RESUMEN
OBJECTIVES: To determine the effect of a novel low volume high intensity concurrent training regimen and warm-up on physiological performance and musculoskeletal injury in Australian recruits. DESIGN: Controlled longitudinal intervention. METHODS: Military recruits completed 12 weeks of either experimental (EXP: n=78, 6-8RM resistance loads, and high intensity intervals) or basic military (CON: n=69, usual practice) matched for total sessions and time. Endurance (3.2km 22kg-load carriage, VËO2â¯peak, multi-stage fitness test (MSFT)), 1RM strength and local muscle endurance (bench, squat, box-lift and push-ups) and power (squat jump) were assessed at Weeks 1,6,12. Body composition, physical activity (PAC·min-1) and heart rate reserve (HRR%), were assessed at Weeks 2,7,9. Musculoskeletal injury and mechanism were recorded. Two-way repeated measures ANOVA interaction (group×time), mean difference and effect size (ES) are reported p≤0.05. RESULTS: A significant interaction over 12 weeks was observed for load carriage (ES -0.30), squat jump (ES 0.65), VËO2â¯peak (ES 0.58), MSFT (ES 0.41), push-ups (ES 0.26), 1RM bench (ES 0.26), squat (ES 1.05) and box lift (ES 0.27) in EXP compared to CON. At Week 12 significantly greater squat (38.9kg), MSFT (2.1mL·kg-1·min-1), and faster load carriage (49.9s) was observed in EXP than CON, but no difference in body composition. EXP had a lower PAC·min-1 (641.1±63.1) but higher HRR% (21.8±4.0) compared to CON. EXP had a lower number of injuries (6) compared to CON (17). CONCLUSIONS: The inclusion of compound-specific resistance exercise and high intensity intervals improved physical function and was associated with reduced musculoskeletal injury.
Asunto(s)
Ejercicio Físico/fisiología , Personal Militar , Educación y Entrenamiento Físico/métodos , Resistencia Física/fisiología , Aptitud Física/fisiología , Adolescente , Adulto , Traumatismos en Atletas/prevención & control , Australia , Trastornos de Traumas Acumulados/prevención & control , Femenino , Humanos , Estudios Longitudinales , Masculino , Fuerza Muscular/fisiología , Adulto JovenRESUMEN
OBJECTIVES: To investigate the heterogeneity of physical adaptation in Australian Army recruits completing a 12-week basic military training regimen. DESIGN: A prospective research design. METHODS: Volunteer recruits (n=195) completed 12-weeks of basic military training. Recruit physical fitness was assessed at week 1, weeks 6-8 and week 12. Recruits in the upper (75th) and lower (25th) quartiles for each assessment were then analysed using a repeated measures two-way ANOVA. The relative magnitude of recruit adaptions were classified as positive response (Rpositive, ≥5%), limited response (Rlimited, >-5% to <5%) and negative response (Rnegative, ≤-5%); Chi-square analysis determined the proportional differences in the distribution of each quartile. RESULTS: An interaction (p<0.001) was observed in the lower and upper recruit quartiles for all assessments of physical fitness at each time point. After 12 weeks of military training the mean difference of the highest quartile was; 20-m multi-stage fitness test 7.4mL·kg-1·min-1, (CI:5.8:9.1), 2-min push-ups 20.1 reps, (CI:16.2:23.9), 1RM box lift 5.6kg, (CI:2.6:5.8) and load carriage 222.1s, (CI:174.7:269.4) compared to the lowest recruit quartile. The highest quartile demonstrated no improvement in 1RM box lift (-4%, -1%) and push-ups (2%, 0%) performance at weeks 6-8 and week 12 respectively. In contrast, adaptations in the lowest quartile for 1RM box lift (16%, 21%) and push-ups (46%, 46%) over the same time periods were observed. CONCLUSIONS: A significant proportion of recruits may complete basic military training with a decline in physical performance. Higher relative-intensity cardiorespiratory and resistance exercise should be considered to facilitate physical adaptation in all recruits.
Asunto(s)
Adaptación Fisiológica , Personal Militar , Aptitud Física , Adolescente , Adulto , Australia , Capacidad Cardiovascular , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Fuerza Muscular , Resistencia Física , Estudios Prospectivos , Adulto JovenRESUMEN
OBJECTIVES: Compare traditional military physical training and more contemporary physical training on catabolic and anabolic hormones and body composition in recruits undertaking basic military training (BMT). DESIGN: A prospective cross-sectional study design. METHODS: Two recruit intakes were assessed over the 12-week Australian Army BMT course. The control group (CON) comprised 40 recruits (26M/14F) and the experimental group (EXP) comprised 35 recruits (25M/10F). Hormone concentrations (IGF-I, testosterone, cortisol, SHBG) and body composition were assessed at weeks 1 and 12. The EXP group undertook a higher-load/intensity physical training regimen, while CON undertook the extant physical training program which focused on cardiovascular and muscular endurance. Total physical activity within physical training sessions was assessed during weeks 2, 6 and 9. RESULTS: There was a significant group×time interaction (p<0.01) for IGF-I and cortisol, and main effects over time (p<0.01) for IGF-I, cortisol and SHBG. There were main effects for time (p<0.05) for lean and fat mass, and these changes were associated (p<0.05) with altered hormone concentrations. Physical activity levels were approximately 50% lower in EXP than CON during physical training sessions. CONCLUSIONS: This is the first study to report a differential hormone response to contrasting physical conditioning regimen during BMT. The results indicate that the recruits who completed the EXP physical training regimen had an attenuated stress profile. This is an important observation, as any enhancement of recruit training outcomes are critical for Army noting that fundamentally, organisational capability is reliant upon the physical capability of its personnel.
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Hidrocortisona/sangre , Factor I del Crecimiento Similar a la Insulina/análisis , Personal Militar , Acondicionamiento Físico Humano/métodos , Receptores de Superficie Celular/sangre , Testosterona/sangre , Adulto , Australia , Composición Corporal , Estudios de Casos y Controles , Estudios Transversales , Tolerancia al Ejercicio/fisiología , Femenino , Humanos , Masculino , Aptitud Física/fisiología , Estudios Prospectivos , Adulto JovenRESUMEN
Substantial gains in muscle strength and hypertrophy are clearly associated with the routine performance of resistance training. What is less evident is the optimal timing of the resistance training stimulus to elicit these significant functional and structural skeletal muscle changes. Therefore, this investigation determined the impact of a single bout of resistance training performed either in the morning or evening upon acute anabolic signalling (insulin-like growth factor-binding protein-3 (IGFBP-3), myogenic index and differentiation) and catabolic processes (cortisol). Twenty-four male participants (age 21.4±1.9yrs, mass 83.7±13.7kg) with no sustained resistance training experience were allocated to a resistance exercise group (REP). Sixteen of the 24 participants were randomly selected to perform an additional non-exercising control group (CP) protocol. REP performed two bouts of resistance exercise (80% 1RM) in the morning (AM: 0800 hrs) and evening (PM: 1800 hrs), with the sessions separated by a minimum of 72 hours. Venous blood was collected immediately prior to, and 5 min after, each resistance exercise and control sessions. Serum cortisol and IGFBP-3 levels, myogenic index, myotube width, were determined at each sampling period. All data are reported as mean ± SEM, statistical significance was set at P≤0.05. As expected a significant reduction in evening cortisol concentration was observed at pre (AM: 98.4±10.5, PM: 49.8±4.4 ng/ml, P<0.001) and post (AM: 98.0±9.0, PM: 52.7±6.0 ng/ml, P<0.001) exercise. Interestingly, individual cortisol differences pre vs post exercise indicate a time-of-day effect (AM difference: -2±2.6%, PM difference: 14.0±6.7%, P = 0.03). A time-of-day related elevation in serum IGFBP-3 (AM: 3274.9 ± 345.2, PM: 3605.1 ± 367.5, p = 0.032) was also evident. Pre exercise myogenic index (AM: 8.0±0.6%, PM: 16.8±1.1%) and myotube width (AM: 48.0±3.0, PM: 71.6±1.9 µm) were significantly elevated (P<0.001) in the evening. Post exercise myogenic index was greater AM (11.5±1.6%) compared with PM (4.6±0.9%). No difference was observed in myotube width (AM: 48.5±1.5, PM: 47.8±1.8 µm) (P>0.05). Timing of resistance training regimen in the evening appears to augment some markers of hypertrophic potential, with elevated IGFBP-3, suppressed cortisol and a superior cellular environment. Further investigation, to further elucidate the time course of peak anabolic signalling in morning vs evening training conditions, are timely.
Asunto(s)
Ritmo Circadiano/fisiología , Hidrocortisona/sangre , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Músculo Esquelético/fisiología , Entrenamiento de Fuerza , Adulto , Línea Celular , Ensayo de Inmunoadsorción Enzimática , Humanos , Hipertrofia , Masculino , Músculo Esquelético/metabolismo , Cooperación del Paciente , Adulto JovenRESUMEN
Australian Army recruits are required to meet the incumbent baseline physical employment standards (PES) during basic military training. A box lift and place (BLP) assessment is included in the PES, and it assesses the ability to perform essential muscular strength tasks. Therefore, basic military training must provide sufficient training stimulus to enable recruits to achieve the baseline BLP standard. A study was undertaken to investigate changes in the performance of 1-repetition maximum BLP in male (n = 154; age, 21.4 years) and female (n = 20; age, 23.1 years) recruits over the first 8 weeks of a 12-week basic military training course. Both male and female recruits showed modest improvements (2.2 ± 5.9 kg and 3.0 ± 3.1 kg, respectively; p ≤ 0.05) in maximal BLP performance, and there were no differences between genders. The female recruits showed greater relative improvements compared with the male recruits (14.7 ± 7.8% vs. 6.5 ± 2.3%). Despite the modest improvements in BLP performance, 70% of female and 100% of male recruits achieved the baseline BLP standard (25 kg) during week 8. The 30% failure rate for female recruits, however, suggests that the basic training program should be improved. A training program that yields greater gains in muscular strength would likely increase female recruit BLP pass rates. Augmented muscular strength would also likely increase the number of recruits capable of achieving higher BLP standards for more physically demanding employment categories. A training program that yields greater improvements in muscular strength may also enable lower entry standards, thereby increasing the recruit pool.
Asunto(s)
Elevación , Personal Militar , Fuerza Muscular , Acondicionamiento Físico Humano/fisiología , Adolescente , Australia , Prueba de Esfuerzo , Femenino , Humanos , Masculino , Aptitud Física/fisiología , Evaluación de Capacidad de Trabajo , Adulto JovenRESUMEN
OBJECTIVE: The physiological demands of 15 essential, physically demanding fire-fighting tasks were investigated to identify criterion tasks for bona fide recruit selection. METHODS: A total of 51 operational firefighters participated in discrete, field-based occupational simulations, with physiological responses measured throughout. RESULTS: The most stressful tasks were identified and classified according to dominant fitness attributes and movement patterns. Three movement classes (single-sided load carriage [5 tasks], dragging loads [4 tasks], and overhead pushing and holding objects [2 tasks]) and one mandatory strength task emerged. Seven criterion tasks were identified. Load holding and carriage dominated these movement patterns, yet no task accentuated whole-body endurance. CONCLUSION: Material handling movements from each classification must appear within a physical aptitude (selection) test for it to adequately represent the breadth of tasks performed by Australian urban firefighters.