Keijo Häkkinen

Keijo Häkkinen
University of Jyväskylä | JYU · Neuromuscular Research Center and Biology of Physical Activity in the Faculty of Sport and Health Sciences

PhD and Professor Emeritus
Keijo Häkkinen works as Professor Emeritus in the fields of Exercise Physiology and especially Science of Sport.

About

842
Publications
360,287
Reads
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35,906
Citations
Introduction
Keijo Häkkinen works currently as professor emeritus at the Neuromuscular Research Center, Biology of Physical Activity in the Faculty of Sport and Health Sciences, University of Jyväskylä: Exercise Physiology, Biomechanics and Science of Sports. The major current projects include Neuromuscular, cardiorespiratory, endocrine and health acute responses and prolonged adaptations to strength and power training and various combined endurance and strength training modes in men and women and athletes.
Additional affiliations
August 1979 - December 2023
University of Jyväskylä
Position
  • Professor Emeritus
Description
  • Bachelor of Science 1975, Master of Science 1977, and Doctor of Philosophy (PhD) 1986 Scientific competence for the academic chair of the professorship in Biomechanics 1991 Scientific competence for the academic chair of the professorship in Exercise Physiology 1992 Scientific competence for the academic chair of the professorship in Science of Sport Coaching and Fitness Testing 2001, Docent 1993 in Biology of Physical Activity, Biology of Physical Training, Medical Faculty, University of Oulu
Education
September 1972 - March 1986
University of Jyväskylä
Field of study
  • Exercise Physiology, Biomechanics, Science of Sport Coaching and Fitness Testing

Publications

Publications (842)
Article
Full-text available
New findings: What is the central question of this study? Do males and females differ in fatiguability during dynamic loadings, and what are the acute neuromuscular and hormonal responses to 20% versus 40% velocity-loss resistance loadings? How does an 8-week velocity-loss resistance training period modify acute neuromuscular and hormonal response...
Article
Kraemer, WJ, Caldwell, LK, Post, EM, Beeler, MK, Emerson, A, Volek, JS, Maresh, CM, Fogt, JS, Fogt, N, Häkkinen, K, Newton, RU, Lopez, P, Sanchez, BN, and Onate, JA. Arousal/stress effects of "Overwatch" eSports game competition in collegiate gamers. J Strength Cond Res XX(X): 000-000, 2022-To date, no physical response data are available for one o...
Article
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This study investigated how two slightly different athlete groups would differ in acute neuromuscular and endocrine responses to specific resistance exercise loadings and recovery compared to untrained participants. Power athletes (PA, n = 8), strength athletes (SA, n = 8) and non-athletes (NA, n = 7) performed power (PL, 7 × 6 × 50% of 1RM), maxim...
Article
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Adults with Down syndrome are an underserved population at high risk for a host of different pathologies from aging and lack of activity. Purpose To examine the effects of a 10-week resistance training program on measures of motor behavior, cognitive function, mood, and physical fitness. Methods Participants ( n = 11) were men and women clinicall...
Article
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Purpose Cancer-induced muscle wasting (i.e., cancer cachexia, CC) is a common and devastating syndrome that results in the death of more than 1 in 5 patients. Although primarily a result of elevated inflammation, there are multiple mechanisms that complement and amplify one another. Research on the use of exercise to manage CC is still limited, whi...
Article
Full-text available
Purpose Men and women typically display different neuromuscular characteristics, force–velocity relationships, and differing strength deficit (upper vs. lower body). Thus, it is not clear how previous recommendations for training with velocity-loss resistance training based on data in men will apply to women. This study examined the inter-sex diffe...
Article
Purpose: The aim of the present investigation was to determine whether a one-hour floatation-REST session could augment recovery from high-intensity resistance exercise (6 x10 back squats, 2 minutes rest) known to induce significant metabolic, adrenergic, and mechanical stress. Methods: Eleven healthy resistance-trained males (age: 22.5 ± 2.3 ye...
Article
Full-text available
Effects of eccentric (ECC) versus concentric (CON) strength training of the upper body performed twice a week for 10 weeks followed by detraining for five weeks on maximal force, muscle activation, muscle mass and serum hormone concentrations were investigated in young women (n = 11 and n = 12). One-repetition bench press (1RM), maximal isometric f...
Article
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Purpose: This study examined the physiological, perceptual, and performance responses to a 2-week block of increased training load and compared whether responses differ between high-intensity interval (HIIT) and low-intensity (LIT) endurance training. Methods: Thirty recreationally trained males and females performed a two-week block of 10 HIIT-se...
Conference Paper
Full-text available
NEUROMUSCULAR COMPARISON OF BENCH PRESS PERFORMANCE AND ACUTE RESPONSES DURING HYPERTROPHIC LOADING IN A TRADITIONAL INDOOR AND A NEW OUTDOOR FITNESS DEVICE Häkkinen, K., Karman, S., Kotikangas, J., Mononen, O., Walker, S., Peltonen, H. Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, 21st Internationa...
Conference Paper
Full-text available
BACK SQUAT ACTION AND ACUTE NEUROMUSCULAR RESPONSES DURING A TYPICAL HYPERTROPHIC LOADING PROTOCOL: COMPARISON BETWEEN A TRADITIONAL INDOOR AND A NEW OUTDOOR FITNESS DEVICE Häkkinen, K., Mononen, O., Walker, S., Kotikangas, J., Karman, S., Peltonen, H. Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, 2...
Article
Räntilä, A, Ahtiainen, JP, Avela, J, Restuccia, J, Kidgell, DJ, and Häkkinen, K. High responders to hypertrophic strength training also tend to lose more muscle mass and strength during detraining than low responders. J Strength Cond Res 35(6): 1500-1511, 2021-This study investigated differences in individual responses to muscle hypertrophy during...
Article
The purpose of this study was to examine the responses of growth hormone (GH) and insulin-like growth factor-I (IGFI) to intense heavy resistance exercise in highly trained men and women to determine what sex-dependent responses may exist. Subjects were highly resistance trained men (N = 8, Mean ± SD; age, yrs., 21 ± 1, height, cm, 175.3 ± 6.7, bod...
Article
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...
Article
The purpose of the present study was to examine the influence of an acute bout of high-intensity resistance exercise on measures of cognitive function. Ten men (Mean ± SD: age = 24.4 ± 3.2 yrs; body mass = 85.7 ± 11.8 kg; height = 1.78 ± 0.08 m; 1 repetition maximum (1RM) = 139.0 ± 24.1 kg) gave informed consent and performed a high-intensity 6 set...
Article
Background Androgen deprivation therapy (ADT) contributes to lean mass loss and adiposity increases in prostate cancer patients. Radiotherapy during ADT might act synergistically and further worsen body composition. Previous investigations have shown that resistance training is an effective method of preserving body composition during ADT, however,...
Preprint
Full-text available
The purpose of the present study was to investigate stress, anabolic and catabolic hormonal levels and their association with interleukin 6 (IL-6) cytokine in patients undergoing lumbar spine fusion (LSF) surgery. Blood samples were collected preoperatively, and at 1, 3, 42 and 90 days postoperatively (POD) from 49 LSF patients with a mean (SD) age...
Article
Full-text available
Abstract Prolonged periods of energy deficit leading to weight loss induce metabolic adaptations resulting in reduced energy expenditure, but the mechanisms for energy conservation are incompletely understood. We examined 42 healthy athletic females (age 27.5 ± 4.0 years, body mass index 23.4 ± 1.7 kg/m2 ) who volunteered into either a group dietin...
Article
Full-text available
This study focused on investigating differences in shooting performance and performance related factors between two different aiming strategies (HOLD, low radial velocity during the approach 0.4‐0.2 seconds before triggering, and TIMING, high radial velocity) in biathlon standing shooting. 23 biathletes fired 8x5 standing shots at rest (REST) and 2...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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Purpose: To analyse the effect of resistance training (RT) performed until volitional failure with low-, moderate- and high-loads on muscle hypertrophy and muscle strength in healthy adults; and assess the possible participant-, design-, and training-related covariates which may affect the adaptations. Methods: Using PRISMA guidelines, MEDLINE, CIN...
Article
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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 consi...
Article
Seppänen, S and Häkkinen, K. Step vs. two-phase gradual volume reduction tapering protocols in strength training: Effects on neuromuscular performance and serum hormone concentrations. J Strength Cond Res XX(X): 000-000, 2020-This study assessed effects of 2 reduced volume tapering protocols on neuromuscular performance and serum hormone concentrat...
Article
Full-text available
Background Sprint performance is an essential skill to target within soccer, which can be likely achieved with a variety of methods, including different on-field training options. One such method could be heavy resisted sprint training. However, the effects of such overload on sprint performance and the related kinetic changes are unknown in a prof...
Article
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...
Article
Full-text available
PurposeThis study examined whether additional external load during the eccentric phase of lower limb strength training exercises led to greater adaptations in knee extensor strength, muscle architecture, and patellar tendon properties than traditional concentric–eccentric training in already-trained men.Methods Twenty-eight men accustomed to streng...
Article
Full-text available
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...
Article
Full-text available
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...
Poster
Full-text available
Purpose. This study focused on investigating differences in shooting performance and performance related factors between two different aiming strategies (HOLD, low approach velocity 0.4-0.2 seconds before triggering, and TIMING, high approach velocity) in biathlon standing shooting. Methods. 23 biathletes fired 8x5 standing shots at rest (REST) an...
Article
We read the article of Buckner et al. (1), hoping to find new insights on resistance training. Unfortunately, the article is a restatement of information contained in previously published reviews from this group. Here are our major concerns: HYPERTROPHY AND STRENGTH GAINS Buckner et al. believe that high-volume phases are unnecessary. Initial alter...
Article
This study aimed to examine the validity of using bar velocity to estimate relative load in squat and bench-press exercises for both young men and women. Twenty-five men and 25 women performed a progressive loading test up to 1-RM in the squat and bench-press exercises, which were repeated after 2-weeks. Relationships between mean propulsive veloci...
Article
This study investigated acute hemodynamic, plasma volume and immunological responses to four loading protocols: sauna only, and sauna after endurance, strength or combined endurance and strength exercise. Twenty-seven healthy, slightly prehypertensive men (age 32.7±6.9 years) were measured at PRE, MID (after exercise), POST, POST30min and POST24h....
Article
Materials and methods: Three months postoperatively, 98 patients were randomized either to the exercise group (EG), with a progressive 12-month home-based exercise program, or to usual care group (UCG), with one guidance session for light home-exercises. Maximal trunk muscle strength was measured by a strain-gauge dynamometer and trunk extensor en...
Article
Full-text available
Resistance training (RT) may improve metabolic health; however, the extent of its effectiveness is constantly evaluated to assess improvements in the group means, thus obscuring the heterogeneous individual effects. This study investigated inter-individual variation in responses to RT as reflected in metabolic health indicators and how age, sex, nu...
Article
Full-text available
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...
Article
The purpose of this study was to examine endurance performance by recording oxygen uptake, heart rate and blood lactate during the obstacle test track, equivalent to competitive performance in female horseback riders. In total 42 female riders participated in the study (show jumping, SJ n = 16, eventing, E n = 26). Age, height and weight of the tot...
Article
Full-text available
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...
Article
Background: The purpose of this study was to investigate effects of strength (S), endurance (E) and concurrent strength and endurance (SE) training on neuromuscular and cardiorespiratory characteristics during the 12-week volume-equated protocols in female horseback riders. Methods: Subjects (N=44) (29.4±8.9 yrs) were assigned to S (n=11), E (n=...
Article
Full-text available
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...
Presentation
Purpose: To investigate hormonal changes and effects of a short recovery period during strenuous winter survival training in Finnish soldiers. Methods: Forty-five (age 20±1 years, height 180±6 cm, body mass 76.6±9.7 kg) male soldiers voluntary participated in the study. Winter SERE (survival, evasion, resistance and escape) training lasted for 10...
Article
Full-text available
New findings: What is the central question of this study? While acute responses of the principal gonadosteroid and corticosteroid hormones to resistance exercise is well documented, there is no information regarding how the key smaller-concentration intermediary hormones respond and potentially influence these hormonal pathways. What is the main f...
Poster
Full-text available
Introduction: Repetition velocity can be used to prescribe the relative load (%1RM) due to its strong relationship (R2=0.98) in the bench press (BP) exercise (1) and in other exercises, (R2=0.96) as in full squat (2). However, one of the main drawbacks of these studies is that, to the best of our knowledge, the load-velocity relationship has been a...
Poster
Full-text available
The aim of the present study is to investigate changes in serum ACTH, cortisol, GH, and IGF-1, SHBG and testosterone concentrations during the acute postoperative trauma and tissue repair process induced by instrumented lumbar spine fusion (LFS). Blood samples were obtained from the patients pre- and postoperatively at the day of surgery, after the...
Preprint
Full-text available
Sprint performance is an essential skill to target within soccer. However, time-consuming intervention models could be easily rejected by coaches. Therefore, alternative and efficient field training options are warranted. One such method could be heavy resisted sprint training. However, it is unknown whether such overload will be efficient in assis...
Article
Rissanen, JA, Häkkinen, A, Laukkanen, J, Kraemer, WJ, and Häkkinen, K. Acute neuromuscular and hormonal responses to different exercise loadings followed by a sauna. J Strength Cond Res XX(X): 000-000, 2019-The purpose of this study was to investigate acute responses of endurance (E + SA), strength (S + SA), and combined endurance and strength exer...
Article
IGF-I and IGFBPs have important physiological modulatory effects and this study sought to examine the influence of active vs. passive recovery following a heavy resistance exercise on IGF-I and IGF binding protein (IGFBP) recovery responses. It was hypothesized that increased IGF-I and decreased inhibitory IGFBPs during active recovery may be refle...
Presentation
INTRODUCTION Modern battlefield requires warfighters to have anaerobic capacity to fulfil the occupational requirements of high intensity movements with heavy load carriage. The purpose of the present study was to compare the effects of different types of physical training on the neuromuscular performance and simulated combat task course performanc...
Article
Background: The purpose of the present study was to examine the levels of endurance and neuromuscular performance variables in female horseback riders. Methods: 52 female Finnish riders were involved (age 29.4±8.9 yrs, height 1.68±0.06 m, weight 67.5±10.0 kg), 19 show-jumping riders (SJ) and 33 eventing riders (E), riding-time minimum of 4 times...
Article
Full-text available
Introduction: Wrist-mounted motion sensors can quantify the volume and intensity of physical activities, but little is known about their long-term validity. Our aim was to validate a wrist motion sensor in estimating daily energy expenditure, including any change induced by long-term participation in endurance and strength training. Supplemental h...
Presentation
Introduction Military survival training (SERE) exposes soldiers to both psychological and physical stress. These stressors have been shown to lead to changes in both hormonal profiles and physical performance (Morgan et al. 2000). The purpose of this study was to investigate changes in daily variation of saliva cortisol (SCOR) concentrations durin...
Conference Paper
Differences Between Responders and Non-responders for Endurance Performance During Combined Training in Military Operation ABSTRACT: 1040 Board #274 May 29 2:00 PM - 3:30 PM Pihlainen, Kai; Santtila, Matti; Häkkinen, Keijo; Kyröläinen, Heikki FACSM Medicine & Science in Sports & Exercise: June 2019 - Volume 51 - Issue 6 - p 276 doi: 10.1249/01.mss....
Article
Full-text available
Exercise and exercise-induced weight loss have a beneficial effect on overall health, including positive effects on molecular pathways associated with immune function, especially in overweight individuals. The main aim of our study was to assess how energy deprivation (i.e., “semi-starvation”) leading to substantial fat mass loss affects the immune...
Article
The aim of the present study was to examine how combined strength and endurance training in the morning and evening influences the adaptations in strength and endurance performance, perception of time management, psychological well-being and sleep. The combined training period lasted for 24 weeks and the participants were divided into the morning t...
Article
Full-text available
The accumulation of fat, especially in visceral sites, is a significant risk factor for several chronic diseases with altered cardiometabolic homeostasis. We studied how intensive long-term weight loss and subsequent weight regain affect physiological changes, by longitudinally interrogating the lipid metabolism and white blood cell transcriptomic...
Article
Full-text available
Purpose:: Interleukin 6 (IL-6) and the acute phase C-reactive protein (CRP) blood concentrations after lumbar spine fusion may be affected by age. The purpose of this prospective observational study was to assess postoperative serum levels of pro-inflammatory IL-6 and CRP after instrumented lumbar spine fusion surgery. We hypothesized that older p...
Article
Full-text available
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...
Poster
Co-authors: Heikki Kyröläinen, Keijo Häkkinen Purpose: To investigate changes in neuromuscular performance, body composition and serum hormone concentrations during military survival training. Methods: Twenty-six (age 20±1 yrs., height 180±7 cm, body mass 76.1±10.4 kg) male soldiers voluntary participated in the study. The SERE course was approxima...