A preliminary systematic review and meta-analysis on the effects of heart rate variability biofeedback on heart rate variability and respiration of athletes.

To date, there is no quantitative review examining the influence of heart rate variability biofeedback (HRV BFB) on the athlete population. Such an undertaking may provide valuable information on the autonomic and respiration responses of athletes when performing HRV BFB. Thus, purpose of this preliminary systematic review and meta-analysis on the effects of HRV BFB on HRV and respiration of athletes. Searches of Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect were conducted for studies that met the following criteria: (1) experimental studies involving athletes that underwent randomized control trial; (2) availability of HRV BFB as a treatment compared with a control (CON)/placebo (PLA); (3) any pre and post HRV variable and/or breathing frequency as dependent variable/s; and, (4) peer-reviewed articles written in English. Four out of 660 studies involving 115 athletes (25 females and 90 males) ages 16-30 years old were assessed in this review. Preliminary findings suggest the promising ability of HRV BFB to improve respiratory mechanics in athlete population. More work is needed to determine the autonomic modulatory effect of HRV BFB in athletes.

Effect of Acute Heart Rate Variability Biofeedback on H-reflex Modulation: A Pilot Study.

Heart rate variability biofeedback (HRV BFB) is paced breathing scheme that stimulates resonance in the cardiovascular system. This study aimed to investigate the effect of a single-session HRV BFB on Hoffman reflex (H-reflex) of the soleus muscle. Twelve healthy males (height: 173.7 ± 7.18 cm; weight: 72.7 ± 17.7 kg; age: 24.0 ± 5.02 yrs) completed a randomized-crossover intervention involving a 10-minute HRV BFB and normal breathing (CON) separated by 48 hours. Results revealed significantly lower 1a afferent activation after HRV BFB. Similarly, the HRV BFB also demonstrated lower proportion of activated motor neurons from 1a afferents. In conclusion, an acute HRV BFB influenced the reduction in motoneuron excitability at resting condition.

Can Heart Rate Variability Biofeedback Improve Athletic Performance? A Systematic Review.

This systematic review was conducted to evaluate the effect of heart rate variability biofeedback (HRV BFB) on performance of athletes. Six electronic databases (Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect) and article references were searched. Eligibility criteria were: 1. experimental studies involving athletes randomly allocated among groups (randomized control trial); 2. availability of HRV BFB as a treatment compared to a control condition (CON) that involves regular sport/dance training, a placebo (PLA) or other methods of BFB; 3. performance-related variables such as a dependent index; and, 4. peer-reviewed articles written in English. Out of 660 articles, six studies were included in the systematic review which involved 187 athletes (females: n = 89; males n = 98). Six studies compared HRV BFB with a CON, three studies compared HRV BFB with a PLA, and two studies differentiated HRV BFB with other methods of BFB. Findings support HRV BFB as a potential intervention to improve fine and gross motor function in athletes.

Acquired and Genetic Thrombotic Risk Factors in the Athlete.

While athletes are often considered the epitome of health due to their physique and lowered potential for metabolic and cardiovascular diseases, they may also be at risk for the onset and development of venous thromboembolism (VTE). In an attempt to achieve and remain competitive, athletes are frequently exposed to numerous athlete-specific risk factors, which may predispose them to VTE through the disruption of factors associated with Virchow's triad (i.e., hypercoagulability, venous stasis, and vessel wall injury). Indeed, hypercoagulability within an athletic population has been well documented to occur due to a combination of multiple factors including exercise, dehydration, and polycythemia. Furthermore, venous stasis within an athletic population may occur as a direct result of prolonged periods of immobilization experienced when undertaking long-distance travels for training and competition, recovery from injury, and overdevelopment of musculature. While all components of Virchow's triad are disrupted, injury to the vessel wall has emerged as the most important factor contributing to thrombosis formation within an athletic population, due to its ability to influence multiple hemostatic mechanisms. Vessel wall injury within an athletic population is often related to repetitive microtrauma to the venous and arterial walls as a direct result of sport-dependent trauma, in addition to high metabolic rates and repetitive blood monitoring. Although disturbances to Virchow's triad may not be detrimental to most individuals, approximately 1 in 1,000 athletes will experience a potentially fatal post-exercise thrombotic incidence. When acquired factors are considered in conjunction with genetic predispositions to hypercoagulability present in some athletes, an overall increased risk for VTE is present.

Time of day and short-duration high-intensity exercise influences on coagulation and fibrinolysis.

Exercise has been demonstrated to have considerable effects upon haemostasis, with activation dependent upon the duration and intensity of the exercise bout. In addition, markers of coagulation and fibrinolysis have been shown to possess circadian rhythms, peaking within the morning (0600-1200 h). Therefore, the time of day in which exercise is performed may influence the activation of the coagulation and fibrinolytic systems. This study aimed to examine coagulation and fibrinolytic responses to short-duration high-intensity exercise when completed at different times of the day. Fifteen male cyclists (VO2max: 60.3 ± 8.1 ml kg-1 min-1) completed a 4-km cycling time trial (TT) on five separate occasions at 0830, 1130, 1430, 1730 and 2030. Venous blood samples were obtained pre- and immediately post-exercise, and analysed for tissue factor (TF), tissue factor pathway inhibitor (TFPI), thrombin-anti-thrombin complexes (TAT) and D-Dimer. Exercise significantly increased plasma concentrations of TF (p < .0005), TFPI (p < .0006), TAT complexes (p < .0012) and D-Dimer (p < .0003). There was a time-of-day effect in pre-exercise TF (p = .004) and TFPI (p = .031), with 0830 greater than 1730 (p .001), while 1730 was less than 2030 h (p = .008), respectively. There was no significant effect of time of day for TAT (p = .364) and D-Dimer (p = .228). Power output, TT time and heart rate were not significantly different between TTs (p > .05); however, percentage VO2max was greater at 1730 when compared to 2030 (p = .04). Due to a time-of-day effect present within TF, peaking at 0830, caution should be applied when prescribing short-duration high-intensity exercise bout within the morning in populations predisposed to hypercoagulability.

Confounding compression: the effects of posture, sizing and garment type on measured interface pressure in sports compression clothing.

The purpose of this investigation was to measure the interface pressure exerted by lower body sports compression garments, in order to assess the effect of garment type, size and posture in athletes. Twelve national-level boxers were fitted with sports compression garments (tights and leggings), each in three different sizes (undersized, recommended size and oversized). Interface pressure was assessed across six landmarks on the lower limb (ranging from medial malleolus to upper thigh) as athletes assumed sitting, standing and supine postures. Sports compression leggings exerted a significantly higher mean pressure than sports compression tights (P < 0.001). Oversized tights applied significantly less pressure than manufacturer-recommended size or undersized tights (P < 0.001), yet no significant differences were apparent between different-sized leggings. Standing posture resulted in significantly higher mean pressure application than a seated posture for both tights and leggings (P < 0.001 and P = 0.002, respectively). Pressure was different across landmarks, with analyses revealing a pressure profile that was neither strictly graduated nor progressive in nature. The pressure applied by sports compression garments is significantly affected by garment type, size and posture assumed by the wearer.