Apostolos Theos

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• M.Sc., Ph.D.
• Deputy Head of Department at Umeå University

Physical exercise may affect drug use by balancing neurohormonal system mechanisms. Cortisol and β-endorphin, associated with stress, mood, and pleasure feelings, can be affected by exercise and act as regulators of withdrawal symptoms associated with drug use during short-term abstinence. The present study investigated the effect of a supervised,...

Introduction Predicting competitive alpine skiing performance using conventional statistical methods has proven challenging. Many studies assessing the relationship between physiological performance and skiing outcomes have employed statistical methods of questionable validity. Furthermore, the reliance on Fédération Internationale de Ski (FIS) poi...

Soccer is a team sport characterized by repeated high-intensity sprints followed by brief periods of recovery. Repeated sprints with (RCOD) and without (RSA) change-of-direction has therefore been recognized as an important fitness component. The purpose of the present study was to examine the differences in physiological responses between RSA and...

Purpose Examine the acute hormonal and cytokine responses to free-weight resistance training in trained prepubertal and pubertal male children. Methods Prepubertal (n = 21; age 11.4 ± 1.1 years; Tanner I–II) and pubertal male children (n = 20; age 15.8 ± 0.7 years; Tanner III–V) conducted a moderate-intensity free-weight resistance training progra...

Physical demands in soccer differ according to league level and playing position and may influence nutritional requirements. This study examined the effect of competition level and playing position on dietary intake in male soccer players (SP). Diet was weighed and recorded by 123 SP for 3 days; before, on the day, and the day after an official mat...

Objectives The objective of the present study was to investigate a) the potential effect of PAP in children’s jumping performance and b) the optimal time frame of the potential PAP effects in the same population Methods Ten healthy male children (age: 12.2 ± 1.2; n= 7, pre-PHV and n= 3, post-PHV) conducted a single set of heavy resistance training...

Sarcopenic obesity (SO) constitutes the coexistence of skeletal muscle mass loss (sarcopenia) and excess adiposity (obesity). It is mainly considered as a condition in the elderly with health-threatening impacts ranging from frailty to mortality. Mitochondrial dysfunction consists one of the basic pathophysiological mechanisms leading to the develo...

To examine the effect of the fluid balance on and performance in young artistic gymnasts during training under ad libitum and prescribed fluid intake conditions, eleven males (12.3 ± 2.6 years, mean ± SD) performed two 3 h identical training sessions. Participants ingested, in a random order, water equivalent to either 50% (LV) or 150% (HV) of thei...

Background No previous systematic review has quantitatively compared the effects of resistance training, endurance training, or concurrent training on hormonal adaptations in children and adolescents. Objective was to examine the effects of exercise training and training type on hormonal adaptations in children and adolescents. Methods A systemati...

Children recover faster than adults in repeated sprints, but it is unclear if their aerobic responses differ. Purpose This study tested the hypothesis that aerobic response (VO2) during repeated sprints is greater in preadolescent boys than in men. Further, this study compared normalization with conventional ratio-scaling and scaling with the use...

Objective: To assess the impact of coronavirus on the physical activity levels before and during self-quarantine, and the effect of self-isolation on the total mood status of Iranian citizens during the covid-19 pandemic. Material and Methods: A national sample of 2359 middle-aged (M age=42.8±5.3 years, n=1183,50.1%, male; n=1148, 48.7% female) Ira...

Purpose: In cross-country (XC) skiing, the ability to use an efficient technique is essential for performance. The study aimed to compare the effects of supplemental static or dynamic core strength training on skiing economy in elite junior XC skiers. Methods: Twenty-four elite junior XC skiers (14 women, 10 men; 17.8 ± 1.1 years; 67.8 ± 10.0 kg, 1...

Resistance exercise has been shown to induce an acute hormonal response. The purpose of this study was to examine upper-body adaptations and the endocrine response to strength training in men and women when subjected to two different types of lower-body resistance training protocols. Nine males and eight females were assigned to either a Heavy Load...

Competitive alpine skiing is a complex sport that requires high physical and technical competence. Testing the physical status of athletes may be important to increase their ability to achieve elite sport-specific performance. This study aimed to investigate the predictive power of the national test battery of the Swedish Olympic Committee (Fysprof...

Eccentric exercise has been extensively used as a model to study the contraction-induced muscle damage and its consequent processes. This study aimed at examining molecular responses associated with tissue remodelling, inflammation and angiogenesis in skeletal muscle during the recovery period after eccentric exercise in humans. Ten healthy men per...

The aim of this study was to investigate the predictive power of aerobic test results and anthropometric variables on FIS-ranking of junior elite alpine skiers. Results from twenty-three male and female adolescent elite alpine skiers from two seasons were included in the multivariate statistical models. Physical work capacity was determined by V̇O2...

The purpose of the present study was to investigate the effect of different training surfaces (hard or sand surface) on agility and passing skills of prepubescent female volleyball players. 45 prepubescent girls (age: 11.1 ± 0.5 years) participated in this study and were separated in three groups. Groups S (N=15) and I (N=15) consisted of volleybal...

Multiple cellular and molecular processes are rapidly activated following skeletal muscle damage to restore normal muscle structure and function. These processes typically involve an inflammatory response and potentially the consequent occurrence of secondary damage before their resolution and the completion of muscle repair or regeneration. The ov...

Gene expression patterns as well as gene interactions are under investigation for their involvement in tumour heterogeneity. The molecular classification of breast cancer based on hormone receptor expression, grade and HER2 receptor levels, is indicative but not adequate enough to complete the prognostic data. The objectives of this study were to v...

Oxygen uptake (VO2) during repeated sprinting differs significantly between different resistive loads in adults. Furthermore in two consecutive Wingate tests children produce energy more aerobically in comparison to adults. PURPOSE: To examine the influence of two different resistive loads on VO2 during repeated sprints and in men and boys. METHODS...

The insulin-like growth factor 1 (IGF1) gene gives rise to multiple transcripts, using an elaborate alternative splicing mechanism. The aim of this study was to shed light on the expression and role of the IGF1 system in human MG-63 osteoblast-like osteosarcoma cells. The expression of the IGF1Ea, IGF1Eb and IGF1Ec isoforms was characterized using...

The purpose of the present study was to examine the impact of training surface in agility of prepubescent volleyball players. Thirty female prepubescent volleyball players (age: 11.2 ± 0.6yrs) took part in this study and were randomly allocated in two groups. Group A (N=15) participated in a 10 week training programme in sand surface, while group B...

This study compared the effects of two different half-squat training programs on the repeated-sprint ability of soccer players during the preseason. Twenty male professional soccer players were divided into 2 groups: One group (S-group) performed 4 sets of 5 repetitions with 90% of their 1-repetition maximum (1RM), and the other group (H-group) per...

This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction...

OBJECTIVE: Recent studies, have shown a strong relationship between maximal half-squat strength and movement velocity (Wisloff et al, 2004) and suggested that training using heavy weights (>85% 1 RM) may be preferable for soccer players (Hoff and Helgerud, 2002). However, no study has compared this type of training with a program using lower loads...