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Haarlem CS, O’Connell RG, Mitchell KJ, Jackson AL. The speed of sight: Individual variation in critical flicker fusion thresholds. PLoS One 2024; 19:e0298007. [PMID: 38557652 PMCID: PMC10984398 DOI: 10.1371/journal.pone.0298007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 01/16/2024] [Indexed: 04/04/2024] Open
Abstract
The critical flicker fusion threshold is a psychophysical measure commonly used to quantify visual temporal resolution; the fastest rate at which a visual system can discriminate visual signals. Critical flicker fusion thresholds vary substantially among species, reflecting different ecological niches and demands. However, it is unclear how much variation exists in flicker fusion thresholds between healthy individuals of the same species, or how stable this attribute is over time within individuals. In this study, we assessed both inter- and intra-individual variation in critical flicker fusion thresholds in a cohort of healthy human participants within a specific age range, using two common psychophysical methods and three different measurements during each session. The resulting thresholds for each method were highly correlated. We found a between-participant maximum difference of roughly 30 Hz in flicker fusion thresholds and we estimated a 95% prediction interval of 21 Hz. We used random-effects models to compare between- and within-participant variance and found that approximately 80% of variance was due to between-individual differences, and about 10% of the variance originated from within-individual differences over three sessions. Within-individual thresholds did not differ significantly between the three sessions in males, but did in females (P<0.001 for two methods and P<0.05 for one method), indicating that critical flicker fusion thresholds may be more variable in females than in males.
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Affiliation(s)
- Clinton S. Haarlem
- Department of Zoology, Trinity College Dublin, Dublin, Ireland
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Redmond G. O’Connell
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
| | - Kevin J. Mitchell
- Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
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Wendi W, Dongzhe W, Hao W, Yongjin S, Xiaolin G. Effect of dry dynamic apnea on aerobic power in elite rugby athletes: a warm-up method. Front Physiol 2024; 14:1269656. [PMID: 38292448 PMCID: PMC10824898 DOI: 10.3389/fphys.2023.1269656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 12/28/2023] [Indexed: 02/01/2024] Open
Abstract
Objective: While long-term dynamic breath-holding training has been extensively studied to enhance cardiopulmonary function in athletes, limited research has explored the impact of a single breath-holding session on subsequent athletic capacity. In addition, Dry Dynamic Apnea (DA) has a more immediate physiological response than wet and static breath-holding. This study aims to assess the immediate effects of a single session of DA on the aerobic power and hematological parameters of elite athletes. Methods: Seventeen elite male rugby athletes (average age 23.5 ± 1.8) participated in this study. Two warm-up protocols were employed prior to incremental exercise: a standard warm-up (10 min of no-load pedaling) and a DA warm-up (10 min of no-load pedaling accompanied by six maximum capacity breath holds, with 30 s between each breath hold). Fingertip blood indicators were measured before and after warm-up. The incremental exercise test assessed aerobic parameters with self-regulation applied throughout the study. Results: Compared to the baseline warm-up, the DA warm-up resulted in a significant increase in VO2peak from 3.14 to 3.38 L/min (7.64% change, p < 0.05). HRmax increased from 170 to 183 bpm (7.34% change, p < 0.05), and HRpeak increased from 169 to 182 bpm (7.52% change, p < 0.05). Hematocrit and hemoglobin showed differential changes between the two warm-up methods (PHematocrit = 0.674; Phemoglobin = 0.707). Conclusion: This study investigates how DA influences physiological factors such as spleen contraction, oxygen uptake, and sympathetic nerve activation compared to traditional warm-up methods. Immediate improvements in aerobic power suggest reduced vagus nerve stimulation, heightened sympathetic activity, and alterations in respiratory metabolism induced by the voluntarily hypoxia-triggered warm-up. Further research is warranted to comprehensively understand these physiological responses and optimize warm-up strategies for elite athletic performance.
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Affiliation(s)
- Wang Wendi
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
| | - Wu Dongzhe
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
| | - Wang Hao
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
| | - Shi Yongjin
- Department of Sports and Arts, China Agricultural University, Beijing, China
| | - Gao Xiaolin
- Sports Rehabilitation Research Center, China Institute of Sport Science, Beijing, China
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Vutien P, Li R, Karkar R, Munson SA, Fogarty J, Walter K, Yacoub M, Ioannou GN. Evaluating a Novel, Portable, Self-Administrable Device ("Beacon") That Measures Critical Flicker Frequency as a Test for Hepatic Encephalopathy. Am J Gastroenterol 2023; 118:1096-1100. [PMID: 36746413 PMCID: PMC10238616 DOI: 10.14309/ajg.0000000000002211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 01/26/2023] [Indexed: 02/08/2023]
Abstract
INTRODUCTION We compared critical flicker frequency (CFF) thresholds obtained using a novel portable device "Beacon" with thresholds from the commercially available Lafayette Flicker Fusion System (Lafayette-FFS) in patients with cirrhosis. METHODS One hundred fifty-three participants with chronic liver disease underwent CFF testing using Beacon and Lafayette-FFS with a method-of-limits and/or forced-choice protocol. RESULTS Beacon demonstrated excellent test-retest reliability (intraclass correlation 0.91-0.97) and good correlation with the Lafayette-FFS values (intraclass correlation 0.77-0.84). Forced-choice CFF were on average 4.1 Hz higher than method-of-limits descending CFFs. DISCUSSION Beacon can be self-administered by patients with chronic liver disease and cirrhosis to measure CFF, a validated screening test for minimal hepatic encephalopathy.
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Affiliation(s)
- Philip Vutien
- University of Washington, Division of Gastroenterology and Hepatology, Seattle, WA, USA
- Department of Medicine Veterans Affairs Puget Sound Healthcare System and University of Washington, Seattle, WA, USA
| | - Richard Li
- Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, WA, USA
| | - Ravi Karkar
- Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, WA, USA
- Manning College of Information and Computer Sciences, University of Massachusetts Amherst, Amherst, MA, USA
| | - Sean A. Munson
- Human Centered Design & Engineering, University of Washington, Seattle, WA, USA
| | - James Fogarty
- Paul G. Allen School of Computer Science & Engineering, University of Washington, Seattle, WA, USA
| | - Kara Walter
- University of Washington, Division of Gastroenterology and Hepatology, Seattle, WA, USA
| | - Michael Yacoub
- University of Washington, Division of Gastroenterology and Hepatology, Seattle, WA, USA
| | - George N. Ioannou
- University of Washington, Division of Gastroenterology and Hepatology, Seattle, WA, USA
- Department of Medicine Veterans Affairs Puget Sound Healthcare System and University of Washington, Seattle, WA, USA
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Muth T, Schipke JD, Brebeck AK, Dreyer S. Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:medicina59040800. [PMID: 37109758 PMCID: PMC10141404 DOI: 10.3390/medicina59040800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/13/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023]
Abstract
The critical flicker fusion frequency (cFFF) refers to the frequency at which a regularly recurring change of light stimuli is perceived as steady. The cFFF threshold is often assessed in clinics to evaluate the temporal characteristics of the visual system, making it a common test for eye diseases. Additionally, it serves as a helpful diagnostic tool for various neurological and internal diseases. In the field of diving/hyperbaric medicine, cFFF has been utilized to determine alertness and cognitive functions. Changes in the cFFF threshold have been linked to the influence of increased respiratory gas partial pressures, although there exist inconsistent results regarding this effect. Moreover, the use of flicker devices has produced mixed outcomes in previous studies. This narrative review aims to explore confounding factors that may affect the accuracy of cFFF threshold measurements, particularly in open-field studies. We identify five broad categories of such factors, including (1) participant characteristics, (2) optical factors, (3) smoking/drug use, (4) environmental aspects, and (5) breathing gases and partial pressures. We also discuss the application of cFFF measurements in the field of diving and hyperbaric medicine. In addition, we provide recommendations for interpreting changes in the cFFF threshold and how they are reported in research studies.
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Affiliation(s)
- Thomas Muth
- Institute of Occupational, Social, Environmental Medicine, Faculty of Medicine, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Jochen D Schipke
- Research Group Experimental Surgery, University Hospital Düsseldorf, 40225 Düsseldorf, Germany
| | | | - Sven Dreyer
- Hyperbaric Oxygen Therapy, University Hospital Düsseldorf, 40225 Düsseldorf, Germany
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de Asís-Fernández F, Sereno D, Turner AP, González-Mohíno F, González-Ravé JM. Effects of apnoea training on aerobic and anaerobic performance: A systematic review and meta-analysis. Front Physiol 2022; 13:964144. [PMID: 36237527 PMCID: PMC9551563 DOI: 10.3389/fphys.2022.964144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Background Trained breath-hold divers have shown physiological adaptations that might improve athletes’ aerobic and anaerobic performance.Objective This study aimed to systematically review the scientific literature and perform a meta-analysis to assess the effects of voluntary apnoea training on markers of anaerobic and aerobic performance, such as blood lactate and VO2max.Methods A literature search on three databases (Web of Science, PubMed and SCOPUS) was conducted in March 2022. The inclusion criteria were 1) peer-reviewed journal publication; 2) clinical trials; 3) healthy humans; 4) effects of apnoea training; 5) variables included markers of aerobic or anaerobic performance, such as lactate and VO2max.Results 545 manuscripts were identified following database examination. Only seven studies met the inclusion criteria and were, therefore, included in the meta-analysis. 126 participants were allocated to either voluntary apnoea training (ApT; n = 64) or normal breathing (NB; n = 63). Meta-analysis on the included studies demonstrated that ApT increased the peak blood lactate concentration more than NB (MD = 1.89 mmol*L−1 [95% CI 1.05, 2.73], z = 4.40, p < 0.0001). In contrast, there were no statistically significant effects of ApT on VO2max (MD = 0.89 ml*kg−1*min−1 [95% CI −1.23, 3.01], z = 0.82, p = 0.41).Conclusion ApT might be an alternative strategy to enhace anaerobic performance associated with increased maximum blood lactate; however, we did not find evidence of ApT effects on physiological aerobic markers, such as VO2max.Systematic Review Registration: [PRISMA], identifier [registration number].
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Affiliation(s)
- Francisco de Asís-Fernández
- Departamento de Fisioterapia, Facultad de Ciencias de la Salud, Centro Superior de Estudios Universitarios La Salle, Universidad Autónoma de Madrid, Madrid, Spain
- Breatherapy Research Group, Instituto de Neurociencias y Ciencias del Movimiento (INCIMOV), Centro Superior de Estudios Universitarios La Salle, Universidad Autónoma de Madrid, Madrid, Spain
| | - Daniel Sereno
- Breatherapy Research Group, Instituto de Neurociencias y Ciencias del Movimiento (INCIMOV), Centro Superior de Estudios Universitarios La Salle, Universidad Autónoma de Madrid, Madrid, Spain
- Sports Training Laboratory, Faculty of Sports Sciences, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Anthony P. Turner
- Sport, Physical Education and Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Fernando González-Mohíno
- Sports Training Laboratory, Faculty of Sports Sciences, Universidad de Castilla-La Mancha, Toledo, Spain
- Facultad de Ciencias de la Vida y de la Naturaleza, Universidad Nebrija, Madrid, Spain
- *Correspondence: Fernando González-Mohíno,
| | - José María González-Ravé
- Sports Training Laboratory, Faculty of Sports Sciences, Universidad de Castilla-La Mancha, Toledo, Spain
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