Optimising training adaptations and performance in military environment

Superiority of High-Load vs. Low-Load Resistance Training in Military Cadets

ABSTRACT

Øfsteng, SF, Hammarström, D, Knox, S, Jøsok, Ø, Helkala, K, Koll, L, Hanestadhaugen, M, Raastad, T, Rønnestad, BR, and Ellefsen, S. Superiority of high-load vs. low-load resistance training in military cadets. J Strength Cond Res 38(9): 1584-1595, 2024-Muscle strength and power are important determinants of soldiers' performance in modern warfare. Here, we compare the efficacy of 22 weeks of whole-body resistance training with high load (HL, 10 repetitions maximum/RM) and low load (LL, 30RM) for developing maximal muscle strength and power, performance, and muscle mass in moderately trained cadets (20 ± 1 year, f; n = 5, m; n = 22). Outcome measures were assessed at baseline and at week 22, in addition to a mid-intervention assessment at week 10. Twenty-two weeks of HL led to greater increases in muscle strength (upper limb, Δ 10%, 95% CI [2.8, 17.1], p = 0.01; lower limb, Δ 9.9%, CI [1.1, 18.6], p = 0.029), jump height (Δ 5.5%, CI [1.4, 9.6], p = 0.011), and upper limb lean mass (Δ 5.2%, CI [1, 9.4], p = 0.018) compared with LL. HL and LL led to similar changes in agility, muscle endurance performance, lower limb muscle mass, and cross-sectional area in m. vastus lateralis. For all variables, training-associated changes occurred primarily during the initial 10 weeks of the intervention, including the differential responses to HL and LL. In conclusion, although 22 weeks of HL led to greater increases in lower and upper limb muscle strength, power, and upper limb lean mass than LL, the 2 load conditions led to similar improvements in agility performance and lower limb muscle mass. Our results thus indicate that both loading regimes elicit multifaceted physiological improvements important for military readiness.

Influence of the Type of Physical Training on the Physical Fitness of Army Cadets

INTRODUCTION

Military Physical Training programs represent a constant challenge for the Armed Forces to improve body composition indices and physical fitness levels. This study aimed to verify the influence of the type of training on the physical fitness and body composition of army cadets, using 2 strategies: a sports program (Athletes group) and conventional physical training (Traditional group).

MATERIALS AND METHODS

This study involved new entrant male cadets who were selected for the Athletes group (n = 243, 19.08 ± 1.23 years) or the Traditional group (n = 356, 18.89 ± 0.97 years), with assessments occurring before and after the period of training (31.4 ± 3.9 weeks). Dual-energy X-ray absorptiometry was used to measure the bone mineral content (BMC), fat mass (FM), percentage of fat mass (%FM), and lean soft tissue (LST). The physical tests evaluated the 3,000 m run (RUN), 50 m swim (SWIM), pull-ups (PULL) on the horizontal bar, push-ups (PUSH) on the ground, and abdominal flexion (SITUP).

RESULTS

Time × group interaction effects were observed for BMC (P < .001), LST (P < .023), RUN (P < .001), PULL (P = .006), PUSH (P < .001), SITUP (P = .007), and SWIM (P < .001). A significant effect of time was noted for all variables analyzed in both groups, except %FM. The Athletes group achieved better results in body composition and in PULL, PUSH, RUN, and SWIM at baseline and after the training period. The Traditional group demonstrated higher relative changes (%) after the training period in the LST (P = .001), PULL (P < .001), PUSH (P < .001), SITUP (P < .004), and SWIM (P < .001) compared to the Athletes group.

CONCLUSION

Both physical training programs improved body composition and physical performance.

The concept of cognitive readiness: potential solution and opportunity for the Malaysian army

This paper focuses on exploring the potential solution and opportunity in the development of the Malaysian Army Transformation Plan by using the concept of Cognitive Readiness (CR). Here, the concept of CR equipped the military personnel to be cognitively ready to perform their role in military operations. The main aim of the paper is to highlight the fundamental discourse of 'what is cognitive readiness' in discovering the potential solution and opportunity in the development of the Malaysian Army Transformation Plan. The paper suggests that the strategy for transformation may start at the tactical level by focusing on enhancing the military personnel's CR. The study proposed that the Malaysian Army Organization prepare the military personnel with Knowledge, Skills and Abilities (KSA). KSA are important to boost the military personnel to have a distinctive character such as thinking critically, problem-solving and decision-making to perform effectively during military operations. In this preliminary study, the paper proposed a Framework for Tactical Cognitive Readiness (TCR) as a potential solution and opportunity for the Malaysian Army.

Comparative analysis of circulating metabolomic profiles identifies shared metabolic alterations across distinct multistressor military training exercises

Military training provides insight into metabolic responses under unique physiological demands that can be comprehensively characterized by global metabolomic profiling to identify potential strategies for improving performance. This study identified shared changes in metabolomic profiles across three distinct military training exercises, varying in magnitude and type of stress. Blood samples collected before and after three real or simulated military training exercises were analyzed using the same untargeted metabolomic profiling platform. Exercises included a 2-wk survival training course (ST, n = 36), a 4-day cross-country ski march arctic training (AT, n = 24), and a 28-day controlled diet- and exercise-induced energy deficit (CED, n = 26). Log2-fold changes of greater than ±1 in 191, 121, and 64 metabolites were identified in the ST, AT, and CED datasets, respectively. Most metabolite changes were within the lipid (57-63%) and amino acid metabolism (18-19%) pathways and changes in 87 were shared across studies. The largest and most consistent increases in shared metabolites were found in the acylcarnitine, fatty acid, ketone, and glutathione metabolism pathways, whereas the largest decreases were in the diacylglycerol and urea cycle metabolism pathways. Multiple shared metabolites were consistently correlated with biomarkers of inflammation, tissue damage, and anabolic hormones across studies. These three studies of real and simulated military training revealed overlapping alterations in metabolomic profiles despite differences in environment and the stressors involved. Consistent changes in metabolites related to lipid metabolism, ketogenesis, and oxidative stress suggest a potential common metabolomic signature associated with inflammation, tissue damage, and suppression of anabolic signaling that may characterize the unique physiological demands of military training.NEW & NOTEWORTHY The extent to which metabolomic responses are shared across diverse military training environments is unknown. Global metabolomic profiling across three distinct military training exercises identified shared metabolic responses with the largest changes observed for metabolites related to fatty acids, acylcarnitines, ketone metabolism, and oxidative stress. These changes also correlated with alterations in markers of tissue damage, inflammation, and anabolic signaling and comprise a potential common metabolomic signature underlying the unique physiological demands of military training.

Detraining's Effects on Cardiorespiratory Fitness and Maximal and Explosive Strength in Army Soldiers: Does Age Matter?

PURPOSE

This study investigated the impact of four weeks of age-dependent detraining on army soldiers' cardiorespiratory fitness and maximal and explosive strength.

METHODS

Fourteen volunteer tactical athletes participated, divided into two age groups (20 to 29 and 30 to 40 years). Before and after the detraining period, we assessed their anthropometric measurements (weight, height, body mass index, fat mass, and fat-free mass), cardiorespiratory fitness (maximal oxygen uptake [VO2max] and ventilatory thresholds [VT1 and VT2]), and kinematic properties during a single-leg counter-moving jump (CMJ) test for both the dominant and non-dominant legs. Two-way ANOVA followed by the Holm-Sidak post hoc test was used.

RESULTS

The anthropometric and cardiovascular variables did not show significant differences between the groups. However, both groups exhibited a significantly reduced maximum time and speed at the VO2max. Furthermore, the flight time and maximum height during the CMJ significantly decreased in the non-dominant leg for both age groups. Notably, the dominant leg's concentric impulse (CI) significantly reduced during the CMJ, but this effect was observed only in the 30-40 age group. There were significant differences between the two age groups.

CONCLUSIONS

Our findings suggest that four weeks of detraining negatively impacts aerobic fitness and muscular strength, independently of age. However, the dominant leg may be more susceptible to detraining effects in army soldiers aged 30-40. Furthermore, as a perspective, our results strongly suggest that a detraining period could affect successful missions (aerobic performance deterioration), as well as promote a muscle imbalance between the legs, which could encourage muscle injuries and endanger combat missions.

Optimising Combat Readiness: Practical Strategies for Integrating Physiological and Psychological Resilience in Soldier Training

This narrative review examines the intricate psychophysiological interplay between cognitive functions and physical responses within military personnel engaged in combat. It elucidates the spectrum of responses elicited by symmetric and asymmetric warfare alongside specialised combat scenarios, including close-quarters and subterranean warfare. Central to this discourse is the emphasis on integrating training programs beyond physical conditioning to encompass psychological resilience and decision-making efficacy under duress. The exploration further ventures into applying advanced technologies such as virtual reality and wearable devices, highlighting their pivotal role in augmenting training outcomes and supporting soldier health. Through a detailed analysis of psychophysiological variations across different military branches of service, the narrative review advocates for bespoke training regimens and support frameworks tailored to address the unique exigencies of each service branch. Concluding observations stress the importance of evolving military training paradigms, advocating for adopting realistic, immersive training simulations that mirror the complexities of the contemporary battlefield. This synthesis aims to contribute to the ongoing discourse on optimising military training protocols and enhancing the operational readiness and well-being of armed forces personnel. This narrative review is essential for military psychologists, trainers, and policymakers, aiming to bridge the gap between theoretical knowledge and practical implementation in military training programs.

Cardiorespiratory fitness is a risk factor for lower-limb and back injury in law enforcement officers commencing their basic training: a prospective cohort study

We aimed to report the epidemiology of lower-limb and lumbosacral injuries in Police Force recruits. We performed a cohort study of Police Force recruits undergoing a six-month training program with prospective injury data collected between 2018 and 2021. Cardiorespiratory fitness was quantified by the beep-test and police-specific-functional-capacity was quantified using a specifically designed physical performance evaluation (PPE) tool. Injury frequency and prevalence were reported. Fifteen percent (n = 180) of study Police Force recruits (n = 1,181) sustained a lower-limb or lumbosacral injury. The six-month training program significantly improved cardiorespiratory fitness (p < 0.001) and functional capacity (p < 0.001). Increased cardiorespiratory fitness at baseline decreased injury risk (OR = 0.8, 95%CI: 0.66-0.97, p = 0.019). Injury rates decreased over time and females were injured significantly earlier than males (HR = 0.70, 95%CI: 0.52 to 0.95, p = 0.021). Interventions that can pre-condition Police Force recruits prior to the commencement of their basic physical training may reduce the number of lower-limb and lumbosacral injuries.

Oxidative Stress in Military Missions-Impact and Management Strategies: A Narrative Analysis

This narrative review comprehensively examines the impact of oxidative stress on military personnel, highlighting the crucial role of physical exercise and tailored diets, particularly the ketogenic diet, in minimizing this stress. Through a meticulous analysis of the recent literature, the study emphasizes how regular physical exercise not only enhances cardiovascular, cognitive, and musculoskeletal health but is also essential in neutralizing the effects of oxidative stress, thereby improving endurance and performance during long-term missions. Furthermore, the implementation of the ketogenic diet provides an efficient and consistent energy source through ketone bodies, tailored to the specific energy requirements of military activities, and significantly contributes to the reduction in reactive oxygen species production, thus protecting against cellular deterioration under extreme stress. The study also underlines the importance of integrating advanced technologies, such as wearable devices and smart sensors that allow for the precise and real-time monitoring of oxidative stress and physiological responses, thus facilitating the customization of training and nutritional regimes. Observations from this review emphasize significant variability among individuals in responses to oxidative stress, highlighting the need for a personalized approach in formulating intervention strategies. It is crucial to develop and implement well-monitored, personalized supplementation protocols to ensure that each member of the military personnel receives a regimen tailored to their specific needs, thereby maximizing the effectiveness of measures to combat oxidative stress. This analysis makes a valuable contribution to the specialized literature, proposing a detailed framework for addressing oxidative stress in the armed forces and opening new directions for future research with the aim of optimizing clinical practices and improving the health and performance of military personnel under stress and specific challenges of the military field.

Psychophysiological Responses in Soldiers during Close Combat: Implications for Occupational Health and Fitness in Tactical Populations

This study explores the psychophysiological responses and subjective exertion experiences of soldiers in simulated hand-to-hand combat, aligning these findings with established physiological benchmarks. Active military personnel were monitored for heart rate, blood lactate levels, subjective exertion, cortical arousal, and muscle strength during combat scenarios. The results showed significant increases in heart rate and blood lactate, indicating intense cardiovascular demands and a reliance on anaerobic energy systems. Contrary to these physiological changes, soldiers reported lower levels of exertion, suggesting a possible underestimation of physical effort or individual differences in perception and mental resilience to stress. Notably, a decrease in cortical arousal post-combat was observed, potentially signaling cognitive function deficits in decision-making and information processing in high-stress environments. This decline was more pronounced than typically seen in other high-stress situations, highlighting the unique cognitive demands of hand-to-hand combat. Additionally, an increase in muscle strength was noted, underscoring the physiological adaptations arising from intensive combat training. These findings provide valuable insights into the psychophysiological effects of hand-to-hand combat, emphasizing the complex interplay between physical exertion, cognitive function, and stress response in military contexts. The study underscores the need for comprehensive training strategies that address both physical and psychological aspects to enhance combat readiness and decision-making under stress.

Changes in physical performance, body composition and physical training during military operations: systematic review and meta-analysis

Systematic review and meta-analysis applying PRISMA guidelines with a PICOS format was constructed to provide an overview of changes in physical performance, body composition and physical training in soldiers during prolonged (≥ 3 months) military operations. Twenty-four studies out of the screened 4431 records filled the inclusion criteria. A small decrease in endurance performance was the most consistent finding (Hedge's g [g] - 0.21, 95% CI - 0.01 to - 0.41) while small overall increases in maximal strength of the lower (g 0.33, 95% CI 0.16-0.50) and upper body (g 0.33, 95% CI 0.19-0.46) were observed. In addition, small increases in strength endurance (push-up, g 0.34, 95% CI 0.15-0.52; sit-up g 0.26, 95% CI 0.07-0.44) were observed. The overall changes in body composition were trivial. Heterogeneity in the outcome variables varied mainly between low to moderate. Large inter-individual variations were observed in physical training volume, including decrements especially in endurance training frequency and volume. A reduction in total training load was often associated with negative changes in body composition and physical performance according to the principle of training specificity. Individuals with higher initial fitness level were more susceptible to decrements in their physical performance during operation.

Performance changes during repeated military occupational test and its associations to physical performance

The present study investigated performance changes during three runs (1 min recovery) of repeated military simulation task test (RMST) and its associations with physical performance. Voluntary male soldiers (N = 114) participated in a series of measurements of physical performance. Lower body explosive force production, anaerobic endurance and upper body strength endurance together explained 58% of the variance in the first RSMT (p < 0.001). The same variables explained the variance in the second and third runs of RSMT by 60% and 51%, but explosive force production was replaced with aerobic endurance, assessed by the 3.2 km loaded run (p < 0.001). This study demonstrated that the role of explosive power of the lower body decreased and military specific aerobic endurance increased when occupational performance was assessed under acute fatigue even during a short high-intensity test. These results may benefit tactical strength and conditioning coaches in training optimisation for improved occupational performance in military.Practioners summary: Soldiers are required to perform occupational tasks in a repeated manner with short recovery time. In the present study, the role of explosive power of the lower body decreased and military specific aerobic endurance increased when occupational performance was assessed with a repeated high-intensity task specific performance test.

High-Intensity Functional Training Induces Superior Training Adaptations Compared With Traditional Military Physical Training

ABSTRACT

Helén, J, Kyröläinen, H, Ojanen, T, Pihlainen, K, Santtila, M, Heikkinen, R, and Vaara, JP. High-intensity functional training induces superior training adaptations compared with traditional military physical training. J Strength Cond Res 37(12): 2477-2483, 2023-This study examined the effectiveness of concurrent strength and endurance training with an emphasis on high-intensity functional training (HIFT) during military service. Voluntary male conscripts (aged 18-28 years) were placed in either an experimental (EXP: n = 50-66) or a control (CON: n = 50-67) group. The training for the EXP group included HIFT using body mass, sandbags, and kettlebells. The CON group trained according to the current practice. Physical performance and body composition were assessed at baseline (PRE), at week 10 (MID), and after (POST) the 19-week training period. Significance was set at p < 0.05. The total distance covered in a 12-minute running test increased in both groups, but the change in EXP was superior to the change in CON (11.6%, ES: 0.79 vs. 5.7%, ES: 0.33; p = 0.027). Maximal strength and power characteristics increased in EXP (3.1-5.0%), whereas no improvements were observed in CON. Conscripts with the highest initial fitness showed no improvements in physical performance in either group. Body mass and waist circumference decreased in EXP, whereas CON showed an increase in muscle mass. These findings suggest that HIFT is an effective and time-efficient approach to improve soldiers' aerobic fitness during military service. For the optimal development of strength, the training equipment used may not have provided sufficient and progressive loading to yield considerable strength adaptations. More focus should be placed on sufficient intensity and volume in both strength and endurance training, especially for the most fit soldiers.

Serum Hormone Concentrations and Body Composition in Brazilian Air Force Cadets During Rainforest Survival Training

BACKGROUND

Physiological adaptations in military jungle survival training have not yet been studied. Knowledge about the relationship between the insulin-like growth factor type I (IGF-I)/insulin-like growth factor binding protein type 3 (IGFBP-3) system and survival activities in a jungle environment can improve readiness and prepare Brazilian Air Force cadets for this kind of battlefield. Our goal was to assess changes in body composition and serum concentrations of the IGF-I/IGFBP-3 system in Brazilian Air Force cadets during five-day Amazon rainforest survival training and whether differences in sex influence these variations.

METHODS

In the five-day survival training, variations in body composition and serum levels of IGF-I and IGFBP-3 were observed. The sample consisted of 14 male cadets (21.71 ± 1.64 years) and 6 female cadets (22.00 ± 1.41 years). Changes were assessed before and immediately after the survival training.

RESULTS

The male cadets' body mass (pre: 73.89 ± 8.79 kg; post: 69.57 ± 8.44 kg), body fat (pre: 11.43 ± 4.15%; post: 10.16 ± 4.19%), IGF-I serum concentrations (pre: 252 ± 72 ng/mL; post: 140 ± 42 ng/mL), and IGFBP-3 serum concentrations (pre: 4.90 ± 0.67 ng/mL; post: 4.22 ± 0.73 ng/mL) were significantly reduced (P < .01). In the female cadets, the mean body mass values (pre: 60.98 ± 8.82 kg; post: 57.91 ± 9.01 kg), body fat (pre: 19.20 ± 5.03%; post: 17.19 ± 4.77%), and IGF-I serum concentrations (pre: 202 ± 50 ng/mL; post: 108 ± 29 ng/mL) also decreased significantly (P < .01) after survival training. Finally, the cadet's sex does not affect the variations of IGF-I (P = .46) and IGFBP-3 (P = .205) serum concentrations.

CONCLUSIONS

These findings all suggest that changes in body mass and body fat, as well as variations in the IGF-I/IGFBP-3 system, corroborate the need for military readiness preparation. Equivalent changes in both sexes indicate probable equal recovery intervals after survival training.

Effects of 12-Month Training Intervention on Physical Fitness, Body Composition, and Health Markers in Finnish Navy Soldiers

BACKGROUND

Most Western adults do not meet the recommendations for sufficient activity, and obesity is a global problem. Similar trends are also seen among Western military personnel. Many successful physical training interventions have been carried out in military environments, but the interventions have been quite short term, and the training has been supervised. Therefore, the aim of this study was to investigate the effects of a 12-month voluntary motivational training intervention among the Finnish Defence Forces' (FDF) Navy soldiers.

METHODS

In total, 77 FDF Navy soldiers, serving in missile patrol boats, took part in the study. The intervention group (IG) contained 45 participants and the control group (CG) contained 32 participants. The IG was divided into four teams that carried out the intervention, while the CG took part in only the measurements.

RESULTS

Most of the participants (65%) in the IG reported that they had increased their exercise volume during the intervention, but no major beneficial impacts on the physical fitness, body composition, or health markers were observed. Nevertheless, there was a clear diversity visible between the subgroups in the IG. The team that reported the most exercise had the best motivation and the most motivated team coach and also had the most improved physical fitness and body composition results.

CONCLUSIONS

The present study points out that in military environments, long-term voluntary training interventions may not be as successful as short-term supervised interventions. The results also suggest that in voluntary training interventions among military personnel, the participants' motivation to exercise is a key factor when improving physical fitness.

Military tactical adaptive decision making during simulated military operational stress is influenced by personality, resilience, aerobic fitness, and neurocognitive function

Laboratory-based studies designed to mimic combat or military field training have consistently demonstrated deleterious effects on warfighter's physical, cognitive, and emotional performance during simulated military operational stress (SMOS).

Purpose

The present investigation sought to determine the impact of a 48-h simulated military operational stress (SMOS) on military tactical adaptive decision making, and the influence of select psychological, physical performance, cognitive, and physiological outcome measures on decision making performance.

Methods

Male (n = 48, 26.2 ± 5.5 years, 177.7 ± 6.6 cm, 84.7 ± 14.1 kg.) subjects currently serving in the U.S. military were eligible to participate in this study. Eligible subjects completed a 96-h protocol that occurred over five consecutive days and four nights. Day 2 (D2) and day 3 (D3) consisted of 48-h of SMOS wherein sleep opportunity and caloric needs were reduced to 50%. Differences in SPEAR total block score from baseline to peak stress (D3 minus D1) were calculated to assess change in military tactical adaptive decision making and groups were stratified based on increase (high adaptors) or decrease (low adaptors) of the SPEAR change score.

Results

Overall, military tactical decision-making declined 1.7% from D1 to D3 (p < 0.001). High adaptors reported significantly higher scores of aerobic capacity (p < 0.001), self-report resilience (p = 0.020), extroversion (p < 0.001), and conscientiousness (p < 0.001). at baseline compared to low adaptors, while low adaptors reported greater scores in Neuroticism (p < 0.001).

Conclusion

The present findings suggest that service members whose adaptive decision making abilities improved throughout SMOS (i.e., high adaptors) demonstrated better baseline psychological/self-reported resilience and aerobic capacity. Further, changes in adaptive decision-making were distinct from those of lower order cognitive functions throughout SMOS exposure. With the transition of future military conflicts placing higher priority on enhancing and sustaining cognitive readiness and resiliency, data presented here demonstrates the importance of measuring and categorizing baseline measures inherent to military personnel, in order to change and train one's ability to suffer less of a decline during high stress conditions.

Changes in physical performance during British Army Junior Entry, British Army Standard Entry and Royal Air Force Basic Training

INTRODUCTION

The purpose was to quantify physical performance in men and women during British Army Junior Entry (Army-JE), British Army Standard Entry (Army-SE) and Royal Air Force (RAF) basic training (BT).

DESIGN

Prospective longitudinal study.

METHODS

381 participants ((339 men and 42 women) n=141 Army-JE, n=132 Army-SE, n=108 RAF) completed a 2 km run, medicine ball throw (MBT) and isometric mid-thigh pull (MTP), pre-BT and post-BT. To examine changes in pre-BT to post-BT physical test performance, for each course, paired Student t-test and Wilcoxon test were applied to normally and non-normally distributed data, respectively, with effect sizes reported as Cohen's D and with rank biserial correlations, respectively. A one-way between-subjects analysis of variance (ANOVA) (or Welch ANOVA for non-normally distributed data) compared performance between quartiles based on test performance pre-BT. Where the main tests statistic, p value and effect sizes identified likely effect of quartile, post hoc comparisons were made using Games-Howell tests with Tukey's p value. Data are presented as mean±SD, with statistical significance set at p<0.05.

RESULTS

During BT, 2 km run time improved by 13±46 s (-2.1%±8.1%), 30±64 s (-4.8%±12.3%) and 24±27 s (-4.5%±5.1%) for Army-JE, Army-SE and RAF, respectively (all p<0.005). MBT distance increased by 0.27±0.28 m (6.8%±7.0%) for Army-JE (p<0.001) and 0.07±0.46 m (2.3%±10.9%) for Army-SE (p=0.040), but decreased by 0.08±0.27 m (-1.4%±6.0%) for RAF (p=0.002). MTP force increased by 80±281 n (10.8%±27.6%) for Army-JE (p<0.001) and did not change for Army-SE (-36±295 n, -0.7%±20.6%, p=0.144) or RAF (-9±208 n, 1.0±17.0, p=0.603). For all tests and cohorts, participants in the lowest quartile of pre-BT performance scores demonstrated greater improvements, compared with participants in the highest quartile (except Army-JE MBT, ∆% change similar between all quartiles).

CONCLUSIONS

Changes in physical performance were observed for the three fitness tests following the different BT courses, and recruits with the lowest strength and aerobic fitness experienced greatest improvements.

CADETS' MOTIVATION FOR MOTOR ACTIVITY AS AN IMPORTANT FACTOR IN IMPROVING THEIR HEALTH

OBJECTIVE

Aim: To investigate cadets' motivational priorities for physical exercises and sports in the process of their training and the dynamics of their health indicators.

PATIENTS AND METHODS

Materials and methods: The research was conducted at the National Academy of Internal Affairs in 2018-2022. The research of motivational priorities involved 372 male cadets from the 1st to the 4th instructional years aged 17 to 22. Two groups were formed to investigate the state of cadets' health: group A (n = 39) included motivated cadets who were additionally engaged in sports, group B (n = 66) was represented by insufficiently motivated cadets who undertook training according to the traditional physical education program and did not additionally engage in physical exercises and sports.

RESULTS

Results: It was found that the motivational priorities of cadets for physical exercises and sports vary depending on the instructional year. Group A cadets showed a significantly better level of health than those from group B, by 2.98 points (p ≤ 0.001) during the 4th instructional year.

CONCLUSION

Conclusions: A high level of cadets' health formed in the process of physical exercises and sports during training will contribute to the mastering of the educational program and, in the future, will ensure the effectiveness of their service activities. Therefore, the formation of cadets' conscious motivation for motor activities during training in order to improve their health is an important task of higher educational institutions.

Effects of Combined Strength and Endurance Training on Body Composition, Physical Fitness, and Serum Hormones During a 6-Month Crisis Management Operation

ABSTRACT

Pihlainen, K, Kyröläinen, H, Santtila, M, Ojanen, T, Raitanen, J, and Häkkinen, K. Effects of combined strength and endurance training on body composition, physical fitness, and serum hormones during a 6-month crisis management operation. J Strength Cond Res 36(9): 2361-2370, 2022-Very few studies have examined the impact of training interventions on soldier readiness during an international military operation. Therefore, the present study investigated the effects of combined strength and endurance training on body composition, physical performance, and hormonal status during a 6-month international military deployment consisting of typical peacekeeping tasks, e.g., patrolling, observation, and on-base duties. Soldiers ( n = 78) were randomly allocated to a control group (C) or one of 3 combined whole-body strength and endurance training groups with varying strength-to-endurance training emphasis (Es = 25/75%, SE = 50/50% or Se = 75/25% of strength/endurance training). Body composition, physical performance (3000-m run, standing long jump [SLJ], isometric maximal voluntary contraction of the lower [MVC lower] and upper extremities [MVC upper ], muscle endurance tests), and selected serum hormone concentrations were determined prior to training (PRE), and after 9 (MID) and 19 (POST) weeks of training. Within- and between-group changes were analyzed using linear regression models. The average combined strength and endurance training frequency of the total subject group was 3 ± 2 training sessions per week. No changes were observed in physical performance variables in the intervention groups, whereas SLJ decreased by 1.9% in C ( p < 0.05). Maximal voluntary contraction lower increased by 12.8% in the combined intervention group ( p < 0.05), and this was significantly different to C ( p < 0.05). Testosterone-to-cortisol ratio increased in SE and Se ( p < 0.05), whereas no change was observed in C. The intervention groups maintained or improved their physical performance during deployment, which is beneficial for operational readiness. However, the high interindividual variation observed in training adaptations highlights the importance of training individualization during prolonged military operations.

Overnight sleeping heart rate variability of Army recruits during a 12-week basic military training course

Purpose

This study aimed to quantify sleeping heart rate (HR) and HR variability (HRV) alongside circulating tumor necrosis factor alpha (TNFα) concentrations during 12-week Basic Military Training (BMT). We hypothesised that, despite a high allostatic load, BMT would increase cardiorespiratory fitness and HRV, while lowering both sleeping HR and TNFα in young healthy recruits.

Methods

Sixty-three recruits (18–43 years) undertook ≥ 2 overnight cardiac frequency recordings in weeks 1, 8 and 12 of BMT with 4 h of beat-to-beat HR collected between 00:00 and 06:00 h on each night. Beat-to-beat data were used to derive HR and HRV metrics which were analysed as weekly averages (totalling 8 h). A fasted morning blood sample was collected in the equivalent weeks for the measurement of circulating TNFα concentrations and predicted VO₂max was assessed in weeks 2 and 8.

Results

Predicted VO₂max was significantly increased at week 8 (+ 3.3 ± 2.6 mL kg⁻¹ min⁻¹; p < 0.001). Sleeping HR (wk1, 63 ± 7 b min⁻¹) was progressively reduced throughout BMT (wk8, 58 ± 6; wk12, 55 ± 6 b min⁻¹; p < 0.01). Sleeping HRV reflected by the root mean square of successive differences (RMSSD; wk1, 86 ± 50 ms) was progressively increased (wk8, 98 ± 50; wk12, 106 ± 52 ms; p < 0.01). Fasted circulating TNFα (wk1, 9.1 ± 2.8 pg/mL) remained unchanged at wk8 (8.9 ± 2.5 pg/mL; p = 0.79) but were significantly reduced at wk12 (8.0 ± 2.4 pg/mL; p < 0.01).

Conclusion

Increased predicted VO₂max, HRV and reduced HR during overnight sleep are reflective of typical cardiorespiratory endurance training responses. These results indicate that recruits are achieving cardiovascular health benefits despite the high allostatic load associated with the 12-week BMT.

Effect of Exercise Training Programs on Physical Fitness Domains in Military Personnel: A Systematic Review and Meta-Analysis

INTRODUCTION

Physical training is important to prepare soldiers for the intense occupational demands in the military. However, current physical training may not address all fitness domains crucial for optimizing physical readiness and reducing musculoskeletal injury. The effects of nontraditional military physical training on fitness domains have been inconsistently reported, which limits the design of the ideal training program for performance optimization and injury prevention in the military. The aim of this systematic review was to identify the effects of exercise training on various fitness domains (i.e., aerobic fitness, flexibility, muscular endurance, muscular power, muscular strength, and occupationally specific physical performance) that contribute to occupational performance and musculoskeletal injury risk in military personnel.

METHODS

An extensive literature search was conducted in January 2021 and was subsequently updated in July 2021 and December 2021. Included studies consisted of comparative groups of healthy military personnel performing traditional and nontraditional military physical training with at least one assessment representative of a fitness domain. Study appraisal was conducted using the PEDro scale. Meta-analysis was conducted via forest plots, standard mean difference (SMD, effect size), and intertrial heterogeneity (I2).

RESULTS

From a total of 7,350 records, 15 studies were identified as eligible for inclusion in this review, with a total of 1,613 participants. The average study quality via the PEDro score was good (5.3/10; range 4/10 to 6/10). Nontraditional military physical training resulted in greater posttraining values for muscular endurance (SMD = 0.46; P = .004; I2 = 68%), power (SMD = 1.57; P < .0001; I2 = 90%), strength via repetition maximum testing (SMD = 1.95; P < .00001; I2 = 91%), and occupationally specific physical performance (SMD = 0.54; P = .007; I2 = 66%) compared to the traditional group. There was no significant difference for aerobic fitness (SMD = -0.31; P = .23; I2 = 86%), flexibility (SMD = 0.58; P = .16; I2 = 76%), and muscular strength via maximal voluntary contraction (SMD = 0.18; P = .28; I2 = 66%) between training groups.

CONCLUSIONS

The current systematic review identified that nontraditional military physical training had a greater posttraining effect on muscular endurance, power, strength measured via repetition maximum, and occupationally specific physical performance compared to traditional military physical training. Overall, these findings suggest that nontraditional military physical training may be beneficial in optimizing occupational performance while potentially reducing musculoskeletal injury risk.

Editorial: Military human performance optimization: Contemporary issues for sustained and improved readiness

This issue of the European Journal of Sport Science includes 8 invited state-of-the-science narrative reviews by well-established researchers in the area of military performance focused on (a) physical training; (b) musculoskeletal injury; (c) adaptive bone formation and stress fracture prevention; (d) sex differences in responses to military stress; (e) load monitoring in military settings; (g) circulating biomarkers related to resilience during military stress; (H) military nutrition research; and (I) development of military exoskeletons. Important historical, current and future scientific and research information and guidance within the context of sustained and improved military physical performance and readiness are provided. Conclusions and recommendations for protecting Soldier health and resiliency include: (1) combined physical training emphasizing higher intensity but lower volume; (2) musculoskeletal injury risk factors most supported from the literature include: female sex, prior injury and low fitness; (3) adequate sleep, vitamin D, calcium, and energy availability are all critical for creating a resilient skeleton protecting against stress fractures; (4) differences between men and women when exposed to military stress include cardiovascular strain, fat oxidation, and psychological health risk; (5) biomarkers (cortisol, epi/norepi, ILs 4, 6, 10, 18 and TNF-alpha, IGF-I, testosterone, DHEA) offer insight for internal stress; (6) monitoring physiological training load should include consideration for multiple inputs, rather than a single measure; (7) nutrition optimization includes determining operational requirements, nutritional practices and nutrient delivery strategies; and (8) future generation exoskeletons will achieve a better balance of intended movement based on individual user and interactions with internal and external constraints.

Association between movement patterns and risk of musculoskeletal injuries in navy cadets: A cohort study

OBJECTIVE

To investigate the association of movement patterns evaluated by the Dynamic Movement Assessment (DMA) with the occurrence of musculoskeletal injuries in navy cadets.

DESIGN

Cohort study.

SETTING

Participants were filmed performing the six functional tests of the DMA (deep squat, step up, single-leg squat, hop, plank and side-plank tests).

PARTICIPANTS

240 navy cadets.

MAIN OUTCOME MEASUREMENTS

Depending on the number of certain movement patterns on the Dynamic Movement Assessment (DMA), participants were classified as high, moderate, medium or low risk of developing injuries. Predictive associations between injuries and risk classification were examined using logistic regression analysis.

RESULTS

Considering sex, previous injuries and the type of secondary school as covariates, participants who were classified as high risk were not more likely to develop injuries. Non-military high school was an independent risk factor for any injuries (OR = 3.14, 95% CI [1.43,6.91]; OR = 4.57, 95% CI [1.92,10.83]), overuse injuries (OR = 2.58, 95% CI [1.05,6.30]; OR = 2.55, 95% CI [1.06, 6.14]) and acute injuries (OR = 4.88, 95% CI [1.19,19.99]), respectively. Previous musculoskeletal symptoms also increased the chance of AI (OR = 4.45, 95% CI [1.15,17.18]; OR = 5.91, 95% CI [1.13,30.88]).

CONCLUSIONS

Movement patterns evaluated by DMA are not associated with an increased risk of injuries. However, attendance of a non-military high school and previous musculoskeletal symptoms are associated with musculoskeletal injuries.

Applying Force Plate Technology to Inform Human Performance Programming in Tactical Populations

Force plate assessments, such as countermovement jumps and isometric mid-thigh pulls, examine performances (e.g., jump height, force, power) and movement strategies (e.g., asymmetries, durations), and are best suited to characterize and monitor physical capabilities, not predict injuries. To begin applying force plate technologies, users must first; (1) develop a data management plan to visualize and capture data over time; (2) select appropriate force plates for their scenario; (3) design appropriate testing protocols to ensure valid and reliable data. Force plate assessments may be added to existing testing, serve as separate testing batteries for annual profile testing to compare individuals and understand initial physical capabilities, or for more frequent testing (i.e., monthly or weekly) to monitor training-related adaptations or neuromuscular fatigue. Although these assessments inform evidence-based program designs, human performance practitioners must understand the considerations for conducting appropriate force plate testing, as well as proper visualizations and management of force plate data. Thus, the aim of this review is to provide evidence-based practices for utilizing force plates in tactical populations (e.g., military, firefighters, police). This includes best practices to implement testing for performance profiling, training adaptations, and monitoring neuromuscular fatigue and force asymmetries. Of note, due to the large amount of force-time metrics to choose from, this article provides general examples of important metrics to monitor and training recommendations based on changes to these force-time metrics, followed by specific examples in three case studies.

Physical training considerations for optimizing performance in essential military tasks

Physically demanding essential military tasks include load carriage, manual material handling and casualty evacuation. This narrative review characterizes the main physical attributes related to performance of these occupational tasks and reviews physical training intervention studies in military settings to improve performance in these military tasks. Load carriage performance requires both aerobic and neuromuscular fitness with greater emphasis on maximal strength and absolute maximal oxygen uptake, especially when carrying heavier loads. In manual material handling, maximal strength and power are strongly associated with discrete lifting, while muscular strength, muscular endurance and aerobic fitness are also associated with repetitive lifting performance. Maximal strength including grip strength, muscular endurance, absolute maximal oxygen uptake and anaerobic capacity are associated with casualty evacuation performance. The results of the present review particularly emphasize the role of muscular fitness in successful performance of the reviewed military occupational tasks. Training intervention studies indicate that load carriage performance can be effectively improved by combining strength, aerobic and specific load carriage training. Improvement in maximal lifting capacity can be achieved by strength training or combined strength and aerobic training, while strength and aerobic training alone, or their combination are effective in improving repetitive lifting, and carry tasks. Only a few studies are available for casualty evacuation and the results are inconclusive but may indicate benefits of strength or combined training. Moreover, emphasis on lower volume but higher intensity in combined training may be a feasible and effective mode to improve military occupational performance in recruits and active-duty soldiers.

Risk factors for musculoskeletal injuries in military personnel: a systematic review with meta-analysis

OBJECTIVE

To investigate the risk factors for musculoskeletal injuries in military personnel.

METHODS

A systematic literature search was carried out in August 2019 and updated in July 2020 without language or time filters. The inclusion criteria were prospective studies that investigated the risk factors for injuries in military personnel. Only risk factors analyzed by at least ten studies were selected for the meta-analysis. For data analysis, the RevMan5.3 program was used to compare the number of participants with injuries between high- or low-risk groups. The measurement of dichotomous variables was one of the selected parameters for the analysis, as well as the Mantel-Haenszel statistical method, random-effects model, and analysis with a relative risk (RR) and 95% confidence interval for the included studies.

RESULTS

A total of 2,629 studies were identified through databases. Thirty-four studies met the inclusion criteria. The groups considered at risk were the oldest [RR = 1.22; (95% CI 1.06-1.41)], with overweight or obesity [RR = 1.27; (95% CI 1.08-1, 48)], with previous injuries [RR = 1.15; (95% CI 1.01-1.30)], and with the worst performance in running tests of 1,600-3,200 m [RR = 1.87; (95% CI 1.28-2.71)]. Gender, ethnicity, and smoking were not associated with injuries. However, a subgroup analysis showed that among studies with a follow-up of fewer than 12 months, women presented RR = 2.44 (95% CI 1.65-3.60) more likely to develop injuries.

CONCLUSION

Age, overweight or obesity, previous injuries, and performance in the 1600-3200 m run are associated with an increased risk of injury in the military.

The Effects of Exercise During a 10-Week Basic Military Training Program on the Physical Fitness and the Body Composition of the Greek Naval Cadets

INTRODUCTION

The period of basic military training (BMT) is a sudden change in the individual habits of the trainees and is characterized by significant improvements in body composition such as the percentage of body fat (%BF) and lean body mass (BM). Research has shown that physical activity during the period of BMT lasting 7-10 weeks has positive effects on the physical condition and BM of cadets. The purpose of this study was to examine the effects of training combining cardiovascular conditioning, circuit strength training, swimming, team sports, and obstacle course on physical fitness and body composition during a 10-week BMT period over 4 years in the Hellenic Naval Academy (HNA).

MATERIALS AND METHODS

The sample consisted of 185 Greek cadets of the HNA (age: 18.4 ± 0.7 years, height: 1.77 ± 6.7 m, BM: 72.6 ± 9.1 kg), of which 153 was male (age: 18.3 ± 0.6 years, height: 1.79 ± 5.8 cm, BM: 75.3 ± 7.6 kg) and 32 was female (age: 18.6 ± 0.9 years, height: 1.68 ± 2.8 cm, BM: 59.9 ± 3.1 kg).The cadets participated each year for 4 years in the BMT, performing 94 training sessions, five times a week. The weekly training program included cardiovascular conditioning, circuit strength training, swimming, team sports, and obstacle course. The measurements of the participants before and after BMT were on BM, %BF, and body mass index (BMI); on the number of sit-ups (SU1), push-ups (PU1), and pull-ups (PullU1) in 1 minute; and on the 12-minute aerobic Cooper test (12-min run).

RESULTS

The results of the study showed that the BM of the cadets decreased significantly by 2.5%, (t184 = 17.591, P < .01), in men by 2.7% (t152 = 16.243, P < .01) and in women by 2.2% (t31 = 9.280, P < .01). Body mass index (BMI) decreased significantly by 2.6% (t184 = 17.681, P < .01), in men by 3.0% (t152 = 16.046, P < .01) and in women by 2.3% (t31 = 9.224, P < 0.01). Reduction in %BF in all cadets reached 11.3% (t184 = 8.134, P < .01), for men -14.8% (t152 = 8.918, P < .01) and women -2.1% (t31 = 0.860, P > .05) without significant differences between the measurements.The number of push-ups in 1 minute (PU1) significantly increased by 27.6% (t184 = -27.813, P < .01), in women by +35.6% (t31 = 13,864, P < .01). The number of sit-ups in 1 minute (SU1) significantly increased by 27.3% (t184 = -30.501, P < .01), for men +28.8% (t152 = -29.862, P < .01). The number of pull-ups in 1 minute (PullU1) reached 20.8% (t184 = -13.426, P < .01) in total, at similar levels in men (t152 = -13.918, p < .01) and women (t31 = -2.820, P < .01).On the 12-min run, the significant improvement exceeded 10.8% (t184 = -45.289, P < .01), in men by 11.1% (t152 = -45.222, P < .01) while in women by 9.0% (t31 = 15.709, P < .01).

CONCLUSIONS

The results of this study showed that 10 weeks of BMT, which combined cardiovascular conditioning, circuit strength training, swimming, team sports, and obstacle course improved the body composition, cardiorespiratory endurance, and the strength of the Greek HNA cadets.

The feasibility of implementing an evidence-based physical training program during a Canadian Armed Forces basic infantry course

OBJECTIVES

Determine the feasibility of implementing an evidence-based training program compared to a control during a basic infantry training course, and compare their effectiveness on measures of injuries and associated burdens.

DESIGN

Prospective, cohort, feasibility study.

METHODS

Infantry candidates awaiting course between 01-April-2019 and 31-March-2020 were invited to participate while those releasing from the military, awaiting occupational transfer or having >5 medical employment limitation days were excluded. Consenting participants were allocated to an infantry course prospectively scheduled to host either the evidence-based program or a control. The evidence-based program adapted modified physical training strategies from previous studies reporting reduced injuries in recruits and was supervised by certified fitness professionals, while the control was at the discretion of infantry instructors.

RESULTS

With the exception of intervention duration which was limited due to operational factors, all feasibility outcomes were met including a recruitment rate of 171/203=84.2% and an intervention adherence of 126/144=87.5%. Stakeholders reported that the evidence-based program implementation was feasible, posing a manageable demand on resources without compromising operations. Evidence-based program participants reported 68% fewer overuse musculoskeletal injuries, 296 fewer medical employment limitation days and 11 fewer attritions than control participants.

CONCLUSIONS

An evidence-based training program is feasible to implement on a basic infantry training course, and results in fewer musculoskeletal injuries, medical employment limitation days and attrition. Given these results, this program should be generalizable for a full experimental trial, and may be scaled for intermediate/advanced infantry and/or other combat occupation courses to promote an evolution towards evidence-based training.

Effects of Task-Specific and Strength Training on Simulated Military Task Performance in Soldiers

A soldier’s occupational physical task requirements are diverse and varied. However, the type of physical training that most effectively improves soldiers’ occupational task requirements has not been studied previously. The purpose of this study was to determine the important strength characteristics for soldiers during a repeated simulated military task course, and the type of training that may be effective to improve these abilities during a specialized military training period. Forty-two (n = 42) soldiers participated in the study. They were divided into three training groups; a soldier task-specific training group (TSG, n = 17), a strength training group (STG, n = 15), and a control group (CON, n = 10). Participants were measured before (PRE), middle (MID) and after (POST) the 12-week training intervention for strength performance and simulated military task test. Simulated military task performance improved significantly in TSG and STG between the PRE and MID measurements (from 9.4 to 15.7%). TSG and STG improved in various spilt times, especially in strength tasks; casualty drag (from 8.3 to 13.6%) and kettlebell carry (from 13.2 to 22.4%) between the PRE and MID measurements. The present study showed that both the training of TSG and STG were more effective than the training of CON (control group) in terms of improving the performance in the repeated simulated military task course. The present study showed that training of TSG was as effective as STG to improve repeated simulated military task course time. Therefore, an optimal training combination should include high-intensity simulated military task field training and strength training programmed with consideration of the military training phase and environmental possibilities.

United States university-based officer training and its influence on physical assessment test performance

INTRODUCTION

Cadets participating in Reserve Officers' Training Corp (ROTC) at US universities undergo both Army Physical Fitness Test (APFT) and Occupational Physical Assessment Test (OPAT) evaluations prior to commissioning. The current study examined the relationship between ROTC physical training (PT) attendance and performance in the APFT and OPAT, and characterised physical activity of cadets outside of PT.

METHODS

Twenty-six cadets' (21 males; age=20.81±2.48 years; height=171.16±8.62 cm; body mass=75.49±13.17 kg; body mass index=25.68±3.37 kg/m²) PT attendance, and diagnostic (week 1) and record (week 13) OPAT and APFT scores were documented. Paired samples t-tests evaluated differences in APFT and OPAT scores between the diagnostic and record tests. Pearson correlations were utilised to determine if a relationship existed between PT attendance and test performance. Participating cadets also completed monthly self-reported physical activity questionnaire (September, October, November); findings were reported using descriptive statistics.

RESULTS

Cadets attended 87% of PT sessions between OPAT administrations and 85% between APFT administrations. Cadets significantly improved the following test components: standing long jump (p=0.034), seated power throw (p=0.029), shuttle run (p=0.005), sit-ups (p=0.003) and 2-mile run (p=0.045). A significant, positive correlation was found between PT attendance and APFT sit-ups improvements (r=0.473, p=0.015). Cadets' frequently reported additional physical activity days per week (range: 2.8-3.1 aerobic, 3.2-3.8 strength/power, 2.9-3.2 core strength/endurance).

CONCLUSIONS

Regular participation in a single semester of ROTC PT was found to significantly increase cadets' scores in some, but not all, components of the APFT and OPAT. Self-reported physical activity results indicate that cadets regularly train outside of organised PT.

Changes in strength and power performance and serum hormone concentrations during 12 weeks of task-specific or strength training in conscripts

The purpose of this study was to investigate the effects of two different training programs on strength and power performance and serum hormone concentrations. A total of 104 male soldiers volunteered and took part in the 12-week training period with baseline, mid-, and post-measurements of body composition, muscle strength, lower and upper body power, and blood samples to determine serum hormone concentrations. The mean (±SD) age of subjects was 20 ± 1 years, height 180 ± 6 cm and body mass 72.4 ± 8.8 kg. The subjects were divided into three different training groups: soldier task-specific training (TS), strength training (ST), and control (CON). Each group had a total of 18 training sessions during the 12-week study. In the muscle strength tests, most improvements could be observed in the TS and ST groups, especially, during the first weeks of the training period. Maximal isometric leg extension force increased significantly by 7.9 ± 12.2% (p < .05) in the TS and 7.1 ± 12.6% (p < .05) in the ST groups between the PRE and MID, as well as between the PRE and POST measurements by 8.1 ± 12.4% (p < .05) in TS and 12.3 ± 15.3% (p < .01) in ST. Serum TES concentration increased significantly in TS between the PRE and MID (16.8 ± 33.9%) and PRE and POST (11.2 ± 16.7%) measurements. Serum COR concentrations decreased in TS between the MID and POST (-7.8 ± 10.9%) and PRE and POST (-11.0 ± 14.3%) measurements. Although the differences observed were rather minor in magnitude, training in the TS and ST groups led to greater improvements in muscle strength and power performance compared to the training in the CON group. The development of strength and/or power of the lower and upper body was greater in the TS and ST groups, which is crucial for warfighter's performance. Therefore, it is important to have a structured resistance-training program during military training to optimize the strength, power, and military-specific performance.

Differences in Training Adaptations of Endurance Performance during Combined Strength and Endurance Training in a 6-Month Crisis Management Operation

Decreases in aerobic fitness during military operations have been observed in several studies. Thus, differences in training adaptations during a 6-month crisis-management operation were compared by using the change in endurance performance as the outcome measure. Sixty-six male soldiers volunteered for the study, consisting of pre-post assessments of blood biomarkers, body composition, physical performance, and the military simulation test (MST) performance. Physical training volume was self-reported. After the follow-up, the data were divided based on individual changes in endurance performance. Endurance performance was improved in the high-responder group (HiR, n = 25) and maintained or decreased in the low-responder group (LoR n = 24). During the operation, the LoR group decreased while the HiR group increased their endurance training frequency from the pre-deployment level (Δ 28 ± 57% vs. -40 ± 62%, p = 0.004). Fat mass decreased (-7.6 ± 11.7% vs. 14.2 ± 20.4%, p < 0.001), and 1-min push-up (27.7 ± 21.9% vs. 11.7 ± 26.1%, p = 0.004) and MST performance improved (-13.6 ± 6.8% vs. -7.5 ± 6.5%, p = 0.006) more in the HiR group. No differences were observed in the changes of other physical performance test results or analyzed biomarkers. In conclusion, soldiers who were initially leaner and fitter in terms of lower body strength and power were more likely to decrease their aerobic fitness during the operation.

Effects of baseline fitness and BMI levels on changes in physical fitness during military service

OBJECTIVES

The purpose of the present study was to investigate how aerobic fitness, muscle fitness and body mass index (BMI) change in relation to their baseline levels during 6-12 months of military service.

DESIGN

Retrospective longitudinal follow-up study.

METHODS

The study group consisted of 249279 healthy young male conscripts (age 19.1±0.4 yrs.) who completed their military service between the years 2005-2015. Anthropometrics (body mass, height, BMI), aerobic fitness (12-min running test) and muscle fitness (sit-ups, push-ups, standing long jump) were measured.

RESULTS

A 12-min running test improved by 5% (107±292m), standing long jump 1% (2.1±16.2cm), 1-min sit-ups 19% (4±8 repetitions/min) and 1-min push-ups 33% (5±10 repetitions/min) (p<0.001 for all). Baseline fitness and baseline BMI levels were inversely associated with their changes (r=-0.37 to -0.47, p<0.001). Performance improved in conscripts in the lowest two baseline fitness quartiles in all tests, while it decreased in conscripts in the highest fitness quartiles. In addition, in conscripts who were obese at baseline, body mass decreased on average by 4.9±7.0kg (p<0.001).

CONCLUSIONS

On average, the physical fitness of conscripts improved during their compulsory military service. In particular, conscripts with a lower baseline fitness level or higher BMI showed the largest improvements, which may be significant findings from both a military readiness and national health perspective. However, the decline in physical performance of high-fit conscripts highlights the importance of individualization of physical training and military training load during military service.

Seasonal weather conditions affect training program efficiency and physical performance among special forces trainees: A long-term follow-up study

The purpose of the present investigation was to follow-up the effect of specific commandos' training-cycles (SCTCs) on upper-body strength resistance and running endurance performance, as well as determine whether variation in seasonal parameters has any effect on physical performance. Fourteen SCTCs were held over eight years, involving 466 participants. Participants were assigned to four subgroups according to their distribution over the seasons: summer (n = 124), autumn (n = 145), winter (n = 52) and spring (n = 145). Before and after each SCTC, four tests (maximal pull-up, push-up and sit-up repetitions in 70-seconds for muscle strength resistance) and a 5-km cross-country run (endurance) were performed. Seasonal data were continuously recorded during all SCTCs. Body mass decreased significantly (p<0.05) in all groups following SCTCs. These training-cycles induced a significant increase (p<0.05) in the 70-seconds push-ups, pull-ups and sit-ups and a decrease (p<0.01) in the 5-km cross-country running time among all trainees. The main effect of the season was present in all tests (p<0.01). With regard to the percentage of changes, the results from the 70-seconds push-up, pull-up and sit-up tests were significantly higher in winter and spring (p<0.01) compared with the two other seasons, while 5-km cross-country performance improvements were significantly higher (p<0.01) in spring and summer, compared to the two other seasons. In summary,14-week of SCTCs improved upper-body strength resistance and running endurance performance in the commandos. Improvements in strength resistance performance were greater during cool weather (winter and spring), while improvements in running endurance performance were higher during hotter (spring and summer) seasons.

High-Intensity Interval Training Is Associated With Alterations in Blood Biomarkers Related to Brain Injury

Purpose: Blood biomarkers are a useful tool to study concussion. However, their interpretation is complicated by a number of potential biological confounds, including exercise. This is particularly relevant in military and athletic settings where injury commonly occurs during physical exertion. The impact of high-intensity interval training (HIIT) on putative brain injury biomarkers remains under-examined. The purpose of this study was to observe the effects of HIIT on a panel of blood biomarkers associated with brain injury.

Methods: Eleven healthy, recreationally active males (median age = 29.0, interquartile range = 26.0–31.5) performed HIIT on a bicycle ergometer (8-12 × 60-s intervals at 100% of peak power output, interspersed by 75-s recovery at 50 W) three times/week for 2 weeks. Peripheral blood samples were collected before and immediately after HIIT during the first and last training sessions. Plasma concentrations of s100 calcium-binding protein beta (S100B), glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), brain-derived neurotrophic factor (BDNF), neurogranin (NRGN), peroxiredoxin (PRDX)-6, creatine kinase-BB isoenzyme (CKBB), visinin-like protein (VILIP)-1, von Willebrand factor (vWF), monocyte chemoattractant protein (MCP)-1, matrix metalloproteinase (MMP)-9, and total tau (T-tau) were quantitated by high-sensitivity MULTI-SPOT^® immunoassay, on the MesoScale Diagnostics electrochemiluminescence detection platform. Differences in biomarker concentrations in response to HIIT were evaluated by partial least squares discriminant analysis (PLSDA) within a repeated-measures bootstrapped framework.

Results: Ten of 12 biomarkers were increased pre-to-post HIIT; VILIP-1 remained unchanged, and GFAP was not statistically evaluated due to insufficient detectability. After 2 weeks of HIIT, T-tau was no longer significantly elevated pre-to-post HIIT, and significant attenuation was noted in the acute responses of NRGN, PRDX-6, MMP-9, and vWF. In addition, compared to session 1, session 6 pre-exercise concentrations of NSE and VILIP-1 were significantly lower and higher, respectively.

Conclusion: Blood biomarkers commonly associated with brain injury are significantly elevated in response to a single bout of HIIT. After a 2-week, six-session training protocol, this response was attenuated for some, but not all markers. While biomarkers continue to provide promise to concussion research, future studies are necessary to disentangle the common biological sequelae to both exercise and brain injury.