Dr. Walter Frontera

Professor
Dr. Walter Frontera

Contact Info

  • Office A-692, Lab A-658

    School of Medicine
    University of Puerto Rico
    Medical Sciences Campus
    P.O. Box 365067
    San Juan, PR 00936-5067

  • (787) 758-2525 ext. 2133, 1392

Education

  • B.S. 1975, Biology, University of Puerto Rico, Rio Piedras, PR
  • M.D. 1979, Medicine, University of PR, School of Medicine, San Juan, PR
  • Postdoc 1979-80, Flexible Internship, University Hospital, UPR, School of Medicine, San Juan, PR
  • Postdoc 1980-83, Physical Medicine & Rehabilitation, University Hospital, UPR, School of Medicine, San Juan, PR
  • Ph.D. 1986, Applied (Exercise) Physiology, Boston University , Boston, MA

RESEARCH

We are interested in understanding the effect of various conditions or illnesses on the mechanical and physiological properties of single permeabilized skeletal muscle fibers. Specifically, we have studied the age-related alterations in those properties as well as the changes in muscle after injury to the spinal cord. Aging is associated with loss and dysfunction of skeletal muscle that is manifested at the level of single muscle fibers with a loss of muscle fiber size, maximal force, and specific force (muscle fiber quality). These changes translate into in vivo functional limitations that may be amenable to therapeutic interventions. Similarly, injury to the spinal cord is accompanied by a reduction in muscle fiber force and size and we are testing the possible beneficial effects of estrogen-based neuroprotection and potential to accelerate recovery of muscle function after medullary contusion.

GRANTS

RO1 AG046149-07A1, NIH/NIA
07/01/2020 to 06/30/2025
Building community Capacity for Disability Prevention for Minority Elders

2S21MD001830-04, NIH/NIMHD
08/01/2017-04/30/2026
Hispanics in Research Capability, School of Health Professions and School of Medicine Partnership (HIREC)

SC1GM144032-01, NIGMS/NIH
05/01/2022-04/30/2026
Effects of Tamoxifen in Skeletal Muscle Recovery after Spinal Cord Injury and Mechanisms Activated by

SELECTED PUBLICATIONS

Flores L, Frontera WR, Andrasik MP, del Río C, Mondriguez A, Price SA, Krantz EM, Pergan S, Silver J. Assessment of the inclusion of racial/ethnic minority, female, and older individuals in vaccine clinical trials. JAMA Netw Open 2021; 4(2): e2037640 (PMID: 33606033) 

• Gamboa JL, Roshanravan B, Townsend T, Keller CE, Falck A, Nian H, Yu C, Damon B, Frontera WR, Brown NJ, Alp Ikizler T. Mitochondrial dysfunction precedes initiation of maintenance hemodialysis in patients with chronic kidney disease. Clin J Amer Soc Nephrol 2020; 15:926-936 (PMID: 32591419)

• Lim J-Y, SeungJun C, Widrick, JJ, Phillips EM, Frontera WR. Passive force and viscoelastic properties single fibers in human aging muscles. Eur J Appl Physiol 2019; 119:2339-2348. (PMID: 31468173)

• Lee G, Lim J-Y, Frontera WR. Apoptosis in young and old denervated rat skeletal muscle. Muscle & Nerve 2017; 55:262-269. (PMID: 27312511)

• Rodríguez-Reyes N, Rodríguez-Zayas A, Javadov S, Frontera WR. Single muscle fiber contractile

properties in diabetic rat muscle. Muscle & Nerve 2016; 53:958-964. (PMID: 26598963)

• Makimura H, Stanley TL, Suresh C, DeSousa-Coelho AL, Frontera WR, Syu S, Braun L, Looby SE, Feldpausch MN, Torriani M, Lee H, Clish C, Patti ME, Grinspoon SK. Metabolic effects of long-term reduction in free fatty acids with acipimox in obesity: a randomized trial. J Clin Endo Met 2016; 101:1123-1133. (PMID: 26691888)

• Javadov S, Jang S, Rodriguez-Reyes N, Rodriguez-Zayas A, Soto J, Krainz T, Wipf P, Frontera WR. Mitochondria-targeted antioxidants preserves contractile properties and mitochondrial function of skeletal muscle in aged rats. Oncotarget (Aging) 2015; Sep 22 [Epub ahead of print] (PMID: 26415224)

• Hamarneh SR, Murphy CA, Shih CW, Frontera WR, Torriani M, Hodin R, Irazoqui JE, Makimura H. Relationship between Serum IGF-I and Skeletal Muscle IGF-I mRNA Expression to Phosphocreatine Recovery after exercise in Obese Men with Reduced GH. J Clin Endo Met 2015; 100:617-625. (PMID:25375982)

• Reid KF, Pasha E, Doros G, Clark DJ, Patten C, Phillips EM, Widrick J, Frontera WR, Fielding RA. Longitudinal decline of lower extremity muscle power in healthy and mobility-limited older adults: influence of muscle mass, strength, composition, neuromuscular activation and single fiber contractile properties. Eur J Appl Physiol 2014; 114:29-39 (PMID:24122149)

• Frontera WR, Ochala J. Skeletal muscle: a brief review of structure and function. Calcif Tissue Int 2014; 96:183-195 (PMID: 25294644).

• Choi SJ, Lim JY, Nibaldi EG, Phillips EM, Frontera WR, Fielding RA, Widrick JJ. Eccentric contraction induced injury to skinned muscle fibers of elderly adults. AGE 2012; 34:215-226. (PMID:21431924).

• Krivickas LS, Dorer DJ, Ochala J, Frontera WR. Relationship between force and size in human single muscle fibers. Exp Physiol 2011; 96.5:539-547.

• Bean JF, Kiely DK, LaRose S, O’Neill E, Goldstein R, Frontera WR. Increased velocity exercise specific to task (InVEST) training vs. the National Institute on Aging’s (NIA) strength training program: changes in limb power and mobility. J Gerontol A Med Sci 2009; 64A:983-991. (PMID: 19414509; PMC2720885)

• Frontera WR, Reid KF, Phillips EM, Krivickas LS, Hughes VA, Roubenoff R, Fielding RA. Muscle fiber size and function in elderly humans: a longitudinal study. J Appl Physiol 2008;105:637-642. (PMC2519941)

• Fleischman A, Johnsen S, Systrom DM, Hrovat M, Farrar C, Frontera WR, Fitch K, Thomas BJ, Torriani M, Côté HCF, Grinspoon SK. Effects of a nucleoside reverse transcriptase inhibitor, stavudine, on glucose disposal and mitochondrial function in muscle of healthy adults. Am J Physiol Endocrinol Metab 2007; 292:E1666-E1673. PMCID: PMC3206591

• Ochala J, Dorer D, Frontera WR, Krivickas LS. Single skeletal muscle fiber behavior after a quick stretch in young and older men: a possible explanation of the relative preservation of eccentric force in old age. Pflügers Archiv Europ J Physiol 2006; 452:464-470 (PMID:16622703).
• Frontera WR, Choi H, Krishnan G, Krivickas LS, Sabharwal S, Teng, YD. Single muscle fiber size and contractility after spinal cord injury in rats. Muscle Nerve 2006; 34:101-104 (PMID:16518854).

• Dolan SE, Frontera WR, Librizzi J, Ljunquist K, Juan S, Dorman R, Cole M, Kanter JR, Grinspoon S. The Effects of a Supervised Home-Based Aerobic and Progressive Resistance Training Regimen in Women infected with human immunodeficiency virus: A Randomized Trial. Arch Int Med 2006; 166:1225-1231 (PMID: 16772251).

• Teng, YD, Choi H, Huang W, Onario RC, Frontera WR, Snyder EY, Sabharwal S. Therapeutic effects of clenbuterol in a murine model of amyotrophic lateral sclerosis. Neuroscience Letters 2006; 397:155-158 (PMID:16388902).

• Choi H, Liao WL, Newton KM, Onario RC, King AM, Desilets FC, Woodard EJ, Eichler ME, Frontera WR, Sabharwal S, Teng YD. Respiratory abnormalities resulting from mid-cervical spinal cord injury and their reversal by serotonin 1A agonists in conscious rats. J. Neurosci 2005; 25:4550-4559 (PMID:15872102).

• Cai D, Frantz JD, Tawa NE, Jr., Melendez PA, Oh B-C, Lidov HGW, Hasselgren PO, Frontera WR, Lee J, Glass DJ, Shoelson SE. IKKβ/NF-κB activation causes severe muscle wasting in mice. Cell 2004; 119:285-298 (PMID:15479644).

• Hughes VA, Roubenoff R, Wood M, Frontera WR, Evans WJ, Fiatarone Singh, MA. Anthropometric assessment of 10-y changes in body composition in the elderly. Am J Clin Nutr 2004; 80:475-482 (PMID:15277173).

• Frontera WR, Hughes VA, Krivickas L, Kim SK, Foldvari M, Roubenoff R. Strength training in older women: early and late changes in whole muscle and single cells. Muscle & Nerve. 2003; 27:601-608 (PMID:14571463).

• Hughes VA, Frontera WR, Wood M, Evans WJ, Dallal GE, Roubenoff R, Fiatarone M. Longitudinal muscle strength changes in older adults: influence of muscle mass, physical activity and health. J Gerontol (Biol Sci) 2001; 56A:B209-17 (PMID:11320101).

• Fairfield WP, Treat M, Rosenthal D, Frontera WR, Stanley T, Corcoran C, Costello M, Parlman K, Schoenfeld D, Klibanski A, Grinspoon S. Effects of testosterone and exercise on muscle leanness in eugonadal men with AIDS wasting. J Appl Physiol 2001; 90:2166-71.

• Krivickas L, Suh D, Wilkins J, Hughes VA, Roubenoff R, Frontera WR. Age and sex related differences in maximum shortening velocity of skeletal muscle fibers. Am J PhysMed Rehabil 2001; 80:447-55 (PMID:11399006).

• Frontera WR, Hughes VA, Fielding RA, Fiatarone MA, Evans WJ, Roubenoff R. Aging of skeletal muscle: a 12 yr longitudinal study. J Appl Physiol 2000; 88:1321-6 (PMID: 10749826).

• Frontera WR, Krivickas L, Suh D, Hughes VA, Goldstein R, Roubenoff R. Skeletal muscle fiber quality in older men and women. Am J Physiol 2000; 279:C611-8 (PMID:10942711).

• Larsson L, Li X, Frontera WR. Effects of ageing on shortening velocity and myosin isoform composition in single skeletal muscle cells from man. Am J Physiol (Cell Physiol) 1997;272:C638-49 (PMID:9124308).

• Larsson L, Li X, Berg HE, Frontera WR. Effects of removal of weight-bearing function on contractility and myosin isoform composition in single human skeletal muscle cells. Pflügers Arch. (Europ J Physiol) 1996; 432:320-8 (PMID:8662283).

• Frontera WR, Meredith CN, O’Reilly KP, Evans WJ. Strength training and determinants of VO2 in older men. J Appl Physiol 1990; 68:329-33 (PMID:2312474).

• Frontera WR, Meredith CN, O’Reilly KP, Knuttgen HG, Evans WJ. Strength conditioning in older men: skeletal muscle function and mass. J Appl Physiol 1988; 64:1038-44 (PMID:3366726).