The Relationship Between Army Physical Fitness and Functional Capacities in Infantry Members of the Slovenian Armed Forces

The Single Leg Bridge Test does not replace handheld dynamometer hamstring tests in a clinical setting

OBJECTIVE

To examine the correlation of Single Leg Bridge Test (SLBT) scores with maximum isometric strength values obtained in handheld dynamometer (HHD) hamstring tests performed in a clinical setting.

DESIGN

Cross-sectional study.

SETTING

Physical therapy clinic.

PARTICIPANTS

Fifty healthy and physically active men.

MAIN OUTCOME MEASURES

Correlation between SLBT scores and force values found in three HHD hamstring tests: test 'A', volunteer in prone with hip in neutral position and the knee flexed at ∼90°; test 'B', volunteer in supine with hip and knee flexed at ∼90°; and test 'C', volunteer in the same position used to perform the SLBT.

RESULTS

The volunteers' SLBT score was 27.55 ± 7.81 repetitions. The SLBT scores were poorly associated with mean (r = 0.246) and peak (r = 0.321) results provided by HHD test 'A'. There were no significant correlations between the SLBT scores and mean or peak values obtained in tests 'B' and 'C' (p > 0.05). Similarly, the SLBT between-limb asymmetry was not associated with asymmetries found in HHD hamstring tests (p > 0.05).

CONCLUSIONS

HHD hamstring tests should not be replaced by the SLBT. We recommend for clinicians to applying such tests in a complementary way to assess the hamstring's functional status.

Impact of a 5-Week Individualised Training Program on Physical Performance and Measures Associated with Musculoskeletal Injury Risk in Army Personnel: A Pilot Study

OBJECTIVE

To examine the feasibility and effect of an individualised and force-plate guided training program on physical performance and musculoskeletal injury risk factors in army personnel.

DESIGN

Pre-post, randomised control.

METHODS

Fourteen male and five female Australian Army soldiers were randomised into two groups and performed 5-weeks of physical training. The control group (n = 9) completed standard, group-designed, physical training whilst the experimental group (n = 8) completed an individualised training program. Physical (push-ups, multi-stage fitness test, three repetition maximum (3RM) for squat, strict press, deadlift and floor press), occupational (weight-loaded march time), and technological assessments (two-leg and one-leg countermovement jumps (CMJ), one-leg balance, one-arm plank) were conducted prior to and following the training period. Comparisons between groups and changes within groups were conducted via Mann-Whitney U tests.

RESULTS

Compared to the control group, the experimental group exhibited a significantly smaller improvement for weight-loaded march time (-0.7% ± 4.0% vs. -5.1% ± 3.0%, p = 0.03) and a greater improvement for deadlift-3RM (20.6% ± 11.9% vs. 8.4% ± 6.8%, p = 0.056). All other outcomes were similar between groups. Visually favourable alterations in the two-leg CMJ profile with no reports of injuries were noted for the experimental group.

CONCLUSIONS

Individualised physical training was feasible within an army setting and, for the most part, produced similar physical, occupational and technological performances to that of standard, group-designed physical training. These preliminary results provide a foundation for future research to expand upon and clarify the benefits of individualised training programs on long-term physical performance and injury risk/incidence in active combat army personnel.

Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength

Background

The single leg bridge test (SLBT) has been introduced in the sports context as a way of estimating hamstring muscle capacity for prevention and rehabilitation of hamstring strain injuries.

Purpose

The primary aim was to examine the association between SLBT scores with concentric and eccentric knee flexor peak torques. Secondarily, this study aimed examine the association of between-limb asymmetries provided by SLBT and isokinetic tests.

Study design

Cross-sectional study.

Methods

One hundred male soccer players (20±3 years) performed the SLBT and the knee flexion-extension isokinetic dynamometry evaluation (60°/s) billaterally during a single visit. SLBT score (i.e., number of repetitions until failure) and concentric and eccentric knee flexor peak torques (normalized per body mass) were considered for analysis. For both SLBT and isokinetic dynamometry, between-limb asymmetry was calculated as the percentage difference between the left limb and the right limb. Associations were assessed through Pearson's correlation coefficient.

Results

The mean SLBT score was 33.6±9.6 repetitions, concentric peak torque was 2.00±0.22 Nm/kg, and eccentric peak torque was 2.79±0.44 Nm/kg. Between-limb asymmetry was 0.4±9.6%, 1.08±8.5%, and 1.64±14.61% in SLBT, concentric, and eccentric tests, respectively. There was a poor association of SLBT score with concentric (p<0.001, r=0.275) and eccentric (p=0.002, r=0.215) peak torques. The SLBT between-limb asymmetry was poorly associated with asymmetry found in concentric peak torque asymmetry (p=0.033, r=0.213) and was not associated with eccentric peak torque asymmetry (p=0.539, r=0.062).

Conclusion

The SLBT should not be used as a clinical tool to assess the maximum strength of hamstring muscles.

Level of Evidence

Level 3.

Dimensionality Reduction Differentiates Sensitive Force-Time Characteristics from Loaded and Unloaded Conditions throughout Competitive Military Training

The purpose was to evaluate neuromuscular fatigue’s effect on unloaded and loaded countermovement jump (CMJ) force-time characteristics during high-intensity tactical training. Eighteen male and sixteen female Marines completed two maximal effort CMJs, in unloaded (PVC pipe) and loaded (10 kg weight vest and 20 kg barbell) conditions, prior to, and 24, 48, and 72 h after starting the 4-day event. The top three variables from three principal components (PC) were analyzed using mixed-effects modeling (PC1—concentric mean power, eccentric peak force, and modified reactive strength index; PC2—countermovement depth, eccentric mean power, and eccentric mean velocity; PC3—braking duration, jump height, peak power). Metrics from PC1 and PC3 were reduced across training and from both loading conditions. Metrics from PC2 were similarly affected by external loading but were less influenced by training-induced fatigue. Jump performances with the barbell and with shallower countermovement depths did not change throughout training. Thus, 20 kg loaded CMJs are stable neuromuscular measures suitable for tracking chronic training adaptations. Monitoring unloaded and 10 kg loaded CMJ performances, along with movement strategies (i.e., countermovement rates and depth), may help identify moments of accumulated fatigue to inform training and recovery adjustments and improve the sustainability of personnel.

Monitoring Neuromuscular Performance in Military Personnel

A necessarily high standard for physical readiness in tactical environments is often accompanied by high incidences of injury due to overaccumulations of neuromuscular fatigue (NMF). To account for instances of overtraining stimulated by NMF, close monitoring of neuromuscular performance is warranted. Previously validated tests, such as the countermovement jump, are useful means for monitoring performance adaptations, resiliency to fatigue, and risk for injury. Performing such tests on force plates provides an understanding of the movement strategy used to obtain the resulting outcome (e.g., jump height). Further, force plates afford numerous objective tests that are valid and reliable for monitoring upper and lower extremity muscular strength and power (thus sensitive to NMF) with less fatiguing and safer methods than traditional one-repetition maximum assessments. Force plates provide numerous software and testing application options that can be applied to military's training but, to be effective, requires the practitioners to have sufficient knowledge of their functions. Therefore, this review aims to explain the functions of force plate testing as well as current best practices for utilizing force plates in military settings and disseminate protocols for valid and reliable testing to collect key variables that translate to physical performance capacities.