Injuries and risk factors in a 100-mile (161-km) infantry road march

Colophonium-related Allergic Contact Dermatitis Caused by Medical Adhesive Tape Used to Prevent Skin Lesions in Soldiers

Medical adhesive tapes are commonly recommended for the prevention of friction blisters during hiking and military marches. The aim of this paper is to report on the results of investigations into an outbreak of tape-related foot dermatitis in 26 military conscripts following continuous use of medical adhesive tapes for several days during a field exercise. Patch tests were performed using baseline series and aimed testing was performed with colophonium-related substances and different medical adhesive tapes. Contact allergy to the adhesive tapes used was found in 20 (77%) subjects, and contact allergy to colophonium in 16 (61%). Chemical analysis detected colophonium-related substances in the culprit tapes. Compared with consecutive dermatitis patients investigated at our Department of Occupational and Environmental Dermatology in the previous 10 years, conscripts with colophonium allergy had increased odds ratios for concomitant contact allergy to phenol formaldehyde resins and fragrance substances including hydroperoxides of limonene and linalool. The results show that prolonged use of medical adhesive tapes on intact skin carries a high risk for allergic contact dermatitis. Prior to their introduction on the market, medical devices should be assessed for possible side-effects.

Prevention of Lower Extremity Musculoskeletal Injuries in Tactical and First Responder Populations: A Systematic Review and Meta-Analysis of Randomized Trials From 1955 to 2020

ABSTRACT

Sinnott, AM, Krajewski, KT, LaGoy, AD, Beckner, ME, Proessl, F, Canino, MC, Nindl, BC, Turner, RL, Lovalekar, MT, Connaboy, C, and Flanagan, SD. Prevention of lower extremity musculoskeletal injuries in tactical and first responder populations: A systematic review and meta-analysis of randomized trials from 1955 to 2020. J Strength Cond Res 37(1): 239-252, 2023-Lower extremity musculoskeletal injuries (LEMSIs) impose a significant burden on tactical and first responder populations. To determine the effectiveness of LEMSI prevention strategies, we performed a systematic review and meta-analysis of randomized controlled trials published in English from 1955 to 2020 (PROSPERO: CRD42018081799). MEDLINE, EMBASE, Cochrane, CINAHL, ProQuest, and DTIC databases were searched for trials that assigned military service members, police, firefighters, or paramedics to LEMSI prevention interventions with a minimum surveillance period of 12 weeks. Evidence was synthesized as odds ratios (OR) for LEMSI occurrence between individuals assigned to interventions and those assigned to standard activities. Risk of bias was assessed with the Cochrane Risk of Bias tool 2.0. Random-effects meta-analyses were conducted for (a) physical training and (b) footwear modifications to reduce LEMSI and (c) footwear modifications to reduce stress fractures specifically. Certainty in the body of evidence was determined with the GRADE approach. Of 28,499 records, 18 trials comprised of more than 11,000 subjects were synthesized. Interventions included physical training (8, N = 6,838), footwear modifications (8, N = 3,792), nutritional supplementation (1, N = 324), and training modifications (1, N = 350). Overall risk of bias was generally moderate ( N = 7 of 18) or high ( N = 9 of 18). Physical training (OR = 0.87, 95% CI [0.71, 1.08], p = 0.22, I 2 = 58.4%) and footwear modification (OR = 1.13, 95% CI [0.85, 1.49], p = 0.42, I 2 = 0.0%) did not reduce LEMSI or stress fractures (OR = 0.76, 95% CI [0.45, 1.28], p = 0.30, I 2 = 70.7%). Our results indicate that there is weak evidence to support current LEMSI prevention strategies. Future efforts will benefit from longer surveillance periods, assessment of women and nonmilitary populations, improved methodological rigor, and a greater breadth of approaches.

6DOF knee kinematic alterations due to increased load levels

Whether load carriage leads to six-degrees-of-freedom (6DOF) knee kinematic alterations remains unclear. Exploring this mechanism may reveal meaningful knee kinematic information that can be used to improve load carriage conditions, the design of protective devices, and the knowledge of the effects of load carriage on knees. We recruited 44 subjects to explore kinematic alterations from an unloaded state to 60% bodyweight (BW) load carriage. A three-dimensional gait analysis system was used to collect the knee kinematic data. One-way repeated analysis of variance (ANOVA) was used to explore the effects of load levels on knee kinematics. The effects of increasing load levels on knee kinematics were smooth with decreased or increased trends. We found that knees significantly exhibited increased lateral tibial translation (up to 1.2 mm), knee flexion angle (up to 1.4°), internal tibial rotation (up to 1.3°), and tibial proximal translation (up to 1.0 mm) when they went from an unloaded state to 60%BW load carriage during the stance phase (p < 0.05). Significant small knee adduction/abduction angle and posterior tibial translation alterations (<1°/mm) were also identified (p < 0.05). Load carriage can cause significant 6DOF knee kinematic alterations. The results showed that knee kinematic environments are challenging during increased load. Our results contain kinematic information that could be helpful for knee-protection-related activities, such as target muscle training to reduce abnormal knee kinematics and knee brace design.

Perception of the Special Troops (Commando) Soldiers Regarding Physical Fitness, Motor Control and Psychological Skills

Physical fitness and motor skills are considered important attributes for the military, affecting their professional performance. The high physical and psychological demand that the special forces are subjected to requires the acquisition of a set of volitional skills such as resilience, effort, perseverance, or resistance to frustration, which are worthy of further research. This study aimed to analyse the perception of the special troops (commandos) in physical fitness, motor control and psychological skills. A total of 35 male soldiers that ended the commando recruit training program (21.69 ± 2.36 years old) were investigated. A questionnaire was applied to verify differences in perception of physical fitness, motor capacity, physical effort and military training during recruit training according to age, education, work experience and sports background. Descriptive statistics were used to characterize the participants. All data collected were analysed using IBM-SPSS Statistics, version 24. Our results revealed differences in the importance given to the training of motor skills within military training (χ2 = 19.284; p = 0.023), conditional motor skills – speed (χ2 = 17.378; p = 0.043), coordinative motor skills—motor control (χ2 = 20.616; p = 0.014), psychological skills in a military context (χ2 = 13.730; p = 0.008), volitional skills—resistance to frustration (χ2 = 21.568; p = 0.043) and volitional skills—psychological resistance (χ2 = 29.144; p = 0.004). The participants highlighted the importance of instructors having scientific knowledge in physical education to provide military physical training to be better prepared for this purpose. We concluded that motor skills and psychological abilities tend to be equally important in the context of military training. Physical fitness and motor skill development can be considered essential in military training for most of the inquired participants.

Profiling the Injuries Sustained by Police Trainees Undergoing Initial Training: A Retrospective Cohort Study

The tasks performed by police officers are unique, varied and can be performed in unexpected situations. Initial police college training is used to prepare new police officers to conduct these tasks and is known to be a time when police trainees are at an elevated risk of injury. The aim of this study was to profile injuries occurring within a national Police Force during initial training to inform injury prevention strategies. Using a retrospective cohort design, point-of-care injury data including injury body site, nature, mechanism, and the activity being performed at the time of injury were provided. A total of 564 injuries were recorded over the 22-month period, with the mean age of recruits reporting an injury being 28.83 years ± 6.9 years. The incidence of injuries ranged across training periods, from 456.25 to 3079 injuries per 1000 person-years with an overall incidence rate of 1550.15 injuries per 1000 person-years. The shoulder was the most injured site (n = 113, 20% of injuries), with sprains and strains being the most common nature of injury (n = 287, 50.9% of injuries). Muscular stress with physical exercise was the most common mechanism of injury (n = 175, 31.0% of injuries) with the activity responsible for the largest proportion of injuries being “unknown” (n = 256, 45.4% of injuries), followed by police training (n = 215, 38.1%). Injuries appear to be typically joint related—commonly the shoulder—with police training being a primary known activity at the time of injury. Prescreening protocols may be of benefit, and efforts should be made to recruit and train physically resilient trainees. Injuries, whether they occurred pre-enlistment or during training, should be fully rehabilitated prior to the individual’s commencement as a qualified officer.

Risk factors for musculoskeletal injuries in military personnel: a systematic review with meta-analysis

OBJECTIVE

To investigate the risk factors for musculoskeletal injuries in military personnel.

METHODS

A systematic literature search was carried out in August 2019 and updated in July 2020 without language or time filters. The inclusion criteria were prospective studies that investigated the risk factors for injuries in military personnel. Only risk factors analyzed by at least ten studies were selected for the meta-analysis. For data analysis, the RevMan5.3 program was used to compare the number of participants with injuries between high- or low-risk groups. The measurement of dichotomous variables was one of the selected parameters for the analysis, as well as the Mantel-Haenszel statistical method, random-effects model, and analysis with a relative risk (RR) and 95% confidence interval for the included studies.

RESULTS

A total of 2,629 studies were identified through databases. Thirty-four studies met the inclusion criteria. The groups considered at risk were the oldest [RR = 1.22; (95% CI 1.06-1.41)], with overweight or obesity [RR = 1.27; (95% CI 1.08-1, 48)], with previous injuries [RR = 1.15; (95% CI 1.01-1.30)], and with the worst performance in running tests of 1,600-3,200 m [RR = 1.87; (95% CI 1.28-2.71)]. Gender, ethnicity, and smoking were not associated with injuries. However, a subgroup analysis showed that among studies with a follow-up of fewer than 12 months, women presented RR = 2.44 (95% CI 1.65-3.60) more likely to develop injuries.

CONCLUSION

Age, overweight or obesity, previous injuries, and performance in the 1600-3200 m run are associated with an increased risk of injury in the military.

Soldier Load Carriage, Injuries, Rehabilitation and Physical Conditioning: An International Approach

Soldiers are often required to carry heavy loads that can exceed 45 kg. The physiological costs and biomechanical responses to these loads, whilst varying with the contexts in which they are carried, have led to soldier injuries. These injuries can range from musculoskeletal injuries (e.g., joint/ligamentous injuries and stress fractures) to neurological injuries (e.g., paresthesias), and impact on both the soldier and the army in which they serve. Following treatment to facilitate initial recovery from injuries, soldiers must be progressively reconditioned for load carriage. Optimal conditioning and reconditioning practices include load carriage sessions with a frequency of one session every 10–14 days in conjunction with a program of both resistance and aerobic training. Speed of march and grade and type of terrain covered are factors that can be adjusted to manipulate load carriage intensity, limiting the need to adjust load weight alone. Factors external to the load carriage program, such as other military duties, can also impart physical loading and must be considered as part of any load carriage conditioning/reconditioning program.

Effects of Short-Term Unilateral Strength Training on Measures of Postural Control When Wearing "Operationally Relevant" Backpack Loads

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.

Medical Encounters During the United States Army Special Forces Assessment and Selection Course

Introduction

The Special Forces Assessment and Selection (SFAS) is an extremely physically and mentally demanding 19- to 20-day course designed to determine whether Soldiers are qualified to enter the Special Forces Qualification Course. As a first step to understand medical problems during SFAS, this study examined injuries, illnesses, and activities associated with injuries during the course.

Materials and Methods

Medical events during the SFAS course were compiled from Sick Call Trackers (a log of medical encounters maintained by medical personnel in the field) and Chronology of Medical Care (Standard Form 600). Descriptive statistics were calculated for each injury and illness and injuries were compiled by the activities performed when the injuries occurred.

Results

Of the 800 Soldiers who volunteered for the study, 38% (n = 307/800) and 12% (n = 97/800) experienced one or more injuries and/or illnesses, respectively. The most common injuries were blisters and abrasions/lacerations with incidences of 20% (n = 158/800) and 13% (104/800), respectively. The most common illnesses were respiratory infections, other infections, contact dermatitis, and allergies with incidences of 7% (n = 57/800), 2% (n = 14/800), 2% (n = 14/800), and 2% (n = 13/800), respectively. Among all injuries recorded (n = 573), the most common were blisters (46%), abrasions/lacerations (24%), pain (not otherwise specified) (19%), tendonitis (3%), and sprains (3%). Among all illnesses recorded (n = 133), the most common were respiratory infections (56%), allergies (11%), contact dermatitis (11%), and other infections (11%). Most injuries were experienced during land navigation (44%), team events (20%), and foot marching (11%), running (6%), and the obstacle course (5%), but when the estimated time involved for each event was considered, activities with the highest injury rates were the obstacle course (65 injuries/hr), running (27 injuries/hr), the Combat Readiness Assessment (activity involving combat-related tasks) (20 injuries/hr), and foot marching (16 injuries/hr).

Conclusion

The major limitations of this investigation were: 1) the low specificity with regard to many of the diagnoses/complaints; and 2) the fact that the medical problems reported here are only those seen by medical care providers and are likely an underestimate of the total morbidity in the SFAS course. Soldiers often self-treat and some may be reluctant to see medical personnel because of how it might affect their rating in the course. Nonetheless, this investigation alerts medical personnel to the injuries and illnesses to expect, and public health workers and leadership with activities to target for injury prevention measures during SFAS.

What is the impact of fitness on injury risk during police academy training? A retrospective cohort study

BACKGROUND

In the conduct of their daily duties, law enforcement officers (LEO) are often required to perform dynamic, physically demanding tasks with little or no notice, sometimes at maximal levels of exertion. Given these requirements, training for prospective LEOs must be rigorous enough to ensure that when trainees graduate, they are competent in their response to crisis and resilient enough to maintain this for the span of their career. Therefore, based on previously reported effectiveness of fitness testing in predicting injury risk in predominantly military settings, the aim of this study was to investigate relationships between a physical ability test (PAT) and risk of injury during police recruit training.

METHODS

Retrospective PAT results and trainee injury records were obtained from a national police department and Mann-Whitney U tests were performed to investigate fitness differences between trainees who were, or were not, injured. Significant results were tested for effect size using Cliff's delta (CD).

RESULTS

Significant differences in mean performance between groups existed for the following PAT components: pushups (injured mean 32.94 ± 8.66 reps, uninjured mean 35.67 ± 9.04 reps, p = 0.01 CD + 0.11) and right-hand grip strength (injured mean 49.61 ± 12.51 kg, uninjured mean 52.12 ± 11.17 kg, p = 0.042 CD + 0.22) for all injuries; vertical jump height (injured mean 51.75 ± 7.54 cm, uninjured mean 55.06 ± 8.19 cm, p = 0.032 CD + 0.41) for lower limb injuries, and all measures of grip strength for trunk injury.

CONCLUSIONS

The results of this study suggest that a significant relationship between some PAT fitness components and injury risk exists during police recruit training.

Parâmetros da pressão plantar, tipo e sensibilidade do pé em recrutas: um estudo prospectivo

RESUMO Este estudo teve como objetivo avaliar as características da pressão plantar, tipo e sensibilidade do pé em recrutas durante o período do serviço militar obrigatório. Sessenta indivíduos que prestaram o serviço militar obrigatório foram avaliados para pressão plantar (baropodômetro EPS LoranEngineering, Bolonha, Itália) e sensibilidade plantar ao toque superficial (estesiômetro de Semmes-Weinsten) em três momentos distintos: março (linha de base), junho (após 16 semanas de treinamento) e setembro (após 36 semanas de treinamento militar). Foram avaliadas a descarga de peso ântero-posterior e latero-lateral, pressão média, pressão máxima, área de contato do pé, tipologia de pé e sensibilidade plantar. Os dados foram analisados pelo teste do Qui-quadrado, anova de medidas repetidas e pelo teste de Friedman com pos hoc de Bonferroni (p<0,05). Houve aumento na área de contato (p=0,001) e na pressão média de ambos os pés (p<0,001). Quanto a tipologia, aproximadamente 60% dos indivíduos possuíam o pé direito do tipo normal, enquanto o pé esquerdo era do tipo cavo (50,3%); ou seja, mesmos sujeitos apresentaram diferentes tipologias do pé. Em relação a sensibilidade plantar, houve diferença na região do médio pé ao longo do treinamento (p=0,001 no pé dominante e p=0,009 no pé não dominante). Esses resultados demonstram que houve aumento da pressão média e área total de contato do pé, bem como alterações na sensibilidade plantar da região do médio pé ao longo do serviço militar obrigatório.

Foot and ankle kinematics in chronic ankle instability subjects using a midfoot strike pattern when running, including influence of taping

BACKGROUND

Investigate differences in multi-segment foot kinematics between controls and participants with chronic ankle instability during running with a midfoot striking pattern and to evaluate the effect of Low-Dye and High-Dye taping.

METHODS

Three-dimensional multi-segment foot kinematics of 12 controls and 15 participants with chronic ankle instability were collected while running barefoot, and in both taping conditions. Ranges of motion occurring at each joint, each sub phase of stance, were compared between groups and between taping conditions (0-dimensional inference). Kinematic data were also compared using one-dimensional statistical parametric mapping.

FINDINGS

The symptomatic group demonstrated while barefoot running a significantly decreased rearfoot dorsiflexion range of motion during the peak impact phase as well as a less dorsiflexed position from 6 to 12% of the running cycle. During the absorption and generation phase, the symptomatic group also showed a significantly increased rearfoot dorsiflexion and adduction motion as well as an increased midfoot inversion motion. In the peak impact phase of both taping conditions, a decreased midfoot inversion motion was found. The High-Dye taping resulted in a decreased rearfoot plantarflexion motion whereas the Low-Dye caused a decreased midfoot inversion motion.

INTERPRETATION

Persons with chronic ankle instability seem to have altered rearfoot and midfoot kinematics while running with a midfoot striking index. High-Dye taping seems to have better therapeutic features than Low-Dye taping.

Gender differences in load carriage injuries of Australian army soldiers

Background

With the removal of gender restrictions and the changing nature of warfare potentially increasing female soldier exposure to heavy military load carriage, the aim of this research was to determine relative risks and patterns of load carriage related injuries in female compared to male soldiers.

Methods

The Australian Defence Force Occupational Health, Safety and Compensation Analysis and Reporting workplace injury database was searched to identify all reported load carriage injuries. Using key search terms, the narrative description fields were used as the search medium to identify records of interest. Population estimates of the female: male incident rate ratio (IRR) were calculated with ninety-five percent confidence interval (95% CI) around the population estimate of each IRR determined.

Results

Female soldiers sustained 10% (n = 40) of the 401 reported injuries, with a female to male IRR of 1.02 (95% CI 0.74 to 1.41). The most common site of injury for both genders was the back (F: n = 11, 27%; M: n = 80, 22%), followed by the foot in female soldiers (n = 8, 20%) and the ankle (n = 60, 17%) in male soldiers. Fifteen percent (n = 6) of injuries in female soldiers and 6% (n = 23) of injuries in males were classified as Serious Personal Injuries (SPI) with the lower back the leading site for both genders (F: n = 3, 43%: M: n = 8, 29%). The injury risk ratio of SPI for female compared to male soldiers was 2.40 (95% CI 0.98 to 5.88).

Conclusions

While both genders similarly have the lower back as the leading site of injury while carrying load, female soldiers have more injuries to the foot as the second leading site of injury, as opposed to ankle injuries in males. The typically smaller statures of female soldiers may have predisposed them to their observed higher risk of suffering SPI while carrying loads.

Low fitness, low body mass and prior injury predict injury risk during military recruit training: a prospective cohort study in the British Army

Background

Injuries sustained by military recruits during initial training impede training progression and military readiness while increasing financial costs. This study investigated training-related injuries and injury risk factors among British Army infantry recruits.

Methods

Recruits starting infantry training at the British Army Infantry Training Centre between September 2008 and March 2010 were eligible to take part. Information regarding lifestyle behaviours and injury history was collected using the Military Pre-training Questionnaire. Sociodemographic, anthropometric, physical fitness and injury (lower limb and lower back) data were obtained from Army databases. Univariable and multivariable Cox regression models were used to explore the association between time to first training injury and potential risk factors.

Results

58% (95% CI 55% to 60%) of 1810 recruits sustained at least 1 injury during training. Overuse injuries were more common than traumatic injuries (65% and 35%, respectively). The lower leg accounted for 81% of all injuries, and non-specific soft tissue damage was the leading diagnosis (55% of all injuries). Injuries resulted in 122 (118 to 126) training days lost per 1000 person-days. Slower 2.4 km run time, low body mass, past injury and shin pain were independently associated with higher risk of any injury.

Conclusions

There was a high incidence of overuse injuries in British Army recruits undertaking infantry training. Recruits with lower pretraining fitness levels, low body mass and past injuries were at higher risk. Faster 2.4 km run time performance and minimal body mass standards should be considered for physical entry criteria.

Self-reported load carriage injuries of military soldiers

The aim of this study was to investigate whether occupational load carriage constitutes a significant source of injury to military soldiers. An online survey was sent to soldiers serving in specific Australian Army Corps known to experience the greatest occupational exposure to load carriage. Of the 338 respondents, 34% sustained at least one load carriage injury. Fifty-two per cent of those injured during initial training reported sustaining an additional load carriage injury. The majority of injuries (61%) were to the lower limbs with bones and joints the most frequently injured body structures (39%). Endurance marching (continuous marching as part of a physical training session) was the activity accounting for most (38%) injuries. Occupational load carriage is associated with military soldier injuries and, once injured, soldiers are at a high risk of future load carriage injury. The bodily sites and nature of self-reported injuries in this study are akin to those of formally reported injuries and those of other militaries.

Predicting physiological capacity of human load carriage - a review

This review article aims to evaluate a proposed maximum acceptable work duration model for load carriage tasks. It is contended that this concept has particular relevance to physically demanding occupations such as military and firefighting. Personnel in these occupations are often required to perform very physically demanding tasks, over varying time periods, often involving load carriage. Previous research has investigated concepts related to physiological workload limits in occupational settings (e.g. industrial). Evidence suggests however, that existing (unloaded) workload guidelines are not appropriate for load carriage tasks. The utility of this model warrants further work to enable prediction of load carriage durations across a range of functional workloads for physically demanding occupations. If the maximum duration for which personnel can physiologically sustain a load carriage task could be accurately predicted, commanders and supervisors could better plan for and manage tasks to ensure operational imperatives were met whilst minimising health risks for their workers.

Reported load carriage injuries of the Australian army soldier

INTRODUCTION

Many injuries experienced by soldiers can be attributed to the occupational loads they are required to carry.

PURPOSE

The aim of this study was to determine whether contemporary military load carriage is a source of injuries to Australian Regular Army soldiers and to profile these injuries.

METHODS

The Australian Defence Force 'Occupational Health, Safety and Compensation Analysis and Reporting' database was searched to identify all reported injuries sustained during load carriage events. Key search terms were employed and narrative description fields were interrogated to increase data accuracy.

RESULTS

A total of 1,954 injury records were extracted from the database. Of these, 404 injuries were attributed to load carriage. The majority of these load carriage injuries involved either the lower limb or back, with bones and joints accounting for the most frequently reported body structures to be injured. Field activities were the leading activities being performed at the time that load carriage injuries occurred, and muscular stress was identified as the mechanism of injury for over half of reported load carriage injuries.

CONCLUSION

This study suggests that load carriage is a substantial source of injury risk to Australian Army soldiers. Physical training may fail to adequately prepare soldiers for load carriage tasks during field training exercises.

Injuries associated with the 580 km university student grand voluntary road march: focus on foot injuries

College student volunteers (n = 142) completed a 580 km road march for 21 consecutive days. Each volunteer carried a backpack that weighed 14.1 ± 1.4 kg on the average. We investigated the incidence and location of blisters associated with the road march using a foot map along with other injuries. Overall, 95.1% of the subjects (135 of 142) sustained one or more injuries. All injured subjects had foot blisters, and 18% had other foot injuries. The most common locations of blister development were the right 5th toe (61%) and the left 5th toe (57%). The little toes seem to have been subjected to the greatest friction and shearing forces. March-related injuries, excluding foot injuries, were ankle pain (12.7%), knee pain (12.7%) and Achilles tendon pain (7.7%). Six subjects (4.2%) needed extra medical treatment for more than 2 weeks prior to returning to their daily lives after completion of the march due to associated injuries. The present study observed a very high incidence rate of injuries (95.1%) associated with the 580 km university students grand road march. These injuries posed an obstacle against completion of the road march and against returning to daily life. Active preventive interventions such as physical therapy and customized reinforced shoes and education program are recommended for reducing incidence rate and severity of injuries.

Soldier occupational load carriage: a narrative review of associated injuries

This narrative review examines injuries sustained by soldiers undertaking occupational load carriage tasks. Military soldiers are required to carry increasingly heavier occupational loads. These loads have been found to increase the physiological cost to the soldier and alter their gait mechanics. Aggregated research findings suggest that the lower limbs are the most frequent anatomical site of injury associated with load carriage. While foot blisters are common, other prevalent lower limb injuries include stress fractures, knee and foot pain, and neuropathies, like digitalgia and meralgia. Shoulder neuropathies (brachial plexus palsy) and lower back injuries are not uncommon. Soldier occupational load carriage has the potential to cause injuries that impact on force generation and force sustainment. Through understanding the nature of these injuries targeted interventions, like improved physical conditioning and support to specialised organisations, can be employed.

Effect of armor and carrying load on body balance and leg muscle function

This study investigated the impact of weight and weight distribution of body armor and load carriage on static body balance and leg muscle function. A series of human performance tests were conducted with seven male, healthy, right-handed military students in seven garment conditions with varying weight and weight distributions. Static body balance was assessed by analyzing the trajectory of center of plantar pressure and symmetry of weight bearing in the feet. Leg muscle functions were assessed by analyzing the peak electromyography amplitude of four selected leg muscles during walking. Results of this study showed that uneven weight distribution of garment and load beyond an additional 9 kg impaired static body balance as evidenced by increased sway of center of plantar pressure and asymmetry of weight bearing in the feet. Added weight on non-dominant side of the body created greater impediment to static balance. Increased garment weight also elevated peak EMG amplitude in the rectus femoris to maintain body balance and in the medial gastrocnemius to increase propulsive force. Negative impacts on balance and leg muscle function with increased carrying loads, particularly with an uneven weight distribution, should be stressed to soldiers, designers, and sports enthusiasts.

Ground reaction forces and plantar pressure distribution during occasional loaded gait

This study compared the ground reaction forces (GRF) and plantar pressures between unloaded and occasional loaded gait. The GRF and plantar pressures of 60 participants were recorded during unloaded gait and occasional loaded gait (wearing a backpack that raised their body mass index to 30); this load criterion was adopted because is considered potentially harmful in permanent loaded gait (obese people). The results indicate an overall increase (absolute values) of GRF and plantar pressures during occasional loaded gait (p < 0.05); also, higher normalized (by total weight) values in the medial midfoot and toes, and lower values in the lateral rearfoot region were observed. During loaded gait the magnitude of the vertical GRF (impact and thrust maximum) decreased and the shear forces increased more than did the proportion of the load (normalized values). These data suggest a different pattern of GRF and plantar pressure distribution during occasional loaded compared to unloaded gait.

Estimating radiation effective doses from whole body computed tomography scans based on U.S. soldier patient height and weight

BACKGROUND

The purpose of this study is to explore how a patient's height and weight can be used to predict the effective dose to a reference phantom with similar height and weight from a chest abdomen pelvis computed tomography scan when machine-based parameters are unknown. Since machine-based scanning parameters can be misplaced or lost, a predictive model will enable the medical professional to quantify a patient's cumulative radiation dose.

METHODS

One hundred mathematical phantoms of varying heights and weights were defined within an x-ray Monte Carlo based software code in order to calculate organ absorbed doses and effective doses from a chest abdomen pelvis scan. Regression analysis was used to develop an effective dose predictive model. The regression model was experimentally verified using anthropomorphic phantoms and validated against a real patient population.

RESULTS

Estimates of the effective doses as calculated by the predictive model were within 10% of the estimates of the effective doses using experimentally measured absorbed doses within the anthropomorphic phantoms. Comparisons of the patient population effective doses show that the predictive model is within 33% of current methods of estimating effective dose using machine-based parameters.

CONCLUSIONS

A patient's height and weight can be used to estimate the effective dose from a chest abdomen pelvis computed tomography scan. The presented predictive model can be used interchangeably with current effective dose estimating techniques that rely on computed tomography machine-based techniques.

Plantar pressure changes after long-distance walking

PURPOSE

The popularity of long-distance walking (LDW) has increased in the last decades. However, the effects of LDW on plantar pressure distribution and foot complaints, in particular, after several days of walking, have not been studied.

METHODS

We obtained the plantar pressure data of 62 subjects who had no history of foot complaints and who walked a total distance of 199.8 km for men (n = 30) and 161.5 km for women (n = 32) during four consecutive days. Plantar pressure was measured each day after the finish (posttests I–IV) and compared with the baseline plantar pressure data, which was obtained 1 or 2 d before the march (pretest). Mean, peak, and pressure–time integral per pixel as well as the center of pressure (COP) trajectory of each foot per measurement day were calculated using the normalization method of Keijsers et al. A paired t-test with an adjusted P value was used to detect significant differences between pretest and posttest.

RESULTS

Short-term adjustment to LDW resulted in a significant decreased loading on the toes accompanied with an increased loading on the metatarsal head III–V (P < 0.001). At all stages, particularly at later stages, there was significantly more heel loading (P < 0.001). Furthermore, the COP significantly displaced in the posterior direction but not in the mediolateral direction after marching. Contact time increased slightly from 638.5 +/- 24.2 to 675.4 +/- 22.5 ms (P < 0.001).

CONCLUSIONS

The increased heel loading and decreased function of the toes found after marching indicate a change of walking pattern with less roll-off. It is argued that these changes reflect the effect of fatigue of the lower leg muscles and to avoid loading of the most vulnerable parts of the foot.

Aetiology and risk factors of musculoskeletal disorders in physically active conscripts: a follow-up study in the Finnish Defence Forces

BACKGROUND

Musculoskeletal disorders (MSDs) are the main reason for morbidity during military training. MSDs commonly result in functional impairment leading to premature discharge from military service and disabilities requiring long-term rehabilitation. The purpose of the study was to examine associations between various risk factors and MSDs with special attention to the physical fitness of the conscripts.

METHODS

Two successive cohorts of 18 to 28-year-old male conscripts (N = 944, median age 19) were followed for six months. MSDs, including overuse and acute injuries, treated at the garrison clinic were identified and analysed. Associations between MSDs and risk factors were examined by multivariate Cox's proportional hazard models.

RESULTS

During the six-month follow-up of two successive cohorts there were 1629 MSDs and 2879 health clinic visits due to MSDs in 944 persons. The event-based incidence rate for MSD was 10.5 (95% confidence interval (CI): 10.0-11.1) per 1000 person-days. Most MSDs were in the lower extremities (65%) followed by the back (18%). The strongest baseline factors associated with MSDs were poor result in the combined outcome of a 12-minute running test and back lift test (hazard ratio (HR) 2.9; 95% CI: 1.9-4.6), high waist circumference (HR 1.7; 95% CI: 1.3-2.2), high body mass index (HR 1.8; 95% CI: 1.3-2.4), poor result in a 12-minute running test (HR 1.6; 95% CI: 1.2-2.2), earlier musculoskeletal symptoms (HR 1.7; 95% CI: 1.3-2.1) and poor school success (educational level and grades combined; HR 2.0; 95% CI: 1.3-3.0). In addition, risk factors of long-term MSDs (>or=10 service days lost due to one or several MSDs) were analysed: poor result in a 12-minute running test, earlier musculoskeletal symptoms, high waist circumference, high body mass index, not belonging to a sports club and poor result in the combined outcome of the 12-minute running test and standing long jump test were strongly associated with long-term MSDs.

CONCLUSIONS

The majority of the observed risk factors are modifiable and favourable for future interventions. An appropriate intervention based on the present study would improve both aerobic and muscular fitness prior to conscript training. Attention to appropriate waist circumference and body mass index would strengthen the intervention. Effective results from well-planned randomised controlled studies are needed before initiating large-scale prevention programmes in a military environment.

Musculoskeletal injuries description of an under-recognized injury problem among military personnel

INTRODUCTION

Although injuries are recognized as a leading health problem in the military, the size of the problem is underestimated when only acute traumatic injuries are considered. Injury-related musculoskeletal conditions are common in this young, active population. Many of these involve physical damage caused by micro-trauma (overuse) in recreation, sports, training, and job performance. The purpose of this analysis was to determine the incidence of injury-related musculoskeletal conditions in the military services (2006) and describe a standardized format in which to categorize and report them.

METHODS

The subset of musculoskeletal diagnoses found to be injury-related in previous military investigations was identified. Musculoskeletal injuries among nondeployed, active duty service members in 2006 were identified from military medical surveillance data. A matrix was used to report and categorize these conditions by injury type and body region.

RESULTS

There were 743,547 injury-related musculoskeletal conditions in 2006 (outpatient and inpatient, combined), including primary and nonprimary diagnoses. In the matrix, 82% of injury-related musculoskeletal conditions were classified as inflammation/pain (overuse), followed by joint derangements (15%) and stress fractures (2%). The knee/lower leg (22%), lumbar spine (20%), and ankle/foot (13%) were leading body region categories.

CONCLUSIONS

When assessing the magnitude of the injury problem in the military services, injury-related musculoskeletal conditions should be included. When these injuries are combined with acute traumatic injuries, there are almost 1.6 million injury-related medical encounters each year. The matrix provides a standardized format to categorize these injuries, make comparisons over time, and focus prevention efforts on leading injury types and/or body regions.

The effects of a lower body exoskeleton load carriage assistive device on limits of stability and postural sway

The study investigated the effects of using a lower body prototype exoskeleton (EXO) on static limits of stability and postural sway. Measurements were taken with participants, 10 US Army enlisted men, standing on a force platform. The men were tested with and without the EXO (15 kg) while carrying military loads of 20, 40 and 55 kg. Body lean to the left and right was significantly less and postural sway excursions and maximal range of movement were significantly reduced when the EXO was used. Hurst values indicated that body sway was less random over short-term time intervals and more random over long-term intervals with the EXO than without it. Feedback to the user's balance control mechanisms most likely was changed with the EXO. The reduced sway and relatively small changes in sway with increasing load weights suggest that the EXO structure may have functioned to provide a bracing effect on the body.

Ergonomic effects of load carriage on energy cost of gradient walking

We examined the effects of load on the energy cost of walking (C(w)), being defined as the ratio of the 2-min steady-state oxygen consumption to the speed, and economical speed (ES) during level and gradient walking. Ten men walked on a treadmill at various speeds with and without a load on their back at 0% and +/-5% gradients. Significantly lower C(w) values were observed only when the load was carried on the back during level walking at slower speeds. The ES was significantly decreased by less than 5% when the load was carried on the back. Significant gradient differences were also observed in the ES in the load and no load conditions. These results would be applicable to a wider range of occupational and leisure tasks.

Low back pain and its risk indicators: a survey of 7,040 Finnish male conscripts

Studies describing risk indicators of low back pain (LBP) have focused on adults, although the roots of LBP lie in adolescence and early adulthood. The objective of the present study was to assess the lifetime occurrence and risk indicators of LBP in young adult males. The survey sample comprised 7,333 male conscripts (median age 19), of which 7,040 (96%) answered a questionnaire during the first days of their conscription. The outcome was lifetime LBP prompting at least one visit to a physician. Associations between 18 background variables and LBP were analysed by logistic regression. Altogether 894 (12.7%) respondents reported LBP. Health status was a strong determinant of LBP. The strongest individual risk indicators for LBP were having two or more other than back-related diseases diagnosed by a physician during past year (OR 2.0; 95% CI 1.6-2.5), below-average self-perceived health (OR 1.6; 95% CI 1.3-2.0) and use of smokeless tobacco (OR 1.4; 95% CI 1.2-1.7). Socioeconomic status was not associated with LBP and health behaviours only weakly. The strongest risk indicators for LBP were related to health problems. Of the socioeconomic background factors, none were associated with LBP. It is evident that LBP is associated with other health problems as well, indicating that its background may be multifactorial. This presents challenges for prevention programme planning and implementation. Longitudinal cohort studies are urgently needed to enhance understanding of adolescent risk indicators of LBP.

Skin friction blistering: computer model

BACKGROUND/PURPOSE

Friction blisters, a common injury in sports and military operations, can adversely effect or even halt performance. Given its frequency and hazardous nature, recent research efforts appear limited. Blistering can be treated as a delamination phenomenon; similar issues in materials science have been extensively investigated in theory and experiment. An obstacle in studying blistering is the difficulty of conducting experiment on humans and animals. Computer modeling thus becomes a preferred tool.

METHOD

This paper used a dynamic non-linear finite-element model with a blister-characterized structure and contact algorithm for outer materials and blister roof to investigate the effects on deformation and stress of an existing blister by changing the friction coefficient and elastic modulus of the material in contact with the blister.

RESULTS

Through the dynamics mode and harmonic frequency approach, we demonstrated that the loading frequency leads to dramatic changes of displacement and stress in spite of otherwise similar loading. Our simulations show that an increased friction coefficient does not necessarily result in an increase in either the stress on the hot spot or blister deformation; local maximum friction stress and Von Mises stress exist for some friction coefficients over the wide range examined here. In addition, the stiffness of contact material on blistering is also investigated, and no significant effects on deformation and Von Mises stress are found, again at the range used. The model and method provided here may be useful for evaluating loading environments and contact materials in reducing blistering incidents.

CONCLUSION

The coupling finite-element model can predict the effects of friction coefficient and contacting materials&apos stiffness on blister deformation and hot spot stress.

An EFE Model on Skin-Sleeve Interactions During Arm Rotation

Skin and garment constitute a dynamic contact system for human body comfort and protection. Although dermatological injuries due to fabric actions during human body movement are common, there is still no general guidance or standard for measuring or evaluating skin/garment contact interactions, especially, during intense sports. A three-dimensional explicit finite element (EFE) model combined with Augmented Lagrange algorithm (ALA) is developed to simulate interactions between skin and fabric during rotation of the arm. Normalized effective shear stresses at the interface between skin and the sleeve during the arm rotation are provided to reflect the severity of the interactions. The effects due to changes in fabric properties, fabric-skin gap, and arm rotation rate are also illustrated. It has been demonstrated from our predictions that factors such as elastic modulus, friction coefficients, density of fabric, and the initial gap between skin and fabric influence significantly the shear stress and thus the discomfort and even injury potential to skin during intensive body movement such as sports and military. Thus this study for the first time confirms quantitatively that poorly chosen fabric with inappropriate garment design renders adverse actions on human skin.

Hospitalisation for injuries among Finnish conscripts in 1990-1999

OBJECTIVE

To describe the incidence, trends and nature of hospitalisation for injuries among Finnish conscripts between 1990 and 1999.

STUDY DESIGN AND SETTING

A hospital discharge register study on the hospitalisation for injuries with a follow-up of 213509-person-years.

RESULTS

During the 10-year study period, altogether 20016 hospitalisations for injuries were registered. Over this period, the annual incidence of hospitalisation for injuries declined with 26%, from 113.3 (95% CI: 108.7-118.0) per 1000 conscripts in 1990 to 84.1 (95% CI: 80.0-88.2) in 1999. Summer and autumn were the seasons with the highest incidence rates. Half of the injuries were sprains, strains, or fractures, and in half of the injuries, the anatomical location involved was the lower limb. The leading external causes of injuries were falls (31.8%) and injuries inflicted by foreign objects or machinery (18.5%).

CONCLUSION

Although hospitalisations for injuries declined between 1990 and 1999, injuries are still an important cause of morbidity in the Finnish Defence Forces. Further studies to evaluate the risk factors and mechanisms of injuries are needed to develop effective prevention strategies.

The effect of cigarette smoking on musculoskeletal-related disability

BACKGROUND

This study describes cigarette smoking's effect on development of physical disability following initial musculoskeletal-related hospitalization.

METHODS

We followed 15,140 US Army personnel hospitalized for common musculoskeletal disorders between 1989-1996 for up to 8 years (1997) to assess risk for long-term physical disability.

RESULTS

Trends between increased smoking level and long-term disability were identified for persons with knee injuries, rotator cuff injuries, and intervertebral disc displacement. In proportional hazards models, disability was significantly associated with heavy smoking among all subjects (relative hazard (RH) = 1.21). Both heavy smokers (RH = 1.49) and light to moderate smokers (RH = 1.44) were at greater risk for disability following meniscal injuries. Excess fraction due to smoking among subjects with meniscal injuries who currently smoke was 38%.

CONCLUSIONS

Findings suggest an association between smoking and development of disability following meniscal injury. Given the high excess fraction of disability associated with smoking, other studies are needed to confirm this association.

Interventions for preventing lower limb soft-tissue injuries in runners

BACKGROUND

Overuse musculoskeletal injuries occur frequently in runners. Suggestions for prevention have focused on stretching exercises, modifying training schedules and the use of protective devices such as braces and insoles. To date, no systematic analysis of the literature on the effectiveness of these strategies in the prevention of overuse injuries has been published.

OBJECTIVES

The objective of the review was to evaluate the evidence from randomised controlled trials on the prevention of lower limb soft-tissue running injuries.

SEARCH STRATEGY

An electronic database search included The Cochrane Musculoskeletal Injuries Group specialised register (date of last search October 2000), The Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 1999), MEDLINE (from 1966), EMBASE (from 1980), SPORT Discus (1975-2000), HERACLES (1975-2000), ATLANTES (1980-1996), BIOSIS, CINAHL, SCISEARCH, Current Contents, Index To Theses and Dissertation Abstracts. Date of last search for these databses: May 2000.

SELECTION CRITERIA

Any randomised or quasi-randomised trials evaluating interventions to prevent lower limb soft-tissue running injuries.

DATA COLLECTION AND ANALYSIS

All trials fulfilling the selection criteria were assessed by two reviewers independently. Data were also extracted independently by the two reviewers using a pre-derived data extraction form. Exploratory analyses, including pooling of results from groups of trials of similar designs were undertaken, using a fixed effects model. Results were reported as relative risks (RR) with 95 per cent confidence intervals (95% CI).

MAIN RESULTS

Twelve trials with 8,806 participants were included. In one trial, a single control group was matched to three different included intervention groups. The effectiveness of stretching exercises (5 trials, 1944 participants in the intervention groups, 3159 controls), and of insoles and footwear modification (5 trials, 903 participants in the intervention groups, 3006 controls) in the prevention of lower extremity soft tissue injuries associated with running is unknown. Reducing the distance, frequency and duration of running may be effective in the prevention of lower extremity soft tissue injuries associated with running (3 trials, 514 participants in intervention groups, 1663 controls). Wearing a knee brace with a patellar support ring may be effective in the prevention of running-associated anterior knee pain (1 trial, 27 participants in the intervention group, 33 controls).

REVIEWER'S CONCLUSIONS

This review provides some evidence for the effectiveness of the modification of training schedules, but there is insufficient evidence to determine the effectiveness of stretching exercises for major lower limb muscle groups in reducing lower limb soft-tissue running injuries. More studies are required to confirm that knee braces may prevent knee pain, to clarify the role of stretching, and to quantify optimal training loads. Generalisability of the results may be limited by the intensive nature of military training (the context for most of the studies) and the inclusion of only small numbers of women.