@article{RogersGilesDraperetal.2021,
  author    = {Rogers, Bruce and Giles, David and Draper, Nick and Hoos, Olaf and Gronwald, Thomas},
  title     = {A New Detection Method Defining the Aerobic Threshold for Endurance Exercise and Training Prescription Based on Fractal Correlation Properties of Heart Rate Variability},
  series = {Frontiers in Physiology},
  volume    = {11},
  journal   = {Frontiers in Physiology},
  issn      = {1664-042X},
  doi       = {10.3389/fphys.2020.596567},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-222601},
  year      = {2021},
  abstract  = {The short-term scaling exponent alpha1 of detrended fluctuation analysis (DFA a1), a nonlinear index of heart rate variability (HRV) based on fractal correlation properties, has been shown to steadily change with increasing exercise intensity. To date, no study has specifically examined using the behavior of this index as a method for defining a low intensity exercise zone. The aim of this report is to compare both oxygen intake (VO\(_{2}\)) and heart rate (HR) reached at the first ventilatory threshold (VT1), a well-established delimiter of low intensity exercise, to those derived from a predefined DFA a1 transitional value. Gas exchange and HRV data were obtained from 15 participants during an incremental treadmill run. Comparison of both VO\(_{2}\) and HR reached at VT1 defined by gas exchange (VT1 GAS) was made to those parameters derived from analysis of DFA a1 reaching a value of 0.75 (HRVT). Based on Bland Altman analysis, linear regression, intraclass correlation (ICC) and t testing, there was strong agreement between VT1 GAS and HRVT as measured by both HR and VO\(_{2}\). Mean VT1 GAS was reached at 39.8 ml/kg/min with a HR of 152 bpm compared to mean HRVT which was reached at 40.1 ml/kg/min with a HR of 154 bpm. Strong linear relationships were seen between test modalities, with Pearson's r values of 0.99 (p < 0.001) and.97 (p < 0.001) for VO\(_{2}\) and HR comparisons, respectively. Intraclass correlation between VT1 GAS and HRVT was 0.99 for VO\(_{2}\) and 0.96 for HR. In addition, comparison of VT1 GAS and HRVT showed no differences by t testing, also supporting the method validity. In conclusion, it appears that reaching a DFA a1 value of 0.75 on an incremental treadmill test is closely associated with crossing the first ventilatory threshold. As training intensity below the first ventilatory threshold is felt to have great importance for endurance sport, utilization of DFA a1 activity may provide guidance for a valid low training zone.},
  language  = {en}
}
@article{GronwaldRogersHoos2020,
  author    = {Gronwald, Thomas and Rogers, Bruce and Hoos, Olaf},
  title     = {Fractal Correlation Properties of Heart Rate Variability: A New Biomarker for Intensity Distribution in Endurance Exercise and Training Prescription?},
  series = {Frontiers in Physiology},
  volume    = {11},
  journal   = {Frontiers in Physiology},
  issn      = {1664-042X},
  doi       = {10.3389/fphys.2020.550572},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212429},
  year      = {2020},
  abstract  = {Exercise and training prescription in endurance-type sports has a strong theoretical background with various practical applications based on threshold concepts. Given the challenges and pitfalls of determining individual training zones on the basis of subsystem indicators (e.g., blood lactate concentration, respiratory parameters), the question arises whether there are alternatives for intensity distribution demarcation. Considering that training in a low intensity zone substantially contributes to the performance outcome of endurance athletes and exceeding intensity targets based on a misleading aerobic threshold can lead to negative performance and recovery effects, it would be desirable to find a parameter that could be derived via non-invasive, low cost and commonly available wearable devices. In this regard, analytics conducted from non-linear dynamics of heart rate variability (HRV) have been adapted to gain further insights into the complex cardiovascular regulation during endurance-type exercise. Considering the reciprocal antagonistic behavior and the interaction of the sympathetic and parasympathetic branch of the autonomic nervous system from low to high exercise intensities, it may be promising to use an approach that utilizes information about the regulation quality of the organismic system to determine training-intensity distribution. Detrended fluctuation analysis of HRV and its short-term scaling exponent alpha1 (DFA-alpha1) seems suitable for applied sport-specific settings including exercise from low to high intensities. DFA-alpha1 may be taken as an indicator for exercise prescription and intensity distribution monitoring in endurance-type sports. The present perspective illustrates the potential of DFA-alpha1 for diagnostic and monitoring purposes as a "global" system parameter and proxy for organismic demands.},
  language  = {en}
}
@article{DuekingZinnerReedetal.2020,
  author    = {D{\"u}king, Peter and Zinner, Christoph and Reed, Jennifer L. and Holmberg, Hans-Christer and Sperlich, Billy},
  title     = {Predefined vs data-guided training prescription based on autonomic nervous system variation: A systematic review},
  series = {Scandinavian Journal of Medicine \& Science in Sports},
  volume    = {30},
  journal   = {Scandinavian Journal of Medicine \& Science in Sports},
  number    = {12},
  doi       = {10.1111/sms.13802},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217893},
  pages     = {2291 -- 2304},
  year      = {2020},
  abstract  = {Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake (VO\(_{2peak}\)) and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in VO\(_{2peak}\). Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.},
  language  = {en}
}
@article{GronwaldHoos2020,
  author    = {Gronwald, Thomas and Hoos, Olaf},
  title     = {Correlation properties of heart rate variability during endurance exercise: A systematic review},
  series = {Annals of Noninvasive Electrocardiology},
  volume    = {25},
  journal   = {Annals of Noninvasive Electrocardiology},
  number    = {1},
  doi       = {10.1111/anec.12697},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213548},
  year      = {2020},
  abstract  = {Background Non-linear measures of heart rate variability (HRV) may provide new opportunities to monitor cardiac autonomic regulation during exercise. In healthy individuals, the HRV signal is mainly composed of quasi-periodic oscillations, but it also possesses random fluctuations and so-called fractal structures. One widely applied approach to investigate fractal correlation properties of heart rate (HR) time series is the detrended fluctuation analysis (DFA). DFA is a non-linear method to quantify the fractal scale and the degree of correlation of a time series. Regarding the HRV analysis, it should be noted that the short-term scaling exponent alpha1 of DFA has been used not only to assess cardiovascular risk but also to assess prognosis and predict mortality in clinical settings. It has also been proven to be useful for application in exercise settings including higher exercise intensities, non-stationary data segments, and relatively short recording times. Method Therefore, the purpose of this systematic review was to analyze studies that investigated the effects of acute dynamic endurance exercise on DFA-alpha1 as a proxy of correlation properties in the HR time series. Results The initial search identified 442 articles (351 in PubMed, 91 in Scopus), of which 11 met all inclusion criteria. Conclusions The included studies show that DFA-alpha1 of HRV is suitable for distinguishing between different organismic demands during endurance exercise and may prove helpful to monitor responses to different exercise intensities, movement frequencies, and exercise durations. Additionally, non-linear DFA of HRV is a suitable analytical approach, providing a differentiated and qualitative view of exercise physiology.},
  language  = {en}
}
@article{ReichelMitnachtFenwicketal.2019,
  author    = {Reichel, Thomas and Mitnacht, Martin and Fenwick, Annabel and Meffert, Rainer and Hoos, Olaf and Fehske, Kai},
  title     = {Incidence and characteristics of acute andoveruse injuries in elite powerlifters},
  series = {Cogent Medicine},
  volume    = {6},
  journal   = {Cogent Medicine},
  doi       = {10.1080/2331205X.2019.1588192},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204005},
  pages     = {1588192},
  year      = {2019},
  abstract  = {Abstract: The aim of this study was the analysis of incidence and type of injury in German elite powerlifters. A total of n = 57 competitive athletes of the German powerlifting federation completed a retrospective survey regarding acute andoveruse injuries. With 224 total injuries, a mean incidence of 1.51 per 1.000 h or 0.49 per year was calculated. Most injuries affected the lower back (20.5\%), elbow (11.2\%), pelvic region (10.3) and the shoulder (9.8\%). Regarding the type of injury acute inflammation (25.9\%), muscle strains/sprains (20.5\%) and skin lesions (13\%) dominated. The mean incidence significantly declined with increasing age and training experience of the athlete. Athletes using a bench press shirt and various regenerative methods like sauna or swimming also showed decreased injury rates. There was no significant correlation between body weight, height or gender and injury incidence. Compared to other sports, the incidence of injuries and overuse syndromes is still low in powerlifting. Nonetheless, appropriate strategies in training, equipment, prevention and regeneration should be employed to protect the athlete from injury.},
  language  = {en}
}