1
|
Correia ATL, Forshaw PE, Roden LC, Lipinska G, Rauch HGL, Lambert EV, Layden BT, Reutrakul S, Crowley SJ, Luke A, Dugas LR, Rae DE. Associations between fears related to safety during sleep and self-reported sleep in men and women living in a low-socioeconomic status setting. Sci Rep 2024; 14:3609. [PMID: 38351245 PMCID: PMC10864334 DOI: 10.1038/s41598-024-54032-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 02/07/2024] [Indexed: 02/16/2024] Open
Abstract
South Africans living in low socioeconomic areas have self-reported unusually long sleep durations (approximately 9-10 h). One hypothesis is that these long durations may be a compensatory response to poor sleep quality as a result of stressful environments. This study aimed to investigate whether fear of not being safe during sleep is associated with markers of sleep quality or duration in men and women. South Africans (n = 411, 25-50 y, 57% women) of African-origin living in an urban township, characterised by high crime and poverty rates, participated in this study. Participants are part of a larger longitudinal cohort study: Modelling the Epidemiologic Transition Study (METS)-Microbiome. Customised questions were used to assess the presence or absence of fears related to feeling safe during sleep, and the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index were used to assess daytime sleepiness, sleep quality and insomnia symptom severity respectively. Adjusted logistic regression models indicated that participants who reported fears related to safety during sleep were more likely to report poor sleep quality (PSQI > 5) compared to participants not reporting such fears and that this relationship was stronger among men than women. This is one of the first studies outside American or European populations to suggest that poor quality sleep is associated with fear of personal safety in low-SES South African adults.
Collapse
Affiliation(s)
- Arron T L Correia
- Health Through Physical Activity, Lifestyle and Sport (HPALS) Research Centre and Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7700, South Africa.
| | - Philippa E Forshaw
- Health Through Physical Activity, Lifestyle and Sport (HPALS) Research Centre and Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7700, South Africa
| | - Laura C Roden
- Centre for Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK
| | - Gosia Lipinska
- Department of Psychology, Humanities Faculty, University of Cape Town, Cape Town, South Africa
| | - H G Laurie Rauch
- Health Through Physical Activity, Lifestyle and Sport (HPALS) Research Centre and Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7700, South Africa
| | - Estelle V Lambert
- Health Through Physical Activity, Lifestyle and Sport (HPALS) Research Centre and Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7700, South Africa
| | - Brian T Layden
- Division of Endocrinology, Diabetes and Metabolism, University of Illinois Chicago, Chicago, IL, USA
- Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA
| | - Sirimon Reutrakul
- Division of Endocrinology, Diabetes and Metabolism, University of Illinois Chicago, Chicago, IL, USA
| | - Stephanie J Crowley
- Department of Psychiatry and Behavioral Sciences, Biological Rhythms Research Laboratory, Rush University Medical Center, Chicago, IL, USA
| | - Amy Luke
- Public Health Sciences, Parkinson School of Health Sciences and Public Health, Loyola University Chicago, Maywood, IL, USA
| | - Lara R Dugas
- Public Health Sciences, Parkinson School of Health Sciences and Public Health, Loyola University Chicago, Maywood, IL, USA
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Dale E Rae
- Health Through Physical Activity, Lifestyle and Sport (HPALS) Research Centre and Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, 7700, South Africa
| |
Collapse
|
2
|
Correia ATL, Lipinska G, Rauch HGL, Forshaw PE, Roden LC, Rae DE. Associations between sleep-related heart rate variability and both sleep and symptoms of depression and anxiety: A systematic review. Sleep Med 2023; 101:106-117. [PMID: 36370515 DOI: 10.1016/j.sleep.2022.10.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/05/2022] [Accepted: 10/20/2022] [Indexed: 11/07/2022]
Abstract
There is a bidirectional relationship between poor sleep and both mood- and anxiety-related disorders, which are among leading global health concerns. Additionally, both disordered sleep and these psychiatric disorders appear to be independently associated with altered autonomic nervous system (ANS) function. We hypothesise that ANS dysregulation during sleep may explain part of the relationship between poor sleep and mood- and anxiety-related disorders. Heart rate variability (HRV) is a frequently used marker of ANS function and gives an indication of ANS input to the heart - in particular, of the relative contributions of sympathetic and parasympathetic activity. A systematic review of PubMed, Scopus and Web of Science yielded 41 studies dealing with sleep, mood- and anxiety-related disorders and sleep-related HRV. Hyperarousal during sleep, reflecting a predominance of sympathetic activation and indicative of ANS dysregulation, may be an important factor in the association between poor sleep and mood-related disorders. Longitudinal studies and mediation analyses are necessary to further understand the potential mediating role of ANS dysregulation on the relationship between poor sleep and mood- and anxiety-related disorders.
Collapse
Affiliation(s)
- Arron T L Correia
- Health Through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa.
| | - Gosia Lipinska
- Department of Psychology, Faculty of Humanities, University of Cape Town, South Africa
| | - H G Laurie Rauch
- Health Through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa
| | - Philippa E Forshaw
- Health Through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa
| | - Laura C Roden
- Health Through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa; Research Centre for Sport, Exercise and Life Sciences, Faculty of Health and Life Sciences, Coventry University, United Kingdom
| | - Dale E Rae
- Health Through Physical Activity, Lifestyle and Sport Research Centre & Division of Physiological Sciences, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa
| |
Collapse
|
3
|
Rudner T, Hume DJ, Larmuth K, Atterbury E, Rauch HGL, Kroff J. Substance use disorder and obesogenic eating: Does working memory training strengthen ability to abstain from unwanted behaviors? A systematic review. J Subst Abuse Treat 2021; 137:108689. [PMID: 34952746 DOI: 10.1016/j.jsat.2021.108689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 10/06/2021] [Accepted: 12/07/2021] [Indexed: 01/03/2023]
Abstract
INTRODUCTION Abstaining from unwanted behaviors requires a sufficient balance between the executive and impulsive cognitive systems. Working memory (WM) is a vital component of both systems, identified in a wide range of research as the central and dominant component of executive function. WM potentially modulates the desires, tendencies, and behaviors specific to and seen in individuals with substance use disorder (SUD) and obesogenic eating (OE). Compared to healthy populations, research has shown individuals with SUD, as well as those who display OE, to have some degree of executive dysfunction, and both conditions have far-reaching health care implications. Additionally, these deficits are associated with impulsive behavior. Research has proposed that impulsive and so-called reward-driven responses could be altered through cognitive therapy and that both SUD and OE could benefit from working memory training (WMT). METHOD In this narrative review, we systematically align extant empirical reasoning and evidence with these assumptions. Our main aim is to ascertain and summarize the value of WMT for the treatment of both SUD and food reward consummatory behaviors. As a means to include detailed narrative accounts of all papers of potential value, our thresholds for meaningful improvements in both WM and unwanted behaviors are broad. RESULTS The results from the eleven qualifying studies are as follows: Nine of ten studies show a significant positive training effect of WMT on one or more components of WM capacity; three of six eligible papers (two on alcohol and one on opioid addiction) deliver notable improvements in SUD in response to WMT. One of two suitable studies showed WMT to be a moderately efficacious form of therapy for OE. Conversely, WMT appears to have negligible therapeutic benefit for cognitive function deficits or psychopathology unrelated to WM, suggesting that WMT has unique treatment efficacy for impulsive human behaviors. CONCLUSION In conclusion, more rigorous and uniform studies on WMT and impulsive harmful behaviors are required to give proof of the benefits of this potential useful treatment.
Collapse
Affiliation(s)
- Trinity Rudner
- Division of Exercise Science and Sports Medicine (ESSM), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - David J Hume
- Division of Exercise Science and Sports Medicine (ESSM), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Kate Larmuth
- Division of Exercise Science and Sports Medicine (ESSM), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Elizabeth Atterbury
- Division of Exercise Science and Sports Medicine (ESSM), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
| | - H G Laurie Rauch
- Division of Exercise Science and Sports Medicine (ESSM), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Jacolene Kroff
- Division of Exercise Science and Sports Medicine (ESSM), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; Health through Physical Activity, Lifestyle and Sport Research Centre (HPALS), Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa
| |
Collapse
|
4
|
Evans RW, Shackleton CL, West S, Derman W, Laurie Rauch HG, Baalbergen E, Albertus Y. Robotic Locomotor Training Leads to Cardiovascular Changes in Individuals With Incomplete Spinal Cord Injury Over a 24-Week Rehabilitation Period: A Randomized Controlled Pilot Study. Arch Phys Med Rehabil 2021; 102:1447-1456. [PMID: 33839105 DOI: 10.1016/j.apmr.2021.03.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 02/09/2021] [Accepted: 03/02/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To describe the effect of robotic locomotor training (RLT) and activity-based training (ABT) on cardiovascular indices during various physiological positions in individuals with spinal cord injury. DESIGN Randomized controlled pilot study. SETTING Private practice: Therapy & Beyond Centre - Walking with Brandon Foundation, Sports Science Institute of South Africa, Cape Town, South Africa. PARTICIPANTS Participants with chronic traumatic motor incomplete tetraplegia (N=16) who resided in the Western Cape, South Africa. INTERVENTION Robotic locomotor training (Ekso GT) and activity-based training over a 24-week intervention. MAIN OUTCOME MEASURES Brachial and ankle blood pressure, heart rate, heart rate variability, and cardiovascular efficiency during 4 physiological positions. RESULTS No differences between groups or over time were evident in resting systolic and diastolic blood pressure, ankle systolic pressure, ankle brachial pressure index, and heart rate variability. Standing heart rate at 24 weeks was significantly higher in the ABT group (95.58±12.61 beats/min) compared with the RLT group (75.14±14.96 beats/min) (P=.05). In the RLT group, no significant changes in heart rate variability (standard deviation R-R interval and root mean square of successive differences) was found between the standing and 6-minute walk test physiological positions throughout the intervention. Cardiovascular efficiency in the RLT group during the 6-minute walk test improved from 11.1±2.6 at baseline to 7.5±2.8 beats per meter walked at 6 weeks and was maintained from 6 to 24 weeks. CONCLUSIONS Large effect sizes and significant differences between groups found in this pilot study support the clinical effectiveness of RLT and ABT for changing cardiovascular indices as early as 6 weeks and up to 24 weeks of rehabilitation. RLT may be more effective than ABT in improving cardiac responses to orthostatic stress. Based on heart rate variability metrics, the stimulus of standing has comparable effects to RLT on the parasympathetic nervous system. Cardiovascular efficiency of exoskeleton walking improved, particularly over the first 6 weeks. Both the RLT and ABT interventions were limited in their effect on brachial and ankle blood pressure. A randomized controlled trial with a larger sample size is warranted to further examine these findings.
Collapse
Affiliation(s)
- Robert W Evans
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town
| | - Claire L Shackleton
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town
| | - Sacha West
- Department of Sport Management, Cape Peninsula University of Technology, Cape Town
| | - Wayne Derman
- Institute of Sport and Exercise Medicine, Division of Orthopaedic Surgery, Faculty of Medicine and Health Sciences, University of Stellenbosch, Cape Town; IOC Research Centre, South Africa
| | - H G Laurie Rauch
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town
| | - Ed Baalbergen
- Rehabilitation Unit, Life Vincent Pallotti Hospital, Cape Town, South Africa
| | - Yumna Albertus
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town.
| |
Collapse
|
5
|
Angelova M, Holloway PM, Shelyag S, Rajasegarar S, Rauch HGL. Effect of Stress on Cardiorespiratory Synchronization of Ironman Athletes. Front Physiol 2021; 12:612245. [PMID: 33737881 PMCID: PMC7960764 DOI: 10.3389/fphys.2021.612245] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/02/2021] [Indexed: 11/13/2022] Open
Abstract
The aim of this paper is to investigate the cardiorespiratory synchronization in athletes subjected to extreme physical stress combined with a cognitive stress tasks. ECG and respiration were measured in 14 athletes before and after the Ironman competition. Stroop test was applied between the measurements before and after the Ironman competition to induce cognitive stress. Synchrogram and empirical mode decomposition analysis were used for the first time to investigate the effects of physical stress, induced by the Ironman competition, on the phase synchronization of the cardiac and respiratory systems of Ironman athletes before and after the competition. A cognitive stress task (Stroop test) was performed both pre- and post-Ironman event in order to prevent the athletes from cognitively controlling their breathing rates. Our analysis showed that cardiorespiratory synchronization increased post-Ironman race compared to pre-Ironman. The results suggest that the amount of stress the athletes are recovering from post-competition is greater than the effects of the Stroop test. This indicates that the recovery phase after the competition is more important for restoring and maintaining homeostasis, which could be another reason for stronger synchronization.
Collapse
Affiliation(s)
- Maia Angelova
- D2I Research Centre, School of IT, Deakin University, Geelong, VIC, Australia
| | - Philip M Holloway
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Sergiy Shelyag
- D2I Research Centre, School of IT, Deakin University, Geelong, VIC, Australia
| | | | - H G Laurie Rauch
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| |
Collapse
|
6
|
Hume DJ, Howells FM, Karpul D, Rauch HGL, Kroff J, Lambert EV. Cognitive control over visual food cue saliency is greater in reduced-overweight/obese but not in weight relapsed women: An EEG study. Eat Behav 2015. [PMID: 26204099 DOI: 10.1016/j.eatbeh.2015.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Poor weight management may relate to a reduction in neurobehavioural control over food intake and heightened reactivity of the brain's neural reward pathways. Here we explore the neurophysiology of food-related visual cue processing in weight reduced and weight relapsed women by assessing differences in cortical arousal and attentional processing using a food-Stroop paradigm. METHODS 51 women were recruited into 4 groups: reduced-weight participants (RED, n=14) compared to BMI matched low-weight controls (LW-CTL, n=18); and weight relapsed participants (REL, n=10) compared to BMI matched high-weight controls (HW-CTL, n=9). Eating behaviour and body image questionnaires were completed. Two Stroop tasks (one containing food images, the other containing neutral images) were completed with record of electroencephalography (EEG). RESULTS Differences in cortical arousal were found in RED versus LW-CTL women, and were seen during food task execution only. Compared to their controls, RED women exhibited lower relative delta band power (p=0.01) and higher relative beta band power (p=0.01) over the right frontal cortex (F4). Within the RED group, delta band oscillations correlated positively with self-reported habitual fat intake and with body shape dissatisfaction. CONCLUSIONS As compared to women matched for phenotype but with no history of weight reduction, reduced-overweight/obese women show increased neurobehavioural control over external food cues and the inhibition of reward-orientated feeding responses. Insight into these self-regulatory mechanisms which attenuate food cue saliency may aid in the development of cognitive remediation therapies which facilitate long-term weight loss.
Collapse
Affiliation(s)
- David John Hume
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Newlands, 7725, South Africa.
| | - Fleur Margaret Howells
- Department of Psychiatry and Mental Health, Faculty of Health Sciences, University of Cape Town, Observatory, 7925, South Africa.
| | - David Karpul
- Bioelectronics & Neuroscience group, The MARCS Institute, University of Western Sydney, Penrith, NSW 2751, Australia.
| | - H G Laurie Rauch
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Newlands, 7725, South Africa.
| | - Jacolene Kroff
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Newlands, 7725, South Africa.
| | - Estelle Victoria Lambert
- Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Newlands, 7725, South Africa.
| |
Collapse
|
7
|
Howells FM, Laurie Rauch HG, Ives-Deliperi VL, Horn NR, Stein DJ. Mindfulness based cognitive therapy may improve emotional processing in bipolar disorder: pilot ERP and HRV study. Metab Brain Dis 2014; 29:367-75. [PMID: 24311196 DOI: 10.1007/s11011-013-9462-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/21/2013] [Indexed: 01/07/2023]
Abstract
Emotional processing in bipolar disorder (BD) is impaired. We aimed to measure the effects of mindfulness based cognitive-behavioral therapy (MBCT) in BD on emotional processing, as measured by event related potentials (ERP) and by heart rate variability (HRV). ERP and HRV were recorded during the completion of a visual matching task, which included object matching, affect matching, and affect labeling. Individuals with BD (n = 12) were compared with controls (n = 9) to obtain baseline data prior to the individuals with BD undergoing an 8-week MBCT intervention. ERP and HRV recording was repeated after the MBCT intervention in BD. Participants with BD had exaggerated ERP N170 amplitude and increased HRV HF peak compared to controls, particularly during the affect matching condition. After an 8-week MBCT intervention, participants with BD showed attenuation of ERP N170 amplitude and reduced HRV HF peak. Our findings support findings from the literature emphasizing that emotional processing in BD is altered, and suggesting that MBCT may improve emotional processing in BD.
Collapse
Affiliation(s)
- Fleur M Howells
- Department of Psychiatry, Faculty of Health Sciences, University of Cape Town, Observatory, 7925, South Africa,
| | | | | | | | | |
Collapse
|
8
|
Prinsloo GE, Rauch HGL, Derman WE. A brief review and clinical application of heart rate variability biofeedback in sports, exercise, and rehabilitation medicine. PHYSICIAN SPORTSMED 2014; 42:88-99. [PMID: 24875976 DOI: 10.3810/psm.2014.05.2061] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CONTEXT An important component of the effective management of chronic noncommunicable disease is the assessment and management of psychosocial stress. The measurement and modulation of heart rate variability (HRV) may be valuable in this regard. OBJECTIVE To describe the measurement and physiological control of HRV; to describe the impact of psychosocial stress on cardiovascular disease, metabolic syndrome, and chronic respiratory disease, and the relationship between these diseases and changes in HRV; and to describe the influence of biofeedback and exercise on HRV and the use of HRV biofeedback in the management of chronic disease. DATA SOURCES AND STUDY SELECTION The PubMed, Medline, and Embase databases were searched (up to August 2013). Additional articles were obtained from the reference lists of relevant articles and reviews. Articles were individually selected for further review based on the quality and focus of the study, and the population studied. RESULTS Heart rate variability is reduced in stress and in many chronic diseases, and may even predict the development and prognosis of some diseases. Heart rate variability can be increased with both exercise and biofeedback. Although the research on the effect of exercise is conflicting, there is evidence that aerobic training may increase HRV and cardiac vagal tone both in healthy individuals and in patients with disease. Heart rate variability biofeedback is also an effective method of increasing HRV and cardiac vagal tone, and has been shown to decrease stress and reduce the morbidity and mortality of disease. CONCLUSION The assessment and management of psychosocial stress is a challenging but important component of effective comprehensive lifestyle interventions for the management of noncommunicable disease. It is, therefore, important for the sports and exercise physician to have an understanding of the therapeutic use of HRV modulation, both in the reduction of stress and in the management of chronic disease.
Collapse
Affiliation(s)
- Gabriell E Prinsloo
- MRC/UCT Research Unit for Exercise Science and Sports Medicine, University of Cape Town, Cape Town, South Africa.
| | | | | |
Collapse
|
9
|
Prinsloo GE, Derman WE, Lambert MI, Rauch HGL. The effect of a single episode of short duration heart rate variability biofeedback on measures of anxiety and relaxation states. International Journal of Stress Management 2013. [DOI: 10.1037/a0034777] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
10
|
Prinsloo GE, Rauch HGL, Lambert MI, Muench F, Noakes TD, Derman WE. The effect of short duration heart rate variability (HRV) biofeedback on cognitive performance during laboratory induced cognitive stress. Appl Cognit Psychol 2010. [DOI: 10.1002/acp.1750] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
11
|
Abstract
INTRODUCTION In this study we examined the pacing strategy and the end muscle glycogen contents in eight cyclists, once when they were carbohydrate loaded and once when they were non-loaded. METHODS Cyclists completed 2 hours of cycling at approximately 73% of maximum oxygen consumption, which included five sprints at 100% of peak sustained power output every 20 minutes, followed immediately by a 1 hour time trial. Muscle biopsies were performed before and immediately after exercise, while blood samples were taken during the 2 hour steady state rides and immediately after exercise. RESULTS Carbohydrate loading improved mean power output during the 1 hour time trial (mean (SEM) 219 (17) v 233 (15) W; p<0.05) and enabled subjects to use significantly more muscle glycogen than during the trial following their normal diet. Significantly, the subjects, kept blind to all feedback except for time, started both time trials at similar workloads ( approximately 30 W), but after 1 minute of cycling, the workload average 14 W higher throughout the loaded compared with the non-loaded time trial. There were no differences in subjects' plasma glucose and lactate concentrations and heart rates in the carbohydrate loaded versus the non-loaded trial. Of the eight subjects, seven improved their time trial performance after carbohydrate loading. Finishing muscle glycogen concentrations in these seven subjects were remarkably similar in both trials (18 (3) v 20 (3) mmol/kg w/w), despite significantly different starting values and time trial performances (36.55 (1.47) v 38.14 (1.27) km/h; p<0.05). The intra-subject coefficient of variation (CV) for end glycogen content in these seven subjects was 10%, compared with an inter-subject CV of 43%. CONCLUSIONS As seven subjects completed the time trials with the same end exercise muscle glycogen concentrations, diet induced changes in pacing strategies during the time trials in these subjects may have resulted from integrated feedback from the periphery, perhaps from glycogen content in exercising muscles.
Collapse
Affiliation(s)
- H G L Rauch
- UCT/MRC Research Unit for Exercise Science and Sports Medicine, Sports Science Institute, Boundary Road, Newlands, Cape Town 7700, South Africa.
| | | | | | | |
Collapse
|