Publications by authors named "Bryan Haddock"

31 Publications

Assessment of functional sit-to-stand muscle power: Cross-sectional trajectories across the lifespan.

Exp Gerontol 2021 Sep 9;152:111448. Epub 2021 Jun 9.

Geriatric Research Unit, Geriatric Department, Bispebjerg University Hospital, Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet-Glostrup University Hospital, Copenhagen, Denmark; Geriatric Research Unit, Department of Internal Medicine, Herlev-Gentofte University Hospital, Copenhagen, Denmark. Electronic address:

Background: The 30-s sit-to-stand (STS) muscle power test is a valid test to assess muscle power in older people; however, whether it may be used to assess trajectories of lower-limb muscle power through the adult lifespan is not known. This study evaluated the pattern and time course of variations in relative, allometric and specific STS muscle power throughout the lifespan.

Methods: Subjects participating in the Copenhagen Sarcopenia Study (729 women and 576 men; aged 20 to 93 years) were included. Lower-limb muscle power was assessed with the 30-s version of the STS muscle power test. Allometric, relative and specific STS power were calculated as absolute STS power normalized to height squared, body mass and leg lean mass as assessed by DXA, respectively.

Results: Relative STS muscle power tended to increase in women (0.08 ± 0.05 W·kg·yr; p = 0.082) and increased in men (0.14 ± 0.07 W·kg·yr; p = 0.046) between 20 and 30 years, followed by a slow decline (-0.05 ± 0.05 W·kg·yr and -0.06 ± 0.08 W·kg·yr, respectively; both p > 0.05) between 30 and 50 years. Then, relative STS power declined at an accelerated rate up to oldest age in men (-0.09 ± 0.02 W·kg·yr) and in women until the age of 75 (-0.09 ± 0.01 W·kg·yr) (both p < 0.001). A lower rate of decline was observed in women aged 75 and older (-0.04 ± 0.02 W·kg·yr; p = 0.039). Similar age-related patterns were noted for allometric and specific STS power.

Conclusions: The STS muscle power test appears to provide a feasible and inexpensive tool to monitor cross-sectional trajectories of muscle power throughout the lifespan.
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http://dx.doi.org/10.1016/j.exger.2021.111448DOI Listing
September 2021

Exercise-induced fluid shifts are distinct to exercise mode and intensity: a comparison of blood flow-restricted and free-flow resistance exercise.

J Appl Physiol (1985) 2021 06 29;130(6):1822-1835. Epub 2021 Apr 29.

Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, grid.4973.9Copenhagen University Hospital, Copenhagen, Denmark.

MRI can provide fundamental tools in decoding physiological stressors stimulated by training paradigms. Acute physiological changes induced by three diverse exercise protocols known to elicit similar levels of muscle hypertrophy were evaluated using muscle functional magnetic resonance imaging (mfMRI). The study was a cross-over study with participants ( = 10) performing three acute unilateral knee extensor exercise protocols to failure and a work matched control exercise protocol. Participants were scanned after each exercise protocol; 70% 1 repetition maximum (RM) (FF70); 20% 1RM (FF20); 20% 1RM with blood flow restriction (BFR20); free-flow (FF) control work matched to BFR20 (FF20). Post exercise mfMRI scans were used to obtain interleaved measures of muscle R2 (indicator of edema), R2' (indicator of deoxyhemoglobin), muscle cross sectional area (CSA) blood flow, and diffusion. Both BFR20 and FF20 exercise resulted in a larger acute decrease in R2, decrease in R2', and expansion of the extracellular compartment with slower rates of recovery. BFR20 caused greater acute increases in muscle CSA than FF20 and FF70. Only BFR20 caused acute increases in intracellular volume. Postexercise muscle blood flow was higher after FF70 and FF20 exercise than BFR20. Acute changes in mean diffusivity were similar across all exercise protocols. This study was able to differentiate the acute physiological responses between anabolic exercise protocols. Low-load exercise protocols, known to have relatively higher energy contributions from glycolysis at task failure, elicited a higher mfMRI response. Noninvasive mfMRI represents a promising tool for decoding mechanisms of anabolic adaptation in muscle. Using muscle functional MRI (mfMRI), this study was able to differentiate the acute physiological responses following three established hypertrophic resistance exercise strategies. Low-load exercise protocols performed to failure, with or without blood flow restriction, resulted in larger changes in R (i.e. greater T-shifts) with a slow rate of return to baseline indicative of myocellular fluid shifts. These data were cross evaluated with interleaved measures of macrovascular blood flow, water diffusion, muscle cross sectional area (i.e. acute macroscopic muscle swelling), and intracellular water fraction measured using MRI.
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http://dx.doi.org/10.1152/japplphysiol.01012.2020DOI Listing
June 2021

Consensus-Based Technical Recommendations for Clinical Translation of Renal Phase Contrast MRI.

J Magn Reson Imaging 2020 Nov 2. Epub 2020 Nov 2.

Department of Bioengineering, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy.

Background: Phase-contrast (PC) MRI is a feasible and valid noninvasive technique to measure renal artery blood flow, showing potential to support diagnosis and monitoring of renal diseases. However, the variability in measured renal blood flow values across studies is large, most likely due to differences in PC-MRI acquisition and processing. Standardized acquisition and processing protocols are therefore needed to minimize this variability and maximize the potential of renal PC-MRI as a clinically useful tool.

Purpose: To build technical recommendations for the acquisition, processing, and analysis of renal 2D PC-MRI data in human subjects to promote standardization of renal blood flow measurements and facilitate the comparability of results across scanners and in multicenter clinical studies.

Study Type: Systematic consensus process using a modified Delphi method.

Population: Not applicable.

Sequence Field/strength: Renal fast gradient echo-based 2D PC-MRI.

Assessment: An international panel of 27 experts from Europe, the USA, Australia, and Japan with 6 (interquartile range 4-10) years of experience in 2D PC-MRI formulated consensus statements on renal 2D PC-MRI in two rounds of surveys. Starting from a recently published systematic review article, literature-based and data-driven statements regarding patient preparation, hardware, acquisition protocol, analysis steps, and data reporting were formulated.

Statistical Tests: Consensus was defined as ≥75% unanimity in response, and a clear preference was defined as 60-74% agreement among the experts.

Results: Among 60 statements, 57 (95%) achieved consensus after the second-round survey, while the remaining three showed a clear preference. Consensus statements resulted in specific recommendations for subject preparation, 2D renal PC-MRI data acquisition, processing, and reporting.

Data Conclusion: These recommendations might promote a widespread adoption of renal PC-MRI, and may help foster the set-up of multicenter studies aimed at defining reference values and building larger and more definitive evidence, and will facilitate clinical translation of PC-MRI.

Level Of Evidence: 1 TECHNICAL EFFICACY STAGE: 1.
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http://dx.doi.org/10.1002/jmri.27419DOI Listing
November 2020

Relation between leg extension power and 30-s sit-to-stand muscle power in older adults: validation and translation to functional performance.

Sci Rep 2020 10 1;10(1):16337. Epub 2020 Oct 1.

Geriatric Research Unit, Department of Geriatric and Palliative Medicine, Bispebjerg-Frederiksberg University Hospital, Copenhagen, Denmark.

This study aimed to assess the validity and functional relevance of a standardized procedure to assess lower limb muscle power by means of the 30-s sit-to-stand (STS) test when compared to leg extension power (LEP), traditional STS performance and handgrip strength. A total of 628 community-dwelling older subjects (60-93 years) from the Copenhagen Sarcopenia Study were included. Physical performance was assessed by the 30-s STS and 10-m maximal gait speed tests. Handgrip strength and LEP were recorded by a hand-held dynamometer and the Nottingham power rig, respectively. STS muscle power was calculated using the subjects' body mass and height, chair height and the number of repetitions completed in the 30-s STS test. We found a small albeit significant difference between LEP and unilateral STS power in older men (245.5 ± 88.8 vs. 223.4 ± 81.4 W; ES = 0.26; p < 0.05), but not in older women (135.9 ± 51.9 vs. 138.5 ± 49.6 W; ES = 0.05; p > 0.05). Notably, a large positive correlation was observed between both measures (r = 0.75; p < 0.001). Relative STS power was more strongly related with maximal gait speed than handgrip strength, repetition-based STS performance and relative LEP after adjusting for age (r = 0.53 vs 0.35-0.45; p < 0.05). In conclusion, STS power obtained from the 30-s STS test appeared to provide a valid measure of bilateral lower limb power and was more strongly related with physical performance than maximal handgrip strength, repetition-based STS performance and LEP.
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http://dx.doi.org/10.1038/s41598-020-73395-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7529789PMC
October 2020

Physiological responses of human skeletal muscle to acute blood flow restricted exercise assessed by multimodal MRI.

J Appl Physiol (1985) 2020 10 27;129(4):748-759. Epub 2020 Aug 27.

Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.

Important physiological quantities for investigating muscle hypertrophy include blood oxygenation, cell swelling, and changes in blood flow. The purpose of this study was to compare the acute changes of these parameters in human skeletal muscle induced by low-load (20% 1-RM) blood flow-restricted (BFR-20) knee extensor exercise compared with free-flow work-matched (FF-20) and free-flow 50% 1-RM (FF-50) knee extensor exercise using multimodal magnetic resonance imaging (MRI). Subjects ( = 11) completed acute exercise sessions for each exercise mode in an MRI scanner, where interleaved measures of muscle (indicator of edema), [Formula: see text] (indicator of deoxyhemoglobin), macrovascular blood flow, and diffusion were performed before, between sets, and after the final set for each exercise protocol. BFR-20 exercise resulted in larger acute decreases in R and greater increases in cross-sectional area than FF-20 and FF-50 ( < 0.01). Blood oxygenation decreased between sets during BFR-20, as indicated by a 13.6% increase in [Formula: see text] values ( < 0.01)), whereas they remained unchanged for FF-20 and decreased during FF-50 exercise. Quadriceps blood flow between sets was highest for the heavier load (FF-50), averaging 305 mL/min, and lowest for BFR-20 at 123 ± 73 mL/min until post-exercise cuff release, where blood flow rates in BFR-20 exceeded both FF protocols ( < 0.01). Acute changes in diffusion rates were similar for all exercise protocols. This study was able to differentiate the acute exercise response of selected physiological factors associated with skeletal muscle hypertrophy. Marked differences in these parameters were found to exist between BFR and FF exercise conditions, which contribute to explain the anabolic potential of low-load blood flow restricted muscle exercise. Acute changes in blood flow, diffusion, blood oxygenation, cross-sectional area, and the "T shift" are evaluated in human skeletal muscle in response to blood flow-restricted (BFR) and conventional free-flow knee extensor exercise performed in an MRI scanner. The acute physiological response to exercise was dependent on the magnitude of load and the application of BFR. Physiological variables changed markedly and established a steady state rapidly after the first of four exercise sets.
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http://dx.doi.org/10.1152/japplphysiol.00171.2020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7654733PMC
October 2020

Obesity does not modulate men's eating behavior after a high intensity interval exercise session: an exercise trial.

J Sports Med Phys Fitness 2021 Feb 23;61(2):280-286. Epub 2020 Jul 23.

Department of Kinesiology, California State University, San Bernardino, CA, USA.

Background: We investigated the impact of obesity on responses to high intensity interval exercise (HIIE) on hunger and energy intake (EI) in young men.

Methods: Ten men with obesity (OB) (Body Mass Index [BMI]: 34.6±4.4 kg/m) and 10 with normal weight (CG) (BMI: 23.1±3.9 kg/m) participated in a HIIE session. The session consisted of 6 rounds performed at 100% of maximum aerobic velocity (MAV) for 30 seconds, followed by 30 seconds of active recovery at 50% MAV and concluded with 4 minutes of passive recovery. This was repeated three times. EI was estimated at baseline and 24 h-post-HIIE. Hunger was measured at baseline, 2 h- and 24 h-post HIIE.

Results: Carbohydrate (CHO) intake increased in both groups (P<0.01). Hunger feelings (19.5 [0-50] mm at baseline to 50 [9-73] mm post-2 h and 60 [8-92] mm in post-24 h [group: P=0.71, time: P<0.01, group × time: P=0.06]) and a desire to eat (34 [1-89] ±36.0 mm at baseline to 63 [11-86] mm post-2 h and 51 [7-84] mm post-24 h [group: P=0.65, time: P<0.01, group × time: P=0.29]) increased in both groups.

Conclusions: Weight status does not modulate hunger and EI post-HIIE. However, the compensatory increase in CHO intake and hunger feelings is particularly noteworthy for health professionals.
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http://dx.doi.org/10.23736/S0022-4707.20.11181-2DOI Listing
February 2021

Age- and Sex-Specific Changes in Lower-Limb Muscle Power Throughout the Lifespan.

J Gerontol A Biol Sci Med Sci 2020 06;75(7):1369-1378

Geriatric Research Unit, Geriatric Department, Bispebjerg University Hospital, Copenhagen, Denmark.

Background: Our main goal was to evaluate the pattern and time course of changes in relative muscle power and its constituting components throughout the life span.

Methods: A total of 1,305 subjects (729 women and 576 men; aged 20-93 years) participating in the Copenhagen Sarcopenia Study took part. Body mass index (BMI), leg lean mass assessed by dual-energy X-ray absorptiometry (DXA), and leg extension muscle power (LEP) assessed by the Nottingham power rig were recorded. Relative muscle power (normalized to body mass) and specific muscle power (normalized to leg lean mass) were calculated. Segmented regression analyses were used to identify the onset and pattern of age-related changes in the recorded variables.

Results: Relative muscle power began to decline above the age of 40 in both women and men, with women showing an attenuation of the decline above 75 years. Relative muscle power decreased with age due to (i) the loss of absolute LEP after the fourth decade of life and (ii) the increase in BMI up to the age of 75 years in women and 65 years in men. The decline in absolute LEP was caused by a decline in specific LEP up to the age of 75 in women and 65 in men, above which the loss in relative leg lean mass also contributed.

Conclusions: Relative power decreased (i) above 40 years by the loss in absolute power (specific power only) and the increase in body mass, and (ii) above ~70 years by the loss in absolute power (both specific power and leg lean mass).
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http://dx.doi.org/10.1093/gerona/glaa013DOI Listing
June 2020

Episodic and Chronic Cluster Headache: Differences in Family History, Traumatic Head Injury, and Chronorisk.

Headache 2020 03 23;60(3):515-525. Epub 2019 Dec 23.

The Danish Headache Center, Department of Neurology, Rigshospitalet-Glostrup, Glostrup, Denmark.

Objective And Background: The diagnostic criteria of episodic and chronic cluster headache (cCH) were recently modified, yet pathophysiological differences between the two are still unclear. The aim of this cross-sectional study is to identify and characterize other differences between episodic and cCH.

Methods: Data from a retrospective, questionnaire- and interview-based study were analyzed with a focus on associated factors including traumatic head injury (THI), familial history, and change of phenotype. Attack patterns were analyzed using Gaussian and spectral modeling.

Results: 400 patients and 200 controls participated. A positive family history was more prevalent in chronic than episodic cluster headache (eCH) (34/146 (23%) vs 33/253 (13%), respectively, P = .008). A history of THI was more common in patients than controls (173/400 (43%) vs 51/200 (26%), respectively, P < .0001) and in chronic compared to eCH (77/146 (53%) vs 96/253 (37%), respectively, P = .004). Patients with a positive family history had a unique diurnal attack pattern with twice the risk of nocturnal attacks as patients who did not report family history. Patients reporting phenotype change had a chronobiological fingerprint similar to the phenotype they had experienced a transition into. A higher attack frequency in chronic patients was the only difference in symptom manifestation across all analyzed subgroups of patients.

Conclusions: cCH is associated with a positive family history and THI. In familial CH, a peak in nocturnal chronorisk may implicate genes involved in diurnal-, sleep- and homeostatic regulation. The stereotypical nature of the CH attacks themselves is confirmed and differences between subgroups should be sought in other characteristics.
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http://dx.doi.org/10.1111/head.13730DOI Listing
March 2020

A Nordic survey of CT doses in hybrid PET/CT and SPECT/CT examinations.

EJNMMI Phys 2019 Dec 16;6(1):24. Epub 2019 Dec 16.

Medical Radiation Physics, Department of Translational Medicine, Lund university, Inga Marie Nilssons gata 49, 20502, Malmö, Sweden.

Background: Computed tomography (CT) scans are routinely performed in positron emission tomography (PET) and single photon emission computed tomography (SPECT) examinations globally, yet few surveys have been conducted to gather national diagnostic reference level (NDRL) data for CT radiation doses in positron emission tomography/computed tomography (PET/CT) and single photon emission computed tomography/computed tomography (SPECT/CT). In this first Nordic-wide study of CT doses in hybrid imaging, Nordic NDRL CT doses are suggested for PET/CT and SPECT/CT examinations specific to the clinical purpose of CT, and the scope for optimisation is evaluated. Data on hybrid imaging CT exposures and clinical purpose of CT were gathered for 5 PET/CT and 8 SPECT/CT examinations via designed booklet. For each included dataset for a given facility and scanner type, the computed tomography dose index by volume (CTDI) and dose length product (DLP) was interpolated for a 75-kg person (referred to as CTDI and DLP). Suggested NDRL (75th percentile) and achievable doses (50th percentile) were determined for CTDI and DLP according to clinical purpose of CT. Differences in maximum and minimum doses (derived for a 75-kg patient) between facilities were also calculated for each examination and clinical purpose.

Results: Data were processed from 83 scanners from 43 facilities. Data were sufficient to suggest Nordic NDRL CT doses for the following: PET/CT oncology (localisation/characterisation, 15 systems); infection/inflammation (localisation/characterisation, 13 systems); brain (attenuation correction (AC) only, 11 systems); cardiac PET/CT and SPECT/CT (AC only, 30 systems); SPECT/CT lung (localisation/characterisation, 12 systems); bone (localisation/characterisation, 30 systems); and parathyroid (localisation/characterisation, 13 systems). Great variations in dose were seen for all aforementioned examinations. Greatest differences in DLP for each examination, specific to clinical purpose, were as follows: SPECT/CT lung AC only (27.4); PET/CT and SPECT/CT cardiac AC only (19.6); infection/inflammation AC only (18.1); PET/CT brain localisation/characterisation (16.8); SPECT/CT bone localisation/characterisation (10.0); PET/CT oncology AC only (9.0); and SPECT/CT parathyroid localisation/characterisation (7.8).

Conclusions: Suggested Nordic NDRL CT doses are presented according to clinical purpose of CT for PET/CT oncology, infection/inflammation, brain, PET/CT and SPECT/CT cardiac, and SPECT/CT lung, bone, and parathyroid. The large variation in doses suggests great scope for optimisation in all 8 examinations.
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http://dx.doi.org/10.1186/s40658-019-0266-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6915162PMC
December 2019

Consensus-based technical recommendations for clinical translation of renal T1 and T2 mapping MRI.

MAGMA 2020 Feb 22;33(1):163-176. Epub 2019 Nov 22.

Department of Radiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

To develop technical recommendations on the acquisition and post-processing of renal longitudinal (T1) and transverse (T2) relaxation time mapping. A multidisciplinary panel consisting of 18 experts in the field of renal T1 and T2 mapping participated in a consensus project, which was initiated by the European Cooperation in Science and Technology Action PARENCHIMA CA16103. Consensus recommendations were formulated using a two-step modified Delphi method. The first survey consisted of 56 items on T1 mapping, of which 4 reached the pre-defined consensus threshold of 75% or higher. The second survey was expanded to include both T1 and T2 mapping, and consisted of 54 items of which 32 reached consensus. Recommendations based were formulated on hardware, patient preparation, acquisition, analysis and reporting. Consensus-based technical recommendations for renal T1 and T2 mapping were formulated. However, there was considerable lack of consensus for renal T1 and particularly renal T2 mapping, to some extent surprising considering the long history of relaxometry in MRI, highlighting key knowledge gaps that require further work. This paper should be regarded as a first step in a long-term evidence-based iterative process towards ever increasing harmonization of scan protocols across sites, to ultimately facilitate clinical implementation.
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http://dx.doi.org/10.1007/s10334-019-00797-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7021750PMC
February 2020

The Copenhagen Sarcopenia Study: lean mass, strength, power, and physical function in a Danish cohort aged 20-93 years.

J Cachexia Sarcopenia Muscle 2019 12 16;10(6):1316-1329. Epub 2019 Aug 16.

Department of Clinical Physiology and Nuclear Medicine, Bispebjerg-Frederiksberg University Hospital, Copenhagen, Denmark.

Background: Despite no international consensus on the diagnostic criteria for sarcopenia, low lean mass, muscle strength, and physical function are important risk factors for disability, frailty, and mortality in older individuals, as well as in a wide range of patients with muscle loss. Here, we provide a population-based reference material of total and regional lean body mass, muscle strength/power parameters, and physical function in a healthy cohort of Danish men and women across the lifespan.

Methods: Volunteers aged 20-93 years from the Copenhagen City Heart Study were invited to establish a Danish reference material (Copenhagen Sarcopenia Study) on lean mass characteristics [appendicular lean mass (ALM), iDXA, GE Lunar], muscle function [handgrip strength (HGS), Jamar dynamometer and leg extension power (LEP), Nottingham Power Rig], and physical function [30 s sit-to-stand test (STS), 10-m maximal and habitual gait speed (GS)].

Results: A total of 1305 participants [729 women (age: 56.4 ± 18.9 years, height: 1.66 ± 0.01 m, body mass index: 24.6 ± 4.3 kg/m and 576 men, age: 57.0 ± 17.5 years, height: 1.80 ± 0.07 m, body mass index: 26.0 ± 3.9 kg/m ] completed all measurements and were included in the present analysis. Lean mass characteristics (TLM, ALM, and ALM/h ) decreased with increasing age in both men and women (P < 0.001). Men demonstrated larger absolute and relative total ALM and higher HGS and LEP compared with women at all age intervals (P < 0.001). HGS and LEP decreased progressively with age in both men and women (P < 0.01); 30 s STS performance, habitual GS, and maximal GS decreased at an accellerated rate of decline with increasing age in both men and women (P < 0.001). Habitual GS was reduced in men and women aged ≥70 years, while maximal GS was reduced from the age of ≥60 years compared with young adults (P < 0.001). Regardless of sex, 30 s STS was reduced from the age of ≥50 years compared with the young reference group (P < 0.001) CONCLUSIONS: While the power-based measurements (LEP and 30 s STS) started to decline already at age +50 years, less power-based parameters (GS and HGS) and lean mass characteristics (TLM, ALM, and ALM/h ) remained unaltered until after the age of +70 years. Notably, the cut-off thresholds derived in the present study differed from earlier reference data, which underlines the importance of obtaining updated and local reference materials.
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http://dx.doi.org/10.1002/jcsm.12477DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6903448PMC
December 2019

Assessment of acute bone loading in humans using [F]NaF PET/MRI.

Eur J Nucl Med Mol Imaging 2019 Nov 5;46(12):2452-2463. Epub 2019 Aug 5.

Department of Radiology, Stanford University, Stanford, CA, USA.

Purpose: The acute effect of loading on bone tissue and physiology can offer important information with regard to joint function in diseases such as osteoarthritis. Imaging studies using [F]-sodium fluoride ([F]NaF) have found changes in tracer kinetics in animals after subjecting bones to strain, indicating an acute physiological response. The aim of this study is to measure acute changes in NaF uptake in human bone due to exercise-induced loading.

Methods: Twelve healthy subjects underwent two consecutive 50-min [F]NaF PET/MRI examinations of the knees, one baseline followed by one post-exercise scan. Quantification of tracer kinetics was performed using an image-derived input function from the popliteal artery. For both scans, kinetic parameters of K, K, k, k, and blood volume were mapped parametrically using nonlinear regression with the Hawkins model. The kinetic parameters along with mean SUV and SUV were compared between the pre- and post-exercise examinations. Differences in response to exercise were analysed between bone tissue types (subchondral, cortical, and trabecular bone) and between regional subsections of knee subchondral bone.

Results: Exercise induced a significant (p < <0.001) increase in [F]NaF uptake in all bone tissues in both knees, with mean SUV increases ranging from 47% in trabecular bone tissue to 131% in subchondral bone tissue. Kinetic parameters involving vascularization (K and blood volume) increased, whereas the NaF extraction fraction [k/(k + k)] was reduced.

Conclusions: Bone loading induces an acute response in bone physiology as quantified by [F]NaF PET kinetics. Dynamic imaging after bone loading using [F]NaF PET is a promising diagnostic tool in bone physiology and imaging of biomechanics.
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http://dx.doi.org/10.1007/s00259-019-04424-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6813760PMC
November 2019

Human renal response to furosemide: Simultaneous oxygenation and perfusion measurements in cortex and medulla.

Acta Physiol (Oxf) 2019 09 21;227(1):e13292. Epub 2019 May 21.

Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Copenhagen University Hospital, Glostrup, Denmark.

Aim: Disturbances of renal medullary perfusion and metabolism have been implicated in the pathogenesis of kidney disease and hypertension. Furosemide, a loop diuretic, is widely used to prevent renal medullary hypoxia in acute kidney disease by uncoupling sodium metabolism, but its effects on medullary perfusion in humans are unknown. We performed quantitative imaging of both renal perfusion and oxygenation using Magnetic Resonance Imaging (MRI) before and during furosemide. Based on the literature, we hypothesized that furosemide would increase medullary oxygenation, decrease medullary perfusion, but cause minor changes (<10%) in renal artery flow (RAF).

Methods: Interleaved measurements of RAF, oxygenation (T *) and perfusion by arterial spin labelling in the renal cortex and medulla of 9 healthy subjects were acquired before and after an injection of 20 mg furosemide. They were preceded by measurements made during isometric exercise (5 minutes handgrip bouts), which are known to induce changes in renal hemodynamics, that served as a control for the sensitivity of the hemodynamic MRI measurements. Experiments were repeated on a second day to establish that the measurements and the induced changes were reproducible.

Results: After furosemide, T * values in the medulla increased by 53% (P < 0.01) while RAF and perfusion remained constant. After hand-grip exercise, T * values in renal medulla increased by 22% ± 9% despite a drop in medullary perfusion of 7.2% ± 4.7% and a decrease in renal arterial flow of 17.5% ± 1.7% (P < 0.05). Mean coefficients of variation between repeated measurements for all parameters were 7%.

Conclusion: Furosemide induced the anticipated increase in renal medullary oxygenation, attributable exclusively to a decrease in renal oxygen consumption, since no change of RAF, cortical or medullary perfusion could be demonstrated. All measures and the induced changes were reproducible.
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http://dx.doi.org/10.1111/apha.13292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6767552PMC
September 2019

The spectrum of cluster headache: A case report of 4600 attacks.

Cephalalgia 2019 Aug 26;39(9):1134-1142. Epub 2019 Mar 26.

1 Danish Headache Center, Department of Neurology, Rigshospitalet Glostrup, Glostrup, Denmark.

Introduction: Knowledge of the clinical features of cluster headache is mainly based on retrospective and cross-sectional studies. Here, we present a case of a chronic cluster headache patient who prospectively recorded timing and clinical features of all attacks for 6 years, aiming to describe the clinical spectrum and timing of cluster headache symptoms experienced and to identify daily and/or seasonal rhythmicity.

Methods: Registration of attack timing, duration, associated symptoms and severity was done prospectively on a smartphone application. Pain severity was recorded on a 0-10 scale. Attacks were divided into mild, moderate, severe, and very severe. We analysed diurnal rhythmicity by multimodal Gaussian analysis and spectral analysis.

Results: In total, 4600 attacks were registered (mean duration 39.3 (SD 18.5) min. Mean severity 3.6 (SD 1.28)). Mild attacks accounted for 14.2%, moderate 65.7%, severe 16.9% and very severe 3.2% of all attacks. Nocturnal attacks were more severe than daytime attacks. The number of autonomic symptoms and duration of attacks increased with pain severity. Peak chronorisk (risk of attacks occurring according to hour of day) was at 12.48 in the registration period. Over time, circadian rhythmicity and attack frequency varied.

Conclusion: Clinical characteristics of cluster headache attacks can vary greatly within the individual patient. Clinicians attempting to personalise the administration of preventive treatment should pay notice to the variation over time in diurnal rhythmicity. The recorded self-limiting mild attacks that do not fulfill the ICHD-3 criteria for a cluster headache attack warrant further investigation, as they could hold important information about disease activity.
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http://dx.doi.org/10.1177/0333102419833081DOI Listing
August 2019

Kinetic [18F]-Fluoride of the Knee in Normal Volunteers.

Clin Nucl Med 2019 May;44(5):377-385

Department of Radiology, Stanford University, Stanford, CA.

Purpose: [F]-sodium fluoride ([F]NaF) is a well-established bone-seeking agent that has shown promise to assess bone turnover in a variety of disorders, but its distribution in healthy knee joints has not been explored. This study aimed to investigate parametric values for [F]NaF uptake in various bone tissues types of the knee and their spatial distributions.

Methods: Twelve healthy subjects were hand-injected with 92.5 MBq of [F]NaF and scanned on a 3-T PET/MRI system. Listmode PET data for both knees were acquired for 50 minutes from injection simultaneously with MRI Dixon and angiography data. The image-derived input function was determined from the popliteal artery. Using the Hawkins model, Patlak analysis was performed to obtain Ki (Ki) values and nonlinear regression analysis to obtain Ki, K1, k3/(k2 + k3), and blood volume. Comparisons for the measured kinetic parameters, SUV, and SUVmax were made between tissue types (subchondral, cortical, and trabecular bone) and between regional subsections of subchondral bone.

Results: Cortical bone had the highest [F]NaF uptake differing significantly in all measured parameters when compared with trabecular bone and significantly higher SUVmax and K1 than subchondral bone. Subchondral bone also had significantly higher SUV, SUVmax, and Ki than trabecular bone tissue. Regional differences were observed in K1 and k3/(k2 + k3) values.

Conclusions: Quantitative [F]NaF PET is sensitive to variations in bone vascularization and metabolism in the knee joint.
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http://dx.doi.org/10.1097/RLU.0000000000002533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449188PMC
May 2019

Authors' Reply.

J Am Soc Nephrol 2019 04 13;30(4):711. Epub 2019 Feb 13.

Department of Nuclear Medicine, Physiology and PET, Rigshospitalet, Glostrup, Denmark.

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http://dx.doi.org/10.1681/ASN.2019010049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6442348PMC
April 2019

Assessment of Perfusion and Oxygenation of the Human Renal Cortex and Medulla by Quantitative MRI during Handgrip Exercise.

J Am Soc Nephrol 2018 10 11;29(10):2510-2517. Epub 2018 Sep 11.

Department of Clinical Physiology, Nuclear Medicine and Positron Emission Tomography, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark; and

Background: Renal flow abnormalities are believed to play a central role in the pathogenesis of nephropathy and in primary and secondary hypertension, but are difficult to measure in humans. Handgrip exercise is known to reduce renal arterial flow (RAF) by means of increased renal sympathetic nerve activity.

Methods: To monitor medullary and cortical oxygenation under handgrip exercise-reduced perfusion, we used contrast- and radiation-free magnetic resonance imaging (MRI) to measure regional changes in renal perfusion and blood oxygenation in ten healthy normotensive individuals during handgrip exercise. We used phase-contrast MRI to measure RAF, arterial spin labeling to measure perfusion, and both changes in transverse relaxation time (T*) and dynamic blood oxygenation level-dependent imaging to measure blood oxygenation.

Results: Handgrip exercise induced a significant decrease in RAF. In the renal medulla, this was accompanied by an increase of oxygenation (reflected by an increase in T*) despite a significant drop in medullary perfusion; the renal cortex showed a significant decrease in both perfusion and oxygenation. We also found a significant correlation ( =0.8) between resting systolic BP and the decrease in RAF during handgrip exercise.

Conclusions: Renal MRI measurements in response to handgrip exercise were consistent with a sympathetically mediated decrease in RAF. In the renal medulla, oxygenation increased despite a reduction in perfusion, which we interpreted as the result of decreased GFR and a subsequently reduced reabsorptive workload. Our results further indicate that the renal flow response's sensitivity to sympathetic activation is correlated with resting BP, even within a normotensive range.
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http://dx.doi.org/10.1681/ASN.2018030272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6171273PMC
October 2018

Chronorisk in cluster headache: A tool for individualised therapy?

Cephalalgia 2018 12 10;38(14):2058-2067. Epub 2018 Apr 10.

2 Danish Headache Center, Department of Neurology, Rigshospitalet-Glostrup, University of Copenhagen, Copenhagen, Denmark.

Background: The mechanisms behind the severe pain of cluster headache remain enigmatic. A distinguishing feature of the attacks is the striking rhythms with which they occur. We investigated whether statistical modelling can be used to describe 24-hour attack distributions and identify differences between subgroups.

Methods: Common hours of attacks for 351 cluster headache patients were collected. Probability distributions of attacks throughout the day (chronorisk) was calculated. These 24-hour distributions were analysed with a multimodal Gaussian fit identifying periods of elevated attack risk and a spectral analysis identifying oscillations in risk.

Results: The Gaussian model fit for the chronorisk distribution for all patients reporting diurnal rhythmicity (n = 286) had a goodness of fit R value of 0.97 and identified three times of increased risk peaking at 21:41, 02:02 and 06:23 hours. In subgroups, three to five modes of increased risk were found and goodness of fit values ranged from 0.85-0.99. Spectral analysis revealed multiple distinct oscillation frequencies in chronorisk in subgroups including a dominant circadian oscillation in episodic patients and an ultradian in chronic.

Conclusions: Chronorisk in cluster headache can be characterised as a sum of individual, timed events of increased risk, each having a Gaussian distribution. In episodic cluster headache, attacks follow a circadian rhythmicity whereas, in the chronic variant, ultradian oscillations are dominant reflecting a loss of association with sleep and perhaps explaining observed differences in the effects of specific treatments. The results demonstrate the ability to accurately model chronobiological patterns in a primary headache.
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http://dx.doi.org/10.1177/0333102418769955DOI Listing
December 2018

Chronobiology differs between men and women with cluster headache, clinical phenotype does not.

Neurology 2017 Mar 15;88(11):1069-1076. Epub 2017 Feb 15.

From the Danish Headache Center, Department of Neurology (N.L., A.P., R.J.), and Department of Clinical Physiology, Nuclear Medicine and PET (M.B., B.H.), Rigshospitalet-Glostrup, University of Copenhagen, Denmark.

Objective: To describe differences between the sexes in the phenotype of cluster headache (CH) in a large, well-characterized clinical CH population.

Methods: Patients from the Danish CH survey aged 18-65 years, diagnosed with CH according to International Classification of Headache Disorders, second edition, completed questionnaires and structured interviews.

Results: A total of 351 patients with CH participated, with a male:female ratio of 2:1. The diurnal variation of attacks showed moments of peak prominence in men's attack cycle to be advanced by 1 hour compared to women's, despite no difference in self-reported bedtime or chronotype ( = 0.31). The onset of CH decreased with increasing age for both sexes. Diagnostic delay was numerically longer for men vs women (6.56 vs 5.50 years, = 0.21); however, more women had previously been misdiagnosed (61.1% vs 45.5%, < 0.01) and received the correct diagnosis at a tertiary headache center (38.8% vs 20.9%, < 0.001). Only minor sex differences in clinical characteristics were found but chronic CH was more prevalent in women compared to men (44.0% vs 31.9%, < 0.05).

Conclusions: Despite a similar clinical phenotype, diurnal attack cycle is advanced by 1 hour in men with CH compared to women. Rhythmicity is a defining characteristic of CH and these findings suggest differences in the hypothalamus' influence on attack occurrence between the sexes. In addition, women were more often misdiagnosed and diagnosis in the primary or secondary sector more often failed. Furthermore, women had chronic CH more frequently than men. A long diagnostic delay and frequent misdiagnosis emphasize the need for increased awareness of CH in both sexes.
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http://dx.doi.org/10.1212/WNL.0000000000003715DOI Listing
March 2017

Assessment of muscle function using hybrid PET/MRI: comparison of F-FDG PET and T2-weighted MRI for quantifying muscle activation in human subjects.

Eur J Nucl Med Mol Imaging 2017 Apr 8;44(4):704-711. Epub 2016 Sep 8.

Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet Glostrup, Copenhagen University Hospital, Ndr. Ringvej 57, DK2600, Glostrup, Denmark.

Purpose: The aim of this study was to determine the relationship between relative glucose uptake and MRI T changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans.

Methods: Ten young healthy recreationally active men (age 21 - 28 years) were injected with F-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with F-FDG PET/MRI and muscle groups were evaluated for increases in F-FDG uptake and MRI T values.

Results: A significant linear correlation between F-FDG uptake and changes in muscle T (R  = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between F-FDG uptake and changes in muscle T did not vary among subjects.

Conclusion: This is the first assessment of skeletal muscle activation using hybrid PET/MRI and the first study to demonstrate a high correlation between F-FDG uptake and changes in muscle T with physical exercise. Accordingly, it seems that changes in muscle T may be used as a surrogate marker for glucose uptake and lead to an improved insight into the metabolic changes that occur with muscle activation. Such knowledge may lead to improved treatment strategies in patients with neuromuscular pathologies such as stroke, spinal cord injuries and muscular dystrophies.
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http://dx.doi.org/10.1007/s00259-016-3507-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5323465PMC
April 2017

The effects of phosphatidic acid supplementation on strength, body composition, muscular endurance, power, agility, and vertical jump in resistance trained men.

J Int Soc Sports Nutr 2016 2;13:24. Epub 2016 Jun 2.

Max Muscle Sports Nutrition, 210 West Taft Avenue, Orange, CA 92865 USA ; University of Phoenix, San Diego Campus, 9645 Granite Ridge Drive, San Diego, CA 92123 USA.

Background: Phosphatidic acid (PA) is a lipid messenger that has been shown to increase muscle protein synthesis via signaling stimulation of the mammalian target of rapamycin (mTOR). MaxxTOR® (MT) is a supplement that contains PA as the main active ingredient but also contains other synergistic mTOR signaling substances including L-Leucine, Beta-Hydroxy-Beta-Methylbutyrate (HMB), and Vitamin D3.

Methods: Eighteen healthy strength-trained males were randomly assigned to a group that either consumed MT (n = 8, 22.0 +/- 2.5 years; 175.8 +/- 11.5 cm; 80.3 +/- 15.1 kg) or a placebo (PLA) (n = 10, 25.6 +/- 4.2 years; 174.8 +/- 9.0 cm; 88.6 +/- 16.6 kg) as part of a double-blind, placebo controlled pre/post experimental design. All participants volunteered to complete the three day per week resistance training protocol for the eight week study duration. To determine the effects of MT, participants were tested on one repetition maximum (1RM) leg press strength (LP), 1RM bench press strength (BP), push-ups to failure (PU), vertical jump (VJ), pro-agility shuttle time (AG), peak power output (P), lean body mass (LBM), fat mass (FM), and thigh muscle mass (TMM). Subjects were placed and monitored on an isocaloric diet consisting of 25 protein, 50 carbohydrates, and 25 % fat by a registered dietitian. Separate two-way mixed factorial repeated measures ANOVA's (time [Pre, Post] x group [MT and PLA] were used to investigate strength, body composition, and other performance changes. Post-hoc tests were applied as appropriate. Analysis were performed via SPSS with significance at (p ≤ 0.05).

Results: There was a significant main effect (F(1,16) = 33.30, p < 0.001) for LBM where MT significantly increased LBM when compared to the PLA group (p < 0.001). Additionally, there was a significant main effect for LP (F(1,16) = 666.74, p < 0.001) and BP (F(1,16) = 126.36, p < 0.001) where both increased significantly more in MT than PLA group (p < 0.001). No significant differences between MT and PLA were noted for FM, TMM, VJ, AG, P, or PU.

Conclusion: The results of this eight week trial suggest that the addition of MaxxTOR® to a 3-day per week resistance training program can positively impact LBM and strength beyond the results found with exercise alone.
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http://dx.doi.org/10.1186/s12970-016-0135-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4891923PMC
February 2017

Evidence of a Christmas spirit network in the brain: functional MRI study.

BMJ 2015 Dec 16;351:h6266. Epub 2015 Dec 16.

Functional Imaging Unit and Department of Clinical Physiology, Nuclear Medicine and PET, Rigshopitalet, Glostrup, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark

Objective: To detect and localise the Christmas spirit in the human brain.

Design: Single blinded, cross cultural group study with functional magnetic resonance imaging (fMRI).

Setting: Functional imaging unit and department of clinical physiology, nuclear medicine and PET in Denmark.

Participants: 10 healthy people from the Copenhagen area who routinely celebrate Christmas and 10 healthy people living in the same area who have no Christmas traditions.

Main Outcome Measures: Brain activation unique to the group with Christmas traditions during visual stimulation with images with a Christmas theme.

Methods: Functional brain scans optimised for detection of the blood oxygen level dependent (BOLD) response were performed while participants viewed a series of images with Christmas themes interleaved with neutral images having similar characteristics but containing nothing that symbolises Christmas. After scanning, participants answered a questionnaire about their Christmas traditions and the associations they have with Christmas. Brain activation maps from scanning were analysed for Christmas related activation in the "Christmas" and "non-Christmas" groups individually. Subsequently, differences between the two groups were calculated to determine Christmas specific brain activation.

Results: Significant clusters of increased BOLD activation in the sensory motor cortex, the premotor and primary motor cortex, and the parietal lobule (inferior and superior) were found in scans of people who celebrate Christmas with positive associations compared with scans in a group having no Christmas traditions and neutral associations. These cerebral areas have been associated with spirituality, somatic senses, and recognition of facial emotion among many other functions.

Conclusions: There is a "Christmas spirit network" in the human brain comprising several cortical areas. This network had a significantly higher activation in a people who celebrate Christmas with positive associations as opposed to a people who have no Christmas traditions and neutral associations. Further research is necessary to understand this and other potential holiday circuits in the brain. Although merry and intriguing, these findings should be interpreted with caution.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4681765PMC
http://dx.doi.org/10.1136/bmj.h6266DOI Listing
December 2015

Measurement of brain oxygenation changes using dynamic T(1)-weighted imaging.

Neuroimage 2013 Sep 8;78:7-15. Epub 2013 Apr 8.

Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital, Glostrup Hospital, 57 Ndr. Ringvej, DK-2600 Glostrup, Denmark.

Magnetic resonance imaging (MRI) has proven useful in evaluating oxygenation in several types of tissue and blood. This study evaluates brain tissue oxygenation changes between normoxia and hyperoxia in healthy subjects using dynamic T1 and T2*-weighted imaging sequences. The change in FiO2 induced by hyperoxia caused a significant decrease in T1. A model to determine changes in tissue oxygen tension from the T1-weighted MRI signal is presented based on previous findings that T1 is sensitive to oxygen tension whereas T2* is sensitive to blood saturation. The two sequences produce results with different regional and temporal dynamics. These differences combined with results from simulations of the T1 signal intensities, indicate an increase in extravascular oxygen tension during hyperoxia. This study concludes that T1 and T2* responses to FiO2 serve as independent biomarkers of oxygen physiology in the brain with a potential to provide quantitative information on tissue oxygenation.
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http://dx.doi.org/10.1016/j.neuroimage.2013.03.068DOI Listing
September 2013

Fitness Assessment Comparison Between the "Jackie Chan Action Run" Videogame, 1-Mile Run/Walk, and the PACER.

Games Health J 2012 Jun 27;1(3):223-7. Epub 2012 Apr 27.

1 Department of Kinesiology, California State University , San Bernardino, San Bernardino, California.

Objective: The purpose of this study was to examine whether a correlation existed among the scores of the "Jackie Chan Studio Fitness(™) Action Run" active videogame (XaviX(®), SSD Company, Ltd., Kusatsu, Japan), the 1-mile run/walk, and Progressive Aerobic Cardiovascular Endurance Run (PACER) aerobic fitness tests of the FITNESSGRAM(®) (The Cooper Institute, Dallas, TX) in order to provide a potential alternative testing method for days that are not environmentally desirable for outdoor testing.

Subjects And Methods: Participants were a convenience sample from physical education classes of students between the ages of 10 and 15 years. Participants (n=108) were randomly assigned to one of three groups with the only difference being the order of testing. The tests included the "Jackie Chan Action Run" active videogame, the 1-mile run/walk, and the PACER. Testing occurred on three different days during the physical education class. Rating of perceived exertion (RPE) was reported.

Results: Significant correlations (r=-0.598 to 0.312) were found among the three aerobic fitness tests administered (P<0.05). The RPE for the "Jackie Chan Action Run" was lower than the RPE for the 1-mile run/walk and the PACER (3.81±1.89, 5.93±1.77, and 5.71±2.14, respectively).

Conclusions: The results suggest that the "Jackie Chan Action Run" test could be an alternative to the 1-mile run/walk and PACER, allowing physical education teachers to perform aerobic fitness testing in an indoor setting that requires less space. Also, children may be more willing to participate in the "Jackie Chan Action Run" based on the lower RPE.
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http://dx.doi.org/10.1089/g4h.2012.0007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5816347PMC
June 2012

Energy expenditure comparison between walking and running in average fitness individuals.

J Strength Cond Res 2012 Apr;26(4):1039-44

Department of Kinesiology, Human Performance Laboratory, California State University, San Bernardino, California, USA.

Increased energy expenditure (EE) is a key component in maintaining a healthy body mass. Walking and running are 2 common aerobic activities that increase EE above resting values. The purpose of this study was to compare the EE of individuals with average fitness during a walk and run for 1600 meters at 86 m·min(-1) and 160 m·min(-1), respectively. In addition, EE after the walk and run was compared. Fifteen females and 15 males (21.90 ± 2.52 y; 168.89 ± 11.20 cm; 71.01 ± 17.30 kg; 41.51 ± 6.31 ml(-1)·kg(-1)·min(-1)) volunteered to participate. Each participant completed a VO2max test. In addition, oxygen consumption was measured at rest for 10 minutes before exercise, during the walk and run, and after the walk and run for 30 minutes of recovery. EE during exercise was 372.54 ± 78.16 kilojoules for the walk and 471.03 ± 100.67 kilojoules for the run. Total EE including excess postexercise EE was 463.34 ± 80.38 kilojoules and 664.00 ± 149.66 kilojoules for the walk and run, respectively. Postexercise EE returned to resting values 10 minutes after the walk and 15 minutes after the run. Walking and running are both acceptable activities that increase EE above rest and can be performed without the expense of a health club membership and meet adequate kilojoule expenditure according to American College of Sports Medicine guidelines.
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http://dx.doi.org/10.1519/JSC.0b013e31822e592cDOI Listing
April 2012

MEASUREMENT OF ENERGY EXPENDITURE WHILE PLAYING EXERGAMES AT A SELF-SELECTED INTENSITY.

Open Sports Sci J 2012 2;5:1-6. Epub 2012 Sep 2.

California State University, San Bernardino.

Exergames have been suggested as a possible alternative to traditional exercise in the general population. The purpose of this study was to examine the heart rate (HR) and energy expenditure (EE) of young adults playing several different exergames, while self-selecting the component of the game to play and the intensity. A total of 117 participants, 18-35 years of age, were evaluated on one of four active video games. Participants were free to choose any component of the given game to play and they played at a self-selected intensity. The average HR and EE during the individual games were compared to resting conditions and to the American College of Sports Medicine (ACSM) guidelines. The HR and EE increased above resting conditions during each game (p<0.05). When the results of all games were combined, the HR was 125.4 ± 20.0 bpm and the average EE was 6.7 ± 2.1 kcal/min. This HR represents an average percent of heart rate reserve of 44.6 ± 14.1, high enough to be considered moderate intensity exercise. If performed for 30 minutes a day, five days per week, the average EE would be 1,005 kcals, enough to meet the ACSM recommendations for weekly EE. Therefore, at least some exergames could be a component of an exercise program.
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http://dx.doi.org/10.2174/1875399X01205010001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5773087PMC
September 2012

Health-related variables and functional fitness among older adults.

Int J Aging Hum Dev 2010 ;70(2):107-18

California State University, San Bernardino, CA 92407, USA.

This study assesses the functional fitness of a convenient sample of older adults (>70 years), to examine correlations between functional fitness and several other health-related variables and to compare with criterion performance data as established by Rikli and Jones (2001). One hundred and seven community-dwelling older adults with an average age of 78.36 +/- 5.60 years performed the Senior Fitness Test (SFT) and responded to several health-related questionnaires. The SFT scores were similar to the scores in the low-active group data published by Rikli and Jones (1999b). There was a strong correlation between the 30-second arm curl and the 2-minute step-in-place (r = .54, p < .01). More than one-half of the participants performed in the normal range or above normal range, according to the criterion performance data. This demonstrates a high level of functional fitness.
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http://dx.doi.org/10.2190/AG.70.2.aDOI Listing
May 2010

Racial/Ethnic Differences in Bone Mineral Density of Young Adults.

Int J Exerc Sci 2010;3(4):197-205. Epub 2010 Oct 15.

Human Performance Laboratory; Department of Kinesiology; California State University, San Bernardino; San Bernardino, California, USA.

An estimated 1.5 million people suffer a bone disease-related fracture every year. Most work investigating bone mineral density (BMD) focuses on post-menopausal females but a report from the Surgeon General in 2004 stated that of particular concern are men, racial and ethnic minorities, poor individuals, individuals with disabilities, and individuals living in rural areas. The purpose of this study was to examine the racial/ethnic differences in bone mineral density of young adults and to investigate any correlations with variables suggested to influence BMD. BMD was assessed at a younger age than most studies based on the assumption that osteoporosis is a pediatric disorder that manifests in old age. Whole-body BMD, percent body fat (BF), fat mass (FM), and lean mass (LM) of 103 college-aged Blacks, Whites, and Hispanics (18 - 34 years of age) were measured using a Lunar Prodigy Dual Energy X-ray Absorptiometry (DEXA). Blacks and Whites were taller than Hispanics. Blacks had higher BMD than Whites and Hispanics. Blacks and Whites had higher t-scores than Hispanics. Weight and LM correlated with BMD for all three groups. Height correlated with BMD for Blacks only. FM correlated with BMD for Hispanics only. In conclusion, BMD is suggested to be higher in Blacks than Whites and Hispanics. LM is suggested to be an important component of bone health. It is important to stress resistance training for building and maintaining bone health throughout life.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4738873PMC
October 2010

The Addition of a Video Game to Stationary Cycling: The Impact on Energy Expenditure in Overweight Children.

Open Sports Sci J 2009 Jan;2:42-46

Department of Kinesiology, California State University, San Bernardino.

INTRODUCTION: The prevalence of obesity in children has reached epidemic proportions with over 37% of children aged 6-11 years in the U.S. being classified as "at risk for overweight" or "overweight." Utilization of active video games has been proposed as one possible mechanism to help shift the tide of the obesity epidemic. PURPOSE: The purpose of this study was to determine if riding a stationary bike that controlled a video game would lead to significantly greater energy expenditure than riding the same bike without the video game connected. METHODS: Twenty children, 7-14 years old, with a BMI classification of "at risk for overweight" or "overweight" participated in this study. Following familiarization, energy expenditure was evaluated while riding a stationary bike for 20 minutes. One test was performed without the addition of a video game and one test with the bike controlling the speed of a car on the video game. RESULTS: Oxygen consumption and energy expenditure were significantly elevated above baseline in both conditions. Energy expenditure was significantly higher while riding the bike as it controlled the video game (4.4 ± 1.2 Kcal·min(-1)) than when riding the bike by itself (3.7 ± 1.1 Kcal·min(-1)) (p<0.05). Perceived exertion was not significantly different between the two sessions (p>0.05). CONCLUSION: Using a stationary bike to control a video game led to greater energy expenditure than riding a stationary bike without the video game and without a related increase in perceived exertion.
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http://dx.doi.org/10.2174/1875399X00902010042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2784676PMC
January 2009

Active Video Games and Energy Expenditure in Overweight Children.

Int J Fit 2008 Jul;4(2):17-23

California State University, San Bernardino, Department of Kinesiology (HP 120), 5500 University Parkway, San Bernardino, CA 92407, , , Email:

The prevalence of overweight in children has increased significantly in recent years. Frequent television viewing and the playing of video games have often been linked to the high prevalence of overweight. The purpose of this study was to determine if overweight children, given access to active video games, will play them at an intensity that will significantly increase energy expenditure. Twenty-three children, classified as "at risk for overweight" or "overweight," participated in this study. After a 10-minute baseline period in which the children watched a cartoon, the participants played the Jackie Chan Fitness Studio® (Xavix, Hong Kong) games for 30 minutes while rotating through the games as desired and resting whenever needed. Energy expenditure significantly increased from a mean at baseline of 1.15 ± 0.32 kcal/min to 4.08±1.18 kcal/min during the 30-minutes that the participants were given access to the games ( <.001). The total energy expenditure during the 30-minute time frame was 122.30 ± 35.40 kcal. The energy expenditure varied between individuals, with a low value of 75.00 kcal to a high of 205.86 kcal. Although a modest level of energy expenditure, this level of exertion could contribute to an overall weight control program in children.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3966474PMC
July 2008
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