Heart Rate Variability: a Follow-up in Elite Soccer Players Throughout the Season.

Heart rate variability (HRV) can provide useful information on physiological adaptations to training, but its role is unknown in professional soccer. The aim of this study was to determine an HRV profile in professional soccer over a season. A total of 504 records were made of the heart beat signal throughout a season from 22 professional soccer players. HRV was recorded in a sitting position, early morning and fasting for a period of 10 min. Standard deviation 1 and 2 (SD1, SD2), standard deviation of normal to normal R-R intervals (SDNN), Root Mean Square of the Successive Differences (rMSSD), percentage of RR intervals > 50 ms (pNN50), Sample Entropy (SampEn), Stress Score (SS) and sympathetic/parasympathetic ratio (S/PS ratio) were calculated. SDNN, rMSSD, pNN50, SD1 and SD2 showed an identical behaviour throughout the season, with lower values in the pre-season and the end of the season. SS and S/PS ratio indicated a sympathetic stress alert in the same periods. A weekly recording of the HRV over a 10 min period that includes a Poincaré plot with SS and S/PS ratio and at least one variable of the time domain is a useful tool for the follow-up of the individual assimilation of weekly workloads, including the game.

Effects of eccentric overload bout on change of direction and performance in soccer players.

The aims of this study were to analyse the effects of eccentric overload training (EOT) on kinetic parameters during change of direction (COD) and performance related to sprinting and jumping abilities. 20 male soccer players performed 2 different protocols: 1) 5-min cycling warm-up and 2) 5-min cycling warm-up+YoYo half-squat exercise. The outcome measured included vertical ground reaction force (vGRF) and propulsive force (PvGRF), time to vGRF (T_vGRF) and propulsive force (T_PvGRF), contact time (CT), eccentric (ECC_IMP), concentric (CONC_IMP) and total (TOT_IMP) impulses and moments (Mx, My and Mz) during 2 COD tasks. Additionally, subjects performed a counter-movement jump (CMJ) and 20 m sprint tests. Results showed a substantial better improvement (likely to almost certainly) in vGRF (ES: 0.84), vAGRF (ES: 0.72), CT (ES: 0.48), My (ES: 0.35), Mz (ES: 0.44) and ECC_IMP (ES: 0.45) during crossover cutting maneuver, whereas during side-step cutting maneuver Time_ECC (ES: 0.68), CT (ES: 0.64), vGRF (ES: 0.48) and My (ES: 0.47) were substantially enhanced (likely). Furthermore, substantial better performance was found in CMJ (ES: 0.47; very likely) and 20 m (ES: 0.20; possibly). In conclusion, EOT produced a better muscle activation during 2 different COD tasks and greater sprinting and jumping performance.

Cardiac autonomic response during recovery from a maximal exercise using whole body vibration.

OBJECTIVE: To examine the effect of passive whole-body vibration (WBV) on heart rate (HR) variability (HRV) during the recovery from intense exercise. DESIGN: Randomized, counterbalanced, crossover design SETTING: Laboratory. INTERVENTIONS: Twenty-three healthy male performed a bicycle exercise test to exhaustion followed by an active recovery period using WBV (25Hz and peak to peak displacement of 4mm) or passive recovery period (noWBV; 0Hz-0mm) on two separate days in random order. The recovery protocol consisted of six 1-min sets separated by 1-min inter-set rest periods in the seated position with the feet on the vibration platform. ECG recordings were made at baseline and during recovery at min 2, 4, 6, 8, 10 and 12 in both conditions. Frequency-domain measures of HRV were determined via power spectral analysis using fast-Fourier transform. Low frequency (LF; 0.04-0.15Hz) and high frequency bandwidths (HF; 0.15-0.4Hz) were determined. RESULTS: HR was increased in both groups (P<0.01) throughout the recovery. At min 2, HR was lower (P=0.05) after WVB compared to the noWBV trial. At min 3, the increase (P<0.05) in total power after WBV was significantly different (P<0.01) compared to noWBV. Normalized (nu) LF and LF/HF were increased (P<0.01), whereas HF nu was reduced (P<0.001) in both conditions without a significant group-by-time interaction (P=0.08). CONCLUSION: Passive WBV reduces HR and increases total power during the early recovery of intense exercise, despite no effect on power spectral components of HRV.

The effect of 6-week exercise programme and whole body vibration on strength and quality of life in women with fibromyalgia: a randomised study.

OBJECTIVES: The aim of this study was to investigate the effectiveness of a 6-week traditional exercise programme with supplementary whole-body vibration (WBV) in improving strength and health status in women with fibromyalgia (FM). METHODS: Thirty postmenopausal women with FM (mean (SD) age: 59 (7.90) years) were randomised into one of two groups, one intervention group (GEV n=15), which combined exercise training (two days a week) with three days of WBV (3 sets of 45 s at 20 Hz-3 mm and four sets of unilateral static squats at 20 Hz-2 mm) and another control group (n=15), that performed the same physical activity programme but without vibration training (GEnV). The Fibromyalgia Impact Questionnaire (FIQ) and the global score of the SF-36 were used to assess functional capacity and quality of life. Two additional tests were employed to assess muscle strength. Baseline data and pre-test and post-test data were collected before and after the six-week intervention period. RESULTS: Significant improvements in all outcomes measured were found from baseline in both groups. A 5% improvement from baseline in total FIQ score was observed in the exercise groups (p≤0.05), and was accompanied by reductions in SF36 scores of 9.8% (p<0.001) and 7.9% (p<0.001) in the GEV and GEnV group, respectively. Improvements were also observed in muscle strength in both groups but greater in the GEV group. CONCLUSIONS: The results suggest that women with FMS can gain additional health benefits by engaging in a 6-week traditional exercise programme with supplementary WBV.