_2max in well-trained subjects. This study examined the validity of using the HR_ratio to estimate VO_2max in recreational football players in the untrained and trained states. Sixty-six participants (age 39.3 ± 5.8 years) were tested pre-training and 28 after 12 weeks, for VO_2max assessment, running on a treadmill alternating speed (1 km h⁻¹) and inclination (1%) increments every 30 s until exhaustion. Maximal HR (HR_max) was assessed directly with a multiple approach and estimated with selected equations. Resting HR (HR_rest) was measured in supine position, after 15 min of rest. The HR_ratio method considers the product of HR_max/HR_rest ratio by a theoretical proportionality factor (15 ml kg⁻¹ min⁻¹, TPF) to estimate VO_2max. This population-specific proportionality factor (SPF) was 14.6 ± 2.6 ml kg⁻¹ min⁻¹. In the untrained state (n = 66), participants’ actual VO_2max (41.3 ± 6.2 ml kg⁻¹ min⁻¹) was moderately lower (~ 2 ml kg⁻¹ min⁻¹) than the estimated VO_2max using the TPF. A nonsignificant difference (0.7 ml kg⁻¹ min⁻¹) was found when the VO_2max was estimated using the SPF. When using HR_max equations and the TPF, a small nonsignificant difference (~ 1.5 ml kg⁻¹ min⁻¹) was reported between actual and estimated VO_2max. In the trained state (n = 28), the estimated VO_2max values were not significantly different from the actual VO_2max (44.2 ± 5.2 ml kg⁻¹ min⁻¹), with large effect sizes when considering TPF and estimated HR_max. The results of this study provide evidence of the applicability of HR_ratio in estimating VO_2max in male adult/middle-aged recreational football players.