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.

Effects of 34 Weeks of Military Service on Body Composition and Physical Fitness in Military Cadets of Angola

Military personnel need physical fitness to effectively carry out operational military activities within their specific field of operation. This research investigates the effects of a 34-week training program on Angolan cadets' body composition, muscle strength, and cardiorespiratory fitness. Seventy-four volunteer recruits, aged 18 to 26 years, were monitored during their eight-month military service, following an exercise program protocol comprising 12 weeks of strength training followed by 24 weeks of endurance training. Anthropometric variables, including body mass, body mass index, and fat mass, were assessed, along with cardiorespiratory fitness (VO2max), sprint performance, countermovement jump (CMJ), medicine ball throw, push-ups, and curl-ups. The physical training protocol encompassed running sessions, strength exercises, agility drills, and flexibility exercises. The initial assessment revealed gender differences in various parameters such as body mass, body fat percentage, VO2max, sprinting, countermovement jump (CMJ), medicine ball throw, and push-ups. Following the training program, changes were observed in all variables (effect size between 0.48 and 2.33, p < 0.01) for the participants. Significant interactions (sex × time) were found in body mass (F = 5.18, p = 0.03, ηp2 = 0.06), body fat percentage (F = 5.31, p < 0.01, ηp2 = 0.14), and medicine ball throw (F = 10.84, p < 0.01, ηp2 = 0.13). Specifically, males exhibited a greater reduction in body mass (females: 2.70%, males: 3.47%, p < 0.05) and a substantial improvement in ball throwing performance (females: 7.74%, males: 11.47%, p < 0.01), while females experienced a greater reduction in fat mass (females: 5.34%, males: 3.15%, p < 0.01). The physical training regimen effectively influenced body composition, particularly in enhancing strength performance among males. The integration of exercise programs with military service led to a notable reduction in fat tissue and an increase in lean tissue. Hence, the development of tailored training protocols is imperative to enhance the physical capacity and overall health of military recruits, considering sex-specific characteristics and physical attributes.

Compared Block Periodized and Non-Periodized Physical Activity Programs in Older Adults

BACKGROUND

The periodization of physical exercise to optimize objectives is common in competitive sports. However, physical exercise programs for older adults only sometimes present periodization in their programming. Therefore, this article aims to research the results of applying the sports periodized method to older adults.

METHODS

A total of 137 participants over 60 years old performed a physical exercise program; 71 participated in a multi-component non-periodized program as the Control Group (CG), and 66 participated in a program periodized in blocks as the Experimental Group (EG). The block periodization program was oriented to the development of strength and was carried out in 86 sessions thrice weekly for eight months. Anthropometric assessments were made using weight, height, Body Mass Index, and electrical bioimpedance; and functional evaluations were made through standardized tests: Short Performance Physical Battery (SPPB), Timed Up & Go (TUG), handgrip, and a two-minute stair test.

RESULTS

After the intervention, the EG significantly improved TUG, weight, and BMI. On the other hand, the CG showed significant improvements in fat weight, BMI, and the 2 min stair test. The SPPB did not show changes after the intervention.

CONCLUSION

The periodization of physical exercise for older adults does not significantly impact functional capacity in this population group.

Comparison of different periodization models on isotonic and isokinetic muscle strength and lean mass in tactical athletes

INTRODUCTION

Tactical athletes need to develop strength and lower limb lean mass (LL LM) to perform effectively. Resistance training (RT) is the most effective way to achieve these goals. Two periodization models stand out: traditional linear periodization (TLP) and daily undulating periodization (DUP).

OBJECTIVE

To verify the effect of lower limb RT with TLP and DUP on isotonic and isokinetic muscle strength and lean mass in tactical athletes.

METHOD

Thirty-five Brazilian Army military (21.57 ± 2.02 years; 81.81 ± 11.19 Kg; 177.79 ± 6.88 cm) were divided into two treatment groups and one active control group.

INTERVENTIONS

The treatment groups performed 9 weeks of supervised RT (18 sessions), consisting of free weight exercises in this order: back squat, squat lunge, deadlift, and stiff legged deadlift. Dynamic isotonic muscle strength, lean mass, and isokinetic knee extension and flexion were assessed at baseline and post treatment period.

RESULTS

There was a significant pre-post difference in dynamic isotonic muscle strength (TLP, P < 0.001; DUP, P < 0.001) and lean mass (TLP, P = 0.034; DUP, P = 0.003) of LL LM in both treatment groups. However, effect sizes (ES) and variations (%Δ) of gains were greater in the DUP group both in muscle strength (TLP, ES = 1.55, %Δ = 30.97; DUP, ES = 2.55, %Δ = 36.02), and in lean mass (TLP, ES = 0.13, %Δ = 2.07; DUP, ES = 0.44, %Δ = 2.95). For isokinetic knee flexion strength, a significant difference was found between the TLP versus CON.

CONCLUSION

Both lower limb RT periodization models provided gains in muscle strength and lean mass, with a small advantage for the DUP approach. In the isokinetic knee flexion strength, the TLP was more effective.

Twelve weeks of concurrent resistance and interval training improves military occupational task performance in men and women

In the British Army, ground close combat roles have opened to women, however, they must pass the newly developed, gender-neutral Role Fitness Tests for Soldiers (RFT(S)). Due to physiological differences between sexes, training that optimally prepares both sexes for military occupational demands and the RFT(S) is needed. The purpose of this study was to determine the efficacy of a 12-week periodized strength and power programme with concurrent interval training on RFT(S) performance and determine if performance adaptations differed between sexes. 39 recruit-aged (18-35 yrs) participants, including 21 men (29 ± 1 yrs) and 18 women (27 ± 1 yrs), completed the study. Participants performed 3 training sessions per week that included strength and power resistance training followed by interval training. Pre- to post-training, improvements were observed for seated medicine ball throw (4.5%, p < 0.001), casualty drag (29.8%, p < 0.001), single lift (8.9%, p < 0.001), water can carry (13.8%, p = 0.012), repeated lift and carry (6.5%, p < 0.001), 2-km load carriage (7.2%, p < 0.001) and 2-km run (3.2%, p = 0.021). Pre- to post-training improvements were also observed for maximal squat (27.0%, p < 0.001), bench press (8.9%, p < 0.001) and deadlift (24.6%, p < 0.001) maximal strength, but not upper body power or aerobic capacity. No differences in RFT(S) improvements were observed between sexes, however men performed better than women in all RFT(S) and physical performance measures. Concurrent resistance and interval training improves military occupational performance in men and women; however, women may need more training than men to pass the gender-neutral RFT(S).

Reliability of Force Plate Metrics During Standard Jump, Balance, and Plank Assessments in Military Personnel

INTRODUCTION

Prevention of musculoskeletal injury is vital to the readiness, performance, and health of military personnel with the use of specialized systems (e.g., force plates) to assess risk and/or physical performance of interest. This study aimed to identify the reliability of one specialized system during standard assessments in military personnel.

METHODS

Sixty-two male and ten female Australian Army soldiers performed a two-leg countermovement jump (CMJ), one-leg CMJ, one-leg balance, and one-arm plank assessments using a Sparta Science force plate system across three testing sessions. Sparta Science (e.g., total Sparta, balance and plank scores, jump height, and injury risk) and biomechanical (e.g., average eccentric rate of contraction, average concentric force, and sway velocity) variables were recorded for all sessions. Mean ± SD, intraclass correlation coefficients (ICCs), coefficient of variation, and bias and limits of agreement were calculated for all variables.

RESULTS

Mean results were similar between sessions 2 and 3 (P > .05). The relative reliability for the Sparta Science (ICC = 0.28-0.91) and biomechanical variables (ICC = 0.03-0.85) was poor to excellent. The mean absolute reliability (coefficient of variation) for Sparta Science variables was similar to or lower than that of the biomechanical variables during the CMJ (1-10% vs. 3-7%), one-leg balance (4-6% vs. 9-14%), and one-arm plank (5-7% vs. 12-17%) assessments. The mean bias for most variables was small (<5% of the mean), while the limits of agreement varied with most unacceptable (±6-87% of the mean).

CONCLUSIONS

The reliability of most Sparta Science and biomechanical variables during standard assessments was moderate to good. The typical variability in metrics documented will assist practitioners with the use of emerging technology to monitor and assess injury risk and/or training interventions in military personnel.

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

OBJECTIVE

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

DESIGN

Pre-post, randomised control.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Acute Fatigue Responses to Occupational Training in Military Personnel: A Systematic Review and Meta-Analysis

INTRODUCTION

Military personnel are required to undertake rigorous physical training to meet the unique demands of combat, often leading to high levels of physiological stress. Inappropriate recovery periods with these high levels of physical stress may result in sub-optimal training and increased risk of injury in military personnel. However, no reviews have attempted to examine the magnitude of training-induced stress following military training activities. The aim of this systematic review was to assess the magnitude of physiological stress (physical, hormonal, and immunological) following task-specific training activities in military personnel.

METHODS

An extensive literature search was conducted within CINAHL, PubMed, Scopus, SportDiscus, and Web of Science databases with 7,220 records extracted and a total of 14 studies eligible for inclusion and evaluation. Study appraisal was conducted using the Kmet scale. Meta-analysis was conducted via forest plots, with standard mean difference (SMD, effect size) and inter-trial heterogeneity (I2) calculated between before (preactivity) and after (12-96 hours postactivity) military-specific activities for biomarkers of physiological stress (muscle damage, inflammation, and hormonal) and physical performance (muscular strength and power).

RESULTS

Military training activities resulted in significant levels of muscle damage (SMD = -1.28; P = .003) and significant impairments in strength and power (SMD = 0.91; P = .008) and testosterone levels (SMD = 1.48; P = .05) up to 96 hours postactivity. There were no significant differences in inflammation (SMD = -0.70; P = .11), cortisol (SMD = -0.18; P = .81), or insulin-like growth factor 1 (SMD = 0.65; P = .07) when compared to preactivity measures.

CONCLUSIONS

These findings indicate that assessments of muscle damage, anabolic hormones like testosterone, strength, and power are effective for determining the level of acute stress following military-specific activities. With regular monitoring of these measures, appropriate recovery periods may be implemented to optimize training adaptations and occupational performance, with minimal adverse training responses in military personnel.

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.

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.

Strength-Training Periodization: No Effect on Swimming Performance in Well-Trained Adolescent Swimmers

PURPOSE

To assess the effects of periodized versus nonperiodized dry-land strength training (DLST) on indices of swimming performance in well-trained adolescent swimmers.

METHODS

Sixteen athletes (10 boys and 6 girls; age 14.9 [1.1] y) performed similar endurance training for 16 weeks (29.1 [7.5] km·wk-1). During weeks 1 to 7, all athletes additionally performed 2 or 3 times weekly whole-body DLST (3 × 6-10 repetitions at 75-85% 1-repetition maximum [1RM]). Thereafter, the DLST frequency was maintained, but athletes were stratified into periodized (experimental, n = 9) and nonperiodized (control, n = 7) DLST groups. The experimental group performed maximal (3 × 3-4 repetitions at 85-90% 1RM) and explosive DLST (throws and unloaded jumps), while in the control group, DLST was maintained.

RESULTS

Swimming time at 4 mmol·L-1 of blood lactate improved after 7 weeks in both the experimental (+2.6% [1.8%], P = .033) and the control groups (+3.2% [2.4%], P = .081) and plateaued thereafter. Ten-meter start improved in both the experimental (-3.6% [2.5%], P = .039) and the control groups (-5.1% [2.2%], P = .054) throughout the entire intervention. Both groups improved in maximal weight lifted in half-squat (experimental, +19.6% [14.9%], P = .021; control, +25.7% [18.4%], P = .054) and bench press (experimental, +14.1% [4.8%], P = .018; control, +19.3% [11.1%], P = .051). Countermovement-jump height increased only in the experimental group throughout the intervention (+19.4% [7.0%], P = .024). The associations for the pooled changes in half-squat performance and 4 mmol·L-1 of blood lactate were statistically significant (r = .560, P = .024).

CONCLUSIONS

The findings do not support the superior effects of DLST periodization in adolescent swimmers. However, the association between improvements in lower-body strength and swimming performance still indicates the importance of muscle strength in this age group.

Effects of Linear Periodization Training on Performance Gains and Injury Prevention in a Garrisoned Military Unit

PURPOSE

Performing well in combat requires military service members to be in peak physical shape. Although each branch of the United States military has fitness guidelines and assessments, there are no exact prescriptions for physical training programs. The absence of a standardised approach may lead to suboptimal physical performance and increased risk of musculoskeletal injury. To address this gap, we evaluated the feasibility of a pilot combat conditioning program based on linear periodisation.

METHODS

Twenty-nine garrisoned US Marine Corps service members (25 men, 4 women; 23.5±4.4 years) enrolled in our 11-week conditioning program that was supervised by a strength and conditioning professional. Military-specific (physical/combat fitness tests) and general (treadmill-based maximal exercise test) assessments were performed at baseline and 11 weeks. Training and injury logs were maintained throughout the duration of the program.

RESULTS

Approximately 80% (23/29) of service members completed the entire program. Cardiorespiratory fitness (Peak VO^2; +8.10±10.9%; p=0.011), upper-body strength (pull-ups; +47.0±58.2%; p<0.001) and core strength (abdominal crunches; +9.2±23.3%; p=0.029) significantly increased from pre- to post-training. No statistically significant improvement or worsening was noted in any other performance assessment measure. Eight (28%) participants reported minor musculoskeletal concerns, of which only one required medical attention (injury rate 1.3 injuries/100 person-months).

CONCLUSION

A protocolised linear periodisation training program was feasible and demonstrated improvements in fitness in a group of garrisoned Marines with low injury rates. Other military units may benefit from a similar approach.