51
|
Krajewski KT, Bansbach HM, McLean L, McKenzie C, Rawcliffe A, Graham SM, Flanagan SD, Pourmoghaddam A, Dettmer M, Connaboy C. Effects of Short-Term Unilateral Strength Training on Measures of Postural Control When Wearing "Operationally Relevant" Backpack Loads. J Strength Cond Res 2020; 34:2743-2750. [PMID: 32956262 DOI: 10.1519/jsc.0000000000003794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Krajewski, KT, Bansbach, HM, McLean, L, McKenzie, C, Rawcliffe, A, Graham, SM, Flanagan, SD, Pourmoghaddam, A, Dettmer, M, and Connaboy, C. Effects of short-term unilateral strength training on measures of postural control when wearing "operationally relevant" backpack loads. J Strength Cond Res 34(10): 2743-2750, 2020-To examine the effects of "operationally relevant" loads on postural stability and to determine the effects of unilateral and bilateral strength training programs on postural stability in healthy, recruit-aged men. Fifteen subjects were randomly assigned to either a unilateral (UL; n = 7) or bilateral (BL; n = 8) strength training group, which performed strength training 3 times a week for 4 weeks. Subjects completed the following pretest and post-test assessments: 1 repetition maximum in bilateral (1RM-BL) and unilateral (1RM-UL) stance positions and bilateral and unilateral balance tasks with eyes open and eyes closed. Balance tasks were performed over 3 loading conditions: body mass (BM), 50% BM, and 70% BM. Sample entropy (SE) and root mean square (RMS) were calculated from the center of pressures collected during each balance assessment. The UL strength training group showed significant improvement after training in both 1RM-UL (p < 0.01) and 1RM-BL (p < 0.01). The BL strength training group only showed significant improvement in 1RM-BL (p = 0.01). There was a significant main effect of load on RMS (p < 0.05) across all balance tasks with RMS increasing with increasing load. Sample entropy was found to decrease with increasing load in the unilateral eyes open and bilateral stance tasks. Significant increases in strength (∼10 to -29%) were observed; however, increased strength alone is not enough to mitigate the effects of load carriage on the postural control, even when training is performed in stance positions that are posturally challenging. Therefore, "operationally relevant" loads negatively impact postural stability in novice load carriers when assessing nonlinear measures.
Collapse
|
52
|
Krajewski KT, Dever DE, Johnson CC, Mi Q, Simpson RJ, Graham SM, Moir GL, Ahamed NU, Flanagan SD, Anderst WJ, Connaboy C. Load Magnitude and Locomotion Pattern Alter Locomotor System Function in Healthy Young Adult Women. Front Bioeng Biotechnol 2020; 8:582219. [PMID: 33042981 PMCID: PMC7525027 DOI: 10.3389/fbioe.2020.582219] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/19/2020] [Indexed: 11/24/2022] Open
Abstract
Introduction During cyclical steady state ambulation, such as walking, variability in stride intervals can indicate the state of the system. In order to define locomotor system function, observed variability in motor patterns, stride regulation and gait complexity must be assessed in the presence of a perturbation. Common perturbations, especially for military populations, are load carriage and an imposed locomotion pattern known as forced marching (FM). We examined the interactive effects of load magnitude and locomotion pattern on motor variability, stride regulation and gait complexity during bipedal ambulation in recruit-aged females. Methods Eleven healthy physically active females (18–30 years) completed 1-min trials of running and FM at three load conditions: no additional weight/bodyweight (BW), an additional 25% of BW (BW + 25%), and an additional 45% of BW (BW + 45%). A goal equivalent manifold (GEM) approach was used to assess motor variability yielding relative variability (RV; ratio of “good” to “bad” variability) and detrended fluctuation analysis (DFA) to determine gait complexity on stride length (SL) and stride time (ST) parameters. DFA was also used on GEM outcomes to calculate stride regulation. Results There was a main effect of load (p = 0.01) on RV; as load increased, RV decreased. There was a main effect of locomotion (p = 0.01), with FM exhibiting greater RV than running. Strides were regulated more tightly and corrected quicker at BW + 45% compared (p < 0.05) to BW. Stride regulation was greater for FM compared to running. There was a main effect of load for gait complexity (p = 0.002); as load increased gait complexity decreased, likewise FM had less (p = 0.02) gait complexity than running. Discussion This study is the first to employ a GEM approach and a complexity analysis to gait tasks under load carriage. Reduction in “good” variability as load increases potentially exposes anatomical structures to repetitive site-specific loading. Furthermore, load carriage magnitudes of BW + 45% potentially destabilize the system making individuals less adaptable to additional perturbations. This is further evidenced by the decrease in gait complexity, which all participants demonstrated values similarly observed in neurologically impaired populations during the BW + 45% load condition.
Collapse
|
53
|
Eagle SR, Collins MW, Connaboy C, Flanagan SD, Kontos AP. A-15 Network Analysis Of Sport-Related Concussion Research During The Past Decade (2010–2019). Arch Clin Neuropsychol 2020. [DOI: 10.1093/arclin/acaa036.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Objective
The purpose of this study was to apply network analyses to evaluate trends in the literature using a comprehensive search of original, peer-reviewed research articles involving human participants with sport-related concussion (SRC) published between January 1, 2010 and December 31, 2019.
Data Selection
Articles were identified in a comprehensive online search using key terms to encompass all forms of SRC or mTBI and entered into a clustering algorithm (vosViewer). Each cluster (e.g., journal, institution, author, keyword) is named for the hub, or most highly interconnected individual node.
Data Synthesis
The online search yielded 6,130 articles, 528 journals, 7,598 authors, 1,966 institutions, and 3,293 keywords. The analysis supported five thematic clusters of journals: 1. Biomechanics/Sports medicine (n = 15), 2. Pediatrics/Rehabilitation (n = 15), 3. Neurotrauma/Neurology/Neurosurgery (n = 11), 4. General Sports Medicine (n = 11), 5. Neuropsychology (n = 7). The analysis identified four institutional clusters: 1. University of North Carolina (n = 19), 2. University of Toronto (n = 19), 3. University of Michigan (n = 11), 4. University of Pittsburgh (n = 10). Five primary author clusters were identified: 1. A. Kontos (n = 32), 2. G. Iverson (n = 27), 3. M. McCrea (n = 27), 4. S. Broglio (n = 25), 5. Z. Kerr (n = 16). In regards to keywords, central topics included: 1. Epidemiology (n = 14), 2. Rehabilitation (n = 12), 3. Biomechanics (n = 11), 4. Imaging (n = 10), 5. Assessment (n = 9).
Conclusions
The findings suggest that during the past decade SRC research has: 1) been published primarily in sports medicine, pediatric, and neuro-focused journals, 2) involved a select group of researchers from several key institutions, and 3) focused on new topic areas including treatment/rehabilitation.
Collapse
|
54
|
Proessl F, Canino MC, Sterczala AJ, Sciavolino BM, Dunn-Lewis C, Conkright WR, Sinnott AM, Beckner ME, Eagle SR, Ferrarelli F, Germain A, Connaboy C, Nindl BC, Flanagan SD. Task-specificity Of Corticospinal Excitability: The Influence Of Contractile Properties. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000681080.47040.4b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
55
|
Canino MC, Proessl F, Sterczala AJ, Dunn-Lewis C, Conkright WC, Sinnott AM, LaGoy A, Beckner ME, Eagle SR, Ferrarelli F, Germain A, Connaboy C, Nindl BC, Flanagan SD. Impact Of Operational Stress On Motor Evoked Potentials In Military Personnel. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000681140.17473.39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
56
|
Conkright WR, Beckner ME, Martin BJ, Sinnott AM, LaGoy AD, Proessl F, Eagle SR, Flanagan SD, Connaboy C, Germain A, Nindl BC. Differential Responses Of Resting Vs. Post-exertion Hormone Concentrations During Simulated Military Operational Stress. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000687632.25953.69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
57
|
Ahamed NU, Krajewsk KT, Johnson CC, Sterczala AJ, Greeves JP, Greeves JP, Wardle SL, O'Leary TJ, Mi Q, Flanagan SD, Nindl BC, Connaboy C. Foot Acceleration Attenuation Reduces During Military Load Carriage. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000675484.17929.38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
58
|
Beckner ME, Martin BJ, Conkright WR, Eagle SR, Sinnott AM, LaGoy AD, Prossel F, Flanagan SD, Germain A, Roma PG, Dretsch MN, Connaboy C, Nindl BC. Simulated Military Operational Stress Negatively Impacts Psychomotor Vigilance And Neurocognitive Biomarkers In Men And Women. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000676928.67602.f7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
59
|
LaGoy AD, Eagle SR, Sinnott AM, Beckner ME, Conkright WR, Flanagan SD, Martin BJ, Nindl BC, Ferrarelli F, Germain A, Connaboy C. Compromised Perception-action Coupling Performance In Military Personnel May Be Related To Increased Deep Sleep. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000675476.37212.51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
60
|
Beckner ME, Pihoker AA, Darnell ME, Beals K, Lovalekar M, Proessl F, Flanagan SD, Arciero PJ, Nindl BC, Martin BJ. Effects of Multi-ingredient Preworkout Supplements on Physical Performance, Cognitive Performance, Mood State, and Hormone Concentrations in Recreationally Active Men and Women. J Strength Cond Res 2020; 36:2493-2501. [PMID: 32569125 DOI: 10.1519/jsc.0000000000003660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Beckner, ME, Pihoker, AA, Darnell, ME, Beals, K, Lovalekar, M, Proessl, F, Flanagan, SD, Arciero, PJ, Nindl, BC, and Martin, BJ. Effects of multi-ingredient preworkout supplements on physical performance, cognitive performance, mood state, and hormone concentrations in recreationally active men and women. J Strength Cond Res XX(X): 000-000, 2020-Performance enhancement supplement research has primarily focused on the effectiveness of individual ingredients, rather than the combination. This study investigated the acute effects of 2 multi-ingredient preworkout supplements (MIPS), with beta-alanine and caffeine (BAC) and without (NBAC), compared with placebo (PLA) on anaerobic performance, endurance capacity, mood state, cognitive function, vascular function, and anabolic hormones. Thirty exercise-trained individuals (24.4 ± 4.9 years, 15 men and 15 women) completed a fatiguing exercise protocol on 3 separate occasions, 30 minutes after ingestion of BAC, NBAC, or PLA. Outcomes were analyzed using one-way or two-way repeated-measures analysis of variance, as appropriate (alpha = 0.05). Anaerobic power was greater when supplementing with NBAC (10.7 ± 1.2 W·kg) and BAC (10.8 ± 1.4 W·kg) compared with PLA (10.4 ± 1.2 W·kg) (p = 0.014 and p = 0.022, respectively). BAC improved V[Combining Dot Above]O2peak time to exhaustion (p = 0.006), accompanied by an increase in blood lactate accumulation (p < 0.001), compared with PLA. Both NBAC and BAC demonstrated improved brachial artery diameter after workout (p = 0.041 and p = 0.005, respectively), but PLA did not. L-arginine concentrations increased from baseline to postsupplement consumption of BAC (p = 0.017). Reaction time significantly decreased after exercise for all supplements. There was no effect of supplement on mood states. Exercise-trained individuals looking to achieve modest improvements in power and endurance may benefit from consuming MIPS before exercise.
Collapse
|
61
|
LaGoy AD, Eagle SR, Sinnott AM, Beckner ME, Conkright WR, Flanagan SD, Martin BJ, Nindl BC, Germain A, Ferrarelli F, Connaboy C. 0242 Efficient Perception-Action Coupling Relates to More Slow Wave Sleep in Military Personnel. Sleep 2020. [DOI: 10.1093/sleep/zsaa056.240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Introduction
The ability to adapt actions to perceptions of environmental constraints, perception-action coupling, may be compromised by military operational stress (caloric restriction, sleep disruption, physical exertion). Differences in sleep may influence susceptibility to these stressors. We investigated perception-action coupling during simulated military operational stress and the influence of sleep on perception-action coupling.
Methods
During a 5-day simulated military operational stress protocol, thirty-six (6 female) service members (25.8 ± 4.7 years) completed three trials of a perception-action coupling task (PACT) in the evening after a night of baseline sleep (BASE), two nights of sleep restriction (T1) and a night of recovery sleep (T2). Participants had 8-hr for baseline and recovery sleep (2300-0700) and 4-hr disturbed sleep on sleep restriction nights (0100-0300 and 0500-0700). Polysomnography was used to determine time spent in different sleep stages: stage 2 (N2), slow wave (SWS) and rapid-eye movement (REM). The tablet-based PACT requires participants make quick, accurate perceptual judgments and responses about the ability of virtual balls to fit through virtual apertures. Linear mixed models were used to assess interaction and main effects of study day and prior sleep on PACT response time (RT) and accuracy (ACC).
Results
No significant sleep x time interactions or significant main effect of time were found for RT or ACC. A significant main effect of SWS was found for RT (F1,88.307 = 4.331, p = .04). Higher SWS was related to lower (faster) RT. No significant main effects of other sleep stages were found.
Conclusion
Perception-action coupling was maintained during simulated military operational stress. Participants with more SWS across the study responded faster during the PACT but N2 and REM sleep did not relate to perception-action coupling performance, suggesting a specific effect of SWS on perception-action coupling abilities and behaviors.
Support
Department of Defense Award #W81XWH-17-2-0070 (PI: Nindl)
Collapse
|
62
|
Eagle SR, Kontos AP, Sinnott A, Beckner M, Nindl BC, Flanagan SD, Lovalekar M, Connaboy C. Utility of a novel perceptual-motor control test for identification of sport-related concussion beyond current clinical assessments. J Sports Sci 2020; 38:1799-1805. [PMID: 32412332 DOI: 10.1080/02640414.2020.1756675] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Clinically feasible metrics, that can inform the concussion recovery decision making process by evaluating a unique domain beyond current testing domains (e.g., balance, neurocognition, symptoms, vestibular/ocular function) are still in need. The purpose of this study was to compare perceptual-motor control in adolescent athletes ≤21 days of sport-related concussion and healthy controls and evaluate the association of perceptual-motor control to the outcomes of commonly-used sport-related concussion clinical assessments. Athletes (age: 12-18 years) with sport-related concussion (n = 48) and healthy controls (n = 24) completed the Perception-Action Coupling Task (PACT), whose outcomes are mean reaction, movement, initiation, response time, and accuracy. ImPACT outcomes are verbal/visual memory scores, motor processing speed, and reaction time. Vestibular-Ocular Motor Screen (VOMS) outcomes are symptoms from: smooth pursuit, horizontal/vertical saccades, near-point of convergence, horizontal/vestibular ocular-reflex, and visual motion sensitivity. CONCUSSED demonstrated ~5% deficit in overall perceptual-motor accuracy during PACT compared to CONTROLS (p = 0.03). PACT accuracy negatively correlated with smooth pursuits(r = -0.29), and horizontal (r = -0.35)/vertical (r = -0.30) saccades. The C5.0 decision tree determined PACT accuracy was the most relevant predictor of sport-related concussion when no visual motion sensitivity symptoms were reported and Visual Memory was >66. Perceptual-motor control tests may complement current sport-related concussion assessments when neurocognition and vestibular/ocular motor system are not grossly impaired.
Collapse
|
63
|
Flanagan SD, Proessl F, Dunn-Lewis C, Canino MC, Sterczala AJ, Connaboy C, DuPont WH, Caldwell LK, Kraemer WJ. Constitutive and Stress-Induced Psychomotor Cortical Responses to Compound K Supplementation. Front Neurosci 2020; 14:315. [PMID: 32322188 PMCID: PMC7158875 DOI: 10.3389/fnins.2020.00315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/17/2020] [Indexed: 12/14/2022] Open
Abstract
Isolated ginsenoside metabolites such as Compound K (CK) are of increasing interest to consumer and clinical populations as safe and non-pharmacological means to enhance psychomotor performance constitutively and in response to physical or cognitive stress. Nevertheless, the influence of CK on behavioral performance and EEG measures of cortical activity in humans is undetermined. In this double-blinded, placebo-controlled, counterbalanced within-group study, dose-dependent responses to CK (placebo, 160 and 960 mg) were assessed after 2 weeks of supplementation in nineteen healthy men and women (age: 39.9 ± 7.9 year, height 170.2 ± 8.6 cm, weight 79.7 ± 11.9 kg). Performance on upper- and lower-body choice reaction tests (CRTs) was tested before and after intense lower-body anaerobic exercise. Treatment- and stress-related changes in brain activity were measured with high-density EEG based on event-related potentials, oscillations, and source activity. Upper- (−12.3 ± 3.5 ms, p = 0.002) and lower-body (−12.3 ± 4.9 ms, p = 0.021) response times improved after exercise, with no difference between treatments (upper: p = 0.354; lower: p = 0.926). Analysis of cortical activity in sensor and source space revealed global increases in cortical arousal after exercise. CK increased activity in cortical regions responsible for sustained attention and mitigated exercise-induced increases in arousal. Responses to exercise varied depending on task, but CK appeared to reduce sensory interference from lower-body exercise during an upper-body CRT and improve the general maintenance of task-relevant sensory processes.
Collapse
|
64
|
Krajewski KT, Dever DE, Johnson CC, Rawcliffe AJ, Ahamed NU, Flanagan SD, Mi Q, Anderst WJ, Connaboy C. Load carriage magnitude and locomotion strategy alter knee total joint moment during bipedal ambulatory tasks in recruit-aged women. J Biomech 2020; 105:109772. [PMID: 32279931 DOI: 10.1016/j.jbiomech.2020.109772] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/09/2020] [Accepted: 03/28/2020] [Indexed: 10/24/2022]
Abstract
Knee osteoarthritis (OA) is prevalent among female soldiers, resulting in limited duty and long term adverse ambulatory effects. A proposed mechanism to the development of knee OA is the assiduous execution of load carriage tasks. Soldiers are often required to maintain a walking gait with load at velocities beyond their gait transition velocity (GTV) known as forced marching. The primary aim of this investigation is to determine the interactive effects of load magnitude and locomotion pattern on relative knee total joint moment (KTJM) in healthy recruit-aged women. The secondary aims are to determine knee total joint moment limb differences and to determine the interactive effect of load magnitude and locomotion pattern on the percent contributions of each plane of motion moment. Individuals were tasked with running and forced marching at 10% above their GTV at body weight (BW) and with an additional 25% and 45% of their BW. KTJM was analyzed at two specific gait events of heel-strike and mid-stance. At heel-strike, forced marching exhibited greater KTJM compared to run for all load conditions but running had greater KTJM than forced marching at mid-stance. The forced marching pattern exhibited larger KTJM for the dominant limb at both gait events compared to running. Lastly, at mid-stance the knee adduction moment percent (KAM%) contribution was greater for forced marching compared to running. The forced marching pattern demonstrates joint kinetics that may be more deleterious with prolonged exposure. Likewise, forced marching induced KAM% similar to those already suffering from knee OA.
Collapse
|
65
|
Johnson CD, Eagle SR, Nindl BC, Lovalekar MT, Flanagan SD, Pepping GJ, Connaboy C. The effects of fatiguing exercise and load carriage on the perception and initiation of movement. Eur J Sport Sci 2020; 21:36-44. [PMID: 32013782 DOI: 10.1080/17461391.2020.1725137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Perceptual-motor coordination relies on the accurate coupling of the perceptual and movement systems. However, individuals must also be able to recalibrate to perturbations to perceptual and movement capabilities. We examined the effects of fatigue and load carriage on perceptual-motor coordination for a maximal leaping task. 23 participants completed an incremental fatigue protocol (light to fatiguing intensity stages) on two separate occasions (loaded/unloaded). At baseline and the end of every stage of the protocol, participants made perceptual judgments for the affordance of leaping. The accuracy of responses and reaction times were calculated and mean differences were assessed across exercise intensity and load carriage conditions. No interaction of exercise intensity and load carriage was detected, or main effect of load carriage. A main, quadratic effect of exercise intensity was detected on reaction times, with times decreasing through the moderate stage and increasing through post-fatigue. No effect of exercise/fatigue was detected on perceptual accuracy. The results indicate that exercise at high intensities through fatigue has a significant effect on perceptual-motor calibration. Contrastingly, in response to an action-scaled task, individuals can adequately recalibrate to increased load carriage.
Collapse
|
66
|
LaGoy AD, Johnson C, Allison KF, Flanagan SD, Lovalekar MT, Nagai T, Connaboy C. Compromised Dynamic Postural Stability Under Increased Load Carriage Magnitudes. J Appl Biomech 2020; 36:27-32. [PMID: 31914419 DOI: 10.1123/jab.2018-0473] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 10/30/2019] [Accepted: 11/06/2019] [Indexed: 11/18/2022]
Abstract
Warfighter performance may be compromised through the impact of load carriage on dynamic postural stability. Men and women may experience this impact to differing extents due to postural stability differences. Therefore, the authors investigated the effect of load magnitude on dynamic postural stability in men and women during a landing and stabilization task. Dynamic postural stability of 32 subjects (16 women) was assessed during the unilateral landing of submaximal jumps under 3 load conditions: +0%, +20%, and +30% body weight. Dynamic postural stability was measured using the dynamic postural stability index, which is calculated from ground reaction force data sampled at 1200 Hz. Two-way mixed-measures analysis of variance compared dynamic postural stability index scores between sexes and loads. Dynamic postural stability index scores were significantly affected by load (P = .001) but not by sex or by the sex by load interaction (P > .05). Dynamic postural stability index scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034), and 30% (0.420 ± 0.028) body weight conditions. Increased load negatively affects dynamic postural stability with similar performance decrements displayed by men and women. Men and women warfighters may experience similar performance decrements under load carriage conditions of similar relative magnitudes.
Collapse
|
67
|
Bowie J, Sterczala AJ, Kraemer WJ, Maresh CM, Comstock BA, Flanagan SD, Szivak TK, Hooper DR, Lee EC. Acute Heavy Resistance Exercise Protocol Induces Significant Physiological Stress Elevating Extracellular Heat Shock Protein. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000562886.89657.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
68
|
Eagle S, Mi Q, Kontos AP, Flanagan SD, Nindl BC, Beals K, Connaboy C. Leveraging Machine Learning Techniques to Reveal Relationships between Neuromuscular Traits in Previously Concussed Warfighters. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561337.28241.c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
69
|
Sterczala AJ, Dunn-Lewis C, Proessl F, Beethe AZ, Nindl BC, Kraemer WJ, Flanagan SD. Persistent Reductions in Strength of Sensorimotor Circuits Governing Injured Leg After ACL Rupture. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561292.05439.50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
70
|
Proessl F, Beethe AZ, Sterczala AJ, Dunn-Lewis C, Connaboy C, Nindl BC, Flanagan SD. Altered Brain Morphology In Women With History Of ACL Rupture: A Structural MRI Study. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000561291.97815.bb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
71
|
Beckner ME, Martin BJ, Pihoker AA, Darnell ME, Kjellsen AL, Arciero PJ, Lovalekar MT, Beals K, Flanagan SD, Nindl BC. The Effects of Two Multi-Ingredient Pre-Workout Supplements on Endurance Capacity and Anaerobic Cycling Performance. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000560911.75489.d0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
72
|
Eagle SR, Kessels M, Johnson CD, Nijst B, Lovalekar M, Krajewski K, Flanagan SD, Nindl BC, Connaboy C. Bilateral Strength Asymmetries and Unilateral Strength Imbalance: Predicting Ankle Injury When Considered With Higher Body Mass in US Special Forces a. J Athl Train 2019; 54:497-504. [PMID: 31074634 DOI: 10.4085/1062-6050-255-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
CONTEXT Ankle injury is one of the most common conditions in athletics and military activities. Strength asymmetry (SA) and imbalance may represent a risk factor for injury, but past investigations have produced ambiguous conclusions. Perhaps one explanation for this ambiguity is the fact that these authors used univariate models to predict injury. OBJECTIVE To evaluate the predictive utility of SA and imbalance calculations for ankle injury in univariate and multivariate prediction models. DESIGN Prospective cohort study. SETTING Laboratory. PATIENTS OR OTHER PARTICIPANTS A total of 140 male US Air Force Special Forces. MAIN OUTCOME MEASURE(S) Baseline testing consisted of body composition, isometric strength, and aerobic and anaerobic capacity. A clinician conducted medical chart reviews 365 days posttesting to document the incidence of ankle injury. Strength asymmetries were calculated based on the equations most prevalent in the literature along with known physiological predictors of injury in the military: age, height, weight, body composition, and aerobic capacity. Simple logistic regression was conducted using each predictor, and backward stepwise logistic regression was conducted with each equation method and the physiological predictors entered initially into the model. RESULTS Strength asymmetry or imbalance or both, as a univariate predictor, was not able to predict ankle injury 365 days posttesting. Body mass (P = .01) and body mass index (P = .01) significantly predicted ankle injury. Strength asymmetry or imbalance or both significantly predicted ankle injury when considered with body mass (P = .002-.008). CONCLUSIONS As a univariate predictor, SA did not predict ankle injury. However, SA contributed significantly to predicting ankle injury in a multivariate model using body mass. Interpreting SA and imbalance in the presence of other physiological variables can help elucidate the risk of ankle injury.
Collapse
|
73
|
Johnson CD, Nijst BKJF, Eagle SR, Kessels MWM, Lovalekar MT, Krajewski KT, Flanagan SD, Nindl BC, Connaboy C. Evaluation of Shoulder Strength and Kinematics as Risk Factors for Shoulder Injury in United States Special Forces Personnel. Orthop J Sports Med 2019; 7:2325967119831272. [PMID: 30891463 PMCID: PMC6416681 DOI: 10.1177/2325967119831272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background Musculoskeletal injuries at the shoulder are highly prevalent and place a large burden on United States Special Forces personnel. Literature is lacking regarding the risk factors for these types of injuries. Purpose/Hypothesis The purpose of this study was to evaluate the association of shoulder strength and kinematic characteristics, which have shown retrospective associations with shoulder conditions/injuries, with prospectively collected shoulder injuries. We hypothesized that lower strength and abnormal kinematics would be predictive of future shoulder injury. Study Design Case-control study; Level of evidence, 3. Methods A total of 140 male Special Forces operators underwent a musculoskeletal evaluation of the shoulder that included a scapular kinematic assessment during a humeral elevation task and isokinetic strength testing of the scapular protractors/retractors, external/internal rotators, and elevators of the shoulder. From strength assessments, ipsilateral strength ratios and bilateral strength asymmetries were also calculated. Musculoskeletal injuries of the shoulder were collected prospectively by use of medical chart reviews at 365 days following the evaluation. Separate generalized estimating equations (GEEs) and simple logistic regressions were used to analyze the association between baseline predictors and development of shoulder injury. Results Results of the GEEs showed no significant prediction of shoulder injury by shoulder strength (odds ratio [OR], 1.00-1.03), ipsilateral strength ratios (OR, 0.43-2.12), or scapular kinematics (OR, 0.99-1.01). Logistic regression indicated that none of the bilateral asymmetries were significantly predictive of shoulder injury (OR, 1.00-1.04). Conclusion The results indicate that shoulder strength and kinematic characteristics are not risk factors for shoulder injury in the Special Forces population. These findings are in opposition to the general findings of previous research using a retrospective analysis.
Collapse
|
74
|
Eagle SR, Kontos AP, Mi QI, Flanagan SD, Nindl BC, Beals K, Connaboy C. Shared Neuromuscular Performance Traits in Military Personnel with Prior Concussion. Med Sci Sports Exerc 2019; 51:1619-1625. [PMID: 30845049 DOI: 10.1249/mss.0000000000001974] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Concussions are common in military personnel and may result in increased risk of musculoskeletal injury. One plausible explanation for this risk could be that neuromotor deficiencies enhance injury risk after a concussion through altered muscular activation/contraction timing. PURPOSE To compare military personnel with at least one concussion during the past 1 month to 2 yr (CONCUSSED) to military branch-matched, age-matched, and Special Operations Forces group-matched controls (CONTROL) on physiological, musculoskeletal, and biomechanical performance. METHODS A total of 48 (24 CONCUSSED, 24 CONTROL) male Air Force and Naval Special Warfare Operators age 19 to 34 yr participated in the study. Participants self-reported demographics/injury history and completed the following assessments: 1) physiological-body composition, anaerobic power and capacity, aerobic capacity and lactate threshold; 2) musculoskeletal-lower extremity isokinetic strength testing, including time to peak torque; and 3) biomechanical-single-leg jump and landing task, including landing kinematics of the hip, knee and ankle. A machine learning decision tree algorithm (C5.0) and one-way ANOVA were used to compare the two groups on these outcomes. RESULTS Despite nonsignificant differences using ANOVA, the C5.0 algorithm revealed CONCUSSED demonstrated quicker time to peak knee flexion angle during the single-leg landing task (≤0.170 s; CONCUSSED: n = 22 vs CONTROL: n = 14), longer time to peak torque in knee extension isokinetic strength testing (>500 ms; CONCUSSED: n = 18 vs CONTROL: n = 4) and larger knee flexion angle at initial contact (>7.7°; CONCUSSED: n = 18 vs CONTROL: n = 2). CONCLUSION The findings supported the hypothesis that CONCUSSED military personnel would demonstrate altered neuromuscular control in landing strategies and muscular activation. Future research should assess prospectively neuromuscular changes after a concussion and determine if these changes increase risk of subsequent musculoskeletal injuries.
Collapse
|
75
|
Flanagan SD, Beethe AZ, Eagle SR, Proessl F, Connaboy C, Dunn-Lewis C, Kraemer WJ. Blinding success of sham-controlled motor cortex intermittent theta burst stimulation based on participant perceptions. Brain Stimul 2019; 12:1058-1060. [PMID: 30871844 DOI: 10.1016/j.brs.2019.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 03/04/2019] [Indexed: 10/27/2022] Open
|
76
|
Johnson CD, Beethe AZ, Eagle SR, Mi Q, Lovalekar MT, Pepping G, Nindl BC, Flanagan SD, Connaboy C. Profiles of mood state fatigue scale is responsive to fatiguing protocol but shows no relationship to perceived or performance decrements. TRANSLATIONAL SPORTS MEDICINE 2019. [DOI: 10.1002/tsm2.65] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
77
|
Connaboy C, Johnson CD, LaGoy AD, Pepping GJ, Simpson RJ, Deng Z, Ma L, Bower JL, Eagle SR, Flanagan SD, Alfano CA. Intersession Reliability and Within-Session Stability of a Novel Perception-Action Coupling Task. Aerosp Med Hum Perform 2019; 90:77-83. [PMID: 30670116 DOI: 10.3357/amhp.5190.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND: The perception-action coupling task (PACT) was designed as a more ecologically valid measure of alertness/reaction times compared to currently used measures by aerospace researchers. The purpose of this study was to assess the reliability, within-subject variability, and systematic bias associated with the PACT.METHODS: There were 16 subjects (men/women = 9 / 7; age = 27.8 ± 3.6 yr) who completed 4 identical testing sessions. The PACT requires subjects to make judgements on whether a virtual ball could fit into an aperture. For each session, subjects completed nine cycles of the PACT, with each cycle lasting 5 min. Judgement accuracy and reaction time parameters were calculated for each cycle. Systematic bias was assessed with repeated-measures ANOVA, reliability with intraclass correlation coefficients (ICC), and within-subject variability with coefficients of variation (CVTE).RESULTS: Initiation time (Mean = 0.1065 s) showed the largest systematic bias, requiring the elimination of three cycles to reduce bias, with all other variables requiring, at the most, one. All variables showed acceptable reliability (ICC > 0.70) and within-subject variability (CVTE < 20%) with only one cycle after elimination of the first three cycles.CONCLUSIONS: With a three-cycle familiarization period, the PACT was found to be reliable and stable.Connaboy C, Johnson CD, LaGoy AD, Pepping G-J, Simpson RJ, Deng Z, Ma L, Bower JL, Eagle SR, Flanagan SD, Alfano CA. Intersession reliability and within-session stability of a novel perception-action coupling task. Aerosp Med Hum Perform. 2019; 90(2):77-83.
Collapse
|
78
|
Flanagan SD, Krajewski KT, Sinnott AM, Johnson CD, Eagle SR, LaGoy AD, Beckner ME, Beethe AZ, Turner R, Lovalekar MT, Dunn-Lewis C, Connaboy C, Nindl BC. Prediction of exertional lower extremity musculoskeletal injury in tactical populations: protocol for a systematic review and planned meta-analysis of prospective studies from 1955 to 2018. Syst Rev 2018; 7:244. [PMID: 30580762 PMCID: PMC6304230 DOI: 10.1186/s13643-018-0883-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 11/13/2018] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Musculoskeletal injuries (MSI) represent more than half of all injuries in tactical populations (i.e., military service and public safety workers including police, firefighters, emergency medical services (EMS)). Most lower extremity MSIs result from physical exertion during training, occupational tasks, and recreation. Such exertional lower extremity injuries (ELEI) produce a significant human and financial cost. Accordingly, significant efforts have been made to identify sensitive, specific, and reliable predictors of ELEI. There is a need to synthesize and evaluate the predictive value of risk factors for ELEI while addressing the influence of occupation, sex, exposure, injury characteristics, and study quality. Therefore, the purpose of this systematic review and planned meta-analysis is to evaluate risk factors for ELEI in tactical populations. METHODS After the development of a search strategy, comprehensive searches will be conducted in MEDLINE, EMBASE, Cochrane, and CINAHL databases. Articles will be screened with a multi-user process and delimited to prospective comparative cohort studies that directly measure injury occurrence in the target population(s). Extracted data will be synthesized and assessed for reporting bias, meta-bias, and overall quality, with subgroup analyses to determine the influence of participant, injury, and exposure characteristics in addition to study quality. DISCUSSION This systematic review and planned meta-analysis will comprehensively evaluate ELEI risk factors. Information gained will inform injury prevention protocols, facilitate the use of improved measurements, and identify requirements for future research. TRIAL REGISTRATION The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018056977 ).
Collapse
|
79
|
Flanagan SD, Sinnott AM, Krajewski KT, Johnson CD, Eagle SR, LaGoy AD, Beckner ME, Beethe AZ, Turner R, Lovalekar M, Dunn-Lewis C, Connaboy C, Nindl BC. Prevention of exertional lower body musculoskeletal injury in tactical populations: protocol for a systematic review and planned meta-analysis of prospective studies from 1955 to 2018. Syst Rev 2018; 7:73. [PMID: 29729666 PMCID: PMC5936627 DOI: 10.1186/s13643-018-0730-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 04/13/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Exertional lower body musculoskeletal injuries (ELBI) cost billions of dollars and compromise the readiness and job performance of military service and public safety workers (i.e., tactical populations). The prevalence and burden of such injuries underscores the importance of prevention efforts during activities necessary to sustain core occupational competencies. Attempts to synthesize prevention techniques specific to tactical populations have provided limited insight on the comparative efficacy of interventions that do not modify physical training practices. There is also a need to assess the influence of sex, exposure, injury classification scheme, and study design. Thus, the primary purpose of the systematic review and planned meta-analysis detailed in this protocol is to evaluate the comparative efficacy of ELBI prevention strategies in tactical populations. METHODS A systematic search strategy will be implemented in MEDLINE, EMBASE, Cochrane, and CINAHL. A multi-tiered process will be used to capture randomized controlled trials and prospective cohort studies that directly assess the prevention of ELBI in tactical population(s). Extracted data will be used to compare prevention strategies and assess the influence of heterogeneity related to occupation, sex, exposure, injury characteristics, and study quality. In addition, individual risk of bias, meta-bias, and the quality of the body of evidence will be rigorously tested. DISCUSSION This systematic review and planned meta-analysis will comprehensively evaluate ELBI mitigation strategies in tactical populations, elucidate factors that influence responses to treatment, and assess the overall quality of the body of research. Results of this work will guide the prioritization of ELBI prevention strategies and direct future research efforts, with direct relevance to tactical, health and rehabilitation science, and human performance optimization stakeholders. SYSTEMATIC REVIEW REGISTRATION The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018081799 ).
Collapse
|
80
|
Dunn-Lewis C, Flanagan SD. Bilateral Training Results in Superior Strength Improvements to Unilateral Despite Similar Changes in Fat-Free Mass. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000537242.94935.91] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
81
|
Martin BJ, Beckner ME, Sowa GA, Schneider MJ, Flanagan SD, Dunn‐Lewis C, Poropatich R, Nindl BC. Effects of the Insulin‐like Growth Factor Axis and its Relationship in Nonsurgical Treatments in Patients with Lumbar Spinal Stenosis. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.588.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
82
|
Szivak TK, Lee EC, Saenz C, Flanagan SD, Focht BC, Volek JS, Maresh CM, Kraemer WJ. Adrenal Stress and Physical Performance During Military Survival Training. Aerosp Med Hum Perform 2018; 89:99-107. [PMID: 29463354 DOI: 10.3357/amhp.4831.2018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
INTRODUCTION The purpose of this research was to evaluate neuroendocrine and physical performance responses in sailors and Marines undergoing U.S. Navy Survival, Evasion, Resistance, and Escape (SERE) training. METHODS Participants were 20 men (Age: 25.3 ± 3.6 yr; Height: 178.1 ± 6.1 cm; Weight: 83.7 ± 12.6 kg). Men were further split into high fit (N = 10) and low fit (N = 10) subgroups based on physical fitness test scores. Blood samples were obtained at baseline (T1), stress (T2), and recovery (T3) timepoints, and were analyzed for plasma epinephrine, plasma norepinephrine, plasma dopamine, serum cortisol, serum testosterone, and plasma neuropeptide Y. Vertical jump and handgrip tests were performed at T1 and T2. RESULTS Stress hormone concentrations were significantly elevated at T2, with a concomitant reduction in testosterone concentrations. NPY concentrations did not increase at T2, but decreased significantly at T3. Subjects maintained performance on vertical jump and handgrip tests from T1 to T2. Significant between group differences were observed in norepinephrine (high fit: 3530.64 ± 2146.54 pmol · L-1, low fit: 4907.16 ± 3020.85 pmol · L-1) and NPY (high fit: 169.30 ± 85.89 pg · ml-1, low fit: 123.02 ± 88.86 pg · ml-1) concentrations at T3. CONCLUSION This study revealed that despite significant increases in stress hormone concentrations in all subjects during SERE, fitter subjects exhibited differential hormonal responses during recovery, with quicker return of norepinephrine and NPY to baseline concentrations. This suggests physical fitness level may have a protective effect in recovery from periods of high stress military training.Szivak TK, Lee EC, Saenz C, Flanagan SD, Focht BC, Volek JS, Maresh CM, Kraemer WJ. Adrenal stress and physical performance during military survival training. Aerosp Med Hum Perform. 2018; 89(2):99-107.
Collapse
|
83
|
Flanagan SD, Minassian SL, Prokocimer P. Pharmacokinetics, Safety, and Tolerability of Tedizolid Phosphate in Elderly Subjects. Clin Pharmacol Drug Dev 2018; 7:788-794. [DOI: 10.1002/cpdd.426] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 11/08/2017] [Indexed: 12/12/2022]
|
84
|
Flanagan SD, DuPont WH, Caldwell LK, Hardesty VH, Barnhart EC, Beeler MK, Post EM, Volek JS, Kraemer WJ. The Effects of a Korean Ginseng, GINST15, on Hypo-Pituitary-Adrenal and Oxidative Activity Induced by Intense Work Stress. J Med Food 2018; 21:104-112. [DOI: 10.1089/jmf.2017.0071] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
|
85
|
Kraemer WJ, Kennett MJ, Mastro AM, McCarter RJ, Rogers CJ, DuPont WH, Flanagan SD, Turbitt WJ, Fragala MS, Post EM, Hymer WC. Bioactive growth hormone in older men and women: It's relationship to immune markers and healthspan. Growth Horm IGF Res 2017; 34:45-54. [PMID: 28551577 DOI: 10.1016/j.ghir.2017.05.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/07/2017] [Accepted: 05/07/2017] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The consequences of age-related decline in the somatotropic axis of humans are complex and remain largely unresolved. We tested the hypothesis that hGH measurements of plasma by bioassay vs immunoassay from samples obtained from free-living, elderly individuals would reveal a dichotomy in GH activities that are correlated with the functional status of the donors, i.e. their healthspan. DESIGN Forty-one men and women of advanced age (men: N=16, age, 80.5±6.5years; height, 173.1±6.9cm; body mass, 81.8±13.0kg) and (women: N=25, age, 80.7±7.2years; height, 157.7±6.0cm; body mass, 68.8±17kg), were recruited for a cross-sectional study. Participants filled out PROMIS (Patient-Reported Outcomes Measurement Information System, U. S. Department of Health and Human Services) scales, undertook physical performance tests and had fasted blood samples obtained at rest for measurement of hormonal and immunology biomarkers. RESULTS When measured by the well-established rat tibial line GH bioassay, one half of the plasma samples (n=20) contained bioassayable GH (bGH), but the other half (n=21) failed to mount increases in tibial plate width above saline injected controls. This difference did not correlate with the age, sex or physical functionality of the plasma donor. It also did not correlate with hGH concentrations measured by immunoassay. In those cases in which bGH was detected, various hierarchical regression models predicted that GHRH, c-peptide, VEGF, NPY, IL-4 and T-regulatory lymphocytes were associated with the difference and predicted bGH. CONCLUSION Results from this study suggest that the actions of bGH at the cellular level may be modified by other factors and that this may explain the lack of correlations observed in this study.
Collapse
|
86
|
Dunn-Lewis C, Flanagan SD, Onate JA, Volek JS, Maresh CM, Kraemer WJ. Injury-Related Reductions in Skilled Visuomotor Learning Revealed by Single Trial Analysis and Response Time Variability. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000517442.65878.bd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
87
|
Flanagan SD, Dunn-Lewis C, Onate JA, Volek JS, Maresh CM, Kraemer WJ. Unique Leg-specific Executive And Motor BOLD Activity With Visually-guided Imagery Following ACL Injury. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000517443.73501.82] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
88
|
Le VTM, Le HN, Pinheiro MG, Hahn KJ, Dinh ML, Larson KB, Flanagan SD, Badiou C, Lina G, Tkaczyk C, Sellman BR, Diep BA. Effects of Tedizolid Phosphate on Survival Outcomes and Suppression of Production of Staphylococcal Toxins in a Rabbit Model of Methicillin-Resistant Staphylococcus aureus Necrotizing Pneumonia. Antimicrob Agents Chemother 2017; 61:e02734-16. [PMID: 28137816 PMCID: PMC5365717 DOI: 10.1128/aac.02734-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 01/24/2017] [Indexed: 01/30/2023] Open
Abstract
The protective efficacy of tedizolid phosphate, a novel oxazolidinone that potently inhibits bacterial protein synthesis, was compared to those of linezolid, vancomycin, and saline in a rabbit model of Staphylococcus aureus necrotizing pneumonia. Tedizolid phosphate was administered to rabbits at 6 mg/kg of body weight intravenously twice daily, which yielded values of the 24-h area under the concentration-time curve approximating those found in humans. The overall survival rate was 83% for rabbits treated with 6 mg/kg tedizolid phosphate twice daily and 83% for those treated with 50 mg/kg linezolid thrice daily (P = 0.66 by the log-rank test versus the results obtained with tedizolid phosphate). These survival rates were significantly greater than the survival rates of 17% for rabbits treated with 30 mg/kg vancomycin twice daily (P = 0.003) and 17% for rabbits treated with saline (P = 0.002). The bacterial count in the lungs of rabbits treated with tedizolid phosphate was significantly decreased compared to that in the lungs of rabbits treated with saline, although it was not significantly different from that in the lungs of rabbits treated with vancomycin or linezolid. The in vivo bacterial production of alpha-toxin and Panton-Valentine leukocidin, two key S. aureus-secreted toxins that play critical roles in the pathogenesis of necrotizing pneumonia, in the lungs of rabbits treated with tedizolid phosphate and linezolid was significantly inhibited compared to that in the lungs of rabbits treated with vancomycin or saline. Taken together, these results indicate that tedizolid phosphate is superior to vancomycin for the treatment of S. aureus necrotizing pneumonia because it inhibits the bacterial production of lung-damaging toxins at the site of infection.
Collapse
|
89
|
Looney DP, Kraemer WJ, Joseph MF, Comstock BA, Denegar CR, Flanagan SD, Newton RU, Szivak TK, DuPont WH, Hooper DR, Häkkinen K, Maresh CM. Electromyographical and Perceptual Responses to Different Resistance Intensities in a Squat Protocol: Does Performing Sets to Failure With Light Loads Produce the Same Activity? J Strength Cond Res 2016; 30:792-9. [PMID: 26270694 DOI: 10.1519/jsc.0000000000001109] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This investigation examined peak motor unit activity during sets that differed in resistance (50, 70, or 90% 1 repetition maximum [1RM]). Ten resistance-trained men (age, 23 ± 3 years; height, 187 ± 7 cm; body mass, 91.5 ± 6.9 kg; squat 1RM, 141 ± 28 kg) were assessed by electromyography (EMG) on the vastus lateralis and vastus medialis muscles in a randomized within-subject experiment consisting of 2 test visits: a drop-set day and a single-set day using only the 50% of 1RM intensity performed to failure. At the start of each day, subjects performed 2 submaximal repetition sets (50% 1RM × 10 repetitions and 70% 1RM × 7 repetitions). On the drop-set day, subjects performed 3 consecutive maximal repetition sets at 90%, 70%, and 50% 1RM to failure with no rest periods in between. On the single-set day, subjects performed a maximal repetition set at 50% 1RM to failure. Overall, the maximal repetition sets to failure at 50% and 70% 1RM resulted in higher peak EMG amplitude than during submaximal repetition sets with the same resistance. However, peak EMG amplitude was significantly (p ≤ 0.05) greater in the maximal 90% 1RM set than all other sets performed. When sets were performed to failure, ratings of perceived exertion (CR-10) did not differ over the intensity range of loads and suggests that perception is not capable of accurately detecting the actual amount of motor unit activation. The results of this investigation indicate that using higher external resistance is a more effective means of increasing motor unit activity than increasing the number of repetitions performed with lighter weights even when the end point is muscular failure. Accordingly, previous recommendations for the use of heavier loads during resistance training programs to stimulate the maximal development of strength and hypertrophy are further supported.
Collapse
|
90
|
Sterczala AJ, DuPont WH, Comstock BA, Flanagan SD, Szivak TK, Hooper DR, Kupchak BR, Lee EC, Volek JS, Maresh CM, Kraemer WJ. Physiological Effects of Nucleotide Supplementation on Resistance Exercise Stress in Men and Women. J Strength Cond Res 2016; 30:569-78. [PMID: 26270693 DOI: 10.1519/jsc.0000000000001108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nucleotide supplementation can reduce postexercise immunosuppression and hypothalamic-pituitary axis (HPA) axis activation in endurance exercise models. Nucleotide supplementation may aid recovery from other exercise modalities, such as heavy resistance exercise. Thus, the purpose of this investigation was to investigate the effects of nucleotide supplementation on the acute cortisol and immune responses to heavy resistance exercise and its effects on recovery. A double-blinded, crossover, mixed methods design with 10 men and 10 women was used. Each performed an acute heavy resistance exercise protocol (AHREP) after a loading period with a nucleotide or placebo supplement. Before and after the AHREP, and at 24, 48, and 72 hours post, blood samples were analyzed for cortisol, myeloperoxidase (MPO), and absolute neutrophil, lymphocyte, and monocyte counts. Creatine kinase (CK) was analyzed before and 24, 48, and 72 hours after the AHREP. Performance measures, including peak back squat isometric force and peak countermovement jump power were also analyzed. Nucleotide supplementation resulted in significant (p ≤ 0.05) decreases in cortisol and MPO immediately after the AHREP, and significantly lower CK values 24 hours later. The AHREP significantly affected leukocyte counts; however, no treatment effects were observed. Greater isometric force was observed immediately after AHREP and at 24 hours and 48 hours with nucleotide supplementation. Nucleotide supplementation seems to attenuate muscle damage, HPA axis and immune system activation, and performance decrements after heavy resistance exercise.
Collapse
|
91
|
Lodise TP, Bidell MR, Flanagan SD, Zasowski EJ, Minassian SL, Prokocimer P. Characterization of the haematological profile of 21 days of tedizolid in healthy subjects. J Antimicrob Chemother 2016; 71:2553-8. [DOI: 10.1093/jac/dkw206] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 05/03/2016] [Indexed: 01/28/2023] Open
|
92
|
Kraemer WJ, Hooper DR, Kupchak BR, Saenz C, Brown LE, Vingren JL, Luk HY, DuPont WH, Szivak TK, Flanagan SD, Caldwell LK, Eklund D, Lee EC, Häkkinen K, Volek JS, Fleck SJ, Maresh CM. The effects of a roundtrip trans-American jet travel on physiological stress, neuromuscular performance, and recovery. J Appl Physiol (1985) 2016; 121:438-48. [PMID: 27283914 DOI: 10.1152/japplphysiol.00429.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/08/2016] [Indexed: 11/22/2022] Open
Abstract
The purpose was to examine the effects of a round trip trans-American jet travel on performance, hormonal alterations, and recovery. Ten matched pairs of recreationally trained men were randomized to either a compression group (COMP) (n = 10; age: 23.1 ± 2.4 yr; height: 174.8 ± 5.3 cm; body mass: 84.9 ± 10.16 kg; body fat: 15.3 ± 6.0%) or control group (CONT) (n = 9; age: 23.2 ± 2.3 yr; height: 177.5 ± 6.3 cm; weight: 84.3 ± 8.99 kg; body fat: 15.1 ± 6.4%). Subjects flew directly from Hartford, CT to Los Angeles, CA 1 day before a simulated sport competition (SSC) designed to create muscle damage and returned the next morning on an overnight flight back home. Both groups demonstrated jet lag symptoms and associated decreases in sleep quality at all time points. Melatonin significantly (P < 0.05) increased over the first 2 days and then remained constant until after the SSC. Epinephrine, testosterone, and cortisol values significantly increased above resting values before and after the SSC with norepinephrine increases only after the SSC. Physical performances significantly decreased from control values on each day for the CONT group with COMP group exhibiting no significant declines. Muscle damage markers were significantly elevated following the SSC with the COMP group having significantly lower values while maintaining neuromuscular performance measures that were not different from baseline testing. Trans-American jet travel has a significant impact on parameters related to jet lag, sleep quality, hormonal responses, muscle tissue damage markers, and physical performance with an attenuation observed with extended wear compression garments.
Collapse
|
93
|
Hooper DR, Schill KE, Saenz C, Martini ER, Flanagan SD, Szivak TK, DuPont WH, Focht BC, Volek JS, Maresh CM, Kraemer WJ. Pathogenesis And Symptomology Of The Exercise-hypogonodal Male Condition. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000488086.72956.7b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
94
|
DuPont WH, Kraemer WJ, Nindl BC, Vingren JL, Spiering BA, Flanagan SD, Caldwell LK, Szivak TK, Barnhart EC, Borden EC, Maresh CM. The Influence of Different Training Programs on the Expression of Plasma Proenkephalin Peptide F in Women. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000485435.56423.2c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
95
|
Flanagan SD, Szivak TK, DuPont WH, Caldwell LK, Barnhart EC, Borden EC, Saenz C, Staron RS, Hymer WC, Nindl BC, Kraemer WJ. Comparing Bioactive And Immunoassay-Based Measurements Of The Growth Hormone Response To Short-Term Resistance Training At Three Intensity Levels. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000486898.76467.68] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
96
|
Ortiz-Covarrubias A, Fang E, Prokocimer PG, Flanagan SD, Zhu X, Cabré-Márquez JF, Tanaka T, Passarell J, Fiedler-Kelly J, Nannini EC. Efficacy, safety, tolerability and population pharmacokinetics of tedizolid, a novel antibiotic, in Latino patients with acute bacterial skin and skin structure infections. Braz J Infect Dis 2016; 20:184-92. [PMID: 26859064 PMCID: PMC9427544 DOI: 10.1016/j.bjid.2015.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 12/28/2015] [Indexed: 12/18/2022] Open
|
97
|
Flanagan SD, Looney DP, Miller MJS, DuPont WH, Pryor L, Creighton BC, Sterczala AJ, Szivak TK, Hooper DR, Maresh CM, Volek JS, Ellis LA, Kraemer WJ. The Effects of Nitrate-Rich Supplementation on Neuromuscular Efficiency during Heavy Resistance Exercise. J Am Coll Nutr 2016; 35:100-7. [DOI: 10.1080/07315724.2015.1081572] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
98
|
Hooper DR, Cook BM, Comstock BA, Szivak TK, Flanagan SD, Looney DP, DuPont WH, Kraemer WJ. Synthetic garments enhance comfort, thermoregulatory response, and athletic performance compared with traditional cotton garments. J Strength Cond Res 2016; 29:700-7. [PMID: 25463694 DOI: 10.1519/jsc.0000000000000783] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ability of a fabric to transfer moisture is referred to as "wicking," and an increase in this property may have benefits in terms of comfort and thermoregulation. However, this phenomenon has not been studied in the context of sporting-type activities. Therefore, the purpose of this study is to assess whether comfort, thermal physiological parameters, and physical performance can be affected by the garment that is used. Ten men (age: 27.5 ± 4.4 years; height: 169.3 ± 14.2 cm; weight: 80.05 ± 10.87 kg) and 10 women (age: 26.8 ± 3.7 years; height: 166.6 ± 4.46 cm; weight: 64.63 ± 4.49 kg) volunteered to participate in the study. A within-group crossover counterbalanced design was used that included the Illinois Agility Run (IAR) and the Multistage Fitness Test (MSFT). The IAR was also performed while wearing protective padding. The protocol was completed on 2 occasions, once while wearing a cotton garment (C) and again while wearing a polyester (P) garment. Questionnaires referring to sensations of various components of comfort were completed after each test. The P garment provided significantly (p ≤ 0.05) greater comfort in men and women after both the IAR and the MSFT. The P garment led to significantly (p ≤ 0.05) improved performance during the IAR in women. The P garment also provided significantly (p ≤ 0.05) greater body mass loss during the protocol in women. This study demonstrated dramatic increases in the comfort of P garments, including while using protective equipment. This study also discovered the influence of P garments on anaerobic tasks and also revealed dramatic sex differences, where women seem to be much more sensitive to the benefits of P garments. Strength and conditioning coaches should be aware of the dramatic impact of garment choice, in aerobic and anaerobic tasks, particularly in women.
Collapse
|
99
|
Sterczala AJ, Flanagan SD, Looney DP, Hooper DR, Szivak TK, Comstock BA, DuPont WH, Martin GJ, Volek JS, Maresh CM, Kraemer WJ. Similar hormonal stress and tissue damage in response to National Collegiate Athletic Association Division I football games played in two consecutive seasons. J Strength Cond Res 2016; 28:3234-8. [PMID: 25148465 DOI: 10.1519/jsc.0000000000000467] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The recovery process from a college football game has been studied, yet the stability of such findings year to year in the same players remains unclear. The purpose of this study was to examine the same players' biochemical recovery process in 2 consecutive seasons to a National Collegiate Athletic Association (NCAA) Division I football game. Ten starting players volunteered to participate in the study in each of the 2 seasons. Players performed a periodized heavy resistance training program over the entire year for each season. Fasted resting blood samples were obtained at similar times the Friday before the game (T1), 18-20 hours after the game (T2), and 42-44 hours after the game (T3). In both seasons, serum creatine kinase (CK) concentrations increased significantly from T1 to T2, and returned to T1 values at T3. When we compared seasons, CK values did not differ at any time point. Myoglobin demonstrated similar patterns and results. Testosterone and cortisol values were similar at all time points and did not differ by season as no significant differences were observed for the resting hormonal concentrations. The results of this study indicate that yearly programs should maintain a periodized progressive program, which seeks to increase physical potential of players while providing a protective effect on skeletal muscle and stabilization of hormonal status in response to both game and season stressors.
Collapse
|
100
|
Flanagan SD, Dunn-Lewis C, Hatfield DL, Distefano LJ, Fragala MS, Shoap M, Gotwald M, Trail J, Gomez AL, Volek JS, Cortis C, Comstock BA, Hooper DR, Szivak TK, Looney DP, DuPont WH, McDermott DM, Gaudiose MC, Kraemer WJ. Developmental differences between boys and girls result in sex-specific physical fitness changes from fourth to fifth grade. J Strength Cond Res 2015; 29:175-80. [PMID: 25187248 DOI: 10.1519/jsc.0000000000000623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To better understand how developmental differences impact performance on a broad selection of common physical fitness measures, we examined changes in boys and girls from fourth to fifth grade. Subjects included 273 boys (age, 9.5 ± 0.6 years; height, 139.86 ± 7.52 cm; mass, 38.00 ± 9.55 kg) and 295 girls (age, 9.6 ± 0.5 years; height, 139.30 ± 7.19 cm; weight, 37.44 ± 9.35 kg). We compared anthropometrics, cardiorespiratory and local muscular endurance, flexibility, power, and strength. A mixed-method analysis of variance was used to compare boys and girls at the 2 time points. Pearson correlation coefficients were used to examine relationships between anthropometric and fitness measurements. Significance was set at p ≤ 0.05. Weight increased significantly (>10%) in both sexes, and girls became significantly taller than boys after growing 4.9% by fifth grade (vs. 3.5%). Both groups improved cardiorespiratory endurance and power, although boys performed better than girls at both time points. Boys were stronger in fourth grade, but girls improved more, leading to similar fifth-grade values. Girls were more flexible in fourth grade, but their significant decreases (∼32.4%) coupled with large improvements in boys (∼105%) resulted in similar fifth-grade scores. Body mass index (BMI) was positively correlated with run time regardless of grade or sex. Power was negatively correlated with BMI and run time in fourth grade. In conclusion, sex-specific differences in physical fitness are apparent before pubescence. Furthermore, this selection of measures reveals sexually dimorphic changes, which likely reflect the onset of puberty in girls. Coaches and teachers should account these developmental differences and their effects on anthropometrics and fitness in boys and girls.
Collapse
|