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Wills JA, Saxby DJ, Glassbrook DJ, Doyle TLA. Sex-Specific Physical Performance Adaptive Responses Are Elicited After 10 Weeks of Load Carriage Conditioning. Mil Med 2023; 188:658-664. [PMID: 34791364 DOI: 10.1093/milmed/usab470] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/06/2021] [Accepted: 10/27/2021] [Indexed: 11/12/2022] Open
Abstract
INTRODUCTION The purpose of this study was to identify and characterize sex-specific physical and psychophysical performance adaptations in response to a novel 10-week training program. MATERIALS AND METHODS Fifteen males and thirteen females completed a standardized load carriage task (5 km at 5.5 km.h-1, wearing a 23 kg torso-borne vest) before and after 10 weeks of resistance and load carriage training. Psychophysical responses (i.e., heart rate and ratings of perceived exertion) were measured throughout the load carriage task. Physical performance (i.e., countermovement and squat jumps, push-ups, sit-ups, and beep test) was measured at before, mid-way, and after the training program (weeks 0, 6, and 11, respectively). RESULTS Training elicited significant improvements in squat jump maximal force, push-ups, and beep test performance (P < .05). Males outperformed females in all performance measures, with interactions (time, sex) for push-ups, sit-ups, and beep test performance. After training, aerobic capacity improved by 5.4% (42.9 mL· kg-1· min-1 to 45.2 mL· kg-1· min-1) in males but did not improve in females. Psychophysical responses decreased for both sexes (P < .05) during the load carriage task post-training. CONCLUSION While 10 weeks of standardized training elicited positive adaptations in both physical and psychophysical performance, sex-specific differences were still evident. To lessen these differences, sex-specific training should be considered to optimize load carriage performance.
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Affiliation(s)
- Jodie A Wills
- Department of Health Professions, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - David J Saxby
- School of Allied Health Sciences & Gold Coast Orthopaedic Research & Education Alliance (GCORE), Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD 4222, Australia
| | - Daniel J Glassbrook
- Department of Health Professions, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Timothy L A Doyle
- Department of Health Professions, Macquarie University, Macquarie Park, NSW 2109, Australia
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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.
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Affiliation(s)
- Kellen T Krajewski
- Neuromuscular Research Laboratory and Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Dennis E Dever
- Neuromuscular Research Laboratory and Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Camille C Johnson
- Biodynamics Laboratory, Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States
| | - Qi Mi
- Neuromuscular Research Laboratory and Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Richard J Simpson
- Department of Nutritional Sciences, University of Arizona, Tucson, AZ, United States
| | - Scott M Graham
- School of Applied Sciences, Edinburgh Napier University, Edinburgh, United Kingdom
| | - Gavin L Moir
- Exercise Science Department, East Stroudsburg University, East Stroudsburg, PA, United States
| | - Nizam U Ahamed
- Neuromuscular Research Laboratory and Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - Shawn D Flanagan
- Neuromuscular Research Laboratory and Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
| | - William J Anderst
- Biodynamics Laboratory, Department of Orthopedic Surgery, University of Pittsburgh, Pittsburgh, PA, United States
| | - Chris Connaboy
- Neuromuscular Research Laboratory and Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, United States
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Earl-Boehm JE, Poel DN, Zalewski K, Ebersole KT. The effects of military style ruck marching on lower extremity loading and muscular, physiological and perceived exertion in ROTC cadets. ERGONOMICS 2020; 63:629-638. [PMID: 32191155 DOI: 10.1080/00140139.2020.1745900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 03/02/2020] [Indexed: 06/10/2023]
Abstract
Military ruck marching with load carriage increases ground reaction forces, which are related to bone stress injuries (BSI). This study's purpose was to examine whether a ruck march increases impact loading and to describe muscular, physiological and perceived exertion in Army Reserve Officer Training Corps (ROTC) cadets. Secondary purposes examined relationships among loading changes after the ruck march and baseline characteristics. Fifteen Army ROTC cadets performed a 4-mile march. Lower extremity loading and muscular, physiological and perceived exertion were measured pre- and post-march. Results indicated significant increases in peak impact force and loading rate and decreases in ankle dorsiflexion and plantarflexion strength. Factors that might have been related to changes seen in lower extremity loading did not yield any compelling relationships to explain those changes. In conclusion, the ruck march led to increased peak impact force and loading rate, which have been shown to be related to the risk of BSI. Practitioner summary: This study examined ROTC cadets ankle strength and lower extremity loading before and after a ruck march. We found that lower extremity loading increased after the march, and ankle dorsiflexion (DF) strength decreased, despite the cadets not feeling fatigued. These changes are consistent with risk factors for bone stress injuries. Abbreviations: BSI: bone stress injury; ROTC: Reserve Officer Training Corps; PIF: peak impact force; LR: loading rate; RPE: rate of perceived exertion; APFT: Army physical fitness test; DF: dorsiflexors; PF: plantar-flexors; INV: invertors; EV: evertors; HHD: handheld dynamometer; %HRmax: percentage of maximum heart rate.
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Affiliation(s)
- Jennifer E Earl-Boehm
- Department of Kinesiology - Integrated Healthcare and Performance, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Daniel N Poel
- Sanford Sports Science Institute - Sanford Health, Sioux Falls, SD, USA
| | - Kathryn Zalewski
- School of Health Care Professions, University of Wisconsin-Stevens Point, Stevens Point, WI, USA
| | - Kyle T Ebersole
- Department of Kinesiology - Integrated Healthcare and Performance, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
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Looney DP, Santee WR, Blanchard LA, Karis AJ, Carter AJ, Potter AW. Cardiorespiratory responses to heavy military load carriage over complex terrain. APPLIED ERGONOMICS 2018; 73:194-198. [PMID: 30098635 DOI: 10.1016/j.apergo.2018.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 06/06/2018] [Accepted: 07/17/2018] [Indexed: 06/08/2023]
Abstract
This study examined complex terrain march performance and cardiorespiratory responses when carrying different Soldier loads. Nine active duty military personnel (age, 21 ± 3 yr; height, 1.72 ± 0.07 m; body mass (BM), 83.4 ± 12.9 kg) attended two test visits during which they completed consecutive laps around a 2.5-km mixed terrain course with either a fighting load (30% BM) or an approach load (45% BM). Respiratory rate and heart rate data were collected using physiological status monitors. Training impulse (TRIMP) scores were calculated using Banister's formula to provide an integrated measure of both time and cardiorespiratory demands. Completion times were not significantly different between the fighting and approach loads for either Lap 1 (p = 0.38) or Lap 2 (p = 0.09). Respiration rate was not significantly higher with the approach load than the fighting load during Lap 1 (p = 0.17) but was significantly higher for Lap 2 (p = 0.04). However, heart rate was significantly higher with the approach load versus the fighting load during both Lap 1 (p = 0.03) and Lap 2 (p = 0.04). Furthermore, TRIMP was significantly greater with the approach load versus the fighting load during both Lap 1 (p = 0.02) and Lap 2 (p = 0.02). Trained military personnel can maintain similar pacing while carrying either fighting or approach loads during short mixed terrain marches. However, cardiorespiratory demands are greatly elevated with the approach load and will likely continue to rise during longer distance marches.
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Affiliation(s)
- David P Looney
- US Army Research Institute of Environmental Medicine (USARIEM), 10 General Green Ave, Natick, MA, 01760, USA.
| | - William R Santee
- US Army Research Institute of Environmental Medicine (USARIEM), 10 General Green Ave, Natick, MA, 01760, USA; Oak Ridge Institute for Science and Education (ORISE), 1299 Bethel Valley Rd, Oak Ridge, TN, 37830, USA
| | - Laurie A Blanchard
- US Army Research Institute of Environmental Medicine (USARIEM), 10 General Green Ave, Natick, MA, 01760, USA
| | - Anthony J Karis
- US Army Research Institute of Environmental Medicine (USARIEM), 10 General Green Ave, Natick, MA, 01760, USA
| | - Alyssa J Carter
- US Army Research Institute of Environmental Medicine (USARIEM), 10 General Green Ave, Natick, MA, 01760, USA
| | - Adam W Potter
- US Army Research Institute of Environmental Medicine (USARIEM), 10 General Green Ave, Natick, MA, 01760, USA
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Colosio AL, Pogliaghi S. Quantification of energy expenditure of military loaded runs: what is the performance of laboratory-based equations when applied to the field environment? J ROY ARMY MED CORPS 2018; 164:253-258. [DOI: 10.1136/jramc-2017-000887] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 11/04/2022]
Abstract
IntroductionPerformance during army loaded runs provides a synthetic indicator of a soldier’s capacity to move while carrying loads and thereby remain able to execute a mission. The aim of this study was to estimate and compare the energy expenditure (EE) of army loaded runs, conducted in a field environment using laboratory-based equations and HR index (HRindex).Methods45 Ranger recruits had HR monitored during three loaded runs (10, 15 and 20 km) in full military equipment in the field environment. EE was calculated using reference equations (EE-Eq) and estimates of oxygen consumption based on HRindex (EE-HRindex). Correspondence between EE-Eq and EE-HRindex estimates was evaluated using a two-way analysis of variance, correlation test and Bland-Altman analysis.ResultsEE-Eq relative to time and weight was significantly higher for the 10 km (0.175±0.016) compared with 15 and 20 km (0.163±0.016 and 0.160±0.013 kcal/kg/min, not different). The overall EE-Eq increased significantly with distance (1129±59, 1703±80 and 2250±115 kcal for 10, 15 and 20 km). EE-Eq was not different from and highly correlated with EE-HRindex, with a small and non-significant bias and good precision between methods.ConclusionsOur study provides the first comprehensive data on HR and EE during long-distance loaded army runs, in full combat equipment, in actual field conditions. Equation-based estimates of EE during these heavy-intensity activities were not significantly different from and highly correlated with HR-based estimates. This corroborates the general applicability of the predictive equations in the field environment. Furthermore, our study suggests that time-resolved HR-based estimates of EE during army runs can be used to evaluate for the effects of context specificity, individual variability and fatigue in movement economy.
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Maximal tachycardia and high cardiac strain during night shifts of emergency physicians. Int Arch Occup Environ Health 2017; 90:467-480. [PMID: 28271382 DOI: 10.1007/s00420-017-1211-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 02/17/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE To compare tachycardia and cardiac strain between 24-hour shifts (24hS) and 14-hour night shifts (14hS) in emergency physicians (EPs), and to investigate key factors influencing tachycardia and cardiac strain. METHODS We monitored heart rate (HR) with Holter-ECG in a shift-randomized trial comparing a 24hS, a 14hS, and a control day, within a potential for 19 EPs. We also measured 24-h HR the third day (D3) after both shifts. We measured perceived stress by visual analog scale and the number of life-and-death emergencies. RESULTS The 17 EPs completing the whole protocol reached maximal HR (180.9 ± 6.9 bpm) during both shifts. Minutes of tachycardia >100 bpm were higher in 24hS (208.3 ± 63.8) than in any other days (14hS: 142.3 ± 36.9; D3/14hS: 64.8 ± 31.4; D3/24hS: 57.6 ± 19.1; control day: 39.2 ± 11.6 min, p < .05). Shifts induced a cardiac strain twice higher than in days not involving patients contact. Each life-and-death emergency enhanced 26 min of tachycardia ≥100 bpm (p < .001), 7 min ≥ 110 bpm (p < .001), 2 min ≥ 120 bpm (p < .001) and 19 min of cardiac strain ≥30% (p = .014). Stress was associated with greater duration of tachycardia ≥100, 110 and 120 bpm, and of cardiac strain ≥30% (p < .001). CONCLUSION We demonstrated several incidences of maximal HR during shifts combined with a high cardiac strain. Duration of tachycardia were the highest in 24hS and lasted several hours. Such values are comparable to those of workers exposed to high physical demanding tasks or heat. Therefore, we suggest that EPs limit their exposure to 24hS. We, furthermore, demonstrated benefits of HR monitoring for identifying stressful events. ClinicalTrials.gov identifier: NCT01874704.
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Simpson RJ, Graham SM, Connaboy C, Clement R, Pollonini L, Florida-James GD. Blood lactate thresholds and walking/running economy are determinants of backpack-running performance in trained soldiers. APPLIED ERGONOMICS 2017; 58:566-572. [PMID: 27154276 DOI: 10.1016/j.apergo.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 04/18/2016] [Accepted: 04/19/2016] [Indexed: 06/05/2023]
Abstract
We developed a standardized laboratory treadmill protocol for assessing physiological responses to a simulated backpack load-carriage task in trained soldiers, and assessed the efficacy of blood lactate thresholds (LTs) and economy in predicting future backpack running success over an 8-mile course in field conditions. LTs and corresponding physiological responses were determined in 17 elite British soldiers who completed an incremental treadmill walk/run protocol to exhaustion carrying 20 kg backpack load. Treadmill velocity at the breakpoint (r = -0.85) and Δ 1 mmol l(-1) (r = -0.80) LTs, and relative V˙O2 at 4 mmol l(-1) (r = 0.76) and treadmill walk/run velocities of 6.4 (r = 0.76), 7.4 (r = 0.80), 11.4 (r = 0.66) and 12.4 (r = 0.65) km h(-1) were significantly associated with field test completion time. We report for the first time that LTs and backpack walk/run economy are major determinants of backpack load-carriage performance in trained soldiers.
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Affiliation(s)
- Richard J Simpson
- Laboratory of Integrated Physiology, Department of Health and Human Performance, University of Houston, 3875 Holman Street, Houston, TX 77204, USA; Biomedicine and Sports Science Research Group, School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, Scotland, UK.
| | - Scott M Graham
- Biomedicine and Sports Science Research Group, School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, Scotland, UK
| | - Christopher Connaboy
- Neuromuscular Research Laboratory, Warrior Human Performance Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Richard Clement
- Biomedicine and Sports Science Research Group, School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, Scotland, UK
| | - Luca Pollonini
- Department of Engineering Technology, University of Houston, 4734 Calhoun Road, Houston, TX 77004, USA
| | - Geraint D Florida-James
- Biomedicine and Sports Science Research Group, School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh EH11 4BN, Scotland, UK
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Zhang YS, Zhang HR. Effect of Helicobacter pylori infection on gastroesophageal reflux disease. Shijie Huaren Xiaohua Zazhi 2014; 22:4107-4112. [DOI: 10.11569/wcjd.v22.i27.4107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gastroesophageal reflux disease (GERD) is a common chronic disease of the digestive system. In recent years, due to the better understanding of Helicobacter pylori (H. pylori) and the wide clinical application of proton pump inhibitors, the rate of H. pylori infection is declining, while the incidence of GERD is increasing. This phenomenon suggests a possible relationship between H. pylori infection and the incidence of GERD. The pathogenesis of GERD is related to the dysfunction of the protective esophageal barrier, esophageal motility, gastric acidity and gastric emptying, and H. pylori infection may affect these factors to exert an impact on the incidence of GERD.
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Rodrigues L, Faria CMD, Geocze S, Chehter L. Helicobacter pylori eradication does not influence gastroesophageal reflux disease: a prospective, parallel, randomized, open-label, controlled trial. ARQUIVOS DE GASTROENTEROLOGIA 2012; 49:56-63. [PMID: 22481687 DOI: 10.1590/s0004-28032012000100010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 09/01/2011] [Indexed: 11/21/2022]
Abstract
CONTEXT Helicobacter pylori has been associated with worsening of gastroesophageal reflux disease (GERD). OBJECTIVE To evaluate the effect of H. pylori eradication in GERD patients. METHODS We conducted a prospective, randomized, controlled trial performing symptom evaluation, endoscopy, histology, manometry and esophageal pH testing on GERD patients. Patients infected with H. pylori were randomized to: 1) eradication treatment plus proton pump inhibitors treatment, or 2) proton pump inhibitors alone. Patients not infected constituted a negative control group. After 3 months, patients were re-evaluated by symptom assessment, endoscopy, histology and manometry. RESULTS GERD treatment resulted in significantly higher lower esophageal sphincter pressure, as measured by mean expiratory pressure, in H. pylori negative patients. There was significantly lower proportion of hypotensive waves and significantly higher proportion of normotensive waves in non-eradicated patients. All symptom scores were significantly reduced in the post-treatment period compared to baseline, to values that were similar among the three groups, in the post-treatment period. In the post-treatment period, erosive esophagitis was significantly less frequent on those not eradicated. CONCLUSION Manometric, clinical and endoscopic data showed no benefit in eradicating H. pylori in GERD. Our data supports the hypothesis that H. pylori eradication does not influence GERD.
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