Heikki Kyröläinen's research while affiliated with National Defence University and other places
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Publications (353)
Changes in physiological markers and physical performance in relation to paratroopers’ initial body composition were investigated during a 20-day winter military field training (MFT) and the subsequent 10-day recovery period. Body composition, serum hormone concentrations and enzymatic biomarkers, and physical performance of 58 soldiers were measur...
The changes in steroid hormones are more pronounced in male than female physique athletes during competition preparation
Ville Isola, Juha Hulmi, Eric Helms, Keijo Häkkinen, Heikki Kyröläinen, Juha Ahtiainen
Faculty of Sport and Health Sciences, Neuromuscular Research Center, University of Jyväskylä, Finland; Sports Performance Research Institute...
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 h...
Objectives
Survival training can provide a unique setting for scientific examination of human stress responses and physical performance in a realistic operational military context. The aim of the present study was to observe effects of a 36-h recovery period on serum hormone concentrations, salivary cortisol, and marksmanship during 10-day winter m...
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 XX(X): 000-000, 2023-This study examined the effectiveness of concurrent strength and endurance training with a...
The number of dogs and, with it, dog sports are growing in popularity, and the training of dogs begins at an early age. Although fitness testing is an imperative part of purposeful training and sports, to our knowledge, no objective field tests are available for measuring young dogs’ endurance fitness. The aim of this study is to describe a simple,...
Background:
Low energy availability (LEA) can have negative performance consequences, but the relationships between LEA and performance are poorly understood especially in field conditions. In addition, little is known about the contribution of macronutrients to long-term performance. Therefore, the aim of this study was to evaluate if energy avai...
INTRODUCTION: Fighter pilots must withstand high Gz-forces that can damage the cervical spine. Strength of the cervical musculature is of vital importance when it comes to preventing these G-induced neck injuries. However, there is very little evidence on valid neck muscle strength measurement methods for fighter pilots. The aim of this study was t...
Introduction
Although maximal oxygen uptake (VO 2 max) is generally recognized as the single best indicator of aerobic fitness in youth, interpretation of this parameter and the extent to which it can be improved by training remain controversial, as does the relative importance of VO 2 max for performance in comparison to other factors such as powe...
The 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 meas...
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 uppe...
Severe energy deficit may impair hormonal regulation and physical performance in military trainings. The aim of this study was to examine the associations between energy intake, expenditure, and balance, hormones and military performance during a winter survival training. Two groups were studied: the FEX group (n = 46) had 8-day garrison and field...
Purpose:
The aim of this study was to investigate within-cycle differences in nocturnal heart rate (HR) and heart rate variability (HRV) in naturally menstruating women (NM) and women using combined hormonal contraceptives (CU) or progestin-only hormonal contraceptives (PU).
Methods:
Physically active participants were recruited into three group...
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.
The aim of the present study was to explore th...
This study examined the predictive quality of intervals performed at maximal sustainable effort to predict 3-km and 10-km running times. In addition, changes in interval performance and associated changes in running performance were investigated. Either 6-week (10-km group, n = 29) or 2-week (3-km group, n = 16) interval training periods were perfo...
Purpose: The present study examined the association of vitamin D measured by serum 25(OH)D with physical performance outcomes and serum levels of anabolic hormones in young men.
Methods: 412 young men (age 19 ± 1 year) entering their compulsory military service volunteered to participate in the study. The study consisted of two groups from two diff...
Introduction: This is one of the first intervention studies to examine how low- (LIT) and high-intensity endurance training (HIT) affect durability, defined as ‘time of onset and magnitude of deterioration in physiological-profiling characteristics over time during prolonged exercise’. Methods: Sedentary and recreationally active men (n = 16) and w...
It has been shown that small doses of oral D-glyceric acid (DGA) activate mitochondrial metabolism and reduce inflammation among 50–60-year-old healthy volunteers. The present results with the same small doses reveal that after a 4-day DGA regimen, a dose of DGA activated the HO-1 pathway acutely, while enhanced inflammatory status after the 4-day...
Introduction
The physical and mental training load can be high during military service. Therefore, tailored preconditioning programmes based on assessment of physical fitness could increase readiness for military service, especially among those ones with lower baseline fitness level. The purpose of present study was to investigate how self-assessed...
The aim of this study was to investigate effects of a single infrared sauna (IRS) session on post-exercise recovery of neuromuscular performance, autonomic nervous system function, subjective sleep quality, and muscle soreness. Male basketball players (n = 16) performed two trials consisting of a complex resistance exercise protocol (maximal streng...
Background
There is limited evidence of how physical activity (PA) associates with low back pain (LBP) and neck pain (NP). Particularly, the association between occupational or commuting PA and LBP/NP is unclear. The aim of the present cross-sectional study was to investigate the association between spinal disorders and different physical activity...
Physical activity (PA) has been shown to associate with many health benefits but studies with metabolome-wide associations with PA are still lacking. Metabolome studies may deepen the mechanistic understanding of PA on the metabolic pathways related to health outcomes. The aim of the present study was to study the association of accelerometer based...
Purpose:
To assess the reliability of nocturnal heart rate (HR) and HR variability (HRV) and to analyze the sensitivity of these markers to maximal endurance exercise.
Methods:
Recreational runners recorded nocturnal HR and HRV on nights after 2 identical low-intensity training sessions (n = 15) and on nights before and after a 3000-m running te...
The operation of naval vessels involves watchkeeping 24 h per day, which is globally carried out by a variety of different watch systems. In this study, the rotating 4:4 and fixed 4:4/6:6 two-section watch systems were compared in terms of sleepiness, fatigue, and stress responses. The data collection took place on a Finnish Defence Forces' (FDF) N...
Purpose:
To examine the effects of fatiguing power-loading on neuromuscular properties, force production, and metabolic capacities during four phases of the menstrual cycle (MC); menstruation (M), mid-follicular (mid FOL), ovulation (OV), and mid-luteal (mid LUT).
Methods:
Sixteen eumenorrheic women performed sessions of maximal explosive leg pr...
Healthy lifestyle behaviors including physical activity (PA) have been recognized to contribute positively to mental health. Most of the evidence on relationship between PA and mental health relies on self-reported PA results. Device-based measures on PA or sedentary behavior (SB) are less frequently used in mental health research. The present stud...
The aim of this study was to examine changes in body composition, energy metabolites and electrolytes during a 10-day winter survival training period. Two groups of male soldiers were examined: the REC group ( n = 26; age 19.7 ± 1.2 years; BMI 23.9 ± 2.7) had recovery period between days 6 and 8 in the survival training, whereas the EXC group ( n =...
Purpose
The purpose of this study was to compare heart rate (HR) and heart rate variability in young endurance athletes during nocturnal sleep and in the morning; and to assess whether changes in these values are associated with changes in submaximal running (SRT) and counter-movement jump (CMJ) performance.
Methods
During a three-week period of s...
Heart rate (HR) and heart rate variability (HRV) can be monitored with wearable devices throughout the day. Resting HRV in particular, reflecting cardiac parasympathetic activity, has been proposed to be a useful marker in the monitoring of health and recovery from training. This study examined the validity of the wrist-based photoplethysmography (...
This issue of European Journal of Sport Science includes 8 invited state-of-the-science narrative reviews by well-established researchers in the area 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...
Physical activity is beneficial for improving health and reducing sick leave absences. This article describes a protocol for an intervention using an interactive accelerometer smartphone application, telephone counselling, and physical activity recordings to increase the physical activity of workers in the military and improve their health. Under t...
Purpose: To examine the influence of menstrual cycle (MC) and hormonal contraceptive (HC) cycle phases on physiological variables monitored during incremental treadmill testing in physically active women (eumenorrheic, EUM = 16 and monophasic HC-users, CHC = 12).
Methods: Four running tests to exhaustion were performed at bleeding, mid follicular (...
Background: Based on earlier studies, natural metabolite D-glyceric acid (DGA) does not seem to play any role in whole-body metabolism. Nevertheless, one ethanol oxidation-related rat study with controversial results raised our interest. According to preparatory studies for the regulatory approval of DGA, some highly conserved mechanism seems to su...
The aims of the current study were to examine the relationships between heart rate variability (HRV), salivary cortisol, sleep duration and training in young athletes. Eight athletes (16 ± 1 years) were monitored for 7 weeks during training and competition seasons. Subjects were training for endurance-based winter sports (cross-country skiing and b...
Purpose. this study investigated the effects of two types of training on the bone formation marker of osteocalcin and the bone resorption marker of tartrate-resistant acid phosphatase isoenzyme 5b (trAP5b) in young track and field boys and girls. Methods. the 14-year-old group (10 boys, 10 girls) performed first time an intensive and supervised 8-w...
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 ta...
Sex hormones are suggested to influence energy intake (EI) and metabolic hormones. This study investigated the influence of menstrual cycle (MC) and hormonal contraceptive (HC) cycle phases on EI, energy availability (EA), and metabolic hormones in recreational athletes (eumenorrheic, NHC = 15 and monophasic HC-users, CHC = 9). In addition, 72-h di...
The aim of the study was to examine whether sports participation (SP), engagement in competitive sports (CS), and the type of sport undertaken at the age of 12 are associated with the physical and mental components of health-related quality of life (HRQoL) in young adulthood. The data were collected using questionnaires prior to a compulsory milita...
The purpose of the study was to examine the effects of progressively increased training intensity or volume on the nocturnal heart rate (HR) and heart rate variability (HRV), countermovement jump, perceived recovery, and heart rate-running speed index (HR-RS index). Another aim was to analyze how observed patterns during the training period in thes...
Based on earlier few studies natural metabolite D-glyceric acid does not seem to play any major role in cellular metabolism. Nevertheless, one study that concentrated on ethanol oxidation in the liver increased our curiosity. Therefore, research leading to the present 25 days lasting double blinded human study with placebo control was initiated. Ma...
Limited data are available regarding strength and endurance training adaptations to
occupational physical performance during deployment. This study assessed acute training-induced
changes in neuromuscular (electromyography; EMG) and metabolic (blood lactate, BLa) responses
during a high-intensity military simulation test (MST), performed in the beg...
Background: An adequate level of muscular fitness is related to occupational performance in military personnel, including pilots flying high performance aircraft. The aim of this study was to describe the baseline level and the change in muscular fitness between the first and the second years of the Air Force Academy among fighter pilot cadets. Met...
Purpose:
The aim of this study was to compare the efficacy of three water immersion interventions performed after active recovery compared to active recovery only on the resolution of inflammation and markers of muscle damage post-exercise.
Methods:
Nine physically active men (n = 9; age 20‒35 years) performed an intensive loading protocol, incl...
This study investigated acute responses and post 24-h recovery to four running sessions performed at different intensity zones by supine heart rate variability, countermovement jump, and a submaximal running test. A total of 24 recreationally endurance-trained male subjects performed 90 min low-intensity (LIT), 30 min moderate-intensity (MOD), 6×3...
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 militar...
Purpose: To examine the potential sex differences in adaptations to combined endurance and strength training in recreationally endurance trained (eumenorrheic) women (n = 9) and men (n = 10).
Methods: Isometric (ISOMmax) and dynamic bilateral leg press (1RM), countermovement jump (CMJ), running performance (3,000 m time trial), lean mass and body...
Vigh-Larsen, JF, Haverinen, MT, Panduro, J, Ermidis, G, Andersen, TB, Overgaard, K, Krustrup, P, Parkkari, J, Avela, J, Kyröläinen, H, and Mohr, M. On-ice and office fitness profiles of elite and U20 male ice hockey players of two different national standards. J Strength Cond Res XX(X): 000-000, 2020-Differences in body composition and performance...
Introduction:
Military training programmes are often similar for male and female recruits despite sex differences in physical performance that may influence training adaptations during military service. The present study aimed to compare changes in physical fitness and anthropometrics between Finnish female and male recruits during military servic...
The purpose of the present study was to examine the effects of the contact time on energy cost and lower limb biomechanics during repeated vertical jumping. Nine male Japanese distance runners jumped for three minutes on a force platform for a preferred and long contact time. Sagittal plane kinematics, ground reaction force, and electromyography (E...
Background:
There is growing evidence on positive effects of physical activity (PA) on mental health. However, the focus of previous research on this relationship has typically been on mental health from the perspective of mental health problems rather than from the perspective of mental wellbeing. Further, previous research has commonly focused r...
Background:
Despite numerous studies providing evidence for positive effects of physical activity and physical fitness, evidence for association between physical fitness and health-related quality of life (HRQoL) in young adults is limited. The aim of the present cross-sectional study was to investigate the association of cardiorespiratory and mus...
Microdialysis allows for a preview into local muscle metabolism and can provide physiological insight that blood measurements cannot. Purpose: To examine the potential differential IGF-I system regulation in interstitial fluid during unilateral stretch shortening cycle exercise. Methods: 10 men (26 ± 7 year) performed unilateral jumping [stretch sh...
![Figure 1. Macronutrient intake [E%] of soldiers (N = 35) during a...](publication/341336966/figure/fig1/AS:11431281185557534@1693678467592/Macronutrient-intake-E-of-soldiers-N-35-during-a-6-month-deployment-in-Southern_Q320.jpg)
Objectives:
This observational follow-up study investigated the associations of nutrition and body composition with cardiovascular disease (CVD) risk factors, including pro-inflammatory biomarkers, in soldiers during a 6-month deployment.
Material and methods:
Thirty-five male soldiers were assessed at months 0, 3 and 6, and their parameters, i....
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 po...
Impact statement:
The diagnosis of overtraining syndrome and overreaching poses a great challenge. Military training aims at improving the physical performance of the conscripts, but an excessive training load could also lead to overreaching. This study of Finnish conscripts provides new insights into the pathophysiology of overreaching and overtr...
Wearable electronics are often used for estimating the energy expenditure of the user based on heart rate measurement. While heart rate is a good predictor of calorie consumption at high intensities, it is less precise at low intensity levels, which translates into inaccurate results when estimating daily net energy expenditure. In this study, hear...
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...
New findings:
What is the central question of the study? What are the effects of caffeine on neuromuscular function in a non-fatigued state and during fatiguing exercise? What is the main finding and its importance? In a non-fatigued state caffeine decreased the duration of the silent period evoked by TMS. A caffeine-induced reduction of inhibitor...
Introduction
Active commuting is an inexpensive and accessible form of physical activity and may be beneficial to health. The aim of this study was to investigate the association of active commuting and its subcomponents, cycling and walking, with cardiometabolic risk factors, physical fitness and body composition in young men.
Methods
Participant...
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....
Introduction:
Physical fitness is strongly related to health and may offer valuable information about public health. We investigated trends in physical fitness, leisure-time physical activity (LTPA) and anthropometry of young healthy adult Finnish men in representative population based samples between 2003 and 2015.
Methods:
Three independent cr...
Purpose:
To determine body composition, energy availability, training load, and menstrual status in young elite endurance running athletes (ATH) over 1 year, and in a secondary analysis, to investigate how these factors differ between nonrunning controls (CON), and amenorrheic (AME) and eumenorrheic (EUM) ATH. Correlations to injury, illness, and...
Study aim : The purpose of this study was to compare the effects of cold-water immersion (CWI) vs. active recovery performed after each individual strength and endurance training session over a 10-week period of high-intensity combined strength and endurance training.
Materials and methods : Seventeen healthy men completed 10 weeks of high-intensit...
Introduction
Injuries are the major cause of morbidity and loss of active training days in military populations. Previous investigations have mainly focused on lower extremities. This study evaluated the incidence, diagnosis, and risk factors of upper extremity injuries requiring hospitalization in a large cohort of Finnish conscripts during a 5-ye...
The primary aim of the present study was to identify motivational profiles of Finnish children, and the extent to which profiles could differ from each other in terms of motivational indices. Also, relationships between motivational profiles and organized sports participation were examined. Achievement goal theory framework was used in this study....
Study aim : The purpose of this study was to evaluate neuromuscular adaptations in conscripts with different fitness levels (VO 2max ) during 8 weeks of military basic training (BT).
Material and methods : Twenty-four male conscripts (18–21 years) were divided into two groups (Good Fitness [GF] and Low fitness [LF]) based on their VO 2max at the be...
