Force and acceleration characteristics of military foot drill: implications for injury risk in recruits

Background: Foot drill involving marching and drill manoeuvres is conducted regularly during basic military recruit training. Characterising the biomechanical loading of foot drill will improve our understanding of the contributory factors to lower limb overuse injuries in recruits. Aim: Quantify and compare forces, loading rates and accelerations of British Army foot drill, within and between trained and untrained personnel. Methods: 24 trained soldiers (12 men and 12 women; TRAINED) and 12 civilian men (UNTRAINED) performed marching and five drill manoeuvres on force platforms; motion capture recorded tibial position. Peak vertical impact force (PF), peak vertical loading rate (PLR), expressed as multiples of body weight (BW) and peak tibial impact acceleration (PTA) were recorded. Results: Drill manoeuvre PF, PLR and PTA were similar, but higher in TRAINED men (PF, PLR: p<0.01; PTA: p<0.05). Peak values in TRAINED men were shown for the halt (mean (SD); PF: 6.5 (1.5) BW; PLR: 983 (333) BW/s PTA; PTA: 207 (57) m/s2) and left turn (PF: 6.6 (1.7) BW; PLR: 928 (300) BW/s; 184 (62) m/s2). Marching PF, PLR, PTA were similar between groups and lower than all drill manoeuvres (PF: 1.1–1.3 BW; PLR: 42–70 BW/s; p<0.01; PTA: 23–38 m/s2; p<0.05). Conclusions: Army foot drill generates higher forces, loading rates and accelerations than activities such as running and load carriage, while marching is comparable to moderate running (10.8 km/h). The large biomechanical loading of foot drill may contribute to the high rate of overuse injuries during initial military training, and strategies to regulate/reduce this loading should be explored

Vitamin D metabolites are associated with musculoskeletal injury in young adults: a prospective cohort study.

The relationship between vitamin D metabolites and lower body (pelvis and lower limb) overuse injury is unclear. In a prospective cohort study, we investigated the association between vitamin D metabolites and incidence of lower body overuse musculoskeletal and bone stress injury in young adults undergoing initial military training during all seasons. In 1637 men and 530 women (age, 22.6 ± 7.5 years; BMI, 24.0 ± 2.6 kg∙m−2; 94.3% white ethnicity), we measured serum 25-hydroxyvitamin D (25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)2D) by high-performance liquid chromatography tandem mass spectrometry, and 1,25-dihydroxyvitamin D (1,25(OH)2D) by immunoassay during week 1 of training. We examined whether the relationship between 25(OH)D and 1,25(OH)2D:24,25(OH)2D ratio was associated with overuse injury. During 12 weeks training, 21.0% sustained ≥1 overuse musculoskeletal injury, and 5.6% sustained ≥1 bone stress injury. After controlling for sex, BMI, 2.4 km run time, smoking, bone injury history, and Army training course (Officer, standard, or Infantry), lower body overuse musculoskeletal injury incidence was higher for participants within the second lowest versus highest quartile of 24,25(OH)2D (OR: 1.62 [95%CI 1.13–2.32; P = 0.009]) and lowest versus highest cluster of 25(OH)D and 1,25(OH)2D:24,25(OH)2D (OR: 6.30 [95%CI 1.89–21.2; P = 0.003]). Lower body bone stress injury incidence was higher for participants within the lowest versus highest quartile of 24,25(OH)2D (OR: 4.02 [95%CI 1.82–8.87; P < 0.001]) and lowest versus highest cluster of 25(OH)D and 1,25(OH)2D:24,25(OH)2D (OR: 22.08 [95%CI 3.26–149.4; P = 0.001]), after controlling for the same covariates. Greater conversion of 25(OH)D to 24,25(OH)2D, relative to 1,25(OH)2D (i.e., low 1,25(OH)2D:24,25(OH)2D), and higher serum 24,25(OH)2D were associated with a lower incidence of lower body overuse musculoskeletal and bone stress injury. Serum 24,25(OH)2D may have a role in preventing overuse injury in young adults undertaking arduous physical training

How ‘STRONG’ is the British Army?

One of six research themes outlined in the 2021 Strategic Delivery Plan for UK Defence Medical Services (DMS) Research 2021–2026 is ‘preventing and treating musculoskeletal injury (MSKI)’.1 The research priorities identified include: ‘injury prevention and prehabilitation’, ‘lower-limb injury’, ‘shortened time to return-to-service’ and ‘physical comorbidity’. The strategic development plan also identified a need for research investigating ‘factors affecting deployment suitability and how they can be assessed and mitigated’. . .

Positional Differences in Areal Bone Mineral Density and Body Composition in NCAA Division - I Football Athletes

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Bone Mineral Density and Tibial Microarchitecture Changes in Division I Male and Female Cross - Country Runners

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Structural Differences in the Tibial Metaphysis Between Female NCAA Division I Cross - Country Runners and Gymnasts

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The legacy of pregnancy: elite athletes and women in arduous occupations

Best-practice guidance and management of pregnant and postpartum elite athletes and women in arduous occupations is limited by the lack of high-quality evidence available within these populations. We have summarized the adaptations and implications of pregnancy and childbirth, proposed a novel integrative concept to address these changes, and made recommendations to progress research in this area

The Effect of 12 - weeks of Concurrent Exercise Training on Body Composition and Bone Microarchitecture

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Influence of vitamin D supplementation by sunlight or oral D3 on exercise performance

Purpose: To determine the relationship between vitamin D status and exercise performance in a large, prospective cohort study of young men and women across seasons (Study-1). Then, in a randomized, placebo-controlled trial, to investigate the effects on exercise performance of achieving vitamin D sufficiency (serum 25(OH)D ≥ 50 nmol·L-1) by a unique comparison of safe, simulated-sunlight and oral vitamin D3 supplementation in wintertime (Study-2).  Methods: In Study-1, we determined 25(OH)D relationship with exercise performance in 967 military recruits. In Study-2, 137 men received either placebo, simulated-sunlight (1.3x standard erythemal dose in T-shirt and shorts, three-times-per-week for 4-weeks and then once-per-week for 8-weeks) or oral vitamin D3 (1,000 IU[BULLET OPERATOR]day-1 for 4-weeks and then 400 IU[BULLET OPERATOR]day-1 for 8-weeks). We measured serum 25(OH)D by LC-MS/MS and endurance, strength and power by 1.5-mile run, maximum-dynamic-lift and vertical jump, respectively.  Results: In Study-1, only 9% of men and 36% of women were vitamin D sufficient during wintertime. After controlling for body composition, smoking and season, 25(OH)D was positively associated with endurance performance (P ≤ 0.01, [INCREMENT]R2 = 0.03–0.06, small f2 effect sizes): 1.5-mile run time was ~half-a-second faster for every 1 nmol·L-1 increase in 25(OH)D. No significant effects on strength or power emerged (P > 0.05). In Study-2, safe simulated-sunlight and oral vitamin D3 supplementation were similarly effective in achieving vitamin D sufficiency in almost all (97%); however, this did not improve exercise performance (P > 0.05).  Conclusion: Vitamin D status was associated with endurance performance but not strength or power in a prospective cohort study. Achieving vitamin D sufficiency via safe, simulated summer sunlight or oral vitamin D3 supplementation did not improve exercise performance in a randomized-controlled trial