Russell T Hepple

Russell T Hepple, Ph.D.

Professor

Department: HP-PHYSICAL THERAPY
Business Phone: (352) 294-8703
Business Email: rthepple@phhp.ufl.edu

Teaching Profile

Courses Taught
2019-2024
GMS6476 Fundamentals of Skeletal Muscle
2019-2021
RSD7979 Advanced Research
2020,2022-2024
RSD6401 Skeletal Muscle in Aging and Disease, and Implications for Rehabilitation
2018,2023-2024
RSD6910 Supervised Research
2018
GMS7593 Topics in Pharmacology and Toxicology
2018
GMS7979 Advanced Research
2018
RSD6930 Special Topics in Rehabilitation Science
2018,2021
PHT6152C Exercise Physiology
2021
GMS5905 Special Topics in Biomedical Sciences
2021,2023
GMS6622 Mitochondrial Biology in Aging and Disease
2022
RSD7980 Research for Doctoral Dissertation
2022-2024
PHT6153 Physiology for Pt
2022-2023
HSC4913 Supervised Research Experience

Research Profile

My primary research focus is on understanding the impact of age-related changes in skeletal muscle mass and contractile function in health and disease, the mechanisms contributing to these changes, and identification of therapeutic strategies for preserving muscle. Our initial research in this area established that impairments in skeletal muscle contribute to the reduced whole body exercise capacity seen with aging independent of a reduction in muscle oxygen delivery. Strikingly, we showed that long term reduction in energy intake (caloric restriction) could completely prevent the normal age-related decline in skeletal muscle function and provided the first indications that this likely occurred through maintained proteostatic mechanisms. In contrast, we showed that long term endurance training could not prevent the age-related decline in muscle mass and function, despite increasing mean lifespan and reducing age-related replacement fibrosis of the heart.

In evaluating the applicability of the mitochondrial theory of aging to aging of skeletal muscle, over the past several years we have been working towards identifying the nature, magnitude, and causes of mitochondrial dysfunction in striated muscle with aging, with the aim of understanding the therapeutic potential for targeting the mitochondrion. Our work has highlighted the importance of using analytical methods that preserve mitochondrial structure when addressing this question, and has revealed that persistent denervation, rather than mitochondrial dysfunction, is a primary cause of skeletal muscle atrophy and contractile dysfunction in advanced age. Interestingly, we also showed that some of the mitochondrial dysfunction seen in advanced age is secondary to the accumulation of persistently denervated muscle fibers in human skeletal muscle in advanced age. Further to this, we have established that the accelerating phase of muscle atrophy with aging is coincident with the accumulation of persistently denervated muscle fibers and a transcriptional and microRNA profile indicative of a failed reinnervation response.

In stark contrast to the declines seen with normal aging, in world class octogenarian athletes, who perform remarkable feats of athleticism at an age better known for impaired mobility and loss of independence, we have found that a primary explanation for their superior protection of muscle mass and function relates to an attenuated decline in the numbers of the smallest functional units of muscle, the motor units (=a motor neuron and the muscle fibers it innervates). Additional studies are showing that whereas mitochondrial function is not better preserved in these individuals, they exhibit several indices of superior reinnervation and neuroprotection relative to non-athlete but otherwise healthy octogenarians. As such, these results have highlighted the importance of preserving the motor unit rather than mitochondrial function in seeking strategies for attenuating the decline in skeletal muscle mass and function with aging.

Building upon this foundation knowledge in aging, we are now embarking on studies to understand mechanisms of skeletal muscle atrophy and contractile dysfunction in other settings such as chronic lung disease, cancer cachexia, and chemotherapy treatment.

Areas of Interest
  • Aging
  • Amyotrophic Lateral Sclerosis
  • Aryl hydrocarbon receptor
  • Cancer Cachexia
  • Mitochondria
  • Motor neuron
  • Motor unit
  • Muscle atrophy
  • Neuromuscular junction
  • Neuronal excitotoxicity
Open Researcher and Contributor ID (ORCID)

0000-0003-3640-486X

Publications

2024
Associations Between D3Cr Muscle Mass and Magnetic Resonance Thigh Muscle Volume With Strength, Power, Physical Performance, Fitness, and Limitations in Older Adults in the SOMMA Study
The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences. 79(4) [DOI] 10.1093/gerona/glae056.
2024
Associations of Skeletal Muscle Mass, Muscle Fat Infiltration, Mitochondrial Energetics, and Cardiorespiratory Fitness With Liver Fat Among Older Adults
The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences. 79(4) [DOI] 10.1093/gerona/glae047. [PMID] 38366047.
2024
Childhood adverse life events and skeletal muscle mitochondrial function
Science Advances. 10(10) [DOI] 10.1126/sciadv.adj6411. [PMID] 38446898.
2024
Chronic aryl hydrocarbon receptor activity impairs muscle mitochondrial function with tobacco smoking.
Journal of cachexia, sarcopenia and muscle. [DOI] 10.1002/jcsm.13439. [PMID] 38333944.
2024
Energetics and clinical factors for the time required to walk 400 m: The Study of Muscle, Mobility and Aging (SOMMA).
Journal of the American Geriatrics Society. [DOI] 10.1111/jgs.18763. [PMID] 38243364.
2024
Lower muscle mitochondrial energetics is associated with greater phenotypic frailty in older women and men: the Study of Muscle, Mobility and Aging.
GeroScience. 46(2):2409-2424 [DOI] 10.1007/s11357-023-01002-1. [PMID] 37987886.
2024
Nutrient Metabolites Associated With Low D3Cr Muscle Mass, Strength, and Physical Performance in Older Men
The Journals of Gerontology: Series A. 79(2) [DOI] 10.1093/gerona/glad217. [PMID] 37694554.
2024
Resting-state Functional Connectivity of the Motor and Cognitive Areas is Preserved in Masters Athletes
Neuroscience. 546:53-62 [DOI] 10.1016/j.neuroscience.2024.03.024.
2024
Role of Cardiorespiratory Fitness and Mitochondrial Oxidative Capacity in Reduced Walk Speed of Older Adults with Diabetes.
Diabetes. [DOI] 10.2337/db23-0827. [PMID] 38551899.
2024
Signatures of cysteine oxidation on muscle structural and contractile proteins are associated with physical performance and muscle function in older adults: Study of Muscle, Mobility and Aging (SOMMA)
Aging Cell. [DOI] 10.1111/acel.14094.
2024
Skeletal Muscle Energetics Explain the Sex Disparity in Mobility Impairment in the Study of Muscle, Mobility and Aging
The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences. 79(4) [DOI] 10.1093/gerona/glad283. [PMID] 38150179.
2024
Vigor to Frailty As a Continuum—A New Approach in the Study of Muscle, Mobility, and Aging Cohort
The Journals of Gerontology: Series A. 79(1) [DOI] 10.1093/gerona/glad244. [PMID] 37847228.
2023
Associations between D3Cr muscle mass and MR thigh muscle volume with strength, power, physical performance, fitness, and limitations in older adults in the SOMMA study.
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.09.23298303. [PMID] 37986809.
2023
Associations of Skeletal Muscle Mass, Muscle Fat Infiltration, Mitochondrial Energetics, and Cardiorespiratory Fitness with Liver Fat Among Older Adults.
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.10.24.23297480. [PMID] 37961367.
2023
Autophagy gene expression in skeletal muscle of older individuals is associated with physical performance, muscle volume and mitochondrial function in the Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.04.23297979. [PMID] 37961308.
2023
Childhood adverse life events and skeletal muscle mitochondrial function.
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.07.23298177. [PMID] 37986889.
2023
Energetics and Clinical Factors for the Time Required to Walk 400 Meters The Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.10.23298299. [PMID] 37986884.
2023
Expression of mitochondrial oxidative stress response genes in muscle is associated with mitochondrial respiration, physical performance, and muscle mass in the Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.05.23298108. [PMID] 37986804.
2023
Higher Expression of Denervation-responsive Genes is Negatively Associated with Muscle Volume and Performance Traits in the Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.04.23298090. [PMID] 37961531.
2023
Mitochondrial Energetics in Skeletal Muscle Are Associated With Leg Power and Cardiorespiratory Fitness in the Study of Muscle, Mobility and Aging
The Journals of Gerontology: Series A. 78(8):1367-1375 [DOI] 10.1093/gerona/glac238. [PMID] 36462195.
2023
Muscle mass, strength, power and physical performance and their association with quality of life in older adults, the Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.10.31.23297845. [PMID] 37961491.
2023
Muscle Steatosis and Fibrosis in Older Adults, From the AJR Special Series on Imaging of Fibrosis.
AJR. American journal of roentgenology. [DOI] 10.2214/AJR.23.29742. [PMID] 37610777.
2023
Role of Cardiorespiratory Fitness and Mitochondrial Energetics in Reduced Walk Speed of Older Adults with Diabetes in the Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.03.23297992. [PMID] 37986814.
2023
Signatures of Cysteine Oxidation on Muscle Structural and Contractile Proteins Are Associated with Physical Performance and Muscle Function in Older Adults: Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.07.23298224. [PMID] 37986748.
2023
Skeletal muscle energetics explain the sex disparity in mobility impairment in the Study of Muscle, Mobility and Aging (SOMMA).
medRxiv : the preprint server for health sciences. [DOI] 10.1101/2023.11.08.23298271. [PMID] 37987007.
2023
Skeletal Muscle Health, Physical Performance, and Lower Urinary Tract Symptoms in Older Adults: The Study of Muscle, Mobility, and Aging
The Journals of Gerontology: Series A. [DOI] 10.1093/gerona/glad218.
2023
The Study of Muscle, Mobility and Aging (SOMMA): A Unique Cohort Study About the Cellular Biology of Aging and Age-related Loss of Mobility
The Journals of Gerontology: Series A. 78(11):2083-2093 [DOI] 10.1093/gerona/glad052. [PMID] 36754371.
2022
Author response: Unbiased proteomics, histochemistry, and mitochondrial DNA copy number reveal better mitochondrial health in muscle of high-functioning octogenarians
. [DOI] 10.7554/elife.74335.sa2.
2022
Chronic aryl hydrocarbon receptor activity phenocopies smoking‐induced skeletal muscle impairment
Journal of Cachexia, Sarcopenia and Muscle. 13(1):589-604 [DOI] 10.1002/jcsm.12826. [PMID] 34725955.
2022
Integrating Mechanisms of Exacerbated Atrophy and Other Adverse Skeletal Muscle Impact in COPD.
Frontiers in physiology. 13 [DOI] 10.3389/fphys.2022.861617. [PMID] 35721564.
2022
NMR Spectroscopy Identifies Chemicals in Cigarette Smoke Condensate That Impair Skeletal Muscle Mitochondrial Function.
Toxics. 10(3) [DOI] 10.3390/toxics10030140. [PMID] 35324765.
2022
Unbiased proteomics, histochemistry, and mitochondrial DNA copy number reveal better mitochondrial health in muscle of high-functioning octogenarians
eLife. 11 [DOI] 10.7554/elife.74335.
2021
Impaired muscle mitochondrial energetics is associated with uremic metabolite accumulation in chronic kidney disease
JCI Insight. 6(1) [DOI] 10.1172/jci.insight.139826. [PMID] 33290279.
2021
Mitochondrial Permeability Transition Causes Mitochondrial Reactive Oxygen Species- and Caspase 3-Dependent Atrophy of Single Adult Mouse Skeletal Muscle Fibers.
Cells. 10(10) [DOI] 10.3390/cells10102586. [PMID] 34685566.
2021
Variation in muscle and neuromuscular junction morphology between atrophy-resistant and atrophy-prone muscles supports failed re-innervation in aging muscle atrophy.
Experimental gerontology. 156 [DOI] 10.1016/j.exger.2021.111613. [PMID] 34740815.
2020
Extreme variation in testes size in an insect is linked to recent mating activity.
Journal of evolutionary biology. 33(2):142-150 [DOI] 10.1111/jeb.13574. [PMID] 31765505.
2020
Mitochondrial Content, but Not Function, Is Altered With a Multimodal Resistance Training Protocol and Adequate Protein Intake in Leucine-Supplemented Pre/Frail Women.
Frontiers in nutrition. 7 [DOI] 10.3389/fnut.2020.619216. [PMID] 33553232.
2020
Mitochondrial Mechanisms of Neuromuscular Junction Degeneration with Aging
Cells. 9(1) [DOI] 10.3390/cells9010197. [PMID] 31941062.
2020
mtDNA Mutation Accumulation in Muscle Is Not a Major Cause of Fiber Loss. Reply to “Comment on: Mitochondrial Mechanisms of Neuromuscular Junction Degeneration with Aging. Cells 2020, 9, 197”
Cells. 9(8) [DOI] 10.3390/cells9081821. [PMID] 32752189.
2019
Colon 26 adenocarcinoma (C26)-induced cancer cachexia impairs skeletal muscle mitochondrial function and content.
Journal of muscle research and cell motility. 40(1):59-65 [DOI] 10.1007/s10974-019-09510-4. [PMID] 30945134.
2019
Commentaries on Viewpoint: Rejuvenation of the term sarcopenia.
Journal of applied physiology (Bethesda, Md. : 1985). 126(1):257-262 [DOI] 10.1152/japplphysiol.00816.2018. [PMID] 30694711.
2019
Fidelity of muscle fibre reinnervation modulates ageing muscle impact in elderly women
The Journal of Physiology. 597(19):5009-5023 [DOI] 10.1113/jp278261.
2019
Reduced Mitochondrial Content, Elevated Reactive Oxygen Species, and Modulation by Denervation in Skeletal Muscle of Prefrail or Frail Elderly Women
The Journals of Gerontology: Series A. 74(12):1887-1895 [DOI] 10.1093/gerona/glz066.
2018
Protective role of Parkin in skeletal muscle contractile and mitochondrial function
The Journal of Physiology. 596(13):2565-2579 [DOI] 10.1113/jp275604.
2018
Smoke‐induced neuromuscular junction degeneration precedes the fibre type shift and atrophy in chronic obstructive pulmonary disease
The Journal of Physiology. 596(14):2865-2881 [DOI] 10.1113/jp275558.
2018
When motor unit expansion in ageing muscle fails, atrophy ensues
The Journal of Physiology. 596(9):1545-1546 [DOI] 10.1113/jp275981.
2017
Eccentric Ergometer Training Promotes Locomotor Muscle Strength but Not Mitochondrial Adaptation in Patients with Severe Chronic Obstructive Pulmonary Disease.
Frontiers in physiology. 8 [DOI] 10.3389/fphys.2017.00114. [PMID] 28316572.
2017
High Aerobic Capacity Mitigates Changes in the Plasma Metabolomic Profile Associated with Aging.
Journal of proteome research. 16(2):798-805 [DOI] 10.1021/acs.jproteome.6b00796. [PMID] 27936752.
2017
Mitochondrial energy deficiency leads to hyperproliferation of skeletal muscle mitochondria and enhanced insulin sensitivity.
Proceedings of the National Academy of Sciences of the United States of America. 114(10):2705-2710 [DOI] 10.1073/pnas.1700997114. [PMID] 28223503.
2017
The impact of ageing, physical activity, and pre-frailty on skeletal muscle phenotype, mitochondrial content, and intramyocellular lipids in men.
Journal of cachexia, sarcopenia and muscle. 8(2):213-228 [DOI] 10.1002/jcsm.12139. [PMID] 27897402.
2016
Denervation drives mitochondrial dysfunction in skeletal muscle of octogenarians.
The Journal of physiology. 594(24):7361-7379 [DOI] 10.1113/JP272487. [PMID] 27619626.
2016
Editorial: Mitochondria in Skeletal Muscle Health, Aging and Diseases.
Frontiers in physiology. 7 [PMID] 27766080.
2016
Exercise Promotes Healthy Aging of Skeletal Muscle.
Cell metabolism. 23(6):1034-1047 [DOI] 10.1016/j.cmet.2016.05.007. [PMID] 27304505.
2016
Failed reinnervation in aging skeletal muscle.
Skeletal muscle. 6(1) [DOI] 10.1186/s13395-016-0101-y. [PMID] 27588166.
2016
Failed upregulation of TFAM protein and mitochondrial DNA in oxidatively deficient fibers of chronic obstructive pulmonary disease locomotor muscle.
Skeletal muscle. 6 [DOI] 10.1186/s13395-016-0083-9. [PMID] 26893822.
2016
Impact of aging on mitochondrial function in cardiac and skeletal muscle.
Free radical biology & medicine. 98:177-186 [DOI] 10.1016/j.freeradbiomed.2016.03.017. [PMID] 27033952.
2016
Innervation and neuromuscular control in ageing skeletal muscle.
The Journal of physiology. 594(8):1965-78 [DOI] 10.1113/JP270561. [PMID] 26437581.
2016
Motor unit number and transmission stability in octogenarian world class athletes: Can age-related deficits be outrun?
Journal of applied physiology (Bethesda, Md. : 1985). 121(4):1013-1020 [DOI] 10.1152/japplphysiol.00149.2016. [PMID] 27013605.
2016
Reduction in single muscle fiber rate of force development with aging is not attenuated in world class older masters athletes.
American journal of physiology. Cell physiology. 310(4):C318-27 [DOI] 10.1152/ajpcell.00289.2015. [PMID] 26632598.
2015
Anthracycline-containing chemotherapy causes long-term impairment of mitochondrial respiration and increased reactive oxygen species release in skeletal muscle.
Scientific reports. 5 [DOI] 10.1038/srep08717. [PMID] 25732599.
2015
Understanding the Cellular and Molecular Mechanisms of Physical Activity-Induced Health Benefits.
Cell metabolism. 22(1):4-11 [DOI] 10.1016/j.cmet.2015.05.011. [PMID] 26073496.
2014
Exercise training initiated in late middle age attenuates cardiac fibrosis and advanced glycation end-product accumulation in senescent rats.
Experimental gerontology. 50:9-18 [DOI] 10.1016/j.exger.2013.11.006. [PMID] 24280067.
2014
Fiber typing in aging muscle.
Exercise and sport sciences reviews. 42(2):45-52 [DOI] 10.1249/JES.0000000000000012. [PMID] 24508741.
2014
Increased sensitivity to mitochondrial permeability transition and myonuclear translocation of endonuclease G in atrophied muscle of physically active older humans.
FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 28(4):1621-33 [DOI] 10.1096/fj.13-242750. [PMID] 24371120.
2014
Mitochondrial involvement and impact in aging skeletal muscle.
Frontiers in aging neuroscience. 6 [DOI] 10.3389/fnagi.2014.00211. [PMID] 25309422.
2014
The relationship between muscle fiber type-specific PGC-1α content and mitochondrial content varies between rodent models and humans.
PloS one. 9(8) [DOI] 10.1371/journal.pone.0103044. [PMID] 25121500.
2013
Autophagic flux and oxidative capacity of skeletal muscles during acute starvation.
Autophagy. 9(10):1604-20 [DOI] 10.4161/auto.25955. [PMID] 23955121.
2013
Enhanced cardiac protein glycosylation (O-GlcNAc) of selected mitochondrial proteins in rats artificially selected for low running capacity.
Physiological genomics. 45(1):17-25 [DOI] 10.1152/physiolgenomics.00111.2012. [PMID] 23132757.
2013
Facts and controversies in our understanding of how caloric restriction impacts the mitochondrion.
Experimental gerontology. 48(10):1075-84 [DOI] 10.1016/j.exger.2013.03.004. [PMID] 23523973.
2013
Role of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) in denervation-induced atrophy in aged muscle: facts and hypotheses.
Longevity & healthspan. 2(1) [DOI] 10.1186/2046-2395-2-13. [PMID] 24472348.
2012
Denervation causes fiber atrophy and myosin heavy chain co-expression in senescent skeletal muscle.
PloS one. 7(1) [DOI] 10.1371/journal.pone.0029082. [PMID] 22235261.
2012
Last Word on Viewpoint: Muscle atrophy is not always sarcopenia.
Journal of applied physiology (Bethesda, Md. : 1985). 113(4) [DOI] 10.1152/japplphysiol.00682.2012. [PMID] 22896681.
2012
Mitochondrial function in permeabilized cardiomyocytes is largely preserved in the senescent rat myocardium.
PloS one. 7(8) [DOI] 10.1371/journal.pone.0043003. [PMID] 22912774.
2012
Mitochondrial functional specialization in glycolytic and oxidative muscle fibers: tailoring the organelle for optimal function.
American journal of physiology. Cell physiology. 302(4):C629-41 [DOI] 10.1152/ajpcell.00368.2011. [PMID] 22031602.
2012
Muscle atrophy is not always sarcopenia.
Journal of applied physiology (Bethesda, Md. : 1985). 113(4):677-9 [DOI] 10.1152/japplphysiol.00304.2012. [PMID] 22518833.
2012
Severe atrophy of slow myofibers in aging muscle is concealed by myosin heavy chain co-expression.
Experimental gerontology. 47(12):913-8 [DOI] 10.1016/j.exger.2012.07.013. [PMID] 22884852.
2011
Accumulation of severely atrophic myofibers marks the acceleration of sarcopenia in slow and fast twitch muscles.
Experimental gerontology. 46(8):660-9 [DOI] 10.1016/j.exger.2011.03.005. [PMID] 21513786.
2011
Adaptations in capillarization and citrate synthase activity in response to endurance training in older and young men.
The journals of gerontology. Series A, Biological sciences and medical sciences. 66(9):957-64 [DOI] 10.1093/gerona/glr096. [PMID] 21715648.
2011
Alterations in intrinsic mitochondrial function with aging are fiber type-specific and do not explain differential atrophy between muscles.
Aging cell. 10(6):1047-55 [DOI] 10.1111/j.1474-9726.2011.00745.x. [PMID] 21933339.
2011
Cardiac calcium pump inactivation and nitrosylation in senescent rat myocardium are not attenuated by long-term treadmill training.
Experimental gerontology. 46(10):803-10 [DOI] 10.1016/j.exger.2011.06.005. [PMID] 21763413.
2011
Lower oxidative DNA damage despite greater ROS production in muscles from rats selectively bred for high running capacity.
American journal of physiology. Regulatory, integrative and comparative physiology. 300(3):R544-53 [DOI] 10.1152/ajpregu.00250.2010. [PMID] 21148474.
2011
Mitochondria: isolation, structure and function.
The Journal of physiology. 589(Pt 18):4413-21 [DOI] 10.1113/jphysiol.2011.212712. [PMID] 21708903.
2011
Mitochondrial structure and function are disrupted by standard isolation methods.
PloS one. 6(3) [DOI] 10.1371/journal.pone.0018317. [PMID] 21512578.
2010
Initiating exercise training in late middle age minimally protects muscle contractile function and increases myocyte oxidative damage in senescent rats.
Experimental gerontology. 45(11):856-67 [DOI] 10.1016/j.exger.2010.07.003. [PMID] 20643203.
2010
Initiating treadmill training in late middle age offers modest adaptations in Ca2+ handling but enhances oxidative damage in senescent rat skeletal muscle.
American journal of physiology. Regulatory, integrative and comparative physiology. 298(5):R1269-78 [DOI] 10.1152/ajpregu.00663.2009. [PMID] 20200131.
2010
Mitochondrial functional impairment with aging is exaggerated in isolated mitochondria compared to permeabilized myofibers.
Aging cell. 9(6):1032-46 [DOI] 10.1111/j.1474-9726.2010.00628.x. [PMID] 20849523.
2010
Mitochondrial protein import in aging muscle: can Tom still do it? Focus on “Biogenesis of the mitochondrial Tom40 channel in skeletal muscle from aged animals and its adaptability to chronic contractile activity”.
American journal of physiology. Cell physiology. 298(6):C1298-300 [DOI] 10.1152/ajpcell.00070.2010. [PMID] 20219952.
2010
Slow twitch soleus muscle is not protected from sarcopenia in senescent rats.
Experimental gerontology. 45(9):662-70 [DOI] 10.1016/j.exger.2010.04.001. [PMID] 20398745.
2010
The O2 cost of the tension-time integral in isolated single myocytes during fatigue.
American journal of physiology. Regulatory, integrative and comparative physiology. 298(4):R983-8 [DOI] 10.1152/ajpregu.00715.2009. [PMID] 20130224.
2009
Anatomic capillarization is elevated in the medial gastrocnemius muscle of mighty mini mice.
Journal of applied physiology (Bethesda, Md. : 1985). 106(5):1660-7 [DOI] 10.1152/japplphysiol.91233.2008. [PMID] 19286572.
2009
Exercise training from late middle age until senescence does not attenuate the declines in skeletal muscle aerobic function.
American journal of physiology. Regulatory, integrative and comparative physiology. 297(3):R744-55 [DOI] 10.1152/ajpregu.90959.2008. [PMID] 19571205.
2009
Why eating less keeps mitochondria working in aged skeletal muscle.
Exercise and sport sciences reviews. 37(1):23-8 [DOI] 10.1097/JES.0b013e3181877dc5. [PMID] 19098521.
2008
Caloric restriction optimizes the proteasome pathway with aging in rat plantaris muscle: implications for sarcopenia.
American journal of physiology. Regulatory, integrative and comparative physiology. 295(4):R1231-7 [DOI] 10.1152/ajpregu.90478.2008. [PMID] 18703409.
2008
Determinants of VO2 max decline with aging: an integrated perspective.
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 33(1):130-40 [DOI] 10.1139/H07-174. [PMID] 18347663.
2008
Effects of aging and caloric restriction on bone structure and mechanical properties.
The journals of gerontology. Series A, Biological sciences and medical sciences. 63(11):1131-6 [PMID] 19038827.
2008
Exercise training in late middle-aged male Fischer 344 x Brown Norway F1-hybrid rats improves skeletal muscle aerobic function.
Experimental physiology. 93(7):863-71 [DOI] 10.1113/expphysiol.2008.042069. [PMID] 18356556.
2007
Differential sensitivities of cerebral and brachial blood flow to hypercapnia in humans.
Journal of applied physiology (Bethesda, Md. : 1985). 102(1):87-93 [PMID] 17023571.
2006
Caloric restriction protects mitochondrial function with aging in skeletal and cardiac muscles.
Rejuvenation research. 9(2):219-22 [PMID] 16706647.
2006
Dividing to keep muscle together: the role of satellite cells in aging skeletal muscle.
Science of aging knowledge environment : SAGE KE. 2006(3) [PMID] 16421381.
2006
Elevated caspase and AIF gene expression correlate with progression of sarcopenia during aging in male F344BN rats.
Experimental gerontology. 41(11):1149-56 [PMID] 17029665.
2006
Nitric oxide synthase inhibition reduces O2 cost of force development and spares high-energy phosphates following contractions in pump-perfused rat hindlimb muscles.
Experimental physiology. 91(3):581-9 [PMID] 16469818.
2006
No decline in skeletal muscle oxidative capacity with aging in long-term calorically restricted rats: effects are independent of mitochondrial DNA integrity.
The journals of gerontology. Series A, Biological sciences and medical sciences. 61(7):675-84 [PMID] 16870628.
2005
Long-term caloric restriction abrogates the age-related decline in skeletal muscle aerobic function.
FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 19(10):1320-2 [PMID] 15955841.
2005
Nitric oxide synthase inhibition reduces the O2 cost of force development in rat hindlimb muscles pump perfused at matched convective O2 delivery.
Experimental physiology. 90(6):889-900 [PMID] 16123049.
2005
The versatility of the pump-perfused rat hindlimb preparation: examples relating to skeletal muscle function and energy metabolism.
Canadian journal of applied physiology = Revue canadienne de physiologie appliquee. 30(5):576-90 [PMID] 16293905.
2004
Anatomic capillarization is maintained in relative excess of fiber oxidative capacity in some skeletal muscles of late middle-aged rats.
Journal of applied physiology (Bethesda, Md. : 1985). 96(6):2257-64 [PMID] 14966023.
2004
Fiber atrophy and hypertrophy in skeletal muscles of late middle-aged Fischer 344 x Brown Norway F1-hybrid rats.
The journals of gerontology. Series A, Biological sciences and medical sciences. 59(2):108-17 [PMID] 14999023.
2004
Skeletal muscle aging in F344BN F1-hybrid rats: I. Mitochondrial dysfunction contributes to the age-associated reduction in VO2max.
The journals of gerontology. Series A, Biological sciences and medical sciences. 59(11):1099-110 [PMID] 15602055.
2004
Skeletal muscle aging in F344BN F1-hybrid rats: II. Improved contractile economy in senescence helps compensate for reduced ATP-generating capacity.
The journals of gerontology. Series A, Biological sciences and medical sciences. 59(11):1111-9 [PMID] 15602056.
2003
No effect of trans sodium crocetinate on maximal O(2) conductance or V(O(2),max) in moderate hypoxia.
Respiratory physiology & neurobiology. 134(3):239-46 [PMID] 12660103.
2003
Sarcopenia–a critical perspective.
Science of aging knowledge environment : SAGE KE. 2003(46) [PMID] 14627844.
2003
Selected contribution: Bone adaptation with aging and long-term caloric restriction in Fischer 344 x Brown-Norway F1-hybrid rats.
Journal of applied physiology (Bethesda, Md. : 1985). 95(4):1739-45 [PMID] 12807893.
2003
V(O2) max is unaffected by altering the temporal pattern of stimulation frequency in rat hindlimb in situ.
Journal of applied physiology (Bethesda, Md. : 1985). 95(2):705-11 [PMID] 12704088.
2002
Muscle structural capacity for oxygen flux from capillary to fiber mitochondria.
Exercise and sport sciences reviews. 30(2):80-4 [PMID] 11991542.
2002
The role of O2 supply in muscle fatigue.
Canadian journal of applied physiology = Revue canadienne de physiologie appliquee. 27(1):56-69 [PMID] 11880691.
2001
Estimating the size of the capillary-to-fiber interface in skeletal muscle: a comparison of methods.
Journal of applied physiology (Bethesda, Md. : 1985). 91(5):2150-6 [PMID] 11641356.
2000
Skeletal muscle: master or slave of the cardiovascular system?
Medicine and science in sports and exercise. 32(1):89-93 [PMID] 10647534.
2000
Skeletal muscle: microcirculatory adaptation to metabolic demand.
Medicine and science in sports and exercise. 32(1):117-23 [PMID] 10647538.
2000
Structural basis of muscle O(2) diffusing capacity: evidence from muscle function in situ.
Journal of applied physiology (Bethesda, Md. : 1985). 88(2):560-6 [PMID] 10658023.
1999
Dissociation of peak vascular conductance and V(O2) max among highly trained athletes.
Journal of applied physiology (Bethesda, Md. : 1985). 87(4):1368-72 [PMID] 10517765.
1999
Oxygen uptake kinetics during exercise in chronic heart failure: influence of peripheral vascular reserve.
Clinical science (London, England : 1979). 97(5):569-77 [PMID] 10545307.
1999
Rapid force recovery in contracting skeletal muscle after brief ischemia is dependent on O(2) availability.
Journal of applied physiology (Bethesda, Md. : 1985). 87(6):2225-9 [PMID] 10601171.
1998
Increased capillarity in leg muscle of finches living at altitude.
Journal of applied physiology (Bethesda, Md. : 1985). 85(5):1871-6 [PMID] 9804593.
1997
A new measurement of tissue capillarity: the capillary-to-fibre perimeter exchange index.
Canadian journal of applied physiology = Revue canadienne de physiologie appliquee. 22(1):11-22 [PMID] 9018404.
1997
Quantitating the capillary supply and the response to resistance training in older men.
Pflugers Archiv : European journal of physiology. 433(3):238-44 [PMID] 9064638.
1997
Resistance and aerobic training in older men: effects on VO2peak and the capillary supply to skeletal muscle.
Journal of applied physiology (Bethesda, Md. : 1985). 82(4):1305-10 [PMID] 9104869.

Grants

May 2022 ACTIVE
Linking kynurenine accumulation and the AHR pathway to exacerbated aging
Role: Principal Investigator
Funding: NATL INST OF HLTH NIA
Aug 2021 ACTIVE
Mitochondrial Permeability Transition in Aging Muscle
Role: Principal Investigator
Funding: NATL INST OF HLTH NIA
Apr 2021 – Dec 2022
Relevance of Mitochondrial Permeability Transition in Tobacco-Smoke Toxicity in Skeletal Muscle
Role: Other
Funding: AMER HEART ASSOCIATION
Jul 2020 – Jul 2022
A New Understanding of Muscle Atrophy in Neuromuscular Disease
Role: Principal Investigator
Funding: UF RESEARCH
Jun 2020 – Nov 2023
Role of the aryl hydrocarbon receptor in tobacco smoke-induced skeletal muscle atrophy
Role: Co-Project Director/Principal Investigator
Funding: FL DEPT OF HLTH BIOMED RES PGM/J&E KING
Dec 2019 ACTIVE
Molecular Mechanisms regulating peripheral arterial disease pathobiology in chronic kidney disease
Role: Co-Investigator
Funding: NATL INST OF HLTH NHLBI
Jun 2019 – Oct 2021
OR-DRPD-ROF2019: Mechanisms of muscle dysfunction in chronic kidney disease
Role: Co-Investigator
Funding: UF RESEARCH
Jan 2019 – Jun 2022
Characterization of the transcriptome of very small angular fibers in aging muscle as a means of exposing potential mechanisms that are involved in causing their atrophy
Role: Principal Investigator
Funding: SUTTER HEALTH CALIFORNIA PACIFIC MED CTR
Jan 2019 – Jan 2019
Characterization of the transcriptome of very small angular fibers in aging muscle as a means of exposing potential mechanisms that are involved in causing their atrophy
Role: Principal Investigator
Funding: SUTTER HEALTH CALIFORNIA PACIFIC MED CTR
Jun 2018 ACTIVE
Study of muscle, mobility, and aging (SOMMA)
Role: Principal Investigator
Funding: SUTTER HEALTH CALIFORNIA PACIFIC MED CTR via NATL INST OF HLTH NIA
Jan 2017 – Mar 2019
Mechanisms of motor unit protection by exercise training in aging muscle
Role: Principal Investigator
Funding: RES INST OF THE MCGILL UNIV HLTH CNTR via CANADIAN INST OF HLTH RES

Education

Postdoc – Physiology
1999 · University of California San Diego, La Jolla, CA USA
PhD – Physiology
1996 · University of Toronto, CAN
MSc -Physiology
1991 · University of Toronto, CAN
BSc -Physiology
1988 · University of Saskatchewan, CAN

Contact Details

Phones:
Business:
(352) 294-8703
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1225 CENTER DR RM J397
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