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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 responses in males and females?What is the main finding and its importance?Using resistance training methods that regulated the within‐set fatigue limit, males appeared to be more susceptible to fatigue than females before the training period. This between‐sex difference was diminished after training. The predominant mechanisms of fatigue from 20 and 40% velocity‐based resistance training appear to be within the musculature. Scientific examination of velocity‐based resistance training (VBRT) has increased recently, but how males and females respond to different VBRT protocols or how these acute responses are modified after a period of training is unknown. Habitually resistance‐trained males and females followed either a 20 or 40% velocity‐loss programme for 8 weeks. Acute squat loading tests (five sets, 70% one‐repetition maximum load, 3 min rest) were performed before and after the training period. Tests of maximum neuromuscular performance and blood sampling were conducted before, within 10 min of completion (POST) and 24 h after each acute loading test. Testing included countermovement jump, resting femoral nerve electrical stimulation and bilateral isometric leg press. Blood samples were analysed for whole‐blood lactate, serum testosterone, cortisol, growth hormone and creatine kinase concentrations. Countermovement jump height, maximum isometric bilateral leg‐press force and the force from a 10 Hz doublet decreased in all groups at POST after 20 and 40% velocity loss. Only males showed reduced force from the 100 Hz doublet and voluntary force over 100 ms at POST before training. The 40% velocity loss led to increased blood lactate and growth hormone responses before training in both males and females. After training, more systematic and equivalent responses in force over 100 ms, force from a 100 Hz doublet and blood lactate were observed regardless of sex/VBRT protocol. Overall, acute responses were greater from 40% VBRT, and males were more susceptible to acute loss in force production capacity before the training period. These VBRT protocol‐ and sex‐related differences were diminished after training. [ABSTRACT FROM AUTHOR]

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. A total of 23 biathletes fired 8 × 5 standing shots at rest (REST) and 2 × 5 shots during a race simulation (RACE). Shooting performance (hit point distance from the center of the target), aiming point trajectory and postural balance were measured from each shot. Shooting performance was similar both at REST (HOLD 33 ± 5 mm vs TIMING 38 ± 8 mm, P =.111) and in RACE (40 ± 11 mm vs 47 ± 12 mm, P =.194). Better shooting performance was related to smaller distance of the aiming point mean location (REST r = 0.93, P <.001, RACE r = 0.72, P =.018) and higher time spent within ⅔ of the distance of the hit area edge from the center 0.6‐0.0 seconds before triggering (REST r=−0.88, P =.001, RACE r=−0.73, P =.016) in HOLD, and to lower aiming point total velocity 0.6‐0.0 seconds before triggering (REST r = 0.77, P =.009, RACE r = 0.88, P =.001) and less aiming point movement 0.2‐0.0 seconds before triggering (REST r = 0.82, P =.003, RACE r = 0.72, P =.012) in TIMING. Postural balance was related to shooting performance at REST in both groups and in RACE in TIMING. Biathletes using the hold strategy should focus on stabilizing the aiming point before triggering and aiming at the center, whereas biathletes using the timing strategy benefit of decreasing the total velocity during the final approach as well as minimizing the aiming point movement right before triggering. [ABSTRACT FROM AUTHOR]

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 response to RT as reflected in metabolic health indicators and how age, sex, nutrition, and pre‐training phenotypes are associated with such variabilities. Methods: Previously collected data of men and women (39‐73 years, 135 trained, 73 non‐trained controls) were pooled for analysis. Measurements were taken twice before training to estimate individual day‐to‐day variations and measurement errors (n = 208). The individual responsiveness to the 21‐week RT in cardiometabolic health indicators (ie, systolic blood pressure, high‐density lipoprotein cholesterol (HDL‐C), cholesterol and triglycerides) was determined. Body composition was estimated by bioimpedance and dietary intake according to 4‐day food diaries. Results: Metabolic responses to RT seemed to be highly individual, and both beneficial and unfavorable changes were observed. Large inter‐individual variations in training response were not explained by a subject's age, sex, body composition, or nutritional status, with the exception of improvements in HDL‐C, which were associated with simultaneous decreases in body fat in older women. The incidence of metabolic syndrome diminished following RT. Conclusion: This study showed that RT could improve some specific metabolic health indicators beyond normal day‐to‐day variations, especially in blood lipid profile. Further studies are needed to elucidate genetic and other mechanisms underlining the heterogeneity of RT responses. This knowledge may be useful in providing individually tailored exercise prescriptions as part of personalized preventative health care. [ABSTRACT FROM AUTHOR]

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 power, and blood samples to determine serum hormone concentrations. The mean (±SD) age of subjects was 20 ± 1 years, height 180 ± 6 cm and body mass 72.4 ± 8.8 kg. The subjects were divided into three different training groups: soldier task‐specific training (TS), strength training (ST), and control (CON). Each group had a total of 18 training sessions during the 12‐week study. In the muscle strength tests, most improvements could be observed in the TS and ST groups, especially, during the first weeks of the training period. Maximal isometric leg extension force increased significantly by 7.9 ± 12.2% (p <.05) in the TS and 7.1 ± 12.6% (p <.05) in the ST groups between the PRE and MID, as well as between the PRE and POST measurements by 8.1 ± 12.4% (p <.05) in TS and 12.3 ± 15.3% (p <.01) in ST. Serum TES concentration increased significantly in TS between the PRE and MID (16.8 ± 33.9%) and PRE and POST (11.2 ± 16.7%) measurements. Serum COR concentrations decreased in TS between the MID and POST (−7.8 ± 10.9%) and PRE and POST (−11.0 ± 14.3%) measurements. Although the differences observed were rather minor in magnitude, training in the TS and ST groups led to greater improvements in muscle strength and power performance compared to the training in the CON group. The development of strength and/or power of the lower and upper body was greater in the TS and ST groups, which is crucial for warfighter's performance. Therefore, it is important to have a structured resistance‐training program during military training to optimize the strength, power, and military‐specific performance. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study?Although acute responses of the principal gonadosteroid and corticosteroid hormones to resistance exercise are well documented, there is no information regarding how the key lower‐concentration intermediary hormones respond and potentially influence these hormonal pathways.What is the main finding and its importance?This study provides evidence for cascading conversions of some gonadosteroids, and the data suggest that the testosterone concentration increases independently of these hormones. These findings challenge future studies to determine the exact physiological roles of the lower‐concentration gonadosteroids and corticosteroids during and immediately after resistance exercise. Resistance training is a potent stimulus for muscle growth, and steroid hormones are known to play a role in this adaptation. However, very little is known about the acute exercise‐induced gonadosteroid and corticosteroid hormone responses, including those of key lower‐concentration intermediate hormones. The present study determined the acute responses of these steroid hormone families using quantitative ultra‐high performance liquid chromatography tandem mass spectrometry after resistance exercise in strength‐trained men. Venous and fingertip blood samples were obtained pre‐, mid‐, 5 min post‐ and 15 min post‐resistance exercise, both before and after 10 weeks of supervised resistance training. The experimental resistance exercise sessions consisted of three sets of 10 repetitions of bilateral leg‐press exercise and three sets of 10 repetitions of unilateral knee‐extension exercise, with 2 and 1 min recovery between sets, respectively. Statistically significant (P < 0.05) increases in the concentration of hormones in the gonadosteroid [including dehydroepiandrosterone (DHEA), androstenedione, testosterone and estrone] and the corticosteroid (including cortisol, corticosterone and cortisone) families were demonstrated after both experimental resistance exercise sessions, irrespective of training status. Correlation analyses revealed relationships between the following hormones: (i) DHEA and androstenedione; (ii) DHEA and cortisol; (iii) androstenedione and estrone; and (iv) 11‐deoxycortisol and cortisol. Testosterone appears to increase acutely and independently of other intermediary hormones after resistance exercise. In conclusion, lower‐concentration intermediary gonadosteroids (e.g. estrone) and corticosteroids (e.g. corticosterone) respond robustly to resistance exercise in strength‐trained men, although it seems that testosterone concentrations are regulated by factors other than the availability of precursor hormones and changes in plasma volume. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor-I (IGF-I) and its splice variants Insulin-like growth factor-I isoform Ea (IGF-IEa) and mechano growth factor (MGF) may play an important role in muscular adaptations to resistance training (RT) that may be modulated by ageing. It has been suggested that IGF-I induces cellular responses via AKT8 virus oncogene cellular homolog (Akt) and Extracellular signal-regulated kinase (Erk) signalling pathways. Therefore, resistance exercise-induced changes in skeletal muscle IGF-IEa and MGF messenger ribonucleic acid (mRNA), and MGF, Erk1/2, Akt and p70S6K protein expression were investigated before and after 21 weeks of RT in younger (YM, 20–34 yrs.,n = 7) and older men (OM, 51–71 yrs.,n = 10). Experimental resistance exercises (RE) of 5 × 10 repetition maximum leg presses were performed pre- and post-RT. Muscle biopsies were obtained before and 48 h after REs, to study the late response to muscle loading. The muscle proteins or mRNAs of interest were not systematically influenced by the REs or RT, except for MGF mRNA expression which was increased (p < .01) following RE before RT in OM. No differences were observed between YM and OM in any variables. This study demonstrated that basal levels or RE-induced responses in skeletal muscle MGF, Erk1/2, Akt and p70S6K protein levels or IGF-IEa and MGF mRNA expression did not differ between YM and OM, nor change systematically due to RT. Thus, ageing appears not to effect expression of the present signalling molecules involved in skeletal muscle hypertrophy. [ABSTRACT FROM PUBLISHER]

The present study was designed to analyse and compare the kinetics and kinematics associated with three different starting strategies during classic cross-country ski racing. Inside a ski tunnel, 12 elite male skiers performed three sets of three 38 m starts. Each set included one start using: double poling only (DP), diagonal stride only (DIA) and freely chosen (FREE) (i.e. where subjects used the strategy or combination of strategies they felt was fastest) in random order. The first 18 m was performed on a series of force plates that measured horizontal and vertical forces followed by 20 m of a standard snow track. Additionally, cycle characteristics and joint angles were measured. DIA and FREE were faster over 38 m than DP (P < .01). Net horizontal impulse (taking into account both positive and negative impulses) 5–10 m after the start was lower during DP than during DIA and FREE (bothP < .05). All subjects skied faster when using only DIA for the entire 38 m. Furthermore, the sum duration and frequency of propulsive contacts over the first 18 m was less in DP than DIA and FREE (P < .01). In conclusion, differences between the starting strategies examined was especially pronounced during the initial cycles. Transition from DIA to DP during the start also slowed the skiers, but optimal timing for such a transition was not elucidated. [ABSTRACT FROM PUBLISHER]

The primary aim of the present study was to investigate the acute gene expression responses of PGC-1 isoforms and PGC-1α target genes related to mitochondrial biogenesis ( cytochrome C), angiogenesis ( VEGF-A), and muscle hypertrophy (myostatin), after a resistance or endurance exercise bout. In addition, the study aimed to elucidate whether the expression changes of studied transcripts were linked to phosphorylation of AMPK and MAPK p38. Nineteen physically active men were divided into resistance exercise ( RE, n = 11) and endurance exercise ( EE, n = 8) groups. RE group performed leg press exercise (10 × 10 RM, 50 min) and EE walked on a treadmill (~80% HRmax, 50 min). Muscle biopsies were obtained from the vastus lateralis muscle before, 30 min, and 180 min after exercise. EE and RE significantly increased the gene expression of alternative promoter originated PGC-1α exon 1b- and 1bxs'-derived isoforms, whereas the proximal promoter originated exon 1a-derived transcripts were less inducible and were upregulated only after EE. Truncated PGC-1α transcripts were upregulated both after EE and RE. Neither RE nor EE affected the expression of PGC-1β. EE upregulated the expression of cytochrome C and VEGF-A, whereas RE upregulated VEGF-A and downregulated myostatin. Both EE and RE increased the levels of p- AMPK and p- MAPK p38, but these changes were not linked to the gene expression responses of PGC-1 isoforms. The present study comprehensively assayed PGC-1 transcripts in human skeletal muscle and showed exercise mode-specific responses thus improving the understanding of early signaling events in exercise-induced muscle adaptations. [ABSTRACT FROM AUTHOR]

Key points Contradictory findings have been reported concerning the function of irisin and its precursor gene, skeletal muscle FNDC5, in energy homeostasis and metabolic health, and the associated regulatory role of exercise and PGC-1α., We analysed the effects of different short- and long-term exercise regimens on muscle FNDC5 and PGC-1α, and serum irisin, and studied the associations of irisin and FNDC5 with health parameters., FNDC5 and serum irisin did not change after acute aerobic, long-term endurance training or endurance training combined with resistance exercise (RE) training, or associate with metabolic disturbances. A single RE bout increased FNDC5 mRNA in young, but not older men (27 vs. 62 years). Changes in PGC-1α or serum irisin were not consistently accompanied by changes in FNDC5., Our data suggest that the effects of exercise on FNDC5 and irisin are not consistent, and that their role in health is questionable. Moreover, the regulatory mechanisms should be studied further., Abstract Recently, contradictory findings have been reported concerning the function of irisin and its precursor gene, skeletal muscle FNDC5, in energy homeostasis, and the associated regulatory role of exercise and PGC-1α. We therefore evaluated whether muscle FNDC5 mRNA and serum irisin are exercise responsive and whether PGC-1α expression is associated with FNDC5 expression. The male subjects in the study performed single exercises: (1) 1 h low-intensity aerobic exercise (AE) (middle-aged, n= 17), (2) a heavy-intensity resistance exercise (RE) bout (young n= 10, older n= 11) (27 vs. 62 years), (3) long-term 21 weeks endurance exercise (EE) training alone (twice a week, middle-aged, n= 9), or (4) combined EE and RE training (both twice a week, middle-aged, n= 9). Skeletal muscle mRNA expression was analysed by quantitative PCR and serum irisin by ELISA. No significant changes were observed in skeletal muscle PGC-1α, FNDC5 and serum irisin after AE, EE training or combined EE + RE training. However, a single RE bout increased PGC-1α by 4-fold in young and by 2-fold in older men, while FNDC5 mRNA only increased in young men post-RE, by 1.4-fold. Changes in PGC-1α or serum irisin were not consistently accompanied by changes in FNDC5. In conclusion, for the most part, neither longer-term nor single exercise markedly increases skeletal muscle FNDC5 expression or serum irisin. Therefore their changes in response to exercise are probably random and not consistent excluding the confirmation of any definitive link between exercise and FNDC5 expression and irisin release in humans. Moreover, irisin and FNDC5 were not associated with glucose tolerance and being overweight, or with metabolic disturbances, respectively. Finally, factor(s) other than PGC-1α and transcription may regulate FNDC5 expression. [ABSTRACT FROM AUTHOR]

The autonomic nervous system and circulating hormones control a stress reaction through a complex interaction. We tested the hypothesis that changes in cardiac vagal regulation may be positively associated with the serum testosterone-to-cortisol ratio during the first week of military service in 24 conscripts aged 19.0±0.3 years. Cardiac autonomic function was assessed by measuring high-frequency (HF: 0.15-0.4 Hz) and low-frequency (LF: 0.04-0.15 Hz) power spectral indices of R-R intervals during supine rest and during a controlled standing condition (5 min for both) from the second to the seventh mornings at the beginning of military service. Blood samples were collected to analyse the basal serum testosterone-to-cortisol ratio on the seventh morning. Changes in heart rate and high-frequency power measured in the standing condition were positively correlated with the serum testosterone-to-cortisol ratio at day 7 (r= - 0.42 and r=0.45, respectively; P<0.05 for both). However, changes in low-frequency power and LF/HF ratio did not correlate with testosterone or cortisol concentration. The present results suggest a relationship between changes in cardiac vagal regulation during a long-term mentally stressful condition and the serum testosterone-to-cortisol ratio. This association was more marked during the controlled standing condition. [ABSTRACT FROM AUTHOR]

Aim : To compare the neuromuscular function and balance of blind prepuberty- and puberty-aged boys to those with normal sight. Methods : Thirty-three prepubertal (aged 9–13 y) and pubertal (aged 15–18 y) blind and sighted boys were tested for muscle mass thickness, electromyography and maximal isometric strength, dynamic explosive actions, and balance. Results : There was no difference in the muscle mass thickness, maximal strength or vertical jump between the blind and sighted boys. However, fitness-ball throwing and five-jump distances were significantly shorter in both blind groups compared to the sighted groups. One-leg stance of the prepuberty-aged sighted boys was 109 (67) s and in blind boys 32 (12) s, and in the puberty-aged boys 120 (57) s and 31 (8) s, respectively. When vision was blocked in the sighted boys, differences between the blind and sighted boys disappeared. Conclusion : The results showed comparable performance between prepubertal and pubertal blind and sighted boys in the static physical fitness tests. However, balance and performance in dynamic multi-joint tests did not improve similarly in the blind groups compared to sighted groups, indicating that maturation, learning and experience by themselves cannot compensate for the loss of sight. [ABSTRACT FROM AUTHOR]

Objective: To examine heavy-resistance exercise-induced acute neuromuscular fatigue, blood lactate concentration, and muscle pain in elderly women with fibromyalgia (FM) and in healthy controls before and after a period of strength training., Methods: Thirteen elderly women with FM (mean+/-SD age 60+/-2 years) and 10 healthy women (mean+/-SD age 64+/-3 years) performed a heavy-resistance fatiguing protocol (5 sets of leg presses with 10 repetitions maximum) before and after a 21-week strength training period. Maximal isometric force and electromyography (EMG) activity of leg extensors and blood lactate concentration were measured during the loading. Pain was assessed by visual analog scale., Results: The strength training led to large increases in maximal force and EMG activity of the muscles and contributed to the improvement in loading performance (average load/set) at week 21. The fatiguing loading sessions typically applied in strength training before and after the experimental period caused remarkable and comparable acute decreases in maximal force and increases in blood lactate concentration in both groups. Acute exercise-induced muscle pain increased similarly in both groups, and the pain level in women with FM was lowered after the 21-week training period., Conclusion: The increased strength in women with FM improved high-load performance and also seemed to attenuate perceived pain. Acute exercise-induced neuromuscular changes and the time course of muscle pain in women with FM were comparable with findings in healthy controls, which suggests a typical fatiguing process and a similar trainability of the muscles in elderly women with FM.