In military service, marching is an important, common, and physically demanding task. Minimizing dropouts, maintaining operational readiness during the march, and achieving a fast recovery are desirable because the soldiers have to be ready for duty, sometimes shortly after an exhausting task. The present field study investigated the influence of the soldiers' cardiorespiratory fitness on physiological responses during a long-lasting and challenging 34 km march.; Heart rate (HR), body core temperature (BCT), total energy expenditure (TEE), energy intake, motivation, and pain sensation were investigated in 44 soldiers (20.3 ± 1.3 years, 178.5 ± 7.0 cm, 74.8 ± 9.8 kg, body mass index: 23.4 ± 2.7 kg × m-2, peak oxygen uptake (VO2peak): 54.2 ± 7.9 mL × kg-1 × min-1) during almost 8 hours of marching. All soldiers were equipped with a portable electrocardiogram to record HR and an accelerometer on the hip, all swallowed a telemetry pill to record BCT, and all filled out a pre- and post-march questionnaire. The influence of aerobic capacity on the physiological responses during the march was examined by dividing the soldiers into three fitness groups according to their $\dot{\rm{V}}$O2peak.; The group with the lowest aerobic capacity (VO2peak: 44.9 ± 4.8 mL × kg-1 × min-1) compared to the group with the highest aerobic capacity (VO2peak: 61.7 ± 2.2 mL × kg-1 × min-1) showed a significantly higher (p
Hintergrund: Der Stand der Forschung zeigt auf, dass Kreuzbandverletzungen im alpinen Skirennsport häufig vorkommen. Der ischiocruralen Muskulatur wird eine wichtige Rolle zum Schutz des vorderen Kreuzbandes (VKB) attestiert. Dabei ist v.a. die exzentrische Muskelaktivität von grosser Bedeutung, da sie in Dauer und Intensität gegenüber der konzentrischen Muskelaktivität im alpinen Skirennsport vorherrschend ist. Ziel dieser Studie war herauszufinden, ob Elite Skirennfahrer nach einer VKB-Plastik exzentrische Kraftdefizite der ischiocruralen Muskulatur aufweisen. Methode: Es wurde eine Case-Control-Studie zwischen Skirennfahrer 49 ± 41 Monaten postoperativ nach einer VKB-Plastik und gesunden Skirennfahrer durchgeführt. Im Seitenvergleich wurde die exzentrische Gesamtkraft beider Beine der ischiocruralen Muskulatur der VKB- (n=18) mit der Kontrollgruppe (n=70), ferner die Kraft des operierten Beines einerseits mit der gesunden Seite und andererseits mit dem Mittelwert der gesunden Gruppe verglichen. Die exzentrische Kraft wurde während der Übung Nordic-Hamstrings auf dem NordBord gemessen. Gruppenvergleiche wurden mittels ANOVA mit Bonferroni Post-hoc Tests analysiert. Mittels multipler linearer Regressionsanalyse wurden zudem die relevanten unabhängigen Einflussvariablen zur Erklärung der exzentrischen Gesamtkraft und des Limb Symmetry Index ermittelt. Ergebnisse: Die relative exzentrische Gesamtkraft beider Beine der ischiocruralen Muskulatur der VKB-Gruppe war signifikant geringer als diejenige der Kontrollgruppe (p=0.031). Weiter war das operierte Bein bei der relativen exzentrischen Kraft signifikant schwächer als der Mittelwert der Kontrollgruppe (p=0.024). Auch der Limb Symmetry Index war bei den unilateral Operierten signifikant grösser (p=0.016) als bei den Gesunden und den bilateral Operierten. Die Unterschiede in der exzentrischen Gesamtkraft zwischen den Athleten liess sich zu 56% durch die drei unabhängigen Variablen Operation, Alter und Geschlecht erklären. Die Unterschiede im Limb Symmetry Index zwischen den Athleten konnte zu 18% durch die drei unabhängigen Variablen Operation, exzentrische Gesamtkraft beider Beine und Körpergrösse erklärt werden. Schlussfolgerung: Skirennfahrer haben auch mehrere Jahre nach einer VKB-Plastik persistierende Defizite in der exzentrischen Kraft der ischiocruralen Muskulatur verglichen mit gesunden Skirennfahrern. Daher sollte dem Training der exzentrischen Kraftfähigkeit der ischiocruralen Muskulatur während der Rehabilitation aus Sicht der Autoren mehr Aufmerksamkeit gewidmet werden. Die vorgestellte Messmethode ist einfach, praktikabel und kostengünstig. Um den Einfluss der Kraft der ischiocruralen Muskulatur auf Kreuzbandverletzungen besser verstehen zu können, sind weitere Studien nötig.
Introduction Today’s Armed Forces are using data about their soldiers’ physical demands for decision making processes, injury and dropout prevention and training quality management. Increasing amounts of monitors, which can be used for this purpose, are becoming available. To choose the most appropriate device, information about the measurement accuracy, wearing comfort and feasibility is key. It was the aim of an international collaboration study, within the NATO panel HFM 260, to investigate these parameters for different devices used in military organizations worldwide to assess heart rate (HR) and energy expenditure (EE) among soldiers. On the present poster, data on the feasibility part are presented. Method The investigated monitoring devices are shown in Figure 1. Presented data are based on the hard- and software versions available as of January 11th 2017. Human resources were determined by the average time needed for sensor preparation, calibration, fitting on subject, data download and export. Wearing comfort was assessed among 32 volunteers from a Swiss Army infantry training school by questionnaire after wearing each system for one working day, as approved by the local ethics committee (Beeler et al. 2018). For determination of the devices’ measurement time, an epoch time of 30 seconds was set. It was noted if the systems were able to provide real-time data synchronization with a receiver system within a 30 m range, and if they provided raw data. The devices were ranked by their values within each assessed category. The strength and weaknesses of each system are displayed in radar charts (Figure 2). Results The GENEActive device (208 USD and 2 min per subject) needed the fewest monetary and human resources, followed by fēnix 3, Axiamote and Everion (449 to 820 USD and 5-11 min per subject). The most cost and time expensive devices were ActiHeart, EQO2 and Blue Thunder (1054 to 1533 USD and 13 to 22 min per subject). Wearing comfort was rated highest in Axiamote followed by fēnix 3, Everion and ActiHeart. ActiHeart, Aximote and GENEActive provided a measurement duration of 7 days or more. EQO2 and Everion provided a measurement duration of at least 24 hours, while fēnix 3 and Blue Thunder batteries lasted only 20 and 6 hours, respectively. In EQO2, Everion and Blue Thunder real-time tracking with a receiver system on site was available. Only fēnix 3 and ActiHeart did not provide raw data. The greatest overall feasibility score was found in Everion, Axiamote and GENEActive with 16 to 18 ranking points compared to 26 to 30 ranking points in the other devices (Figure 2). Discussion Together with information about measurement accuracy of such monitoring devices, the present study helps decision makers to choose appropriate systems for ambulatory physical activity monitoring in soldiers. However, they have to keep in mind, that hard- and software of the investigated devices might have changed since January 2017 and newer measurement systems are now available on the market. Reference Beeler, N., Roos, L., Delves, SK., Veenstra, BJ., Friedl, K., Buller, MJ., and Wyss, T. (2018). The Wearing Comfort and Acceptability of Ambulatory Physical Activity Monitoring Devices in Soldiers. IISE Transactions on Occupational Ergonomics and Human Factors.
Introduction In many countries, a decrease in cardiorespiratory fitness over the last three decades was observed.1-3 At the same time Wyss, Scheffler, & Mäder 4 demonstrated, that daily military routine often is physically and mentally more demanding than civilian life. Therefore, armed forces have to address the challenge of this imbalance between physical capabilities and physical demands of their trainees and soldiers. Thus, armed forces rely amongst other on a specific physical selection of their personal and qualitatively and quantitatively good physical training during military service.5-7 Lately, several new projects aiming to enable conscripts and trainees for individual physical preparation prior to military service were developed, resulting in commercially available military-related mobile training applications. Method Firstly, trainees at a Swiss Armed forces training school answered a questionnaire about their individual preparation for basic military training. Secondly, different mobile training applications for conscripts’ preparation for military service were compared. Results A questionnaire answered by 145 trainees of the Swiss Armed Forces showed that they did not perceive themselves as physically ready for military service. Nonetheless, only 18% reported performing specific physical preparation for military service. However, 40% of conscripts perform active customization of their combat boots prior to military service by getting used to wearing and walking in them. The latter shows, that there is some potential to increase the number of conscripts that voluntarily prepare for military service, if an adequate and easy to use instrument would be available. Consequently, the Swiss Armed Forces developed a mobile training application as a digital tool for conscripts to individually prepare for military service. The highlights of the six selected training applications are presented here. The application ready #teamarmee (Swiss Armed Forces) is easy to administer, implements an autonomous fitness test, the training program is based on individual's fitness level and adapted to all military personal functions (or training goals). The FMTK (Swedish Armed Forces) is very well known in Sweden and popular as a contributor to improve the general population’s health. MarsMars (Finnish Defence Forces) is a comprehensive library with training programs for strength, endurance and flexibility, available in twelve languages and allows connectivity to different sport watches. MFT (Danish Defence Forces) is an applicatoin focusing uniquely on military employees and is based on the individual's fitness level and adapted to all military personal functions. 100% Army fit (British Armed Forces) is very popular and displays great graphic design. SummFit (Germany) is based on a training science system with a personalized digital coach and a mix of different training methods. All investigated training applications offer endurance, strength and agility training. Some include flexibility and others balance training as well. Discussion and Conclusion Several high quality mobile training applications, available for the specific preparation for military service, are on the marked. The training programs in these applications factor in individuals’ fitness level and are adapted to the physical demands of specific military functions. Investigations about the effect of such mobile training applications on injury incidence rates and military performance are needed. Further development could be focused on the integration of mental (resilience) training. Lamoureux NR, Fitzgerald JS, Norton KI, Sabato T, Tremblay MS, and Tomkinson GR. Temporal Trends in the Cardiorespiratory Fitness of 2,525,827 Adults Between 1967 and 2016: A Systematic Review. Sports Med. 2019. 49(1): p. 41-55. Wyss T, Beuchat C, Zehr S, and Mäder U. Physical performance in young men at Swiss Army recruitment 1982 to 2005. Schweizerische Zeitschrift für Sportmedizin und Sporttraumatologie. 2009. 57(2): p. 75-77. Wyss T, Roos L, Studer F, Mader U, Beuchat C, and Staub K. Development of physical fitness performance in young Swiss men from 2006 to 2015. Scand J Med Sci Sports. 2019. 29(4): p. 586-596. Wyss T, Scheffler J, and Mader U. Ambulatory physical activity in swiss army recruits. Int J Sports Med. 2012. 33(9): p. 716-22. Roos L, Hofstetter MC, Mader U, and Wyss T. Training Methods and Training Instructors' Qualification Are Related to Recruits' Fitness Development During Basic Military Training. J Strength Cond Res. 2015. 29 Suppl 11: p. S178-S186. Wyss T, Roos L, Hofstetter MC, Frey F, and Mader U. Impact of training patterns on injury incidences in 12 Swiss Army basic military training schools. Mil Med. 2014. 179(1): p. 49-55. Wyss T, Von Vigier RO, Frey F, and Mader U. The Swiss Army physical fitness test battery predicts risk of overuse injuries among recruits. J Sports Med Phys Fitness. 2012. 52(5): p. 513-21.
Purpose: Session rating of perceived exertion (sRPE) is an often-used measure to assess athletes’ training load (TL). However, little is known about which factors could optimize the quality of data collection thereof. The aim of this study was to investigate the effects of the survey methods and the time points when sRPE was assessed on the correlation between subjective (sRPE) and objective (heart-rate training impulse; TRIMP) assessment of TL. Methods: In the first part of the study, 45 well-trained subjects (30 men and 15 women) performed 20 running sessions with a heart-rate monitor and reported sRPE 30 min after training cessation. For the reporting, the subjects were grouped into 3 groups (paper–pencil, online questionnaire, and mobiledevice). In the second part of the study, another 40 athletes (28 men and 12 women) performed 4 × 5 running sessions with the 4 time points to report the sRPE randomly assigned (directly after training cessation, 30 min postexercise, in the evening of the same day, and the next morning directly after waking up). Results: The assessment of sRPE is influenced by time point, survey method, TRIMP, sex, and training type. It is recommended to assess sRPE values via a mobile device or online tool, as the paper survey method displayed lower correlations between sRPE and TRIMP. Conclusions: Subjective TL measures are highly individual. When compared with the same relative intensity, lower sRPE values were reported by women for the training types representing slow runs and for time points with greater duration between training cessation and sRPE assessment. The assessment method for sRPE should be kept constant for each athlete, and comparisons between athletes or sexes are not recommended.
OCCUPATIONAL APPLICATIONS We investigated the wearing comfort of nine devices for monitoring physical activity in a military context. In general, the questionnaire-based survey revealed that the devices were highly acceptable. For long-term monitoring of physical activity in soldiers (>5 days), slightly more participants (85.2%) found that sensors not located at the chest would be more acceptable compared to the chest-worn devices (66.7%). More specifically, our results suggest that devices placed on or around the upper arm, the hip, or the shoe will be preferred over devices worn around the wrist or on or around the chest in a military context. The placement of physical activity monitoring devices around the chest, in particular, can be expected to lead to discomfort due to incompatibilities with military equipment. TECHNICAL ABSTRACT Background: Military organizations use body-worn devices for ambulatory monitoring of physical activity in soldiers. However, little is known regarding the wearing comfort and acceptability of ambulatory monitoring devices as used in the military context. Purpose: To investigate the wearing comfort and acceptability of nine body-worn devices for monitoring physical activity in soldiers. Methods: A total of 27 male volunteers wore three randomly assigned devices simultaneously for one day of basic military training. The participants then completed a questionnaire designed to assess comfort and acceptability. Results: Devices worn on or around the chest were associated with lower wearing comfort and acceptability scores (overall scores of 59.7, 70.8, and 80.9 for Hidalgo EQ02, TICKR X, and ActiHeart, respectively). Devices worn around the wrist, Mio FUSE (80.9), GENEActiv (81.3), and fenix 3 (85.3), had mid-range scores. The highest scores were obtained for the devices Blue Thunder, worn on the shoe (85.5), Axiamote PADIS 2.0, worn on the hip and the backpack (88.9), and Everion, worn on the upper arm (90.1). Conclusions: Body-worn devices for monitoring physical activity are well-accepted in soldiers. The differences between the devices were small for several parameters. Nevertheless, devices that are attached to, or around, the chest, were typically perceived as having a slightly more negative impact on the body. Both wrist- and chest-worn devices received some reports of interfering with military equipment or military tasks.
This study aimed to evaluate the accuracy of three measurement systems estimating gait speed during a loaded military march over graded terrain. Systems developed by the Swiss and Netherlands Armed Forces and a commercial wrist-based device were evaluated in comparison to a Global Positioning System. The first part of the paper focuses on the development of the Dutch system, where speed is estimated from a chest worn accelerometer and body measurements. For this validation study 36 subjects were walking or running 13 laps of 200m at different speeds. Results showed that walking and running speed can be estimated with a R2adj of 0.968 and 0.740, respectively. In the second part of this paper, data from 64 soldiers performing a 35 km march were used to evaluate the accuracy of three measurement systems in estimating speed. Data showed that estimating gait speed with a single accelerometer can be accurate for military activity, even without prior individual calibration measurements. However, predictions should be corrected for confounders such as body size and shoe type to be accurate. Both, downhill and uphill walking led to changes in gait characteristics and to an overestimation of speed by up to 10%. Correcting for slope or gradient using altimetry in future algorithms/experiments could improve the estimation of gait speed.
The purpose of this study was to evaluate the wrist-worn device Mio FUSE, which estimates heart rate (HR) based on photo-plethysmography, 1) in a large study group during a standardised activity, 2) in a small group during a variety of activities and 3) to investigate factors affecting HR accuracy in a real-world setting. First, 53 male participants (20 ±1 years; 1.79 ±0.07 m; 76.1 ±10.5 kg) completed a 35-km march wearing the Equivital EQ-02 as a criterion measure. Second, 5 participants (whereof 3 female; 29 ±5 years; 1.74 ±0.07 m; 67.8 ±11.1 kg) independently performed 25 activities, categorised as sitting passive, sitting active, standing, cyclic and anti-cyclic activities with the Polar H7 as a criterion device. Equivalence testing and Bland-and-Altman analyses were undertaken to assess the accuracy to the criterion devices. Third, confounders affecting HR accuracy were investigated using multiple backwards regression analyses. The Mio FUSE was equivalent to the respective criterion measures with only small systematic biases of -3.5 bpm (-2.6%) and -1.7 bpm (-1.3%) with limits of agreements of ±10.1 bpm and ±10.8 bpm during the 35-km march and during different activities, respectively. Confounding factors negatively affecting the accuracy of the Mio FUSE were found to include larger wrist size and intensified arm and/or wrist movement. The wrist-worn Mio FUSE can be recommended to estimate overall HR accurately for different types of activities in healthy adults. However, during sporting activities involving intensified arm and/or wrist movement or for detailed continuous analysis, a chest strap is preferred to the Mio FUSE to optimise HR estimation accuracy.
Abstract This study investigated whether physical fitness affects the perception of chronic stress in military trainees while controlling for established factors influencing stress perception. The sample consisted of 273 men (20.23 ± 1.12 years, 73.56 ± 10.52 kg, 1.78 ± 0.06 m). Physical fitness was measured by progressive endurance run (maximum oxygen uptake; VO2 max), standing long jump, seated shot put, trunk muscle strength, and one leg standing test. Perceived stress was measured using the Perceived Stress Questionnaire in Weeks 1 and 11 of basic military training (BMT). VO2 max and four influencing variables (perceived stress in Week 1, neuroticism, transformational leadership style, and education level) explained 44.44% of the variance of the increase in perceived stress during 10 weeks of BMT (R2 = 0.444, F = 23.334, p < .001). The explained variance of VO2 max was 4.14% (R2 = 0.041), with a Cohen's f2 effect size of 0.045 (assigned as a small effect by Cohen, ). The results indicate a moderating influence of good aerobic fitness on the varied level of perceived stress. We conclude that it is advisable to provide conscripts with a specific endurance training program prior to BMT for stress prevention reasons.
The aim of this study was to develop and cross-validate two models to estimate total energy expenditure (TEE) based on respiration variables in healthy subjects during daily physical activities. Ninety-nine male and female subjects systematically varying in age (18-60 years) and body mass index (BMI; 17-36 kg*m-2) completed eleven aerobic activities with a portable spirometer as the criterion measure. Two models were developed using linear regression analyses with the data from 67 randomly selected subjects (50.0% female, 39.9 ± 11.8 years, 25.1 ± 5.2 kg*m-2). The models were cross-validated with the other 32 subjects (49% female, 40.4 ± 10.7 years, 24.7 ± 4.6 kg*m-2) by applying equivalence testing and Bland-and-Altman analyses. Model 1, estimating TEE based solely on respiratory volume, respiratory rate, and age, was significantly equivalent to the measured TEE with a systematic bias of 0.06 kJ*min-1 (0.22%) and limits of agreement of ±6.83 kJ*min-1. Model 1 was as accurate in estimating TEE as Model 2, which incorporated further information on activity categories, heart rate, sex, and BMI. The results demonstrated that respiration variables and age can be used to accurately determine daily TEE for different types of aerobic activities in healthy adults across a broad range of ages and body sizes.
To quantify gait asymmetry in well-trained runners with and without previous injuries during interval training sessions incorporating different distances.; Twelve well-trained runners participated in 8 high-intensity interval-training sessions on a synthetic track over a 4-wk period. The training consisted of 10 × 400, 8 × 600, 7 × 800, and 6 × 1000-m running. Using an inertial measurement unit, the ground-contact time (GCT) of every step was recorded. To determine gait asymmetry, the GCTs between the left and right foot were compared.; Overall, gait asymmetry was 3.3% ± 1.4%, and over the course of a training session, the gait asymmetry did not change (F1,33 = 1.673, P = .205). The gait asymmetry of the athletes with a previous history of injury was significantly greater than that of the athletes without a previous injury. However, this injury-related enlarged asymmetry was detectable only at short (400 m), but not at longer, distances (600-1000 m).; The gait asymmetry of well-trained athletes differed, depending on their history of injury and the running distance. To detect gait asymmetries, high-intensity runs over relatively short distances are recommended.
Background: The aim of this study was to assess the accuracy of three different sport watches in estimating energy expenditure during aerobic and anaerobic running.Methods: Twenty trained subjects ran at different intensities while wearing three commercial sport watches (Suunto Ambit2, Garmin Forerunner920XT, and Polar V800). Indirect calorimetry was used as the criterion measure for assessing energy expenditure. Different formulas were applied to compute energy expenditure from the gas exchange values for aerobic and anaerobic running.Results: The accuracy of the energy expenditure estimations was intensity-dependent for all tested watches. During aerobic running (4–11 km/h), mean absolute percentage error values of −25.16% to +38.09% were observed, with the Polar V800 performing most accurately (stage 1: −12.20%, stage 2: −3.61%, and stage 3: −4.29%). The Garmin Forerunner920XT significantly underestimated energy expenditure during the slowest stage (stage 1: −25.16%), whereas, the Suunto Ambit2 significantly overestimated energy expenditure during the two slowest stages (stage 1: 38.09%, stage 2: 36.29%). During anaerobic running (14–17 km/h), all three watches significantly underestimated energy expenditure by −21.62% to −49.30%. Therefore, the error in estimating energy expenditure systematically increased as the anaerobic running speed increased.Conclusions: To estimate energy expenditure during aerobic running, the Polar V800 is recommended. By contrast, the other two watches either significantly overestimated or underestimated energy expenditure during most running intensities. The energy expenditure estimations generated during anaerobic exercises revealed large measurement errors in all tested sport watches. Therefore, the algorithms for estimating energy expenditure during intense activities must be improved before they can be used to monitor energy expenditure during high-intensity physical activities.
