| 1. |
- Ek, Staffan, et al.
(författare)
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Relative Age Effect of Sport Academy Adolescents, a Physiological Evaluation
- 2020
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Ingår i: Sports. - Basel : MDPI. - 2075-4663. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between birth quarter distribution and physiological characteristics related to athletic skills, in adolescent sport academy students has not been fully investigated. In a cross-sectional study, we recruited 86 boys and 52 girls aged 12-14 years during their first term at a sport academy school. We measured body size, cardiac size, pulmonary function, body composition, lower body power, cardiorespiratory fitness parameters, and running endurance by standard methods and analyzed these estimates in relation to birth quarter by ANOVA. Birth quarter distribution in our cohort was compared with birth quarter distribution in the same ages in the whole of Sweden and analyzed by logistic regression. The academy had an overrepresentation of students born in the first quartile of the year compared to those born in the last quartile (odds ratio 2.3 (95% CI: 1.1-4.7)). When comparing the physiological characteristics between birth quarters, uniformity is prominent since out of 26 performed physiological and anthropometric tests only four showed statistically significant group differences. We thus believe that the selection process to the sport academy favours athletes with higher chronological age, i.e., a so-called relative age effect is present. © 2020 MDPI (Basel, Switzerland).
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| 2. |
- Larsson, Jonas, 1968-, et al.
(författare)
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Cardiorespiratory responses of load carriage in female and male soldiers
- 2022
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Ingår i: Applied Ergonomics. - Oxford : Elsevier. - 0003-6870 .- 1872-9126. ; 101
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo investigate the effect of sex and load carriage on cardiorespiratory responses to high intensity exercise in male and female soldiers.MethodsSoldiers (9 women, 9 men) performed a graded treadmill test until exhaustion with no load (NL) and combat-gear with body armor (CG). Cohen's d effect sizes, paired t-tests and ANOVA were used to study differences between conditions. A mixed linear regression model analyzed the relationship between heart rate (HR) and oxygen uptake (V̇O2) with load and between sexes.ResultsWearing CG resulted in, for both sexes, a decreased time to exhaustion (−11 min), lower V̇O2peak (L/min) ES = 0.56; VO2peak (mL//kg/min) ES = 2.44, both p < 0.001, a net decrease in minute ventilation (ES = 3.53) and no change in HRmax. No sex-difference were present except for absolute V̇O2peak. The VO2 and HR relationship showed a cardiorespiratory reduction wearing CG vs. NL. Added load was equal between sexes, although female soldiers' CG relative to body mass was higher (25%) than male soldiers’ (20%), p < 0.01.ConclusionWearing CG reduces soldiers’ cardiorespiratory capacity and exercise performance level, although the reduction cannot be explained solely based on the added load of CG, instead CG seems to restrict the capacity to fully ventilate. No sex differences were found in relative cardiorespiratory responses to wearing CG compared to NL.
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| 3. |
- Larsson, Jonas, 1968-, et al.
(författare)
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Cardiovascular Effects of Load Carriage in Soldiers; A Pilot Study
- 2019
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Ingår i: Book of Abstracts of the 24th Annual Congress of the European College of Sport Science – 3rd - 6th July 2019, Prague – Czech Republic. - : European College of Sport Science. - 9783981841428 ; , s. 422-423
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Konferensbidrag (refereegranskat)abstract
- Introduction: Previous studies have shown that risk of physical fatigue increases if prolonged average work intensity exceeds 50% of oxygen uptake (VO2). In order to avoid persistent fatigue in a work setting, it is important to conduct suitable work capacity analyses. In physically demanding jobs where wearing protective gear and/or external load is mandatory, monitoring of cardiovascular demands through heart rate (HR) is one way to track the workers’ relative effort. There are limited studies examining effects of load carrying on cardiovascular capacity where it appears that VO2peak differ when soldiers and firefighters are tested with work-related equipment/clothing compared to light clothing. The aim of this pilot study was to investigate effects of load (combat gear) on HR, VO2 and muscle oxygen saturation (SmO2) compared to no load in soldiers during a graded treadmill protocol.Methods: Eight volunteer army soldiers (1 woman, 7 men) performed a graded treadmill test until exhaustion. All soldiers performed the test twice, once with light clothes and no load (NL) and once with added load, their personal combat gear (CG), with at least 48 h between sessions. The treadmill protocol stages included supine and standing positions, followed by marching speeds of 5.4 km/h and 8 km/h at 0 incline (all 5 min) immediately followed by a set marching speed of 8 km/h with a starting incline of 2 % increasing the incline 2 % every third minute until voluntary exhaustion. Measurements of HR, VO2 and SmO2 were collected continuously and the last 30 s of each stage were averaged and used for statistical analyses (paired t-tests).Results: The mean added load for all soldiers with CG was 16.8 ± 1.1 kg. All soldiers completed at least 6 stages (range 6-11 stages) with both NL and CG, where time to exhaustion with NL was longer (19.1 ± 3.2 min) compared to CG (9.1 ± 2.9 min; p <0.01). Submaximal HR and VO2 were both significantly higher with CG compared to NL (at absolute intensities) at all marching speeds all soldiers completed (5.4 km/h 0 % grade - 8 km/h 4% grade; all p<0.05). For SmO2, marching with CG compared to NL resulted in increased muscle oxygen utilization, at submaximal stages 8 km/h 0% -4% grade (all p<0.05). For values at maximal effort the CG had a significantly lower VO2peak (3.7 ± 0.5 L/min) compared to NL (4.1 ± 0.6 L/min, p <0.01), whereas there was no difference in HRpeak or the lowest value of SmO2 between CG (193.1 ± 7.2 bpm; 42.4 ± 30.3%) and NL (195.4 ± 8.9 bpm; 47.0 ± 29.2%).Conclusions: This pilot study suggests that assessment of aerobic capacity in soldiers should be conducted with combat gear to help determine their actual work capacity during combat and other load carrying tasks. These results suggest that if soldiers’ work performance is determined without added load it overestimates their aerobic capacity (VO2peak) in tasks wearing combat gear, which might lead to added fatigability and deleterious effect on performance.
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| 6. |
- Larsson, Jonas, 1968-, et al.
(författare)
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Development and application of a questionnaire to self-rate physical work demands for ground combat soldiers
- 2020
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Ingår i: Applied Ergonomics. - Oxford : Elsevier. - 0003-6870 .- 1872-9126. ; 83
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The aim of the present study was to identify the most physically demanding work tasks for Swedish ground combat soldiers through the development and application of a questionnaire survey. This is the first in a series of studies aiming to describe the development process and validation of physical selection standards in the Swedish armed forces.Methods: Based on procedural documentation, combat manuals and job analyses, a questionnaire was developed that defined and rated the perceived physical strain of 30 work tasks for ground combat soldiers. To assess validity, an expert focus group was used and psychometric analysis performed. The questionnaire was then distributed to 231 ground combat soldiers, of whom 165 responded (71%).Results: The questionnaire was validated in three steps to achieve face and content validity, and internal consistency was acceptable (Chronbach's alpha ≥0.95). Of the 30 work tasks included in the survey, transport of wounded was rated as the most demanding task for both aerobic capacity and strength. Other highly demanding tasks for aerobic capacity included combat movement (low/high crawl), dismounted attack in close country, urban and rough terrain and carrying heavy loads. There were no gender differences for either aerobic or strength demands in the top five most challenging tasks based on proportions.Conclusions: This study identified the most physically demanding tasks performed in the Swedish ground combat forces. Almost all the physically demanding tasks found in the present study contain elements of lifting and carrying, which require muscular strength and muscular endurance, with no gender differences. © 2019 Elsevier Ltd. All rights reserved.
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| 7. |
- Larsson, Jonas, 1968-, et al.
(författare)
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Physiological Demands and Characteristics of Movement During Simulated Combat
- 2023
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Ingår i: Military medicine. - New York, NY : Oxford University Press. - 0026-4075 .- 1930-613X. ; 188:11-12, s. 3496-3505
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Military tasks place considerable physiological demands on the soldier. It is therefore important to know the energy expenditure of soldiers while solving tasks in different environments. The purpose of this study was to describe the cardiorespiratory demands of certain movements and activities on ground combat soldiers during military field operations using body sensors and simulated combat.MATERIALS AND METHODS: Movement characteristics and cardiorespiratory responses were assessed in 42 soldiers (three women) in the Swedish Army. The different posts assessed were commander, combat engineer, driver, and gunner. The military field exercises examined were urban operations and retrograde operations in rough terrain. Measurements included (1) body mass, (2) heart rate (HR) including maximal (HRmax), (3) velocity, (4) accelerations/decelerations, and (5) distance moved. Maximal aerobic capacity (V̇O2peak, mL·kg-1·min-1) was tested in a laboratory setting when wearing combat gear and body armor.RESULTS: There was a weak positive correlation (r = 0.41 and 0.28, both P < .05) between VO2peak and percentage of time over 40% and 50% of maximal aerobic capacity during simulated combat. No differences were found for the different posts in time spent over 40% or 50% of maximal aerobic capacity and 76% of their HRmax (P > .05). Wearing combat gear and additional load while solving tasks resulted in mean HR varying between 98 and 111 beats·min-1, corresponding with 50-57% of the soldiers HRmax. Studying all exercises, mean HR was 105 ± 11 beats min-1, 54 ± 5% of HRmax corresponding to light work intensity. Soldiers performed between 2.8 and 4.9 accelerations/min in the different exercises. A significant correlation between V̇O2peak (mL kg-1 min-1) and acceleration and m/min were found, implying that soldiers with good aerobic capacity were able to cope better with tasks requiring quick movements.CONCLUSION: Conducting military operations in urban terrain and retrograde operations in rough terrain strains ground combat soldiers' cardiorespiratory system, with work intensities close to 40% of maximal aerobic capacity in 15-33% of mission time. Tasks with external load carriage include change of direction, accelerations, bounds, and jumping over obstacles, and physical fitness tests should replicate this. Findings in this study also add objective data to the physiological demands of work performed by combat soldiers while conducting urban operations and retrograde operations in rough terrain. These findings could be used to develop a model for classifying work demands for ground combat forces. © The Association of Military Surgeons of the United States 2022.
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| 8. |
- Larsson, Jonas, 1968-, et al.
(författare)
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Self-rated physical work demands for ground combat soldiers
- 2018
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Ingår i: PES 2018 3rd International Conference on Physical Employment Standards, University of Portsmouth, United Kingdom, 17-19 July 2018. ; , s. 31-31
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Konferensbidrag (refereegranskat)abstract
- Introduction: Military tasks are physically demanding, and the ability to achieve and maintain the physical capacity required to perform all military tasks are important. Previous studies in other countries have identified the most physically demanding work tasks to be carrying, lifting heavy loads, and digging. The aim of the present study was to identify the most physically demanding work tasks for Swedish ground combat soldiers and to study gender differences in perceived difficulty of the tasks.Methods: Based on procedural documentation, field manuals and job analyses, a questionnaire was developed that defined 30 work tasks for ground combat soldiers. To assess face and content validity, an expert focus group was used. The questionnaire was distributed to 231 ground combat soldiers, 165 of whom responded (71.4%), rating the perceived physical strain of the identified work tasks.Results: Of the 30 item work tasks included in the survey, five were selected as the most physically demanding. Transport of wounded was rated as the most demanding task both for aerobic endurance and strength. Other highly demanding tasks for aerobic capacity were low/high crawl, dismounted attack in close country, urban and rough terrain, and carrying heavy loads. For muscle strength demands there were a total of 11 different work task ranked for hand-, arm-, leg-, and core strength although many of them only occurred in one of the areas of interest. Carrying heavy loads were ranked in second place except for leg and core strength there it was in third place, instead high and low crawl was ranked very strenuous for leg and core strength. Care of wounded were ranked high for hand strength but not so hard for the rest of the areas.Conclusions: Swedish ground combat soldiers rate many tasks as physically demanding. Almost all the identified tasks were physically challenging and contains elements of lifting and carrying, which demand personnel’s muscular strength and muscular endurance capabilities for the soldiers. There were no significant differences in ranked physical requirements between male and female soldiers although they sometimes ranked the tasks in different order.
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