Prevalence of musculoskeletal injuries and a proposal for neuromuscular training to prevent lower limb injuries in Brazilian Army soldiers: an observational study

Effects of Sex and Load Carried per Kilogram of Body Mass on Landing Technique

Sex differences and heavy load carriage may contribute to the high rate of musculoskeletal injury in military recruits, particularly within the female population. Thus, the purposes of this study were to determine if load influenced landing quality differently in females compared to males and if load carried per kg body mass was associated to quality of landing. Twenty-eight participants were recruited for this study (males: n = 14; females: n = 14). Participants were grouped by sex. All twenty-eight participants performed three drop-jumps (DJ) under unloaded and loaded conditions. The loaded condition included a combat helmet, tactical vest, and rucksack (22 kg). Two cameras recorded in the frontal and sagittal directions during the three DJ trials. DJ trials were scored using the LESS. There was no significant difference in LESS difference scores between males and females, t(26) = -1.014, p = 0.320, 95% CI = -2.01 to 0.68. Load carried per kg body mass (r _s = 0.401, p = 0.034) was significantly correlated to LESS rank order. The results suggest load does not significantly alter landing quality as measured by the LESS. However, participant body mass and load per kg of body may play a role in a person's ability to adapt to heavy loads.

The Effects of Firefighter Equipment and Gear on the Static and Dynamic Postural Stability of Fire Cadets

BACKGROUND

Slips, trips, falls, and jumps were the second leading cause of injuries at the fireground.

RESEARCH QUESTION

The purpose of this study was to explore the effects of firefighter equipment and gear (EQG) on postural stability and determine if load per kg of body mass (L/BM) is associated with postural stability.

METHODS

26 male fire cadets (26.15 ± 4.16 yr., 178.92 ± 6.92 cm, 86.61 ± 9.09 kg) were included in the analyses. Participants performed 3 single-leg landings (SLL) with and without EQG. The first 3 seconds of ground reaction forces following initial ground contact were used to calculate dynamic postural stability index (DPSI). Participants completed 2 static balance tasks (normal stability and limits of stability (LoS)) with and without EQG. Main outcome measures were overall LoS score (LoSS), direction-specific LoSS, and LoS distance (cm) of COP excursion (LoSD) in the anterior, posterior, right, and left directions. Separate paired-samples t-tests were run to determine the differences between load conditions for DPSI, overall LoSS, direction-specific LoSS, and LoSD in all directions. Bivariate correlations were conducted to determine the relationship of L/BM to DPSI, overall LoSS, and LoSS and LoSD in the anterior, posterior, right and left directions.

RESULTS

Due to the use of multiple statistical tests, a Bonferroni correction was used, and the alpha level of .05 was adjusted to .005. DPSI was significantly higher loaded than unloaded, t(25) = -13.965, p < .001, d = 7.032, 95% CI, -0.133 to -0.099. No other comparisons were significant. A significant strong positive correlation (r(24) = .665, p < .001) was observed between L/BM and DPSI. No other correlations were significant.

SIGNIFICANCE

This study demonstrates that firefighter EQG may significantly impact a cadet's ability to maintain postural stability while performing their duties.

Toward more reliable stability measurements in stance: recommendations for number of measurements, foot position and feedback -- a cross-sectional study among servicemen

BACKGROUND

In the military, insufficient postural stability is a risk factor for developing lower extremity injuries. Postural stability training programs are effective in preventing these injuries. However, an objective method for the measurement of postural stability in servicemen is lacking. The primary objective of this study was to assess the influence of the number of repetitions, different foot positions and real-time visual feedback on postural stability, as well as their effects on the intrasession reliability of postural stability measurements in servicemen. The secondary objective was to assess the concurrent validity of the measurements.

METHODS

Twenty healthy servicemen between 20 and 50 years of age and in active duty were eligible for this quantitative, cross-sectional study. The measurements took place on a force plate, measuring the mean velocity of the center of pressure. The participants were asked to stand as still as possible in three different foot positions (wide stance, small stance, and on one leg), five times each for 45 s each time, and the measurements were performed with and without real-time visual feedback.

RESULTS

We observed a significant main effect of foot position (P < 0.001), but not of visual feedback (P = 0.119) or repetition number (P = 0.915). Postural stability decreased in the more challenging foot positions. The ICC estimates varied from 0.809 (one repetition in wide stance) to 0.985 (five repetitions on one leg). The common variance (R²) between different foot positions without feedback varied between 0.008 (wide stance) and 0.412.

CONCLUSIONS

To yield reliable data, wide-stance measurements should be conducted three times, and small-stance measurements and measurements on one leg should be conducted two times. The scores of a measurement in a particular foot position cannot predict the scores of measurements in other foot positions.