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Danielson TL, Gould LA, DeFreitas JM, MacLennan RJ, Ekstrand C, Borowsky R, Farthing JP, Andrushko JW. Activity in the pontine reticular nuclei scales with handgrip force in humans. J Neurophysiol 2024; 131:807-814. [PMID: 38505916 DOI: 10.1152/jn.00407.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/21/2024] [Accepted: 03/14/2024] [Indexed: 03/21/2024] Open
Abstract
The neural pathways that contribute to force production in humans are currently poorly understood, as the relative roles of the corticospinal tract and brainstem pathways, such as the reticulospinal tract (RST), vary substantially across species. Using functional magnetic resonance imaging (fMRI), we aimed to measure activation in the pontine reticular nuclei (PRN) during different submaximal handgrip contractions to determine the potential role of the PRN in force modulation. Thirteen neurologically intact participants (age: 28 ± 6 yr) performed unilateral handgrip contractions at 25%, 50%, 75% of maximum voluntary contraction during brain scans. We quantified the magnitude of PRN activation from the contralateral and ipsilateral sides during each of the three contraction intensities. A repeated-measures ANOVA demonstrated a significant main effect of force (P = 0.012, [Formula: see text] = 0.307) for PRN activation, independent of side (i.e., activation increased with force for both contralateral and ipsilateral nuclei). Further analyses of these data involved calculating the linear slope between the magnitude of activation and handgrip force for each region of interest (ROI) at the individual-level. One-sample t tests on the slopes revealed significant group-level scaling for the PRN bilaterally, but only the ipsilateral PRN remained significant after correcting for multiple comparisons. We show evidence of task-dependent activation in the PRN that was positively related to handgrip force. These data build on a growing body of literature that highlights the RST as a functionally relevant motor pathway for force modulation in humans.NEW & NOTEWORTHY In this study, we used a task-based functional magnetic resonance imaging (fMRI) paradigm to show that activity in the pontine reticular nuclei scales linearly with increasing force during a handgrip task. These findings directly support recently proposed hypotheses that the reticulospinal tract may play an important role in modulating force production in humans.
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Affiliation(s)
- Tyler L Danielson
- Applied Neuromuscular Physiology Laboratory, College of Education and Human Sciences, Oklahoma State University, Stillwater, Oklahoma, United States
| | - Layla A Gould
- Division of Neurosurgery, Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jason M DeFreitas
- Department of Exercise Science, Falk College of Sport and Human Dynamics, Syracuse University, Syracuse, New York, United States
| | - Rob J MacLennan
- Department of Neurology, College of Medicine, University of Florida, Gainesville, Florida, United States
- Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, Florida, United States
| | - Chelsea Ekstrand
- Department of Neuroscience, Faculty of Arts and Science, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Ron Borowsky
- Department of Psychology and Health Studies, College of Arts and Science, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jonathan P Farthing
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Justin W Andrushko
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
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Andrushko JW, Carr JC, Farthing JP, Lepley LK, DeFreitas JM, Goodall S, Hendy AM, Howatson G, Grooms DR, Zult T, Hortobagyi T, Harput G, Papandreou M, Nosaka K, Carson RG, Manca A, Deriu F, Behm DG, Kidgell DJ, Clark NC, Boyd LA. Potential role of cross-education in early-stage rehabilitation after anterior cruciate ligament reconstruction. Br J Sports Med 2023; 57:1474-1475. [PMID: 37821207 DOI: 10.1136/bjsports-2023-107456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2023] [Indexed: 10/13/2023]
Affiliation(s)
- Justin W Andrushko
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Joshua C Carr
- Department of Kinesiology, Texas Christian University, Fort Worth, Texas, USA
- School of Medicine, Department of Medical Education, Texas Christian University, Fort Worth, Texas, USA
| | - Jonathan P Farthing
- College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Lindsey K Lepley
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, College of Education and Human Sciences, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Stuart Goodall
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Ashlee M Hendy
- School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
| | - Glyn Howatson
- Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Dustin R Grooms
- Division of Athletic Training, School of Rehabilitation and Communications Science, College of Health Sciences and Professionals, & Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, Ohio, USA
| | - Tjerk Zult
- Vision and Eye Research Institute, School of Medicine, Faculty of Health, Education, Medicine, and Social Care, Anglia Ruskin University, Cambridge, UK
| | - Tibor Hortobagyi
- Kinesiology, Hungarian University of Physical Education, Budapest, Hungary
- Institute of Sport Sciences and Physical Education, University of Pécs, Pécs, Hungary
| | - Gulcan Harput
- Faculty of Physical Therapy and Rehabilitation, Hacettepe University, Ankara, Turkey
| | - Maria Papandreou
- Physiotherapy, University of West Attica, Egaleo, Attica, Greece
| | - Kazunori Nosaka
- School of Medical and Health Science, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Richard G Carson
- Trinity College Institute of Neuroscience and School of Psychology, Trinity College Dublin, Dublin, Ireland
| | - Andrea Manca
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Franca Deriu
- Department of Biomedical Sciences, University of Sassari, Sassari, Italy
- Unit of Endocrinology, Nutritional and Metabolic Disorders, AOU Sassari, Sassari, Italy
| | - David George Behm
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | - Dawson J Kidgell
- Department of Physiotherapy, School of Primary and Allied Health Care, Faculty of Medicine, Nursing and Health Science, Monash University, Clayton, Victoria, Australia
| | - Nicholas C Clark
- School of Sport, Rehabilitation, and Exercise Sciences, University of Essex, Colchester, UK
| | - Lara A Boyd
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
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Pagan JI, Harmon KK, Girts RM, MacLennan RJ, Beausejour JP, Hernandez-Sarabia JA, Coker NA, Carr JC, Ye X, DeFreitas JM, Stock MS. Sex-Specific Reliability of Lower-Limb Corticospinal Excitability and Silent Periods. J Strength Cond Res 2023; 37:1882-1887. [PMID: 37267320 DOI: 10.1519/jsc.0000000000004525] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
ABSTRACT Pagan, JI, Harmon, KK, Girts, RM, MacLennan, RJ, Beausejour, JP, Hernandez-Sarabia, JA, Coker, NA, Carr, JC, Ye, X, DeFreitas, JM, and Stock, MS. Sex-specific reliability of lower-limb corticospinal excitability and silent periods. J Strength Cond Res 37(9): 1882-1887, 2023-Transcranial magnetic stimulation (TMS) is a research tool that has potential to provide new insights into strength training-induced adaptations. However, using TMS to study the lower limbs is challenging, and sex-specific reliability has yet to be reported. We examined the reliability of corticospinal excitability and silent periods for the rectus femoris, vastus lateralis, and biceps femoris in both sexes. Thirteen males and 14 females reported to the laboratory twice. During both trials, a double cone coil was used to deliver 20 pulses to the rectus femoris hotspot with a stimulator output of 130% of active motor threshold. Motor-evoked potential peak-to-peak amplitude, which reflects corticospinal excitability, and silent period duration were quantified. Our results offer 4 novel findings. First, corticospinal excitability and silent period demonstrated higher reliability for the females. Second, regardless of sex and muscle, the silent period was more reliable than corticospinal excitability. Third, reliability was highest for our target muscle (rectus femoris), with lower reliability for the vastus lateralis and biceps femoris, suggesting that these methods cannot be used to study coactivation. Fourth, active motor threshold showed less variability than corticospinal excitability and silent period but increased at trial 2 in females. Many of the intraclass correlation coefficients were excellent (≥0.90), although we attribute this finding to variability between subjects. Reliability of lower-limb TMS measures may be sex, muscle, and variable dependent. Our findings suggest that both males and females should be included in lower-limb TMS research, although combining data between sexes should be approached cautiously.
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Affiliation(s)
- Jason I Pagan
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, Florida
| | - Kylie K Harmon
- Department of Exercise Science, Syracuse University, Syracuse, New York
| | - Ryan M Girts
- Department of Natural and Health Sciences, Pfeiffer University, Misenheimer, North Carolina
| | - Rob J MacLennan
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Jonathan P Beausejour
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, Florida
| | - Jesus A Hernandez-Sarabia
- Posture and Gait Neuromechanics Laboratory, California State University, Bakersfield, Bakersfield, California
| | - Nicholas A Coker
- Department of Exercise Science and Athletic Training, Springfield College, Springfield, Massachusetts
| | - Joshua C Carr
- Department of Kinesiology, Texas Christian University, Fort Worth, Texas
- Department of Medical Education, Texas Christian University School of Medicine, Fort Worth, Texas; and
| | - Xin Ye
- Doctor of Physical Therapy Program, Department of Rehabilitation Sciences, University of Hartford, West Hartford, Connecticut
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Matt S Stock
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, Florida
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MacLennan RJ, Hernandez-Sarabia JA, Pagan JI, Girts RM, Harmon KK, Stute K, Coker NA, Carr JC, Ye X, Stock MS, DeFreitas JM. Sensitivity Of Fnirs Brain Imaging To Determine Hemispheric Laterality During Lower-body Motor Tasks. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000882148.77052.04] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Chavez L, Barrera-Curiel A, Shields J, Hernandez-Sarabia JA, Danielson T, MacLennan RJ, DeFreitas JM. Is There A Relationship Between Antagonist Coactivation And Reaction Time During Dual-tasks? Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000882156.47410.1b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mackey CS, Thiele RM, Sanders DJ, DeFreitas JM. Effects of a thorstensson fatiguing protocol on isometric and isokinetic performance. ISOKINET EXERC SCI 2022. [DOI: 10.3233/ies-220010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE: Having participants perform 50 maximal isokinetic contractions, as introduced by Thorstensson and Karlsson (1976), is to this day one of the most commonly used fatigue protocols. Purpose: To determine to what extent a Thorstensson fatiguing protocol affects isokinetic and isometric performance characteristics. METHODS: Twenty-five college-aged men performed an isokinetic fatigue protocol consisting of 50 maximal elbow flexions at a moderate speed (180∘⋅s-1). Pre- and post-tests were used to calculate fatigue indices (FI%) for the following variables: isometric and isokinetic peak torque (PT), isometric rate of torque development (RTD), and maximum acceleration (ACCmax). RESULTS: Each of the four dependent variables significantly decreased with fatigue (each demonstrated p< 0.001), but not of the same magnitude. Isometric PT FI (-18.7%) was significantly less than isokinetic PT FI (-45.1%, p⩽ 0.001) and ACCmax FI (-26.3%) was significantly less than isometric RTD FI (-54.9%, p⩽ 0.001). There was a significant positive relationship between isometric and isokinetic PT FI% (r= 0.60, p< 0.002) as well as between isometric PT FI% and RTD FI% (r= 0.40, p< 0.046). There was no significant relationship observed between RTD FI% and ACCmax FI% nor between isokinetic PT FI% and ACCmax FI%. CONCLUSIONS: This investigation observed different patterns of response in maximal strength between isometric and isokinetic assessments following a isokinetic fatigue protocol. Additionally, the ability to rapidly generate strength and velocity had significantly different responses to fatigue between isometric and dynamic assessments. Due to these different responses, we recommend that assessments of fatigue at least include the same testing modality as the modality of the fatigue protocol.
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Affiliation(s)
- Cameron S. Mackey
- Human Performance Laboratory, Loyola University Chicago, Chicago, IL, USA
| | - Ryan M. Thiele
- Applied Physiology and Sports Medicine Laboratory, Kansas State University, Manhattan, KS, USA
| | - David J. Sanders
- Human Performance Laboratory, Loyola University Chicago, Chicago, IL, USA
| | - Jason M. DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
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Magrini MA, Colquhoun RJ, Ferrell MC, Fleming SR, Mota JA, Siedlik JA, Poidomani NM, Jenkins NDM, DeFreitas JM. The Influence of Motor Unit Number and Muscle Activation on Early Phase Rate of Torque Development in Younger and Older Men. J Mot Behav 2021; 54:422-428. [PMID: 34763617 DOI: 10.1080/00222895.2021.2001412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
This study examined the influence of muscle activation and motor unit number estimation (MUNE) on early phase voluntary rate of torque development (RTD) in younger (YM) and older (OM) men. Thirty-two YM (n = 17; Age = 22 yrs) and OM (n = 15; Age = 74 yrs) volunteered to participate in this study. Early phase RTD (first 50 ms of a rapid isometric contraction; RTD50) and normalized surface electromyography (first 50 ms of muscle excitation; nEMG50) were recorded from the right quadricep muscle group. MUNE was examined from the right vastus lateralis. Multiple linear regression analyses revealed that nEMG50 had a significant effect on RTD50 independent of age group (p ≤ 0.001). nEMG50 had a significant effect on RTD50 in the OM group (p = 0.037). MUNE had no effect on RTD50 independent of age. Older adults may depend more on muscle activation at contraction onset of early phase RTD compared to younger adults.
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Affiliation(s)
| | | | - Matt C Ferrell
- Oklahoma State University Center for Health Sciences, Tulsa, OK, USA
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Carr JC, Bemben MG, Stock MS, DeFreitas JM. Ipsilateral and contralateral responses following unimanual fatigue with and without illusionary mirror visual feedback. J Neurophysiol 2021; 125:2084-2093. [PMID: 33909484 DOI: 10.1152/jn.00077.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Illusionary mirror visual feedback alters interhemispheric communication and influences cross-limb interactions. Combining forceful unimanual contractions with the mirror illusion is a convenient way to provoke robust alterations within ipsilateral motor networks. It is unknown, however, if the mirror illusion affects cross-limb fatigability. We examine this concept by comparing the ipsilateral and contralateral handgrip force and electromyographic (EMG) responses following unimanual fatigue with and without illusionary mirror visual feedback. Participants underwent three experimental sessions (mirror, no-mirror, and control), performing a unimanual fatigue protocol with and without illusionary mirror visual feedback. Maximal handgrip force and EMG activity were measured before and after each session for both hands during maximal unimanual and bimanual contractions. The associated EMG activity from the inactive forearm during unimanual contraction was also examined. The novel findings demonstrate greater relative fatigability during bimanual versus unimanual contraction following unimanual fatigue (-31.8% vs. -23.4%, P < 0.01) and the mirror illusion attenuates this difference (-30.3% vs. -26.3%, P = 0.169). The results show no evidence for a cross-over effect of fatigue with (+0.62%, -2.72%) or without (+0.26%, -2.49%) the mirror illusion during unimanual or bimanual contraction. The mirror illusion resulted in significantly lower levels of associated EMG activity in the contralateral forearm. There were no sex differences for any of the measures of fatigability. These results demonstrate that the mirror illusion influences contraction-dependent fatigue during maximal handgrip contractions. Alterations in facilitatory and inhibitory transcallosal drive likely explain these findings.NEW & NOTEWORTHY Illusionary mirror visual feedback is a promising clinical tool for motor rehabilitation, yet many features of its influence on motor output are unknown. We show that maximal bimanual force output is compromised to a greater extent than unimanual force output following unimanual fatigue, yet illusionary mirror visual feedback attenuates this difference. The mirror illusion also reduces the unintended EMG activity of the inactive, contralateral forearm during unimanual contraction.
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Affiliation(s)
- Joshua C Carr
- Department of Kinesiology, Texas Christian University, Fort Worth, Texas.,Department of Medical Education, TCU and UNTHSC School of Medicine, Fort Worth, Texas
| | - Michael G Bemben
- Department of Health and Exercise Science, University of Oklahoma, Norman, Oklahoma
| | - Matt S Stock
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, Florida.,Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, Florida
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
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Mackey CS, Johnson Q, Dawes JJ, DeFreitas JM. Physical Performance Among Air Force ROTC Cadets Following Non-Mandatory Training. Aerosp Med Hum Perform 2020; 91:818-823. [PMID: 33187569 DOI: 10.3357/amhp.5622.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION: Due to the standard collegiate academic calendar (two semesters), U.S. Air Force Reserve Officers Training Corps (ROTC) cadets have an approximate 3-mo break over the summer in which physical training (PT) is neither regulated nor required. The purpose of this investigation was to determine if significant changes in cadet physical fitness assessment (PFA) scores occur after a 3-mo summer break when training is not mandatory.METHODS: Male (N 28) and female (N 10) cadets performed the PFA in April and August. Cadets were split into two groups depending on if they participated in field training over the summer [FT; N 12 (men 6, women 6)] or did not [NFT; N 26 (men 22, women 4)] to determine if engaging in field training had any effect on performance.RESULTS: Cadets performed significantly better on run time (7%), pushups (7.6%), sit-ups (5.8%), and overall composite score (3.6%) before summer break compared to after. Significant time group interactions were observed for abdominal circumference and run time. Abdominal circumference paired samples t-tests indicated that while the FT group did not differ between the spring and fall time points, the NFT did. There was a main effect for time in which cadets had a significantly larger abdominal circumference in the spring compared to the fall semester.CONCLUSION: Nonmandatory physical training over summer break may significantly decrease a cadets performance on the PFA. Additionally, it appears that even the inclusion of field training for some cadets was not enough to prevent the detraining that took place over summer break.Mackey CS, Johnson Q, Dawes JJ, DeFreitas JM. Physical performance among Air Force ROTC cadets following non-mandatory training. Aerosp Med Hum Perform. 2020; 91(10):818823.
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10
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Hernandez-Sarabia JA, Luera MJ, Barrera-Curiel A, Estrada CA, DeFreitas JM. Does strict validation criteria for individual motor units alter population-based regression models of the motor unit pool? Exp Brain Res 2020; 238:2475-2485. [PMID: 32844233 DOI: 10.1007/s00221-020-05906-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 08/14/2020] [Indexed: 01/03/2023]
Abstract
The purpose of this study was to determine if the implementation of a strict validation procedure, designed to limit the inclusion of inaccuracies from the decomposition of surface electromyographic (sEMG) signals, affects population-based motor unit (MU) analyses. Four sEMG signals were obtained from the vastus lateralis of 59 participants during isometric contractions at different relative intensities [30%, 70%, and 100% of maximal voluntary contraction (MVC)], and its individual motor unit potential trains (MUPTs) were extracted. The MUPTs were then excluded (ISIval) based on the coefficient of variation and histogram of the interspike intervals (ISI), the absence of additional clusters that reveals missed or additional firings, and more. MU population-based regression models (i.e., modeling the entire motor unit pool) were performed between motor unit potential size (MUPSIZE), mean firing rate (MFR), and recruitment threshold (RT%) separately for DSDCOnly (includes all MUPTs without the additional validation performed) and ISIval data at each contraction intensity. The only significant difference in regression coefficients between DSDCOnly and ISIval was for the intercepts of the MUPSIZE/MFR at 100% MVC. The validation had no other significant effect on any of the other regression coefficients for each of the contraction intensities. Our findings suggest that even though the decomposition of surface signals leads to some inaccuracies, these errors have limited effects on the regression models used to estimate the behavior of the whole pool. Therefore, we propose that motor unit population-based regression models may be robust enough to overcome decomposition-induced errors at the individual MU level.
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Affiliation(s)
| | - Micheal J Luera
- School of Kinesiology, Tarleton State University, Stephenville, TX, USA
| | - Alejandra Barrera-Curiel
- Posture and Gait Neuromechanics Laboratory, California State University Bakersfield, Bakersfield, CA, USA
| | - Carlos A Estrada
- School of Education and Human Performance, Aurora University, Aurora, IL, USA
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA.
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Luera MJ, Hernandez-Sarabia JA, Estrada CA, DeFreitas JM. ARE MOTOR UNIT FIRING PROPERTIES CONTROLLED WITHIN DISTINCT REGIONS OF A MUSCLE. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685776.52579.c2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Magrini M, Colquhoun RJ, Fleming S, Ferrell MC, Jenkins ND, DeFreitas JM. Physiological Determinants Of The Rate Of Torque Development In Older Men: A Pilot Study. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685784.82356.a9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Barrera - Curiel A, Colquhoun RJ, Hernandez - Sarabia JA, DeFreitas JM. Quantifying The Relationship Between Contraction Efficiency And Muscle Size Across The Adult Lifespan. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000679216.93061.ff] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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MacLennan RJ, Swafford AP, Kwon DP, DeFreitas JM, Stock MS. Do Decreases In Voluntary Activation Account For Fatigability Differently In Males And Females? Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685684.83393.3c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Shields JE, Hernandez-Sarabia JA, Barrera-Curiel A, Luera MJ, DeFreitas JM. Does Muscle Glycogen Content Account For The Contralateral Force Deficit During Unilateral Fatigue? Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000684448.56242.e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hernandez-Sarabia JA, Barrera-Curiel A, Luera MJ, DeFreitas JM. Does Ipsilateral Motor Cortex Activity During Unilateral Fatigue Explain The Deficits In The Non-fatigued Limb? Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685804.75654.58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Estrada CA, Moghaddam M, Luera MJ, Muddle TW, Mackey CS, Diehl CL, DeFreitas JM, Jacobson BH. Neuromodulation Does Not Enhance Neural Adaptations To Strength Training In Previously Trained Individuals. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000675884.75952.be] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mackey CS, DeFreitas JM. A longitudinal analysis of the U.S. Air Force reserve officers' training corps physical fitness assessment. Mil Med Res 2019; 6:30. [PMID: 31543076 PMCID: PMC6755694 DOI: 10.1186/s40779-019-0219-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 09/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The U.S. Air Force physical fitness assessment (PFA) is used to determine the overall fitness of their personnel. It is currently unknown to what extent the PFA scores of Reserve Officers' Training Corps (ROTC) cadets are affected by mandatory physical training. The purpose of this investigation was to longitudinally examine the PFAs of ROTC cadets over a four-year period, evaluate the results across class ranks, and evaluate the sensitivity of the classification of the tests. METHODS Air Force ROTC cadets performed the PFAs (abdominal circumference, 1-min pushups, 1-min sit-ups, and a 1.5-mile run) in both the spring (n = 26) and fall (n = 22) semesters. PFAs were compiled over a four-year period (Spring 2014 - Fall 2017) and were performed in accordance with Air Force Instruction 36-2905. A one-way repeated measures ANOVA was performed separately for the fall and spring groups for each dependent variable across the 4 years. Additionally, a one-way between groups ANOVA was performed for each dependent variable during the time point (fall 2015; N = 46) with the most recorded cadets for each class rank. RESULTS Longitudinal assessments revealed a main effect of time (P = 0.010) on abdominal circumference; cadets had a smaller abdominal circumference in their freshman year than in their senior year. A main effect of time (P = 0.006) was also observed on sit-up quantity; cadets performed more sit-ups in their junior year than in their freshman year. Examining between class ranks during the same year (between-subjects ANOVA) revealed a main effect of class rank on sit-up quantity (P = 0.003); the freshmen completed fewer repetitions than the sophomores (P = 0.018) and the juniors did (P = 0.001). CONCLUSION The results indicated that only the sit-up component showed differences between class ranks. These findings suggest that the Air Force PFA may not be sensitive enough to detect changes in physical fitness or distinguish between class ranks regarding physical performance, even after years of training. This limitation may be in part due to the limited duration of training incorporated by the ROTC program (2 h per week), which provided a maintenance effect rather than improvement in physical performance. We recommend that more attention be directed to the efficacy of physical training, the sensitivity of measures included in the PFA, or both.
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Affiliation(s)
- Cameron S Mackey
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, 192 CRC, Stillwater, OK, 74078, USA
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, 192 CRC, Stillwater, OK, 74078, USA.
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Johnson QR, Mackey CS, Muddle TD, Smith DB, DeFreitas JM. Body Composition Comparison of Upper- and Underclass Reserve Officers' Training Corps Cadets. Aerosp Med Hum Perform 2019; 90:813-818. [PMID: 31426898 DOI: 10.3357/amhp.5355.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION: Body composition (BC) measurements are used to determine qualification for enlistment and to ensure active members are meeting standards. Although there is extensive research on BC in active-duty military, very few have examined ROTC cadets. The purpose of this study was to identify and quantify differences in BC between freshman/sophomore [underclass (UND)] and junior/senior [upperclass (UPP)] ROTC cadets by using bioelectrical impedance spectroscopy (BIS).METHODS: UND (N = 21) and UPP (N = 15) Air Force ROTC cadets volunteered for this study. BIS was used to measure fat mass percentage (FM%), fat free mass percentage (FFM%), total body water percentage (TBW%), extracellular fluid percentage (ECF%), and intracellular fluid percentage (ICF%). Separate one-way ANOVAs were run between UND and UPP for all dependent variables with a Bonferroni correction factor. Additionally, a Pearson correlation between abdominal circumference (AC) and FM% was conducted.RESULTS: No significant differences were observed between the UND and UPP groups' BMI. However, significant differences were observed for ECF%, ICF%, TBW%, FFM%, and FM% in which the UPP had a higher TBW%, ICF%, FFM%, and a lower ECF% and FM% compared to the UND.CONCLUSIONS: This study observed significant differences in BC across class ranks in ROTC cadets. Findings from this study suggest that due to an increased exposure to ROTC training, UPP cadets have a more ideal body composition (FFM% and FM%) when compared to UND cadets.Johnson QR, Mackey CS, Muddle TD, Smith DB, DeFreitas JM. Body composition comparison of upper- and underclass Reserve Officers Training Corps cadets. Aerosp Med Hum Perform. 2019; 90(9):813-818.
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Barrera-Curiel A, Colquhoun RJ, Hernandez-Sarabia JA, DeFreitas JM. The effects of vibration-induced altered stretch reflex sensitivity on maximal motor unit firing properties. J Neurophysiol 2019; 121:2215-2221. [DOI: 10.1152/jn.00326.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is well known that muscle spindles have a monosynaptic, excitatory connection with α-motoneurons. However, the influence of muscle spindles on human motor unit behavior during maximal efforts remains untested. It has also been shown that muscle spindle function, as assessed by peripheral reflexes, can be systematically manipulated with muscle vibration. Therefore, the purpose of this study was to analyze the effects of brief and prolonged vibration on maximal motor unit firing properties. A crossover design was used, in which each of the 24 participants performed one to three maximal knee extensions under three separate conditions: 1) control, 2) brief vibration that was applied during the contraction, and 3) after prolonged vibration that was applied for ~20 min before the contraction. Multichannel EMG was recorded from the vastus lateralis during each contraction and was decomposed into its constituent motor unit action potential trains. Surprisingly, an approximate 9% reduction in maximal voluntary strength was observed not only after prolonged vibration but also during brief vibration. In addition, both vibration conditions had a large, significant effect on firing rates (a decrease in the rates) and a small to moderate, nonsignificant effect on recruitment thresholds (a small increase in the thresholds). Therefore, vibration had a detrimental influence on both maximal voluntary strength and motor unit firing properties, which we propose is due to altered function of the stretch reflex pathway. NEW & NOTEWORTHY We used vibration to alter muscle spindle function and examined the vibration’s influence on maximal motor unit properties. We discovered that vibration had a detrimental influence on motor unit behavior and motor output by decreasing motor unit firing rates, increasing recruitment thresholds, which led to decreased maximal strength. We believe that understanding the role of muscle spindles during maximal contractions provides a deeper insight into motor control and sensorimotor integration.
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Affiliation(s)
| | - Ryan J. Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | | | - Jason M. DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
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Hernandez-Sarabia JA, Barrera-Curiel A, Colquhoun RJ, DeFreitas JM. Does Strict Validation Criteria for Individual Motor Units Alter Extrapolation Analyses of the Motor Unit Pool? Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561534.61729.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Estrada CA, Muddle TW, Mackey CS, Moghaddam M, DeFreitas JM, Jacobson BH. Acute Effects of Transcranial Direct Current Stimulation on Knee Extensor Torque-Producing Capabilities. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561539.99846.a4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Curiel AB, Colquhoun RJ, Hernandez-Sarabia JA, DeFreitas JM. Effects of Brief and Prolonged Vibration on Longitudinally Tracked Motor Units. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561540.99846.9f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mackey CS, Hernandez-Sarabia JA, Luera MJ, Barrera-Curiel A, DeFreitas JM. Comparison of Agonist and Antagonist Muscle Fatigue on Coactivation and Force Production. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561467.13475.c6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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DeFreitas JM. In regards to motor unit decomposition, are we caring about the right information? J Electromyogr Kinesiol 2019; 47:121-122. [PMID: 31078381 DOI: 10.1016/j.jelekin.2019.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 05/01/2019] [Indexed: 10/26/2022] Open
Affiliation(s)
- Jason M DeFreitas
- Applied Neuromuscular Physiology Lab, Oklahoma State University, Stillwater, OK 74078, USA.
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Carr JC, Ye X, Stock MS, Bemben MG, DeFreitas JM. The time course of cross-education during short-term isometric strength training. Eur J Appl Physiol 2019; 119:1395-1407. [PMID: 30949806 DOI: 10.1007/s00421-019-04130-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 03/26/2019] [Indexed: 10/27/2022]
Abstract
PURPOSE This study examined the time course of contralateral adaptations in maximal isometric strength (MVC), rate of force development (RFD), and rate of electromyographic (EMG) rise (RER) during 4 weeks of unilateral isometric strength training with the non-dominant elbow flexors. METHODS Twenty participants were allocated to strength training (n = 10, three female, two left hand dominant) or control (n = 10, three female, two left hand dominant) groups. Both groups completed testing at baseline and following each week of training to evaluate MVC strength, EMG amplitude, RFD and RER at early (RFD50, RER50) and late (RFD200, RER200) contraction phases for the dominant 'untrained' elbow flexors. The training group completed 11 unilateral isometric training sessions across 4 weeks. RESULTS The contralateral improvements for MVC strength (P < 0.01) and RFD200 (P = 0.017) were evidenced after 2 weeks, whereas RFD50 (P < 0.01) and RER50 (P = 0.02) showed significant improvements after 3 weeks. Each of the dependent variables was significantly (P < 0.05) greater than baseline values at the end of the training intervention for the trained arm. No changes in any of the variables were observed for the control group (P > 0.10). CONCLUSIONS Unilateral isometric strength training for 2-3 weeks can produce substantial increases in isometric muscle strength and RFD for both the trained and untrained arms. These data have implications for rehabilitative exercise design and prescription.
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Affiliation(s)
- Joshua C Carr
- Department of Health & Exercise Science, University of Oklahoma, 1401 Asp Ave, Room 104, Norman, OK, 73019, USA.
| | - Xin Ye
- Department of Health, Exercise Science, & Recreation Management, University of Mississippi, University, MS, USA
| | - Matt S Stock
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL, USA
| | - Michael G Bemben
- Department of Health & Exercise Science, University of Oklahoma, 1401 Asp Ave, Room 104, Norman, OK, 73019, USA
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
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Magrini MA, Colquhoun RJ, Barrera-Curiel A, Thiele RM, DeFreitas JM, Smith DB, Jenkins ND. Muscle size, strength, power, and echo intensity, but not specific tension, are affected by age in physically active adults. ISOKINET EXERC SCI 2018. [DOI: 10.3233/ies-172194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Mitchel A. Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
| | - Ryan J. Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
| | | | - Ryan M. Thiele
- Department of Food, Nutrition, Dietetics and Health, Kansas State University, Manhattan, KS, USA
| | - Jason M. DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
| | - Doug B. Smith
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
| | - Nathaniel D.M. Jenkins
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, USA
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Mackey CS, Thiele RM, Conchola EC, DeFreitas JM. Comparison of fatigue responses and rapid force characteristics between explosive- and traditional-resistance-trained males. Eur J Appl Physiol 2018; 118:1539-1546. [PMID: 29761311 DOI: 10.1007/s00421-018-3883-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/05/2018] [Indexed: 11/27/2022]
Abstract
PURPOSE To compare maximal and rapid force characteristics, as well as fatigability, between traditional (TRT) and explosive (ERT) resistance-trained men. METHODS Fourteen TRT (mean age = 25 years) and twelve ERT (mean age = 22 years) men performed rapid maximal contractions followed by an isokinetic fatigue protocol consisting of 50 maximal knee extension (KE) and flexions (KF) at a moderate speed (180° s-¹). Baseline measures included: isokinetic peak torque (PT), isometric rate of torque development (RTD0-50), peak acceleration (ACCmax), and peak velocity (Vmax). Changes in torque with fatigue were used to calculate a fatigue index (FI%). RESULTS The ERT group (M ± SD; 1199.05 ± 404.12) displayed a significantly higher isometric RTD0-50 (p = 0.049) during KE than the TRT group (931.73 ± 244.75). No other significant differences in the dependent variables (PT, FI%, ACCmax, Vmax; all p ≥ 0.05) were observed between groups (TRT vs. ERT) for either of the muscle groups (KE and KF). CONCLUSIONS The results of the present study indicated that only knee extension RTD was able to discriminate between the two groups. These findings suggest that rapid force production may be more sensitive at distinguishing training-specific muscular adaptations than peak acceleration or velocity.
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Affiliation(s)
- Cameron S Mackey
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Ryan M Thiele
- Applied Physiology and Sports Medicine Laboratory, Kansas State University, Manhattan, KS, 66506, USA
| | - Eric C Conchola
- Department of Wellness, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, OK, 74078, USA.
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Luera MJ, Estrada CA, Hernandez Sarabia JA, Troung J, Muddle TWD, DeFreitas JM. A Preliminary Comparison Of Muscle Pennation Angle Measures To Explain Variance In Maximal Force Production. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536913.61351.6e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ha PL, Hester GM, Colquhoun RJ, Magrini MA, Pope ZK, Barrera-Curiel A, Estrada CA, DeFreitas JM. Effects Of Resistance Training On Maximal Motor Unit Firing Rates In Young And Older Males. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536499.08903.69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Colquhoun RJ, Magrini MA, Haun CT, Muddle TW, Tomko PM, Luera MJ, Mackey CS, Vann CG, Martin JS, Young KC, DeFreitas JM, Roberts MD, Jenkins ND. Relationships between Motor Unit Behavior during Maximal Effort Contractions and Skeletal Muscle Phenotype. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000535746.29814.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Barrera-Curiel A, Magrini MA, Thiele RM, Hernandez-Sarabia JA, Colquhoun RJ, Tomko PM, Jenkins NDM, DeFreitas JM. Antagonist Coactivation During A Reactive Leg Drop In Young And Older Adults. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536922.37587.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mackey CS, Thiele RM, Conchola EC, DeFreitas JM. The Magnitude Of Hamstring Co-activation During A Knee Extension Is Dependent On Knee Flexor Strength. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536918.84221.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Thiele RM, DeFreitas JM. The Effects of Repeated Shortening or Lengthening Muscle Actions on Knee Extensor Position Sense. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536938.85114.9b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Olmos AA, Hester GM, Pope ZK, Magrini MA, Colquhoun RJ, Barrera-Curiel A, Estrada CA, DeFreitas JM. Ipsilateral and Contralateral Rapid Torque Adaptations To Unilateral Resistance Training In Young and Older Males. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536281.52104.5a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Magrini MA, Barrera-Curiel A, Thiele RM, Hernandez-Sarabia JA, Colquhoun RJ, Tomko PM, Jenkins ND, DeFreitas JM. Both Slower Sensory Response Time and Electromechanical Delay Explain Age-related Differences in the Reactive Leg Drop. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536969.04414.4d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hernandez Sarabia JA, Luera MJ, Estrada C, DeFreitas JM. Contribution Of Mono- And Bi-articular Muscle Sizes Of Single- And Multi-joint Maximal Strength. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000536914.61351.a0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Magrini MA, Thiele RM, Colquhoun RJ, Barrera-Curiel A, Blackstock TS, DeFreitas JM. The reactive leg drop: a simple and novel sensory-motor assessment to predict fall risk in older individuals. J Neurophysiol 2018; 119:1556-1561. [PMID: 29357449 DOI: 10.1152/jn.00713.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
There is need for a functional ability test that appropriately assesses the rapid integration of the sensory and motor systems required for older adults to recover from a slip. The purpose of this study was to assess the efficacy and reliability of a novel test, the reactive leg drop, for assessing sensory-motor function in older adults. Fourteen young (YW; mean age = 20 yr) and 11 older women (OW; mean age = 76 yr) participated in this study. For each drop, the leg was passively moved to full extension and then released. The subjects had to recognize their leg was free-falling and reactively kick up as quickly as possible during varying sensory conditions. To assess the leg drop's reliance on proprioception, other proprioceptive tests (e.g., patellar tendon reflexes and balance) were separately performed. Leg drops performed with the eyes closed ( P = 0.011) and with a blocked view of the leg ( P = 0.033) showed significant differences in drop angle between YW and OW. Significant relationships between leg drop conditions and balance were observed in OW that were not present within YW. When collapsed across groups, reflex latency was correlated with drop angle when the eyes were closed. The reactive leg drop was age sensitive, reliable, and likely reliant on proprioception, as shown by relationships to other sensory-motor assessments, such as balance and the patellar reflex. Although more research is needed, we propose that the reactive leg drop is an effective tool to assess sensory-motor integration in a manner that may mimic fall recovery. NEW & NOTEWORTHY The reactive leg drop was age sensitive and was significantly related to other sensory-motor assessments. The ability to accurately assess sensory-motor integration may aid clinicians, practitioners, and researchers in developing new interventions. The reactive leg drop presented in the current study is a potentially effective tool to assess sensory and motor integration in a manner that may mimic fall recovery.
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Affiliation(s)
- Mitchel A Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Ryan M Thiele
- Department of Food, Nutrition, Dietetics and Health, Kansas State University , Manhattan, Kansas
| | - Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | | | - Taryn S Blackstock
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
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Muddle TWD, Colquhoun RJ, Magrini MA, Luera MJ, DeFreitas JM, Jenkins NDM. Effects of fatiguing, submaximal high- versus low-torque isometric exercise on motor unit recruitment and firing behavior. Physiol Rep 2018; 6:e13675. [PMID: 29673119 PMCID: PMC5907942 DOI: 10.14814/phy2.13675] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 03/02/2018] [Indexed: 12/04/2022] Open
Abstract
The purpose of this investigation was to evaluate the effects of repeated, high- (HT: 70% MVIC) versus low-torque (LT: 30% MVIC) isometric exercise performed to failure on motor unit (MU) recruitment and firing behavior of the vastus lateralis. Eighteen resistance-trained males (23.1 ± 3.8 years) completed familiarization, followed by separate experimental sessions in which they completed either HT or LT exercise to failure in random order. LT exercise resulted in a greater time to task failure and a more dramatic decline in the muscle's force capacity, but the total work completed was similar for HT and LT exercise. An examination of the firing trains from 4670 MUs recorded during exercise revealed that firing rates generally increased during HT and LT exercise, but were higher during HT than LT exercise. Furthermore, recruitment thresholds (RT) did not significantly change during HT exercise, whereas the RT of the smallest MUs increased and the RT for the moderate to large MUs decreased during LT exercise. Both HT and LT exercise resulted in the recruitment of additional higher threshold MUs in order to maintain torque production. However, throughout exercise, HT required the recruitment of larger MUs than did LT exercise. In a few cases, however, MUs were recruited by individuals during LT exercise that were similar in size and original (pre) RT to those detected during HT exercise. Thus, the ability to achieve full MU recruitment during LT exercise may be dependent on the subject. Consequently, our data emphasize the task and subject dependency of muscle fatigue.
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Affiliation(s)
- Tyler W. D. Muddle
- Applied Neuromuscular Physiology LaboratoryOklahoma State UniversityStillwaterOklahoma
| | - Ryan J. Colquhoun
- Applied Neuromuscular Physiology LaboratoryOklahoma State UniversityStillwaterOklahoma
| | - Mitchel A. Magrini
- Applied Neuromuscular Physiology LaboratoryOklahoma State UniversityStillwaterOklahoma
| | - Micheal J. Luera
- Applied Neuromuscular Physiology LaboratoryOklahoma State UniversityStillwaterOklahoma
| | - Jason M. DeFreitas
- Applied Neuromuscular Physiology LaboratoryOklahoma State UniversityStillwaterOklahoma
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Colquhoun RJ, Magrini MA, Haun CT, Muddle TWD, Tomko PM, Luera MJ, Mackey CS, Vann CG, Martin JS, Young KC, DeFreitas JM, Roberts MD, Jenkins NDM. Muscle phenotype is related to motor unit behavior of the vastus lateralis during maximal isometric contractions. Physiol Rep 2018. [PMID: 29527830 PMCID: PMC5845862 DOI: 10.14814/phy2.13636] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Previous investigations have reported a relationship between skeletal muscle phenotype and motor unit (MU) firing parameters during submaximal contractions. The purpose of the current investigation, however, was to examine the relationships between motor unit firing behavior during a maximal voluntary contraction, Myosin Heavy Chain (MHC) isoform content, and various molecular neuromuscular targets of the vastus lateralis (VL) muscle in resistance-trained men. Ten resistance-trained males completed a trapezoidal ramp contraction up to 100% of their maximal voluntary isometric strength (MVIC). Surface electromyography was recorded from the VL using a multichannel electrode array and decomposed to examine the firing characteristics of individual MUs. A skeletal muscle biopsy of the VL was also collected from each subject. Regression analyses were performed to identify relationships between type II fiber area and the slopes and/or intercepts of the mean firing rate (FRMEAN ) versus recruitment threshold (RT), max firing rate (FRMAX ) versus RT, and RT versus MU action potential amplitude (MUAPPP ) relationships. There were significant inverse relationships between type II fiber area and the y-intercept of the FR versus RT relationship (P < 0.05). Additionally, strong relationships (r > 0.5) were found between type II fiber area and FRMEAN versus RT slope and RT versus MUAPPP slope and intercept. These data further support the hypothesis that skeletal muscle phenotype is related to MU behavior during isometric contraction. However, our data, in concert with previous investigations, may suggest that these relationships are influenced by the intensity of the contraction.
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Affiliation(s)
- Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Mitchel A Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Cody T Haun
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Tyler W D Muddle
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Patrick M Tomko
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Micheal J Luera
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Cameron S Mackey
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Christopher G Vann
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Jeffrey S Martin
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Kaelin C Young
- Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
| | - Michael D Roberts
- Molecular and Applied Sciences Laboratory, Auburn University, Auburn, Alabama
| | - Nathaniel D M Jenkins
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater, Oklahoma
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Haun CT, Mumford PW, Roberson PA, Romero MA, Mobley CB, Kephart WC, Anderson RG, Colquhoun RJ, Muddle TWD, Luera MJ, Mackey CS, Pascoe DD, Young KC, Martin JS, DeFreitas JM, Jenkins NDM, Roberts MD. Molecular, neuromuscular, and recovery responses to light versus heavy resistance exercise in young men. Physiol Rep 2017; 5:5/18/e13457. [PMID: 28963127 PMCID: PMC5617935 DOI: 10.14814/phy2.13457] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 08/30/2017] [Accepted: 09/04/2017] [Indexed: 11/24/2022] Open
Abstract
Recent evidence suggests that resistance training with light or heavy loads to failure results in similar adaptations. Herein, we compared how both training modalities affect the molecular, neuromuscular, and recovery responses following exercise. Resistance‐trained males (mean ± SE: 22 ± 2 years, 84.8 ± 9.0 kg, 1.79 ± 0.06 m; n = 15) performed a crossover design of four sets of leg extensor exercise at 30% (light RE) or 80% (heavy RE) one repetition maximum (1RM) to repetition failure, and heavy RE or light RE 1 week later. Surface electromyography (EMG) was monitored during exercise, and vastus lateralis muscle biopsies were collected at baseline (PRE), 15 min (15mPOST), and 90 min following RE (90mPOST) for examination of molecular targets and fiber typing. Isokinetic dynamometry was also performed before (PRE), immediately after (POST), and 48 h after (48hPOST) exercise. Dependent variables were analyzed using repeated measures ANOVAs and significance was set at P ≤ 0.05. Repetitions completed were greater during light RE (P < 0.01), while EMG amplitude was greater during heavy RE (P ≤ 0.01). POST isokinetic torque was reduced following light versus heavy RE (P < 0.05). Postexercise expression of mRNAs and phosphoproteins associated with muscle hypertrophy were similar between load conditions. Additionally, p70s6k (Thr389) phosphorylation and fast‐twitch fiber proportion exhibited a strong relationship after both light and heavy RE (r > 0.5). While similar mRNA and phosphoprotein responses to both modalities occurred, we posit that heavy RE is a more time‐efficient training method given the differences in total repetitions completed, lower EMG amplitude during light RE, and impaired recovery response after light RE.
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Affiliation(s)
- Cody T Haun
- School of Kinesiology, Auburn University, Auburn, Alabama
| | | | | | | | | | | | | | - Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater
| | - Tyler W D Muddle
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater
| | - Michael J Luera
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater
| | - Cameron S Mackey
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater
| | - David D Pascoe
- School of Kinesiology, Auburn University, Auburn, Alabama
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Jeffrey S Martin
- School of Kinesiology, Auburn University, Auburn, Alabama.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
| | - Jason M DeFreitas
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University, Stillwater
| | | | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama .,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine - Auburn Campus, Auburn, Alabama
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Martin JS, Mumford PW, Haun CT, Luera MJ, Muddle TWD, Colquhoun RJ, Feeney MP, Mackey CS, Roberson PA, Young KC, Pascoe DD, DeFreitas JM, Jenkins NDM, Roberts MD. Effects of a pre-workout supplement on hyperemia following leg extension resistance exercise to failure with different resistance loads. J Int Soc Sports Nutr 2017; 14:38. [PMID: 28959158 PMCID: PMC5615454 DOI: 10.1186/s12970-017-0195-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/20/2017] [Indexed: 01/24/2023] Open
Abstract
Background We sought to determine if a pre-workout supplement (PWS), containing multiple ingredients thought to enhance blood flow, increases hyperemia associated with resistance training compared to placebo (PBO). Given the potential interaction with training loads/time-under-tension, we evaluated the hyperemic response at two different loads to failure. Methods Thirty males participated in this double-blinded study. At visit 1, participants were randomly assigned to consume PWS (Reckless™) or PBO (maltodextrin and glycine) and performed four sets of leg extensions to failure at 30% or 80% of their 1-RM 45-min thereafter. 1-wk. later (visit 2), participants consumed the same supplement as before, but exercised at the alternate load. Heart rate (HR), blood pressure (BP), femoral artery blood flow, and plasma nitrate/nitrite (NOx) were assessed at baseline (BL), 45-min post-PWS/PBO consumption (PRE), and 5-min following the last set of leg extensions (POST). Vastus lateralis near infrared spectroscopy (NIRS) was employed during leg extension exercise. Repeated measures ANOVAs were performed with time, supplement, and load as independent variables and Bonferroni correction applied for multiple post-hoc comparisons. Data are reported as mean ± SD. Results With the 30% training load compared to 80%, significantly more repetitions were performed (p < 0.05), but there was no difference in total volume load (p > 0.05). NIRS derived minimum oxygenated hemoglobin (O2Hb) was lower in the 80% load condition compared to 30% for all rest intervals between sets of exercise (p < 0.0167). HR and BP did not vary as a function of supplement or load. Femoral artery blood flow at POST was higher independent of exercise load and treatment. However, a time*supplement*load interaction was observed revealing greater femoral artery blood flow with PWS compared to PBO at POST in the 80% (+56.8%; p = 0.006) but not 30% load condition (+12.7%; p = 0.476). Plasma NOx was ~3-fold higher with PWS compared to PBO at PRE and POST (p < 0.001). Conclusions Compared to PBO, the PWS consumed herein augmented hyperemia following multiple sets to failure at 80% of 1-RM, but not 30%. This specificity may be a product of interaction with local perturbations (e.g., reduced tissue oxygenation levels [minimum O2Hb] in the 80% load condition) and/or muscle fiber recruitment.
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Affiliation(s)
- Jeffrey S Martin
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, 910 S. Donahue Drive, Auburn, AL 36832 USA
| | - Petey W Mumford
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA
| | - Cody T Haun
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA
| | - Micheal J Luera
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, OK 74078 USA
| | - Tyler W D Muddle
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, OK 74078 USA
| | - Ryan J Colquhoun
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, OK 74078 USA
| | - Mary P Feeney
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA
| | - Cameron S Mackey
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, OK 74078 USA
| | - Paul A Roberson
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA
| | - Kaelin C Young
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, 910 S. Donahue Drive, Auburn, AL 36832 USA
| | - David D Pascoe
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA
| | - Jason M DeFreitas
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, OK 74078 USA
| | - Nathaniel D M Jenkins
- School of Kinesiology, Applied Health and Recreation, Oklahoma State University, Stillwater, OK 74078 USA
| | - Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849 USA.,Department of Cell Biology and Physiology, Edward Via College of Osteopathic Medicine-Auburn Campus, 910 S. Donahue Drive, Auburn, AL 36832 USA
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Barrera-Curiel A, Colquhoun RJ, Pope ZK, DeFreitas JM. An Examination of Patellar Tendon Reflex Pre-Motor Conduction Velocity across the Adult Lifespan. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519836.70695.73] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Olmos AA, Hester GG, Pope ZK, Colquhoun RJ, Magrini MA, Barrera-Curiel A, Estrada CA, DeFreitas JM. Maximal Velocity Adaptions During Unilateral Resistance Training In Older Adults. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000516959.37989.0d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Thiele RM, Warren AJ, DeFreitas JM. The Effects of Muscle Damage on Muscle Spindle Function. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000518171.91874.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Colquhoun RJ, Haun CT, Mumford PW, Roberson PA, Pascoe DD, Feeney MP, Young KC, Martin JS, Roberts MD, Muddle TW, Riffe JJ, Luera MJ, Magrini MA, Mackey CS, Stock MS, Jenkins ND, DeFreitas JM. The Effects Of A Muscle Biopsy On Motor Unit Firing Properties. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000518606.24233.6b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Luera MJ, Magrini MA, Muddle TW, Colquhoun RJ, DeFreitas JM, Dowling B, Jenkins ND. Differences Among Kinetics, Kinematics, Performance, and Elbow Varus Torque in Professional Versus High School Pitchers. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000518959.90165.ec] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Magrini MA, Colquhoun RJ, Barrera-Curiel A, Thiele RM, Muddle TW, DeFreitas JM, Smith DB, Jenkins ND. Relationships Among and Differences between Muscle Quality and Functional Performance in Younger and Older Women. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000516965.76107.41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mackey CS, Thiele RM, Magrini MA, DeFreitas JM. Relationship Between Estimated Muscle Fiber-type And Peak Velocity For The Upper And Lower Extremity. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519144.83924.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Estrada CA, Colquhoun RJ, Magrini MA, Speer AG, Jacobson BH, DeFreitas JM. Intra- And Inter-set Velocity Characteristics During High- And Low-load Resistance Training To Failure. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000517183.45883.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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