Injuries caused during military duty and leisure sport activity

1 Introduction

Military servicemen and servicewomen have to fulfill specific demands concerning their fitness level since high physical fitness is a necessary requirement for the daily routine and while on mission [1]. The physical requirements (endurance, strength, readiness) on soldiers are high [2], especially under extreme climatic conditions (hot and cold regions) or on mountain terrain [3, 4]. Over the past decades the weight of personal and protective equipment has increased [2]. Today, NATO-soldiers on mission carry more than 30 kg of equipment, sometimes over long distances on foot patrol and even during combat.

In order to increase the necessary high physical fitness, military forces have included sports and physical training into duty schedules [5–8]. Although sport activities during duty increase physical fitness, the risk of injuries and sick days remains [9]. Sport skills differ greatly between soldiers and professional sport athletes. Professional sport athletes practise over many years and with a high weekly intensity in one sport discipline. They are also a select group of athletes with the best requirements for this discipline. On the other hand, soldiers only do sport activities some hours per week and often in several different disciplines (f.e. in one week they go running and play basketball and in the next week they play soccer and go swimming). So, the training and skills of both groups are different. Therefore, results from professional sports studies cannot be transferred to the military sports training.

The aim of sport during duty is to increase physical fitness. Injury rates of 5.97 injuries per 1,000 hours (team sport) and 0.65 injuries per 1,000 hours (individual sport) have been documented [10]. Risk factors for increasing numbers of injuries are team sport [11], particular age, unfitness (i.e., low physical fitness in the army fitness test, low endurance during running test) [1, 11–13], overweight or obesity [14, 15], smoking [12, 16] and a previous injury [14, 17]. Improved physical condition has been achieved through special training programs (e.g., the Physical Readiness Training in the U.S. Army), which led to a significant reduction of injuries [1]. The overall adjusted risk of injury was 1.5 – 1.8 times higher in groups of soldiers performing traditional military physical training programs compared to groups using a Physical Readiness Training. Cost-effectiveness has been shown [18].

Although the majority of men and women in military service take part in physical activities during leisure time, it must be noted that these activities are not conducted by military regulations or instructions. The relative risk for an injury during duty sport for several sport activities is known [10, 19]. However, there is no information on how these injuries are distributed across different body parts. This specialized knowledge of injury locations is necessary for (military) physicians in order to provide adequate therapy to those who are injured.

The aims of this study were to identify the relative number of injuries for different sport activities (frequency), to determine how these injuries are distributed across the body (distribution) and to document the time needed by military servicemen and servicewomen to recover from injuries caused during duty and leisure time sports (severity of injuries).

2 Methods

Over a period of three years (January 2008 – December 2010), all sports injuries presented to the Major Medical Clinic Augustdorf, Germany, were recorded. Augustdorf is the base of the 21th Tank Brigade of the German Army with more than 4,000 soldiers. Because German military servicemen and servicewomen don’t have a normal insurance for medical treatment they have to present themselves at the Medical Clinic of their unit, where the military physician decides on the treatment or whether to consult a specialist.

During initial and all consecutive treatments, injured soldiers were required to give evidence on the type of sport activity they were engaged in at the time of injury and this information was written in the health charts of the soldier by the military physician. Every injury was treated by a military physician in regard to the individual necessary medical requirement on the basis of the guideline of best medical practices. Additional medical specialists were consulted if necessary.

The following data were recorded in a study protocol in a MS Access database: age, date of injury, kind of sport, date of first contact to a physician, number of days of unfitness for duty, diagnosis, part of the body with side (right/left). Moreover, the health charts of the soldiers were reviewed every week. The periods of absence that were recommended by the military physician were recorded. Each case was considered to be finished after the soldier returned to full duty for a consecutive period of three days.

Each injury was assigned to one of the following body parts (head, torso, shoulder, arm, elbow, forarm, hand, pelvis, hip, sexual organs, thigh, knee, lower leg, ankle joint, foot, complete body) by two authors independently from each other. In case of different classification the third author was additional involved.

Further descriptive analysis (relative number of injuries) and mean ± standard deviation (SD) on periods of absence until the soldier returned to full duty for a consecutive three-day period was undertaken. Statistical calculations were made with IBM SPSS Statistic 21.

All soldiers were informed about the aim of the study and gave an informed consent before being included in the study.

3 Results

In total, 1,273 sport injuries were recorded out of 823 soldiers: 673 during duty sports (DS) and 600 during leisure time sports (LTS).

Soldiers injured during DS were on average 23.3 ± 4.4 years old. The majority of soldiers were male (n = 663, 98.5%), 1.5% were female (n = 10). Most injuries occurred during soccer (35.2% of all injuries) and long distance running (30.2% of all injuries) (Table 1). An analysis of the injuries showed that injuries to the ankle joint (27.3% of all injuries) and knee (24.1% of all injuries) were most common. Mean days of absence overall was 14.3 ± 25.6 days. Longer periods of absence from duty were associated with injuries to the shoulder (26.1 ± 28.3 days), hand (17.0 ± 29.3 days), knee (15.7 ± 29.8 days) and ankle joint (15.6 ± 17.8 days). Injuries to the arm, due to bone fractures in three cases, resulted in the longest period of absence (Fig. 1).

Soldiers with injuries during LTS were on average the same age as soldiers with injuries during DS: 23.0 ± 3.7 years. 97.5% of the soldiers with injury during LTS were men (n = 585) and only 2.5% were women (n = 15). The majority of injuries occurred during off-duty soccer (66.0% of all injuries) and long distance running (8.3% of all injuries). A small number of injuries occurred during unusual activities, such as ice hockey, snowboarding, rowing, motocross, etc. (Table 1). Injuries to the ankle joint (22.8% of all injuries) and knee (20.3% of all injuries) were the most relevant body parts (Fig. 2). They were related to long phases of absence from duty (23.8 ± 43.1 days on average for injuries to the knee and 24.1 ± 32.1 days on average for injuries to the ankle). Injuries to the arm resulted in longer phases of recovery (on average 35.2 ± 23.4 days of absence) compared to all other injuries. In total mean days of absence overall was 16.6 ± 28.8 days. However, it must be noted that arm injuries were only a small number of injuries (1.0% of all injuries).

4 Discussion

The aims of this study were to identify the relative number of injuries for different sport activities, to determine how these injuries are distributed across the body and to document the time needed by military servicemen and servicewomen to recover from injuries caused during duty and leisure time sports. Injuries to the ankle and knee were most common. These injuries and those to the arm were associated with longer out of duty periods than injuries to other parts of the body. Since sport activities during duty and leisure time differ, military physicians need special knowledge concerning diagnosis and therapy of sport injuries and injuries caused by snowboarding and ice hockey, even if these are rare.

Duty sport activities differ from leisure sport activities not only in the number of injuries in different sport activities. It can be suppose, that the skills of the soldier also differ from sport activities that they done in their leisure time because this are preferred sport activities, to the sport activities, that they have to done during their duty time. On the other hand, duty time sport activities are always supervised by a military exercise instructor in contrast to the leisure time activities. Here the soldiers often aren’t organised and so no exercise instructor supervised the sport activities. This could be lead to more injuries during leisure time. So the conditions between duty sport and leisure sport activities are important confounder for the frequency and the severity of sportinjuries.

This study is not representative for the entire German Armed Forces or other NATO armies, as only German Army units, excluding Navy and Air Force units, were involved. Since the participation in this study was voluntarily, the results may underrepresent the real distribution of injuries. Soldiers who didn’t agree to participate in this study were not registered, therefore, a conclusion concerning the participation rate cannot be made. 274 injuries during duty sport within one year were registered in an earlier study in Augustdorf, evaluating injury rates in relation to sport duration and with a 99% of injury registration [10]. Therefore, it could be assumed that more than 70% of all injuries during DS in the three-year period were included in this study.

An influence of seasonal effects on injury frequency and physical activity is known [1, 20]. It could be possible, that this caused a shift in the presented study. Due to the fact, that the study registered injuries within three years, this effect will be low, since winter and summer months were equally included in the study. However, weather conditions have a significant influence on injury frequency and should be kept in mind when planning DS or LTS.

The majority of injured soldiers were male. This is no surprise, since the share of women in the 21th Tank Brigade and also in the German Armed Forces is low. Sex is known as a risk factor for injuries during military physical fitness training [13, 16]. The distribution of sex was not analysed in detail in this study, since the number of injured women wasso small.

Soccer and running were the sport activities associated with most of the injuries. This represented only the absolute numbers of injuries. In a one-year study at the same unit Sammito showed, that the injury rate associated with team sports was higher than for individual sports [10]. The sport activities with the highest injury rate were basketball (15.65 injuries/1,000 hours), soccer (6.20 injuries/1,000 hours) and volleyball (3.22 injuries/1,000 hours). Running only had an injury rate of 0.59 injuries/1,000 hours. Other studies also [11] described that team sport has a higher risk for injuries. Team sport with higher injury risk should therefore be avoided and team sport with lower injury risk and individual sport should be favoured in order to reduce sport injuries, especially during DS. This may reduce the number of injuries during DS.

Injuries caused during sports are of high concern for the military [21]. The high rates of injuries to the lower extremities are similar to results in the U.S. Marine Corps [22] and during the initial entry training [23]. An analysis of injuries in the US Armed Forces in 2006 has shown, that 82% of all injuries are caused by overuse [24]. Military servicemen and servicewomen with injuries to these body parts cannot perform their military tasks, especially on mission [21]. During military training prior to the beginning of out of area missions, such injuries reduce the effect of mission training significantly [25]. Although physical activities during leisure time differ from the physical activities during duty, the injuries to the body parts are similar. To reduce risk factors for injuries it is not only important to avoid team sports [10], reduce poor physical condition [1, 11], overweight and obesity [14, 26] and smoking [12, 16]; but also to educate the (military) sport instructors. Additionally, (military) physicians need specific knowledge of physical examination, treatment and rehabilitation of sport injuries. Only under such conditions the physical training will have a positive effect on the preparation for military missions.

Further studies should focus on the effectiveness of sports for increasing physical fitness without causing injuries. Injuries significantly reduce mission readiness of the individual servicemen and servicewomen, which has a negative impact on the total unit.

Conflict of interest

None to declare.