Hormetic modulation of angiogenic factors by exercise-induced mechanical and metabolic stress in human skeletal muscle

This study used an integrative experimental model in humans to investigate whether muscle angiogenic factors are differentially modulated by exercise stimuli eliciting different degrees of mechanical and metabolic stress. In a randomized crossover design, 12 men performed two low-volume high-intensity exercise regimens, including short sprint intervals (SSI) or long sprint intervals (LSI) inducing pronounced mechanical/metabolic stress, and a high-volume moderate-intensity continuous exercise protocol (MIC) inducing mild but prolonged mechanical/metabolic stress. Gene and protein expression of angiogenic factors was determined in vastus lateralis muscle samples obtained before and after exercise. Exercise upregulated muscle VEGF mRNA to a greater extent in LSI and MIC compared with SSI. Analysis of angiogenic factors sensitive to shear stress revealed more marked exercise-induced VEGF receptor 2 (VEGF-R2) mRNA responses in MIC than SSI, as well as greater platelet endothelial cell adhesion molecule (PECAM-1) and endothelial nitric oxide synthase (eNOS) mRNA responses in LSI than SSI. No apparent exercise-induced phosphorylation of shear stress-sensory proteins VEGF-R2^Tyr1175, PECAM-1^Tyr713, and eNOS^Ser1177 was observed despite robust elevations in femoral artery shear stress. Exercise evoked greater mRNA responses of the mechanical stretch sensor matrix metalloproteinase-9 (MMP9) in SSI than MIC. Exercise-induced mRNA responses of the metabolic stress sensor hypoxia-inducible factor-1α (HIF-1α) were more profound in LSI than SSI. These results suggest that low-volume high-intensity exercise transcriptionally activates angiogenic factors in a mechanical/metabolic stress-dependent manner. Furthermore, the angiogenic potency of low-volume high-intensity exercise appears similar to that of high-volume moderate-intensity exercise, but only on condition of eliciting severe mechanical/metabolic stress. We conclude that the angiogenic stimulus produced by exercise depends on both magnitude and protraction of myocellular homeostatic perturbations.NEW & NOTEWORTHY Skeletal muscle capillary growth is orchestrated by angiogenic factors sensitive to mechanical and metabolic signals. In this study, we employed an integrative exercise model to synergistically target, yet to different extents and for different durations, the mechanical and metabolic components of muscle activity that promote angiogenesis. Our results suggest that the magnitude of the myocellular perturbations incurred during exercise determines the amplitude of the angiogenic molecular signals, implying hormetic modulation of skeletal muscle angiogenesis by exercise-induced mechanical and metabolic stress.

Inactivity and exercise training differentially regulate abundance of Na+-K+-ATPase in human skeletal muscle

Physical inactivity is a global health risk that can be addressed through application of exercise training suitable for an individual's health and age. People's willingness to participate in physical activity is often limited by an initially poor physical capability and early onset of fatigue. One factor associated with muscle fatigue during intense contractions is an inexcitability of skeletal muscle cells, reflecting impaired transmembrane Na⁺/K⁺ exchange and membrane depolarization, which are regulated via the transmembranous protein Na⁺-K⁺-ATPase (NKA). This short review focuses on the plasticity of NKA in skeletal muscle in humans after periods of altered usage, exploring NKA upregulation with exercise training and downregulation with physical inactivity. In human skeletal muscle, the NKA content quantified by [³H]ouabain binding site content shows robust, yet tightly constrained, upregulation of 8-22% with physical training, across a broad range of exercise training types. Muscle NKA content in humans undergoes extensive downregulation with injury that involves substantial muscular inactivity. Surprisingly, however, no reduction in NKA content was found in the single study that investigated short-term disuse. Despite clear findings that exercise training and injury modulate NKA content, the adaptability of the individual NKA isoforms in muscle (α_1-3 and β_1-3) and of the accessory and regulatory protein FXYD1 are surprisingly inconsistent across studies, for exercise training as well as for injury/disuse. Potential reasons for this are explored. Finally, we provide suggestions for future studies to provide greater understanding of NKA regulation during exercise training and inactivity in humans.

Metabolic stress-dependent regulation of the mitochondrial biogenic molecular response to high-intensity exercise in human skeletal muscle

KEY POINTS

Low-volume high-intensity exercise training promotes muscle mitochondrial adaptations that resemble those associated with high-volume moderate-intensity exercise training. These training-induced mitochondrial adaptations stem from the cumulative effects of transient transcriptional responses to each acute exercise bout. However, whether metabolic stress is a key mediator of the acute molecular responses to high-intensity exercise is still incompletely understood. Here we show that, by comparing different work-matched low-volume high-intensity exercise protocols, more marked metabolic perturbations were associated with enhanced mitochondrial biogenesis-related muscle mRNA responses. Furthermore, when compared with high-volume moderate-intensity exercise, only the low-volume high-intensity exercise eliciting severe metabolic stress compensated for reduced exercise volume in the induction of mitochondrial biogenic mRNA responses. The present results, besides improving our understanding of the mechanisms mediating exercise-induced mitochondrial biogenesis, may have implications for applied and clinical research that adopts exercise as a means to increase muscle mitochondrial content and function in healthy or diseased individuals.

ABSTRACT

The aim of the present study was to examine the impact of exercise-induced metabolic stress on regulation of the molecular responses promoting skeletal muscle mitochondrial biogenesis. Twelve endurance-trained men performed three cycling exercise protocols characterized by different metabolic profiles in a randomized, counter-balanced order. Specifically, two work-matched low-volume supramaximal-intensity intermittent regimes, consisting of repeated-sprint (RS) and speed endurance (SE) exercise, were employed and compared with a high-volume continuous moderate-intensity exercise (CM) protocol. Vastus lateralis muscle samples were obtained before, immediately after, and 3 h after exercise. SE produced the most marked metabolic perturbations as evidenced by the greatest changes in muscle lactate and pH, concomitantly with higher post-exercise plasma adrenaline levels in comparison with RS and CM. Exercise-induced phosphorylation of CaMKII and p38 MAPK was greater in SE than in RS and CM. The exercise-induced PGC-1α mRNA response was higher in SE and CM than in RS, with no difference between SE and CM. Muscle NRF-2, TFAM, MFN2, DRP1 and SOD2 mRNA content was elevated to the same extent by SE and CM, while RS had no effect on these mRNAs. The exercise-induced HSP72 mRNA response was larger in SE than in RS and CM. Thus, the present results suggest that, for a given exercise volume, the initial events associated with mitochondrial biogenesis are modulated by metabolic stress. In addition, high-intensity exercise seems to compensate for reduced exercise volume in the induction of mitochondrial biogenic molecular responses only when the intense exercise elicits marked metabolic perturbations.

Hypertrophic effect of inhaled beta2 -agonist with and without concurrent exercise training: A randomized controlled trial

Due to a high prevalence of asthma and exercise-induced bronchoconstriction in elite athletes, there is a high use of beta₂ -adrenoceptor agonists (beta₂ -agonists) in the athletic population. While anabolic in rodents, no study has been able to detect hypertrophy in humans after chronic beta₂ -agonist inhalation. We investigated whether inhaled beta₂ -agonist, terbutaline, alters body composition and metabolic rate with and without concurrent exercise training in healthy young men. Sixty-seven participants completed a 4-week intervention of daily terbutaline (8 × 0.5 mg) or placebo treatment without concurrent training (habitual; n = 23), with resistance (n = 23) or endurance (n = 21) training 3 times weekly. Before and after the interventions, participant's body composition was determined by dual-energy X-ray absorptiometry and resting metabolic rate and substrate oxidation by indirect calorimetry. Terbutaline increased lean body mass by 1.03 kg (95% CI 0.29-1.76; P < .05) and 1.04 kg (95% CI 0.16-1.93; P < .05) compared to placebo in the habitual and resistance training group, respectively, but had no effect compared to placebo in the endurance training group [-0.56 kg (95% CI -1.74-0.62; P > .05)]. Fat mass, bone mineral content, and resting metabolic rate did not change differently between treatments with the intervention. Daily inhalation of terbutaline in near-therapeutic doses induces skeletal muscle growth. This observation should be a concern for antidoping authorities.

Increased FXYD1 and PGC-1α mRNA after blood flow-restricted running is related to fibre type-specific AMPK signalling and oxidative stress in human muscle

Aim

This study explored the effects of blood flow restriction (BFR) on mRNA responses of PGC‐1α (total, 1α1, and 1α4) and Na⁺,K⁺‐ATPase isoforms (NKA; α_1‐3, β_1‐3, and FXYD1) to an interval running session and determined whether these effects were related to increased oxidative stress, hypoxia, and fibre type‐specific AMPK and CaMKII signalling, in human skeletal muscle.

Methods

In a randomized, crossover fashion, 8 healthy men (26 ± 5 year and 57.4 ± 6.3 mL kg⁻¹ min⁻¹) completed 3 exercise sessions: without (CON) or with blood flow restriction (BFR), or in systemic hypoxia (HYP, ~3250 m). A muscle sample was collected before (Pre) and after exercise (+0 hour, +3 hours) to quantify mRNA, indicators of oxidative stress (HSP27 protein in type I and II fibres, and catalase and HSP70 mRNA), metabolites, and α‐AMPK Thr¹⁷²/α‐AMPK, ACC Ser²²¹/ACC, CaMKII Thr²⁸⁷/CaMKII, and PLBSer¹⁶/PLB ratios in type I and II fibres.

Results

Muscle hypoxia (assessed by near‐infrared spectroscopy) was matched between BFR and HYP, which was higher than CON (~90% vs ~70%; P < .05). The mRNA levels of FXYD1 and PGC‐1α isoforms (1α1 and 1α4) increased in BFR only (P < .05) and were associated with increases in indicators of oxidative stress and type I fibre ACC Ser²²¹/ACC ratio, but dissociated from muscle hypoxia, lactate, and CaMKII signalling.

Conclusion

Blood flow restriction augmented exercise‐induced increases in muscle FXYD1 and PGC‐1α mRNA in men. This effect was related to increased oxidative stress and fibre type‐dependent AMPK signalling, but unrelated to the severity of muscle hypoxia, lactate accumulation, and modulation of fibre type‐specific CaMKII signalling.

Feasibility of high-intensity training in asthma

Background: High-intensity interval training is an effective and popular training regime but its feasibility in untrained adults with asthma is insufficiently described.

Objective: The randomized controlled trial ‘EFFORT Asthma’ explored the effects of behavioural interventions including high-intensity interval training on clinical outcomes in nonobese sedentary adults with asthma. In this article we present a sub analysis of data aiming to evaluate if patients’ pre-intervention levels of asthma control, FEV1, airway inflammation and airway hyperresponsiveness (AHR) predicted their training response to the high-intensity interval training program, measured as increase in maximal oxygen consumption (VO₂max).

Design: We used data from the EFFORT Asthma Study. Of the 36 patients randomized to the 8-week exercise intervention consisting of high-intensity training three times per week, 29 patients (45% females) completed the study and were included in this data analysis. Pre-intervention assessment included the asthma control questionnaire (ACQ), spirometry, fractional exhaled nitric oxide (FeNO) and AHR to mannitol. VO₂ max was measured during an incremental cycle test.

Results: The majority of included patients had partly or uncontrolled asthma reflected by a mean (SD) ACQ at 1.7 (0.6). Median (IQR) FeNO was 28.5 (23.8) ppb and 75% had a positive mannitol test indicating AHR.

The association between patients’ training response measured as increase in VO₂max and pre-intervention ACQ scores was not statistically significant (p = 0.49). Likewise, the association between patients’ increase in VO₂max and FeNO as well as AHR was not statistically significant (p = 0.80 and p = 0.58).

Conclusions: Included asthma patients could adhere to the high-intensity interval protocol and improve their VO₂max regardless of pre-intervention levels of asthma control, airway inflammation and AHR.

Effect of team sports and resistance training on physical function, quality of life, and motivation in older adults

The aim of this study was to investigate the effect of team sports and resistance training on physical function, psychological health, quality of life, and motivation in older untrained adults. Twenty-five untrained men and forty-seven untrained women aged 80 (range: 67-93) years were recruited. Fifty-one were assigned to a training group (TRG) of which twenty-five performed team training (TG) and twenty-six resistance training (RG). The remaining twenty-one were allocated to a control group (CG). TRG trained for 1 hour twice a week for 12 weeks. Compared with CG, TRG improved the number of arm curls within 30 seconds (P<.05) and 30-seconds chair stand (P<.05) during the intervention. In TRG, participation in training led to higher (P<.05) scores in the subscales psychological well-being, general quality of life, and health-related quality of life, as well as decreased anxiety and depression levels. No differences between changes in TG and RG were found over the intervention period, neither in physical function tests nor psychological questionnaires. Both TG and RG were highly motivated for training, but TG expressed a higher degree of enjoyment and intrinsic motivation mainly due to social interaction during the activity, whereas RG was more motivated by extrinsic factors like health and fitness benefits. In conclusion, both team training and resistance training improved physical function, psychological well-being, and quality of life. However, team sport training motivated the participants more by intrinsic factors than resistance training.

Performance in sports--With specific emphasis on the effect of intensified training

Performance in most sports is determined by the athlete's technical, tactical, physiological and psychological/social characteristics. In the present article, the physical aspect will be evaluated with a focus on what limits performance, and how training can be conducted to improve performance. Specifically how intensified training, i.e., increasing the amount of aerobic high-intensity and speed endurance training, affects physiological adaptations and performance of trained subjects. Periods of speed endurance training do improve performance in events lasting 30 s-4 min, and when combined with aerobic high-intensity sessions, also performance during longer events. Athletes in team sports involving intense exercise actions and endurance aspects, such as soccer and basketball, can also benefit from intensified training. Speed endurance training does reduce energy expenditure and increase expression of muscle Na(+), K(+) pump α subunits, which may preserve muscle cell excitability and delay fatigue development during intense exercise. When various types of training are conducted in the same period (concurrent training), as done in a number of sports, one type of training may blunt the effect of other types of training. It is not, however, clear how various training modalities are affecting each other, and this issue should be addressed in future studies.

Effect of floorball training on blood lipids, body composition, muscle strength, and functional capacity of elderly men

Floorball training consists of intense repeated exercise and may offer a motivating and social stimulating team activity in elderly individuals. However, the effect of floorball training in elderly adults on physiological adaptations important for health is not known. Thus, this study examined the effect of floorball training on blood lipids, muscle strength, body composition, and functional capacity of men aged 65-76 years. Thirty-nine recreational active men were randomized into a floorball group (FG; n = 22) or petanque group (PG; n = 17), in which training was performed 1 h twice a week for 12 weeks. In FG and PG, average heart rate (HR) during training was 80% and 57%, respectively, of maximal HR. In FG, plasma low-density lipoprotein (LDL) cholesterol and triglycerides were 11% and 8% lower (P < 0.05), respectively. Insulin resistance determined by homeostatic model assessment (HOMA-IR) was reduced (P < 0.05) by 18%. HR during submaximal cycling was 5% lower (P < 0.05), and maximal voluntary contraction force was 8% higher (P < 0.05). Total and visceral fat content was lowered (P < 0.05) by 5% and 14%, respectively, HR at rest was 8% lower (P < 0.05) and performance in four different functional capacity tests were better (P < 0.05) after compared to before the training period. No changes were observed in PG. In conclusion, 12 weeks of floorball training resulted in a number of favorable effects important for health and functional capacity, suggesting that floorball training can be used as a health-promoting activity in elderly men.

Effects of long-term football training on the expression profile of genes involved in muscle oxidative metabolism

We investigated whether long-term recreational football training affects the expression of health-related biochemical and molecular markers in healthy untrained subjects. Five untrained healthy men trained for 1 h 2.4 times/week for 12 weeks and 1.3 times/week for another 52 weeks. Blood samples and a muscle biopsy from the vastus lateralis were collected at T0 (pre intervention) and at T1 (post intervention). Gene expression was measured by RTqPCR on RNA extracted from muscle biopsies. The expression levels of the genes principally involved in energy metabolism (PPARγ, adiponectin, AMPKα1/α2, TFAM, NAMPT, PGC1α and SIRT1) were measured at T0 and T1. Up-regulation of PPARγ (p < 0.0005), AMPKα1 (p < 0.01), AMPKα2 (p < 0.0005) and adiponectin was observed at T1 vs T0. Increases were also found in the expression of TFAM (p < 0.001), NAMPT (p < 0.01), PGC1α (p < 0.01) and SIRT1 (p < 0.01), which are directly or indirectly involved in the glucose and lipid oxidative metabolism. Multiple linear regression analysis revealed that fat percentage was independently associated with NAMPT, PPARγ and adiponectin expression. In conclusion, long-term recreational football training could be a useful tool to improve the expression of muscle molecular biomarkers that are correlated to oxidative metabolism in healthy males.

β2-adrenergic stimulation enhances Ca2+ release and contractile properties of skeletal muscles, and counteracts exercise-induced reductions in Na+-K+-ATPase Vmax in trained men

The aim of the present study was to examine the effect of β2-adrenergic stimulation on skeletal muscle contractile properties, sarcoplasmic reticulum (SR) rates of Ca(2+) release and uptake, and Na(+)-K(+)-ATPase activity before and after fatiguing exercise in trained men. The study consisted of two experiments (EXP1, n = 10 males, EXP2, n = 20 males), where β2-adrenoceptor agonist (terbutaline) or placebo was randomly administered in double-blinded crossover designs. In EXP1, maximal voluntary isometric contraction (MVC) of m. quadriceps was measured, followed by exercise to fatigue at 120% of maximal oxygen uptake (V̇O2, max ). A muscle biopsy was taken after MVC (non-fatigue) and at time of fatigue. In EXP2, contractile properties of m. quadriceps were measured with electrical stimulations before (non-fatigue) and after two fatiguing 45 s sprints. Non-fatigued MVCs were 6 ± 3 and 6 ± 2% higher (P < 0.05) with terbutaline than placebo in EXP1 and EXP2, respectively. Furthermore, peak twitch force was 11 ± 7% higher (P < 0.01) with terbutaline than placebo at non-fatigue. After sprints, MVC declined (P < 0.05) to the same levels with terbutaline as placebo, whereas peak twitch force was lower (P < 0.05) and half-relaxation time was prolonged (P < 0.05) with terbutaline. Rates of SR Ca(2+) release and uptake at 400 nm [Ca(2+)] were 15 ± 5 and 14 ± 5% (P < 0.05) higher, respectively, with terbutaline than placebo at non-fatigue, but declined (P < 0.05) to similar levels at time of fatigue. Na(+)-K(+)-ATPase activity was unaffected by terbutaline compared with placebo at non-fatigue, but terbutaline counteracted exercise-induced reductions in maximum rate of activity (Vmax) at time of fatigue. In conclusion, increased contractile force induced by β2-adrenergic stimulation is associated with enhanced rate of Ca(2+) release in humans. While β2-adrenergic stimulation elicits positive inotropic and lusitropic effects on non-fatigued m. quadriceps, these effects are blunted when muscles fatigue.

Effects of acute and 2-week administration of oral salbutamol on exercise performance and muscle strength in athletes

Our objective was to investigate effects of acute and 2-week administration of oral salbutamol on repeated sprint ability, exercise performance, and muscle strength in elite endurance athletes. Twenty male elite athletes [VO2max: 69.4 ± 1.8 (Mean ± SE) mL/min/kg], aged 25.9 ± 1.4 years, were included in a randomized, double-blinded and placebo-controlled parallel study. At baseline, after acute administration, and again after 2-week administration of the study drugs (8 mg salbutamol or placebo), subjects' maximal voluntary contraction (MVC) of m. quadriceps and isometric endurance of m. deltoideus were measured, followed by three repeated Wingate tests. Exercise performance at 110% of VO2max was determined on a bike ergometer. Acute administration of salbutamol increased peak power during first Wingate test by 4.1 ± 1.7% (P < 0.05). Two-week administration of salbutamol increased (P < 0.05) peak power during first and second Wingate test by 6.4 ± 2.0 and 4.2 ± 1.0%. Neither acute nor 2-week administration of salbutamol had any effect on MVC, exercise performance at 110% of VO2max or on isometric endurance. No differences were observed in the placebo group. In conclusion, salbutamol benefits athletes' sprint ability. Thus, the present study supports the restriction of oral salbutamol in competitive sports.

Effect of football or strength training on functional ability and physical performance in untrained old men

The effects of 16 weeks of football or strength training on performance and functional ability were investigated in 26 (68.2 ± 3.2 years) untrained men randomized into a football (FG; n = 9), a strength training (ST; n = 9), or a control group (CO; n = 8). FG and ST trained 1.6 ± 0.1 and 1.5 ± 0.1 times per week, respectively, with higher (P < 0.05) average heart rate (HR) (∼140 vs 100 bpm) and time >90%HRmax (17 vs 0%) in FG than ST, and lower (P < 0.05) peak blood lactate in FG than ST (7.2 ± 0.9 vs 10.5 ± 0.6 mmol/L). After the intervention period (IP), VO₂ max (15%; P < 0.001), cycle time to exhaustion (7%; P < 0.05), and Yo-Yo Intermittent Endurance Level 1 performance (43%; P < 0.01) were improved in FG, but unchanged in ST and CO. HR during walking was 12% and 10% lower (P < 0.05) in FG and ST, respectively, after IP. After IP, HR and blood lactate during jogging were 7% (P < 0.05) and 30% lower (P < 0.001) in FG, but unchanged in ST and CO. Sit-to-stand performance was improved (P < 0.01) by 29% in FG and 26% in ST, but not in CO. In conclusion, football and strength training for old men improves functional ability and physiological response to submaximal exercise, while football additionally elevates maximal aerobic fitness and exhaustive exercise performance.

Structural and functional cardiac adaptations to 6 months of football training in untrained hypertensive men

We investigated the effects of 3 and 6 months of regular football training on cardiac structure and function in hypertensive men. Thirty-one untrained males with mild-to-moderate hypertension were randomized 2:1 to a football training group (n = 20) and a control group receiving traditional recommendations on healthy lifestyle (n = 11). Cardiac measures were evaluated by echocardiography. The football group exhibited significant (P < 0.05) changes in cardiac dimensions and function after just 3 months: Left ventricular (LV) end-diastolic volume increased from 104 ± 25 to 117 ± 29 mL. LV diastolic function improved measured as E/A ratio (1.15 ± 0.32 to 1.54 ± 0.38), early diastolic velocity, E' (11.0 ± 2.5 to 11.9 ± 2.6 cm/s), and isovolumetric relaxation time (74 ± 13 to 62 ± 13 ms). LV systolic function improved measured as longitudinal displacement (10.7 ± 2.1 to 12.1 ± 2.3 mm). Right ventricular function improved with respect to tricuspid annular plane systolic excursion (21.8 ± 3.2 to 24.5 ± 3.7 mm). Arterial blood pressure decreased in both groups, but significantly more in the football training group. No significant changes were observed in the control group. In conclusion, short-term football training improves LV diastolic function in untrained men with mild-to-moderate arterial hypertension. Furthermore, it may improve longitudinal systolic function of both ventricles. The results suggest that football training has favorable effects on cardiac function in hypertensive men.

Cardiovascular adaptations to 4 and 12 months of football or strength training in 65- to 75-year-old untrained men

The study examined the effects of 1 year of football or strength training on cardiovascular function in 65- to 75-year-old men. Twenty-six untrained men (age: 68.2 ± 3.2 years) were randomized to football training (FTG; n = 9), strength training (STG; n = 9), or control (CG; n = 8). In FTG, left ventricular (LV) internal diastolic diameter, end-diastolic volume, and mass index were 8%, 21%, and 18% higher (P < 0.01), respectively, after 12 months, with no changes in STG and CG. After 12 months, LV ejection fraction was increased (P < 0.05) by 8% and 5% in FTG and STG, respectively, and systolic longitudinal two-dimensional strain by 8% and 6%, whereas right ventricular systolic function improved (P < 0.05) by 22% in FTG, but not in STG and CG. In FTG, LV diastolic mitral inflow (E/A) ratio and peak early diastolic velocity (E') improved (P < 0.05) by 25% and 12%, respectively, after 12 months, with no changes in STG and CG. In FTG, maximum oxygen uptake was 16% and 18% higher (P < 0.001) after 4 and 12 months, respectively, and resting heart rate was 6 and 8 beats per minute lower (P < 0.001), respectively, with no changes in STG and CG. In conclusion, football training elicited superior cardiovascular effects compared with strength training in elderly untrained men.

A preliminary study: effects of football training on glucose control, body composition, and performance in men with type 2 diabetes

The effects of regular football training on glycemic control, body composition, and peak oxygen uptake (VO₂ peak) were investigated in men with type 2 diabetes mellitus (T2DM). Twenty-one middle-aged men (49.8 ± 1.7 years ± SEM) with T2DM were divided into a football training group (FG; n = 12) and an inactive control group (CG; n = 9) during a 24-week intervention period (IP). During a 1-h football training session, the distance covered was 4.7 ± 0.2 km, mean heart rate (HR) was 83 ± 2% of HRmax, and blood lactate levels increased (P < 0.001) from 2.1 ± 0.3 to 8.2 ± 1.3 mmol/L. In FG, VO₂ peak was 11% higher (P < 0.01), and total fat mass and android fat mass were 1.7 kg and 12.8% lower (P < 0.001), respectively, after IP. After IP, the reduction in plasma glucose was greater (P = 0.02) in FG than the increase in CG, and in FG, GLUT-4 tended to be higher (P = 0.072) after IP. For glycosylated hemoglobin (HbA1), an overall time effect (P < 0.01) was detected after 24 weeks. After IP, the number of capillaries around type I fibers was 7% higher (P < 0.05) in FG and 5% lower (P < 0.05) in CG. Thus, in men with T2DM, regular football training improves VO₂ peak, reduces fat mass, and may positively influence glycemic control.

Cardiovascular function is better in veteran football players than age-matched untrained elderly healthy men

The aim of the study was to determine whether lifelong football training may improve cardiovascular function, physical fitness, and body composition. Our subjects were 17 male veteran football players (VPG; 68.1 ± 2.1 years) and 26 healthy age-matched untrained men who served as a control group (CG; 68.2 ± 3.2 years). Examinations included measurements of cardiac function, microvascular endothelial function [reactive hyperemic index (RHI)], maximum oxygen uptake (VO2max), and body composition. In VPG, left ventricular (LV) end-diastolic volume was 20% larger (P < 0.01) and LV ejection fraction was higher (P < 0.001). Tissue Doppler imaging revealed an augmented LV longitudinal displacement, i.e., LV shortening of 21% (P < 0.001) and longitudinal 2D strain was 12% higher (P < 0.05), in VPG. In VPG, resting heart rate was lower (6 bpm, P < 0.05), and VO2max was higher (18%, P < 0.05). In addition, RHI was 21% higher (P < 0.05) in VPG. VPG also had lower body mass index (P < 0.05), body fat percentage, total body fat mass, android fat percentage, and gynoid fat percentage (all P < 0.01). Lifelong participation in football training is associated with better LV systolic function, physical fitness, microvascular function, and a healthier body composition. Overall, VPG have better cardiovascular function compared with CG, which may reduce their cardiovascular morbidity and mortality.

Angiogenic response to passive movement and active exercise in individuals with peripheral arterial disease

Peripheral arterial disease (PAD) is caused by atherosclerosis and is associated with microcirculatory impairments in skeletal muscle. The present study evaluated the angiogenic response to exercise and passive movement in skeletal muscle of PAD patients compared with healthy control subjects. Twenty-one PAD patients and 17 aged control subjects were randomly assigned to either a passive movement or an active exercise study. Interstitial fluid microdialysate and tissue samples were obtained from the thigh skeletal muscle. Muscle dialysate vascular endothelial growth factor (VEGF) levels were modestly increased in response to either passive movement or active exercise in both subject groups. The basal muscle dialysate level of the angiostatic factor thrombospondin-1 protein was markedly higher (P < 0.05) in PAD patients compared with the control subjects, whereas soluble VEGF receptor-1 dialysate levels were similar in the two groups. The basal VEGF protein content in the muscle tissue samples was ∼27% lower (P < 0.05) in the PAD patients compared with the control subjects. Analysis of mRNA expression for a range of angiogenic and angiostatic factors revealed a modest change with active exercise and passive movement in both groups, except for an increase (P < 0.05) in the ratio of angiopoietin-2 to angiopoietin-1 mRNA in the PAD group with both interventions. PAD patients and aged individuals showed a similar limited angiogenic response to active exercise and passive movement. The limited increase in muscle extracellular VEGF combined with an elevated basal level of thrombospondin-1 in muscle extracellular fluid of PAD patients may restrict capillary growth in these patients.

Combined inhalation of beta2 -agonists improves swim ergometer sprint performance but not high-intensity swim performance

There is a high prevalence of asthma and airway hyperresponsiveness (AHR) in elite athletes, which leads to a major use of beta2 -agonists. In a randomized double-blinded crossover study, we investigated the effects of combined inhalation of beta2 -agonists (salbutamol, formoterol, and salmeterol), in permitted doses within the World Anti-Doping Agency 2013 prohibited list, in elite swimmers with (AHR, n = 13) or without (non-AHR, n = 17) AHR. Maximal voluntary isometric contraction of m. quadriceps (MVC), sprint performance on a swim ergometer and performance in an exhaustive swim test at 110% of VO2max were determined. Venous plasma interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured post-exercise. No improvement was observed in the exhaustive swim test, but swim ergometer sprint time was improved (P < 0.05) in both groups from 57 ± 1.7 to 56 ± 1.8 s in AHR and 58.3 ± 1 to 57.4 ± 1 s in non-AHR. MVC and post-exercise plasma IL-6 increased (P < 0.05) with beta2 -agonists in both groups, whereas IL-8 only increased in AHR. In summary, inhalation of beta2 -agonists, in permitted doses, did not improve swim performance in elite swimmers. However, swim ergometer sprint performance and MVC were increased, which should be considered when making future anti-doping regulations.

Anthropometric characteristics, physical fitness and technical performance of under-19 soccer players by competitive level and field position

Anthropometric characteristics, physical fitness and technical skills of under-19 (U19) soccer players were compared by competitive level (elite, n=95; non-elite, n=85) and playing position (goalkeeper, central defender, fullback, midfield, forward). Fitness tests included 5- and 30-m sprints, agility, squat jump (SJ) and countermovement jump (CMJ), strength and Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2). Soccer-specific skills included ball control and dribbling. Independent of position, elite players presented more hours of training per year than non-elite players (d>1.2). Stature and body mass discriminated elite from non-elite players among goalkeepers and central defenders (d>0.6). Major differences were noted between elite and non-elite goalkeepers for SJ, CMJ, Yo-Yo IE2, and ball control (d>1.2). Elite central defenders performed better than their non-elite counterparts in SJ and ball control tests (d>1.2). Elite players presented better agility and Yo-Yo IE2 performances than non-elite players within all positional roles (d>0.6). In conclusion, U19 players differed in anthropometric characteristics, physical fitness and technical skills by competitive level within field positions.

Influence of nitrate supplementation on VO₂ kinetics and endurance of elite cyclists

The present study examined if an elevated nitrate intake would improve VO(2) kinetics, endurance, and repeated sprint capacity in elite endurance athletes. Ten highly trained cyclists (72 ± 4 mL O(2) /kg/min, mean ± standard deviation) underwent testing for VO(2) kinetics (3 × 6 min at 298 ± 28 W), endurance (120 min preload followed by a 400-kcal time trial), and repeated sprint capacity (6 × 20 s sprints, recovery 100 s) during two 6-day periods in randomized order with a daily ingestion of either 0.5 L beetroot (BR) juice to increase nitrate levels or a 0.5 L placebo (PLA) drink with blackcurrant juice. Plasma NOx (nitrate + nitrite) levels were higher (P < 0.01) in BR (147 ± 102 and 159 ± 103 μM after 4 and 6 days of beverage intake, respectively) compared with PLA (41 ± 10 and 40 ± 7 μM). VO(2) kinetics and exercise economy were the same in BR and PLA. Time-trial performance was similar with an average completion time of 18:20 and 18:37 min:s in BR and PLA, respectively, with average power outputs of 290 ± 43 W in BR and 285 ± 44 W in PLA. Peak and mean power during repeated sprinting were similar in BR and PLA. In contrast to observations in moderately trained subjects intake of BR juice had no effect on VO(2) kinetics and performance in elite cyclists.

The 10-20-30 training concept improves performance and health profile in moderately trained runners

The effect of an alteration from regular endurance to interval (10-20-30) training on the health profile, muscular adaptations, maximum oxygen uptake (V̇o2max), and performance of runners was examined. Eighteen moderately trained individuals (6 females and 12 males; V̇o2max: 52.2 ± 1.5 ml·kg−1·min−1) (means ± SE) were divided into a high-intensity training (10-20-30; 3 women and 7 men) and a control (CON; 3 women and 5 men) group. For a 7-wk intervention period the 10-20-30 replaced all training sessions with 10-20-30 training consisting of low-, moderate-, and high-speed running (<30%, <60%, and >90% of maximal intensity) for 30, 20, and 10 s, respectively, in three or four 5-min intervals interspersed by 2 min of recovery, reducing training volume by 54% (14.0 ± 0.9 vs. 30.4 ± 2.3 km/wk) while CON continued the normal training. After the intervention period V̇o2max in 10-20-30 was 4% higher, and performance in a 1,500-m and a 5-km run improved ( P < 0.05) by 21 and 48 s, respectively. In 10-20-30, systolic blood pressure was reduced ( P < 0.05) by 5 ± 2 mmHg, and total and low-density lipoprotein (LDL) cholesterol was lowered ( P < 0.05) by 0.5 ± 0.2 and 0.4 ± 0.1 mmol/l, respectively. No alterations were observed in CON. Muscle membrane proteins and enzyme activity did not change in either of the groups. The present study shows that interval training with short 10-s near-maximal bouts can improve performance and V̇o2max despite a ∼50% reduction in training volume. In addition, the 10-20-30 training regime lowers resting systolic blood pressure and blood cholesterol, suggesting a beneficial effect on the health profile of already trained individuals.

Pro- and anti-angiogenic factors in human skeletal muscle in response to acute exercise and training

This study examined the effect of acute exercise and 4 weeks of aerobic training on skeletal muscle gene and protein expression of pro- and anti-angiogenic factors in 14 young male subjects. Training consisted of 60 min of cycling (∼60% of ), 3 times/week. Biopsies were obtained from vastus lateralis muscle before and after training. Muscle interstitial fluid was collected during cycling at weeks 0 and 4. Training increased (P < 0.05) the capillary: fibre ratio and capillary density by 23% and 12%, respectively. The concentration of interstitial vascular endothelial growth factor (VEGF) in response to acute exercise increased similarly (>6-fold; P < 0.05) before and after training. Resting protein levels of soluble VEGF receptor-1 in interstitial fluid, and of VEGF, thrombospondin-1 (TSP-1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP1) in muscle were unaffected by training, whereas endothelial nitric oxide synthase protein levels in muscle increased by 50% (P < 0.05). Before and after training, acute exercise induced a similar increase (P < 0.05) in the mRNA level of angiopoietin 2, matrix metalloproteinase 9 and TSP-1. After training, TIMP1 mRNA content increased with exercise (P < 0.05). In conclusion, acute exercise induced a similar increase in the gene-expression of both pro- and anti-angiogenic factors in untrained and trained muscle. We propose that the increase in anti-angiogenic factors with exercise is important for modulation of angiogenesis. The lack of effect of training on basal muscle VEGF protein levels and VEGF secretion during exercise suggests that increased VEGF levels are not a prerequisite for exercise-induced capillary growth in healthy muscle.

Effect of whey protein- and carbohydrate-enriched diet on glycogen resynthesis during the first 48 h after a soccer game

The effect of a whey protein- and carbohydrate (CHO)-enriched diet on the rate of muscle glycogen resynthesis after a soccer match was examined. Sixteen elite soccer players were randomly assigned to a group ingesting a diet rich in carbohydrates and whey protein [CHO, protein, and fat content was 71, 21, and 8E%, respectively; high content of carbohydrates and whey protein (HCP), n = 9] or a group ingesting a normal diet (55, 18, and 26E%; control [CON], n = 7) during a 48-h recovery period after a soccer match. CON and three additional players carried out a 90- and 60-min simulated match without body contacts (SIM90 and SIM60). Muscle glycogen was lowered (P < 0.05) by 54, 48, 53, and 38% after the matches in CON, HCP, SIM90, and SIM60, respectively. Glycogen resynthesis during the first 48 h after the match was not different between CON and HCP, whereas glycogen resynthesis was slower (P < 0.05) during the first 24 h after SIM60 than SIM90 (2.88 ± 0.84 vs 4.32 ± 0.54 mmol/kg dw/h). In HCP, glycogen content in type II muscle fibers was still lowered 48 h after the match. In conclusion, glycogen resynthesis 48 h after a soccer match is not elevated by ingestion of a HCP diet. Furthermore, glycogen resynthesis does not appear to be impaired by body contacts during a match.

Speed endurance training is a powerful stimulus for physiological adaptations and performance improvements of athletes

The present article reviews the physiological and performance effects of speed endurance training consisting of exercise bouts at near maximal intensities in already trained subjects. Despite a reduction in training volume, speed endurance training of endurance-trained athletes can maintain the oxidative capacity and improve intense short-duration/repeated high-intensity exercise performance lasting 30 s to 4 min, as it occurs in a number of sports. When combined with a basic volume of training including some aerobic high-intensity sessions, speed endurance training is also useful in enhancing performance during longer events, e.g. 40 K cycling and 10 K running. Athletes in team sports involving intense exercise actions and endurance aspects can also benefit from performing speed endurance training. These improvements don't appear to depend on changes in maximum oxygen uptake (VO2max), muscle substrate levels, glycolytic and oxidative enzymes activity, and membrane transport proteins involved in pH regulation. Instead they appear to be related to a reduced energy expenditure during submaximal exercise and a higher expression of muscle Na(+) ,K(+) pump α-subunits, which via a higher Na(+) ,K(+) pump activity during exercise may delay fatigue development during intense exercise. In conclusion, athletes from disciplines involving periods of intense exercise can benefit from the inclusion of speed endurance sessions in their training programs.

The effect of passive movement training on angiogenic factors and capillary growth in human skeletal muscle

The effect of a period of passive movement training on angiogenic factors and capillarization in skeletal muscle was examined. Seven young males were subjected to passive training for 90 min, four times per week in a motor-driven knee extensor device that extended one knee passively at 80 cycles min₋₁. The other leg was used as control. Muscle biopsies were obtained from m. v. lateralis of both legs before as well as after 2 and 4 weeks of training. After the training period, passive movement and active exercise were performed with both legs, and muscle interstitial fluid was sampled from microdialysis probes in the thigh. After 2 weeks of training there was a 2-fold higher level of Ki-67 positive cells, co-localized with endothelial cells, in the passively trained leg which was paralleled by an increase in the number of capillaries around a fibre (P <0.05). Capillary density was higher than pre-training at 4 weeks of training (P <0.05). The training induced an increase in the mRNA level of endothelial nitric oxide synthase (eNOS), the angiopoietin receptor Tie-2 and matrix metalloproteinase (MMP)-9 in the passively trained leg and MMP-2 and tissue inhibitor of MMP (TIMP)-1 mRNA were elevated in both legs. Acute passive movement increased (P <0.05) muscle interstitial vascular endothelial growth factor (VEGF) levels 4- to 6-fold above rest and the proliferative effect, determined in vitro, of the muscle interstitial fluid ~16-fold compared to perfusate. The magnitude of increase was similar for active exercise. The results demonstrate that a period of passive movement promotes endothelial cell proliferation and angiogenic factors and initiates capillarization in skeletal muscle.

Sub-maximal and maximal Yo-Yo intermittent endurance test level 2: heart rate response, reproducibility and application to elite soccer

The aims of this study were to (1) determine the reproducibility of sub-maximal and maximal versions of the Yo-Yo intermittent endurance test level 2 (Yo-Yo IE2 test), (2) assess the relationship between the Yo-Yo IE2 test and match performance and (3) quantify the sensitivity of the Yo-Yo IE2 test to detect test-retest changes and discriminate between performance for different playing standards and positions in elite soccer. Elite (n = 148) and sub-elite male (n = 14) soccer players carried out the Yo-Yo IE2 test on several occasions over consecutive seasons. Test-retest coefficient of variation (CV) in Yo-Yo IE2 test performance and heart rate after 6 min were 3.9% (n = 37) and 1.4% (n = 32), respectively. Elite male senior and youth U19 players Yo-Yo IE2 performances were better (P < 0.01) than elite youth U16s and sub-elite players (2,603 ± 451 and 2,534 ± 549 vs. 1,855 ± 535 vs. 1,749 ± 382 m). The intra- and inter-season CV for Yo-Yo IE2 test performance were 4.2 and 5.6%, respectively. A correlation was observed (P < 0.05) between Yo-Yo IE2 test performance and the total (r = 0.74) and high-intensity (r = 0.58) running distance covered in a match. A correlation was also evident (P < 0.01) between Yo-Yo IE2 test heart rate after 6 min expressed in percentage of maximal heart rate and the peak values for high-intensity running performed by midfielders in 5-min (r = -0.71), 15-min (r = -0.75) and 45-min periods (r = -0.77). The present data demonstrate that the Yo-Yo IE2 test is reproducible and can be used to determine the capacity of elite soccer players to perform intense intermittent exercise. Furthermore, the Yo-Yo IE2 test was shown to be a sensitive tool that not only relates to match performance but can also differentiate between intermittent exercise performance of players in various standards, stages of the season and playing positions.

Long-term musculoskeletal and cardiac health effects of recreational football and running for premenopausal women

We examined long-term musculoskeletal and cardiac adaptations elicited by recreational football (FG, n=9) and running (RG, n=10) in untrained premenopausal women in comparison with a control group (CG, n=9). Training was performed for 16 months ( approximately 2 weekly 1-h sessions). For FG, right and left ventricular end-diastolic diameters were increased by 24% and 5% (P<0.05), respectively, after 16 months. Right ventricular systolic function measured by tricuspid annular plane systolic excursion (TAPSE) increased (P<0.05) in FG after 4 months and further (P<0.05) after 16 months (15% and 32%, respectively). In RG and CG, cardiac structure, E/A and TAPSE remained unchanged. For FG, whole-body bone mineral density (BMD) was 2.3% and 1.3% higher (P<0.05) after 16 months, than after 4 and 0 months, respectively, with no changes for RG and CG. FG demonstrated substantial improvements (P<0.05) in fast (27% and 16%) and slow (16% and 17%) eccentric muscle strength and rapid force capacity (Imp30ms: 66% and 65%) after 16 months compared with 4 and 0 months, with RG improving Imp30ms by 64% and 46%. In conclusion, long-term recreational football improved muscle function, postural balance and BMD in adult women with a potential favorable influence on the risk of falls and fractures. Moreover, football training induced consistent cardiac adaptations, which may have implications for long-term cardiovascular health.

Executive summary: the health and fitness benefits of regular participation in small-sided football games

The present special issue of Scandinavian Journal of Medicine & Science in Sports deals with health and fitness benefits of regular participation in small-sided football games. One review article and 13 original articles were the result of a 2-year multi-center study in Copenhagen and Zurich and include studies of different age groups analyzed from a physiological, medical, social and psychological perspective. The main groups investigated were middle-aged, former untrained, healthy men and women who were followed for up to 16 months. In addition, elderly, children and hypertensive patients were studied. A summary and interpretations of the main findings divided into an analysis of the physical demands during training of various groups and the effect of a period of training on performance, muscle adaptations and health profile follow. In addition, social and psychological effects on participation in recreational football are considered, the comparison of football training and endurance running is summarized and the effects of football practice on the elderly and children and youngsters are presented.

Beneficial effects of recreational football on the cardiovascular risk profile in untrained premenopausal women

The present study examined the cardiovascular health effects of 16 weeks of recreational football training in untrained premenopausal women in comparison with continuous running training. Fifty healthy women were matched and randomized to a football (FG, n=25) or a running (RG, n=25) group and compared with a control group with no physical training (CO, n=15). Training was performed for 1 h twice a week. After 16 weeks, systolic and diastolic blood pressure was reduced (P<0.05) in FG (7+/-2 and 4+/-1 mmHg) and systolic blood pressure was lowered (P<0.05) in RG (6+/-2 mmHg). After 16 weeks, resting heart rate was lowered (P<0.05) by 5+/-1 bpm both in FG and RG, and maximal oxygen uptake was elevated (P<0.05) by 15% in FG and by 10% in RG (5.0+/-0.7 and 3.6+/-0.6 mL/min/kg, respectively). Total fat mass decreased (P<0.05) by 1.4+/-0.3 kg in FG and by 1.1+/-0.3 kg in RG. After 16 weeks, pulse pressure wave augmentation index (-0.9+/-2.5 vs 4.2+/-2.4%), skeletal muscle capillarization (2.44+/-0.15 vs 2.07+/-0.05 cap/fib) and low-density lipoprotein/high-density lipoprotein cholesterol ratio were improved (P<0.05) in FG, but not altered in RG. No changes were observed in CO. In conclusion, regular recreational football training has significant favorable effects on the cardiovascular risk profile in untrained premenopausal women and is at the least as efficient as continuous running.

Effect of previous exhaustive exercise on metabolism and fatigue development during intense exercise in humans

The present study examined how metabolic response and work capacity are affected by previous exhaustive exercise. Seven subjects performed an exhaustive cycle exercise ( approximately 130%-max; EX2) after warm-up (CON) and 2 min after an exhaustive bout at a very high (VH; approximately 30 s), high (HI; approximately 3 min) or low (LO; approximately 2 h) intensity. Compared with CON, performance during EX2 was reduced (P<0.05) more in HI and LO than in VH (61+/-4% and 68+/-3% vs 35+/-4%). The muscle glycogen before EX2 was lower (P<0.05) in LO than in HI and VH, but the muscle glycogen utilization rates during EX2 were not different. Muscle glycogen concentration before EX2 was related (P<0.05) to the mean rate of muscle glycogen utilization during EX2 in HI and VH, and the mean rate of muscle lactate accumulation in LO. In HI, muscle pH before EX2 was lower (P<0.05) compared with VH and LO, but the same in HI and VH at the end of EX2. In HI, muscle pH before and after EX2 was inversely related (P<0.05) to the decrease in EX2 performance. Thus, muscle glycogen availability and low muscle pH do not per se control but appear to affect the rate of glycogenolysis/glycolysis and fatigue development during a repeated high-intensity exercise lasting 1/2-2 min.

Muscular and pulmonary O2 uptake kinetics during moderate- and high-intensity sub-maximal knee-extensor exercise in humans

The purpose of this investigation was to determine the contribution of muscle O(2) consumption (mVO2) to pulmonary O(2) uptake (pVO2) during both low-intensity (LI) and high-intensity (HI) knee-extension exercise, and during subsequent recovery, in humans. Seven healthy male subjects (age 20-25 years) completed a series of LI and HI square-wave exercise tests in which mVO2 (direct Fick technique) and pVO2 (indirect calorimetry) were measured simultaneously. The mean blood transit time from the muscle capillaries to the lung (MTTc-l) was also estimated (based on measured blood transit times from femoral artery to vein and vein to artery). The kinetics of mVO2 and pVO2 were modelled using non-linear regression. The time constant (tau) describing the phase II pVO2 kinetics following the onset of exercise was not significantly different from the mean response time (initial time delay + tau) for mVO2 kinetics for LI (30 +/- 3 vs 30 +/- 3 s) but was slightly higher (P < 0.05) for HI (32 +/- 3 vs 29 +/- 4 s); the responses were closely correlated (r = 0.95 and r = 0.95; P < 0.01) for both intensities. In recovery, agreement between the responses was more limited both for LI (36 +/- 4 vs 18 +/- 4 s, P < 0.05; r = -0.01) and HI (33 +/- 3 vs 27 +/- 3 s, P > 0.05; r = -0.40). MTTc-l was approximately 17 s just before exercise and decreased to 12 and 10 s after 5 s of exercise for LI and HI, respectively. These data indicate that the phase II pVO2 kinetics reflect mVO2 kinetics during exercise but not during recovery where caution in data interpretation is advised. Increased mVO2 probably makes a small contribution to during the first 15-20 s of exercise.

Recreational soccer is an effective health-promoting activity for untrained men

To examine the effects of regular participation in recreational soccer on health profile, 36 healthy untrained Danish men aged 20-43 years were randomised into a soccer group (SO; n = 13), a running group (RU; n = 12) and a control group (CO; n = 11). Training was performed for 1 h two or three times per week for 12 weeks; at an average heart rate of 82% (SEM 2%) and 82% (1%) of HR(max) for SO and RU, respectively. During the 12 week period, maximal oxygen uptake increased (p<0.05) by 13% (3%) and 8% (3%) in SO and RU, respectively. In SO, systolic and diastolic blood pressure were reduced (p<0.05) from 130 (2) to 122 (2) mm Hg and from 77 (2) to 72 (2) mm Hg, respectively, after 12 weeks, with similar decreases observed for RU. After the 12 weeks of training, fat mass was 3.0% (2.7 (0.6) kg) and 1.8% (1.8 (0.4) kg) lower (p<0.05) for SO and RU, respectively. Only SO had an increase in lean body mass (1.7 (0.4) kg, p<0.05), an increase in lower extremity bone mass (41 (8) g, p<0.05), a decrease in LDL-cholesterol (2.7 (0.2) to 2.3 (0.2) mmol/l; p<0.05) and an increase (p<0.05) in fat oxidation during running at 9.5 km/h. The number of capillaries per muscle fibre was 23% (4%) and 16% (7%) higher (p<0.05) in SO and RU, respectively, after 12 weeks. No changes in any of the measured variables were observed for CO. In conclusion, participation in regular recreational soccer training, organised as small-sided drills, has significant beneficial effects on health profile and physical capacity for untrained men, and in some aspects it is superior to frequent moderate-intensity running.