Publications by authors named "Lauren N Miutz"

8 Publications

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Concurrent Validity of a Stationary Cycling Test and Buffalo Concussion Treadmill Test in Adults with Concussion.

J Athl Train 2021 Apr 22. Epub 2021 Apr 22.

1Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.

Context: Following concussion, a multi-faceted assessment is recommended, including tests of physical exertion. The current gold standard for exercise testing following concussion is the Buffalo Concussion Treadmill Test (BCTT); however, there is a lack of validated tests that utilize alternative exercise modalities.

Objective: To assess the feasibility and concurrent validity of a novel cycling test of exertion compared to the BCTT.

Design: Crossover Study Setting: University Sport-Medicine Clinic Patients: Twenty adults (aged 18-60 years) diagnosed with a Sport-Related Concussion Intervention: Participants completed the BCTT and a cycling test of exertion in a random order, approximately 48 hours apart.

Main Outcome Measures: The primary outcome of interest was maximum heart rate [HRmax; beats per minute (bpm)]. Secondary outcomes of interest included whether the participant reached volitional fatigue (yes/no), symptom responsible for test cessation (Post Concussion Symptom Scale), and Symptom Severity on a Visual Scale (/10).

Results: Of the 20 participants, 19 (10 male, 9 female) completed both tests. One participant did not return for the second test and was excluded from the analysis. No adverse events were reported. The median HRmax for the BCTT [171 bpm; (IQR: 139-184bpm)] was not significantly different than the median HRmax for the Cycle [173 bpm; (IQR: 160-182)] (z=-0.63, p=0.53). For both tests, the three most frequently reported symptoms responsible for test cessation were Headache, Dizziness, and Pressure in the head. Of interest, the majority of participants (64%) reported a different symptom responsible for test cessation on each test.

Conclusion: The novel cycling test of exertion achieved similar HRmax and test duration and may be a suitable alternative to the BCTT. Future research to understand the physiological reason for the heterogeneity in symptoms responsible for test cessation is warranted.
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http://dx.doi.org/10.4085/1062-6050-0003.21DOI Listing
April 2021

The validity and reliability of ultra-short-term heart rate variability parameters and the influence of physiological covariates.

J Appl Physiol (1985) 2021 Apr 15. Epub 2021 Apr 15.

Faculty of Kinesiology, University of Calgary, Canada.

Background: Ultra-short-term (UST) heart rate variability (HRV) metrics have increasingly been proposed as surrogates for short-term HRV metrics. However, the concurrent validity, within-day reliability, and between-day reliability of UST HRV have yet to be comprehensively documented.

Methods: Thirty-six adults (18 males, age: 26 ± 5 years, BMI: 24 ± 3 kg/m)were recruited. Measures of HRV were quantified in a quiet-stance upright orthostatic position via three-lead electrocardiogram (ADInstruments, FE232 BioAmp). All short-term data recordings were 300-seconds in length and five UST time points (i.e., 30-seconds, 60-seconds, 120-seconds, 180-seconds, and 240-seconds) were extracted from the original 300-second recording. Bland-Altman plots with 95% limits of agreement, repeated measures ANOVA, and two-tailed paired t-tests demarcated differences between UST and short-term recordings. Linear regressions, coefficient of variation, intraclass correlation coefficients, and other tests examined the validity and reliability in both time- and frequency-domains.

Results: No group differences were noted between all short-term and UST measures, for either time- (all p>0.202) or frequency-domain metrics (all p>0.086). A longer recording duration was associated with augmented validity and reliability, that was less impacted by confounding influences from physiological variables (e.g., respiration rate, carbon dioxide end-tidals, and blood pressure). Conclusively, heart rate, time-domain, and relative frequency-domain HRV metrics were acceptable with recordings greater or equal to 60s, 240s, and 300s, respectively.

Conclusions: Future studies employing UST HRV metrics, should thoroughly understand the methodological requirements to obtain accurate results. Moreover, a conservative approach should be utilized regarding the minimum acceptable recording duration, which ensures valid/reliable HRV estimates are obtained.
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http://dx.doi.org/10.1152/japplphysiol.00955.2020DOI Listing
April 2021

What recording duration is required to provide physiologically valid and reliable dynamic cerebral autoregulation transfer functional analysis estimates?

Physiol Meas 2021 Mar 24. Epub 2021 Mar 24.

University of Calgary, Calgary, Alberta, CANADA.

Objective: Currently, a recording of 300-seconds is recommended to obtain accurate dynamic cerebral autoregulation estimates using transfer function analysis (TFA). Therefore, this investigation sought to explore the concurrent validity and the within- and between-day reliability of TFA estimates derived from shorter recording durations from squat-stand maneuvers.

Approach: Retrospective analyses were performed on 70 young, recreationally active or endurance-trained participants (17 females; age: 26±5 years, [range: 20-39 years]; body mass index: 24±3 kg/m2). Participants performed 300-seconds of squat-stands at frequencies of 0.05 and 0.10Hz, where shorter recordings of 60-, 120-, 180-, and 240-seconds were extracted. Continuous transcranial Doppler ultrasound recordings were taken within the middle and posterior cerebral arteries. Coherence, phase, gain, and normalized gain metrics were derived. Bland-Altman plots with 95% limits of agreement (LOA), repeated measures ANOVA's, two-tailed paired t-tests, coefficient of variation (CoV), Cronbach's alpha, intraclass correlation coefficients, and linear regressions were conducted.

Main Results: When examining the concurrent validity across different recording durations, group differences were noted within coherence (F(4,155)>11.6, p<0.001) but not phase (F(4,155)<0.27, p>0.611), gain (F(4,155)<0.61, p>0.440), or normalized gain (F(4,155)<0.85, p>0.359) parameters. The Bland-Altman 95% LOA measuring the concurrent validity, trended to narrow as recording duration increased (60-seconds:<±0.4, 120-seconds:<±0.3, 180-seconds <±0.3, 240-seconds:<±0.1). The validity of the 180- and 240-second recordings further increased when physiological covariates were included within regression models.

Significance: Future studies examining autoregulation should seek to have participants perform 300-seconds of squat-stand maneuvers. However, valid and reliable TFA estimates can be drawn from 240-seconds or 180-seconds recordings if physiological covariates are controlled.
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http://dx.doi.org/10.1088/1361-6579/abf1afDOI Listing
March 2021

A Standardized Buffalo Concussion Treadmill Test Following Sport-Related Concussion in Youth: Do ActiGraph Algorithms Matter?

J Athl Train 2021 Jan 22. Epub 2021 Jan 22.

1Sport Injury Prevention Research Center, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.

Context: Current recovery guidelines following sport-related concussion (SRC) include 24-48 hours of rest followed by gradual return-to-activity with heart rate (HR) maintained below symptom threshold. Additionally, the monitoring of physical activity (PA) post-SRC using ActiGraph accelerometers can provide further objective insight on amounts of activity associated with recovery trajectories. Cut-point algorithms for these devices allow minute-by-minute PA to be classified into intensity domains; however, studies have shown different algorithms employed on the same healthy participant dataset can produce varying classifications.

Objective: To identify the most physiologically appropriate cut-point algorithm (Evenson or Romanzini) to analyze ActiGraph data in concussed youth with comparisons to HR response on the Buffalo Concussion Treadmill Test (BCTT).

Design: Prospective cohort study.

Setting: Sport-concussion clinic within a university setting.

Patients Or Other Participants: Eleven high-school students (5 male, 6 female; median [range] age =16 years [15-17], height = 177.8 cm [157.5-198.1], weight = 67 kg [52-98], body mass index = 22 kg/m2 [17-31]) involved in high-risk sport who sustained a physician diagnosed SRC.

Main Outcome Measure(s): Evenson and Romanzini algorithm PA intensity domains via ActiGraph data and HR during the BCTT.

Results: There were differences in moderate (P = .001) and vigorous (P = .002) intensities between algorithms, but no difference in light (P = .548). Evenson classified most of the time as moderate intensity (57.03% [0.00-94.12%]), whereas Romanzini classified virtually all PA as vigorous (88.25% [2.94-97.06%]). PA based on HR (stages 1-7: 20-39% HR reserve (HRR), stages 8-13: 40-59% HRR, stages 14 and above: 60-85% HRR) indicated the BCTT primarily involves light-to-moderate intensity, and therefore is better represented by the Evenson algorithm.

Conclusions: The Evenson algorithm better characterizes the HR response during a standardized exercise test in concussed individuals and therefore should be used to analyze ActiGraph PA data in a concussed paediatric population.
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http://dx.doi.org/10.4085/527-20DOI Listing
January 2021

Changes in exertion-related symptoms in adults and youth who have sustained a sport-related concussion.

J Sci Med Sport 2021 Jan 21;24(1):2-6. Epub 2020 Jun 21.

Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Canada; Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Canada; Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Canada. Electronic address:

Objectives: To identify the symptoms responsible for cessation of exercise testing and evaluate changes in post-concussion symptom scores on the Post-Concussion Symptom Scale (PCSS) from the Sport-Concussion Assessment Tool (SCAT5) immediately, 1-4h, and 6-12h following completion of the Buffalo Concussion Treadmill Test (BCTT) in youth and adults who have sustained a sport-related concussion.

Design: Prospective case-series.

Methods: Individuals who were diagnosed with a sport-related concussion and self-reported difficulties with exertion were referred to perform an exertional treadmill test. Individuals were recruited from a university sports medicine clinic. Change in PCSS symptom severity scores were operationally defined as a change ≥4 points.

Results: Forty-five individuals aged 13-57 years consented to participate. A total of 14/24 (58.3%) female and 13/21 (61.9%) male participants reported an increase in symptom severity scores immediately following the BCTT. At 1-4h, 5/10 (50.0%) males and 5/14 (35.7%) females who completed the PCSS had elevated symptom severity scores compared to pre-exertion. Only 24.2% (3/17 males and 5/16 females) of participants completing the PCSS at 6-12h reported increased symptom severity scores.

Conclusion: Exertional testing is an important component of a multifaceted assessment following concussion; however, previous research evaluating symptom responses to exertion is limited. This study provides evidence to suggest individuals who experience an exacerbation of concussion-associated symptoms after exertion are likely to return to pre-exertion levels within the same day. Future research monitoring symptoms following exertion and throughout recovery should be performed in tandem with physiological measures to better understand the source of symptoms.
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http://dx.doi.org/10.1016/j.jsams.2020.06.005DOI Listing
January 2021

Baseline Performance of High School Rugby Players on the Sport Concussion Assessment Tool 5.

J Athl Train 2020 Feb 9;55(2):116-123. Epub 2020 Jan 9.

Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Canada.

Context: Version 5 of the Sport Concussion Assessment Tool (SCAT5) was released in 2017 with an additional 10-word list option in the memory section and additional instructions for completing the symptom scale.

Objective: To provide reference scores for high school rugby union players on the SCAT5, including immediate memory using the 10-word list, and examine how age, sex, and concussion history affected performance.

Design: Cross-sectional study.

Setting: Calgary, Alberta high schools.

Patients Or Other Participants: High school rugby union players (ages 15-18 years) participating in a 2018 season cohort study (n = 380, males = 210, females = 170).

Main Outcome Measure(s): Sport Concussion Assessment Tool 5 scores, including total number of symptoms (of 20), symptom severity (of 132), 10-word immediate memory (of 30), delayed memory (of 10), modified Standardized Assessment of Concussion (of 50), and balance examination (of 30).

Results: The median number of symptoms reported at baseline ranged from 5 to 8 across sex and age stratifications. Median symptom severity was lowest in males with no concussion history (7; range, 0-28) and highest in females with a concussion history (13, range = 0-45). Median total scores on immediate memory were 2-3 (range = 0-4) for males and 21 (range = 9-29) for females. Median total scores were 3 (range = 0-4) on digits backward and 7 (range = 0-20) on delayed memory (all groups). Based on simultaneous quantile (q) regression at 0.50 and 0.75, adjusted for age and concussion history, being female was associated with a higher total symptoms score (q0.75 β = 2.85; 99% confidence interval [CI] = 0.33, 5.37), higher total symptom severity score (q0.75 β = 8.00; 99% CI = 2.83, 13.17), and lower number of errors on the balance examination (q0.75 β = -3.00; 99% CI = -4.85, -1.15). Age and concussion history were not associated with any summary measures.

Conclusions: The 10-word list option in the memory section reduced the likelihood of a ceiling effect. A player's sex may be an important consideration when interpreting the SCAT5 after concussion.
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http://dx.doi.org/10.4085/1062-6050-123-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017900PMC
February 2020

Carbohydrate-restricted Diet and Exercise Increase Brain-derived Neurotrophic Factor and Cognitive Function: A Randomized Crossover Trial.

Cureus 2019 Sep 9;11(9):e5604. Epub 2019 Sep 9.

Preventive Medicine, College of Nursing, Grand Valley State University, Allendale, USA.

Introduction Metabolic syndrome (MetS) has been recognized as one of the most important clinical challenges and global health issues of today. Growing evidence suggests that mechanisms of energy metabolism may also play a key role in mediating aspects of cognitive function. Brain-derived neurotrophic factor (BDNF) is one such factor well known for its critical role in neuronal plasticity, including memory and learning, and more recently metabolic processes. BDNF levels have been shown separately to be dependent on diet and exercise programming. Purpose The purpose of this study was to investigate the effect of diet and exercise on BDNF levels and cognitive functioning with any metabolic association in individuals characterized with MetS. Methods Twelve subjects with MetS followed a randomized crossover design with two four-week interventions, including a carbohydrate (CHO)-restricted Paleolithic-based diet (CRPD; <50gCHO) with sedentary activity (CRPD-Sed) and CRPD with high intensity interval training (HIIT; CRPD-Sed), separated by a four-week washout period. The HIIT exercise consisted of 10 x 60 s cycling intervals interspersed with 60 s of active recovery 3 day/week for four-week. Serum BDNF was detected and quantified via enzyme-linked immunosorbent assay (ELISA). Cognitive executive function (Stroop Test) and self-perceived cognitive symptoms and function (MOS-CFS) were quantified. A two-way analysis of variance with repeated measures was performed with post-hoc analysis using simple effects analysis with a Bonferroni adjustment. The level of statistical significance was established a priori as P < 0.05. Results Compared to baseline, CRPD-Sed and CRPD-Ex improved variables for cognitive function, including increased peripheral serum BDNF levels (20% and 38%), psychomotor speed and cognitive flexibility (-14%, -14%), and self-perceived cognitive symptoms and functioning (+8%, +16%), respectively. BDNF inversely correlated with %body fat (r = -0.35, P < 0.05), fasting glucose (r = -0.64, P < 0.05), triglycerides (r = -0.55, P < 0.05), and insulin sensitivity (r = -0.25, P < 0.05). Conclusion This study shows the short-term beneficial effects of carbohydrate-restricted diet on serum BDNF and executive function in those individuals characterized with MetS. We have shown that the addition of exercise can further improve neuroprotection and cognitive function beyond the results of diet alone.
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http://dx.doi.org/10.7759/cureus.5604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822553PMC
September 2019

Carbohydrate-restricted Diet and High-intensity Interval Training Exercise Improve Cardio-metabolic and Inflammatory Profiles in Metabolic Syndrome: A Randomized Crossover Trial.

Cureus 2019 Sep 8;11(9):e5596. Epub 2019 Sep 8.

Preventive Medicine, College of Nursing, Grand Valley State University, Allendale, USA.

Introduction One approach to slow the pandemic of obesity and chronic disease is to look to our evolutionary past for clues of the changing behaviors contributing to the emergence of 'diseases of civilization'. Modern humans have deviated from the lifestyle behaviors of our ancestors that have introduced pressures (i.e. diet and activity changes) quicker than our genetic ability to respond. This caused a 'mismatch' between our biological systems and environment, leading to 'man-made' chronic diseases. Purpose The purpose of the study was to investigate the effects of a short-term evolutionarily informed dietary and lifestyle intervention on inflammatory and cardio-metabolic profiles in individuals characterized as having metabolic syndrome (MetS). Methods Twelve subjects with MetS followed a crossover design with two, four-week interventions, including a carbohydrate (CHO)-restricted Paleolithic-based diet (CRPD; <50g CHO) with sedentary activity (CRPD-Sed) and CRPD with high-intensity interval training (CRPD-Ex), separated by a four-week washout period. The HIIT exercise consisted of 10 X 60 seconds (s) cycling intervals interspersed with 60s of active recovery three d/wk for four weeks. The effects of a diet with sedentary activity as compared to a diet with exercise on body composition, as well as the cardiovascular, inflammatory, and metabolic profiles, were assessed. A two-way analysis of variance (ANOVA) with repeated measures was performed with a post-hoc analysis using a simple effects analysis with a Bonferroni adjustment. The level of statistical significance was established a priori as p < 0.05. Results Compared to baselines, CRPD-Sed and CRPD-Ex improved cardio-metabolic markers, including reductions in waist adiposity (-15%, -18%), body mass (-3%, -5%), body fat % (BF%; -7%, -12%), fasting plasma glucose (GLU; -20%, -27%), triglycerides (TG; -47%, -52%), fasting insulin (-34%, -39%), insulin resistance (-35%, -46%), and increased HDL-C (+22%, +36%) and VO (+22% and +29%), respectively. CRPD-Sed and CRPD-Ex also reduced inflammatory markers, including hsCRP (-32% and-36%), TNF-alpha (-35% and -41%), IL-6 (-29% and -40%), and ICAM-1 (-19%, -23%), respectively, when compared to baseline. Conclusion Adopting behaviors from our evolutionary past, including diet and exercise, shows favorable cardio-metabolic and inflammatory profiles in those individuals characterized with MetS.
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http://dx.doi.org/10.7759/cureus.5596DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822889PMC
September 2019