Relationship of performance on the sensory organization test to landing characteristics.

Jump landing tasks have been used to assess landing characteristics and require significant sensorimotor feedback to maintain functional joint stability (FJS) throughout the task. Postural stability (PS) also requires significant sensorimotor feedback and control and would seemingly involve similar sensory feedback pathways. However, previous literature clarifying the relationship between these two processes, maintaining FJS and PS, is limited. 80 Special Tactics Operators. PS was assessed using the Sensory Organization Test (SOT). SOT variables included: Composite, Somatosensory, Visual, Vestibular, and Preference scores. Landing characteristics were assessed using motion analysis during a double-legged (DLSJ) and single-legged (SLSJ) stop jump task. Pearson's correlation coefficients were calculated to assess the relationship between SOT scores and landing characteristics (α < .05). For the DLSJ, significant correlations were found between: Composite and peak posterior ground reaction forces (-.257), Vestibular and peak knee abduction moment (-.237), and Preference and initial contact hip flexion (-.297), peak hip flexion (-.249). For the SLSJ, significant correlations were found between: Somatosensory and peak vertical ground reaction forces (-.246); Preference and initial contact hip flexion (-.295), peak hip flexion (-.262). The results indicate that the SOT may not be a sensitive enough tool to assess sensorimotor control in a healthy, athletic population.

Predicting success in the tactical air combat party training pipeline.

OBJECTIVES: To develop a statistical model that predicts the likelihood of success or failure of military training candidates using tests administered before initial skill training as inputs. METHODS: Data were acquired from candidates before the start of U.S. Air Force Tactical Air Control Party training, including (1) demographic, (2) psychological composition evaluated using Emotional Quotient Inventory, (3) physical performance capability, (4) a physical activity questionnaire, and (5) salivary fatigue biomarker index. A total of 126 candidates were tracked until they either passed or failed the training, and a total of 55 variables were used as inputs for creation of the model. RESULTS: Clustering analysis of the data revealed that only 4 of 55 variables were useful for predicting success or failure. The variables in the order of their importance are as follows: run time, number of miles run per week in the last year, level of salivary fatigue biomarker, and height. CONCLUSIONS: The results suggest that simple testing methods can identify candidates at high risk of failure.

Effects of modafinil and sleep loss on physiological parameters.

OBJECTIVE: The purpose of this study was to determine the effects of modafinil administration on physical performance, thermoregulation, and total energy expenditure (TEE) during continued wakefulness in Air Force operators. METHODS: Participants (N = 12) were randomly assigned to the modafinil or placebo group. Participants performed physical performance and testing during 72 hours of wakefulness. RESULTS: There were no differences between groups for physical performance. Oral temperature was higher for modafinil compared to placebo (36.5 +/- 0.2 degrees C versus 36.3 +/- 0.2 degrees C for modafinil and placebo, respectively, p < 0.05). Daily water turnover (8.8 +/- 1.0 L x day(-1) and 9.0 +/- 1.5 L x day(-1)) and total energy expenditure (19.4 +/- 3.7 and 19.9 +/- 2.1 MJ) were similar between the modafinil and placebo groups, respectively. CONCLUSION: modafinil did not improve physical performance. Despite elevating oral temperature, water turnover and TEE were similar between treatments. These findings suggest it is unnecessary for operators taking modafinil to carry additional fluids and/or food.

Landing Kinematics and Kinetics at the Knee During Different Landing Tasks.

CONTEXT: Several tasks have been used to examine landing biomechanics for evaluation and rehabilitation, especially as related to anterior cruciate ligament injuries. However, comparing results among studies in which different tasks were used can be difficult, and it is unclear which task may be most appropriate. OBJECTIVE: To compare lower extremity biomechanics across 5 commonly used landing tasks. DESIGN: Descriptive laboratory study. SETTING: University-operated US Air Force Special Operations Forces human performance research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 65 US Air Force Special Tactics Operators (age = 27.7 ± 5.0 years, height = 176.5 ± 5.7 cm, mass = 83.1 ± 9.1 kg). INTERVENTION(S): Kinematic and kinetic analysis of double- and single-legged drop landing, double- and single-legged stop jump, and forward jump to single-legged landing. MAIN OUTCOME MEASURE(S): Hip-, knee-, and ankle-joint kinematics; knee-joint forces and moments; and ground reaction forces (GRFs) were the dependent measures. We used repeated-measures analyses of variance or Friedman tests, as appropriate, to assess within-subject differences across tasks. RESULTS: Peak vertical GRF and peak knee-flexion angle were different among all tasks ( P < .001). Single-legged landings generated higher vertical GRF (χ2 = 244.68, P < .001) and lower peak knee-flexion values ( F4,64 = 209.33, P < .001) except for forward jump to single-legged landing, which had the second highest peak vertical GRF and the lowest peak knee-flexion value. The single-legged drop landing generated the highest vertical (χ2 = 244.68, P < .001) and posterior (χ2 = 164.46, P < .001) GRFs. Peak knee-valgus moment was higher during the double-legged drop landing (χ2 = 239.63, P < .001) but similar for all others. CONCLUSIONS: Different landing tasks elicited different biomechanical responses; no single task was best for assessing a wide range of biomechanical variables related to anterior cruciate ligament injuries. Therefore, depending on the goals of the study, using multiple assessment tasks should be considered.

Accelerometry and salivary cortisol response during Air Force Special Tactics Officer selection.

BACKGROUND: Special Tactics Officer (STO) selection is conducted to select officers to enter the combat controller training pipeline. The aims were to determine physical activity patterns, estimate energy expenditure, and identify whether return and/or unsuccessful candidates demonstrated differences in cortisol responses compared to non-selected and/or first-time attendees. METHODS: Participants completed the STO selection, consisting of 5 days of physical and mental challenges. Participants were equipped with ActiCals®, and saliva samples were collected throughout the STO selection. RESULTS: Average activity counts were 684 ± 200 counts∙min-1, with no group differences. Estimated energy expenditure was 4,105 ± 451 kcal∙day-1. Cortisol was elevated following extended physical training but returned to baseline during rest. Return candidates had significantly lower cortisol responses compared to first-timers, 0.43 ± 0.06 µg∙dl-1 versus 0.76 ± 0.18 µg∙dl-1, respectively, p < 0.05. CONCLUSIONS: An individual's salivary cortisol response to the stresses incurred during the STO selection has the potential to be incorporated into the entire picture of a candidate's performance and ability to handle stress.

Efficacy of eat-on-move ration for sustaining physical activity, reaction time, and mood.

UNLABELLED: Repeated carbohydrate feedings and caffeine have been shown to increase self-paced physical activity. Whether a field ration pack that promotes snacking of these items would enhance physical activity remains unclear. PURPOSE: Evaluate the effectiveness of a ration pack consisting of eat-on-move items to promote snacking, as well as caffeine items, as a nutritional strategy to improve performance. METHODS: Twenty-eight wildland firefighters consumed both an eat-on-move ration (first strike ration (FSR): 13.2 MJ, 420 g CHO, 665 mg caffeine daily) and entrée-based ration (meals, ready-to-eat (MRE): 11.9 MJ, 373 g CHO, 100 mg caffeine daily) for 2 d separated by 1 d. Diet order was counterbalanced. Outcome measurements included self-paced physical activity determined by actimetry, reaction time, number of eating occasions using dietary recall, and dietary intake from food wrapper collection. RESULTS: Total eating episodes were higher with FSR compared with MRE (P = 0.013; mean +/- SD: 8.2 +/- 1.3 vs 7.6 +/- 1.1 episodes x 2 d(-1)), as were 2-d energy intake (22.0 +/- 2.4 vs 18.4 +/- 2.5 MJ; P < 0.01), carbohydrate intake (698 +/- 76 vs 546 +/- 82 mg; P < 0.01), self-reported caffeine intake (347 +/- 262 vs 55 +/- 65 mg; P < 0.01), and average end-shift salivary caffeine (1.6 +/- 1.9 vs 0.7 +/- 1.0 microg x mL(-1); P < 0.01). Total activity counts were higher (P = 0.046) when consuming FSR (507,833 +/- 129,130 counts per shift) compared with MRE (443,095 +/- 142,208 counts per shift). This was accomplished by spending a greater percentage of work shift with activity counts >1000 counts x min(-1) (21 +/- 8% vs 18 +/- 6%; P = 0.01) and less percent of work shift <50 counts x min(-1) (33 +/- 10% vs 38 +/- 10%; P = 0.01). CONCLUSIONS: Delivery of energy and caffeine in a manner that promotes snacking behavior is advantageous for increasing self-selected physical activity during arduous labor.