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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 Res37(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.

Supplemental Digital Content is Available in the Text.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 Res36(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 SEand 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.

Much is known about theoretical bases of different mechanical efficiency indices and effects of physiological and biomechanical factors to them. However, there are only a few studies available about practical bases and interactions between these efficiency indices, which were the aims of the present study. Fourteen physically active men (n= 12) and women (n= 2) participated in this study. From the incremental test, six different mechanical efficiency indices were calculated for cycling work: gross (GE) and net (NE) efficiencies, two work efficiencies (WE), and economy (T) at 150 W, and in addition delta efficiency (DE) using 3–5 observation points. It was found that the efficiency indices can be divided into three groups by Spearman’s rank correlation: GE, T, and NE in group I; DE and extrapolated WE in group II; and measured WE in group III. Furthermore, group II appeared to have poor reliability due to its dependence on a work-expended energy regression line, which accuracy is poorly measured by confidence interval. As efficiency indices fall naturally into three classes that do not interact with each other, it means that they measure fundamentally different aspects of mechanical efficiency. Based on problems and imprecisions with other efficiency indices, GE, or group I, seems to be the best indicator for mechanical efficiency because of its consistency and unambiguity. Based on this methodological analysis, the baseline subtractions in efficiency indices are not encouraged.

ABSTRACTThe present study investigated physiological, mental and physical performance changes during a 20-day winter military training course and the following 10-day recovery period. Fifty-eight (age 19 ± 1 years, height 182 ± 6 cm, body mass 78.5 ± 7.2 kg) male soldiers volunteered. Body composition, serum biomarker levels and performance tests were measured four times during the study. In addition, questionnaires were collected daily for subjective stress and rate of perceived exertion. The course induced significant declines in body (−3.9%, p < 0.05) and fat mass (−31.6%, p < 0.05) as well as in all assessed physical performance variables (−9.2 - −20.2%, p < 0.05), testosterone (−73.7%, p < 0.001) and IGF-1 concentrations (−43.6%, p < 0.001). At the same time, the sex hormone-binding globulin, creatine kinase, and C-reactive protein values increased significantly (46.3–1952.7%, p < 0.05). After the 10-day recovery period, the body composition and hormonal values returned to the baseline (p < 0.05), as did some physical performance variables, such as 2 min sit-ups and the evacuation test (p < 0.05). However, explosive force production in the upper and lower bodies remained unrecovered. The 20-day winter military training caused significant physiological and mental stress, as well as a drastic decline in physical performance even for highly physically fit soldiers, and the 10-day recovery period did not establish full recovery.

Evidence on the relationship between psychosocial well-being and physical activity (PA) is insufficient, especially in young adults between 18 and 29 years. Identifying protective factors for psychosocial well-being as well as factors that may promote PA behaviour in this specific age group is crucial.

Optimal diet together with good physical fitness maintains readiness and military performance during longer deployments. The purpose of this study was to describe changes in dietary macronutrient and energy intake, total physical activity and body composition during a 6-month deployment in South Lebanon. Furthermore, associations of diet macronutrient intake and physical activity on body composition were also studied.

The high acceleration (Gz) exposure among military pilots flying fighter aircraft has been associated with an increased risk for cervical and lumbar disorders. It has been suggested that an adequate level of physical performance could reduce the risk of experiencing these disorders. The Finnish Air Force has for several years used aerobic (bicycle ergometer) and muscular fitness tests (battery of five tests) in the selection process of military pilot candidates in order to evaluate their physical fitness level. The aim of the study was to determine if these selection phase tests and anthropometry measures can predispose those individuals who might be at risk of developing severe spinal disorders leading to permanent flight duty limitations later during their military pilots' career.

Previous studies have shown that military field training (MFT) has effects on warfighters' hormonal responses, neuromuscular performance, and shooting accuracy. The aim of the present study was to investigate the changes in body composition, upper and lower body strength, serum hormone concentrations of testosterone (TES) and cortisol (COR), insulin-like growth factor-1 (IGF-1), and sex hormone binding globulin (SHBG) and shooting accuracy during prolonged MFT.

Purpose: To examine whether retrospectively assessed sports participation (SP) and competitive sports (CS) at the age of 12 years is associated with mental health and health behavior in young adulthood among males.Design: A cross-sectional study using self-administered questionnaires.Setting: Conducted prior to compulsory military refresher training course in Finland allowing geographically representative sample of Finnish young men.Participants: Six hundred eighty males aged between 20 and 35 years.Measures: Mental well-being was measured with the short version of Warwick-Edinburgh Mental Well-Being Scale and mental distress with 5 items of The Short Form Helalth Survey (SF-36) scale.Analysis: Binary logistic regression models.Results: Sports participation at the age of 12 was associated with better mental health in young adulthood, with both mental well-being (odds ratio [OR] = 1.86, 95% confidence interval 1.11-3.11) and mental distress (OR = 0.61, 0.41-0.90). Age, years of education, and current physical activity were controlled. Higher level of intensity of SP and the level of CS in childhood were associated with lower level of mental distress in adulthood. No association was found between the level of CS in childhood and mental well-being in adulthood. Further, youth SP seemed to be a risk factor for increased alcohol consumption and use of snuff in adulthood.Conclusions: Despite negative outcomes related to health behavior, the findings provide support for the association between youth SP and positive mental health outcomes in adulthood among males.

Few studies have reported the amount of physical activity (PA) and its associations to physical performance of warfighters during military field training (MFT). The purpose of this study was to investigate changes in neuromuscular performance and PA among male Finnish Army conscripts during a 21-d MFT and to evaluate their recovery during 4 d after MFT.

No previous studies have investigated attitudes of the female soldiers toward physical fitness tests and physical performance requirements. The purpose of the present study was to investigate how military personnel group, age, physical fitness, and body composition are associated with female soldiers' attitudes toward fitness tests and requirements. A survey was conducted for 362 voluntary female soldiers. 76 % of them answered that the current fitness requirements are not too demanding, and 56 to 76% thought that the minimum requirements are at appropriate level for females. Nearly half (48%) of the female soldiers reported that it creates inequality when there are the same fitness standards for both genders. 12 % of the studied females had experienced bullying and 24% had experienced discrimination because of their physical fitness. Noncommissioned officers, older soldiers, overweight soldiers, and those with lower fitness thought more often that the physical fitness requirements are too high for female soldiers (p < 0.05). Lower fitness and overweight were associated with higher prevalence of being bullied and experiences of discrimination because of physical fitness (p < 0.05). The results suggest that there might be a need for a better communication about fitness requirements and targeted interventions for better integration of women in military environment.

Although the mechanisms of G-induced stresses on the spinal structure of military pilots are well understood, less is known about relationships between the intensity of physical activity, fitness, occupational musculoskeletal symptoms, and the degree of resulting disabilities. During an aeromedical examination, Finnish military pilots answered a questionnaire on their flying experience, the occurrence of flight duty-related pain, the degree of resulting disabilities, and the intensity of physical activity they conducted. 195 males were selected for further analysis. They were divided into three groups, designated high G, low G, and HQ, according to their current flight duty profile. 93% of pilots who had passed fighter lead-in training reported flight duty-induced musculoskeletal disorders. The high-G group exhibited the highest aerobic capacity (p < 0.001) and muscular fitness scores (p < 0.001). The fittest individuals suffered markedly fewer disabilities than their less fit counterparts (p = 0.005). Flight hour accumulation among the subjects in the high-G group was associated (p = 0.010) with the occurrence of flight duty-induced disabilities. The fittest pilots flew aircraft that induce the heaviest accelerations. They also reported more musculoskeletal pain than the other pilots. Yet they seemed to experience fewer disabilities, which highlights the importance of physical training in the maintenance of operational readiness.

Typical military tasks include load carriage, digging, and lifting loads. To avoid accumulation of fatigue, it is important to know the energy expenditure of soldiers during such tasks. The purpose of this study was to measure cardiorespiratory responses during military tasks in field conditions. Unloaded (M1) and loaded (M2) marching, artillery field preparation (AFP), and digging of defensive positions (D) were monitored. 15 conscripts carried additional weight of military outfit (5.4 kg) during M1, AFP, and D and during M2 full combat gear (24.4 kg). Absolute and relative oxygen uptake (VO2) and heart rate (HR) of M1 (n = 8) were 1.5 ± 0.1 L min(-1), 19.9 ± 2.7 mL kg(-1) min(-1) (42 ± 7% VO2max), and 107 ± 8 beats min(-1) (55 ± 3% HRmax), respectively. VO2 of M2 (n = 8) was 1.7 ± 0.2 L min(-1), 22.7 ± 3.4 mL kg(-1) min(-1) (47 ± 6% VO2max) and HR 123 ± 9 beats min(-1) (64 ± 4% HRmax). VO2 of AFP (n = 5) and D (n = 6) were 1.3 ± 0.3 L min(-1), 18.0 ± 3.0 (37 ± 6% VO2max), and 1.8 ± 0.4 L min(-1), 24.3 ± 5.1 mL kg(-1) min(-1) (51 ± 9% VO2max), respectively. Corresponding HR values were 99 ± 8 beats min(-1) (50 ± 3% HRmax) and 132 ± 10 beats min(-1) (68 ± 4% HRmax), respectively. The mean work intensity of soldiers was close to 50% of their maximal aerobic capacity, which has been suggested to be maximal limit of intensity for sustained work.

Predicted maximal oxygen uptake (VO2max) measurements are based on the assumption of linear relationship between heart rate or power output and oxygen consumption during various intensities. To develop more reliable predicted test for soldiers, the purpose of the present study was to compare the results of direct measurements of VO2max to respective predicted values in cycling (military fitness test). The predicted mean (+/- SD) peak oxygen uptake (VO2peak) value was 45.2 +/- 7.7 mL kg(-1) min(-1) during first week, whereas the respective direct value was 44.8 +/- 8.5 mL kg(-1) min(-1). During the ninth week, the predicted and measured mean (+/-SD) VO2max values were 47.4 +/- 6.7 mL kg(-1) min(-1) and 48.7 +/- 7.3 mL kg(-1) min(-1), respectively. The absolute differences between the methods were -0.42 mL kg(-1) min(-1) (p = 0.46) and 1.28 mL kg(-1) min(-1) (p < 0.05), which correspond to relative values of 0.9% and 2.7%, respectively. A Bland-Altman plot of measured VO2max and predicted VO2max showed no significant trend between the mean and the difference of the 2 methods either before (r = 0.14, p = 0.24) or after the basic military training period (r = 0.11, p = 0.36). Intraclass correlation coefficient varied between r = 0.82 to 0.94. In conclusion, the predicted protocol is fairly accurate (+/-3%) and reliable to predict VO2max values in male soldiers but the use for clinical purposes should be considered individually.

Introduction: This study examined the recovery patterns of hormonal, blood lipid, and hematological profiles following strenuous physical loading, continuous extreme cold exposure and energy deficit induced by a North Pole expedition. Methods: Seven men completed an 850-km North Pole expedition in temperatures varying from -3°C to -47°C. Daily energy intake was ∼23 MJ ·d-1 and was composed of ∼60%fat. Blood samples were collected 2 wk before (Pre) the expedition and after 2 wk (Post 1), and 2 mo (Post 2). Additional samples were collected on the first (R1), third (R3), and fifth (R5) return days. Results: Mean weight loss upon return was 10 kg. Energy expenditure was estimated to be 29.6 MJ ·d-1. Declines in cortisol (-237.29 nmol ·L-1), total testosterone (-5.08 nmol ·L-1), bioavailable testosterone (-0.37 nmol ·L-1) and free thyroxin (-5.82 pmol ·L-1) returned to normal values at R5 or Post 1 (P < 0.05). The increase in sex hormone-binding globulin (+17.5 nmol ·L-1) rapidly returned to the pre-expedition concentration at R3 (P < 0.05). Significantly greater values were observed at Post 1 in the lipid (high-density lipoprotein +1.86 mmol ·L-1; low-density lipoprotein +4.23 mmol ·L-1) and hematological (WBC +1.28 ·103/L; platelets +51.86 ·103/L) profiles (P < 0.05). RBC, hemoglobin, and hematocrit were all lower at Post 1 (P < 0.05). Conclusion: Although the expedition generated extreme physical stress, this was not directly reflected on hormonal recovery times as it was similar to other much less strenuous events. Despite important variations, all hormones returned to baseline values within 2 wk. Nonetheless, physical stress would appear to have more long-term effects on blood lipid and hematological profiles. [ABSTRACT FROM AUTHOR]

The purpose of the study was to examine the effects of an 8-week basic training (BT) with added strength training (ST) or endurance training (ET) on both the performance of a 3K-combat loaded run test and the acute neuromuscular and hormonal responses. All training groups improved (p < 0.001) their run-test times: ST by 12.4%, ET by 11.6%, and normal training (NT) by 10.2%. Significant acute decreases were observed in maximal isometric force of leg extensors (p < 0.01-0.05) in all subject groups following the run. Increases were observed in acute testosterone responses (p < 0.001) after the test in all groups both at pre- and post-training. However, ET and NT demonstrated lower (p < 0.001-0.05) acute post-training serum cortisol responses than ST. In conclusion, the present results indicate that within a demanding BT, the added training for ET and especially ST may be compromised in their adaptation potential due to interference from the demands of BT.

Introduction: Military personnel are often exposed to training programs and operational situations that involve multiple stressors such as caloric deficit, sleep deprivation, and prolonged physical effort, which may disturb body homeostasis, as indicated by hormonal responses. Therefore, we investigated the effects of three training regimens on serum basal hormone concentrations before and after the 8-wk basic training (BT) period, and whether possible changes in serum basal concentrations are related to changes in endurance and strength performance. Methods: Serum hormone levels were measured in 3 groups of 24 male military conscripts before and after 3 different types of training programs: normal basic training (NT); BT with added strength training (ST); and BT with added endurance training (ET). Results: ET and ST increased their maximal strength by 12.9% and glob, respectively, and their VO2max increased by 12.0% and 8.5%, but the changes did not differ significantly between the groups. Increases in serum basal testosterone concentration were observed in all groups (BT by 16.6%, ST by 16.3%, and ET by 26.6%). Serum basal cortisol concentration increased in ST by 11.1%. Serum basal thyroxine concentration decreased by 9.2% in NT, 11.9% in ST, and 10.5% in ET. Conclusions: The increases in strength, aerobic capacity, and testosterone after training indicate that the regimens were adequate to create positive training responses, especially in the ST and ET groups. On the other hand, unexpectedly low strength gains in the ST group during BT may be a consequence of too high an amount of endurance-based military training. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to examine the changes in cardiovascular performance (VO2 max) and maximal strength development during an 8-week basic training (BT) combined with emphasized endurance training (ET) or strength training (ST) among 72 conscripts. The emphasized ST and ET programs combined with BT improved VO2 max by 12.0% (p < 0.01) and 8.5% (p < 0.05), while the increase in the control group (normal training) was 13.4% (p < 0.001). Body fat and waist circumference decreased in all groups. Normal training did not increase maximal strength of leg extensors but both ST (9.1%; p < 0.05) and ET (12.9%; p < 0.01) did. In conclusion, the current BT program including a high amount of endurance training improved cardiovascular performance. However, no further improvements in VO2 max were obtained by added endurance training for three times a week. BT positively influenced body composition but BT alone was not a sufficient stimulus to increase the maximal strength of leg extensors.

KYRÖLÄINEN, H., R. KIVELÄ, S. KOSKINEN, J. MCBRIDE, J. L. ANDERSEN, T. TAKALA, S. SIPILÄ, and P. V. KOMI. Interrelationships between Muscle Structure, Muscle Strength, and Running Economy. Med. Sci. Sports Exerc., Vol. 35, No. 1, pp. 45–49, 2003.

KUITUNEN, S., P. V. KOMI, and H. KYRÖLÄINEN. Knee and ankle joint stiffness in sprint running. Med. Sci. Sports Exerc., Vol. 34, No. 1, 2002, pp. 166–173.

KYRÖLÄINEN, H., A. BELLI, and P. V. KOMI. Biomechanical factors affecting running economy. Med. Sci. Sports Exerc., Vol. 33, No. 8, 2001, pp. 1330–1337.

Experiments were carried out to test the effect of prolonged and repeated passive stretching (RPS) of the triceps surae muscle on reflex sensitivity. The results demonstrated a clear deterioration of muscle function immediately after RPS. Maximal voluntary contraction, average electromyographic activity of the gastrocnemius and soleus muscles, and zero crossing rate of the soleus muscle (recorded from 50% maximal voluntary contraction) decreased on average by 23.2, 19.9, 16.5, and 12.2%, respectively. These changes were associated with a clear immediate reduction in the reflex sensitivity; stretch reflex peak-to-peak amplitude decreased by 84.8%, and the ratio of the electrically induced maximal Hoffmann reflex to the maximal mass compound action potential decreased by 43.8%. Interestingly, a significant (P< 0.01) reduction in the stretch-resisting force of the measured muscles was observed. Serum creatine kinase activity stayed unaltered. This study presents evidence that the mechanism that decreases the sensitivity of short-latency reflexes can be activated because of RPS. The origin of this system seems to be a reduction in the activity of the large-diameter afferents, resulting from the reduced sensitivity of the muscle spindles to repeated stretch.

The mechanisms related to the acute and delayed secondary impairment of the stretch reflex function were investigated after long-lasting stretch-shortening cycle exercise. The results demonstrated a clear deterioration in muscle function immediately after fatigue, which was accompanied by a clear reduction in active and passive reflex sensitivity. For active and passive stretch reflexes, this reduction was biphasic (P< 0.05 to P< 0.001). However, for the ratio of the electrically induced maximal Hoffmann reflex to the maximal mass compound action potential, only one significant reduction was seen immediately after fatigue (71.2%,P< 0.01). A similar significant (P< 0.01) decrease in the stretch-resisting force of the muscle was also detected. Clear increases were found in the indirect markers of muscle damage (serum creatine kinese activity and skeletal troponin I), which could imply the occurrence of ultrastructural muscle damage. It is suggested that the acute reduction in reflex sensitivity is of reflex origin and due to two active mechanisms, disfacilitation and presynaptic inhibition. However, the delayed second decline in the sensitivity of some reflex parameters may be attributable to the secondary injury, because of some inflammatory response to the muscle damage. This might emphasize the role of presynaptic inhibition via group III and IV muscle afferents.

Neural, mechanical and muscle factors influence muscle force production. This study was, therefore, designed to compare possible differences in the function of the neuromuscular system among differently adapted subjects. A group of 11 power-trained athletes and 10 endurance-trained athletes volunteered as subjects for this study. Maximal voluntary isometric force and the rate of force production of the knee extensor and the plantar flexor muscles were measured. In addition, basic reflex function was measured in the two experimental conditions. The power athletes produced higher voluntary forces (P<0.01-0.001) with higher rates for force production (P<0.001) by both muscle groups measured. Unexpectedly, however, no differences were noticed in the electromyogram time curves between the groups. During reflex activity, the endurance group demonstrated higher sensitivity to the mechanical stimuli, i.e. the higher reflex amplitude caused a higher rate of reflex force development, and the reflex amplitude correlated with the averaged angular velocity. The differences in the isometric conditions could be explained by obviously different muscle fibre distribution, by different amounts of muscle mass, by possible differences in the force transmission from individual myofibrils to the skeletal muscle and by specificity of training. In addition, differences in nervous system structure and muscle spindle properties could explain the observed differences in reflex activity between the two groups.

Strenuous stretch-shortening cycle exercise was used as a model to study the leakage of proteins from skeletal muscle.